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Human physiology > cardiac output and regulation > Flashcards

cardiac output and regulation Flashcards

1
Q

what is cardiac output?

A

the amount of blood pumped by each ventricle in one minute

produce of heart rate and stroke volume

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2
Q

how do calulate cardiac output?

A

CO= HR X SV

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3
Q

what is stroke volume

A

amount of blood pumped out by a ventricle with each beat

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4
Q

what are the layers of the heart wall?

A

epicardium
myocardium
endocardium

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5
Q

what is the epicardium?

A

visceral layer of serous pericardium

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6
Q

what is pericardial fluid?

A

surronds the heart and protects it from compression

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7
Q

what is cardiac muscle?

A

fibres that wrap around the whole organ

contracts and twists to push blood out

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8
Q

why is the left side thicker?

A

higher pressure
systemic circulation here
more resistance

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9
Q

what is the coronary circulation?

A

supplies the heart with oxygen and nutrients

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10
Q

what are the two main branches of the left main coronary artery?

A

LAD

circumflex

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11
Q

what does the sympathetic nervous system do to the heart?

A

increases rate and force of contraction

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12
Q

what does the parasympathetic nervous system do to the heart?

A

slows heart rate

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13
Q

what does activation of the SAN do?

A

increases firing and thus heart rate too

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14
Q

what does the change in time lag of the cardiac cycle do?

A

allows blood to move from the atria to the ventricles

allows signal to move from the SAN to AVN

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15
Q

where are valves found in the heart?

A

2 atria ventricular valves

2 semilunar

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16
Q

what are the atria-ventricular vales?

A

mitral valves separates atrium from ventricles on each side

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17
Q

what are the semilunar valves

A

pulmonary valve goes from right ventricle to lung

aortic valve goes from left ventricle to body

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18
Q

where is the tricuspid valve found?

A

RA to RV

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19
Q

where is the pulomary valve found

A

RV to pulmonary trunk to lungs

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20
Q

where is the mitral/ bicuspid valve found?

A

LA to LV

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21
Q

where is the aortic valve found?

A

LV to aorta

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22
Q

what is the function of AV valves

A

allows blood to flow to ventricles ad prevents bacl flow during contraction

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23
Q

what are valves made of?

A

connective tissue connected to papillary muscles in endocardial wall
contraction of the muscles closes the valves

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24
Q

what are papillary muscles?

A

connected to valves and close and open them

they contract during systole and prevent valves inverting

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25
Q

what is S1

A

the sound of the closing of AV vales at start of ventricular systole

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26
Q

what is S2

A

the sound of semilunar valves closing at the edn of ventricular systole

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27
Q

whats key about looking at cardaic muscle

A

striations
collagen
intercolated disks

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28
Q

how does cardiac muscle appear ?

A

branches of the fibres and myocytes for branches

intercolates disks are seen between sections

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29
Q

whats the function of an intercolated disk?

A

form the mechanical connection for contraction and force to be transmitted across the heart

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30
Q

what cells are found in the heart?

A 
myocytes
ECM
fibroblasts
muscle
blood cells
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31
Q

what alters the distrubution of myocytes and fibroblasts?

A

species

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32
Q

what are the physical connections found in cardiac muscle?

A

intercollated disks

desmosomes

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33
Q

what do jap junctions do within cardiac muscle?

A

allow communication between adjacent cells

electrical, small molecules, small RNA

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34
Q

where are mitochondria found in cardiac muscle?

A

near the myofilament

35
Q

define sarcomere

A

small region of contraction

36
Q

thick filament

A

myosin

37
Q

thin filaments

A

actin

38
Q

dark bands

A

thick myosin mainly, some overlapping thin actin

39
Q

A bands

A

ansiotrophic bands, dark

thick myosin and some ovelapping actin

40
Q

light I bands

A

thin actin only

41
Q

whats the end of a sarcomere called?

A

Z line connects to ECM

42
Q

what is the M line?

A

middle of the sarcomere

myosin

43
Q

what happens during contraction

A

I band shrinks

A and M band shrink

44
Q

describe the steps of the sliding filament mechanism

A
  1. tropomyosin prevents myosin head attaching to binding sites of actin
  2. calcium ions released from endoplasmic reticulum causing tropomyosin to move
  3. myosin can now bind to actin
  4. head changes angle, moving actin along, ADP released. power stroke, conformational change
  5. ATP fixes to head, myosin detaches from actin
  6. ATP to ADP using ATPase makes energy for myosin head to resume normal
  7. cycle repeats
45
Q

what is actin and myosin like at rest?

A

proteins troponin and tropomyosin prevent myosin from interacting

46
Q

what does calcium do to tropomyosin?

A

causes a conformational change allowing actin and myosin to interact

47
Q

what is a T-Tubule?

