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cardiovascular- control of heart function Flashcards

(49 cards)

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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?

21
Q

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

22
Q

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

Study These Flashcards
A

Noradrenaline

23
Q

where do SNS pre and post gang synapse?

Study These Flashcards
A

sympatheric chain

(paraverterbral ganglia)

24
Q

Where is vasomotor centre located?

Study These Flashcards
A

medulla and lower 1/3 of pons

25
What is it VMC compsoed of?
vasocontrsictor area vasodilator area cardio-reg inhibitory area
26
Where do its impluses go?
almost all blood vessels
27
What has effects of VMC?
higher centres of brains such as hypothalamus exert excitary or inhibitory effects
28
What does lateral portions of VMC control?
Heart activiy by influecning heart rate and contractibility
29
What is the function of medial portion of GMC?
transmits via vagus nerve to heart, decreae HR
30
What receptors are on heart?
**parasympathetic** SA nodule - M2 muscorinic receptor **sympathetic** noradrenaline on B1 receptors
31
What effect does CUTTING sympathetic and parasymp have on heart?
decrease heart rate even when being directly stimulted they always have an effect even when not being inervated i.e basal effect
32
How do symp effect kidneys?
deccrease glomerular filtration - decrease Na+ sectrion increase blood volume
33
How is blood volume detected?
venous volume receptors
34
What affect does increase in sympathetic nerves have on kidney?
increase activity increase renin increase AT11: causes vasoconstriction and increase BP
35
What is blood pressure detected by?
aterial baroreceptos
36
How does kidney indirectly affect heart?
control of blood volume and pressure that in turn is detected and effects heart function
37
Exactly how does sympathetic effect renal system?
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
How is blood volume increased by sympathetic nerves in kidneys?
juxtaglomerular cells B1-adrenoceptor causes renin secretion increases aldosterone
39
What are uses/sensation of volume?
**in importantly large pulomonary vessels**, atria, ventricle signals thro glossopharyngeal and vagus nerve, decreased filling increases firing and SNS activity
40
What is distention? What effect does it have on nervous pathway?
distention - heart full increase baroreceptor and decreases SNS
41
What regulates blood volume filling?
kidney and blood vessels
42
Where are PRESSURE sensors found in blood vessels to feedback for heart?
arterial circuit: aortic arch, cartoid sinus and afferent aterioles of kidney
43
What effect does decrease in pressure have on pressure sensors in arterial arch?
less baroreceptor firing and increased SNS activity
44
What affects venous volume?
venous tone, gravity, skeletal muscle pump and breathing
45
central venous pressure determines what?
amount of blood flowing back to heart
46
What effect does constricition have on veins?
constriction reduces compiance and increaes venous return
47
In aterioles what constricition determine?
a) blood flow to downstream organs b) mean arterial blood pressure c) pattern of blood flow to organs
48
What effects venous pressure and what effect does venous pressure have?
49

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