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PHYSIOLOGY > CARDIOVASCULAR SYSTEM > Flashcards

CARDIOVASCULAR SYSTEM Flashcards

1
Q

what is the area of the heart that contracts from one stimulation event?

A

myocardium/ functional syncytium

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2
Q

what is the pacemaker of the heart?

A

Sino atrial node (SA node)

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3
Q

what is the bundle of His?

A

specialized muscle cells for electrical conduction

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4
Q

what do the bundle of His branch into as they go on to stimulate the ventricles?

A

Purkinje Fibers

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5
Q

why is the SA node considered to be self-excitatory?

A

Sodium ion naturally leak into the node, thus causing depolarization

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6
Q

what are the 3 phases of the pacemaker potentials?

A
  1. Pacemaker potential
  2. Depolarization [ calcium influx]
  3. Repolarization [potassium efflux]
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7
Q

what are the 2 sympathetic activities used to modulate the rate at which SA node depolarizes?

A
  1. chronotropic [ increase rate of SA node discharge - decrease delay at AV node ] = beta 1 receptors
  2. ionotropic [ increase force of contractility= Beta 2 receptors]
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8
Q

what are the differences in membrane potentials of the SA fiber and the ventricular fiber?

A

SA fiber= discharges between -55 and -60

Ventricular fiber = discharges between -85 and -90

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9
Q

why is the action potential prolonged in cardiac muscle?

A
  1. fast sodium channels and slow calcium channels= prolonged plateau
  2. onset of AP decreases potassium permeability, therefore takes longer to repolarize
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10
Q

how is calcium reduced from the sarcoplasm?

A

reduced by active transporters or is extruded by the Na+ Ca2+ exchanger

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11
Q

is the T-tubule in cardiac muscle greater than that in skeletal muscle?

A

yes

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12
Q

what does the ECG not record?

A
  1. action potentials

2. contraction or relaxation

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13
Q

when do the ‘lub’ and ‘dub’ occur?

A 
lub= after the QRS wave when the atrioventricular valves close 
dub= at beginning of T wave when semilunar valves close
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14
Q

what is arrythmias?

A

irregular or abnormal heart beat rhythm

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15
Q

what is the difference between flutter and fibrillation?

A

Flutter: fast contractions that are coordinated

Fibrillation: uncoordinated contractions between the atria and ventricles

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16
Q

give two causes and result of atrial fibrillation

A
  1. cause= atrial flutter
  2. cause= atrial muscles not contracting well
  3. result= thrombi, stoke , heart attack
  4. reduction of blood output by 15%
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17
Q

give 2 cause of ventricular fibrillation and result

A
  1. cause: ventricles cant pump blood out
  2. cause: Circus Rhythms
  3. result: sudden death
  4. result: prevented refractory period
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18
Q

how is damage to the AV node seen on ECG graph

A

changes in P-R segment

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19
Q

briefly describe the degrees of AV node blockage?

A
  1. impulse conduction exceed 0.2 secs
  2. not every electrical wave is transmitted
  3. no stimulation present, Purkinje fiber pace makers do the job, but is slow.
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19
Q

briefly describe the degrees of AV node blockage?

A
  1. impulse conduction exceed 0.2 secs
  2. not every electrical wave is transmitted
  3. no stimulation present, Purkinje fiber pace makers do the job, but is slow.
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19
Q

briefly describe the degrees of AV node blockage?

A
  1. impulse conduction exceed 0.2 secs
  2. not every electrical wave is transmitted
  3. no stimulation present, Purkinje fiber pace makers do the job, but is slow.
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20
Q

what are the 3 tunics of the blood vessels?

A
  1. tunic externa [connective tissue]
  2. tunic media [smooth muscle]
  3. tunic interna [simple squamous epithelium with elastic fibers]
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21
Q

name the 3 types of arteries?

A
  1. elastic arteries
  2. muscular arteries
  3. arterioles
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22
Q

which type of arteries produce the greatest resistance and why?

A

arterioles because they have the smallest lumina

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23
Q

how is the blood flow to the capillaries regulated?

A
  1. vasoconstriction and vasodilation by smooth muscle

2. precapillary sphincters

24
Q

name the 3 types of capillaries

A
  1. continuous capillaries
  2. fenestrated capillaries
  3. discontinuous capillaries
25
Q

where can fenestrated capillaries be found?

