SB2g,i Flashcards
(17 cards)
What is the central nervous system (CNS) and what is it made up of?
The central nervous system is an organ system that allows all parts of the body to communicate, using impulses (electrical signals). It is formed by the brain and spinal cord, and nerves make up the rest of the nervous system.
What is a stimulus?
Anything our body is sensitive to, including changes inside the body and in our surroundings.
How can we detect stimuli?
Sense organs (such as eyes, ears and skin) contain receptor cells that detect stimuli. For example, skin contains receptor cells that detect the stimulus of temperature change.
How do we create a response?
Receptor cells create impulses which usually travel to the brain. The brain processes this information and can send impulses to other parts of the body to cause something to happen (a response).
What is and where does neurotransmission occur?
The travelling, or transmission, of impulses that happens in neurones.
What does a sensory neurone consist of? (6)
- Dendron
- Axon
- Dendrite
- Axon terminal
- Myelin sheath
- Cell body (contains nucleus)
Check Biology book page 43.
What is the function of a sensory neurone?
To carry impulses from receptor cells towards the CNS (central nervous system).
How do sensory neurones carry impulses?
A receptor cell impulse passes into the dendrite. It is then transmitted along the dendron and the axon. Axon terminals allow impulses to be transmitted to other neurones.
What are features and adaptations of the sensory neurone?
Dendrons and axons are long, to allow fast neurotransmission over long distances.
The myelin sheath (fatty layer surrounding dendrons and axons) electrically insulates a neurone from neighbouring neurones (e.g. in a nerve), stopping the signal losing energy. Also speeds up neurotransmission by making an impulse ‘jump’ along the cell between gaps in the myelin sheath.
What is an effector?
A muscle or gland (e.g. sweat glands) that carries out an action when an impulse from the nervous system is received in response to a stimulus.
What are the functions of a motor and relay neurone?
Motor neurones carry impulses to effectors.
Relay neurones are short neurones that are found in the spinal cord, where they link motor and sensory neurones.
What does a motor neurone consist of? (5)
- Axon
- Axon terminals
- Dendrites
- Myelin sheath
- Cell body at start
Check Biology book page 46.
What does a relay neurone consist of? (4)
- Axon
- Axon terminals
- Dendrites
- Cell body at start
Check Biology book page 46.
What is a synapse and what happens there?
A synapse is the point at which two neurones meet and contains a tiny gap between the neurones. When an impulse reaches an axon terminal, a neurotransmitter substance is released into the gap. This is detected by the next neurone, which generates a new impulse.
What are the advantages and disadvantages of synapses?
Advantages:
Neurotransmitters are only released from axon terminals so impulses only flow in one direction.
Allow many fresh impulses to be generated - the original impulse doesn’t need to split and lose ‘strength’.
Disadvantages:
Synapses slow down neurotransmission.
What are reflexes and how do they happen?
Reflexes are extremely quick, automatic responses that protect the body using neurone pathways called reflex arcs.
Check Biology book page 47.
Why do reflexes use reflex arcs?
Reflex arcs bypass the parts of the brain involved in processing information and so are quicker than responses that need processing.
