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Physiology III - Freedman > Unit 2: Circulation Pt2 > Flashcards

Unit 2: Circulation Pt2 Flashcards

1
Q

T/F. The Vasoactive role of endothelium tends to be more vasoconstriction.

A

False– it tends to be more dilation in natures–> unless it is damaged, then vasoconstrictive

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2
Q

What does endothelium release that inhibits platelet aggregation and relaxes vascular smooth muscle (vasodilation)?

A

Prostacyclin (PGI2)

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3
Q

What three things does the endothelium release that will play its vasoactive role on the vessels?

A

Release:

  1. Prostacyclin (PGI2)
  2. Nitric Oxide (NO)–> when healthy
  3. Endothelin –> when damaged
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4
Q

What does endothelium release when it is healthy that is a vasodilator? What stimulates the release?

A

Nitric oxide
Release Stimulated by:
- shear stress ass. with increase flow
- ACh binding to endothelium

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5
Q

What does endothelium release when it is damaged that causes vasoconstriction and may be contribute to vasoconstriction when endothelium is damaged by hypertension?

A

Endothelin

- constricts vascular smooth muscle

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6
Q

What is the functional unit of circulation?

A

capillaries

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7
Q

Where does bulk of exchange take place in circulation system?

A

capillaries

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8
Q

What is intermittent constriction of metarterioles and precapillary sphincters?

A

vasomotion

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9
Q

What are three mechanisms of capillary exchange?

A
  1. Passive Diffusion
  2. Ultrafiltration
  3. Vesicular Transport
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10
Q

What is the equation for oxygen uptake/utilization ?

A

= the product of flow (F) x arterial-venous oxygen difference

O2 = (F) (A-V O2 diff)

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11
Q

What type of flow is associated with increased oxygen uptake/utilization?

A

Functional or Nutritive flow

end of page 7

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12
Q

What type of flow is associated with shunting of blood through a capillary bed?*

A

Non nutritive flow

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13
Q

What type of capillary exchange involves permeability and concentration gradient?

A

Passive diffusion

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14
Q

What type of capillary exchange involves larger MW non lipid soluble substance?

A

vesicular transport

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15
Q

What type of capillary exchange involves bulk flow through a filter (capillary wall) and Starling Forces (Hydrostate P and Colloid Osmotic P)?

A

Ultrafiltration

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16
Q

What does Hydrostatic Pressure gradient favor?

ass. Ultrafiltration

A 
filtration 
(high to low)
Ex:
- capillary HP averages 17 mmHg
- Interstitial HP avers -3 mmHg
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17
Q

What does Colloid Osmotic Pressure favor? (ass. Ultrafiltration)

A

reabsorption
(low to high)
- Capillary COP averages 28 mmHg
- Interstitial COP average 9 mmHg

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18
Q

What does the Net Filtration Pressure = ?

A

= (Capillary Hydrostatic Pressure - Interstitial HP) - (Capillary Colloid Osmotic Pressure - Interstitial COP)

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19
Q

What is the most abundant plasma proteins?

A

Albumin (75%)

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20
Q

What is the colloid osmotic pressure a function of?

A 
function of the protein concentration 
- like plasma proteins
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21
Q

What is the calculated Colloid Effect? What is the Actual Colloid Effect? What is the discrepancy b/w the two due to?

A 
Calculated = 19 mmHg
Actual = 28 mmHg

Discrepancy due to Donnan Effect

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22
Q

What is the Donnan Effect?

A

is increases the colloid osmotic effect; large MW plasma proteins carries neg. charges which attract pos. ions –> therefore increasing the osmotic effect by about 50%

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23
Q

T/F. Proteins that can and can’t cross capillary walls will exert osmotic pressure.

A

False– ONLY protein that CANNOT cross capillary wall can exert osmotic pressure

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24
Q

What effect can the capillary wall have on Colloid Osmotic pressure?

A

how tight/loose they are

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25
Q

What areas have capillary walls with tight junctions?

