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Physiology > Let 15 Blood Volume , BP > Flashcards

Let 15 Blood Volume , BP Flashcards

(51 cards)

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1
Q

CO is what?

A 
Cardiac Output (CO), is the volume of blood pumped/min by each ventricle 
-(SV)(HR)
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2
Q

Define stroke volume

A

SV is blood pumped/beat by each ventricle

- CO=SVxHR thus at rest, CO= about 5500ml/min=5.5L

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3
Q

What is about the total blood volume in the body

A

about 5.5L

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4
Q

what is the main controller of HR

A

the Autonomic innervation of SA node b/c nerve fibers modify rate of spontaneous depolarization

  • symp (increases HR)
  • parasymp (decreases HR)
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5
Q

what stimulates the opening of pacemaker HCN channels

A

NE & Epi

-this depolarizes SA faster, increasing HR

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6
Q

What promotes opening of K+ channels

A

ACh, the resultant k+ outflow counters Na+ influx, slowing depolarization & decreasing HR

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7
Q

Cardiac control center of medulla does what

A

coordinates activity of autonomic innervation

-sympathetic endings in atria &ventricular can stimulate increased strength of contraction

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8
Q

What 3 variables determine SV

A
  • End diastolic volume(EDV)
  • Total peripheral resistance(TPR)
  • Contractility
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9
Q

Define EDV

A

volume of blood in ventricles at end of diastole; increase EDV= incr SV; dear EDV=decr SV

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10
Q

define TPR

A

impedance to blood flow in arteries; increase TPR= decreased SV; decreased TPR= increased SV

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11
Q

define contractility

A

strength of contraction decreases contractility=decreased SV

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12
Q

what is workload(preload)

A

EDV is amount of blood in ventricles just before they contract

  • SV is directly proportional to preload & contractility
  • strength of contraction varies directly with EDV
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13
Q

afterload which impedes ejection from ventricle comes from what

A

TPR

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14
Q

Frank-Starling Law of the Heart says what

A

states that strength of ventricular contraction varies directly with EDV
- when EDV increases, strength of ventricular contraction increases, thus SV increases

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15
Q

at any given EDV, strength of contraction depends upon level of what activity?

A

sympathoadrenal activity= positive inotropic effect; NE & Epi produce an increase in HR & contraction

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16
Q

Effect on SV is what effect

A

inotropic (positive)

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17
Q

what are the 2 ways CO is affected by sympathoadrenal activity

A
  1. positive inotropic effect on contractility

2. positive chronotropic effect on HR

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18
Q

effect on HR is what effect

A

positive chronotropic effect

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19
Q

what is venous return

A

return of blood to heart via veins

  • controls EDV & thus SV & CO
  • dependent upon total blood volume & venous pressure
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20
Q

what percentage of blood do veins hold

A

about 70% & are called capacitance vessels

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21
Q

describe capacitance vessels

Study These Flashcards
A

they have thin walls & stretch easily to accommodate more blood w/o increased pressure (higher compliance)
-have only 0-10 mmHg pressure vs. arteriole pressure of 90-100mmHg

22
Q

venous return is aided by what ?

Study These Flashcards
A
  1. vasoconstriction caused by symp(smooth muscle contraction)
  2. skeletal muscle pumps (squeezes veins)
  3. pressure to drop during inhalation; promotes flow of venous blood to heart
23
Q

urine formation begins with what

Study These Flashcards
A

filtration of plasma in renal capillaries=glomeruli; filtrate passes thru & is modified by nephron
-volume of urine excreted can be varied by changes in reabsorption of filtrate

24
Q

ADH is released by what

Study These Flashcards
A

posterior pituitary when osmoreceptors in hypothalamus detect high osmolality

25
Aldoesterone
steroid hormone secreted by adrenal cortex
26
what does aldosterone do
helps maintain blood volume & pressure thru reabsorption & retention of salt &water release stimulated by salt deprivation, low blood volume, and low bp
27
when there is a salt deficiency, low blood volume or pressure what is produced
angiotensin 2
28
ANP is what
Atrial Natriuretic peptide - increase blood volume is detected by stretch receptors in left atrium - causes release of ANP hormone - inhibits aldosterone, promoting Na+ excretion & water excretion to lower blood volume, also promotes vasodilation - WORKS TO DECR. BP
29
vascular resistance to blood flow determines what
how much blood flows through a tissue or organ
30
vasodilation=
decrease resistance= increase blood flow
31
vasoconstriction =
increase resistance = decrease blood flow
32
how is bp regulated
by mainly controlling HR, SV, and TPR | -NOTE: CO=HRxSV thus BP=HRxSVxTPR
33
What is the baroreceptor reflex
it is activated by changes in BP; which is detected by baroreceptors located in aortic arch & carotid sinuses
34
no sound is heard during what flow
laminar flow= normal, quiet, smooth blood flow
35
Korotkoff sounds are heard when?
when the sphygmomanometer cuff pressure is greater than diastolic (lowest BP) but lower than systolic (highest bp) pressure
36
explain Korotkoff sounds
1st korotkoff sound is heard at pressure that blood is 1st able to pass thru cuff; represents systolic pressure -last sound occurs when cuff pressure=diastolic pressure
37
when do the korotkoff sounds disappear
sounds are heard until cuff pressure equals diastolic pressure
38
define pulse pressure
systolic pressure- diastolic pressure | - rise in pressure from diastolic to systolic levels=reflects SV
39
define mean arteriole pressure (MAP)
represents average arterial pressure during cardia cycle - has to be approx b/c period of diastolic is longer than period of systole - MAP = pulse pressure/3 + diastolic pressure
40
what is hypertension
abnormally high bp
41
what causes primary/essential hypertension
caused by complex & poorly understood mechanisms
42
what causes secondary hypertension
caused by unknown disease processes
43
primary/ essential hypertension is what
about 95% of high bp cases; CO & HR are elevated in many | - kidneys appear to be unable to properly excrete Na+ & H20
44
Dangers of hypertension
- patients usually asymptomatic until vascular damage occurs -contributes to atherosclerosis, increases workload of the heart leading to ventricular hypertrophy & congestive heart failure, often damages cerebral blood vessels leading to stroke. "silent killer"
45
treatment of hypertension
- lifestyle changes, ex; cessation of smoking, decrease in alcohol intake, weight reduction..etc - drug treatments: diuretics to reduce fluid volume, beta blockers to decrease HR, calcium blockers...etc
46
what is circulatory shock
occurs when there is inadequate blood flow to & or 02 usage by tissues - cardiovascular system undergoes compensatory changes - sometimes shock becomes irreversible & death ensues
47
other causes of circulatory shock
- severe allergic rxn= rapid fall in bp called anaphylactic shock - rapid fall in bp called neurogenic shock can result from decrease in simp tone following spinal cord damage or anesthesia - cariogenic shock; is common following cardiac failure
48
what is septic shock
refers to dangerously low bp resulting from sepsis(infection); mortality rate (50-70%) - often occurs as a result of endotoxin release from bacteria
49
what does endotoxin do
induces NO production causing vasodilation & resultant low bp - treatment:drugs inhibiting production of NO
50
what is hypovolemic shock
circulatory shock caused by low blood volume - ex; hemorrhage, dehydration, or burns - decreased BP and CO - results in low bp, rapid pulse, cold clammy skin, low urine output
51
what is congestive heart failure
occurs when CO is insufficient to maintain blood flow - caused by myocardial infraction, congenital defects, hypertension, aortic valves stenosis, disturbance in electrolyte levels

Physiology (6 decks)

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