Download ANATOMY LECTURE Unit 2

LECTURE 8 (Muscular System)
MUSCULAR SYSTEM: Today’s material will not be on this exam.
Muscles have only one function; to contract.
Bend your arm (this muscle- biceps- is contracting). What happens if I relax? Nothing.
To extend the arm, I need another muscle. Therefore, you need lots of muscles for all the
complex movements of the body.
CROSS SECTION OF A MUSCLE
The MUSCLE FASCIA is loose fibrous connective tissue on the outside of the muscle.
It creates a slippery surface for muscles to rub against each other.
EPIMYSIUM is dense regular fibrous connective tissue, deep to the fascia, which
eventually becomes the tendon (which is connected to bone). It extends into the muscle
belly to form compartments. In this area, it’s called the PERIMYCIUM. Each
compartment has MUSCLE FIBERS, which are individual muscle cells. A bundle of
muscle fibers is a FASCICLE. When you eat steak and find it’s stringy, each string is a
fascicle, and the fat around the whole outside of the slice of meat is where the fascia is.
Between the fascicles is the ENDOMYCIUM, which is loose connective tissue.
TYPES OF MUSCLES: Depends on the pattern of the fascicles.
1. PARALLEL MUSCLE is when the fascicles are parallel (plastic arm model with
biceps muscle). They are long fibers, which can contract to 75% of their length.
They contract a long way, but they are relatively weak, because there are
relatively few fascicles.
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2. PENNATE MUSCLES: three types:
a. UNIPENNATE (inside of plastic arm); the fascicles are short, but there
are more of them. They are stronger, but do not have the same length
contraction ability of the parallel muscles.
b. BIPENNATE (back of arm); they are stronger than unipennate.
c. MULTIPENNATE are the strongest; they are multi-tendon (biceps femoris)
3. CONVERGENT MUSCLE has more fibers than parallel, and contract a greater
distance than pinnate. E.g. deltoid muscle.
4. CIRCULAR MUSCLE (Spincter) is arranged in a circle, with a small area of
tendon on the sides. It allows closure of the eyes, mouth, etc. They are not very
strong, but they don’t need to be.
TERMS:
ORIGIN = The region which usually doesn’t move when the muscle contracts. Look at the
biceps brachii; does the shoulder move when I bend my arm? No; the shoulder = origin.
INSERTION= The point of attachment that moves; bend arm, radial tuberosity = attachment.
AGONIST = The main muscle for a particular action; bend arm, biceps = agonist.
SYNERGIST = The muscle that helps the agonist. There are several muscles that assist
when the arm is bent.
ANTAGONIST = Does the opposite action; bend elbow, antagonist extends. Every
muscle in the body has to have an antagonist.
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HOW MUSCLES MOVE BONES
Muscles move bone by acting like they are moving a lever (demonstrate a yardstick under
a weight). There are three types of lever systems:
1. FIRST CLASS LEVER: like a see-saw: force-fulcrum-weight. The fulcrum is
the point at which it moves (joint). When you bend your elbow, the weight is the
arm itself. In the neck, if there’s a muscle on the occipital process that contracts
and pulls the head up, where’s the joint? The atlas. The weight is the head.
If the distance from the fulcrum to the muscle is 4 cm, and
The distance from the fulcrum to the weight is 2cm, and
The weight of the head is 5kg,
How much force is needed to raise the head? There’s a formula for that:
FORCE x DISTANCE BETWEEN MUSCLE/FULCRUM
= WEIGHT x DISTANCE BETWEEN WEIGHT/FULCRUM
X(4cm) = 5kg(2cm)
4X = 10
X = 2.5 Kg
If the muscle contracts 1cm, how much will the head move? One more formula:
DISTANCE MOVED
DISTANCE OF MM CONTRACTION
=
DISTANCE OF WEIGHT/FULCRUM
X
1cm
=
2cm
DISTANCE BETWEEN MM/FULCRUM
=> 2 = 4X
=> X = ½ cm
4cm
The values change, depending on where the muscle is in relation to the fulcrum.
(Change the distance and do the math again)
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2. SECOND CLASS LEVER: Allows a lot of work with little exertion. Look! I’m
lifting my entire body weight on one foot! See how strong I am? Not really. I’m
using a second class lever, with the fulcrum at the ball of the foot.
Force-weight-fulcrum.
If the body is 60kg:
X(20) = 60(500)
X = 15 Kg force to lift 60 Kg person.
But nothing comes free. To lift the head 1cm, how many cm must the muscle contract?
1cm
X
=
5cm
=> 5x = 20 => x = 4cm
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To lift 1 cm, must contract 4cm. This muscle doesn’t need much strength, but it needs
length. What kind of muscle does it need? Parallel muscle.
3. THIRD CLASS LEVER: weight-force-fulcrum
If 30 Kg force is exerted on muscle, how much weight can be lifted? Do the math!
(By the way, there are no calculators allowed on the test).
30(10) = X(30)
300 = 30x
x = 10 Kg.
That’s a lot of force to move the arm.
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If the muscle contracts 5 cm, how much distance can it move?
X
= 35cm
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Therefore, a small contraction creates a large distance. What kind of muscles powers a
3rd class lever system? Multipennate.
Look at a door. Where’s the fulcrum? The hinge. Where’s the weight? Down the
middle. Push close to the door knob, this is 2nd class lever; don’t need a lot of force to
open. Push against door near hinge, that’s 3rd class lever. You need lots of force here,
but once you get it moving, the door moves a lot.
There’s a 10 point lever system problem on the next test.
Any questions about the material for this week’s exam?
NEXT LECTURE = EXAM I
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LECTURE 9 (Muscular System)
MUSCLE FIBERS (Muscle cells)
SKELETAL MUSCLE (20 mins)
Theses are very long fibers (biceps muscle can be 8-10 cm).
They have lots of nuclei (1,000’s of them).
They originate from stem cells, called MYOBLASTS, which fuse together to form fiber.
Myoblasts exist in adults, so damaged muscle is easily replaced; muscle tears heal well.
