Reflexes

Question 1

What are reflex actions?

Answer 1

Automatic actions that do not require conscious thought

Question 2

Why are reflex actions important?

Answer 2

To help protect us from harm

Question 3

What is the 5 step process that produces a reflex reaction?

Answer 3

1. Receptors
2. Sensory neuron
3. Relay neuron
4. Motor neuron
5. Effector

Question 4

Give 2 features of reflexes:

Answer 4

1. Reflexes need to be fast
2. Electrical signals bypass parts of the brain and travel down a relay neuron to speed up transmission

Question 5

What does a relay neuron do?

Answer 5

Transfers information from sensory to motor neurons

Question 6

Name 3 reflexes only observed in babies:

Answer 6

1. Palmar reflex
2. Moro reflex
3. Rooting reflex or sucking reflex

Question 7

What is an electrical impulse?

Answer 7

An electrical signal that travels along the axon of a neuron

Question 8

What is a presynaptic neuron?

Answer 8

The neuron that sends the signal across the synapse

Question 9

What is a vesicle?

Answer 9

A small membrane-bound sac that stores neurotransmitters

Question 10

What is a neurotransmitter?

Answer 10

A chemical messages released by neurons to transmit signals across a synapse

Question 11

What is a presynaptic neuron?

Answer 11

The membrane of the presynaptic neuron where vesicles release neurotransmitters

Question 12

What is a synapse?

Answer 12

The junction between 2 neurons where neurotransmitters are released to transmit signals

Question 13

What is a synapse?

Answer 13

The junction between 2 neurons where neurotransmitters are released to transmit signals

Question 14

What is a post-synaptic neuron?

Answer 14

The neuron that receives the signal after it crosses the synapse

Question 15

What is the post- synaptic membrane?

Answer 15

The membrane of the post-synaptic neuron that contains receptors for neurotransmitters.

Question 16

What is a post-synaptic receptor?

Answer 16

Proteins on the post-synaptic membrane that bind to neurotransmitters to receive the signal

Question 17

What is the knee jerk test?

Answer 17

Tapping on the knee stretching the muscle/tendon and the muscle contracts, lifting the leg.
Protects the muscle from overstretching

Question 18

What is the blink test?

Answer 18

Changing light levels and muscles cause the eye lid to close
Protects eye from potential damage

Question 19

What is the pupil response to light test?

Answer 19

Increased light and muscles cause the iris to get bigger, causing the pupil to get smaller
Protect the retina from excess light

Question 20

What is the pupil response to dark test?

Answer 20

Reduced light and muscle cause the iris to get smaller, causing the pupil to dilate
Allows more light to enter the eye, allowing the subject to see in poor light

Question 21

What is the ankle jerk reflex test?

Answer 21

Tap on the Achilles tendon, stretching the muscle and the calf muscle contracts, extending the door

Protects the calf muscle from overstocking

Question 22

How is the impulse transmitted? (5)

Answer 22

1. An impulse arrives at the end of the presynaptic nerve
2. Vesicles move towards and fuse with the presynaptic membrane. This releases neurotransmitters info the synaptic cleft
3. The neurotransmitters diffuse across the synaptic cleft (down a concentration gradient)
4. Neurotransmitters attach to receptors on the postsynaptic membrane
5. This triggers an impulse which travels along the postsynaptic neuron
6. The neurotransmitters are recycled or destroyed once an impulse is sent