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EKG & Physiology > Circulation Phys > Flashcards

Flashcards in Circulation Phys Deck (121):
1

Circulation
- 2 functions
- 2 circuits

1. pick up nutrients and deliver to tissues
2. pick up waste and deliver for excretion

- pulmonary and systemic circuit

2

Define flow

volume per unit of time

3

hemodynamics definition

physics of blood flow

4

What two things are blood flow dependent on

resistance
pressure

5

What is blood flow directly proportional to?

pressure divided by resistance
- flow proportionate to pressure
- flow is inversely proportionate to resistance

Q = (P1-P2)/R
P1 is arterial pressure
P2 is venule pressure

6

normal blood flow is called

laminar

7

How does blood flow near the lamina

slowly or not at all

8

Where does blood flow fastest in the vessel

center

9

probability of turbulence is related to what two things

- diameter of vessel
- viscosity of fluid

10

what happens to blood flow at vessel branches

- interrupted laminar flow
- increased likelihood of atherosclerotic plaque formation

11

What is a Bruit

auscultation of the sound of turbulent blood beyond a site of constriction

12

why is turbulence of blood bad

creates damage to tissues
- tissues really want to be repaired
- repair = plaque

13

shear stress define

frictional force placed on the vessel wall
- dependent on the area
- shear stress = force/area

14

What happens after acceptable amount fo stress of vessel wall is exceeded

vessel deforms or changes

15

how is shear stress detected?

endothelium has stress detectors which activate factors that cause repair (plaque formation)
- normal to develop plaque all through life, just a normal response to damage

16

5 factors that cause shear stress

1. growth factor
2. CAM (cell adhesion molecule - an adhesion molecule)
3. NOS (nitrous oxide synthase - leads to platelet aggregation
4. ACE - vasoconstriction
5. Tissue factor/thrombomodulin - procoagulation

* increase these flair signals, increase repair, increase plaque formation

17

Define blood velocity

displacement per unit of time

18

What is blood velocity proportional to

flow/area
- bigger diameter, faster flow, greater velocity

19

what does flow equal

(area)(velocity)

20

Velocity in
- aorta
- capillaries
- veins
- vena cava

- high
- slow
- speeding up
- even faster but not as fast as aorta

21

Plasma and blood viscosity

plasma: 1.8X viscosity of water
blood: 3-4X viscosity of water

22

effects of small vs. large changes in viscosity of blood
- examples of increased and decreased viscosity siutaitons

- small has very little effect, large change can make a difference
- severe anemia - decrease viscosity
-polycythemia - viscous blood

23

Resistance determined by

- vascular resistance (blood vessel radius)
- viscosity of blood (less of an effect than radius)

24

Which of the two resistance factors can be easily modified

vascular resistance - change artery diameter

25

in what situation can blood viscosity affect circulation

very high hematocrit

26

What would happen if capillaries lose too much intraluminal pressure?

will collapse if blood pressure in vessel drops below critical closing pressure

27

what two things help regulate pressure in capillaries?

- arterioles
- pre-capillary sphincters

**not smooth muscle bc capillaries don't have it!

28

Law of LaPlace

tension in the wall of a cylinder is directly proportional to the pressure across the wall and the radius

29

Do larger arteries withstand more or less wall tension than other vessels?

MORE

30

What do larger arteries have to protect them from high pressure

- thicker
- layer of CT, provides a sort of tunic
*preventing aneurysm

31

What physical property of capillaries help prevent rupture

small size

32

Where in the vascular system is the majority of blood

veins (54%)

33

High pressure portion of circulatory system
- name
- three types

resistance vessels
- aorta
- arteries
- arterioles

34

Low pressure portion of the circulatory system
- name
- three types

Capacitance vessels
- veins
- venules
- capillaries

35

Blood pressure reminder

- when cuff is inflated, stops arterial blood flow, no sound
- when released enough to let blood through, it's turbulent so hear Korotkoff sounds
- once artery is no longer compressed, no more turbulence, no more sounds

36

Pulse pressure
- def
- what does it represent

- diff between systolic and diastolic pressure
- represents the force the heart generates each time it contracts

37

What do both pulse pressure and systolic pressure represent

gauge of "arterial age"

38

What is risk in men with pulse pressure of 70 mmHg or greater

triples heart attack risk vs. pulse pressure of 50 mmHg or less

39

Wide pulse pressure
- when normal
- when abnormal

- exercise
- heart dz, HTN, ateriosclerosis

40

Narrow pulse pressure
- define %
- 3 ex

- <25% systolic pressure
- aortic stenosis, cardiac tamponade, heart failure

41

What happens to both systolic and diastolic pressure as age

increases even in absence of HTN, pulse pressure will remain teh same

42

What happens as age and arteries become more resistant

Diastolic pressure can decrease in an effort to reduce effects of afterload

43

Mean arterial pressure
- define
- what does it mean

- average pressure during cardiac cycle
- relates to adequate perfusion of tissues