A muscle cell torn in half can regenerate two cells, like a worm.
There are almost no muscle diseases, because muscle can heal.
(Overhead picture of fiber, membrane, and bundles (myofibrils).
Straw holder is like a fascicle
Straws are myofibrils.
Each fiber has 1,000’s of mitochondria, so they also have SARCOPLASMIC
RETICULUM (like Smooth endoplasmic reticulum), which extend throughout the fiber,
the function of which is to store Ca++. The green straws are sarcoplasmic reticulum.
MONOFIBRILS are made of two types of filaments, arranged in a pattern:
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
ACTIN
MYOSIN
ACTIN
They form repeating patterns, giving the striped appearance of skeletal muscle (AKA
striated muscle). When a muscle contract, the actin and myosin move (but neither one
shortens; the sarcomere is what shortens).
A SARCOMERE is an actin/myosin unit.
Each myosin fibril has a head with filaments that connect to an actin fibril.
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For contraction to take place, need two things: nerve signal and calcium
Need a signal from a nerve (called an ACTION POTENTIAL). This action potential
goes through T-tubes to the sarcoplasmic reticulum, which causes Ca ++ to leak out of
the SR. Calcium binds to a protein on the myocin head (tryponintropomyecin), which
causes the protein to move out of the way so the two filaments can bind. Holding a
yardstick (actin), the hand holding it is the protein which is blocking where the other
hand wants to hold the stick. Free hand is myocin. The calcium makes the hand
(protein) move out of the way so the myosin can contact the actin. After a while, the
calcium gets pumped back into the sarcoplasmic reticulum, the proteins move back into
position, and the muscle will relax.
TWITCH = single muscle fiber contraction (takes 1/20th of a second).
How is it that I can pick up and hold a chair if the fiber only contracts for 1/20th second?
There are lots of fibers per muscle (10s of thousands), each one contracting at different
intervals, so contraction is maintained, just like tug-of-war. One person in ten can drop
the rope and get a better grip because the others are maintaining the tension.
(10 mins)
In a muscle, there are 1,000s of fibers.
A MOTOR UNIT is a single neuron and all of the muscle fibers on which it synapses.
If one neuron sends a signal, only its muscle fibers contract (the motor unit). This allows
for strength variations in lifting a chair vs. an eraser. For full strength, all the motor units
contract. For half strength, half of the motor units contract.
There are 6 motor units in this diagram; that allows for 6 different levels of contraction.
The more motor units there are, the more precisely the muscle can respond.
The muscles of the back are larger motor units, but there are fewer of them = strength,
but less precision. The muscles that move the eye are smaller motor units (10 fibers per
neuron), but there are many motor units present = less strength, more precision.
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Muscles also respond to forces:
Exercise  HYPERTROPHY (growth in size); can happen in two ways
1. Increase in number of fibers
2. Increase in size of individual fibers
Lack of use  ATROPHY. This happens quickly. Astronauts can lose 40% of their
muscle in two weeks! It is regained quickly, too. If a neuron is cut, muscle atrophies.
After exercise, you can get sore…why? It’s not from lactic acid build-up; muscle is torn.
Strength training should be done every day. No Pain – No Gain is a fallacy. You can
gain strength and size without pain. Eating protein also does not increase muscle. The
average person only needs one ounce of protein a day, two if you work out. Two ounces
is like one mini hamburger. Most people eat too much meat.
MUSCLE DISEASE: MUSCULAR DYSTROPHY
This is a genetic lack of a protein called DISTROPHIN, which attaches actin and
myosin filaments to the plasma membrane. The cell won’t contract = paralysis, even
though the actin and myosin are working.
SMOOTH MUSCLE (20 mins)
Found around internal organs, blood vessels, bladder, GI tract, around the tubes to the
lungs. AKA involuntary muscle. You don’t say, “Gee, I think I’ll move something
through my small intestine now”. The actin and myosin are not as organized, so you
don’t see striations.
Characteristics of smooth muscle
1. Twitch time is very long = several seconds
2. It doesn’t get tired (“I’m too tired to urinate!”)
3. Contracts in response to neurons as well as hormones and changes in local
environment (amount of oxygen, lactic acid, etc).
CARDIAC MUSCLE: Only found in heart. Has both smooth/skeletal characteristics.
It is made up of individual cells.
The actin and myocin are organized: it’s strong and striated.
There are INTERCALATED DISCS which join each cell. These are a series of gap
junctions (communication) and desmosomes (holds cells together).
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As one cell contracts, the action potential goes through all the cells, and they all contract
as a unit. That’s why the heart contracts all at once.
4. It has an intrinsic beat. The cells contract on their own, without a signal.
Even if you chop a heart up, each piece will beat by itself!
CIRCULATORY SYSTEM (15 mins)
FUNCTIONS:
1. Transport (nutrients, wastes, oxygen, CO2, homones0
2. Immunity (leukocytes, antibodies)
3. Temperature regulation (cold, constricts; hot, dilates)
4. errection
COMPONENTS OF CIRCULATORY SYSTEM
1. Blood
2. Heart
3. Blood vessels (arteries, capillaries, veins)
4. Lymph vessels
You have about 5 liters of blood, but that is only half of the body fluid. The other half,
which includes Extracellular fluid, synovial fluid, etc, are in contact with blood.
PLASMA  EXTRACELLULAR FLUID
↑
↓
SYNOVIAL FLUIDS, ETC
PLASMA CONTENTS
1. Water (90%)
2. Dissolved substances (10%)
a. Proteins
i. Albumin (egg white). Most common protein in blood (homeostasis)
ii. Antibodies
iii. Clotting factors
iv. Lipoproteins (move fats through blood: HDL, LDL)
b. Nutrients
i. Glucose (main energy source)
ii. Amino Acids (builds proteins)
c. Wastes (urea)
d. Gases (O2, CO2, Nitrogen)
e. Electrolytes = ions (Na+, K+, Cl-, Ca++)
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LECTURE 10 (Cardiovascular System) CIRCULATORY SYSTEM (cont’d)
CELLS OF THE BLOOD (15 mins)
1. ERYTHROCYTES: These are among the smallest cells in the body. There are
about 5 million of them in each of us. Their structure is simple; like a doughnut
with the hole not fully cut out.
a. They have no nucleus
b. Filled with hemoglobin, which carries O2 throughout the body.
