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Engelking Phys Review > Section4. Cardiovascular physiology > Flashcards

Section4. Cardiovascular physiology Flashcards

1
Q

The pulmonary circulation normally contains what percentage of the total blood volume?

A

9%

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2
Q

The heart in diastole, normally contains about what percentage of the total blood volume?

A

7%

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3
Q

Which vessels contain the greatest amount of elastin?

A

aorta and pulmonary artery

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4
Q

Capillaries are generally more permeable on the arterial or venous end?

A

more permeable on the arterial end

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5
Q

The resting state red blood cell transit time from the arteriolar to the venular end of an average-sized capillary bed (70 kg mammal) is about?

A

1 to 2 seconds

(0.07 cm/second)

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6
Q

The velocity of blood flow normally reaches its lowest point in which vessels?

A

capillaries

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7
Q

B/c of Bernoulli, what relationship exists between blood velocity and pressure in the capillary bed?

A

IN a closed tube, such as a blood vessel, total energy must remain constant. Thus kinetic energy of flow plus pressure energy must remain constant. When applied to a narrow portion of a blood vessel- kinetic energy is increased as velocity increases and potential energy must be reduced

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8
Q

What is thought to be the primary determinant of resistance to blood flow in the vascular system?

A

the radius of blood vessels

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9
Q

What are factors that enhance lymph flow:

A

skeletal muscle contraction
rhythmic pumping action of lymphatic vessels
pulsations of arteries
suction pressure created within lympahtic vessels

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10
Q

The amount of lymph formed per day in the body is roughly equivalent to the

A

plasma volume

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11
Q

What is normal plasma volume?

A

4% of bodyweight

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12
Q

The colloid osmotic pressure is normally greatest in lymph collected from what organ?

A

The liver

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13
Q

Over one-half of the lymph formed in the body normally comes from which organs?

A

Liver and GIT

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14
Q

The lymphatic system is a major route of absorption of nutrients from the intestinal tract, being particular responsible for:

A

the absorption of dietary fat
–> chylomycrons are too large to enter the vascular system of the intestine, but are absorbed into lacteals of the lymphatic system

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15
Q

What are the causes of edema:

A
  1. increased capillary pressure d/t venular constriction or increased venous pressure (ie: heart failure, venous obstruction, etc)
  2. decreased oncotic pressure gradient across capillaries (ie: decreased plasma protein concen d/t nephrosis)
  3. increased capillary permeability d/t histamine, kinins or related substances
  4. inadequate lymph flow
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16
Q

What factors are known to cause increased cerebral blood flow?

A

-CSF H concen increases (cerebral blood vessels dilate)
-INC in perivascular K concen
-INC adenosine concen in brain tissue (inc d/t ischemia, hypoxemia, hypotension, electrical stim or seizures)

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17
Q

What are the two most known resistance vessels in the skin?

A

arterioles
arteriovenous anastomoses

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18
Q

Parasympathetic vasodilater nerve fibers do not supply cutaneous blood vessels, however, stimulates of:

A

sweat glands, which are innervated by cholinergic sympathetic fibers, results in vasodilation of skin resistance vessels

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19
Q

Splenic contraction is facilitated by:

A

alpha-adrenergic agents

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20
Q

Skeletal muscle accounts for what percentage of basal O2 consumption at rest?

A

20 to 30%

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21
Q

Under resting conditions, which organ, normally receives, per unit of weight, a greater blood flow than any other major organ in the body?

A

Kidney

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22
Q

During exercise, pulmonary vascular resistance

A

falls

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23
Q

SA node pacemaker activity is governed largely by:

A

magnitude of the initial resting membrane potential, the rate of depolarization and the threshold

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24
Q

What is the effective refractory period of the cardiac cycle is the:

A

period during which a stimulus, no matter how strong, fails to produce a propagated electrical response

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25
Q

define intercalated disk

A

entire, continuous stepwise boundary joining the end regions of adjacent cardiac mm cells

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26
Q

Dihydropyridine receptor on the T-tubule, functions as:

A

a voltage sensor in skeletal mm

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27
Q

The decreased early resting pacemaker preportential that causes faster heart rates is usually attributable to an altered ratio of intracellular to external (what electrolyte?

