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Human Physiology 2 > Week Four > Flashcards

Week Four Flashcards

1
Q

arteries are ____________ reserviors

A

pressure

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2
Q

veins are ___________ reservoirs

A

volume/blood

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3
Q

Where does exchange between the blood and the cells take place?

A

in the capillaries

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4
Q

How is blood propelled forward within the systemic system?

A

the elasticity of the arteries propels the blood forward

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5
Q

Which blood vessel holds the highest pressure?

A

the aorta

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6
Q

True or false: we have more veins than arteries

A

true

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7
Q

True or false: arteries hold much more blood than veins

A

false; veins hold much more blood than arteries

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8
Q

What are the three layers or arteries and veins that we should know? name them from deep to superficial

A

tunica intima, tunica media, tunica externa

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9
Q

Describe the tunica intima

A

innermost lining; is one layer of endothelial cells (simple squamous epithelia) + layers of connective and elastic tissue

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10
Q

Describe the tunica media

A

middle layer; consists of smooth muscle + elastic laminae

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11
Q

Describe the tunica externa

A

outer layer of dense irregular collagen out connective tissue

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12
Q

the smooth muscle cells of the tunica media are innervated by the ___________________________

A

sympathetic nervous system

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13
Q

what does contraction of the sympathetic nervous system cause in the tunica media

A

vasoconstriction → decreased vessel diameter

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14
Q

What does relaxation of the sympathetic nervous system cause in the tunica media?

A

vasodilation → increased vessel diameter

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15
Q

Describe the comparison of the structure of arteries and veins

A
  • veins typically have much thinner walls, fewer elastic fibers, less smooth muscle, and larger lumens
  • most arteries have much thicker tunica media (role in controlling blood flow and pressure) and more internal and external elastic laminae (due to higher BP)
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16
Q

Describe the function and structure of elastic arteries

A
  • large arteries with well-delivered elastic laminae
  • conduct blood under high pressure to organs (aorta)
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17
Q

Describe the function and structure of muscular arteries

A
  • thick-walled arteries with a well-developed tunica media
  • control blood flow to organs + regulate blood pressure
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18
Q

Describe the structure and function of arterioles

A
  • thin walls with all three tunics
  • control blood flow to tissues + feed capillary beds, + regulate blood pressure
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19
Q

Describe the structure and functions of venules

A
  • small venules have only a tunica intima; larger venules have have all three tunics
  • drain capillary beds
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20
Q

Describe the structure and function of veins

A
  • thin walled vessels with a large lumen, little smooth muscle, and valves
  • return blood to the heart
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21
Q

Describe capillary exchange

A
  • nutrients, gases, ions, and wastes can cross the capillary wall to travel between the blood in capillary and tissue cells
  • movement occurs via diffusion and osmosis (through gaps and pores), and by transcytosis (via endothelial cell)
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22
Q

Describe continuous capillaries

A
  • endothelial cells joined by tight junctions
  • found in skin, most nervous and connective tissue, and muscle tissue
  • least “leaky” - permit a narrow range of substances to cross the capillary walls
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23
Q

Describe fenestrated capillaries

A
  • contain fenestrations in the endothelial cells
  • found in kidney, endocrine glands, and small intestine
  • moderately leaky - allow large volumes of fluid and larger substances to cross capillary walls
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24
Q

Describe sinusoidal capillaries

A
  • discontinuous sheet of endothelium irregular basal laminate, very large pores
  • liver, lymphoid organs, bone marrow, and spleen
  • leakiest - allow large substances such as cells to cross the capillary walls
25
Q

Describe blood flow through capillary beds

A
  • blood flow through capillary beds is regulated based on tissue needs (e.g. active skeletal muscles during exercise requires have higher metabolic needs, thus more capillary beds open up)
  • regulation due to contraction/relaxation of pre capillary sphincters and diversion through metarterioles
26
Q

How is blood flow in tissues regulated?

A

1) by opening/closing of pre capillary sphincters
2) vasocontriction/vasodilation of arterioles
(goal is to match perfusion to tissue demands)

27
Q

Describe how blood flows down a pressure gradient

A
  • pressure gradient created by force of the heart pump
  • flows from high P → low P
28
Q

What is the main determinant of flow rate (L/min) through the blood vessels?