Oxygenated Hb is bright red, deoxy Hb is dull red.
c. Average life span is 120 days. Old ones are destroyed in the spleen and
liver, and Hb is recycled. During your lifetime, about 250 billion of these
cells are destroyed, and 250 billion are made: where? Red marrow.
2. LEUKOCYTES: There are different kinds; all fight infection.
a. NEUTROPHILS: The most common type (picture). They are the first to
respond to infection. They phagocytize (eat) bacteria.
b. BASOPHILS: Few in body. Their blue granules are filled with
histamines, which help fight infection by vasodilation, increasing the
number of WBCs to the infection site. When a basophile leaves the
circulation to enter the tissues, it becomes a MAST CELL.
c. EOSINOPHILS: Function to fight allergies and parasitic infections.
d. MONOCYTES: Enter the tissues and become MACROPHAGES.
e. LYMPHOCYTES
i. B CELLS: Make antibodies (proteins that fight infection)
ii. T CELLS: coordinate the immune response. This is the cell that
is attacked by the HIV (AIDS) virus.
3. PLATELETS (compare their small size to others). These are pieces of another
cell found in the red marrow called a MEGAKARYOCYTE. Pieces break off of
a megakaryocte and are known as platelets. When a platelet encounters a broken
blood vessel it releases a substance that clots blood. Platelets are responsible for
clot formation.
HEMATOPOIESIS: The making of blood.
The plasma proteins are made in the liver.
The blood cells are made in the red marrow.
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STEM CELLS IN THE RED MARROW
1. ERYTHROBLASTS, which mature into RETICULOCYTES, which lose their
nucleus and gain more Hb to become ERYTHROCYTES, which are released
into the blood. If the body makes too few erythrocytes = ANEMIA.
a. Causes of anemia include lack of iron, hemorrhage, lack of vitamin B12
(needed for cell division).
b. Characteristic sign of anemia: see reticulocytes in the blood (immature red
blood cells. It’s better to send a young cell with no weapons to the war
than to send nothing at all.
2. MYELOBLASTS: These are the stem cells that mature into the specific leukocytes.
Leukemia is cancer of the stem cells. See all these different types of stem cells?
That’s about how many types of leukemia there are.
THE HEART (20 mins)
The heart is the simplest organ in the body. It does only one thing: pumps blood. It beats
42 million times a year. It’s about the size of your clenched fist. (Show life-size model
of heart). Some of you have big fists, some have smaller fists. Its location is deep to the
sternum. Take your fist and place it on the sternum, then angle the bottom of your wrist
to the left. When you say the Pledge of Allegiance, your hand is not over your heart. It’s
not on the left, it’s in the center.
Layers of tissues around the heart:
1. PERICARDIUM: surrounds the heart (model heart in baggie). The function is
to lubricate the heart, so as it beats, it won’t rub against anything. The
pericardium is divided into two layers;
a. PARIETAL PERICARDIUM (outermost layer of heart). Two layers:
i. SEROUS LAYER (simple squamous epithelium). Watery fluid.
ii. FIBROUS LAYER (moderately dense fibrous connective tissue)
b. PERICARDIAL CAVITY (Between the two layers, where the serous
fluid is). Put fingers around heart in baggie).
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c. VISCERAL PERICARDIUM (aka EPICARDIUM) Outermost layer of
heart. It also has two layers:
i. SEROUS LAYER
ii. FIBROUS LAYER
2. MYOCARDIUM: The heart muscle itself, made of what tissue? Cardiac muscle.
3. ENDOCARDIUM: The lining on the inside of the heart. Has two layers:
a. ENDOTHELIUM (simple squamous epithelium that provides a smooth
surface for the blood to pass by)
b. Loose fibrous connective tissue (deep to the endothelium)
PERICARDITIS: inflamed outer layer of heart.
Fluid accumulates in pericardia cavity, putting pressure on heart  improper beat
Damage to the blood vessels  blood leak into pericardial cavity  pressure  improper beat
ENDOCARDITIS (more serious):
Bacteria enter bloodstream (dental procedures, IV drug abuse, catheter)  damage to
lining and valves  blood clots.
Those who already have damaged heart valves need prophylactic antibiotics.
THE HEART IS TWO PUMPS: LEFT AND RIGHT (10 mins)
LEFT PUMP: From lungs to body
RIGHT PUMP: From body to lungs
Each pump has two chambers: ATRIUM and VENTRICLE
Deoxy blood from body enters the RA through the sup and inf vena cava.
It pours through the TRICUSPID (RIGHT AV) VALVE into the R ATRIUM.
R Atrium contracts, pushes blood into the ventricle  ventricle expands, then contracts
with force. To prevent the blood from going back up into the atrium, need a valve.
VALVES
Valves are like a swinging door that can only open one direction. But you can push
against this door, since it’s only tissue. But if you tie a rope to the doorknob, it won’t be
able to go the wrong way. Rope = CHORDAE TENDONAE, which is attached to
pieces of myocardium called CAPILLARY MUSCLES. The contraction pulls on the
chordae tendonae to close the valves, preventing a PROLAPSED VALVE (turned inside
out).
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With the ventricular contraction, blood can go only one way: into the PULMONARY
ARTERY (the only artery with deoxy blood). When the ventricle relaxes, the
PULMONARY SEMILUNAR VALVE prevents blood from going from the pulmonary
artery back into the right ventricle. Does it have a chordae tendonae? No; the blood is
not being forced back, it just falls back, so there’s not as much pressure.
Blood then goes into lungs, gets oxygenated, and returns on the left side through the
PULMONARY VEINS (the only veins with oxy blood), into the LEFT ATRIUM, and
down through the MITRAL VALVE (BICUSPID VALVE) into the LEFT
VENTRICLE, which contracts (with chordae tendonae), goes past the AORTIC
SEMILUNAR VALVE, into the AORTA, and back to the body.
