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EKG & Physiology > Circulation Phys > Flashcards

Circulation Phys Flashcards

1
Q

Circulation

  • 2 functions
  • 2 circuits
A
  1. pick up nutrients and deliver to tissues
  2. pick up waste and deliver for excretion
  • pulmonary and systemic circuit
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2
Q

Define flow

A

volume per unit of time

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3
Q

hemodynamics definition

A

physics of blood flow

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4
Q

What two things are blood flow dependent on

A

resistance

pressure

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5
Q

What is blood flow directly proportional to?

A

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

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6
Q

normal blood flow is called

A

laminar

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7
Q

How does blood flow near the lamina

A

slowly or not at all

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8
Q

Where does blood flow fastest in the vessel

A

center

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9
Q

probability of turbulence is related to what two things

A
  • diameter of vessel

- viscosity of fluid

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10
Q

what happens to blood flow at vessel branches

A
  • interrupted laminar flow

- increased likelihood of atherosclerotic plaque formation

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11
Q

What is a Bruit

A

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

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12
Q

why is turbulence of blood bad

A

creates damage to tissues

  • tissues really want to be repaired
  • repair = plaque
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13
Q

shear stress define

A

frictional force placed on the vessel wall

  • dependent on the area
  • shear stress = force/area
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14
Q

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

A

vessel deforms or changes

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15
Q

how is shear stress detected?

A

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

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16
Q

5 factors that cause shear stress

A
  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
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17
Q

Define blood velocity

A

displacement per unit of time

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18
Q

What is blood velocity proportional to

A

flow/area

- bigger diameter, faster flow, greater velocity

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19
Q

what does flow equal

A

(area)(velocity)

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20
Q

Velocity in

  • aorta
  • capillaries
  • veins
  • vena cava
A
  • high
  • slow
  • speeding up
  • even faster but not as fast as aorta
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21
Q

Plasma and blood viscosity

A

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

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22
Q

effects of small vs. large changes in viscosity of blood

- examples of increased and decreased viscosity siutaitons

A
  • small has very little effect, large change can make a difference
  • severe anemia - decrease viscosity
  • polycythemia - viscous blood
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23
Q

Resistance determined by

A
  • vascular resistance (blood vessel radius)

- viscosity of blood (less of an effect than radius)

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24
Q

Which of the two resistance factors can be easily modified

A

vascular resistance - change artery diameter

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25
Q

in what situation can blood viscosity affect circulation

A

very high hematocrit

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26
Q

What would happen if capillaries lose too much intraluminal pressure?

A

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

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27
Q

what two things help regulate pressure in capillaries?

A
  • arterioles
  • pre-capillary sphincters

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

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28
Q

Law of LaPlace

A

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

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29
Q

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

A

MORE

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30
Q

What do larger arteries have to protect them from high pressure

A
  • thicker
  • layer of CT, provides a sort of tunic
  • preventing aneurysm
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31
Q

What physical property of capillaries help prevent rupture

A

small size

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32
Q

Where in the vascular system is the majority of blood

A

veins (54%)

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33
Q

High pressure portion of circulatory system

  • name
  • three types
A

resistance vessels

  • aorta
  • arteries
  • arterioles
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34
Q

Low pressure portion of the circulatory system

  • name
  • three types
A

Capacitance vessels

  • veins
  • venules
  • capillaries
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35
Q

Blood pressure reminder

A
  • 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
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36
Q

Pulse pressure

  • def
  • what does it represent
A
  • diff between systolic and diastolic pressure

- represents the force the heart generates each time it contracts

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37
Q

What do both pulse pressure and systolic pressure represent

A

gauge of “arterial age”

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38
Q

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

A

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

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39
Q

Wide pulse pressure

  • when normal
  • when abnormal
A
  • exercise

- heart dz, HTN, ateriosclerosis

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40
Q

Narrow pulse pressure

  • define %
  • 3 ex
A
  • <25% systolic pressure

- aortic stenosis, cardiac tamponade, heart failure

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41
Q

What happens to both systolic and diastolic pressure as age

A

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

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42
Q

What happens as age and arteries become more resistant

A

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

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43
Q

Mean arterial pressure

  • define
  • what does it mean
A
  • average pressure during cardiac cycle

- relates to adequate perfusion of tissues

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44
Q

How to calc mean arterial pressure

A

diastolic pressure + 1/3 pulse pressure

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45
Q

Greater than what mean arterial pressure will sustain organs

A

> 70 mmHg

normally between 65-110 mmHg

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46
Q

How does gravity affect arterial pressure

A
  • 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
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47
Q

Capillary pressure

  • arterial end
  • venous end
  • transit time from a to v
A
  • 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
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48
Q

