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Physiology > Chapter 15 > Flashcards

Chapter 15 Flashcards

1
Q

which vessels have the thickest walls?

A

arteries

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2
Q

Which vessels have the thinnest walls?

A

veins

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3
Q

Which vessels have the largest lumens?

A

veins

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4
Q

Which vessels have the most smooth muscle?

A

arteries

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5
Q

Arteries act as ______ __________

A

pressure reservoir

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6
Q

What is the site of variable resistance?

A

arterioles

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7
Q

what are metarterioles?

A

branches of arterioles

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8
Q

What are the smallest vessels?

A

capillaries

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9
Q

what happens in the capillaries?

A

primary site of exchange between blood and interstitial fluid

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10
Q

_________ _________ open and close to direct blood flow to capillaries or venous circulation.

A

precapillary circulation

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11
Q

what do venules do?

A
  • receive blood from capillaries
  • convergent pattern of flow
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12
Q

Veins act as a ______ _________

A

volume reservoir

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13
Q

what are the functions of veins?

A

contain one way valves that prevent backward flow

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14
Q

what is angiogenesis?

A

development of new blood vessels

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15
Q

what is angiogenesis controlled by?

A

cytokines

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16
Q

Explain what creates blood pressure.

A
  • measure of the strength of the pressure wave produced by ventricular contraction
  • systolic pressure - diastolic pressure
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17
Q

Describe how blood pressure is estimated using sphygmomanometry.

A
  • goal is to increase pressure to above systolic pressure
  • cuff is inflated so that it stops arterial blood flow –> no sound can be heard through a stethoscope placed over the brachial artery below the cuff
  • release pressure
  • read gauge –> once the pressure in the cuff is equal to the systolic pressure –> blood is able to get thru
  • hear flow of blood (estimate # on gauge –> systolic pressure)
  • stop hearing blood flow when there is no more compression (estimate # on gauge –> diastolic pressure)
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18
Q

What is the equation used to find MAP?

A

MAP = diastolic pressure + ((1/3) x (pulse pressure)

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19
Q

If flow into arteries exceeds flow out, then arterial blood volume increases and MAP ______

A

increases

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20
Q

Cardiac output is flow out of ______ ______ (into aorta)

A

left ventricle

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21
Q

What is the relationship between blood volume and pressure?

A

direct relationship

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22
Q

Define myogenic autoregulation.

A

vascular smooth muscle regulates its own state of contraction

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23
Q

Explain myogenic autoregulation’s role in altering local blood flow.

A
  • stretched vascular smooth muscle open mechanically gated Ca2+ channels
  • Ca2+ flows into cell
  • leads to contraction
24
Q

List and describe the major paracrine molecules involved in local control of blood flow.

A
  • stretch –> causes vasoconstriction
  • paracrine –> released in response to metabolism + cause vasodilation
  • endothelin –> in response to tissue damage (constricts vessel)
25
Q

Sympathetic innervation releases ____ on most systemic arterioles.

A

NE

26
Q

What does sympathetic innervation do?

A
  • maintains arteriolar tone
  • binds alpha receptors –> vasoconstriction
27
Q

what does the adrenal medulla do?

A
  • releases epinephrine into blood
  • binds alpha receptors w/very low affinity –> vasoconstriction
  • binds beta2 receptors on vascular smooth muscle of heart, liver, and skeletal muscle arterioles –> vasodilation
28
Q

When blood pressure increases due to increased blood volume, what is the fast response?

A

compensation by cardiovascular system –> vasodilation + decreased cardiac output –> decreased blood pressure –> normal bp

29
Q

When blood pressure increases due to increased blood volume, what is the slow response?

A

compensation by kidneys –> excretion of fluid in urine decreases blood volume –> decreased blood pressure –> normal bp

30
Q

Describe the neural control of blood vessel diameter, including significant neurotransmitters + their receptor types.

A

Neural control:
- sympathetic –> alpha receptors –> constricts
- epinephrine
- alpha receptors –> vasoconstriction
- beta receptors –> vasodilation
- norepinephrine
- alpha receptors –> vasoconstriction
- beta receptors –> vasodilation

31
Q

Explain how the body can use local + long distance signaling to direct blood flow to or away from specific organs or tissues.