What areas have capillary walls that are discontinuous?

A

tight junctions–> BBB

discontinuous–> liver capillaries

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26
Q

Where is the body do capillaries have filtration slits (fenestrations)?

A

Glomerular Capillaries in kidney

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27
Q

What expresses how readily protein can cross the capillary wall?

A 
Reflection Coefficient
(ranges from 0-1)
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28
Q

What does it mean when the Reflection Coefficient = 0? What if it = 1? Where is body would be ass. with these number?

A

If = 0 –> all colloid proteins freely cross wall, none are reflected, and therefore NO colloid effect –> LIVER

If = 1 –> all colloid proteins are reflected, none cross capillary wall, therefore FULL colloid effect –> BRAIN

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29
Q

What drains excess fluid from interstitial space?

A

Lymph capillaries

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30
Q

Where are no true lymphatics found?

A
  • superficial portions of skin
  • CNS?–new finding ass.
  • endomysium of muscle
  • bones
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31
Q

What drains the lower body and left side of head, left arm, and part of chest(3/4)?

A

Thoracic duct

32
Q

What does the right lymph duct drain?

A

right side of head, neck, right arm, and part of chest (1/4)

33
Q

What is the discussion of the CNS having modified lymphatic function?

How are plasma filtrate and escaped substances in perivascular spaces returned to vascular system in CSF?

A

true lymphatic vessels just discovered in CNS near Dural Venous sinuses

via arachnoid villi which empties into Dural venous sinuses

34
Q

Where is 2/3 of all lymph from?

A

liver and intestines

35
Q

What will increase lymph formation?

A

any factor that increases filtration or any factor that decrease reabsoprtion

36
Q

What is the total lymph flow per hour? per day?

A

120 ml/hr

2.9 L/day

37
Q

What is the rate of lymph formation/flow in the Thoracic duct? Right Lymph duct?

A

Thoracic Duct = 11 ml/hr

Right Lymph Duct = 20 ml/hr

(therefore 120 ml/hr total)

38
Q

T/F. Everyday the volume of lymph filtered is roughly equal to our entire plasma volume.

A

True

39
Q

How is arterial blood pressure created?

A

by the interaction of blood with vascular wall

Arterial BP = vol of blood interacting with the wall

40
Q

What does Arterial BP =?

A

CO x TPR (Total peripheral resistance)

41
Q

Where is greater than 1/2 of TPR (total peripheral resistance) occur at?

A

at level of systemic arterioles

42
Q

T/F. A change in pressure follows a change in volume. *

A

True

43
Q

During systole the left ventricular output (SV) is ____ than peripheral runoff. What does this cause?

A

greater

therefore total blood volume rises and causes arterial BP to increase to a peak (=systolic BP)

44
Q

T/F. During systole the veins are distended.

A

False– the arteries are distended during this time

45
Q

When you see systole, think ________. When you see Diastole, think ______.

A

Systole –> stretch

Diastole –> recoil

46
Q

What is occurring during diastolic BP?

A

total blood volume in arterial tree is decreasing, which causes arterial BP to fall to a minimum value

47
Q

What serves to maintain perfusion to the tissue beds when the left ventricle is filling?

A

the arteries are now recoiling

diastole BP

48
Q

What is the stretch (systole) and recoil (diastole) of the arterial tree that normally occurs during the cardiac cycle called?

A

Hydraulic Filtering

49
Q

What phenomenon save the heart work?*

A

Hydraulic Filtering (through stretch and recoil)

– creates intermittent output by the heart to a stead delivery at the tissue beds

50
Q

Describe what happens with age and Hydraulic Filtering.

A

increase in age causes a decrease in distensibility of the arterial tree–> therefore hydraulic filtering is reduced–> and work load on the heart is increased

51
Q

What is the maximum pressure in the systemic arteries?

A

systolic blood pressure

52
Q

When does blood pressure peak?