A

magnitude of the pressure gradient

29
Q

Define blood pressure

A

outward force that blood exerts on the blood of the vessels (units: mmHg)

30
Q

Describe the relationship between resistance, blood viscosity, vessel radius, and vessel length

A

resistance is directly proportional to blood viscosity and vessel length, and is inversely proportional to vessel radius

31
Q

Describe the equation of blood flow, blood pressure gradient, and resistance

A

blood flow = blood pressure gradient/resistance
- the pressure gradient creates the blood flow
- the total resistance is the impedance to blood flow

32
Q

Describe the relationship between current, voltage gradient, resistance

A

current = voltage gradient/resistance
- the voltage creates the current
- the total resistance is the impedance to the current

33
Q

Describe the relationship between velocity of blood flow and cross sectional area

A

the two are inversely proportional
- total cross sectional area increases as arteries branch into many of smaller vessels
- as total cross sectional area increases, the same amount of blood is now filling the equivalent of a much larger container → velocity of flow slows down

34
Q

Define systolic pressure

A

the pressure of the blood against the artery walls during systole

35
Q

Define diastolic pressure

A

the pressure of the blood against the artery walls during diastole

36
Q

What is pulse pressure

A

the difference between systolic and diastolic P
PP = SP - DP

37
Q

How do we calculate mean arterial pressure?

A

MAP = diastolic pressure + 1/3 (systolic pressure - diastolic pressure)

38
Q

When is ‘pulse pressure’ gone

A

by the time blood reaches the arterioles

39
Q

What are the three factors that determine blood pressure

A

peripheral resistance, cardiac output and blood volume

40
Q

Describe the relationship between peripheral resistance and blood pressure

A
  • as peripheral resistance increases, blood pressure also increases
41
Q

Define and describe peripheral resistance

A
  • peripheral resistance is caused by anything that hinders blood flow through the vasculature periphery
  • influenced by blood viscosity, blood vessel length,, blood vessel radius, and obstruction to vessels
42
Q

How does blood viscosity influence peripheral resistance

A
  • the more viscous a liquid, the more its molecules resist being put into motion and staying in motion. Blood has a relatively high viscosity due to number of proteins and cells it contains AKA peripheral resistance and blood viscosity are directly proportional
43
Q

How does blood vessel length influence peripheral resistance

A
  • the longer the blood vessel, the greater the resistance; more pressure is needed to propel blood through a longer vessel than a shorter one. (this is one reason why resistance in pulmonary circuit is so much lower than in systemic circuit)
44
Q

How does blood vessel radius influence peripheral resistance?

A

resistance varies inversely with vessel’s radius; as radius increases (vasodilators) resistance to blood flow decrease, and vice versa

45
Q

How does cardio output influence blood pressure?

A
  • cardiac out put is a product of stroke volume and heart rate; when cardiac output increase, blood pressure increases and vice versa
46
Q

How does blood volume affect blood pressure?

A
  • total blood volume is directly linked to amount of water in the blood; when blood contains more water, blood volume increases; as blood volume increases, blood pressure increases and vice versa
47
Q

Describe blood pressure in the pulmonary circuit

A
  • pressure doesn’t change much - it remains fairly low from pulmonary artery to pulmonary veins
48
Q

Describe pressure in the systemic circuit

A

In the systemic circuit, pressure decreases from arteries → arterioles → capillaries → venules → veins

49
Q

Define mean arteries pressure

A

average pressure in the arterial circuit

50
Q

Describe pressure in the vessels from most pressure to least pressure

A

aorta → elastic arteries → muscular arteries → arterioles → capillaries → venules → veins → vena cavae

51
Q

What are skeletal muscle pumps?

A

the skeletal muscles surrounding the deeper veins of the limbs squeeze blood in the veins to help propel it toward the heart

52
Q

True or false: our veins have valves to ensure one-way flow back to the heart

A

true

53
Q

Which three systems mainly help to regulate blood pressure?

A

nervous, endocrine, and urinary systems

54
Q

Describe short term maintenance of blood pressure

A

short-term maintenance primarily from nervous system → adjustments to peripheral resistance and cardiac output; autonomic nervous system (via epinephrine and norepinephrine)

55
Q

Describe long-term maintenance of blood pressure

A

long term maintenance from kidneys and endocrine system
- BP regulation by increasing or decreasing the amount of body water lost as urine → changes blood volume
- many hormones act on the kidney to modulate fluid retention/loss e.g. ADH

56
Q

What do the specialized mechanoreceptors found in the walls of the aortic arch and common carotid artery do?

A

respond to stretch in artery wall

57
Q

Describe the baroreceptor reflex to increased blood pressure

A

increased blood pressure → increased stretch of the wall → baroreceptors in the carotid sinus detect the increased pressure and fire action potentials at a faster rate to the SNS → the impulses travel to the medulla of the brainstem for integration → autonomic centres in the medulla inhibit sympathetic activity, inducing vasodilation and decreased heart rate, lowering cardiac output → decreased blood pressure

58
Q

Describe the Baroreceptor reflex to decreased blood pressure

A

Decreased blood pressure → decreased stretch of the wall → baroreceptors detect the decreased pressure and lower their rate of firing to the SNS → the impulses travel to the medulla for integration x → medulla increases sympathetic output and decreased parasympathetic output, increasing heart rate and contractility (increased cardiac output) and allowing vasoconstriction (increases peripheral restriction) → blood pressure increases

Human Physiology 2 (9 decks)

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