Blood pressure Flashcards

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1
Q

What is blood pressure

A

force against blood vessels walls by blood in vessels in mmhg (maintains blood flow in tissues)

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2
Q

When is systolic BP measured

A

during ventricular systole (peak pressure in arteries as ejected from heart)

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3
Q

when is diastolic BP measured

A

during ventricular diastole (low pressure)

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4
Q

what is the artery commonly used to measure BP

A

brachial

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5
Q

what tool is used for BP

A

sphygmomanometer

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6
Q

what is pulse pressure

A

difference between systolic & diastolic

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7
Q

what is mean arterial pressure

A

average pressure

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8
Q

What are the factors affecting BP

A

1) Peripheral resistance
2) Cardiac output
3) Blood volume

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9
Q

What are the sources of peripheral resistance

A
  • Diameter
  • Length
  • Blood viscosity
  • Turbulence
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10
Q

What is peripheral resistance?

A

resistance to blood flow

hi PR = heart has to work harder

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11
Q

What is largest contributor to PR?

A

BV diameter

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12
Q

What does a decreased diameter do?

A

Increases BP & PR

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13
Q

What are the most resistance vessels?

A

Arterioles

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14
Q

explain how length is a source of PR

A

increased length = increased SA encountered = Increased friction = increase PR = increased BP

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15
Q

What is blood viscosity

A

thickness

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16
Q

what happens with increased viscosity

A

increased viscosity Increases PR & BP

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17
Q

What is blood turbulence

A

swirling of blood it increases PR

-could be an irregular surface or a slugger change in diameter

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18
Q

how does cardiac output affect BP?

A

veins are blood reservoirs that hold 65% of the blood at rest,
if you increase venous return you’ll increase BP

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19
Q

how does blood volume increase BP

A

increased volume = increased BP

high na intake = increased BP (b/c volume will rise)

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20
Q

What are the 3 forms of regulation of BP and Blood flow

A

1) Neural control - sympathetic
2) Local/ intrinsic control
3) Hormonal control
- ADH -ANP -RAAS

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21
Q

What is meant by vasomotor control (part of neural control)

A

The medulla oblongata sends signals to the vasomotor centre which signals the sympathetic division to release NE which will cause the contraction of smooth muscle in BV.
If you stimulate this response then it will cause vasoconstriction.
if you inhibit this it will cause vasodilation.

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22
Q

what is sympathetic tone

A

it facilitates venous return bu increasing BP in veins and maintains BP in arteries / arterioles

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23
Q

What is the main receptor that detects BP

A

Baroreceptor (detects stretch)

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24
Q

What is the baroreceptor initiated reflex

A

vasoconstriction to maintain BP to ensure blood delivery

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25
Q

what is the carotid sinus reflex

A

baroreceptors in the internal carotid A protect the blood supply to the brain

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26
Q

What is the aortic reflex

A

baroreceptors in the aortic arch protect blood supple to heart and body

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27
Q

explain local/ intrinsic control of BP

A

vasodilation is triggered by changes in the tissue environment
*THE NERVOUS SYSTEM IS NOT INVOLVED.

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28
Q

What are some causes of local control of BP

A
  • increased CO2, decreased O2
  • Decreased ph
  • increased temp
  • histmaine release
  • nitric oxide
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29
Q

Where is nitric oxide released from?

A

Endothelial cells

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30
Q

What does nitric oxide do?

A

relaxes smooth muscle in tunica media by triggering ca2+ uptake into SR

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31
Q

What are the 3 main hormones/systems that control BP

A

ADH (Antidiuretic/ vasopressin)
ANP (Atrial natriuretic peptide)
RAAS (Renin angiotensin aldosterone system)

32
Q

where is ADH made

A

Hypothalamus

33
Q

where is ADH released from

A

posterior pituitary

34
Q

Why is ADH released?

A

In response to dehydration

35
Q

Explain the mechanism of ADH

A
  • baroreceptors detect low blood volume
  • osmoreceptors detect increased solute concentration
  • ADH is released and causes: Vasoconstriction & increased H2O reabsorption by kidneys
  • This increases blood volume & thus increases blood pressure
36
Q

Where is ANP (Atrial natriuretic peptide) made?