A

K

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28
Q

acetylcholine has what effect on the heart?

A

mild stimulus: slowing of heart rate, decreases strength of atrial contraction and marked reduction of conduction velocity through AV node

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29
Q

The first heart sound of the cardiac cycle heard with a stethoscope is

A

is caused by oscillation of blood in the ventricular chambers and vibration of the chamber walls

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30
Q

The second heart sound of the cardiac cycle occurs with

A

closure of the semilunar valves

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31
Q

What conditions increase intensity of the second heart sound?

A

pulmonary or systemic hypertension

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32
Q

The third heart sound of the cardiac cycle is associated with

A

rapid inflow of blood into the ventricles

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33
Q

Left ventricular isometric contraction involves

A

a period of rising tension in the ventricles, however there are no changes in intraventricular volume

34
Q

Cardiac valve closure occurs when

A

pressure in the distal chamber exceeds that in the proximal chamber
**opening of semilunar valve by rise of pressure in ventricle
** fall of pressure in the distal chamber–opening of mitral and tricuspid valves

35
Q

What is the normal end-ventricular systolic volume (ie. residual volume)?

A

at rest is about equal t o the ejected during systole

36
Q

Is atrial contraction essential for normal ventricular filling (at rest)?

A

No, since hte bulk of ventricular filling normally occurs before strial systole

37
Q

What percentage of total blood inflow into the coronary circulation normally enters the right coronary artery of dogs?

A

15%

38
Q

Describe coronary blood flow

A

-onset of isometric ventricular contraction, coronary blood flow falls abruptly
-opening of aortic calve and systolic inc in aortic pressure, coronary flow rises to a mod peak then fall again
-closure of the aortic valve, coronary flow rises to a maximum, to again decline slowly during diastole

39
Q

What percentage of oxygen in coronary blood is normally removed by the heart

A

70%

40
Q

In the postabsorptive state the principle fuel used by myocardial cells is:

A

fatty acids

41
Q

What is the effective circulating volume?

A

reflects the adequacy of tissue perfusion
-related directly to the fullness of and pressure within the vascular tree, and under normal circumstances varies directly with ECF volume

42
Q

Of the mechanoreceptors within the body, which one is considered to be low-pressure baroreceptors that primarily sense fullness of the vascular tree rather than the pressure therein?

A

atrial stretch receptors

43
Q

An increase in heart rate is sometimes produced by large intravenous infusion of saline or blood. This “Bain bridge reflex” is caused by:

A

the firing of type A high-pressure baroreceptors in atria of the heart

44
Q

Which of the cranial nerves are considered buffer nerves? (which nerves receive input from aortic arch and carotid sinus baroreceptors and send info to hypothalamic and medullary centers via)

A

X: vagus
IX: glossopharyngeal

45
Q

What occurs when sensory input from baroreceptors decreases:

A

sympathetic outflow to the heart and blood vessels increases

46
Q

Where is the cardiovascular control center located?

A

medulla of the brain stem

47
Q

The cardiovascular control center is tonicallya ctive system that is inhibited by input from baroreceptors through which cranial nerves?

A

IX: glossopharyngeal: innervates the carotid sinuses

X: vagus: innervates the aortic arch and low pressure volume receptors in the atria and pulmonary circulation

48
Q

When sensory input to from baroreceptors decreases, as it does when arterial pressure decreases, how does the sympathetic/parasympathetic system respond?

A

sympathetic outflow from hypothalamus to heart and blood vessels increases

parasympathetic outflow from the hypothalamus to the heart decreases

ANS: helps to oppose a fall in arterial pressure and restore both blood pressure and volume

49
Q

When sensory input to baroreceptors increases, as it does when arterial pressure increases, how does the sympathetic/parasympathetic system respond>

A

Sympathetic outflow to heart and blood vessels decreases

parasympathetic outflow increases

50
Q

What is the ultimate effect of atrial natriuretic peptide?

A

rapidly increases excretion of NaCl and water by the kidneys

51
Q

What are the effects of ANP on the kidney?

