Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

bioregulatory systems 🦠 > control of heart function > Flashcards

control of heart function Flashcards

1
Q

what cells can contract and relax in response to electrical stimuli

A 
muscle cells (cardiac myocytes)
essential for pumping blood around the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what do specialised electrical cells do

A

they are cells that create spontaneous currents and those that transmit currents exist within the heart - essential for regulation contraction of cardiac myocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the vessels responsible for

A

the major blood vessels are responsible for transporting the blood in and out of the heart
while the coronary blood vessels are responsible for supplying blood to the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what cells are the most prominent in controlling heart function

A

electrical cells

although cardiac myocytes and vessels of the heart are able to modulate function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 2 nodes of the heart

A

SAN

AVN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the SAN and where is it found

A

pacemaker of the heart - 60-100 bpm

at the junction of crista terminalis - upper wall of right atrium and opening of superior vena cava

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the AVN and where is it found

A

has pacemaker activity : slow calcium mediated action potential
traingle of Koch at the base of right atrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the bundle of His and bundle branches

A

internodal tracts - specialised myocytes
connect the SAN to AVN
bundle of His that goes from the atria down through interventricular septum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are purkinje fibres

A

specialised conducting fibres along ventricles of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how many phases does nodal action potential have

A

3 phases (0, 3 and 4)
in the order 4 0 3
(pre potential, upstroke and then repolarisation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is upstroke and what is it due to

A

depolarisation due to Ca2+ influx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is repolarisation due to (in terms of ions)

A

K+ efflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

do nodal cells have a resting membrane potential

A

no

only a pre potential due to Na+ influx through a “funny” channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

why do different parts of the heart have different action potential shapes

A

caused by different ion currents flowing and different ion channel expression in cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

which AP is longer - cardiac or nerve

A

cardiac AP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does the duration of AP control the duration of

A

contraction of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what kind of contraction is required to produce an effective pump

A

long slow contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how many phases does AP have

A

5 phases labelled 0-4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe phase 0

A

upstroke

start off with resting membrane potential around -80/90 mV then upstroke takes it up to 20/30 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

describe phase 1

A

early repolarisation

brings the membrane potential back down to a slightly more negative value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

describe phase 2

A

plateau

maintains the cell at a level of depolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

describe phase 3

A

repolarisation

repolarisation at around 270 ms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

describe phase 4

A

resting membrane potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the absolute refractory period (ARP)

A

time during which no AP can be initiated regardless of stimulus intensity
(phases 0, 1 and 2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the relative refractory period (RRP)

A

period after ARP where an AP can be elicited but only with larger stimulus strength
(phases 3 and 4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what are 3 major organ systems that have the ability to modulate the activity of the heart

A

the brain/CNS
the kidneys
the blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how can the brain/CNS modulate heart activity

A

can effect immediate changes through nerve activity or slower changes through hormonal activity
the CNS also impacts other systems > subsequently affecting the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

how can the kidneys modulate heart activity

A

the heart and kidneys share a bidirectional regulatory relationship usually through indirect mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

how can the blood vessels modulate heart activity

A

by regulating the amount of blood that goes to and from the heart, the blood vessels are able to influence cardiac activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

how is the autonomic nervous system involved in CNS control of the heart

A

cairo-regulatory centre and vasomotor centres in medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

how is the parasympathetic nervous system involved in CNS control of the heart

A

rest and digest
PS nerves leave from medulla and goes via vagus nerve to heart
PS nerve is activated > causes a decrease in HR
decreases slope of phase 4 reducing HR by affecting SAN
affects pre-potential of AP within nodal cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

how is the sympathetic nervous system involved in CNS control of the heart

A

fight or flight
increase in HR (positive chronotrophy) - increases the slope of phase 4 (sympathetic nerves decreases time taken to get back to depolarisation phase)
increase force of contraction (inotropy) - increases Ca2+ dynamics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what does an increase in volume and pressure activate

A

baroreceptors

reduce SNS activity and HR

34
Q

design of the ANS

A

split into PNS and SNS

35
Q

describe the parasympathetic nervous system

A

parasympathetic nerves arising from cranial part of spinal cord and sacral part of spinal cord
rest and digest
preganglionic fibres (long) use ACh as NT
PNS post ganglionic NT = ACh
PNS is important for controlling the HR

36
Q

describe the sympathetic nervous system

A

arises from thoracic vertebrae and lumbar vertebrae
fight or flight
preganglionic fibres (short) use ACh as their NT
SNS post ganglionic NT = NA (noradrenaline)
SNS is important for controlling the circulation

37
Q

where is the vasomotor complex located

A

located bilaterally in reticular substance of medulla and lower third of pons

38
Q

what is the vasomotor cortex composed of

A

vasoconstrictor (pressor) area
vasodilator (depressor) area
cardioregulatory inhibitory area

39
Q

where are impulses transmitted through

A

distally through spinal cord to almost all blood vessels

40
Q

what can exert powerful excitatory or inhibitory effects on the vasomotor complex/centre

A

many higher centres of the brain such as the hypothalamus

41
Q

what do lateral portions of Vasomotor complex/centre control

A

heart activity by influencing heart rate and contractility

42
Q

what do medial portions of the vasomotor complex/centre transmit

A

signals via the vagus nerve to the heart that tend to decrease heart rate

43
Q

what does the PS release to inhibit the SAN

A

releases ACh
acts on M2 muscarinic receptors on cell membrane of SAN cell and by a G protein known as Gi protein > inhibition of adenylyl cyclase > prevents conversion of ATP to protein kinases

44
Q

what does the sympathetic system release to activate/stimulate the SAN

A

releases noradrenaline > acts on beta 1 receptors > stimulates adenylyl cyclase and cause increase in level of protein kinase A

45
Q

what is shown if you cut sympathetic nerves

A

the heart rate goes down suggesting that there was already some level of S activity occurring all the time

46
Q

describe how sympathetic nerves in the renal system regulate blood volume and can therefore affect BP

A

sympathetic nerves innervate the kidneys

they reduce glomerular filtration (less filtered) > decreases Na+ excretion > increasing blood volume (aldosterone)

47
Q

what is blood volume detected by

A

venous volume receptors

48
Q

sympathetic nerves can also increase activity

how do the kidneys regulate blood volume and pressure with increased renin secretion?