A

Produced in the heart (R Atrium)

37
Q

Why is ANP released?

A

In response to increased stretch of the right atria (filling too quick)

38
Q

What is the effect of ANP

A

decreases blood volume & blood pressure

39
Q

What is the mechanism that ANP works?

A
  • It is released in response to the R atria filling too quick
  • it causes the kidneys to decrease blood volume by instead creating more urine & it decreased sympathetic release of NE (causing vasodilation).
  • It also decreased the release of ADH & aldosterone
40
Q

What activated RAAS?

A

Activated by low blood pressure in the kidneys

41
Q

What is the other all effect of RAAS?

A
  • Vasoconstriction
  • Increased Na+ & H2O reabsorption into blood
  • INCREASES BP
42
Q

What do the Juxtaglomerular apparatus cells do in (RAAS)

A
  • They monitor BP in the arterioles.

- They begin the system when they detect low BP.

43
Q

What do the JG Cells do when they detect low bp in the arterioles?

A

They release renin

44
Q

What does renin do?

A

It converts angiotensinogen into angiotensin I

45
Q

What is angiotensiongen?

A

A plasma protein made by the liver

46
Q

Is angiotensin I activated?

A

No it’s still not able to do anything..

47
Q

Where is angiotensin converting enzyme found?

A

Found in the lungs

Secreted by the capillaries

48
Q

What does ACE do to angiotensin I?

A

It activates it to angiotensin II

49
Q

What does angiotensin II do?

A

1) It causes vasoconstriction

2) Causes aldosterone to be released from the adrenal cortex

50
Q

Where is aldosterone released from?

A

Adrenal cortex

51
Q

What does aldosterone do?

A

It acts on kidneys distal convoluted tubules so they will reabsorb more Na+ and H2O into the blood to increase BP

52
Q

What is tissue perfusion

A

the delivery of arterial blood to capillary bed in tissues

53
Q

what is tissue perfusion effected by? (2)

A

1) Cardiac output

2) Blood pressure

54
Q

What does a precapilary sphincter do?

A

Dialate/constrict smooth muscle to distribute blood to certain choose capillary beds

55
Q

Is blood velocity the same in every vessel?

A

No.. it varies

56
Q

Where is the velocity highest?

A

In large vessels and in arteries

57
Q

How does pressure effect velocity?

A

Increased pressure = increased velocity

58
Q

Where is blood velocity lowest?

A

In capillaries (b/c high SA & high PR)

59
Q

What is the relationship of velocity and cross-sectional area

A

it is inversely related

60
Q

What is capillary exchange?

A

Material exchanged between ECF of tissues and capillaries

61
Q

What is ICF?

A

intracellular fluid (w/ in the cell)

62
Q

Where is interstitial fluid found?

A

around/between the cells

63
Q

Why are capillaries the perfect place for exchange? (4)

A

1) Thin walls
2) Increased SA (surface area)
3) Increased permeability
4) decreased velocity

64
Q

What things are exchanged?

A

Nutritents, electrolytes, gases, wastes, hormones, water, heat

65
Q

what is capillary exchange driven by

A

concentration & pressure gradients

66
Q

What is bulk flow

A

Movement of fluid & small dissolved molecules

67
Q

What is CHP

A

Capillary hydrostatic pressure (BP pushes fluid and solute out of capillary)

68
Q

what is BCOP

A

blood colloid osmotic pressure

69
Q

what is colloid

A

proteins in plasma (pull fluid into capillaries via osmosis)

70
Q

BP pushes H2O…

A

out

71
Q

Osmosis pulls H2O…

A

in

72
Q

What is NFP

A

Net filtration pressure (CHP - BCOP)

73
Q

Does the BCOP change?

A

No

74
Q

What is edema

A

swelling, fluid in interstitial spaces

75
Q

What happens at the beginning of a capillary bed

A

The capillary loses fluid

76
Q

What happens at the end of a capillary bed?

A

The capillary gains fluid that is pulled back in