SUMMARY OF BLOOD FLOW
Deoxy blood  sup/inf vena cava  R atrium  tricuspid valve with chordae tendonae
 R ventricle  pulmonary semilunar valve  lungs  pulmonary veins  Left atrium
 mitral (bicuspid) valve with chordae tendonae  aortic semilunar valve  aorta 
rest of body.
HEART BEATS (10 mins)
The left and right ventricles contract at the same time = SYSTOLE.
When the ventricles are relaxed = DIASTOLE.
At which stage do the atria contract? Diastole.
Start of Systole: Closing of valves (tricuspid and mitral) = sound
End of Systole: Closing of semilunar aortic and pulmonary valves = sound
Lub-Dub is the sound of the closing of the valves.
If the valve leaks, it doesn’t close properly = HEART MURMUR = Lub-squirt.
Most murmurs are benign; fairly common, esp. in babies and some adults.
PROLAPSED VALVE is more serious.
Mitral valve is most likely to prolapse because it pumped the hardest. See how much
more thick the lining of the left ventricle is? Might need artificial valve.
What controls the heart beat?
There is a small region in the right atrium = SA NODE (Sino-atrium node) = pacemaker
of the heart. Its job is to speed up or slow down the heart rate as needed. SA node sends
an electrical signal (action potential) to the AV NODE  atrium contraction pauses 
transmitted to both ventricles via conduction of myofibers  sends the action potential to
all parts of the heart so it can contract.
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We can see these electrical signals on an EKG. (Atrium and Ventricular contractions).
ARRHYTHMIA = problem with the SA or AV node  improper heart beat.
Treatment is medicines or a pacemaker.
THE HEART NEEDS ITS OWN BLOOD/O2 (15 mins)
The endocardium gets O2, but not the myocardium.
The blood vessels for the myocardium = CORONARY ARTERIES and VEINS.
They are on the surface of the heart (picture).
The more you exercise, the more branches you get. Some may ANASTOMOSE = two
vessels that meet. Blockage in the coronary arteries is a big problem.
HEART ATTACK
Not enough blood to the heart  severe pain  ANGINA.
Complete blockage  not enough O2 to that area = ISCHEMIA  that part of heart
muscle dies = MYOCARDIAL INFARCTION. Heart muscle never regenerates. If a
large area dies, person will die.
What are symptoms of a heart attack? Chest pain, pain down left arm, shortness of breath,
nausea, tight pressure in chest. A common symptom is death. 50% of first heart attacks
are fatal. About ¾ million people die each year from heart attacks.
Reasons for blockage
ATHEROSCLEROSIS = build-up of fat inside artery  narrowing of artery 
Spasm shut or blood clot. If clot is big, it can break off and go to the lungs.
But even a small clot can be a problem. It can block the conduction of the signal of the
AV node  FIBRILLATION (wiggle fingers) = VENTRICULAR FIBRILLATION.
The muscle doesn’t contract as a unit.
Treatment is defibrillate with electric shock  closes down heart  maybe it will restart.
Original problem is not treated, so it may not work, but it’s worth a try! There are three
on campus.
For a narrow artery, you can do a CORONARY BYPASS. Take another blood vessel
graft (from thigh) and go around the blockage. For double or triple bypasses, that’s how
many vessels are affected.
People who exercise have the same number of heart attacks as those who don’t, but they
tend to survive them.
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LECTURE 11 (Cardiovascular System)
EMBRYONIC DEVELOPMENT OF THE HEART (20 mins)
The heart is the most common site for congenital defects (those one is born with).
During fetal life, the mother provides the oxygen and nutrients through the placenta.
If there is a problem with the baby’s heart, it is not seen until birth.
At 21 days (one week after a woman misses her period), there are two muscular tubes.
At 23 days, the tubes begin to fuse.
At 25 days, the heart has formed; it has only two chambers.
Over the next 10 days, the bottom of the heart twists 180˚, and the septum develops to
divide the left and right sides of the heart.
By day 35, the heart is fully formed (only 3 weeks after the woman misses her period).
You have to stop smoking and drinking before you get pregnant. By the time you know
you’re pregnant, it’s too late for the baby’s heart.
Where is the fetus getting the oxygen during the nine months in the womb? The mother, not
the lungs. So there’s no sense in sending half of the body’s blood to the lungs for oxygen.
The lung tissue needs some oxygenated blood, but only a little. Therefore, there is an
opening from the right to the left atrium called the FORAMEN OVALE which shunts
blood from the right to the left side of the heart to bypass the lungs.
Another shunt is between the pulmonary artery and the aorta: DUCTUS ARTERIOSIS.
Therefore, there are two shunts to take blood away from the lungs.
At birth, there is an immediate change. Half of the blood needs to go to the lungs.
At the first breath, a flap closes over the foramen ovale, and a muscle around the ductus
arteriosis constricts, causing instant closing, and seals shut permanently.
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When a baby has not started walking, it doesn’t need as much oxygen, so a patent (open)
foramen ovale might not be noticed until they start to walk and run at age 2-3. A patent
foramen ovale can be surgically closed by going through the blood vessels without
cutting into the heart tissue. A patent foramen ovale in an adult is just a tiny opening and
can be heard as a heart murmur.
You can also have a patent ductus arteriosis.
More significant problems: ventricular septal defect (between right and left ventricle)
Requires open heart surgery. If heart is totally deformed, need transplant.
There are 100,000 miles of blood vessels.
With the exception of hyaline cartilage (which is Avascular), no cell is more than a few
cell diameters away from a blood vessel, so they can get oxygen, nutrients, remove waste.
All blood vessels (except the smallest) look similar.
BLOOD VESSELS (10 mins)
1. TUNICA INTIMA (“Coat”)
a. ENDOTHELIUM: simple squamous epithelium. Allows for smooth
flow of blood. Similar to endocardium.
b. SUBENDOTHELIUM: loose fibrous connective tissue.