44

How to calc mean arterial pressure

diastolic pressure + 1/3 pulse pressure

45

Greater than what mean arterial pressure will sustain organs

>70 mmHg
normally between 65-110 mmHg

46

How does gravity affect arterial pressure

- return to the heart from below (IVC) requires more pressure bc of gravity
- pressure in arteries below heart is increased compared to those above heart

47

Capillary pressure
- arterial end
- venous end
- transit time from a to v

- arterial: 32 mmHg
- venous: 15 mmHg
- 1-2 seconds
* blood flows across capillary bc it's pushed from arterial side and pulled from venous side

48

How do gases cross membranes

diffusion down pressure gradient

49

what is the name of the forces that affect filtration in capillaries

Starling Forces

50

Starling forces are what two pressures

- Hydrostatic pressure
- Oncotic pressure

51

Hydrostatic pressure

- aka osmotic pressure
- causes water and solutes to flow from high to low pressur

52

Oncotic pressure

- aka colloid pressure
- water is drawn to area of higher colloid concentration
- blood has more protein than interstitial fluid, draws fluid into blood from interstitial

53

Filtration at the arterial end of capillary

- strong hydrostatic pressure (32 mmHg)
- osmotic pressure of 22 mmHg
- net pressure is out of blood (10 mmHg)

54

Filtration at the venous end of capillary

- weaker hydrostatic pressure (15 mmHg)
- osmotic pressure 22 mmHg
- net pressure into blood (-7 mmHg)

55

Venous pressure
- gravity affects
- velocity

- gravity increases pressure below the heart
- velocity is slower than arteries due to larger radius

56

pressure of great veins vs. aorta

great veins: 10 cm/s
aorta: 40 cm/s

57

why does venous return to the heart require aid (3)

lower pressure
gravity
slowed velocity

58

What three factors aid venous return to the heart

- heart
- thoracic pump
- muscle pump

59

How does the heart aid venous return

- during ventricular systole, atrial pressure decreases
- sucks blood into atria

60

How does the thoracic pump aid venous return

- during inspiration create negative intrathoracic pressure
- positive abdominal pressure due to compression of abdominal organs by diaphragm
- pressure gradient between infra- and supradiaphragmatic parts of IVC
- pulls blood toward right atrium!

61

How does muscle pump aid venous return

- rhythmic contraction of skeletal muscle in limbs propels blood toward heart
- venous valves prevent retrograde flow

62

sympathetic and parasympathetic supply to majority of vasculature

sympathetic only!

63

Describe overview of SNS innervation

- SNS adrenergic fibers terminate on vascular smooth muscle
- mediates vasoconstriction via alpha adrenergic receptors

64

What four types of tissue does parasympathetic system have vascular control

- erectile tissue
- salivary glands
- some facial vessels
- uterine vessels

65

Three types of adrenergic receptors found in blood vessels

- alpha 1 (constriction)
- alpha 2 (constriction)
- beta 2 (dilation)

alphas are majority

66

2 types of adrenergic receptors found in heart

- beta 1 (tachycardia, increased contractility)
- alpha 1 (increased contractility)

67

Alpha 1 receptor effects in vascular system

- vasoconstriction
- increased peripheral resistance
- increased bp

68

alpha 2 receptor effects in vascular system

- inhibition of NE release
- inhibition of acetylcholine release

69

beta 1 receptor effects in vascular system

- tachycardia
- increased myocardial contractility
- increased renin release

70

beta 2 receptor effects in vascular system

- vasodilation
- slightly decreased peripheral resistance

71

SNS stimulation of the heart sends what neurotransmitter to B1 cells

NE

72

where are B1 cells located in heart

- SA node
- AV node
- His and Perkinje fibers
- atrial and ventricular contractile tissue

73

what is stimulated via SNS in cards

- heart rate
- rate of transmission of conductive tissue
- force of ventricular contraction

74

other term for heart rate

chronotropy

75

other term for rate of transmission of conductive tissue

dromotropy

76

other term for ventricular contraction

ionotropy

77

What nerve does the PNS use to innervate the heart

Vagus nerve

78

PNS stimulation via vagus nerve
- via what type of receptors
- 3 termination locations

- Ach to muscarinic receptors

1. SA node
2. AV node
3. Atrial muscle

79

Affect of PNS on cardio system

decreased:
- hr
- rate through AV node
- atrial contractility
- SNS activity
- inhibits NE release from SNS

80

What part of brain controls sympathetic affects on cardiovascular system

RVLM

Rostral ventrolateral medulla

81

How do axons of RVLM project

- via thoracolumbar tract (IML)
- activate pregan SNS nerves (motor)
- post gang fibers go to heart

82

2 things that directly stimulate the RVLM

- CO2
- hypoxia

83

effect of vasoconstriction on afterload

- increases by increasing blood pressure
- also increases venous return which increases CO

84

What part of the brain controls parasympathetic input to the heart

nucleus ambiguus in the medulla
- then dorsal motor nucleus of vagus nerve

85

What type of neurons are in the nucleus ambiguus

cholinergic preganglionic parasympathetic neurons - cardioinhibitory

86

PNS vs. SNS
- what is primary means of BP control

SNS
- constricts arterioles and increases chronotropic and inotropic input

87

What is the parasympathetic systems's main role in regulating the cardiovascular system

