Brainscape's Knowledge GenomeTM

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


See full index

Integrative Physiology > Week 2: Cardiac function > Flashcards

Week 2: Cardiac function Flashcards

1
Q

What are the 2 main cardiac cells? What are their main function?

A
  • Autorythmic: Generate heart beat
  • Myocardial: Mechanical Pumping
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the main components of cardiac myocytes? and breifly what do each of the components do?

A

Intercalated discs: Tightly connect cardiac myocytes together and keep them all in sync.

Desmosomes: Intercellular junctions that provide strong adhesion between cells

Gap Junctions: allow for depolarizing current to move quickly from cell to cell

Many Mitochondria: Required for high ammount of activity

Large T-Tubules: Allows for more Ca2+ from ECF to move into the cell.

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

What is the “drift” event of the AR cells due to?

A
  1. Cyclical decrease in normal passive K+ efflux from cells
  2. Special voltage-gated Na2+ channels (If Channels) open when the membrane becomes hyperpolarised resulting in Na2+ influx and continued K+ Efflux.
  3. Ca2+ moves through transient Ca2+ Channels (T-Type) which takes the membrane to threshold.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does the autonomic Nervous system effect AR cells?

A

SympNS: Speeds heart rate by increase calcium influx and If channel flow.

ParasympNS: Slows heart rate by Increasing pottasium Efflux and decreasing calcium influx

This is all controlled by type of neurotransmitter that is released.

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

Why is the SA node the pacemaker of the heart?

A

Because it depolerizes the fastest.

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

How does the electrical signal travel through the heart? what is the pathway?

A
  1. AP originates from AR cells in SA node
  2. Spreads via gap junctions down internodal pathways across atrial myocardial cells = Biggining atrial contraction
  3. There is now an AV node delay (Pause)
  4. The signal then continues through from the AV node to the bundle of his -> bundle branches -> purkinje fibres
  5. As the signals transfer down through the ventricular walls, ventricular contraction will begin from the apex of the heart.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why do we have an AV nodal delay?

A

this 0.1 second delay allows for completion of atrial contraction = squeezing remaining blood into ventrical.

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

Explain what happens during the excitation of contractile cardiac cells?

A
  1. AP is brought about by a sudden increase in membrane permeability to Na+ .
  2. Na+ Permeability then falls to a lower resting level
  3. The membrane decreases permeability to potassium and increases permeability to calcium causing a maintained depolerisation phase that lasts around 700 milliseconds.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain what is happening during steps 0-4? what charges are present at each step?

A
  1. Sodium channels open
  2. Sodium channels close (+20mv to +30mv)
  3. Slow calcium channels open and fast K+ channels close
  4. Calcium channels close and slow K+ channels open
  5. Return to resting membrane potential (-90mv)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

why do we need a refractory period in contractile cardiac muscle but not skeletal muscle?

A

Contractile cardiac muscle acts as a pump for the heart and unlike skeletal muscle cannot go into tetatus. The reason for this is because the ‘pump” has to fill. The refractory period is the period that the heart refils itself (relaxing) and gets ready to pump blood back around the body (contraction).

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

Are T-Tubules larger in Skeletal muscle cells or Myocardial cells? explain?

A
  • T-Tubules of myocardial cells are larger than those in skeletal muscle cells and they branch inside of the cell
  • Due to cardiac muscle having a relatively less sarcoplasmic reticulum within the cell, it relies on the larger T-Tubules to get Ca2+ from the ECF into the cell.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is happening in stages 1 through to 10?

A
  1. AP enters from adjacent cell
  2. Voltage gated Ca2+ channels open = Ca2+ enters cell
  3. Ca2+ induces Ca2+ release (CICR) through Ryanodine receptor-channels (RyR)
  4. Local release causes Ca2+ spark
  5. Ca2+ sparks create a Ca2+ signal
  6. Ca2+ ions bind to troponin to initiate contraction (Actin and Myosin complex)
  7. Relaxation occurs when Ca2+ unbinds from troponin
  8. Ca2+ is pumped back into the sarcoplasmic reticulum for storage.
  9. Ca2+ is exchanged with Na+ by the NCX antiporter
  10. Na+ gradient is maintained by the Na+-K+-ATPase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is the plateau phase established?

A

The extra Ca2+ from the ECF is largely responsible.

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

What is the effect of phospholamban on Ca2+-ATPase activity when stimulated by Catecholamines (adrenalin)?

A

When phospholamaban is stimulated by adrenanlin it enhances Ca2+-ATPase activity on the SR membrane resulting in an increase to storage of Ca2+ so that when an AP comes, there will be a stronger contraction because of the greater ammount of Ca2+ that was stored.

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

What is an ECG?