2. TUNICA MEDIA
a. SMOOTH MUSCLE (allows vasoconstriction). Allows blood to be
directed to parts of body.
b. ELASTIC FIBERS: within smooth muscles. Allows blood vessels to
return to normal size, and to stretch during systole.
3. TUNICA ADVENTITIA (TUNICA EXTERNUM): dense fibrous connective
tissue which thins out to loose fibrous connective tissue.
a. Protects the blood vessel (strong)
b. Gives vessel strength for shape
c. Anchors vessel to surrounding tissue; loosens with age.
These layers are thick, so they need their own vascular supply: VASO VASORUM
(blood vessel for a blood vessel) to supply the oxygen. The endothelium layer does not
need this because it’s in direct contact with the blood, but the subendothelium needs it.
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TYPES OF ARTERIES
1. ARTERIES (10 mins)
a. ELASTIC ARTERIES: largest, closest to heart. Has to take the full
force of the systolic contraction; compensates by expanding a lot. There
of lots of elastic fibers in the tunica intima as well. Does blood flow
during diastole? Yes; elastic arteries return to original size, pumps blood.
This is another pump besides the heart.
b. MUSCULAR ARTERIES: with the exception of a few elastic arteries,
every other names or visible artery in a body is a muscular artery. They
range in size from 1/3mm on up. The difference is the size of the tunica
media. Thick ones are muscular arteries. Function is to distribute blood,
and help control which regions of the body get blood. When you are
exercising, you want the blood from the GI system to go to muscles.
When your hands are cold, you don’t want more blood going there or
you’ll lose heat; therefore, the vessels will constrict in the hands. Dilation
is just lack of constriction.
c. ARTERIOLES (microscopic; these are the smallest). Large ones look
like muscular arteries. Small ones only have two layers: endothelium and
tunica media. One of the characteristics of an arteriole is that when it
contracts, the arteriole closes completely.
Important:
You don’t have enough blood to go around; you only have 5 liters for 100,000 miles of
blood vessels. At any given time, most blood vessels will be closed (except at lungs).
Are you using your legs now? When your legs run low on oxygen, the vessels there will
open up again. Are you using your brain now? I hope so! The vessels there will be
open. When your leg falls asleep, there is pressure on an artery which stops the blood
flow. When the nerves are deprived of oxygen, they tingle.
(20 mins)
2. CAPILLARIES: These are the smallest vessels; 8-10µ; about the size of an
erythrocyte. They are the simplest; only have an endothelium. They are found
everywhere. There are three types:
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a. CONTINUOUS CAPILLARIES: found in all organs of body, made of
simple squamous epithelium. They have intracellular clefts, the function
of which is essential for plasma to leak out and bathe each cell with
Extracellular fluid, which is rich in oxygen and nutrients. Erythrocytes
and platelets don’t fit through, but leukocytes can squeeze through so they
can enter and leave the blood vessels as needed.
b. FENESTRATED CAPILLARIES (“window”). These have a lot more
leakage because there are more holes. Found in areas where lots of fluids
need to be moved back and forth (synovial membrane, small intestine).
c. DISCONTINUOUS CAPILLARIES (sinusoidal capillaries). These
have a big gap in the capillary. What can go in and out here? Anything,
including erythrocytes. These are found in red marrow. Why? That’s
where they are made, and they need to get to the lungs. They are also in
the liver and spleen, where red blood cells are destroyed.
3. VEINS: there are 2 varieties. A vein carries blood to the heart.
a. VENULE: this is the smallest. It takes blood from the capillary to the
vein.
b. VEIN: All veins are much thinner than arteries. There is no pressure in
veins, so they don’t need thick walls. Blood moves slowly through veins,
so lumen has to be bigger than an artery.
How does blood get uphill back to the heart? Veins need valves. Allows
blood to move in only one direction. What pushes the blood? The muscle of
the body constrict, squeezes the vessels. This is the third blood pump.
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BLOOD PUMPS
1. The heart
2. Elastic arteries
3. Muscles constricting the veins
LYMPHATIC VESSELS
1. LYMPHATIC CAPILLARIES: like regular capillaries; has endothelium and cleft.
2. LYMPHATIC VESSELS: looks like thin-walled veins; has valves.
You have a whole network of arteries
You have a whole network of veins
You have a whole network of lymph vessels
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LECTURE 12 (Cardiovascular System)
CAPILLARY BEDS
A network of continuous capillaries supply individual cells with oxygen, nutrients, blood, etc.
At the start of each capillary, there is a small muscle: PRE-CAPILLARY SPHINCTER,
which controls the flow of blood to individual capillaries. ARTERIOLES direct the blood
flow to the specific tissue. Pre-capillary sphincters direct the blood flow to specific cells. If
one cell is starving, the capillary next to it will open. The sphincter opens and closes
depending on the needs of individual cells.
Blood always flows to those cell and tissues that need it. There is not enough blood to go
around. Are continuous capillaries truly continuous? No, because fluid leaks in and out
of capillaries and are eventually reabsorbed into he veins. They drop off nutrients, pick
up CO2 waste, etc.
Imagine a pipe of water in this room, and a drain on the floor. Will all of the water drain
out? No. Not all of the interstitial fluid goes back into the blood; only 90% does. What
happens to the other 10%?
There’s another capillary bed within this area = LYMPHATIC CAPILLARIES.
They are closed-ended, and begin in the capillary bed. They are thin walled, and pick up
the interstitial fluid (called LYMPH). The lymph travels in vessels called…? Lymphatic
vessels. Eventually they dump the lymph back into the blood.
Network of lymph vessels (overhead)
Lymph vessels drain into the right thoracic duct near the clavicle.
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The capillary bed is a good place to protect the body from bacteria. We need structures
to help kill off bacteria: LYMPH NODES. There are hundreds of lymph nodes in the
body (dots on overhead). Each one clears bacteria and viruses, and they occur in clusters.
They have valves in them so it is always flowing one way; lymph can never back up.
The distribution of nodes is not uniform. There are large clusters in the axilla, neck,
inguinal region, and deep in the abdomen.
