Table of Contents
The
Skeletal System
Bone
Ligaments
Cartilage
Bone Repair
Skeleton
Axial Skeleton
Skull
Vertebral Column
The Ribs and
Sternum
Appendicular Skeleton
Pectoral Girdle
Pelvic Girdle
Joints
The Muscular System
Skeletal Muscle
Individual Muscle Cells
Cardiac and Smooth Muscle
Elements
of Functions of Blood
Plasma
Red Blood Cells
Oxygen Carrying Capacity
White Blood Cells
Platelets
Hemostasis
Blood Types
A, B, AB, or O
RH Factor
Blood Typing
Cardiovascular
System
Blood Vessels
Arteries
Capillaries
Veins
The Heart
Pulmonary Circuit
Systemic Circuit
The
Immune System
Pathogens
Transmission of Pathogens
Biology in the News
Lymphatic System
Lymph Nodes
The Spleen
Thymus Gland
Tonsils
First Line of Defense Against
Pathogens
The Second Line of Defense
White Blood Cells
Inflammation
Natural Killer Cells
Complement System
Interferon
Fever
The Third Line of Defense
Antigens
Lymphocytes
Immune Memory
Medical Assistance in Fighting
Pathogens
Immunizations
Inappropriate Immune System Activity
Allergies
Autoimmune Disorders
The
Respiratory System
Respiration
Upper Respiratory System
Lower Respiratory Tract
Breathing Process
Gas Exchange
The Nervous System Regulates Breathing
Respiratory Disorders
Disorders that Impede
Respiratory Function
Respiratory Disorders from
Microorganisms
Lung Cancer
Pneumothorax and Atalectasis
Congestive Heart Failure
If the
kidneys thing there is not enough oxygen available, it produces a hormone
called erythropoietin. Erythropoietin causes stem cells to make more red blood
cells. When the kidneys register there is enough oxygen available, it cuts back
on erythropoietin to slow down the production of red blood cells.
The Skeletal System
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| (Learning) |
The skeletal
system is made from bones, ligaments and cartilage, which are types of
connective tissues.
Bone
Bone is
mostly made of nonliving extracellular crystals of calcium minerals. But it
also is made from a living tissue that is made from more than one type of cell,
nerves and blood vessels. Bones have five jobs. The first job is to provide
support. Without support we wouldn’t be able to sit or stand. The second job is
to provide protection. Bones protect many internal organs like the lungs, liver
and spleen by surrounding them. The third is movement. Bones are attached to
muscle and that is what makes our bodies able to move. The fourth job is blood
cell formation. Cells in some bones are the only source of new red and white
blood cells and platelets. Without these cells you would die. The last job is
mineral storage. Calcium and phosphate are two minerals which are stored in
bone until they are needed.
The long part
of the bone is called the diaphysis. At the ends of the diaphysis is the
epiphysis which looks like a knob. The diaphysis is made of compact bone. The
center of the bone contains yellow bone marrow which is mostly fat. The bone is
surrounded by connective tissue called periosteum that holds bone forming
cells. If the epiphysis connects to another bone, there will be a moveable
joint. That joint will be covered with cartilage to prevent rubbing. The
epiphysis is made out of spongy bone. The spaces between the bone contain red
bone marrow and the stem cells in them are responsible for making red and white
blood cells and platelets.
Ligaments
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| (About.comOrthopedics) |
Ligaments are
a fibrous connective tissue that gives strength to some joints. They attach
bone to bone. They are made from collagen fibers that are placed close
together. They are all in the same direction and have fibroblasts between them.
Cartilage
Cartilage is
made from fibers of collagen or elastin and other things. It is smooth and
flexible and is found places that need support when they are under pressure.
There are three kinds of cartilage. Fibrocartilage is made mostly of collagen
fibers that are in thick bundles and can handle pressure and tension. It is
found in the vertebrae and knee. Hyaline cartilage is smooth and glassy and
made from thin collagen fibers. It forms in the embryo and later becomes the
bone. It also covers the ends of bones that are in joints. Elastic cartilage is
made from elastin fibers and is extremely flexible. If is found in the outer
ear and the epiglottis.
Bone
Repair
Bone is
always being replaced, repaired and remodeled. This is done by the bone cell
osteoclast. When a bone has been remodeled, it can change the bones shape.
Jogging and weight lifting and other weight bearing exercises will increase the
bone mass in your body and the strength of the bone. When you break a bone a
hematoma is formed in the broken area. Fibroblasts then travel to where the
break is to begin repair. They turn into chondroblasts and make a bond called
callus between the ends of the break. Then osteoclasts cone and take away the
fragments and the hematoma then osteoblasts bring osteoid matrix and make the
calcium phosphate minerals crystallize which turn the callus into bone. The
repaired part is thicker than the original bone.
Skeleton
The skeleton
is all of the bones of the body and the connective tissues that hold them
together. The skeleton has three jobs. The first job is providing support to
soft organs. The second job is to protect organs from injury. The third is to
allow movement. The skeleton is divided into the parts, the axial skeleton and
appendicular skeleton.
Axial Skeleton
The axial
skeleton is made up of the skull, sternum, ribs and vertebral column.
