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Cardiorespiratory Biology > Cardiac Output 1 > Flashcards

Cardiac Output 1 Flashcards

1
Q

cardiac output

A

the volume of blood ejected from a ventricle per minute (L/m)

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2
Q

what is the cardiac output a product of and is therefore controlled by?

A

stroke volume and heart rate

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3
Q

typical stroke volume

A

~70ml

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4
Q

typical heart rate

A

~70

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5
Q

typical cardiac output

A

~5L/m

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6
Q

what regulates the cardiac output

A

autonomic nervous system - sympathetic
parasympathetic
barosympathetic

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7
Q

what intrinsically regulates the cardiomyocytes

A

frank starling law of the heart

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8
Q

name 4 things ANS controls

A 
blood pressure
temperature 
digestion
reproductive function 
(all regarding homeostasis)
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9
Q

what segments of the spinal chord does the Sympathetic Nervous System contain

A

thoraco-lumbar

Segments T1-L2

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10
Q

what segments of the spinal chord does the Parasympathetic Nervous System contain

A

cranio-sacral

cranial nerves III, VII, IX, X sacral segments 2,3,4

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11
Q

SNS primarily acts via…

A

catecholamines

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12
Q

how does the SNS change cardiac output

A

increase heart rate
stroke volume
increase blood pressure

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13
Q

what hormones are released from SNS and where

A

noradrenaline - from nerve endings
adrenaline - from adrenal gland
sweating/pilorecetion but ACh

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14
Q

SNS action is mediated by …

A

the α- and β-adrenoceptors

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15
Q

the most important adrenoreceptor for the heart is

A

β1 -adrenoceptor

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16
Q

what particular adrenoreceptors play a role in heart

A

a1

B2

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17
Q

where are the adrenoreceptors B1, B2, a1 in the heart

A

SA node
AV node
atria and ventricle

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18
Q

what type of receptor is B-adrenoreceptor and what is it linked to.
This leads to the increase of what

A

G protein couple receptors adenylate cyclase

increase of cAMP which in turn activates protein kinase A (PKA)

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19
Q

Depolarising current in SA node comes from what channel

A

Na+/K+

HCN channels

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20
Q

HCN

A

hyperpolarisation-activated, cyclic nucleotide-gated

– current through this is increased by the binding of cAMP

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21
Q

Adrenergic Action of the Heart

A

• The β-adrenoceptor is a G-protein couple receptor linked to adenylate cyclase
– increases cAMP which in turn activates protein kinase A (PKA)
• The main depolarising current in the SA node comes from the Na+/K+ HCN
– current through this is increased by the binding of cAMP
• In the myocytes (atria and ventricles) cAMP/PKA increases the entry of Ca2+ into cells
– this increases the force of contraction

22
Q

Cardiac contraction

A

Ca2+ binds to troponin on actin
allows myosin to interact
Ca2+ comes from outside of cardiomyocytes

23
Q

categories of acetylcholine

A

muscarinic and nicotinic cholinergic receptors

24
Q

PNS acts via

A

acetylcholine

25
where are nicotonic cholinergic receptors found
– nicotinic are ion channels found in nerves and skeletal muscle
26
muscarinic cholinergic receptors are found
G - protein coupled receptors
27
how is PNS innervated to the heart
via the vagus nerve | – cranial nerve X (CNX)
28
maine cholinergic receptor in the heart
M2
29
What does the vagus cranial nerve innervate
SA node AV node parts of the atria
30
function of M2 receptor
r inhibits adenylate cyclase | – and so the amount of cAMP
31
how does the M2 receptor inhibiting adenylate cyclase affect the SA node
, this decreases the Na+ influx and so the rate of depolarisation – it decreases the rate of SA node firing and so heart rate has small effect on force atrial contraction but none on ventricle
32
tachycardia is a sign of
sympathetic activation | caused by exercise, anxiety
33
how do Beta blockers change cardiac output
drop heart rate from 70 to 60bpm
34
what is the intrinsic rate of SA node but what gives the heart its normal 70bpm
The intrinsic rate of the SA node is about 100 bpm, it is vagal stimulation that gives the “normal” 70 bpm
35
cardiac output is intrinsically tied to ...
blood pressure | more blood in system -> higher pressure
36
how to calculate mean arterial pressure
cardiac output x total peripheral resistance
37
control of blood pressure is managed by
regulating cardiac output via the autonomic nervous system
38
what type of loop is baroreceptor reflex
negative feedback loop | sensory afferents -> central processing- > effector efferents
39
what do sensory fibres detect and where are they located
detect stretch located in aortic arch carotid sinus firing is proportional to stretch
40
where do the signals from the sensory fibres in the aortic arch and carotid sinus go to?
brain stem | – the nucleus tractus solitarius (NTS) of the medulla oblongata
41
what does the medulla regulate
SNS/PNS outflow of the heart drop in pressure - increase SNS and cardiac output rise in pressure - increase PNS and decrease cardiac output
42
exercise is related to what Nervous System
increase SNS activity
43
cardiac out put changes in exercise
increase heartrate | increase cardiac output
44
how does the systolic pressure change
drastic increase
45
how does the mean arterial pressure change
slight increase
46
how does the diastolic pressure change
slight decrease
47
how does the cardiac output change
drastic increase
48
how does the peripheral resistance change
drastic decrease
49
why can't heart rate increase above 200 bpm
length of action potential | high rates = decreased perfusion as it occurs in diastole
49
why can't heart rate increase above 200 bpm
length of action potential | high rates = decreased perfusion as it occurs in diastole

Cardiorespiratory Biology (25 decks)

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