Medical personnel such as nurses, etc, need to know the lymphatic drainage pattern.
For example, from the breast, all the lymphatics go into the axilla, so that is where cancer
would spread first. It is detected by lymph node biopsy. If cancer is found, the surgeon
will have to remove all the lymph nodes from the axilla, and afterwards, there is no
lymph drainage for that arm, and there will be problems with swelling.
GIANT LYMPH NODES
In a baby, the THYMUS is the length of the sternum, and then it shrinks with age.
The SPLEEN is also a giant lymph node, with two functions. There are regions in the
spleen where there are sinusoids of discontinuous capillaries. The spleen is on the left
side of the body, at the costal margin. If it is enlarged (during an infection), you can
palpate it (feel for it).
In a car accident, the seat belt can break a rib, puncturing the spleen. You can’t stop the
bleeding…how can you sew a sponge together to make it stop dripping? The spleen has
to be removed. That’s ok; there are hundreds of other nodes, and the liver can take over
the function of weeding out the old RBCs.
TONSILS are also lymph nodes, but they can be removed if they are chronically
infected.
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CIRCULATORY DISEASE CONDITIONS
ARTERIOSCLEROSIS (“hardening of the arteries”). There are 3 types, frequently
found in combination:
1. ATHEROSCLEROSIS is fat in the elastic arteries. The subendothelial layer
is loose connective tissue with adipocytes. They cause the lumen to narrow, restricting
blood flow. In a coronary artery, it will cause ANGINA (heart pain). If the coronary
artery just goes into spasm, there’s not enough blood, causing a problem. Another
problem is that as fat accumulates, it breaks down the endothelium, and the platelets see
it and start a blood clot. A clot in an artery = THROMBUS. There will be no blood
flow distal to it  necrosis.
If this occurs in the coronary arteries  myocardial infarct.
If it occurs in a cerebral artery (brain)  stroke
In the USA, we start getting atherosclerosis by age 20.
It can be reversed.
Aspirin prevents blood clots.
2. HYPERTENSIVE ARTERIOSCLEROSIS
This is due to high blood pressure, where the blood vessels compensate by developing a
thicker wall. The vessels can no longer expand during systole, so the vessel gets thicker
and thicker, and the blood pressure goes up more. If the blood pressure gets too high, an
ANEURYSM can form, which is a weakening in the wall of the blood vessel. If it
ruptures, it’s very dangerous. That is the cause of 15% of strokes. The aorta is under
high pressure, so it is susceptible to rupture; you’ll be dead in three heart beats.
Aneurysms have no symptoms.
3. ARTERIOLE CALCIFICATIONS are calcium deposits in an artery, just
like in a bone, for unknown reasons. The blood vessel becomes hard like a rock; it can’t
expand or contract, causes increase in blood pressure. Diet and exercise don’t help much.
No one makes it through life alive. Everyone dies.
Cardiovascular disease or cancer kills most people.
The key is not to prolong life, but to prolong quality.
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EDEMA
This is an accumulation of fluid in tissues, caused by an imbalance of plasma leaving the
capillary vs. being absorbed by the lymph. This imbalance causes a lot of problems:
1. HEART FAILURE
If the heart isn’t pumping properly, blood won’t flow properly. When you
examine a patient, you press a thumb into their ankle…why? To see how long
it takes to bounce back. Try it on your arm. See the white circle? You have
squeezed the blood out. Now you count how many seconds it takes to return.
Why do this test on the ankle? That’s where gravity pulls the most.
2. PNEUMONIA
This is edema in the lungs. It is caused by congestive heart failure, bacteria, etc.
3. INFECTION
Whenever there is swelling with infection, that is edema. It is caused by
the body releasing histamines which make it easier for leukocytes to get
there. When you have a cold, you have edema in your nasal cavities, and
you can take an anti-histamine to treat it.
4. BLOCKING OF DRAINAGE
When you stand for a long time, there will be more fluid in the legs.
That’s why you should shop for shoes at the end of the day when your feet
are the most swollen.
Whatever the reason, as the swelling increases, it increases pressure on the nerves,
causing pain. It hurts the worst where tissues cannot expand. That’s why toothaches hurt
so much, and bone pain, too.
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LECTURE 13 (Cardiovascular System)
Reminder; the next exam is a week and a half away.
Meet next door after lecture if you want to go over the lever system problems.
(30 mins)
VARICOSE VEINS
An inflammation of the veins, usually due to lack of movement. What moves blood
through veins? Skeletal muscle. Surface veins don’t have skeletal muscles on top of
them. Also, the older and fatter a person is, the less squeezing of muscles there is on the
surface. Blood pools in the valves, and the weight of the blood distends the vein. Then
there’s even more blood pooling, and the vein can prolapse, getting even more blood
pooling, gets worse and worse.
Spider veins are so big they are actually visible. In the anus, a varicose vein is called a
hemorrhoid. People who sit with their legs crossed or stand for a long time can get
varicose veins. When you’re sitting, elevate the feet. When standing, shift your weight
from foot to foot. What helps these veins is weight loss, tight stockings. They are
unsightly, and may be painful, but are rarely serious.
They are serious when they are in the deep veins, because you can get a deep vein
thrombosis (DVT). What’s a thrombus? Blood clot. Usually caused by inactivity.
Called “Coach class syndrome”. Because blood stands still, can clot. It becomes very
dangerous when a piece breaks off = EMBOLISM. Can travel to the next smallest
vessel. If an embolism occurs in the leg, where is the next smallest blood vessel? In the
lungs: PULMONARY EMBOLISM. Can be fatal. DVTs are sometimes undiagnosed
if they are mild. One treatment of varicose veins is stripping (removing) the vein. Not a
problem because there are so many.
Look at your handouts of blood vessels. There will be a 10 point question on test about
tracing blood flow between any two parts of the body (e.g. from the left arm to the right
arm, the spleen to the pancreas, etc).