A

A graphic recording of the hearts electrical activity. It indirectly measures the depolerisation and repolarisation of heart muscle cells.

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

Fill in what is happening between A-E and 1-5?

A

A. Atrial Depolarization 1. P-Wave

B. Delay at AV node 2. P-R or P-Q segment

C. Ventricular Depolarization 3. QRS complex

D. Ventricular Repolarization 4. T-Wave

E. No Electrical Activity (Ventricles are relaxing and filling 5. Isoelectric line (TP Interval)

17
Q

How do leads aVR, a VL, and aVF view the heart?

A

aVR = From right shoulder

aVL = From left shoulder

aVF = Directly upward from feet

18
Q

What is happening in events 1 to 8 in relation to the Electrical events of the cardiac cycle?

A
  1. P-Wave (atrial Depolarization)
  2. PQ or PR segment: Atria contract

3, 4, and 5. Ventricular depolarization and atrial repolazing simultaneously

  1. ST segment: Ventricles contract
  2. T-Wave: Ventricular Repolarization
  3. End: Ventricular Filling
19
Q

In detail, What is happening during Ventricular systole?

A
  • The wave of depolarization passes through the ventricular muscle mass and causes ventricular contraction.
  • The ventricular pressure rises and almost immediately closes the AV valve.
  • Ventricular pressure increases above aortic pressure and Aortic semilunar valve opens and ventricular ejection occurs
  • The Ventrical does not empty completely, the remaining blood is called end systolic volume (ESV)
  • As blood flows into the aorta, aortic pressure rises along with ventricular pressure however pressure begins to fall due to blood flow tapering off.
20
Q

What is diastole?

A

Period of ventricular relaxation

21
Q

What is happening during Mid to Late diastole?

A
  • Left atrium and left ventricle are both relaxed
  • AV valve is open and blood enters from pulmonary veins into atrium then about 70-80% of blood passes through open AV valve to ventricle before atrial contraction.
  • At the very end of diastole, SA node fires and atrium depolarizes, contracts and the remaining blood is added to the ventricle. (EDV)
22
Q

What is the EDV?

A

The ammount of blood in the ventricle just prior to systole.

23
Q

What is happening to cause the heart sounds in labels 1, 2, 3, and 4?

A
  1. Semilunar valve opens
  2. Semilunar Valve closes
  3. AV valve closes
  4. AV valve opens
24
Q

Explain what happens during Late Diatstole (mechanically)?

A

Both sets of chambers are relaxed and ventricles fill passively

25
Q

What happens during Atrial systole (mechanically)?

A

Atrial contraction forces a small ammount of additional blood into the ventricles

26
Q

What happens during isovolumetric ventricular contraction (mechanically)?

A

First phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves

27
Q

What happens during ventricular ejection (mechanically)?

A

as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected

28
Q

What hapens during isovolumetric ventricular relaxation (mechanically)?

A

As ventricles relax, pressure in ventricles falls, blood flows back into cusps of semilunar valves and snaps them closed

29
Q

Why is it important that majority of ventricular filling takes place in early diastole?

A

It ensures that ventricular filling is not seriously impaired during periods of increased heart rate as early diastole is shortened during an increase of HR.

30
Q

What 2 vessels branches off of the Aorta to supply the heart with blood?

A

Left and Right coronary artery

31
Q

During what mechanical event do coronary arteries recieve most of their blood flow? why?

A

Most of their blood flow occurs during diastole because during systole, the corronary arteries are compressed by the contracting myocardial mass and thier opening are partially blocked by the open aortic valve (70% blood flow during diastole, 30% during systole)

32
Q

During excersise, explain what happens to the blood flow in the coronary arteries and explain the efficiency of haemoglobin?

A

During excersise:

  • The heart uses almost all the oxygen (haemoglobin) brought to it by the corronary arteries (about 65%)
  • Only way to increase O2 Is by increase blood flow.
  • Matching the O2 requirement is critical because the heart cannot generate sufficient ATP through anaerobic processes.
33
Q

Explain the basic pathway of what happens regarding cardiac muscle cells requiring oxygen and its relation to ATP?

A

Metabolic Activity of cardiac muscle cells increase causing ATP use to increase; More oxygen is required ->

= Increase in Adenosine released ->

= Vasodilation of coronary vessels ->

= Increase in blood flow to cardiac muscle ->

= More oxygen availible to meet requirement

34
Q

What does the term anaerobic mean in relation to exercise?

A

An activity that cannot be sustained from the energy of oxygen alone, requires ATP (or another source of energy)

35
Q

What does the term aerobic mean in relation to exercise?

A

Activity that does not require any other energy source apart from Oxygen.

Integrative Physiology (9 decks)

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