Topic 6—A: Stimuli and Responses- 2. Nervous communication Flashcards
1
Q
Definition of receptors
A
- A cell or protein on a cell surface membrane that detects a stimulus
2
Q
Examples of types of receptors
A
- Baroreceptors- type of receptor that detects changes in blood pressure
(Receptors are specific to one type of stimulus)
3
Q
Definition of effectors
A
- A cell that brings about a response to a stimulus, to produce an effect
4
Q
Examples of effectors
A
- muscle cells
- cells found in glands e.g pancreas
5
Q
How do receptors communicate with effectors?
A
- via the nervous system or the hormonal system or sometimes using both
6
Q
What is the nervous system made up of?
A
- A complex network of cells called neurones
7
Q
What are the three main types of neurone?
A
- Sensory neurone
- Motor neurone
- Relay neurone
8
Q
Sensory neurone
A
- These transmit electrical impulses from receptors to the central nervous system (brain/spinal cord)
9
Q
Motor neurone
A
- Transmit electrical impulses from the central nervous system to effectors
10
Q
Relay neurone
A
- Transmit electrical impulses between sensory neurones and motor neurones
11
Q
Nervous communication
A
- stimulus is detected by receptor cells and an electrical impulse is sent along a sensory neurone
- When an electrical impulse reaches the end of a neurone chemicals called neurotransmitters take the information across the gap called a synapse to the next neurone where another electrical impulse is generated
- The CNS processes the information and sends impulses along motor neurones to an effector
12
Q
Example
A
- stimulus: you see a friend waving
- receptors: light receptors (photoreceptors) in your eyes detect the wave. The electrical impulse is carried by a sensory neurone to CNS.
- CNS: processes information and send an electrical impulse along a motor neurone
- effectors: muscle cells are stimulated by the motor neurone
Response- muscles contract to make your arm wave
13
Q
The nervous response
A
- when an electrical impulse reaches the end of a neurone chemical messengers called neurotransmitters are secreted directly onto cells e.g muscle cells – so the nervous response is localised
- neurotransmitters are quickly removed once they’ve done their job so the response is short-lived
- Electrical impulses are really fast so the response is usually rapid
- This allows animals to react quickly to stimuli
14
Q
Simple reflexes
A
- it is a rapid involuntary response to a stimulus
- The pathway of communication goes through the spinal cord but not through conscious parts of the brain so the response happens automatically
- Because you don’t have to spend time deciding on how to respond information travels really fast from receptors to effectors
- they are protective- they help organisms to avoid damage to the body because the response happens so quickly
15
Q
Reflex arc
A
- The pathway of neurones linking receptors to effectors in a simple reflex is called a reflex ark.
- three neurones are involved
- Sensory
- Relay
- Motor