Blood vessels are named for where they are or where they go. The RADIAL ARTERY is
in the forearm, the GASTRIC ARTERY goes where? The ILIAC ARTERY is next to
the ileum, the FEMORAL ARTERY is in the femur, etc. There are a few that are
different:
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SUPERIOR MESENTERIC (small intestine)
INFERIOR MESENTERIC (large intestine)
CAROTID and VERTEBRAL (brain)
SUBCLAVIAN (below clavicle)
CELIAC TRUNK (branches off into the GASTRIC and HEPATIC arteries)
On the venous handout, the JUGULAR VEIN drains the head.
GREATER SAPHENOUS VEIN in the thigh is superficial, and frequently gets
varicosities, so it is expendable anyway; therefore it is commonly used for coronary artery
bypasses. No problem; there are plenty of others. Best choice is an artery, but not as many
can be spared.
MESENTERIC VEINS
GASTRIC VEINS
SPLENIC VEINS
↓
HEPATIC PORTAL VEIN
↓
LIVER
↓
HEPATIC VEIN
↓
INFERIOR VENA CAVA
↓
HEART
All of the blood from the GI tract and spleen
has to go through the liver before it gets
back to the heart.
Blood Flow from Left Leg to Right Leg (Always start with the venous system)
From left anterior tibial v  thigh (femoral or greater saphenous vein)  external iliac v
 common iliac v  inferior vena cava  right atrium  tricuspid valve  right
ventricle  pulmonary semilunar valve  pulmonary artery  lung  pulmonary vein
 left atrium  mitral valve  left ventricle  aortic semilunar valve  aorta 
abdominal aorta  common iliac a  exterior iliac a  femoral artery  anterior tibial
artery.
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Blood flow from Left Hand to Brain
Median cubital vein (same vein as when you give blood)  brachial v  axillary v
:subclavian vein + joins with jugular vein to form  brachiocephalic v  superior
vena cava  right atrium  tricuspid valve  right ventricle  pulmonary semilunar
valve  pulmonary artery  lung  pulmonary vein  left atrium  mitral valve 
left ventricle  aortic semilunar valve  aorta  left common carotid  Internal
carotid  brain.
(Or: aorta  brachiocephalic a  right common artery  internal carotid a  brain)
Pick two body parts!
Large Intestine to Large Intestine
Large intestine  superior mesenteric v  hepatic portal v  liver  hepatic v 
inferior vena cava  heart (describe details)  aorta  abdominal a  inferior
mesenteric a  large intestine.
RESPIRATORY SYSTEM (20 mins)
Main Function = gas exchange from O2  CO2
Other functions: speech (sounds) regulation of pH of blood.
1. NOSE: This is there because of a number of hyaline cartilages. It’s fairly
complex (show overhead with list of names of hyaline cartilages). Nose jobs
involve taking a mallet, breaking the nasal bone and shaving the cartilages.
2. NASAL CAVITY: The outer skin folds into the anterior nostrils (stratified
squamous epithelium); has hairs which filter large particles (insects, etc). Then
when you enter the nasal cavity, it’s lined by
a. NASAL MUCOSA (pseudostratisfied ciliated epithelium).
b. LAMINA PROPRIA (loose fibrous connective tissue) which has a lot of
mucous and serous glands. You produce one liter of fluid a day. There
are lots of veins in this tissue.
The functions of the nasal cavity is for the air you breathe:
1. Warm (cold air can freeze lungs); warmed by superficial veins
2. Clean (dirty air can clog lungs); mucous is sticky, and cilia will move
that dirt down the back of the throat, then it’s swallowed.
3. Humidify (dry lungs can crack). The fluid secreted by glands makes
the moisture, even on windy days the air goes to 100% humidity by the
time it gets to the lungs.
To make the nasal cavity function more efficiently, there are superior, middle, and
inferior nasal conchae, which cause to swirl the air around the nasal mucosa and
the lamina propria a few times before it gets to the lungs.
When you have a cold and get extra fluid (edema)  runny nose.
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The nasal cavity is connected to PARANASAL SINUSES (ETHMOID,
SPHENOID, FRONTAL, AND MAXILLARY SINUSES). They are also lined
with the same kind of mucosa. When you have a cold, you get stuffed up, and the
pressure can cause sinus headaches.
There is another connection: LACRIMAL DUCT to nasal cavity. There’s a hole
in the lacrimal bone. Excess tears drip down there. When you cry, you get a
runny nose. If the duct overflows, you see tears on face.
3. PHARYNX (three parts)
a. NASOPHARYNX: a continuation of the nasal cavity. The AUDITORY
TUBE is located here. It’s covered by the same type mucosa.
b. OROPHARYNX is the back of the mouth; visible when you open your
mouth and look all the way back.
Separating the oropharanyx and the nasopharynx:
1. SOFT PALATE: move your tongue along the roof of your mouth, and
going from the front to the back you’ll feel the hard part turning into a
soft part on the roof of your mouth.
2. UVULA: located at the end of the soft palate (seen in cartoons).
The function of the soft palate and uvula is to move upward when
swallowing, to prevent food from going into nasal cavities. When you vomit,
they don’t close, and food and stomach acids go into nasal cavity and cause problems.
c. LARYNGOPHARYNX: Stick out your tongue and say Ah! You’re
looking here. Can also see tonsils (lymph nodes) and vocal cords.
LARYNX (Show model) 15 mins
This is a very complex structure (show overhead).
It has two functions:
1. Produce sounds (vocal cords)
2. Prevent food from entering lungs
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Made up of nine separate cartilages:
EPIGLOTTIS
THYROID CARTILAGE
CRICOID CARTILAGE
(2) ARYTENOID CARTILAGES
(4) Smaller cartilages we’re not going to name
EPIGLOTTIS closes when you swallow so nothing will go into the trachea. When you
get hiccoughs, it’s from a sudden movement of air into the lungs, so the epiglottis closes
to prevent more air from going in. It’ unknown why you get hiccoughs. All the
treatments you can try involve interrupting the normal breathing patterns.
GLOTTIS is the opening.
