Phys 3 Exam 2

What are the functions of the circulatory system?

1. carry blood

2. exchange nutrients, waste products and gases

3. transportation of hormones

4. regulate blood pressure

5. direct blood flow

Which artery carries de oxygenated blood away from the heart?

pulmonary arteries

Which structure connects smallest arteries to smallest veins?

Capillaries

What vein carries oxygenated blood to the heart?

pulmonary veins

What two circuits does arteries and veins transport blood through?

1. Systemic circuit

2. Pulmonary circuit

What type of blood is transported back to the heart after the systemic circuit?

deoxygenated blood

Where is blood carried to after the systemic circuit?

lungs

What is the purpose of arteries having thicker walls?

they are closer to the heart and receive blood that is surging at a high pressure

Why do arteries have smaller lumens?

to help maintain pressure of blood moving through system

What type of appearance do arteries have?

round appearance

What type of appearance do veins have?

collapsed appearance when not full

What is layers of the vessel walls? (inside to outside)

1. Tunica interna

2. Tunica media

3. Tunica externa

What is the tunica interna made up of?

endothelium

What are the functions of tunica interna?

1. selectively permeable

2. secretes chemicals→vasodilation/vasoconstriction

3. repels blood cells and platelets (repel clots)

4. damage to endothelial lining is primary cause of clot formation (collagen fibers)

What is the difference between the arteries and veins of the tunica intima?

Arteries→wavy due to internal elastic membrane

Veins→smooth due to lack of internal elastic membrane

What is the thickest layer in arteries?

tunica media

What makes up the tunica media?

consists of smooth muscle, collagen, and elastic tissue

What part of tunica media strengthens vessel and prevents blood pressure from rupturing them?

smooth muscle

What is vasomotion?

ability of a blood vessel to change its lumen diameter

How is diameter of blood vessel changed?

through vasoconstriction and vasodilation

What are nervi vasorum?

small nerves that intervate smooth muscle and cause vasoconstriction and vasodilation

Where is the external elastic membrane layer present in a larger artery?

tunica media

What layer consists of loose connective tissue?

tunica externa

What layer acts as an anchor for vessels and provides passage to nervi vasorum?

tunica externa

What are vasa vasorum?

small vessels that supply blood to outer part of larger vessels

What layer has the thickest layer in veins?

tunica externa

What is known as resistance vessels because of their strong, resilient tissue structure?

Arteries

What is the biggest arteries?

conducting arteries

Aorta is considered a ___ artery

conducting

What type of artery has the most elastic fibers?

conducting arteries

Conducting arteries have a ___ resistance and ___ pressure

low resistance

high pressure

What is the function of a distributing artery?

distributes blood to specific organs

What type of artery consists of is 75% smooth muscle?

Distributing arteries

What are resistance arteries known as?

arterioles→ smallest arteries

Due to resistance arteries size, blood flow will __ and there will be a __ in BP

slow

drop

What are the three layers of arterioles?

1. thin endothelial lining of tunica intima for exchange

2. tunica media is thick

3. tunica externa is very thin

What is a weak point in artery or heart wall?

Aneurysm

Explain how an aneurysm occurs

weak point in artery/heart wall→thin walled bulging sac that could rupture→due to degeneration of tunica media→blood accumulation between tunics and seperates them

What causes the weak point in the artery?

degeneration of tunica media

What are the most common sites for aneurysms?

1. Abdominal aorta

2. Renal arteries

3. Arterial circle at base of brain

If an aneurysm ruptures, it can cause a ___

hemorrhage

What is the most common causes of aneurysms?

1. Atherosclerosis

2. High blood pressure (hypertension)

What is the function of arterial sense organs?

Transmits information to brainstem to regulate blood pressure, vessel diameter, and respiration

What are two arterial sense organs?

1. Baroreceptors

2. Chemoreceptors

Where are baroreceptors located?

1. Aortic arch→vagus nerve

2. Carotid sinuses→glossopharyngeal nerve

What are the functions of baroreceptors?

1. monitor blood pressure

2. allow for baroreflex

What are the locations of chemoreceptors?

1. carotid bodies→glossopharyngeal nerve to brainstem respiratory centers

2. aortic bodies→vagus nerve

What is the function of carotid bodies?

measures blood pH, Co2 levels, and O2 levels

adjust respriatory rate based on levels

What is a capillary?

site where gases, nutrients, wastes, and hormones pass between the blood and tissue fluid

What is another name for capillaries?

exchange vessels

How is capillary flow described?

microcirculation→circulation of blood through the smallest vessels, arterioles, capillaries, venules

Microcirculation causes blood flow velocity to be __

slow

What are capillaries composed of?

