ORTCITIAEE: Control of heart rate

Question 1

What happens in the diastole stage of the cardiac cycle?

Answer 1

Atria relaxed
Ventricles relaxed

(the heart is resting at this stage)

Question 2

What happens in the atrial systole stage of the cardiac cycle?

Answer 2

Atria contract
Ventricles relaxed

Question 3

What happens in the ventricular systole stage of the cardiac cycle?

Answer 3

Atria relaxed
Ventricles contract

Question 4

Give the 3 stages of the cardiac CYCLE:

Answer 4

1) Diastole
2) Atrial systole
3) Ventricular systole

cycle then repeats!!!

Question 5

The cardiac cycle begins with the heart at rest. This stage is called ______.

Answer 5

Diastole

Question 6

When we want to move a muscle, our body generates a small amount of electricity called an _______ _______.

Answer 6

electrical impulse

Question 7

electrical impulses are sent from our brain down a sequence of _____.

Answer 7

Neurones

Question 8

Cardiac muscles are stimulated by an electrical impulse from where?

Answer 8

The cardiac muscle itself.

Question 9

When a muscle contracts due to impulses from the nervous system is is initiated by an ______ stimulus.

Answer 9

External

Question 10

When a muscle initiates its own contraction, it is initiated by a _____ stimulus.

Answer 10

myogenic

Question 11

Cardiac muscle is myogenic. What does this mean?

Answer 11

It stimulates its own contraction.

Question 12

Where is the sinoatrial node (SAN) found?

Answer 12

Right atrium

Question 13

What does the sinoatrial node (SAN) do?

Answer 13

Creates electrical impulses

Question 14

How is the atrial systole stage stimulated?

Answer 14

• The sinoatrial node stimulates electrical impulses which travel across the atria causing them to contract (both the left and right atria even though the SAN is only found in the right).
• This contraction forces blood out of the atria into the ventricles.

Question 15

What is another name given to the electrical impulses created by the SAN?

Answer 15

Wave of depolarisation

Question 16

Where do the electrical impulses produced by the sinoatrial node travel to ?

Answer 16

The atrioventricular node (AVN)

Question 17

Electrical impulses generated in the sinoatrial node travel to the atrioventricular node. Where do they travel next?

Answer 17

Bundle of His

Question 18

What is the Bundle of His made from?

Answer 18

Purkyne tissue

Question 19

What does the Bundle of His do?

Answer 19

• The structure of it travels down the middle of the heart (between the two halves) and around the ventricles
• Electrical impulses that travel down the ventricles to the bottom base of the heart, and up towards the ventricles.
• This stimulates ventricular systole, causing the ventricles to contract

Question 20

In which stage of the cardiac cycle are both the atria and ventricles relaxed?

Answer 20

Diastole

Question 21

The sinoatrial node triggers the ____ to contract.

Answer 21

Atria

Question 22

Why is the transmission of electrical impulses from the sinoatrial node to the atrioventricular node slightly delayed (1/10th of a second)?

Answer 22

Allows for blood in the atria to fully empty into the ventricles.

Question 23

Purkyne tissues conducts electrical impulses that cause the _______ to contract.

Answer 23

ventricles

Question 24

Why don’t the electrical impulses produced in the atria enter the ventricles?

Answer 24

• There is a layer of non-conductive tissue between the atria and ventricles.
• Ensures that the ventricles do not contract at the same time as the atria.

Question 25

The electrical impulse travels from the sinoatrial node to the atrioventricular node with a _____ of 1/10th of a second.

Answer 25

delay (this delay ensures that all the blood has left the atria and goes into the ventricle)

Question 26

What are the two branches of the autonomic nervous system?

Answer 26

- Sympathetic - Parasympathetic

Question 27

During rest our ________ branch within the autonomic nervous system is activated.

Answer 27

parasympathetic

Question 28

During distress our ________ branch within the autonomic nervous system is activated.

Answer 28

sympathetic

Question 29

Is the parasympathetic or sympathetic nervous system responsible for a stress response?

Answer 29

sympathetic

Question 30

What are the two types of receptors that send impulses to the medulla?

Answer 30

- Chemoreceptors - Pressure receptors

Question 31

Where are chemoreceptors located?

Answer 31

In the walls of blood vessels

Question 32

What do chemoreceptors do?

Answer 32

Detect changes in blood pH

Question 33

Where are pressure receptors located?

Answer 33

Neck and heart

Question 34

What do pressure receptors do?

Answer 34

Detect changes in blood pressure.

Question 35

Which part of the nervous system regulates involuntary processes such as heart rate?

Answer 35

Autonomic nervous system

Question 36

The sympathetic nervous system _______ effectors and increases processes such as heart rate.

Answer 36

stimulates

Question 37

The parasympathetic nervous system ______ effectors and slows processes such as heart rate.

Answer 37

inhibits

Question 38

What is the body’s cardiac control centre?

Answer 38

Medulla oblongata

Question 39

How does the body correct low blood pH?

Answer 39

- Low blood pH is detected by chemoreceptors. - These receptors send impulses along the sympathetic pathway. - These impulses arrive at the medulla oblongata which sends further impulses to the SAN to increase heart rate.

Question 40

How does the body correct high blood pressure?

Answer 40

- High blood pressure is detected by pressure receptors. - These receptors send impulses along the parasympathetic pathway - These impulses arrive at the medulla oblongata which sends further impulses to the SAN to decrease heart rate.