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BIOL 204 > Lecture 2 – Circ Sys II – ECG and blood vessels > Flashcards

Lecture 2 – Circ Sys II – ECG and blood vessels Flashcards

1
Q

the cardiac cycle:

systole and diastole –> which is contraction/relaxation?

A

systole –> contraction

diastole –> relaxation

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2
Q

LO: flow of blood in cardiac cycle:

what happens when ventricles relax?

  • pressure (drops/rises?) inside the ventricles
  • ___ close as blood attempts to back up into the ventricles from the vessels
  • AV valves (open/close)…why?
  • blood flows from ___ to ventricles
A

pressure drops inside the ventricles

semilunar valves close

AV valves open –> (when ventricles relax, pressure inside ventricles is less than inside atria. AV valves open so that atria can pump blood into ventricles to even out the pressure differences)

blood flows from atria to ventricles

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3
Q

LO: flow of blood in cardiac cycle:

what happens when ventricles contract?

  • AV valves (open/close?) as blood attempts to back up into atria
  • pressure (drops/rises) inside of the ventricles
  • semilunar valves (open/close?) and blood flows into great vessels
A

AV valves close

pressure rises inside of the ventricles

semilunar valves open and blood flows into great vessels

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4
Q

LO: coronary circulation –> describe the arteries that nourish the myocardium and the veins that draw it

why is coronary circulation necessary? what are the vessels that make up coronary circulation?

A

heart is a muscle and needs oxygen to sustain its workload. 5% of blood pumped by heart goes to the heart itself thru coronary circulation

right coronary artery

left coronary artery

coronary sinus

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5
Q

LO: describe the arteries that nourish the myocardium

what is angina pectoris?

A

chest pain from partial obstruction of coronary blood flow

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6
Q

LO: describe the arteries that nourish the myocardium

what is myocardial infarction (MI)?

A

sudden death of a patch of myocardium resulting from long-term obstruction of coronary circulation

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7
Q

LO: describe the unique structural and metabolic characteristics of cardiac muscle

cardiomyocytes (describe):
- striations?
- length?
- thickness?
- branching in cells?
- cell structure?

A

striated
short
thick
branched cells
one nucleus surrounded by light-staining mass of glycogen

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8
Q

LO: structure of cardiac muscle –> explain the nature and functional significance of the intercellular junctions b/n cardiac muscle cells

intercalated discs (describe)

A

join cardiomyocytes end to end w/ 3 features

(1) interdigitating folds – interlock and increase area of contact

(2) mechanical junctions – fascia adherent and desmosomes

(3) electrical junctions (gap junctions) – ions flow b/n cells; allow entire myocardium of either 2 atria or 2 ventricles to act like single, unified cell

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9
Q

LO: metabolism of cardiac muscle

cardiac muscle depends almost exclusively on ___ to make ATP

as such, cardiac muscle is rich in ___ and ___
cardiac muscle have (tiny/huge?) mitochondria that fill ~___% of cell

A

aerobic respiration

rich in myoglobin and glycogen

huge mitochondria –> fill 25% of cell

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10
Q

LO: metabolism of cardiac muscle

cardiac muscle metabolism is adaptable to different ___ ___, such as….

A

organic fuels

fatty acids (60%), glucose (35%), ketones, lactate, and amino acids (5%)

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11
Q

LO: metabolism of cardiac muscle

cardiac muscle is more vulnerable to ___ ___ than a lack fo a specific fuel

A

vulnerable to oxygen deficiency

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12
Q

LO: metabolism of cardiac muscle

is cardiac muscle easily fatigued?

A

no; does not fatigue for a lifetime

it mostly uses aerobic respiration and not anaerobic fermentation or oxygen debt mechanisms

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13
Q

LO: describe the heart’s pacemaker and electrical conduction system

what does the pacemaker and electrical conduction system do?

how much of the myocardium is made of this electrical conduction system?