A

increased renin secretion > releases angiotensin 2 (causes release of aldosterone - impacts blood volume/increased production of aldosterone leads to vasoconstriction and increases blood pressure)

49
Q

what cells is blood pressure detected by

A

arterial baroreceptors

decreases SNS activity and decreases HR

50
Q

what nerve fibres innervate afferent and efferent arterioles of the glomerulus and nephron tubule cells

A

sympathetic nerve fibres

51
Q

where is the primary site of sympathetic activity

A

afferent arterioles

52
Q

STEPS for what happens at afferent arterioles upon release of NA

A

release of NA

1) activation of alpha 1 adrenoreceptor
2) reduced chronotropy and increased intropy for heart
3) activation of receptors causes vasoconstriction (reduces GFR and increases blood volume)
4) reduction in GFR = reduction in Na+ filtered
5) sympathetic nerves act on juxtaglomerular cells (site of synthesis, storage and release of renin)
6) stimulation of beta 1 adrenoreceptor leads to renin secretion
7) renin increases blood volume by sympathetic nerves at the kidney

53
Q

what do volume sensors do

A

also atria and right ventricle

send signals through glossopharyngeal and vagus nerves

54
Q

what does a decrease in filling (less blood returning to the heart) lead to

A

reduction in baroreceptor firing > increased SNS activity

increased HR

55
Q

what does distension (heart is full - more blood returning to the heart) lead to

A

increased baroreceptor firing

decreased SNS activity

56
Q

what regulates how much blood coming back to the heart

A

kidneys and blood vessels

57
Q

what is involved in the arterial circuit

A

aortic arch
carotid sinus
afferent arterioles of the kidneys

58
Q

what do pressure receptors do

A

send signals through glossopharyngeal and vagus nerves

59
Q

what does a decrease in pressure lead to

A

reduction in baroreceptor firing

increases SNS activity

60
Q

what does an increase in pressure lead to

A

increased baroreceptor firing

decreased SNS activity

61
Q

what is the relationship between baroreceptor firing and SNS activity

A

they are reciprocals

62
Q

how many circulations are there and what are their names

A

2 circulations
pulmonary and systemic
right heart > lungs > left heart > body

63
Q

what is venous volume and what is venous volume distribution affected by

A

venous volume = amount of volume in veins

affected by peripheral venous tone, gravity, skeletal muscle pump and breathing

64
Q

what is central venous pressure and what does it determine

A

mean pressure in right atrium
determines the amount of blood flowing back to the heart
determines filling pressure and distension of the heart

65
Q

what determines stroke volume

A

the amount of blood flowing back to the heart (Starling’s Law of the heart)

66
Q

in veins, what does constriction do

A

constriction reduces compliance and increases venous return - greater pressure (bigger effect than decreased volume due to constriction)

67
Q

in arterioles (less blood but higher pressure) constriction determines? (3)

A

blood flow to downstream organs
mean arterial blood pressure
the pattern of blood flow to organs

68
Q

what are local mechanisms for regulating blood flow (characteristics not actual things)

A

intrinsic to smooth muscle (or closely associated)

important for reflex local blood flow regulation within an organ

69
Q

what are some endothelium derived vasodilators

A

Nitric oxide

prostacyclin

70
Q

what are some endothelium derived vasoconstrictors

A

thromboxane A2

endothelins

71
Q

what does NO do

A

potent vasodilator

diffuses into vascular smooth muscle cells

72
Q

what does prostacyclin do

A

vasodilator

has antiplatelet and anticoagulant effects

73
Q

what does thromboxane A2 do

A

aka TXA2

vasoconstrictor that is also heavily synthesised in platelets

74
Q

what do endothelins do

A

ET

vasoconstrictors generated from nucleus of endothelial cells

75
Q

what are characteristics of systemic mechanisms

A

extrinsic to smooth muscle

these include the autonomic nervous system and circulating hormones

76
Q

what are some non endothelium derived vasodilators

A

kinins

atrial natriuretic peptide (ANP)

77
Q

what are some non endothelium derived vasoconstrictors

A

vasopressin
noradrenaline/adrenaline
angiotensin 2

78
Q

what do kinins do

A

vasodilator

binds to receptors on endothelial cells and stimulates NO synthesis

79
Q

what does atrial natriuretic peptide (ANP)

A

vasodilator

secreted from the atria in response to stretch to reduce BP

80
Q

what does vasopressin do (ADH)

A

vasoconstriction
secreted from the pituitary gland
binds to V1 receptors on smooth muscles to cause vasoconstriction

81
Q

what does noradrenaline/adrenaline do

A

vasoconstriction

secreted from the adrenal glands (and SNS) causing vasoconstriction

82
Q

what does angiotensin 2 do

A

potent vasoconstrictor from the renin-angiotensin-aldosterone axis
also stimulates ADH secretion

bioregulatory systems 🦠 (54 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions