Anatomy Midterm #2

What is the major difference between veins and arteries?

Arteries have a thick tunica media
Veins have a thin tunica media

What is a pulse?

the expanding and contracting of arteries due to changes in blood pressure

What is the tunica intima

innermost layer of a blood vessel

What 2 parts make up the tunica intima?

endothelium and subendothelial later

what is the endothelium made of?

simple squamous epithelium

What is the subendothelial layer made of?

loose connective tissue (basement membrane)

What is the purpose of endothelium?

prevent clot formation

What is the purpose of subendothelial layer?

provides structure

What is the internal/external elastic lamina?

springy structure that allows the artery to regain its original shape/size

What makes up the tunica media?

smooth muscle

What does the tunica media do?

vasodialation and vasoconstriction (selectively altering blood flow to certain organs dependent on need)

What is the tunica externa made of?

loose connective tissue, contains small blood vessels and nerves for muscle contractions

when is there an increase in pressure in the arteries?

systole

From deep to superficial, name all the layers in an artery.

Tunica intima (endothelium & subendothelial layer), internal elastic lamina, tunica media, external elastic lamina, tunica externa

List all the blood vessels from highest to lowest arterial pressure.

aorta, arteries, arterioles, capillaries, venules, veins, vena cava

What is the aorta and what is its function?

largest artery in the body; pumps blood from the hear to the entire body

What makes the aorta good at its job?

it is very good at stretching and therefore can resist large changes in pressure

What is an aortic dissection?

damage to the tunica intima that causes weak scar tissue, blood works its wat into the space between the tunica intima and tunica media, compressing the true lumen and reducing the heart's ability to pump blood

What puts people at risk for an aortic dissection?

a history of high blood pressure or prior infections

does an aortic dissection increase or decrease arterial pressure?

increase

What is so dangerous about an aortic dissection?

it can turn into an aortic aneurysm and rupture, causing near instantaneous death

How is an aortic dissection treated?

stent graft (open heart surgery)

What are muscular arteries?

mid-sized arteries that control blood flow to organs, has a thick tunica media that can control blood flow via vasoconstriction and vasodilation; high proportion of smooth muscle

What is vasodilation?

opening of the tunica media to allow for more blood flow

What is vasoconstriction?

narrowing of blood vessels to cut of blood flow

What are arterioles?

small arteries that lead to capillary beds; also control flow via vasoconstriction and vasodilation (more finite)

What is the purpose of capillaries?

To exchange all materials (nutrients and wastes) by diffusion. point of delivery (dropping off and picking up)

Where do molecules pass through in capillaries?

intercellular cleft

How large are capillaries?

about the diameter of one red blood cell

What allows capillaries to keep their shape?

basement membrane

What type of tissue makes up capillaries?

simple squamous epithelium

What is an intercellular cleft?

space between each epithelial cell that allows for leakiness

Why are capillaries one cell thick?

to increase the rate of diffusion by decreasing the distance over which it occurs, full red blood cell exposure

what does it mean when we say capillaries are "selectively leaky?"

certain molecules/substances can diffuse out of the capillaries while others can't

What is the only substance that leaks out of capillaries?

plasma

what happens to your capillaries when there is inflammation?

increase in fluid in the tissues, clefts become more open (aka more leaky) which allows the diffusion of white blood cells and other infection fighting agents into the tissue.

What are the components of blood?

plasma, red blood cells, white blood cells, platelets

T/F red blood cells leak through capillaries

F

What is the term that describes the build-up of fluid in the lung?

pulmonary edema

Why are lung capillaries more prone to leakage during inflammation?

they are close to the heart and therefore are more susceptible due to poor heart function

describe the mechanisms of a pulmonary edema

increase arterial pressure = increase capillary leakiness, capillaries leak into the alveolus causing a fluid build-up.

how do you treat a pulmonary edema?

diuretics

what is a diuretic?

A substance that promotes the production of urine which lowers arterial pressure and capillary leaking

Why do veins have valves in their tunica intima?

to prevent blood from going backwards in the veins (resist gravity)

Why do veins not have elastic lamina?

there is no arterial pressure to resist

From deep to superficial, name all the layers in a vein.

Tunica intima (with valves, endothelium, & subendothelial layer), tunica media, tunica externa

What condition is caused by the decomposition of epithelial tissue in veins (especially in the legs)?

varicose veins

What are varicose veins?

big, twisty veins near the skin's surface that are caused by weakened valves, blood is moving backward causing congestion in the vein leading to abnormal stretching

T/F Although varicose veins have bad drainage, they still work, just not as effective

T

How are varicose veins removed cosmetically?

killing the vein by burning it

What are veins?

large vessels carrying large volumes of low pressure blood back to the heart, run close to skeletal muscle to assist with blood flow back to the heart

What are venules?

small vessels that exit capillary beds and merge to form veins (fragile, easily damaged and blood flow restricted)

what structure in the body protects the lungs?

ribs

how many lobes does the right lung have?

3 lobes

how many lobes does the left lung have?