Skull
The skull is
made of over two dozen bones and its job is to protect the brain and make up
the face structure. It consists of cranial bones that are flat and they protect
the brain. The frontal bone begins at the front of the skull and makes up the
forehead and eye sockets. The left and right sides of the skull have parietal
bones and at the lower left and right sides are the temporal bones. The
sphenoid bone makes up the back of the eye sockets. The ethmoid bone is also
part of the eye sock and supports the nose. There are two nasal bones under the
upper part of the nose; the rest of the nose is cartilage and connective
tissue. There are small bones at the inner eye socket called lacrimal bones and
have a tiny opening that tears drain from the tear ducts in the eye socket to
the nasal cavity. The mandible bone is the lower jaw. The back of the skull is
where the occipital bone is found. Facial bones are found at the front of the
skull. Maxilla bones are on each side of the nose. The palate is made of
maxilla bones and palatine bones. The vomer bone is behind the palatine bone
and is part of the nasal septum. Zygomatic bones are the cheekbones and the
outer eye socket. There are air spaces in some of these bones and they are
called sinuses. The sinus is next to tissue that makes mucus. Sinuses are
connected to the nasal cavity which is where mucus drains.
Vertebral Column
The vertebral
column provides support to the head, protects the spinal cord, all four limbs
are attached to it, and some muscles. It is made of 33 bones called vertebrae.
There are 7 vertebrae in the neck called cervical vertebrae, 12 in the chest
called thoracic vertebrae, 5 in the lower back called lumbar vertebrae, 5 in
the pelvis called sacral and the 4 coccygeal vertebrae in the tailbone.
The Ribs and
Sternum
The ribs and
sternum have the job of protecting the chest cavity. There are 12 pairs of ribs
in humans. One end of the rib comes from the thoracic part of the vertebral
column. The other part is connected to cartilage which is connected to the
sternum. The sternum is sometimes called the breastbone. It is a flat bone that
is shaped like a blade and is actually made up of 3 bones that fuse together.
The bottom two pairs of ribs are not connected to the sternum and are called
floating ribs. The ribs, sternum and vertebral column make up the rib cage. The
rib cage protects the heart, lungs and any other organs found in the chest
cavity.
Appendicular Skeleton
The
appendicular skeleton is made up of the arms, legs, pectoral girdle and pelvic
girdle.
Pectoral Girdle
The pectoral
girdle includes the clavicles, which are collarbones and the scapula which are the
shoulder blades. These provide support to the upper limbs. The arm and hand are
made up of 30 kinds of bones.
Pelvic Girdle
The pelvic
girdle includes the coxal bones, the sacrum and coccyx. The pelvic girdle
supports the weight of the upper body, protects organs that are in the pelvic
cavity and is where the legs are attached.
Joints
There are
three kinds of joints. The first kind is fibrous joint and they cannot move. The
cartilaginous joint is another kind. In this joint, hyaline cartilage connects
bones and there is some flexibility. Synovial joints are the third type of
joint. This joint keeps bones apart by a cavity that is filled with a thin
layer of fluid. The bones are connected by ligaments.
Ligaments,
tendons and muscle provide strength to joints and help to keep joints stable.
The Muscular System
The muscular
system is made up of three types of muscle. They are skeletal muscle, cardiac
muscle and smooth muscle. Muscle is what makes us move or resist moving and
make hear. Muscle cells contract when a chemical or electrical signal is given
from other organs. Muscles shorten and then go back to their original length.
Skeletal Muscle
Skeletal muscle
is what makes bones move or stops them from moving. There are more than 600
skeletal muscles. Synergistic muscles work together and antagonistic muscles
against each other. Single muscle is made of muscle cells that all have the
same origin, insertion and function. Cross section muscle is a bundle of
fascicles that are surrounded by fibrous connective tissue called fascia. Each
muscle cell has more than one nucleus. The inside of the muscle cell is filled
with long cylinders that are called myofibrils. A myofibril has a banded
appearance that is repeated. There is a Z-line located in the myofibril. A
piece of myofibril going from on Z-line to the next is called the sarcomere.
The sarcomeres all shortening at the same time is what causes muscle to
contract. A sarcomere has 2 kinds of protein filaments, myosin and actin. Actin
filaments are connected to the Z-line and myosin filament is found in the
sarcomere.
Individual Muscle Cells
When muscles
contract, every sarcomere becomes just a little shorter. For muscles to contract,
four things must happen. First, the muscle cell needs to be turned on by a
nerve. These nerves are motor neurons that release a chemical called
acetylcholine. Next, the muscle cell sends out an electrical impulse that goes
to the sarcoplasmic reticulum. This releases calcium ions and the calcium
spreads out into the cell cytoplasm where it reaches the myofibrils. Calcium
causes the sliding filament mechanism to begin. This causes the myosin to
connect with the thin filaments and makes a cross bridge. Contractions only
happen when there is calcium present. When the nerve activity ends, muscle
relaxation begins.
Cardiac and Smooth Muscle
Cardiac and
smooth muscle are involuntary muscle because we don’t have any control over
them. They contract without any nerve activating them. Cardiac muscle contains
pacemaker cells that stimulate each other and set the pace of contraction of
the heart. Smooth muscle cells also activate each other. They also respond to
nerve activity, such as the heart rate going up during exercise. The cardiac
muscle has a slower rate of speed and sustainability of contractions than
skeletal muscle and smooth muscle is even slower. Cardiac muscle goes through
periods of contraction and relaxation so the muscle doesn’t become tired.
Smooth muscle is partly contracted almost always. It contracts so slowly that
it doesn’t become tired. Cardiac muscle is made of filaments that are in
sarcomeres like skeletal muscle is. Smooth muscle is made of thick and thin
filaments that are in bundles at different angles to the cell membrane.
Elements
of Functions of Blood
Blood is a
type of connective tissue. It has three important jobs that it performs. The
first is blood transports substances to any part of the body. These substances
include oxygen, nutrients and hormones. It transports waste products so that
they can be eliminated from the body. The second important job is blood
regulates the body temperature, the amount of water in the body and the pH of
body fluids. The third important job is blood has defense cells that help fight
off disease. Blood has the ability to clot so that there is not an excess of
blood lost. These jobs are essential so that there is stability.
