Brainscape's Knowledge GenomeTM

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


See full index

Cardiovascular System > Heart And Cell Activation > Flashcards

Heart And Cell Activation Flashcards

1
Q

What are cardiac myocytes

A

They are specialised cardiac cells

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

What are cardiac myocytes composed of

A

They are composed of bundles of myofibrils

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

How big is one cardiac myocyte

A

25u in diameter and 100u in length

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

What are the myofibrils composed of in cardiac cells

A

Myofillaments

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

What are myofibrils in cardiac myocytes

A

They are distinct repeating contractile units called sacromeres

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

What are sacromeres composed of

A

They are composed of thick and thin filaments

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

What are the thick and thin filaments composed of

A

Myosin and actin

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

What do the interaction between myosin and actin provide

A

Provide some evidence to support the sliding filament theory

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

What is myosin

A

Myosin is a protein which makes up the thickl filaments in sacromeres they have 2 heads which are able to interact with the binding sites on actin

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

When myocytes die what do they release

A

Troponin

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

What is the clinical relevance of cardiac myocytes dying

A

When they die they release troponin, high levels of troponin in the blood can aids the diagnosis of a Myocardial infarction

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

What do they chemical and physical interactions cause

A

They cause the length of the sacromeres to shorten

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

What are the thin filaments of actin composed of

A

They are composed of tropomyosin and troponin which is a regulatory protein complex

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

What is actin

A

Actin is a globular protein made of a chain of repeating units which makes up 2 strands which become an alpha helix

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

What is found between the 2 strands of alpha helix

A

In between is a rod shaped protein- tropomyosin

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

How many subunits of troponin are there

A

3

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

What are the 3 subunits of troponin

A

Troponin-T
Troponin-C
Troponin-I

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

What does troponin-T do

A

This attaches to tropomyosin

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

What does troponin-I do

A

This inhibits myosin binding

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

What does troponin-C do

A

This is the bonding site of Ca2+

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

When calcium binds to the troponin what happens

A

This binding causes a conformational change to the troponin complex where troponin-I moves away from the myosin binding site allowing myosin to bind

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

When calcium is removed from the troponin complex what is unable to bind

A

Myosin

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

When the myocyte is stretched what does this cause

A

This causes an increase of ventricular preload which increases the force of the contraction

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

What is the membrane of the heart permeable to

A

K+ Ions

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

What is the membrane of the hear muscle cell determined by

A

It is determined only by ions that can cross the membrane

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

Is the membrane of the heart muscle cell positive or negative

A

Negative

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

Why is the heart muscle cell membrane negative

A

Because k+ ions diffuse onwards from a high concentration to a low concentration so anions are unable to follow which causes a build up inside the cell and generates a negative potential within the cell

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

What is the Nernst equation

A

E= E0-RT/ZEinQ

E= reduction potential
E0=standard potential
R=universal gas constant
T=temperature in kelvin
Z= ion charge
F= faraday constant
Q=reaction quotient

29
Q

What goes in and out in the myocyte membrane pump

A

In= K+ ions
Out= Na+ and Ca2+

30
Q

What type of transport does the myocyte membrane pump use

A

Active transport with the use of ATP

31
Q

What does phase 0 show on the action potential graph

A

Rapid depolarisation due to Na+ ion inflow

32
Q

What does phase 1 show on the action potential graph

A

Partial repolarisation which is caused by K+ ions out and Na+ ion inflow stops

33
Q

What does phase 2 on the action potential graph show

A

A plateau, slow inflow of Ca2+ ions

34
Q

What does phase 3 show on the action potential graph

A

Repolarisation
K+ ions flow out of the cell
Ca2+ ions flow into the cell

35
Q

What does phase 4 show on the action potential graph

A

Pacemaker potential
Na+ ions in flow
Slow K+ ion outflow

36
Q

What type of drugs are quinidine and procainamide

A

They are class Ia and they are Na+ ion channel blockers which when taken cause a prolonged conduction repolarisation

37
Q

What type of drugs are lignocaine and what do they cause

A

They are class Ib drugs which are Na+ channel blockers which cause no effect to the conduction or repolarisation

