6A - Nervous communication

Question 1

How do animals increase their chances of survival?

Answer 1

By responding to changes in their external environment.

Question 2

As well as responding to changes in their external environment, what do animals also respond to?

Answer 2

Changes in their internal environment.

Question 3

Why do animals respond to changes in their external environment?

Answer 3

To increase their chances of survival.

Question 4

Why do animals respond to changes in their internal environment?

Answer 4

To make sure that the conditions are always optimal for their metabolism (all the chemical reactions that go on inside them).

Question 5

How do plants increase their chances of survival?

Answer 5

By responding to changes in their environment.

Question 6

Why do plants respond to changes in their environment?

Answer 6

To increase their chances of survival.

Question 7

Any change in the internal or external environment is called what?

Answer 7

A stimulus.

Question 8

What is a stimulus?

Answer 8

Any change in the internal or external environment.

Question 9

What do receptors do?

Answer 9

Detect stimuli.

Question 10

What are receptors?

Answer 10

Cells or proteins on cell surface membranes.

Question 11

Do receptors detect any stimuli?

Answer 11

There are loads of different types of receptors that detect different stimuli.

Question 12

What are receptors specific to?

Answer 12

One type of stimulus.

Question 13

What are effectors?

Answer 13

Cells that bring about a response to a stimulus, to produce an effect.

Question 14

What do effectors include?

Answer 14

Muscle cells and cells found in glands, e.g. the pancreas.

Question 15

What do receptors do apart from detecting stimuli?

Answer 15

Communicate with effectors via the nervous system or the hormonal system, or sometimes using both.

Question 16

How do receptors communicate with effectors?

Answer 16

Via the nervous system or the hormonal system, or sometimes using both.

Question 17

What does the nervous system do?

Answer 17

Sends information as electrical impulses.

Question 18

What is the nervous system made up of?

Answer 18

A complex network of cells called neurones.

Question 19

How many main types of neurons are there?

Answer 19

3

Question 20

What are the 3 main types of neurones?

Answer 20

Sensory, relay/intermediate, motor neurons.

Question 21

What is another name for relay neuron?

Answer 21

Intermediate neuron

Question 22

What is an intermediate neuron also called?

Answer 22

Relay neuron

Question 23

What do sensory neurons do?

Answer 23

Transmit electrical impulses from receptors to the central nervous system.

Question 24

What is the CNS made of?

Answer 24

Brain and spinal cord.

Question 25

What does the brain and spinal cord make up?

Answer 25

CNS.

Question 26

What do motor neurons do?

Answer 26

Transmit electrical impulses from the CNS to effectors.

Question 27

What do relay neurons do?

Answer 27

Transmit electrical impulses between sensory neurons and motor neurons.

Question 28

What type of neuron transmits electrical impulses from receptors to the central nervous system?

Answer 28

Sensory neurones.

Question 29

What type of neuron transmits electrical impulses from the CNS to effectors?

Answer 29

Motor neurones.

Question 30

What type of neuron transmits electrical impulses between sensory neurons and motor neurons?

Answer 30

Relay/intermediate neurones.

Question 31

What are electrical impulses also called?

Answer 31

Nerve impulses or action potentials.

Question 32

Explain how information is sent through the nervous system to produce a response

Answer 32

- A stimulus is detected by receptor cells and an electrical impulse is sent along a sensory neuron. - When an electrical impulse reaches the end of a neuron, chemicals called neurotransmitters take the information across to the next neuron, which then sends an electrical impulse. - The CNS (the coordinator) processes the information and sends impulses along motor neurones to an effector.

Question 33

Draw a flow diagram to show how information is sent through the nervous system to produce a response

Answer 33

``` Stimulus Receptors CNS (sensory --> relay --> motor) Effectors Response ```

Question 34

Briefly explain the structure of the nervous system

Answer 34

CNS = brain and spinal cord Peripheral NS (CNS + neurons) is split into: - Somatic NS (controls conscious activities). - Autonomic NS ( controls unconscious activities). Autonomic NS is split into: - Sympathetic NS (fight-or-flight). - Parasympathetic (rest and digest).

Question 35

Describe characteristics of reflexes

Answer 35

Automatic/rapid Don't involve conscious brain areas Consists of only 3 neurons

Question 36

Explain the transmission of the nerve impulse in a reflex arc

Answer 36

Receptor --> sensory neuron --> CNS (Relay neuron) --> motor neuron --> effector. 1. Receptor 2. Sensory neuron 3. Integration centre 4. Motor neuron 5. Effector

Question 37

In a nerve cells where is the impulse transmitted to and from?

Answer 37

Dendron --> cell body --> axon

Question 38

In which direction does the axon take the nerve impulse?

Answer 38

Away from the cell body.

Question 39

What is a reflex?

Answer 39

Where the body responds to a stimulus without making a conscious decision to respond.

Question 40

Why does information travel really fast from receptors to effectors in a reflex arc?

Answer 40

Because you don't have to spend time deciding how to respond.

Question 41

Why do simple reflexes help organisms to protect the body?

Answer 41

Because they're rapid.

Question 42

What is the pathway of neurones linking receptors to effectors in a reflex called?

Answer 42

A reflex arc.

Question 43

Explain the reflex arc occuring when a hand withdraws in response to heat

Answer 43

- Thermoreceptors in the skin detect the heat stimulus. - The sensory neuron carries impulses to the relay neuron. - The relay neuron connects to the motor neuron. - The motor neuron sends impulses to the effector (your biceps muscle). - Your muscle contracts to withdraw your hand and stop it being damaged.

Question 44

What is it possible to do if a relay neuron is involved in the simple reflex arc?

Answer 44

It's possible to override the reflex, e.g. your brain could tell your hand to withstand the heat.

Question 45

Give an example of a stimulus

Answer 45

You see a friend waving.

Question 46

Give an example of a receptor

Answer 46

Light receptors (photoreceptors)

Question 47

What type of neuron are muscles stimulated by?

Answer 47

Motor neurones.

Question 48

Give characteristics of nervous system communication

Answer 48

Localised Short-lived Rapid

Question 49

Why is nervous system communication localised?

Answer 49

When an electrical impulse reaches the end of a neurone, neurotransmitters are secreted directly onto target cells (e.g. muscle cells) - so the nervous response is localised.

Question 50

Why is nervous system communication short-lived?

Answer 50

Neurotransmitters are quickly removed once they've done their job, so the response is short-lived.

Question 51

Why is nervous system communication rapid?

Answer 51

Electrical impulses are really fast, so the response is rapid - this allows animals to react quickly to stimuli.

Question 52

What does the nervous response being rapid allow animals to do?

Answer 52

React quickly to stimuli.