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block 2 Anna > block 2 lecture 10 > Flashcards

block 2 lecture 10 Flashcards

1
Q

what is the appearance of cardiac muscle?

A

striated, branched with intercolated discs

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2
Q

what ensures the muscle acts as one functional unit?

A

wave of depolarisation moves via gap junction

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3
Q

what are myocytes made up of?

A

myofibrils

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4
Q

myosin structure?

A 
tail region of alpha chains in an alpha helix
hinge region
2 heads
regulatory light chians 
alkyle light chains
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5
Q

what allows myosin heads to bind to the actin?

A

hydrolysis of ATP

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6
Q

what type of protein is actin?

A

globular

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7
Q

what is the structure of actin?

A

two helical stands

inbetween strands is tropomyosin

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8
Q

what is the troponin complex?

A

troponin I
troponin C
troponin T

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9
Q

what is troponin I?

A

the inhibitory part

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10
Q

what does troponin C do?

A

binds to calcium ions

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11
Q

what does troponin T do?

A

keeps the troponin bound to the actin

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12
Q

what happens to troponin when calcium binds?

A

confirmational change and cross bridges can form

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13
Q

what happens to the products of ATP hydrolysis when it binds to myosin?

A

stays bound

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14
Q

what produces the power stroke?

A

inorganic phosphate is released

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15
Q

what is excitatory contraction coupling?

A

an action potential triggers a myocyte to contract

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16
Q

what happens when an action potential depolarises the membrane of a myocyte?

A

calcium ion channels open allowing influx of calcium ions

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17
Q

what are dihydropyridine receptors?

A

voltage gated calcium ion channels in the T tubules

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18
Q

what are ryonidine receptors?

A

receptor on the sarcosplasmic reticulum

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19
Q

what is the calcium release process called in the muscle of the heart?

A

calcium induced calcium influx

20
Q

what controls the rate and force of contraction?

A

autonomic nervous system

21
Q

what is released in the sympathetic system and where is it released from?

A

noradrenaline from the accelerator nerve

adrenal glands secrete adrenaline

22
Q

what happens when the neurotransmitter of the sympathetic nervous system binds to the calcium receptors?

A

triggers calcium ion channels to trigger an influx of calcium ions which induces calcium release from the sarcoplastic reticulum

23
Q

what can the noradrenaline bind to?

A

beta 1

24
Q

what happens when noradrenaline binds to beta 1?

A

activates adenylate cyclase, forms cAMP, protein kinase phosphorylated, phospholamban phosphorylated so sarcoplasmic reticulum can pump calcium in

25
Q

what is lusitropy?

A

relaxation

26
Q

how does lusitropy work?

A

sarcoendoplasmic reticulum calcium ATPase returns calcium into the sarcoplasmic reticulum,
sodium/calcium exchanges in the sarcolemma transports calcium out of the cell

27
Q

where are the cardiac inhibitory and cardiac accelerator centers?

A

medulla

28
Q

what does the sympathetic nerve innervate?

A

nodes and ventricular muscle

29
Q

what does the SAN release and where does it go?

A

acetylecholine onto the muscarinic receptors

30
Q

what affects does noradrenaline have?

A

positive chronotropy
positive dromotropy
positive inotropy

31
Q

what is positive chronotropy?

A

increase heart rate

32
Q

what is positive dromotropy?

A

increased conduction velocity

33
Q

what is positive inotropy?

A

increased contractility

34
Q

what does acetylecholine bind to?

A

M2 receptors

35
Q

what does acetylecholine binding to M2 receptors do?

A

negative chronotropy, dromotropy and inotropy

36
Q

what happens when noradrenaline is released from the SAN?

A

bind to beta 1 coupled to G stimulatory proteins, CAMP is formed and protein kinase A is activated, calcium ion channel is depolarised, this increases action potential generation resulting in increased chronotropy and inotropy

37
Q

what happens exactly when acetylecholine is released from SAN?

A

binds to muscarinic M2 inhibiting G proteins meaning you get phosphorylation of a potassium ion channel (GIRK) this causes potassium ions to leave the cell, this hyperpolarises the cell and decreases the heart rate

38
Q

phase 4? sino atrial node action potential

A

sodium influx, calcium ion channels recover from inactivation, pump restores the ion gradient

39
Q

phase 0? sino atrial node action potential

A

calcium ions influx this depolarised the SAN cells

40
Q

phase 3? sino atrial node action potential

A

calcium ion channels become inactivated and there is a delayed potassium ion efflux to restore resting potential.

41
Q

important feature of atrial emptying?

A

mostly passive

42
Q

route of electrical activity in the heart?

A

sino atrial node
bundle of hiss
purkinje fibers

43
Q

what is the anulus fibrosus?

A

acts as an electrical insulator between the atria and ventricles

44
Q

what is the pacemaker of the heart?

A

SAN

45
Q

what is EDV?

A

end diastolic volume

volume of blood left at the end of diastole

46
Q

what is isovolumetric contraction?

A

when volume of blood remains the same but the pressure is increasing due to contraction

block 2 Anna (10 decks)

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