38
Q

What type of drugs are flecainide

A

This is a class Ic drug which is am Na+ channel blocker which causes a prolonged conduction when taken

39
Q

What is a type of beta blocker

A

Sotalol

40
Q

What does the drug amiodarone causes when taken

A

This causes prolonged repolarisation due to it blocking the K+ channels

41
Q

How is action potential propagated

A

The action potential spreads over the cell membrane due to the positive charge from the Na+ ions affecting the adjacent cells which causes depolarisation via gap junctions

42
Q

Where is the conduction of electrical activity fastest

A

Purkinje fibres

43
Q

How fast is the electrical current in the purkinje fibres

A

4m/s

44
Q

What normally determines the rate of the heart beat

A

Sinoatrial node

45
Q

What is the resting membrane potential at the sinoatrial node

A

Resting membrane potential is around -55 to -60mV

46
Q

How does the resting membrane potential increase towards the threshold

A

Na+ channels close changing the potential of the membrane

47
Q

What does the atrioventricular node do

A

It transmits the cardiac impulse between the atria and ventricles, which causes a delay in impulse to allow for the atria to empty all the blood into the ventricles

48
Q

What are characteristics of the AV node

A

There are fewer gap junctions and have smaller fibres then in the atria

49
Q

What does rapid conduction of the signal cause in the HIS-purkinje system

A

Coordinated contraction of the ventricles

50
Q

What are characteristics of the HIS-purkinje system

A

They have large fibres and have high permeability at gap junctions

51
Q

What is a comparison of cardiac muscle and skeletal muscle

A

Cardiac muscle contraction lasts up to 15 times longer than that of a skeletal muscle due to the slow calcium channels which decrease permeability of membrane to the potassium after the action potential

52
Q

Why does the heart muscle have a refractory period

A

To further the stimulation of the action potential due to the fast Na+ +/- slow Ca2+ channels close which inactivates the gates

53
Q

What is the average refractory period for ventricles and what does it prevent

A

0.25s but is shorter for atria which prevents excessively frequent contractions

54
Q

What does a refractory period allow

A

This allows for adequate time for the heart to fill

55
Q

What is the relative refractory period

A

This happens after the absolute refractory period due to some of the Na+ channels are still closed and K+ channels still open so only strong stimuli can cause action potentials

56
Q

What does sympathetic control cause in relation to the heart

A

Increased heart rate which is positively chronotropic
Increased force of contraction is positively inotropic
Increased cardiac output

57
Q

When the sympathetic control increases the cardiac output how much is it increased by

A

Up to 200%

58
Q

What dose parasympathetic control cause in relation to the heart

A

Decrease in heart rate which is negatively chronotropic
Decrease in force of contraction negatively inotropic
Increase in cardiac output

59
Q

How much is the cardiac output decreased with parasympathetic stimulation

A

Up to 50%

60
Q

What is sympathetic stimulation controlled by

A

Adrenaline
noradrenaline
Type 1 beta adrenoreceptors

61
Q

Increased amount of adenyl cyclase in sympathetic stimulation causes

A

An increase of cAMP

62
Q

Decrease in sympathetic stimulation causes

A

Decrease in heart rate and force of contraction which causes a decrease in cardiac function by 30%

63
Q

What is parasympathetic stimulation controlled by

A

Acetylcholine and M2 receptors

64
Q

What does M2 receptors cause

A

An inhibits adenyl cyclase reducing cAMP

65
Q

Negative resting membrane potential is determined by

A

By Na+/K+ pump pumping out the K+ ions

66
Q

What is depolarisation caused by

A

Rapid influx of Na+ ions and prolonged influx of Ca2+ ions slowly

67
Q

What causes repolarisation

A

K+ ions exiting cells

68
Q

What causes propagation of action potential

A

Positive Na+ ions depolarising adjacent cells via the gap junctions

69
Q

What is excitation-contraction coupling

A

The contraction of the heart muscle requires the delivery of Ca2+ ions into the cytoplasm through surface ion channels which is then amplifies with NaCa

Cardiovascular System (12 decks)

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