1. endothelium (tunica intima)

2. basal lamina (basement membrane)

Where are capillaries scarce?

1. Tendons

2. ligaments

3. epithelia

4. cornea

5. lens of eye

What are the three types of capillaries?

1. Continuous capillaries

2. Fenestrated capillaries

3. Sinusoids

T/F For capillaries to function, walls must be leaky

true

Where do continuous capillaries occur?

vascularized tissues→ (skin and muscles)

Continuous capillaries have __ ___ in order to allow a continuous tube with ___

tight junctions

intercellular clefts

What passes through continuous capillaries?

glucose, water, hormones

Where are fenestrated capillaries located?

kidneys, small intestine

What is the function of fenestrated capillaries?

rapid absorption and filtration

What is the structure of fenestrated capillaries?

riddled with holes (filtration pores)→only small molecules can pass through

Where are sinusoid (discontinuous) capillaries located?

liver, bone marrow, spleen, adrenal medulla

What is the structure of a sinusoid?

irregular blood filled spaces with large fenstrations

What is passed through sinusoids?

proteins (albumin), clotting factors, and new blood cells to enter in circulation

What is a capillary bed?

networks of 10-100 capillaries

T/F capillary beds are supplied by multiple arterioles

false- single arteriole

Where do capillaries transition at the distal end?

venules or drain into thoroughfare channel

T/F at any given time, ¾ of body’s capillaries are shut down

true

What controls flow of blood within capillary bed?

precapillary sphincters

What is a metarteriole?

has structural characteristics of both an arteriole and a capillary

What is unique about metarterioles?

tunica media is not continuous but forms rings of smooth muscle (sphincters) before each capillary

precapillary sphincter regulates what?

flow of blood from metarteriole to capillaries

T/F Normallly, precapillary sphincters are open

false-closed

What is a vascular shunt?

when precapillary sphincters in capillary bed are closed, so blood goes through from metarteriole to thoroughfare channel into venous circulation

What is an arteriovenous anastomosis?

if blood is not needed at capillary bed, blood can go to an additional vessel into a venous circulation

What are some features of veins?

1. thinner walls

2. less muscular and elastic tissue→expand easily

3. decreased blood pressure

What are postcapillary venules?

smallest veins

more porous than capillaries

thin tunica media→few muscles and elastic fibers

What are muscular venules?

one or two layers of smooth muscle

thin tunica externa

What are medium veins?

tunica interna forms venous valves

Skeletal muscle pump propels venous blood back towards heart

What are large veins?

smooth muscle in each layer

tunica externa is the thickest layer

Vena cava, pulmonary veins, internal jugular vein, and renal veins are examles of what?

large veins

What are venous sinuses?

NO SMOOTH MUSCLE

veins with very thin walls

large lumen

can’t perform vasomotion

What are varicose veins?

blood pools in lower legs of people who stand for long periods stretching the veins→cusps of the valves pull apart in enlarged superficial veins weakens vessels

Blood backflows

What are risk factors of varicose veins?

1. age

2. hereditary

3. obesity

4. prolonged sitting or standing

5. venous insufficiency

6. pregnancy

What are hemorrhoids?

varicose veins of the anal canal

What are some treatments for varicose veins?

1. lifestyle changes

2. sclerotherapy→injection into collapsed veins

3. laser ablation→laser therapy to close the veins

4. Surgery

How to prevent varicose veins?

1. maintain healthy weight

2. exercise regularly

3. avoid prolonged sitting or standing

4. wear compression stockings

What is the simplest and most common route?

blood passes through only 1 network of capillaries from time it leaves heart until the time it returns

What is the portal system?

blood flows through 2 consecutive capillary networks before returning to heart

What are examples of portal systems? (places that need more absorption and filtration)

1. between hypothalamus and anterior pituitary

2. in the kidneys

3. between intestines to liver

What is the most common type of anastomosis?

venous anastomosis

What is blood pressure?

force that blood exerts against a vessel wall

Where is BP most commonly measured at?

brachial artery of arm

T/F BP is systolic pressure over diastolic pressure

true

What is pulse pressure?

difference between systolic and diastolic pressure

over 60mmHg = greater risk of CVD

What is mean arterial pressure?

mean pressure measured by taking diastolic pressure + 1/3 pulse pressure

What is typical range for MAP?

70-110mmHg

Blood flow in arteries is ___

pulsatile

Blood flow in capillaries and veins is at __ __

steady speed