A

coordinates heartbeat

~1% of the myocardium

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14
Q

LO: describe the heart’s pacemaker and electrical conduction system

what is the system composed of?

A

internal pacemaker (SA node) and nerve-like conduction pathways (made of modified cardiomyocytes) thru the myocardium

structures:
- Sino-atrial (SA) node
- atrioventricular (AV) node
- atrioventricular bundle
- interventricular septum
- right and left bundle branches
- Purkinje fibers

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15
Q

LO: describe the heart’s pacemaker and electrical conduction system

describe the steps:

A

(1) SA node fires

(2) excitation spread thru atrial myocardium

(3) AV node fires

(4) excitation spreads down AV bundle

(5) subendocardial conducting network distributes excitation thru ventricular myocardium

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16
Q

LO: explain why the SA node fires spontaneously and rhythmically:

cardiac rhythm:

what is the sinus rhythm?

what is ectopic focus?

A

normal heartbeat triggered by the SA node

a region of spontaneous firing other than the SA node

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17
Q

LO: explain why the SA node fires spontaneously and rhythmically:

describe pacemaker physiology

describe pacemaker potential:

A

SA node does not have a stable resting membrane potential

starts at -60 mV and drifts upward due to slow Na+ inflow

gradual depolarization is called pacemaker potential

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18
Q

LO: explain why the SA node fires spontaneously and rhythmically:

describe pacemaker physiology

describe pacemaker threshold and depolarization:

A

when SA node reaches threshold of -40 mV, voltage-gated fast Ca2+ and Na+ channels open

faster depolarization occurs, peaking at 0 mV

this generates an action potential –> allows SA node to fire –> sets of heartbeat (muscle contraction)

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19
Q

LO: explain why the SA node fires spontaneously and rhythmically:

describe pacemaker physiology

describe pacemaker repolarization:

A

depolarization peaks at 0 mV

K+ channels then open and K+ leaves cell –> causes repolarization

once K+ channels close, pacemaker potential starts over

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20
Q

LO: explain how the SA node excites the myocardium

A

SA node stimulates 2 atria to contract almost simultaneously

signal slows down thru AV node

signals travel very quickly thru AV bundle and subendocardial conducting network (Purkinje fibers)

ventricular systole (contraction) progresses up from apex

basically, signal goes down interventricular septum and then to outer walls of ventricles

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21
Q

LO: describe the unusual action potentials of cardiac muscle and relate them to the contractile behavior of the heart

electrical behavior of the myocardium:

A

depolarization:
(1) voltage-gated Na+ channels open

(2) Na+ inflow depolarizes the membrane and triggers the opening of still more Na+ channels, creating a positive feedback cycle and a rapidly rising membrane voltage

(3) Na+ channels close when the cell depolarizes, and the voltage peaks at nearly +30 mV

plateau:
(4) Ca2+ entering thru slow Ca2+ channels prolongs depolarization of membrane, creating a plateau. Plateau falls slightly because of some K+ leakage, but most K+ channels remain closed until end of plateau

repolarization:
(5) Ca2+ channels close and Ca2+ is transported out of cell. K+ channels open, and rapid K+ outflow returns membrane to its resting potential

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22
Q

the heartbeat is coordinated by the cardiac ___ system

A

conduction

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23
Q

in a healthy person at rest, the SA node normally fires about how many times per minute?

A

70-80

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24
Q

a spontaneously developing local potential that generates action potentials in the SA node is called what?

A

pacemaker potential

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25
Q

where does ventricular contraction begin?

A

apex

26
Q

Consider the phases of the action potential in a cardiocyte. After depolarization, contraction of the cardiocyte continues during the ___ phase of its action potential

A

plateau

27
Q

during which stage of an ECG does atrial systole occur?

A

PQ segment

28
Q

the QRS wave of an ECG represents what event in the heart?

A

depolarization of the ventricles

29
Q

what is a type of arrhythmia?

A

ventricular fibrillation

30
Q

depolarization of a cardiocyte is due to opening of which channels?