A

-vasodilates afferent and vasoconstrict efferent arterioles of the kidney (INC GFR)
-decreases renin secretion by juxtaglomerular cells of afferent arterioles (indirect actions on angiotensin II and II concentrations)– dec peripheral resistance and dec aldosterone release from adrenal cortex
-dec ability of ADH to act on medullary collecting ducts of the kidney

52
Q

arterial receptors that respond to changes in the PCO2, PO2 and pH of blood are found in specialized tissues near

A

aortic archa dn carotid bifurcations

53
Q

When arterial chemoreceptors are stimulated in the carotid arteries, what are the response?

A

they respiratory response is greater, evoking pulmonary hyperventilation and secondarily inc in heart rate

54
Q

In normal adult mammals, what is the average blood volume (ml/kg bwt) is about?

A

75 ml/kg

55
Q

Following hemorrhage, what control mechanism for restoration of blood volume is considered to be the most importantly quantitatively?

A

capillary fluid shift

56
Q

plasma compartment (iin % bwt) in comparison to interstitial fluid compartment?

A

16% bwt: interstitial fluid compartment

4% bwt: plasma compartment

57
Q

How do red blood cells gain energy?

A

anaerobic glycolytic pathways
&
heoxse monophosphate shunt that produces NADPH for glutathione reduction (defense mech against oxidative stress)

58
Q

What is the principle component of the red cell, that makes up about 95% of the dry weight of the cell?

A

hemoglobin

59
Q

Erythropoiesis requiries all of the following minerals/vitamins

A

copper
cobalt
iron
folic acid and pyridoxine

60
Q

What is the effect of lead on erythropoiesis?

A

inhibits conversion of delta-aminoleculinate to porphobilinogen toin heme biosysntehsis, therefore resulting ind ecreases erythropoiesis and anemia

61
Q

Why is ceruloplasmin important in erythropoiesis?

A

-copper containing protein iof plasma
-is a ferroxiase and appears ot be necssary for transfer of irone from reticuloendothelial cells to plasma transferrin

62
Q

Methemoglobin reductase of mature erythrocytes uses what molecule from anaerobic glycosis?

A

NADH

**does not use NADPH

63
Q

What is methemoglobin

A

an inactive form of hemoglobin in which the iron is oxidzed from teh ferrous to feric state by superoxides that are normally rpesent in RBCs

64
Q

What is the importance of methemoglobin reductase?

A

important in keeping iron in its active state (since only heme iron in the ferrous form can carry oxygen reversibly)

65
Q

The Rapoport shunt is the source of

A

2,3-diphosphoglycerate in erythrocytes

66
Q

What is the importance of the Rapoport shunt in RBCs?

A

It allows for glycolysis to prcoeed when the need for ATP is minimal

67
Q

What are the effects of leukotrienes released from white blood cells?

A

-contraction of smooth mm
-cause vascular permeability to increases
- important regulators in many dzes involving inflammatory or immediate hypersensitivity reactions

68
Q

Thromboxane A2 is synthesizes in and causes

A

platelets

causes vasoconstriction and plt aggregation

69
Q

Prostacycline is produces where and causes

A

releases from endothelial cells of blood vessel wall

promotes vasodilation and inhibits plt aggregation

70
Q

Which is the strongest plt aggregator?

A

thromboxane A2

71
Q

platelets are known to release which compound to ahsten blood coagulation?

A

thrombopalstin

72
Q

Adenosine release from platelets helps to

A

facilitate plt aggregation

73
Q

Aspiring irreversibility inhibits

A

platelet cyclooxygenase and thus formation of thromboxane A2

74
Q

What is the key step in blood coagulation?

A

conversion of fibrinogen to fibrin by thrombin

75
Q

blood clotting via the extrinsic pathway is initiated by

A

tissue damage and relase of tissue thromboplastin

76
Q

Blood clotting via the intrinsic pathway is initiated by

A

exposure of blood to damaged endothelium or a negatively charged surface

77
Q

What is the most important cofactor for blood coagulation (electrolyte)?

A

Calcium

78
Q

What is an endogenous (active) proteolytic enzyme known to liquefy blood clots?

A

plasmin

79
Q

Which anticoagulant is know to inhibit synthesis of vitamin K dependent factors involved in blood coagulation?

A

dicumarol

80
Q

How are the anticoagulant effects of citrate and oxalate peformed?

A

through removal of calcium fro solution

Engelking Phys Review (5 decks)

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