Blood is
composed of liquid components called plasma and elements, which are the red
cells, white cells and the platelets. If blood is collected in a tube then spun
around in a special rotation device, the elements will fall to the bottom of
the tube and the plasma will go to the top. This happens because elements are
denser than the plasma. Red blood cells are at the bottom and are red in color.
About 44% of the sample is red blood cells. White blood cells and platelets are
next and are a grayish color and are about 1% of the sample. The other 55% is
plasma and is located at the top of the sample. Plasma is a pale yellow color.
Plasma
Plasma is
made mostly of water, about 90%. The other 10% is made up of proteins,
hormones, amino acids, fats, small carbohydrate, vitamins, waste product and
other small molecules and ions. Plasmas
function is to transport blood cells and platelets.
After water,
plasma is mostly made of plasma proteins and these proteins perform many
different jobs. Three of the proteins are albumins, globulins and clotting
proteins. Most of the proteins are albumins, around 2/3. The jobs of albumins
are to keep the right balance of water between blood and interstitial fluid and
to bind to some molecules and drugs and help them be transported through the
blood. Globulins are proteins that bind to lipid molecules and help move them
through the blood. When proteins bind to lipids it is called lipoprotein. Many
people are familiar with the terms LDL and HDL which refer to cholesterol
levels in the blood. High levels of LDL indicate a person is at a high risk of
cardiovascular problems and high levels of HDL levels indicate a lower risk of
cardiovascular health issues. The third protein is clotting proteins which help
the blood to clot so a person does not lose too much blood. Plasma also moves
many molecules through the blood.
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| (The Franklin Instute) |
Red
Blood Cells
After plasma
the next component of blood is red blood cells or erythrocytes. The main job is
to carry oxygen and carbon dioxide. They give blood its color and its
stickiness. They are small, circular and donut shaped with the middle thinner
than the outside edges. They are able to bend so they can fit through even the
tiniest blood vessel. Mature red blood cells do not have a nucleus or organelle
so they do not reproduce. Blood cells are made from stem cells which are found
in some bone marrow. Stem cells divide and are made into platelets, red and
white blood cells. It takes about a week for red blood cells to mature. Red
blood cells are filled with almost 300 million molecules of hemoglobin, which
is an oxygen binding protein. Hemoglobin is made up of four polypeptide chains
and each chain has a heme with an iron atom in the middle of it. A red blood
cell can hold 1.2 billion molecules of oxygen. They do not use any of the
oxygen they hold, they just carry it. Hemoglobin attaches best to oxygen when
there is a high amount of oxygen and a neutral Ph, which is the condition found
in the lungs. Oxygen first enters the plasma then goes into the red blood
cells. Once it enters the red blood cells it binds to the iron in the
hemoglobin. This removes some of the oxygen from the plasma which makes room
for more oxygen to enter the plasma. Once the hemoglobin has four oxygen
molecules attached, it is call oxyhemoglobin and is a bright red color. When
the hemoglobin reaches the tissue that needs the oxygen, it releases it. When
hemoglobin releases its oxygen it is called deoxyhemoglobin and is now a dark
purple color. When the hemoglobin is at a tissue that has a high level of
carbon dioxide, the carbon dioxide attaches to it and it is carried back to the
lungs where it is released and then expressed by breathing out. Red blood cells
have a life span of around 120 days. They are very busy during their short life
and make around 3000 round trips a day carrying oxygen from the lungs to tissue
and then carrying carbon dioxide back to the lungs. There are around 2 million
blood cells made a second. This high amount is needed to keep the hematocrit at
an even level. Once a cell is no longer able to do its job, it is destroyed in
the liver and spleen by a macrophage which is made from white blood cells. The
process is referred to as phagocytosis. The amino acids are recycled and the
iron atoms go back to the bone morrow. The liver turns this into bilirubin
which passes through the intestines. If the liver does not do this properly,
jaundice may occur. The skin and eyes turn yellow when jaundice is present.
Oxygen
Carrying Capacity
Hematocrit is
the percentage of blood that is made up of red blood cells. This is a way that
the oxygen carrying capacity of the blood can be measured. A low hematocrit may
indicate the patient has anemia or a disorder that results in the level of red
blood cell being made too low. A high hematocrit may indicate polycythemia
which is a disease of the bone marrow made by there being too many red blood cells.
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| (High White Blood Cell Count) |
White
Blood Cells
White blood
cells are bigger than red blood cells. White blood cells are also made from
stem cells. There are a much smaller number of these than of red blood cells
and they are translucent. They help to protect against diseases and injuries.
There are two types of white blood cells, granular leukocytes and agranular
leukocytes. They both have granules that contain proteins and enzymes but
agranular leukocyte granules cannot be seen unless some sort of stain is added.
The life span of a leukocyte is anywhere from a couple of hours to nine days.
Monocytes are another type of white blood cell and their life span can be a
couple of months. Lymphocytes survive for a couple of days to years. The number
of white blood cells becomes higher when the body is fighting sickness. When
more white blood cells are needed, they give off a chemical that causes the
bone marrow to make more. It also causes the spleen to let out stored white
blood cells. White blood cells can change shape so they are able to travel
through the body without any issues.
Types of
granular leukocytes are neutrophils, eosinophils and basophils. Neutrophils are
the most common type. They mostly fight off bacteria by surrounding and
absorbing the unknown cell. The next most common type is eosinophils.