A

sodium

31
Q

the contraction of a cardiocyte occurs during which phase of its action potential?

A

plateau

32
Q

on an ECG, atrial systole begins during the ___

A

PQ segment

33
Q

the QRS wave of an ECG represents ___ of the ventricular myocardium

A

depolarization

34
Q

why is it important for conducting arteries to maintain elasticity?

A

their recoil helps maintain blood pressure b/n heartbeats

their expansion reduces systolic stress on smaller arteries

their expansion and recoil helps keep the blood flowing during diastole

35
Q

A weak, bulging sac in the wall of an artery that pulsates with each beat of the heart and which may eventually rupture is called a(n) ___

A

aneurysm

36
Q

which term refers to short vessels that link arterioles to capillaries?

A

metarterioles

37
Q

what are the small blood vessels that nourish the walls of larger vessels?

A

vasa vasorum

38
Q

sensory signals travel from aortic bodies to the brainstem via which cranial nerve?

A

vagus nerve

39
Q

where are carotid bodies located?

A

near the branch of the common carotid arteries

40
Q

which are chemoreceptors that are located in the aortic arch?

A

aortic bodies

41
Q

what are metarterioles and what do they do?

A

short vessels

in some places, metarterioles link arterioles to capillaries or provide shortcuts that bypass the capillaries

42
Q

sensory signals travel from heart to brainstem via which cranial nerve?

carotid bodies

aortic bodies

A

carotid bodies: arteries –> brainstem via glossopharyngeal nerves

aortic bodies: aortic arch –> brainstem via vagus nerves

43
Q

which are regarded as the capacitance vessels because they expand easily to accommodate an increased volume of blood?

A

veins

44
Q

arrange capillaries from most permeable to least:

A

sinusoids (most)
fenestrated
continuous (least)

45
Q

which refers to a circulatory route in which blood flows thru 2 consecutive capillary networks before returning to the heart?

A

portal system

46
Q

what best defines a capillary bed?

A

a network of capillaries supplied by a single arteriole or met arteriole

47
Q

which term can refer to a collateral route of blood supplied to a tissue?

A

anastomosis

48
Q

blood flow into capillary beds is regulated by smooth muscle structures called ___ sphincters which surround the openings to the capillaries

A

precapillary

49
Q

the type of blood vessel regarded as capacitance vessels are ___

A

veins

50
Q

rank types of veins from smallest to largest:

A

postcapillary veins
muscular venules
medium veins
venous sinuses
large veins

51
Q

where do portal systems occur?

A

b/n hypothalamus and anterior pituitary gland

kidneys

b/n intestines and liver

52
Q

an anatomical convergence where 2 blood vessels merge and combine their bloodstreams is known as a(n) ___

A

anastomesis

53
Q

components of ECG:

P wave:

A

atrial depolarization

54
Q

components of ECG:

P wave:

A

atrial depolarization

55
Q

components of ECG:

QRS complex:

A

ventricular depolarization

(also when atrial repolarization occurs)

56
Q

components of ECG:

T wave:

A

ventricular repolarization

57
Q

cardiac arrhythmias:

tachycardia vs. bradycardia

A

tachycardia – resting HR greater than 100 bpm

bradycardia – resting HR lower than 60 bpm

58
Q

what is stenosis?

A

when a valve is narrowed and doesn’t open properly

59
Q

what makes the lub sound?
which heart sound is it?

A

1st heart sound

AV (tricuspid and mitral) valves snap shut

(also semilunar pulmonary and aortic valves open)

60
Q

what makes the dub sound?
which heart sound is it?

A

2nd heart sound

semilunar (pulmonary and aortic valves) snap shut

(also AV valves open)

61
Q

in terms of lub/dub (or S1/S2), when does systole and diastole occur?

A

systole (ventricles contracting) occurs in b/n S1 and S2

diastole (ventricles relaxing) occurs in b/n S2 and the next S1

BIOL 204 (35 decks)

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