- inhibit the SNS
- vs. directly dial down functions of the system
- cannot vasodilate directly

88

what stimulates the PNS in the nucleus ambiguus

increase in blood pressure

89

Two types of receptors that help dictate neural control of cardio system

- baroreceptors
- peripheral chemoreceptors

90

Baroreceptors
- measure what
- located where

- stretch receptors
- carotid sinus
- aortic arch
- cardiopulmonary receptors: atrial walls and pulmonary circulation sites

91

what stimulates baroreceptors

distention

92

Neural path from baroreceptors

- afferent to medulla (sensory)
- caudalventrolateral medulla (CVLM) to inhibit RVLM (if bp is high, reduces SNS control)
- nucleus of tracts solitaires (NTS): excites vagal motor neurons

*high bp inhibit SNS
*low bp increase SNS

93

Two peripheral chemoreceptors

- carotid body
- aortic body

94

What do the peripheral chemoreceptors respond to (3)

- decreased pO2
- increased pCO2
- increased pH

95

Effect of chemoreceptor stimulation

- increased vagal activity to stimulate ventilation - increase O2
- increase catecholamine release from adrenal cortex to increase hr and cause vascoconstriction

96

10 things that accelerate HR

1. decrease activity of arterial baroreceptors (down bp)
2. increased activity of atrial stretch receptors (less venous return)
3. inspiration
4. excitement - YAY
5. anger
6. painful stimuli
7. hypoxia
8. exercise
9. thyroid hormones
10. fever

97

5 things slow heart rate

1. increased activity of baroreceptors (higher bp)
2. expiration
3. grief
4. stimulation of pain fibers in trigeminal nerve
5. increased intracranial pressure

98

Theory for local auto regulation of vasodilation

Metabolic theory of auto regulation
- metabolites accumulate in active tissue
- act as vasodilators
- get increased flow to active tissue via dilation

99

Vasodilator metabolites

1. decreased O2
2. increased CO2
3. lactate
4. histamine
5. adenosine
6. prostacyclin
7. bradykinin
8. NO

100

where is lactate found

skeletal tissue

101

histamine affect on vessels

increases capillary permeability

102

Adenosine

- not naturally made i body
- anti-arrhythmic agent
- vasodilates cardiac arterioles
- inhibits NE release

103

prostacyclin

- produced by endothelial cells
- pro-inflammation
- vasodilation (so tissue can get what it needs)

104

kinins

- inflammation mediators
- vasodilation
- bradykinin stimulates NO
- vasodilation = vascular permeability
- relaxes smooth muscle

105

NO

- converted from arginine in response to vasodilators such as bradykinin
- diffuses from endothelial cells
- vasodilation via relaxation of blood vessel smooth muscle

106

circulating vasodilators

- ANP and BNP
- natriuretic hormones

107

ANP

A type natriuretic peptide
- secreted by atrial myoctyes in response to high blood volume

108

BNP

B type natriuretic peptide
- secreted by ventricles in response to excessive stretching of cardiomyocytes

109

ANP and BNP two overall effects

1. decreased bp via volume change
2. vasodilation of vessels

110

ANP and BNP affect on kidneys

decreased sodium retention - water follows, decreases blood pressure

111

ANP and BNP affect on vessel diameter

vasodilation

112

myogenic theory of autoregulation

an intrinsic contractile response of smooth muscle to stretch
- as pressure increases, vessel walls distend
- increased wall tension stimulates vasoconstriction to reduce the radius (Law of LaPlace - wall tension proportionate to radius)
- maintains blood pressure and blood flow

113

Local endothelial vasoconstrictive secretions

Endothelin-1
- potent mediator of vasoconstriction
- might be increased in HTN

114

3 Systemic circulating vascoconstrictors

- Angiotensin II
- Vasopressin (ADH)
- Epinephrine

115

Angiotensin II process

- Angiotensinogen made by liver all the time
- Kidney detects decrease in perfusion, releases renin
- Renin converts angiotensinogen into angiotensin I
- ACE (increased by renin) converts angiotensin I to angiotensin II

116

What does production of angiotensin II cause

- vasoconstriction, increase in blood pressure
- directly increases SNS activity = increased epi release
- kidney retains water = increased blood volume/pressure

117

ADH
- where synthesized
- where stored and released
- type of hormone

- synth by hypothalamus
- stored/released by posterior pituitary
- peptide hormone

118

Action of ADH

1. constricts smooth muscle
2. increases blood volume

* increased blood volume, peripheral resistance, and blood pressure

119

how does ADH increase blood volume

- acts on kidney, causes water reabsorption

120

Epinephrine
- where produced
- what tissues does it affect
- what does it cause

- produced by SNS in adrenal medulla
- effects most tissues
- constriction = inc. hr and cardiac output
- increases renin production by kidney

121

List of things that cause vasoconstriction

1. SNS innervation
2. myogenic autoregulation
3. endothelial secretion of endothelin-1
4. Angiotensin II (potent)
5. vasopressin (ADH)
6. circulatory epinephrine