Eosinophils main function is to protect against parasites. They band together
and attack the parasite with digestive enzymes. Their other job has to do with
putting out chemicals so allergic reactions are not as severe. Basophils are
the least common. Their function is to carry histamine which helps injured
tissues heal.
The two types
of agranular leukocytes are monocytes and lymphocytes. Monocytes can leave the
bloodstream and go into tissue where they change so that they can absorb foreign
cells. They also cause lymphocytes is be made when needed. There are two types
of lymphocytes, B lymphocytes and T lymphocytes. B lymphocytes cause plasma
that makes antibodies to be made. T lymphocytes nullify bacteria, viruses and
cancer.
Platelets
Platelets are
necessary for blood to be able to clot. Platelets are parts of megakaryocyte
cytoplasm and cell membrane. They are not living and have a short life span, 5
to 9 days. They help bleeding to stop and then when it has stopped they help
repair the injury by letting out proteins.
Hemostasis
Hemostasis is
the procedure the circulatory system follows to stop blood loss and is one of
the most important functions it has. There are three stages this process
follows. The first is vascular spasm. During this process the muscle in the
blood vessel goes through spasms lasting around half an hour. If the injury is
small the spasms may cause the walls to come together and the bleeding may
stop. The second stage is a platelet plug is formed. The platelets form
together and become sticky. They stick to the walls and each other. They will
eventually form a plug that will close the injury. If the injury is small this
can happen in seconds. In larger injuries, the third stage, blood clotting
occurs. When blood clots it changes into a gel substance. There are many
substances, at least 12, called clotting factors that make this happen. One of
them is called prothrombin activator. When then platelets get prothrombin
activator out it causes prothrombin, which is a protein to change into an
enzyme that is called thrombin. Calcium ions are needed for this to happen.
Thrombin then changed the plasma protein fibrinogen, a soluble plasma protein,
into an insoluble protein, fibrin. Fibrin is long strands that go around the
platelet plug and keeps the platelets and blood cells pressed against the
injury. This can form a blood clot in less than a minute. After this happens,
the platelets begin to draw in and tighten. If any of this does not happen, a
cut or bruise could cause death. Hemophilia is a disease that is caused by damaged
clotting factors. People used to die from hemophilia but today is can usually
be treated by giving the patient clotting factor VIII. Some medications can
also affect the hemostasis process.
Blood
Types
A,
B, AB, or O
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| (Biology Corner) |
Blood type is
determined by the type of antigen a red blood cell has. Antigens cause the
immune system to make antibodies. There are for types of blood. Type A has the
antigen A and the plasma antibody B, type B blood has the antigen B in the red
blood cells and the plasma has antibody A, blood type AB has both the antigen A
and B and does not have either A or B antibodies and Type O blood, which does
not contain A or B antigens but has both A and B antibodies. It is important to
know what type of blood you have if you may have to receive a blood
transfusion. If you receive a type of blood that has the antigen that your
blood does not have, agglutination may occur. This is when the antibodies
attack the unknown antigens. This causes them to clump together and the clumps
can block blood vessels. This may lead to organs being damaged or in extreme
cases, death.
Rh Factor
There is also
an antigen called the Rh factor. You may be either Rh positive or Rh negative.
If you are Rh positive you have the Rh antigen in your red blood cells and if
you are Rh negative you do not have the Rh antigen. If you are Rh negative and
are exposed to Rh antigen your body will make antibodies against it. This is
most concerning for women who are Rh negative and are pregnant. At birth, the
mother is generally exposed to her baby’s blood. If the baby if Rh positive,
the mother will begin to make antibodies. In her future pregnancies, the
antibodies may enter the placenta and attack the baby’s red blood cells. This
can cause hemolytic disease of the newborn and can result in mental retardation
or in extreme cases death. To prevent this, an Rh negative mother is given a
shot of anti Rh antibodies at 28 weeks of pregnancy and soon after birth.
Blood Typing
To determine
what type of blood a person has a sample of blood is drawn and then plasma with
anti-A and anti-B antibodies is added. If the blood agglutinates then it is
know that the blood contains the same antigens as the antibodies that were
added.
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| (Innerbody) |
Cardiovascular System
Blood
Vessels
Blood is
moved through the body by blood vessels. There are three types of blood
vessels.
Arteries
The first
type is arteries. Arteries have thick walls and their job is to deliver blood
to body tissue. Blood is transferred from the heart into the arteries and they
move the blood away from the heart. They have thick walls and muscle so they
can handle the pressure near the heart. Arteries branch off and become smaller
the further they are from the heart. They are stiff but do stretch when
necessary. The walls have three layers to them. The first or inner layer is
called the endothelium and keeps the flow of blood functioning smoothly. The
next layer is made of muscle and connective tissue and is the thickest layer.
The third layer is connective tissue, mostly collagen and keeps the arteries
from injury. If the arteries are damaged blood may come between the layers and
cause them to come apart. This is called an aneurysm. Aneurysm causes the
layers to come inward and reduce the opening so the blood flow is reduced to an
organ. Sometimes there is pain with aneurysm and sometimes there are no
symptoms. When an aneurysm ruptures it causes internal bleeding and usually
results in death.
An aorta is
the largest artery and the smallest is arterioles. Because arterioles are
further from the heart the blood pressure is not as high in them as in the
aorta. Because the blood pressure is not as high they usually do not have the
third layer, the layer of connective tissue. Arterioles also have a job that
aorta do not, releasing the correct amount of blood into capillaries.
Capillaries
Capillaries
are also a type of blood vessel and they are the smallest blood vessel. They
have thin walls and are only a tiny bit bigger than red blood cells.