VOCAL CORDS (dense irregular fibrous connective tissue)
Vocal cords are attached to the ARYTENOID CARTILAGES. If these cartilages
move, the vocal cords open. When they go back to normal, the glottis will close.
For air to move through, muscles have to contract. If muscles here are paralyzed, the
airway closes. In surgery, have to intubate. In an emergency, have to do a tracheotomy
above the jugular notch.
The type of sounds you make depend on how far apart the vocal cords are.
Way open = no sound (like when breathing)
Mostly closed = sounds
Men: their thyroid cartilage is larger, so their vocal cords are longer = deeper voice.
LARYNGITIS: inflamed vocal cords (↓ sound production).
Singers can get scar tissue nodules, requires surgery.
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LECTURE 14 (Respiratory System)
TRACHEA (30 mins)
This is a tube that carries air from the larynx to the lungs. (See model)
It’s fairly rigid from about 16 rings of cartilage.
The purpose of the cartilage rings is to keep the trachea open. Otherwise, when you
inhale, the trachea would collapse like when you suck hard on a straw. That’s why your
vacuum cleaner has rings on the hose.
Histology of the trachea
Inner layer: MUCOSA
1. Epithelium (pseudostratisfied epithelium) and goblet cells. Function of goblet
cells is to produce mucous to trap dirt. Cilia move dirt to larynx  swallowed.
2. LAMINA PROPRIA (loose fibrous connective tissue) with lots of elastic fibers
to make the trachea flexible.
Deep to the mucosa: SUBMUCOSA. This is the serous portion to humidify the air.
Superficial to the mucosa: ADVENTITIA LAYER (dense connective tissue with hyaline
cartilage.
The trachea branches into the RIGHT and LEFT BRONCHUS (the primary bronchi).
These branch into the secondary bronchi, which branch into the tertiary bronchi.
The layers become thinner, and the hyaline cartilage no longer has nice rings; just bits.
If you inadvertently inhale something, which lung does it go into? Right lung.
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The tertiary bronchi are microscopic. Beyond them are the bronchioles.
BRONCHIOLES (simple columnar epithelium, no cilia, no mucosa). Surrounding this
is a smooth muscle layer; functions to direct the flow of air to particular portions of the
lungs.
Right now, only a small percentage of lungs are needed, compared to if you are running.
Since there are no cilia, any particle that gets down that far has to be eaten by
macrophages or just stay there. In allergic conditions, bronchioles will constrict,
blocking air flow to the lungs = ASTHMA. This can also be caused by irritants in the
environment, especially by pollution in the city.
Bronchioles branch into TERMINAL BRONCHIOLES (simple cuboidal), which
empty into a sack = ALVEOLUS (simple squamous epithelium) (overhead picture).
This sac is like a balloon surrounded by a capillary bed. Within the alveoli are
macrophages.
Smoking destroys cilia, and smoke of any kind is toxic. Particles in the lungs can’t clear.
Cigarettes contain tar, which is the same kind of tar used to pave roads. When there is a
thin lining of tar on the alveoli, there is no oxygen exchange to the lungs there. Large
chunks of the lung become useless. Damage to the lungs shows up several ways.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)
Number 5 killer in the USA.
It is a combination of two conditions:
1. CHRONIC BRONCHITIS: inflammation of the bronchi, produces mucous, the
openings become smaller = obstructed.
2. EMPHYSEMA: loss of elastic tissue on the bronchioles and alveoli, which
collapse now during exhalation. Alveoli lose their shape and their surface area.
When you see someone at the mall with an oxygen tank, they probably have
emphysema, and need pure oxygen.
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If a person stops smoking after 10 years, damage will repair. Longer than 10 years may
have some residual damage. It takes 7 years for lungs to repair. Smoking right after
exercise is worse because you are breathing more deeply. Pollution in the air can also
cause particles in the lungs, and the ozone can damage the lungs. Living in southern
California is like smoking one pack a day. A mother who smokes during pregnancy will
give birth to a baby with a lower birth weight.
LUNG CANCER (20 mins)
There are many types of lung cancers. About 150,000 die each year from them.
It is the #1 or #2 most deadly form of cancer.
85% of lung cancer is caused from smoking.
The problem is that it starts as a hard nodule deep in the spongy tissue of the lung, where
it has no symptoms until it presses against a structure. By then, it has also metastasized.
Surgery on a smoker won’t work because the lungs are too weak, and they can’t do
without the lung tissue. There are no good screening procedures for lung cancer.
SURFACTANT is a detergent produced within the alveoli, which coats it. It functions
to keep the walls of the alveoli from sticking together when they collapse during
exhalation. If you have two wet pieces of paper and stick them together, they are hard to
pull apart without ripping. Put soapy water between them, and you can pull them apart.
Surfactant is not produced in a fetus until the ninth month, so premature babies don’t
have enough surfactant  RESPIRATORY DISTRESS SYNDROME, which is the #1
cause of death in premature babies. You know how hard it is to blow up a brand new
balloon? Imagine a baby having to do that with every single breath. You get tired. The
treatment is to spray artificial surfactant into the lungs, and put them on a respirator to
push air in. The more distal regions are still collapsed, so there are problems.
Lining the thoracic cavity is PARIETAL PLEURA.
Lining the lungs is the VISCERAL PLEURA.
Both of these are made of 2 layers (simple squamous epi and loose fibrous ct), same as
the pericardium. Between these pleura is a tiny space: PLEURA CAVITY.
The pleura lubricate the lungs so when the lungs move, it is smooth. They also form an
airtight seal to allow the lungs to inflate.
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When the lungs inflate, the thoracic cavity expands for two reasons:
1. The diaphragm pulls down, increases volume
2. The rib cage expands, increases volume.
Model: Pull down on diaphragm, balloons blow up.
If there is a hole in the pleura (injury from broken rib, knife), it’s like opening the
stopper; air flows in through the hole, and the lungs don’t inflate = PNEUMOTHORAX
(air in thorax)  COLLAPSED LUNG.
A more common problem is an infection of the pleura = PLEURISY. With every breath,
the pleura rub together  pain like a broken rib.
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