A

as blood is ejected from left ventricle into aorta (systolic BP)

53
Q

What occurs during systole that causes arterial pressure to increase?

A

inflow volume from LV typically occurs at a faster rate than peripheral runoff out the arterial tree

54
Q

What is the minimum pressure in the systemic arteries called?

A

Diastolic Blood pressure

55
Q

How low the systemic artery BP falls is dependent on what 2 factors?*

A
  1. Cycle Length–> inversely proportional to DBP

2. Total Peripheral Resistance (TPR) –> proportional to DBP

56
Q

What affect will an increase in cycle length have on DBP?*

A

decreases DBP

57
Q

What affect with an increase in TPR (total peripheral resistance) have on DBP?*

A

will increase DBP

58
Q

Will DBP change much during exercise? why or why not?

A

during exercise DBP may not change much due to:

- decrease in cycle length being offset by decrease in total peripheral resistance (TPR)

59
Q

What is the Mean Arterial Blood Pressure?

A

= 1/3 Pulse Pressure + DBP
(approximation)

(it is NOT the arithmetical mean b/w systole and diastole)

60
Q

Example: What is the Mean Arterial Blood Pressure if BP = 120/80

A

120(systole)-80(diastole) = 40(pulse pressure)
1/3 of 40 = ~13
80(diastole)+13 = 93
MAP = 93

61
Q

What do most post-ganglionic SNS terminal release? What is the predominant receptor type?

A

NE; alpha receptor

62
Q

SNS stimulation causes widespread vasoconstriction causing a decrease in blood flow, EXCEPT in what three places?

A
  1. Brain (arterioles weakly innervated by SNS)
  2. Lungs (arterioles weakly innervated by SNS)
  3. Heart (overrides SNS vasoconstriction by local vasodilators, like adenosine)
63
Q

As the arterial pressure falls, what is the critical pressure in which flow ceases due to closure of the arterioles called?

A

Critical Closing Pressure

64
Q

What critical luminal pressure is required to keep arterioles from closing completely?

A

critical closing pressure

65
Q

What is proportional to Critical Closing Pressure?

A

vascular tone

Ex: SNS stimulation of arterioles increases tone and therefore increases CCP

66
Q

What do we call the equilibrium pressure where arterial BP = venous BP?

A

Mean Circulatory Filling Pressure

67
Q

How could Mean Circulatory Filling Pressure occur?

A

if cardiac output is stopped, arterial pressure falls and venous pressure will rise

MCFP –> arterial BP = venous BP

NOT GOOD

68
Q

How do we prevent Mean Circulatory Filling Pressure?

A

by closure of arterioles (critical closing pressure)

69
Q

What occurs if Mean Circulatory Filling Pressure = Central Venous Pressure?

A

venous return goes to 0 –> which = DEATH

70
Q

At a give Mean Circulatory Filling Pressure, as Central Venous Pressure increases, what happens to venous return?

A

venous return decreases

71
Q

What can we gather from a Vascular Function Curve?

A

Venous return on Y axis and Central Venous Pressure of X axis

–where the Vascular Function curve intersects with x-axis–> will be where Venous return = Central venous pressure –> and is called the Mean Circulatory Filling Pressure

72
Q

As Central Venous Pressure increases, what happens to cardiac output? What is this due to?

A

CO will increase; due to intrinsic and extrinsic effects

73
Q

What is the Cardiac Function Curve?

A

CO on Y-axis and Central Venous Return on X-axis

–as CVP increases so does CO

74
Q

What is the pressure in the central veins (superior and inferior vena cava) at the entry into the right atrium called?

A

Central Venous Pressure

75
Q

T/F. Central Venous Pressure = right atrial pressure

A

True

76
Q

T/F. Walking and laying down = more similar physiologically in a cardiovascular sense.

A

True (b/c when just standing, blood pools, but when talking you pump it back to heart and it is more even throughout body, just like how it is when you are lying down)

Physiology III - Freedman (18 decks)

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