A

kidneys. intestines

26
Q

where can discontinuous capillaries be found?

A

bone marrow, liver, spleen

27
Q

where can continuous capillaries be found?

A

muscle, adipose tissue and CNS

28
Q

compare the lumen, pressure, thickness of arteries and veins

A

veins have a larger lumen, veins have thinner walls, veins contain less blood pressure, veins collapse when cut

29
Q

what are the 3 mechanisms veins use to return blood back to the heart?

A
  1. BREATHING: inhalation= flattening of diaphragms, therefore there is greater abdominal pressure than thoracic pressure, thus pushing blood back up to the heart.
  2. VENOUS VALVES: flow in one direction
  3. SKELETAL MUSCLE PUMPS: muscles surrounding the veins
30
Q

what is arteriosclerosis?

A

hardening of the arteries

31
Q

what cause arteriosclerosis?

A

smoking, diabetes, high cholesterol, high blood pressure

32
Q

what role do LDL and VLDL play in arteriosclerosis?

A

the oxidization of these two compounds results in the formation of a plaque

33
Q

what do LDL’s do?

A

carry cholesterol to the arteries

34
Q

what do HDL’s do?

A

carry cholesterols away from the arteries to the liver for metabolism.

35
Q

how is maximum heart rate calculated?

A

MHR= 220- age

36
Q

what kind of drugs increase HDL levels in the blood stream?

A

Statin Drugs

37
Q

what is ischemia?

A

inadequate oxygen in somatic cells due to reduced blood flow

38
Q

what does Nitroglycerin do?

A

Causes vasodilation in both arteries and veins

39
Q

how can you detect ischemia on an ECG?

A

depression of the S-T segment

40
Q

what is the average resting heart rate?

A

60-75 bpm

41
Q

what is the difference between the stroke volume and the cardiac output?

A

Stroke Volume = the amount of blood pumped out the left ventricle per heart beat
Cardiac Output= the amount of blood pumped out the left ventricle per minute

42
Q

how is the pulse pressure calculated?

A

systolic pressure minus the diastolic pressure

43
Q

how is the Mean Arterial Pressure calculated?

A

diastolic pressure + 1/3 pulse pressure

44
Q

What is the value of a normal blood pressure in a healthy adult?

A

120/80 mmHg

45
Q

does vasoconstriction increase or decrease the total peripheral resistance?

A

increases

46
Q

what causes the Baroreceptors in the arteries to be stimulated?

A

stretching

47
Q

in which areas of the body are the baroreceptors most prevalent?

A
  1. carotid sinus [artery]

2. wall of aortic arch

48
Q

how does the signal travel from the carotid sinus to the medullary of the brain stem?

A

carotid sinus> Hering’s nerve> Glossopharyngeal nerve> Tractus Solitarius of medulla

49
Q

how does the signal travel from the aortic arch to the medulla

A

aortic arch> vagus nerves ( cranial nerve 10) > Tractus Solitarius of medulla> secondary signals inhibit vasoconstriction and excite the vagal parasympathetic system.

50
Q

what are chemoreceptors?

A

special nerve cells that sense changes in the chemical composition of blood

51
Q

why are the chemoreceptors stimulated when there is a decrease in arterial pressure?

A

reduced blood flow increases carbon dioxide levels, causes a decrease in oxygen levels and an excess of hydrogen levels, changes in the chemical composition of the blood are what stimulate the chemoreceptors to excite the vasomotor centers.

52
Q

when is a person considered to have low blood pressure?

A

when systolic blood pressure is below 100 mmHg

53
Q

where

A
54
Q

where is the enzyme Renin produced in the body?

A

kidneys

55
Q

where is the protein Angiotensinogen produced?

A

liver

56
Q

where is Angiotensinogen converting enzyme [ACE} found?

A

lungs

57
Q

what does A.C.E do?

A

coverts angiotensin 1 to angiotensin 2

58
Q

what does angiotensin 2 do?

A
  1. acts on adrenal glands to stimulate release of aldosterone
  2. triggers the production of ADH
  3. stimulates thirst centers= take in more water= increased of absorption of fluids= increased volume= increased stroke volume= increased cardiac output= increased BP
  4. causes vasoconstriction
59
Q

what does aldosterone do?

A

allows sodium to move into the blood, thus also retaining water in the bloodstream, increasing the blood pressure.

PHYSIOLOGY (3 decks)

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