Capillaries are arranged together in capillary beds over the entire body. Blood
is able to trade out oxygen, carbon dioxide, nutrients and waste products with
tissue because of the thin way capillaries are made. There are opening to allow
certain fluids to be traded but keep red blood cells and plasma in them. There
is an extra amount of fluid during this which is placed in lymphatic capillaries.
Lymphatic capillaries are classed in the lymphatic system. They take the extra
fluid and deliver it to larger vessels which will bring the fluid to a vein
near the heart.
Veins
Blood returns
to the heart from veins. Veins have three layers but are not as thick as
arteries. The blood is on its way back to the heart so the blood pressure is
not as high as it was on its way out, meaning the veins are able to serve their
function with a thinner wall. Veins fight against gravity to return blood to the
heart. In cases of people who spend a lot of time on their feet, they may
develop varicose veins in their legs and feet. This happens from blood pooling
in certain areas. Veins are intertwined between muscles. When we move the
muscle presses against the veins and helps push it back to the heart. If you
are inactive for a while you may become tired easily. This is due to blood
pooling in your legs. When you are active it helps the blood return to the
heart. Veins also have valves that only allow blood to flow to the heart. It
the blood tries to travel the wrong way, they will close off. Breathing also
causes pressure against veins helping to push the blood through to the heart.
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| (Anatomy of the Human Heart) |
The
Heart
The heart is
made mostly of cardiac muscle and does not need to connect to bone. Its job is
to continually be pumping so that blood is moved through the body. Your heart
does not stop beating for longer than 2/3 of a second at any time. The brain
normally gives the heart instructions on how fast it should be pumping but it
can function without the brain giving it instructions. The heart is surrounded
by the pericardium which helps keep the heart safe, keeps it in place and keeps
it from being filled with too much blood. Between the heart and the pericardium
is the pericardial cavity which has lubrication so that there isn’t any rubbing
between the heart and pericardium.
The heart is
made of three layers. The epicardium is the outer layer and is made of
epithelial and connective tissue. The next layer is myocardium and is mostly
thick cardiac muscle which contracts when the heart beats. The most inner layer
is the endocardium which is endothelial. Any of these three layers may become
inflamed and may be treated with antibiotics or anti-inflammatory medication
depending on the cause.
The heart
also has four chambers and four valves. The top two champers are called atria
and the bottom two are called ventricles. The septum divides the right and left
sides of the heart. The ventricles are more muscular than the atria. When blood
is coming back into the heart in enters through the right atrium. It then goes
through a valve to the right ventricle where it is pumped into an artery that
goes to the lungs. Blood comes back into the heart from the lungs by going into
the left atrium and then going through another valve into the left ventricle.
The left ventricle pushes the blood into the aorta through the fourth valve.
The blood travels throughout the body and then returns to the right atrium to
begin again. The valves prevent the blood from traveling in the wrong
direction. There are atrioventricular valves between the atria and ventricle on
both the right and left sides and semilunar valves between the ventricles and
arteries.
Because the
heart requires so much blood it has its own blood vessels called the coronary
arteries. If these arteries become blocked it can result in serious health
problems.
Pulmonary
Circuit
The process
that the blood goes through is as follows. First it goes into the right atrium
from the veins. It contains carbon dioxide. The blood goes through the right
atrioventricular valve and enters the right ventricle. It then enters the
pulmonary semilunar valve and passes into the pulmonary trunk which goes into
the lungs. When the blood reaches the pulmonary capillaries it releases the
carbon dioxide and receives oxygen. The blood goes through the pulmonary veins
that go back to the heart. It enters the heart through the left atrium and goes
into the left ventricle by passing through the left atrioventricular valve. The
blood without oxygen on the right side of the heart and the blood with oxygen
on the left side never mix together.
Systemic
Circuit
After the
blood goes through the pulmonary circuit, it goes through the systemic circuit.
The blood goes from the left ventricle into the aorta. It travels into the
branching arteries throughout the body into the capillaries. Once it reaches
the capillaries, it delivers oxygen and nutrients to the tissues and takes up
waste products. Then the blood enters the veins and travels back to the right
atrium and begin the pulmonary circuit again.
The Immune System
Pathogens
Pathogens are
bacteria, viruses, fungi, protozoa, prions and parasites that can cause
disease.
Bacteria are
the most abundant organism. Bacteria do not have a nucleus or membrane bound
organelles and are single celled. The DNA is found in one chromosome in most
bacteria and makes a repeated loop and is attached to the plasma membrane.
There are good bacteria and bacteria that cause illness. Good bacteria can be
made to make antibiotic medication, hormones, vaccines and even some foods.
Some good bacteria live in the digestive tract and helps make vitamins and keep
out harmful bacteria. Some bacteria are pathogens and damage or kill cells.
They cause a variety of illness. These illnesses can usually be treated with
antibiotics which stop them from growing.
A virus
consists of one small piece of RNA or DNA and is encircled by a covering of
protein. They don’t have an organelle, so they don’t reproduce or grow. Viruses
grow by entering a living cell and taking it over. Some viruses are extremely
serious or life threatening such as AIDS, hepatitis and encephalitis. Other
viruses make you feel lousy but are not serious such as colds and warts.
Prions cause
mad cow disease in cattle and variant Creutzfeldt-Jakeob disease in humans who
have eaten beef made from cows who have had mad cow disease. Prions are
misfolded brain cell protein and they can make the proteins around them misfold
as well. After a period of time there are enough prions that the cells burst and
the prions are able to attack other brain cells and neurological damage is
seen. Once you have contracted prions there is no cure available so it is
important to avoid eating beef that comes from cattle with mad cow disease.
