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BRS > cardiovascular- control of heart function > Flashcards

cardiovascular- control of heart function Flashcards

1
Q

What are 3 components of heart?

A
  1. muscle cells : contract + relax 2. specialised electrical cells: create currents and trasnmit those in. regulate contraction 3. vessels: coronary blood vessels supply heart
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2
Q

What is the pacemaker?

where it is found.

A

sinoatrial node. at the junction of crista terminalis

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3
Q

What else has pacemaker activity?

A

Atrioventricular node, slowc alcium mediated AP

found in triangle of koch at base of right atrium

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4
Q

What do internodal tracts do?

A

connect sinoatrial node to AV node

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5
Q

What does bundle of His do?

A

from atrium through intraventricular septum to apex of heart to supply purkinje fiberes

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6
Q

How many phases does AP of a nodal cell have?

what are they called?

A
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7
Q

What is each phase of nodal cell AP due to?

A

upstroke - due to Ca2+ influx

repolarisation- due to k+ efflux

pre-portiential - NO resting membrane due to Na+ influx through funny channel

(happens straight after repolar always increasing to upstroke)

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8
Q

What is important to consider about Ap profiles of cardio cells?

and how is it caused?

A

different AP shapes

different ions flowing and different ion channels expression on CM

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9
Q

compare a cardiac muscle and nerve muscle

A

longer AP in cardiac as controls contraction of heart,, to produce an effctive pump

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10
Q

Stages of AP in cardiac muscle? (5)

A
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11
Q

What else is there outside of 5 phases in Ap of cardiac muscle?

A

Absolute refractory period

relative refractory period

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12
Q

What is aboslute refractory period?

A

time during which no AP can be intiated regardless of stimulus intesnity

so heart doesn’t many beats in small amount of time

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13
Q

What is relative refractory period?

A

period after ARP when AP can only be elicted when larger stimulus strength

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14
Q

What is each phase of ventricular cell due to?

A

0 - K+ efflux

1 - Na+ in

2 - Ca2+ in

3&4- K+ out

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15
Q

What 3 organ systems have an effect on activity of heart?

A
  1. brain/CNS - immediate change through nerve activity or slower hormonal
  2. kidney - bidirectional through indirect mechanisms
  3. blood vessels influence amount of blood in an out
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16
Q

How does parasymathetic travel to heart?

and effect?

A

vagus nerve

decrease HR by decrease AP in nodal cell, SAN

decreased slop of phase 4

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17
Q

What affect does sympatheric on heart?

A
  1. incraese HR by - increase slope of phase 4, easier AP
  2. increase contraction - increase Ca2+ dyanmics
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18
Q

What does pre-ganglion nerves of parasym use as NT?

A

aceetylchiline

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19
Q

What does post-ganglion nerves of parasym use as NT?

A

Ach

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20
Q

What are the 2 receptors of parasym pathway?

A
21
Q

What do pre-gang nerves of symypathetic use as NTs?

A

Ach

22
Q

What do post-gang nerves of symypathetic use as NTs?

A

Noradrenaline

23
Q

where do SNS pre and post gang synapse?

A

sympatheric chain

(paraverterbral ganglia)

24
Q

Where is vasomotor centre located?

A

medulla and lower 1/3 of pons

25
Q

What is it VMC compsoed of?

A

vasocontrsictor area

vasodilator area

cardio-reg inhibitory area

26
Q

Where do its impluses go?

A

almost all blood vessels

27
Q

What has effects of VMC?

A

higher centres of brains such as hypothalamus exert excitary or inhibitory effects

28
Q

What does lateral portions of VMC control?

A

Heart activiy by influecning heart rate and contractibility

29
Q

What is the function of medial portion of GMC?

A

transmits via vagus nerve to heart, decreae HR

30
Q

What receptors are on heart?

A

parasympathetic SA nodule - M2 muscorinic receptor

sympathetic noradrenaline on B1 receptors

31
Q

What effect does CUTTING sympathetic and parasymp have on heart?

A

decrease heart rate even when being directly stimulted

they always have an effect even when not being inervated

i.e basal effect

32
Q

How do symp effect kidneys?

A

deccrease glomerular filtration - decrease Na+ sectrion

increase blood volume

33
Q

How is blood volume detected?

A

venous volume receptors

34
Q

What affect does increase in sympathetic nerves have on kidney?

A

increase activity

increase renin

increase AT11: causes vasoconstriction and increase BP

35
Q

What is blood pressure detected by?

A

aterial baroreceptos

36
Q

How does kidney indirectly affect heart?

A

control of blood volume and pressure that in turn is detected and effects heart function

37
Q

Exactly how does sympathetic effect renal system?

A

2 areas-

afferent arterioles of glomerulus

by activation fo a1-adrenoceptors - vasonctiction that causes decrease GFR as decreased Na+ increases BV

other affect is on juxgolumerus cells - renin secretion by B1 adreonergic receptor increases BP

38
Q

How is blood volume increased by sympathetic nerves in kidneys?

A

juxtaglomerular cells

B1-adrenoceptor causes renin secretion

increases aldosterone

39
Q

What are uses/sensation of volume?

A

in importantly large pulomonary vessels, atria, ventricle

signals thro glossopharyngeal and vagus nerve,

decreased filling increases firing and SNS activity

40
Q

What is distention?

What effect does it have on nervous pathway?

A

distention - heart full

increase baroreceptor and decreases SNS

41
Q

What regulates blood volume filling?

A

kidney and blood vessels

42
Q

Where are PRESSURE sensors found in blood vessels to feedback for heart?

A

arterial circuit: aortic arch, cartoid sinus and afferent aterioles of kidney

43
Q

What effect does decrease in pressure have on pressure sensors in arterial arch?

A

less baroreceptor firing and increased SNS activity

44
Q

What affects venous volume?

A

venous tone, gravity, skeletal muscle pump and breathing

45
Q

central venous pressure determines what?

A

amount of blood flowing back to heart

46
Q

What effect does constricition have on veins?

A

constriction reduces compiance and increaes venous return

47
Q

In aterioles what constricition determine?

A

a) blood flow to downstream organs
b) mean arterial blood pressure
c) pattern of blood flow to organs

48
Q

What effects venous pressure and what effect does venous pressure have?

A
49
Q
A

BRS (19 decks)

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