2 lobes

What is the outermost surrounding layer of the lung?

parietal pleura

what is the innermost surrounding layer of the lung?

visceral pleura

What is the space between the two surrounding layers of the lung?

pleural cavity

what is the purpose of the pleural cavity in the lungs?

to maintain the shape of the lungs and to provide protection

Describe the gas exchange occuring in the alveoli

the alveoli put in O2 and take out CO2

Why are alveoli in sacs?

they cluster to conserve space

What is the purpose of type II alveolar cells?

secrete surfactant

What is the purpose of type I alveolar cells?

gas exchange (makes up the wall)

What type of cell makes up type I cells

simple squamous epithelium

What is a macrophage?

giant phagocytic cells (WBC)

what is the purpose of alveolar pores?

equalize pressure between alveoli; connecting individual alveoli

describe the mechanisms by which gas exchange occurs (be specific)

-capillaries connect each alveolus
-alternating cell thickness (alveolar cell, capillary cell, alveolar cell, etc.)
-simple squamous epithelium allows for passive diffusion of dissolved gaseous O2 and CO2 between alveolus and RBCs

what is surfactant?

A detergent-like complex that reduces surface tension and helps keep the alveoli from collapsing
-allows lungs to expand

why is surface tension in the alveoli an issue?

when the alveoli try and expand when breathing in, surface tension would stop the small alveoli from expanding, causing many issues in gas exchange including decreasing efficiency and potentially causing a collapse of the airways

what does ARDS stand for?

acute respiratory distress syndrome

how is pneumonia/ ARDS contracted?

-breathing in bad stuff in the air, which can cause an infection

what are cytokines?

chemical messengers that trigger an inflammatory response

How do normal, healthy lungs fight infections?

once inflammation is perceived, capillaries become leaky which promotes the leaking of cellular fluid (WBCs, proteins, and other noncellular substances) that can fight infections

what is pneumonia?

inflammation of the lungs where portions of the alveoli become "under water", usually spreads slowly over a long period of time

why do alveoli get flooded?

mechanisms to fight infection found in the lungs

what is ARDS?

when flooding of the alveoli happens everywhere at a fast rate, the majority of the lungs become underwater over a shorter period of time, triggering a major immune response and an influx of WBCs into the fluid making it harder for the alveoli to expand and stay open.

what is the mortality rate of ARDS?

40-50%

T/F During ARDS the capillaries become so leaky that RBCs are able tp diffuse through into the alveoli

T

What is the mechanism of the Covid vaccine?

it promotes immunity to the spike protein of the Covid-19 virus

What are the primary and secondary killers of contracting Covid-19?

primary: lung issues such as severe ARDS
secondary: coagulation disorders such as heart attacks and stroke

What area of the body does Covid-19 affect the greatest and why?

lungs- point of infection (breathing in the virus)

What blood vessel does Covid-19 close?

capillaries (especially in lungs)

How do viruses reproduce?

Viruses can reproduce only by infecting living cells

How do viruses attach to living cells?

by binding to the ACE2 receptor

Why does an O2 gas mask not work for people with ARDS?

the alveoli are so flooded that they can't even absorb any O2 even when there is an influx

What are the treatments for ARDS?

RotoProne bed or mechanical ventilator

how does the RotoProne bed work?

it constantly flips the patient over to evenly distribute surfactant to portions of the lungs that are not as affected with the illness

how does a mechanical ventilator work?

positive pressure builds in the ventilator circuit and gas is pushed into the lungs, work is done by the machine. forcefully pop open alveolus which can cause a lot of internal trauma and may never heal correctly

What is the standard pressure inside the lungs?

760 mmHg

what is the anatomical term for "breathing in?"

inspiration

what is the anatomical term for "breathing out?"

expiration

How does the pressure inside the lungs change when breathing? (e.g. increasing or decreasing)

-inspiration: intrapulmonic pressure decreases which forces gas molecules from the environment to rush inside the lungs
-expiration: intrapulmonic pressure increases which forces gasses to exit the lungs via the nose and mouth

How does the diaphragm assist breathing?

The diaphragm contracts and flattens, raises the rib cage, and increasing the volume of the lungs. This creates a partial vacuum and the air rushes inside as there is more space inside the lungs than in the atmosphere. The diaphragm then relaxes increasing the air pressure inside the chest cavity and forcing the air out of the lungs

How does the plural cavity prevent alveolar collapse?

it is always a lower pressure than the inside of the lung cavity which allows each alveoli to stay expanded

what muscles are used during quiet expiration?

none (only diaphragm)

T/F Breathing is manually regulated

F - Breathing can be both manual and autonomic

What is a collapsed lung?

When one or both lungs is smaller than it should be due to an increase in pressure in the pleural cavity

How is a collapsed lung formed?

leaky capillaries in the pleural cavity cause collapse of the alveoli

What is the term that describes when air is inside the pleural cavity (usually from a gunshot wound or stab wound)?

pneumothorax

How is pneumothorax treated?

chest tube (video we saw in class was an emergent chest tube)