Transmission
of Pathogens
Some
pathogens are transmitted very easily and others are harder to contract. The
common cold is very easy to catch but not usually serious. HIV is harder to
catch but is much more serious disease. If a disease is both serious enough to
be potentially life threatening and easily caught, it can result in an epidemic.
Biology
in the News
Scientists
believe they have found a way to detect pathogens that may cause inflammatory
bowel disease more quickly than they currently can. The method involves using
nanoparticles covered with DNA markers specific to certain pathogens. This
process only takes hours instead of weeks before it produces results. The
scientists made hybridizing magnetic relaxation Nano sensors that can find
minuscule amounts of DNA from pathogens that may be hiding. When the hMRS
attaches to the pathogen’s DNA a magnetic resonance signal is given and is made
louder by the water molecules that are around the nanoparticle. The results can
be read by a computer or smartphone by reading if there is a change in the
magnetic signature. (Florida)
(Sun Coast Seminars)
Lymphatic
System
The lymphatic
system has three main jobs. The first is it maintains the amount of blood in
the cardiovascular system, it carries fats and fat soluble vitamins from the
digestive system to the cardiovascular system and it fights off infections. The
lymphatic system is made up of the lymph nodes, spleen, thymus gland, tonsils
and adenoids. They can take in elements that are too big to enter a capillary.
They contain fluid called lymph and it is made from white blood cells,
proteins, fats and sometimes bacteria or virus. Lymphatic capillaries come
together to make lymphatic vessels. They are similar to veins in that they are
made of three layers and have valves that keep the lymph from flowing in the
wrong direction. The flow of lymph is also helped along by contracting muscles
during movement and by breathing. The lymphatic vessels come together until
there are enough of them to make two large vessels. These two vessels are
called the right lymphatic duct and the thoracic duct. They combine with veins near
the shoulders so the lymph is able to go back to the cardiovascular system.
Lymph Nodes
Lymph nodes
are found at spots by the lymphatic vessels. Their function is to remove
microorganisms, cellular debris and damaged cells from the lymph before it goes
back in the cardiovascular system. Lymph nodes are found in the digestive
tract, neck, armpits, and groin. They are surrounded by connective tissue and
have connective tissue and two kinds of white blood cells, macrophages and
lymphocytes, inside them. The white blood cells remove microorganisms from the
lymph. The lymphatic vessels bring the lymph to the nodes where it goes in and
out of them. There are valves to make sure the lymph goes in the correct
direction. As the lymph goes in the node, the macrophages kill unknown cells by
phagocytosis and the lymphocytes turn on defense mechanisms.
The Spleen
The spleen is
the biggest lymphatic organ. It is found in the upper left abdomen. It is
surrounded by a capsule of connective tissue with muscle cells scattered
throughout. Red pulp and white pulp are found inside the spleen and are types
of tissue. The spleen has the jobs of removing old and ruined ted blood cells
and fighting infections. Macrophages are found in the red pulp and they destroy
microorganisms and old or damaged red blood cells. The blood is kept in the red
pulp so it is available if you have a need for more blood. Lymphocytes are
found in the white pulp and they look for unknown pathogens. Some diseases
cause the spleen to become enlarged and it can rupture if it is hit. Surgery is
necessary to prevent hemorrhage and the spleen is removed. A person can live
without their spleen because there are other organs that have the same
jobs.
Thymus Gland
The thymus
gland is found just above the heart. It is surrounded by connective tissue and
holds lymphocyte and epithelial cells. It produces the hormones thymosin and
thymopoietin. The younger a person is the more this gland works to make the
defense system strong. As a person grows older this gland shrinks and may even
eventually disappear if it is no longer needed.
Tonsils
Tonsils are
made of lymphatic tissue and are found in the throat. Tonsils take out
microorganisms that enter the throat. The sometimes become infected and have to
be taken out by surgery. Adenoids are also lymphatic tissue and are found
further back near the nasal. They usually begin to shrink when a person reaches
5 years old and eventually disappear. Sometimes adenoids are large enough that
they block the airflow and may need to be surgically taken out.
First
Line of Defense Against Pathogens
The skin is
the first defense that pathogens come up against. Skin is made up of four main
features that help it be a good defense. The first is the protein keratin that
is found in skin. The second is that new skin is always being made when old
skin dies away. The third is that skin has a low pH so it is not a good
environment for unknown cells. And the fourth is that sweat glands make an
antibiotic called dermicidin that fights off bacteria. It is easier for
pathogens to enter through places where there is no skin covering. To make it hard
for pathogens to enter through the eyes, we have tears that can wash them away.
Saliva is a defense system to keep pathogens from entering through the mouth.
Saliva and tears have an enzyme that destroys some bacteria called lysozyme.
The ears make earwax that microorganisms become stuck in. The body also
produces mucus in which microorganisms stick to. The digestive acid is the
stomach is so strong there is only one type of bacteria that can survive in the
stomach, H. pylori. The body also produces vaginal acids that are acidic but
they are not as strong as the stomach acids. The body can get rid of some
pathogens through vomiting, urinating and defecation.
The
Second Line of Defense
White
Blood Cells
If a pathogen
is able to get past the first line of defense, they will begin to destroy
cells. If this happens nonspecific defense system will begin to work to
identify and fight off the pathogens. The white blood cells, phagocytes are
part of that system. They grab bacteria and surround it. Once it is surrounded,
lysosomes that contain enzymes do away with the bacteria. Neutrophils are also
white blood cells that do away with bacteria and also some fungi. Macrophages,
yet another white blood cell, fight off virus and bacteria parasites. If the
pathogen is too big for these to digest it, the white blood cells eosinophil
will fight it by circling the pathogen and throwing enzymes at it.