How do gases cross membranes

A

diffusion down pressure gradient

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49
Q

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

A

Starling Forces

50
Q

Starling forces are what two pressures

A
  • Hydrostatic pressure

- Oncotic pressure

51
Q

Hydrostatic pressure

A
  • aka osmotic pressure

- causes water and solutes to flow from high to low pressur

52
Q

Oncotic pressure

A
  • 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
Q

Filtration at the arterial end of capillary

A
  • strong hydrostatic pressure (32 mmHg)
  • osmotic pressure of 22 mmHg
  • net pressure is out of blood (10 mmHg)
54
Q

Filtration at the venous end of capillary

A
  • weaker hydrostatic pressure (15 mmHg)
  • osmotic pressure 22 mmHg
  • net pressure into blood (-7 mmHg)
55
Q

Venous pressure

  • gravity affects
  • velocity
A
  • gravity increases pressure below the heart

- velocity is slower than arteries due to larger radius

56
Q

pressure of great veins vs. aorta

A

great veins: 10 cm/s

aorta: 40 cm/s

57
Q

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

A

lower pressure
gravity
slowed velocity

58
Q

What three factors aid venous return to the heart

A
  • heart
  • thoracic pump
  • muscle pump
59
Q

How does the heart aid venous return

A
  • during ventricular systole, atrial pressure decreases

- sucks blood into atria

60
Q

How does the thoracic pump aid venous return

A
  • 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
Q

How does muscle pump aid venous return

A
  • rhythmic contraction of skeletal muscle in limbs propels blood toward heart
  • venous valves prevent retrograde flow
62
Q

sympathetic and parasympathetic supply to majority of vasculature

A

sympathetic only!

63
Q

Describe overview of SNS innervation

A
  • SNS adrenergic fibers terminate on vascular smooth muscle

- mediates vasoconstriction via alpha adrenergic receptors

64
Q

What four types of tissue does parasympathetic system have vascular control

A
  • erectile tissue
  • salivary glands
  • some facial vessels
  • uterine vessels
65
Q

Three types of adrenergic receptors found in blood vessels

A
  • alpha 1 (constriction)
  • alpha 2 (constriction)
  • beta 2 (dilation)

alphas are majority

66
Q

2 types of adrenergic receptors found in heart

A
  • beta 1 (tachycardia, increased contractility)

- alpha 1 (increased contractility)

67
Q

Alpha 1 receptor effects in vascular system

A
  • vasoconstriction
  • increased peripheral resistance
  • increased bp
68
Q

alpha 2 receptor effects in vascular system

A
  • inhibition of NE release

- inhibition of acetylcholine release

69
Q

beta 1 receptor effects in vascular system

A
  • tachycardia
  • increased myocardial contractility
  • increased renin release
70
Q

beta 2 receptor effects in vascular system

A
  • vasodilation

- slightly decreased peripheral resistance

71
Q

SNS stimulation of the heart sends what neurotransmitter to B1 cells

A

NE

72
Q

where are B1 cells located in heart

A
  • SA node
  • AV node
  • His and Perkinje fibers
  • atrial and ventricular contractile tissue
73
Q

what is stimulated via SNS in cards

A
  • heart rate
  • rate of transmission of conductive tissue
  • force of ventricular contraction
74
Q

other term for heart rate

A

chronotropy

75
Q

other term for rate of transmission of conductive tissue

A

dromotropy

76
Q

other term for ventricular contraction

A

ionotropy

77
Q

What nerve does the PNS use to innervate the heart

A

Vagus nerve

78
Q

PNS stimulation via vagus nerve

  • via what type of receptors
  • 3 termination locations
A
  • Ach to muscarinic receptors
  1. SA node
  2. AV node
  3. Atrial muscle
79
Q

Affect of PNS on cardio system

A

decreased:

  • hr
  • rate through AV node
  • atrial contractility
  • SNS activity
  • inhibits NE release from SNS
80
Q

What part of brain controls sympathetic affects on cardiovascular system

A

RVLM

Rostral ventrolateral medulla

81
Q

How do axons of RVLM project

A
  • via thoracolumbar tract (IML)
  • activate pregan SNS nerves (motor)
  • post gang fibers go to heart
82
Q