A
  • blood distribution varies according to metabolic needs –> local
  • arterioles arranged in parallel (circuit) –> how body is able to do long distance –> (doesn’t need to flow thru the whole circuit to get back to the heart)
  • can vasoconstrict a vessel to increase resistance + flow thru other vessels –> flow is taken to lower resistance vessels
32
Q

Describe the control of blood flow to the brain + heart.

A
  • cerebral blood flow stays nearly constant
  • coronary blood flows parallel to the work of the heart
33
Q

Describe in detail the steps of the baroreceptor reflex if the stimulus increases arterial pressure.

A

1) stimulus –> increased bp
2) sensor –> carotid + aortic baroreceptors
3) afferent pathway –> sensory neuron
4) integrating center –> medullary
cardiovascular control center (CVCC)
5) output signal –> parasympathetic
neurons –> more ACh on
muscarinic receptor
6) target –> SA node
7) tissue response –> decreased HR +
decreased cardiac output
8) systemic response –> decreased blood
pressure
9) negative feedback

34
Q

What does the baroreceptor reflex control?

A

blood pressure

35
Q

Where are the baroreceptors located?

A

baroreceptors located in carotid (to brain) arteries + aorta

36
Q

What is the control center in the baroreceptor reflex?

A

CVCC –> cardiovascular control center (CVCC) in the medulla oblongata in brainstem

37
Q

Describe in detail the steps of the baroreceptor reflex if the stimulus decreases arterial pressure.

A

Look on paper drawing

38
Q

Describe the different types of capillaries and where they are found in the body.

A

1) continuous capillaries –> “normal” + found
in most of the body –> do not have holes
- have leaky junctions –> allow water +
small dissolved solutes to pass
- have endothelial cells beneath basement
membrane
- have transcytosis vesicles
2) fenestrated capillaries –> have holes + large
pores
- have epithelial cell junctions
- basement membrane is cut
- have transcytosis vesicles
- found in –> kidneys
3) sinusoids –> modified capillary vessel
- found in –> bone marrow, liver, and spleen

39
Q

Explain why the velocity of blood flow is lowest in the capillaries.

A
  • want slower velocity for exchange sites of oxygenated + deoxygenated blood
  • smaller diameter + largest total cross sectional are
40
Q

Explain the role of diffusion and transcytosis in capillary exchange.

A

transcytosis:
- only water + small dissolved solutes allowed to pass thru leaky/cell junctions
- everything else that doesn’t fit has to be transported via transcytosis
1) brings proteins + macromolecules across endothelium
2) some vesicles may fuse to create temporary channels (theorized)

diffusion:
- exchange between plasma + interstitial fluid occurs by:
- paracellular pathway –> going btw cells
- endothelial transport –> moving across
cell
- small dissolved solutes + gases
- depends on lipid solubility + concentration gradient

41
Q

Explain the forces that influence capillary filtration and absorption.

A

filtration –> hydrostatic pressure encourages plasma to leave capillaries

absorption –> osmotic pressure (capillaries have plasma proteins that draw water inside to themselves)

42
Q

What type of tissue are the capillary walls made up of?

A

single layer of flattened endothelial cells

43
Q

What is capillary density related to?

A

metabolic activity of cells

44
Q

Describe velocity of flow.

A
  • the distance a fixed volume of blood travels in a given period of time

v = Q/A

Q = flow rate
A = cross-sectional area of the tube

45
Q

Describe bulk flow.

A

a mass movement as a result of hydrostatic or osmotic pressure gradients

46
Q

Describe filtration.

A

fluid movement out of capillaries

47
Q

Describe absorption.

A

fluid movement into capillaries

48
Q

Hydrostatic pressure ________ over the length of capillary due to friction + filtration.

A

decreases

49
Q

Define hydrostatic pressure.

A

the pressure that fluid exerts on the walls of container –> plasma on capillary walls

50
Q

Define osmotic pressure.

A

the pressure that causes osmosis due to solutes/proteins in fluid

51
Q

_____ ______ determines direction of bulk flow.

A

net pressure

52
Q

What is the equation for net pressure for systemic capillaries?

A

PNET = PH - π

53
Q

If PH > π will it be absorption of filtration and at what location?

A

net filtration at arterial end

54
Q

If PH < π will it be absorption of filtration and at what location?

A

net absorption at venous end

55
Q

What are the functions of the lymphatic system?

A

1) returns fluid + proteins to circulatory system
2) absorbs fat from GI tract + transfers it to circulatory system
3) filters pathogens
4) allows for one way movement of interstitial fluid into the circulatory system

Physiology (18 decks)

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