Inflammation
Inflammation
is a line of defense for tissue that has been damaged. During this process
there is redness, warmth, swelling and pain due to what is happening to stop
the damage from spreading and to repair the tissue. The cells that have been
hurt give of chemicals that let the body know to start the inflammation
process. Connective tissue called mass cells let out histamine which causes the
blood vessels that are nearby to widen. This brings more blood into the injured
area which causes it become red and warm. It also causes leakage into tissue
which causes swelling. Clotting proteins make a fibrin mesh to keep the injured
tissue away from the healthy tissue. The swelling causes there to be pressure
to nerve endings resulting in pain.
Natural Killer Cells
There are
white blood cells referred to as natural killer cells and they attack tumor
cells and viruses. They give off chemical that destroy the cell membranes they
are attacking.
Complement System
The
complement system is made up of 20 plasma proteins that complement other
defense systems. They travel though the body until they are needed then they
are turned on and turn others on in a chain reaction. They come together to
make a large protein that can make holes in the bacteria. Then fluid and salts
seep in until the bacterium grows so large it bursts.
Interferon
When a virus
takes over a cell the protein interferon goes to cells that are nearby that are
healthy and causes them to make proteins that stop the virus.
Fever
When
macrophages realize there is pathogens they release pyrogens which cause your
body temperature to go up. This makes the body a less friendly place for the
pathogen and also helps speed up the defense system and tissue repair.
The
Third Line of Defense
Antigens
The third
line of defense is the immune system. The immune system fights off antigens.
Antigens are substances that cause the immune system to turn on. Antigens are
large proteins or polysaccharide molecules. The each has a different shape. The
immune system makes a certain antibody to attack the antigen. It makes the
certain antibody based on what shape the antigen is. Antigens are found on the
outside of a cell so the immune system is not able to tell there is a virus
once the virus is inside a cell. A persons cells contains major histocompatibility
complex proteins that lets their immune system know that these cells belong and
not to attack them.
Lymphocytes
Lymphocytes
are white blood cells. There are two kids, B cells and T cells. B cells grow in
bone marrow and T cells in the thymus gland. B cells make antibodies that fight
antigens. T cells attack unknown cells that have antigens. There are five
groups of antibodies. The largest group is IgG and is located in the blood,
lymph, intestines and tissue. They are able to enter the placenta during
pregnancy and the baby will be born with some of the mother’s immune system.
IgM antibodies are located in the blood and lymph. They turn on the complement
system when needed. IgA antibodies are found in areas where there are mucous
membranes. They counteract pathogens and are found in breast milk, another way
a mother’s immune system is passed on to her infant. IgD antibodies are located
in blood, lymph and B cells and their job in unknown. IgE antibodies are
located in B cells, mast cells, and basophils. They let out histamine during
times of inflammation. They are also responsible for allergic reactions.
Antibodies are made so that they are able to target a certain antigen.
Immune
Memory
Once the
immune system has fought off a certain antigen B and T cells make memory cells.
These cells create immunity from that disease. Each time you are exposed, it
takes less time for the immune system to fight off and destroy the pathogen so
you may not even feel sick. Some cells last a lifetime, some need to be
reactivated.
Medical Assistance in
Fighting Pathogens
Immunizations
The basis
behind immunizations is to expose the body to an antigen so the immune system
will initiate a primary response then if a person is exposed again to the
antigen, memory cells will kick in and quickly fight it off. There are also
passive immunizations in which a person if injected with antibodies that their
immune system has not had time to make. Antibodies have been cloned and are
called monoclonal antibodies. They are used to test for pregnancy, prostate
cancer, hepatitis, influenza and HIV/AIDS. Antibiotics are another way medicine
can help fight pathogens.
Inappropriate
Immune System Activity
Allergies
A person
develops allergies when the immune system acts as if the allergen were a
pathogen even though it is not.
Autoimmune Disorders
Autoimmune
disorders happen when the immune system goes after its own cells. Lupus
erythematous is one type of autoimmune disease. This disease attacks connective
tissue. It is much more common in women than men. Rheumatoid arthritis is
another autoimmune disorder. It causes imlommation in the synovial membrane
that is found in joints. It kills joint cartilage and the bone and eventually
causes deformations.
There is no
cure to these inappropriate immune system responses.
 |
| (Respiratory System) |
The Respiratory System
Respiration
Respiration
includes four functions. Breathing is when air moves in and out of the lungs.
External respiration refers to gases between inhaled air and blood being
traded. Internal respiration is when gases are traded between blood and tissue.
And cellular respiration is when oxygen is used to make ATP in cells.
Respiration also helps to produce sounds in humans and animals.
Upper
Respiratory System
The
respiratory system is divided into the upper and lower respiratory tracts. The upper
respiratory tract is made up of the nose and pharynx. Nose enters into the body
through your nose or mouth as you inhale. The nose also gives you a sense of
smell, filters some foreign objects that are inhaled, provides moisture and
warmth to air, and gives your tone to your voice. The external nose is the part
you can see. The inside is the nasal cavity. They are made into 2 chambers by
the nasal septum. Air enters through your nostrils then enters into the nasal
cavity. There is epithelial tissue surrounding the cavity. This warms up the
air and provides mucus that can trap foreign objects so they don’t get any
further into the respiratory tract. There are tiny hair like things called
cilia that move the mucus to the back of the nasal cavity. We expel it by
coughing it up or swallowing it. In cold weather they do not move as fast which
is why people’s noses run when they are cold. Then the air comes into the
pharynx, the throat. The pharynx connects to the larynx and the air will enter
the lower respiratory tract.
