Nervous Communication Flashcards
How do organisms respond to changes in their environment?
They need to pass information between different areas of its body.
How is information passed in animals?
Communication is carried out using nerve impulses.
What do receptors do?
They detect stimuli.
What can receptors be?
Cells, or proteins on cell surface membranes.
What is an example of a receptor?
Baroreceptors, which detect changes in blood pressure.
What are receptors specific to?
One type of stimulus.
What are effectors?
Cells that bring about a response to a stimulus, to produce an effect.
What are examples of effectors?
- Muscle cells
* Cells found in glands (e.g. pancreas)
How do receptors communicate with effectors?
Via the nervous system or hormonal system (sometimes both).
What is the nervous system made up of?
A complex network of cells called neurones.
What are neurones?
Nerve cells
What are the three main types of neurones?
- Sensory neurones.
- Relay neurones
- Motor neurones
What do sensory neurones do?
They transmit electrical impulses from receptors to the central nervous system (CNS) (the brain and spinal cord).
What do relay neurones do?
(intermediate neurones/interneurones) They transmit electrical impulses between sensory neurones and motor neurones.
What do motor neurones do?
They transmit electrical impulses from the CNS to effectors.
What happens during the pathway of nervous communication?
- A stimulus is detected by receptor cells
- 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 (synapse).
- To the next neurone where another electrical impulse is generated.
- The CNS (the coordinator) processes the information and sends impulses along motor neurones to an effector.
What does the pathway of nervous communication look like?
image
What are electrical impulses sent along neurones also called?
Nerve impulses or action potentials.
What happens 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.
What happens to neurotransmitters once they have completed their job?
They are quickly removed, so the response is short-lived.
How can animals react quickly to stimuli?
Electrical impulses are really fast, so the response is usually rapid.
What is a simple reflex?
A rapid, involuntary response to a stimulus.
What happens during simple reflexes?
The pathway of communication goes through the spinal cord, but not the conscious parts of the brain, so the response happens automatically.
Why do simple reflexes not go through the conscious parts of the brain?
Because simple reflexes are protective.
Why are simple reflexes protective?
They help organisms to avoid damage to the body because the response happens so quickly.
Why is a simple reflex automatic?
Because you don’t have to spend time deciding how to respond, as the information travels really fast from receptors to effectors.
What is a reflex arc?
The pathway of neurones linking receptor to effectors in a simple reflex.
What does the pathway of nervous communication in a simple reflex arc look like?
image
What are the cells neurotransmitters are released onto called?
Target cells (they have specific receptors for neurotransmitters).
What is an example of a simple reflex?
The hand-withdrawal response to heat:
•You touch a hot surface
•Thermoreceptors in your skin detect the heat stimulus.
•A sensory neurone carries the impulse to the CNS
•In the CNS a relay neurone in your spinal cord carries the impulse to a motor neurone.
•The motor neurone carries the impulse to muscle cells in your biceps.
•Your bicep contracts to pull your hand away from the heat source.
What could happen when there is a relay neurone involved in a simple reflex arc?
Then it is possible to override the reflex (e.g. your brain could tell your hand to withstand the heat).
What is a voluntary nervous response?
An impulse that involves the conscious brain.
What is an involuntary nervous response?
Reflexes that don’t involve the conscious brain.