A

helps transmit electrical signals into the interior of the cell
act as microvili increasing surface area

48
Q

7 steps of the cardiac cyce

A 
atrial contraction
isovolumetric contraction
rapid ejection
reduced ejection
isovolumetric relaxation
rapid filling
reduced filling
49
Q

what happens during atrial contraction

A

initiated by the P wave
valves between atria open
semilunar valves closed

50
Q

what is isovolumetric contraction

A

QRS complex
ventricle pressure increases with no volume change
contraction without volume change

no blood movement

51
Q

what happens during rapid ejection

A

blood flows rapidly from ventricles to arteries
AV closed
semilinar open

52
Q

what happens during isovolumetric relaxation?

A

valves closed
venticle pressure drops
no volume change but pressure drops

53
Q

was is reduced ejection?

A 
ventricles repolarise
tention in ventricle reduced
blood flow due to kinetic energy now
volume decreased
tension drops
54
Q

what is isovolumetric relaxation

A 
valves closed
ventricle pressure drops
pressure down after contraction
AV valve then open
no volume change but pressure down as muscle relaxes
55
Q

what is the ejection fraction?

A

proportion ejected out but some blood left behind

56
Q

what happens during rapid filling?

A

AV valves open, semilunar closed
ventricular relaxation
pressure lower in atria
fills with blood

57
Q

what happens during reduced filling?

A

chamber fills, pressure increases, amount of blood entering slows,
AV open so some blood flows via gravity to ventricles
semilunar closed

58
Q

which steps of the cardiac cycle are systole?

A

atrial contraction
isovolumetric contraction
rapid ejection
reduced ejection

59
Q

which steps of the cardiac cycle are diastole?

A

isovolumetric relaxation
rapid filling
reduced filling

60
Q

what is a diad?

A

The diad is a structure in the cardiac myocyte located at the sarcomere Z-line. It is composed of a single t-tubule paired with a terminal cisterna of the sarcoplasmic reticulum.

61
Q

function of the diad?

A

electrical impulse travesl through the diads to the cells

causes electrochemical gates to opn

62
Q

where does calcium come from for contraction?

A

first comes from outside the cell

this then triggers stores from the sarcoplasmic reticulum to be used

63
Q

by how much does the calcium concentration increases in the cytosol ready for contraction

A

from 0.1uM to 10uM

64
Q

how is calcium removed again after contraction?

A

calcium pump

sodium calcium exchanger

65
Q

what is excitation-contraction coupling?

A

physiological process of converting an electrical stimulus to a mechanical response. It is the link (transduction) between the action potential generated in the sarcolemma and the start of a muscle contraction

66
Q

what allows actin and myosin to bind/ interact?

A

the binding of calcium to trononin-C

67
Q

what does the binding of myosin to actin result in?

A

ATP hydroloysis which supplies the energy for the conformational change in actin-myosin

68
Q

how does calcium enter to cytosol?

A

L-type ca+2 channels

69
Q

what is calsequestrin?

A

calcium-binding protein of the sarcoplasmic reticulum. The protein helps hold calcium in the sarcoplasmic reticulum after a muscle contraction, even through the concentration of Ca is higher here than in the cytosol

70
Q

what does the sodium-calcium exchanger do?

A

exchanges 3 Na for each calcium
uses electrogenic potential generation to work
the calcium is moved out and Na in

71
Q

why is the Na/K pump also used in muscles?

A

during contraction, Na comes in but you dont want too much inside so the pump helps regulate this
by removing calcium, Na can get too high so it now triggers the Na/ pump to remove some Na

72
Q

name the pacemaker electrical acitivty cells in the heart

A

sino-atrial node
atrioventricular node
bundle of his
purkinje fibres

73
Q

how do electrical activty heart cells work?

A

they use ATP to create a concentration gradient of either side
the cell then works as a battery: then chennals are open there is a flow of ions ad a potential difference across the membrane and a flow of charge

74
Q

what are concentrations of K like?

A

high within the cell
low outside
chemical gradient for it to diffuse out of the cell

75
Q

what describes permeability of the cell embrane to a given ion?

A

conductance

76
Q

what is conductance

A

modification of currentX resistance = voltage

77
Q

when relaxed what is the potential difference of all the ions?

A

K higher inside
Ca higher inside
Na higher outside
pumps maintain this

78
Q

describe Ohms law

A

resistance is now conductance in this case

permeability of an ion is related to its charge

79
Q

what determines the movement of ions?

A

both the concentration gradient and membrane potential

and ion pumps

80
Q

what is the equilbrium for potassium

A

goes out

need negative potential

81
Q

whats the quilibrium for sodium

A

high cone outside
flows into cells
positive potential needed to stop flow in

82
Q

whats the equibrium for calcium

A

high outside
flows into cells
positive differene needed to repel it to move in

83
Q

what causes action potentials in non-pacemaker cells?

A

depolarising currents from neighbouring cells

84
Q

describe the generation of an acton potential

A
  1. STIMULUS excites the membrane, Na channels open Na in, less negative
  2. DEPOLARIsATION, reaches threshold, more Na influx
  3. REPOLARISATION, na channes close, K open, K diffuses out, back to resting negative
  4. HYPERPOLARIATION, K channels slow to close, more negative than resting
  5. RESTING ion channels reset

Human physiology (21 decks)

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