Lecture 10 Flashcards

1
Q

What is the organ responsible for the circulation of blood?

A

The heart

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

Where is the heart found?

A

In a cavity in the thorax called the pericardium

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

Where is the heart attached to the pericardium?

A

Only where the big vessels enter and leave

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

What is the pericardium lined by?

A

A layer of simple squamous epithelium called the mesothelium (forms part of the pericardial membrane)

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

What is the outer covering of the heart called?

A

The epicardium and it’s covered by a mesothelium

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

What do ‘Lub’ and ‘Dub’ refer to?

A

The two heart sounds heard when using a stethoscope

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

What is ‘Lub’ caused by?

A

The closing of the bicuspid and tricuspid valves between the left and right atria and ventricles respectively, during ventricular systole

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

What is ‘Dub’ caused by?

A

The closing of semilunar valves in the pulmonary artery and the aorta, at the beginning of ventricular diastole

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

What can be detected by listening to the heart sounds?

A

Damaged valves and heart murmurs

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

Layers of heart?

A

Endocardium-myocardium-epicardium-pericardial cavity-pericardium

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

Endocardium?

A

In direct contact with the blood

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

Myocardium?

A

The muscles in the heart

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

Cardiac muscle?

A
  • Striated
  • Arranged into individual cells that are separated by areas of intercalated disks (membranes with gap junctions that allow a free diffusion of ions from cell to cell)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

To allow proper timing of the heart beat, cardiac muscle…?

A
  • Is myogenic
  • Functions as a syncytium
  • Has a long refractory period
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Myogenic?

A

The heart can contract rhythmically and continuously without external stimulation

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

Syncytium?

A

The action potential spreading from cell to cell

17
Q

Refractory period?

A

A period after stimulus during which no further contraction may take place (0.25 – 0.3 sec)

18
Q

What is the heart rate regulated by?

A

The cardiac centre

19
Q

Where is the cardiac centre?

A

In the medulla oblongata

20
Q

What does the medulla oblongata respond to?

A

To pressure receptors in the walls of blood vessels

21
Q

Is the rate of heart beats lower in larger animals?

22
Q

Discuss the adult human rate of heart beat?

A
  • Normally contracts at about 72 beats/min
  • It may rise to 195 beats/min under stress
  • Trained athletes tend to have lower resting heart rates (50/min)
23
Q

Where do contractions begin?

A

The sino-atrial node

24
Q

Why does the heart have a long refractory period?

A

Bc it allows it to be more coordinated