2 things that directly stimulate the RVLM

A
  • CO2

- hypoxia

83
Q

effect of vasoconstriction on afterload

A
  • increases by increasing blood pressure

- also increases venous return which increases CO

84
Q

What part of the brain controls parasympathetic input to the heart

A

nucleus ambiguus in the medulla

- then dorsal motor nucleus of vagus nerve

85
Q

What type of neurons are in the nucleus ambiguus

A

cholinergic preganglionic parasympathetic neurons - cardioinhibitory

86
Q

PNS vs. SNS

- what is primary means of BP control

A

SNS

- constricts arterioles and increases chronotropic and inotropic input

87
Q

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

A
  • inhibit the SNS
  • vs. directly dial down functions of the system
  • cannot vasodilate directly
88
Q

what stimulates the PNS in the nucleus ambiguus

A

increase in blood pressure

89
Q

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

A
  • baroreceptors

- peripheral chemoreceptors

90
Q

Baroreceptors

  • measure what
  • located where
A
  • stretch receptors
  • carotid sinus
  • aortic arch
  • cardiopulmonary receptors: atrial walls and pulmonary circulation sites
91
Q

what stimulates baroreceptors

A

distention

92
Q

Neural path from baroreceptors

A
  • 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
Q

Two peripheral chemoreceptors

A
  • carotid body

- aortic body

94
Q

What do the peripheral chemoreceptors respond to (3)

A
  • decreased pO2
  • increased pCO2
  • increased pH
95
Q

Effect of chemoreceptor stimulation

A
  • increased vagal activity to stimulate ventilation - increase O2
  • increase catecholamine release from adrenal cortex to increase hr and cause vascoconstriction
96
Q

10 things that accelerate HR

A
  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
Q

5 things slow heart rate

A
  1. increased activity of baroreceptors (higher bp)
  2. expiration
  3. grief
  4. stimulation of pain fibers in trigeminal nerve
  5. increased intracranial pressure
98
Q

Theory for local auto regulation of vasodilation

A

Metabolic theory of auto regulation

  • metabolites accumulate in active tissue
  • act as vasodilators
  • get increased flow to active tissue via dilation
99
Q

Vasodilator metabolites

A
  1. decreased O2
  2. increased CO2
  3. lactate
  4. histamine
  5. adenosine
  6. prostacyclin
  7. bradykinin
  8. NO
100
Q

where is lactate found

A

skeletal tissue

101
Q

histamine affect on vessels

A

increases capillary permeability

102
Q

Adenosine

A
  • not naturally made i body
  • anti-arrhythmic agent
  • vasodilates cardiac arterioles
  • inhibits NE release
103
Q

prostacyclin

A
  • produced by endothelial cells
  • pro-inflammation
  • vasodilation (so tissue can get what it needs)
104
Q

kinins

A
  • inflammation mediators
  • vasodilation
  • bradykinin stimulates NO
  • vasodilation = vascular permeability
  • relaxes smooth muscle
105
Q

NO

A
  • converted from arginine in response to vasodilators such as bradykinin
  • diffuses from endothelial cells
  • vasodilation via relaxation of blood vessel smooth muscle
106
Q

circulating vasodilators

A
  • ANP and BNP

- natriuretic hormones

107
Q

ANP

A

A type natriuretic peptide

- secreted by atrial myoctyes in response to high blood volume

108
Q

BNP

A

B type natriuretic peptide

- secreted by ventricles in response to excessive stretching of cardiomyocytes

109
Q

ANP and BNP two overall effects

A
  1. decreased bp via volume change

2. vasodilation of vessels

110
Q

ANP and BNP affect on kidneys

A

decreased sodium retention - water follows, decreases blood pressure

111
Q

ANP and BNP affect on vessel diameter

A

vasodilation

112
Q

myogenic theory of autoregulation

A

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
Q

Local endothelial vasoconstrictive secretions

A

Endothelin-1

  • potent mediator of vasoconstriction
  • might be increased in HTN
114
Q

3 Systemic circulating vascoconstrictors

A
  • Angiotensin II
  • Vasopressin (ADH)
  • Epinephrine
115
Q

Angiotensin II process

A
  • 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
Q

What does production of angiotensin II cause

A
  • vasoconstriction, increase in blood pressure
  • directly increases SNS activity = increased epi release
  • kidney retains water = increased blood volume/pressure
117
Q

ADH

  • where synthesized
  • where stored and released
  • type of hormone
A
  • synth by hypothalamus
  • stored/released by posterior pituitary
  • peptide hormone
118
Q

Action of ADH

A
  1. constricts smooth muscle
  2. increases blood volume
  • increased blood volume, peripheral resistance, and blood pressure
119
Q

how does ADH increase blood volume

A
  • acts on kidney, causes water reabsorption
120
Q

Epinephrine

  • where produced
  • what tissues does it affect
  • what does it cause
A
  • produced by SNS in adrenal medulla
  • effects most tissues
  • constriction = inc. hr and cardiac output
  • increases renin production by kidney
121
Q

List of things that cause vasoconstriction

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

EKG & Physiology (3 decks)

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