Lower
Respiratory Tract
The parts of
the lower respiratory tract are the larynx, trachea, bronchi and the lungs. The
larynx jobs are to keep the airway open, make sure the food and air go into the
right places, and help produce sound. It is made up of the epiglottis and vocal
cords. The epiglottis is a flap at the opening of the larynx. When air is
coming in it stays open. It closes when we swallow food. This keeps food and
liquids from going into the trachea. Vocal cords are connective tissue. Most of
the sounds we make are by the vocal cords vibrating. Your tone is affected by
how tightly stretched your vocal cords are. Next air reaches the trachea,
commonly referred to as the windpipe. It is made of c shaped cartilage that is
kept together by connective tissue and muscle. The lining of the trachea is
cilia and epithelial tissue. The mucus again traps any foreign objects that
have made it that far. The cilium moves them away from the lungs. If an object
becomes stuck in the trachea, choking occurs. Next the airway becomes two
sections, the right and left bronchi. These keep dividing into smaller and
smaller bronchi. The smaller bronchi have less cartilage. The smallest airways
do not have any cartilage and are made from a layer of smooth muscle that is
surrounded by connective tissue. Bronchi have other jobs than just moving air.
They help clean the air, help warm it up so it is the same as body temperature
and soak it with water vapor. Next air enters into the lungs where the exchange
of gases occurs. The lungs are made of connected airways and at the end are 300
million tiny sacs that are filled with air and called alveoli. The alveoli are
where the exchange of gases takes place. Blood in the pulmonary capillaries
comes very close to the air in the alveoli.
Breathing
Process
Lungs do not
have any skeletal muscle so they need the bones and muscles around them to make
them expand. The bones and muscles that help in this process are the ribs,
intercostal muscles that are located between ribs, and the diaphragm.
(Visible Body)
Gas
Exchange
When blood
enters the capillaries, oxygen spreads from the capillaries to interstitial
fluid. Carbon monoxide spreads the other direction; it goes from the cell to
the interstitial fluid to the capillaries. Oxygen is carried in the blood by
binding to hemoglobin in red blood cells or it dissolves into plasma. 98% of
oxygen is carried in the blood by binding to hemoglobin.
The
Nervous System Regulates Breathing
Skeletal
muscles control breathing and skeletal muscles are turned on by motor neurons
which mean the nervous system controls breathing. The nervous system controls
the rate and depth so that there is homeostasis in certain things like CO2,
H+ and O2. We can consciously control are breathing if we
chose to a certain extent.
There is an
area called the respiratory center in the medulla oblongata which is located in
the base of the brain. The respiratory center is made up of nerve cells that
give of electrical impulses. These impulses travel to the diaphragm and the
intercostal muscles and cause them to contract. The rib cage expands and the
diaphragm goes down and we are able to inhale. When the impulse is over, the
muscles relax, the rib cage goes back to normal, the diaphragm goes back up and
we exhale. The rate and depth of breath are controlled by the requirement to
get the CO2 out. We can override this system and control our
breathing for a short period of time. However, the regulatory mechanisms will
overpower our will if we are providing out bodies with the breath it needs.
Respiratory
Disorders
Disorders
that Impede Respiratory Function
Asthma is a
respiratory disorder that is causes by the bronchial muscle spastically
contracting, bronchial swelling and more mucus than usual being made. The
bronchi close partway so it is difficult to breathe. It is a chronic condition.
There are medications to help open the bronchi and reduce the swelling. Finding
out what is the cause the attack and avoiding triggers is also helpful.
Emphysema is
chronic disorder form damaged alveoli. Connective tissue to the small airways
is destroyed which makes the airways not stay open as they should and collapse
when expiration. This damages the alveoli which make for a reduced are for
gases to be exchanged.
Bronchitis
occurs when the bronchi becomes inflamed making a cough that produces more
mucus than normal.
Cystic
fibrosis is an inherited disease. It causes there to be thick mucus in the
lungs that affects the air flow through them.
Respiratory Disorders from Microorganisms
Colds and
flues are upper respiratory infections that are usually caused by viruses.
There is no cure for them and they are usually not dangerous. Occasionally they
can develop into a serious infection.
Pneumonia is
when the lungs become infected and cause the alveoli to make more fluid than
needed which gets in the way of the gasses being properly exchanged. Pneumonia
can usually be treated but sometimes can lead to death.
Tuberculosis
is a bacterial infection that causes coughing, chest pain, shortness of breath,
fever, sweat, loss of appetite and weight loss and damages the lungs.
Tuberculosis can be treated by antibiotics.
Botulisms
when you become poisoned by Clostridium botulinum, a bacterium. This is found
in food that hasn’t been fully cooked. It makes swallowing and talking
difficult, double vision, nausea and vomiting. It blocks nerve signals to the
skeletal muscles so you are unable to breath. Botulism will lead to death if it
is not treated.
Lung Cancer
Cancerous
cells push normal cells out of the lung and interfere with the air moving
through the airway and the exchange of gases. More than 90% of people with lung
cancer are smokers or former smokers.
Pneumothorax and Atalectasis
Pneumothorax
is when one of the lobes in the lungs collapses. It is life threatening and
treatment is needed right away. Atalectasis occurs when gas isn’t being
exhanged because the alveolar collapsed or fluid has built up in the alveoli.
It can be treated by reversing the cause.
Congestive Heart Failure
If the left
side of the heart doesn’t work properly it can lead to blood not flowing
through it and backing up, raising the blood pressure in the pulmonary vessels.
This causes fluid to in the interstitial space between capillaries and alveoli.
This leads to less spread of gases.
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