Impulses

Question 1

What are the 10 events in a reflex.

Answer 1

Stimulus -> Receptor -> Sensory neurone -> Synapse -> Relay neurone -> Synapse -> Motor neurone -> Neuromuscular junction -> Effector -> Response

Question 2

What is the receptor when the stimulus is ‘external or internal temperature’?

Answer 2

Thermo-receptor

Question 3

What is the receptor when the stimulus is the ‘level of water in the blood’?

Answer 3

Osmoreceptor

Question 4

What is the receptor when the stimulus is ‘bright light’?

Answer 4

Cone cell

Question 5

What is the receptor when the stimulus is ‘dim light’?

Answer 5

Rod cell

Question 6

What is the receptor when the stimulus is ‘blood pressure’?

Answer 6

Bara receptor

Question 7

What is the receptor when the stimulus is ‘carbon dioxide in the blood’?

Answer 7

Chemoreceptor

Question 8

What is the reflex arc process for an increase in heart rate?

Answer 8

1. There’s a normal concentration of CO2 in the blood.
2. Chemoreceptors detect a rise in CO2 levels in the blood (through repairing muscles).
3. Sensory neurone to the coordinator (which is the medulla).
4. Motor neurone to the effector.
5. This causes an increase in heart rate and stroke volume.
6. This leads to a normal concentration of CO2 in the blood again.

Question 9

What is the reflex arc process for a decrease in heart rate?

Answer 9

1. Normal concentration of CO2 in the blood.
2. Chemoreceptors in the aortic arch detect fall in CO2 levels in blood.
3. This leads to impulses in the sensory neurones.
4. This leads to coordinator in the medulla.
5. This impulses in motor neurone.
6. Leading to a decrease in heart rate and stroke volume.
7. This ends in a normal concentration of CO2 in blood

Question 10

What are reflexes needed for?

Answer 10

To protect from danger and maintain pressure.

Question 11

Why are reflexes fast?

Answer 11

Because of the minimum number of synapses and neurones.

Question 12

What do motor neurones do?

Answer 12

Transmit electrical impulses from the CNS to the effector.

Question 13

What is a synapse?

Answer 13

The physical gap between two neurones.

Question 14

What is noradrenaline?

Answer 14

Noradrenaline is a chemical which is secreted onto the SAN when the heart rate needs to increase.

Question 15

Define resting potential.

Answer 15

The potential across the plasma membrane of a cell that is not conducting an impulse.

Question 16

How do you calculate cardiac output?

Answer 16

Stroke volume x heart rate.

Question 17

What does the sympathetic nervous system do?

Answer 17

• increases HR and SV

- releases noradrenaline onto the SAN

Question 18

What does the parasympathetic nervous system do?

Answer 18

• decreases HR and SV
• decreases blood pressure
• releases acetylcholine onto the SAN

Question 19

What transport process is used by the sodium potassium pump?

Answer 19

Active transport

Question 20

Why is it important for the pupil to enlarge in dim light?

Answer 20

Because this allows rod cells to gain sufficient light energy to produce a greater generator potential.

Question 21

Why is it important for the pupil to become smaller in bright light?

Answer 21

To prevent damage to the retina due to too much light energy.

Question 22

Which three neurones are present in a reflex action?

Answer 22

Sensory, relay, motor.

Question 23

Why does the synapse only work in one direction?

Answer 23

• calcium ion channels are only found in the pre-synaptic nerve.
• receptors for neurotransmitters are only found in the post-synaptic nerve.
• vesicles containing neurotransmitters are only found in the pre-synaptic nerve.