Paper 2: Topic 5 Homeostasis & response - Nervous system (LV) Flashcards Preview

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Flashcards in Paper 2: Topic 5 Homeostasis & response - Nervous system (LV) Deck (107)
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1

Why do single-celled organisms not need a nervous system?

They can respond to changes in their environment easily and directly

2

Why does a multi-cellular organism need a nervous system?

  • So that they can react to changes in their environment AND control and regulate changes in the different part of the body
  • The nervous system allows cells to communicate with each other so a controlled response occurs
  • A nervous system ensures co-ordinated behaviour

3

What structures are the main parts of the central nervous system?

  • Brain
  • Spinal cord

4

Describe how the central nervous system is connected to the other parts of the body?

Sensory and motor neurones

5

Define the term receptor

A cell that detects a stimulus (change in the environment)

AND

that can generate/produce a nerve impulse

6

State 4 different types of receptor

  • Sound receptors
  • Light receptors
  • Chemical receptors
  • Pressure receptors

7

Define the term effector

A muscle or gland that responds to nerve impulses and cause a response

8

State how muscles respond to nerve impulses

They contract

 

HINT: do NOT write they "contract AND RELAX" - the impulse only causes them to contract

9

State how glands respond to nerve impulses

Glands secrete a hormone into the plasma

10

State the function of the central nervous system

To receive and process information from the receptors AND

to co-ordinate the response

11

Write the pathway of a nerve impulse from stimulus to response (reflex arc)

Stimulus → receptor -→ sensory neurone → central nervous system → motor neurone → effector → response

12

Explain why not all multi-cellular organisms have a nervous system

Only large, multi-cellular organisms have a nevous system

Small multi-cellular organsims e.g. jelly fish rely on reflex reponses

13

State the function of a neurone

To transmit a nerve impulse

14

Define the term 'synapse'

A junction between two neurones

15

Describe how a nerve impulse is transmitted across a synapse

  • Neurotransmiters are released into the synapse from the synaptic knob
  • The neurotransmitters diffuse across the synapse
  • The neurtransmitters bind to receptors on the membrane of the next neurone
  • And this then triggers the nerve impulse in the neurone

16

Define the term neurotransmitter

A specialised chemical that is released from the end of the axon of one neurone that can diffuse across a synapse to trigger a nerve impulse in the next neurone

17

Explain the purpose of reflex actions

To prevent damage or harm to the organism

18

State 5 examples of relex actions

  • Blinking
  • Coughing
  • Sneezing
  • Vomiting
  • Knee-jerk

19

Describe a reflex arc

Hint: 6 main stages

  1. A change in the environment occurs (a stimulus)
  2. A receptor cell detects the stimulus
  3. A nerve impulse is sent along the sensory neurone to the CNS
  4. The nerve impulse is passed through the relay neurone in the CNS
  5. The nerve impulse is sent along a motor neurone to the effector
  6. The effector brings about a response

20

What is the role/function of a sensory neurone?

To transmit a nerve impulse from the receptor to the relay neurone

21

What is the role/function of a relay neurone?

To transmit a nerve impulse from the sensory neurone to the motor neurone

22

What is the role/function of a motor neruone?

To transmit a nerve impulse from the relay neurone to the effector

23

Explain the advantage of using reflex actions

  • Quicker response time i.e. rapid response
  • Which reduces damage and harm to the organism

24

Define a reflex action

 

Hint:

This is a similar question to "state the charcateristics of a reflex action"

A rapid, automatic response that does not involve the conscious part of the brain

 

Characteristics of a reflex action:

  • rapid / fast
  • involuntary response i.e. subconcious

25

State which 2 parts of the CNS a reflex arc may pass through

The spinal cord

OR

An unconscious part of the brain

26

Define the term reaction time

The time it takes to respond to a stimulus

27

State 4 factors that can affect the reaction time

  • Age
  • Alcohol
  • Gender
  • Drugs e.g. caffeine

28

Describe the effect caffeine has a person’s reaction time

  • Speeds the reaction time up
  • i.e. time to respond to a stimulus decreases

29

Describe the effect alcohol has a person’s reaction time

  • Slows down the reaction time
  • i.e. time to respond to a stimulus increases

30

Describe how a person’s reaction time can be measured

  • Use the dropping a ruler technique

OR

  • Use a computer programme

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