6A - Nervous communication Flashcards
How do animals increase their chances of survival?
By responding to changes in their external environment.
As well as responding to changes in their external environment, what do animals also respond to?
Changes in their internal environment.
Why do animals respond to changes in their external environment?
To increase their chances of survival.
Why do animals respond to changes in their internal environment?
To make sure that the conditions are always optimal for their metabolism (all the chemical reactions that go on inside them).
How do plants increase their chances of survival?
By responding to changes in their environment.
Why do plants respond to changes in their environment?
To increase their chances of survival.
Any change in the internal or external environment is called what?
A stimulus.
What is a stimulus?
Any change in the internal or external environment.
What do receptors do?
Detect stimuli.
What are receptors?
Cells or proteins on cell surface membranes.
Do receptors detect any stimuli?
There are loads of different types of receptors that detect different stimuli.
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 do effectors include?
Muscle cells and cells found in glands, e.g. the pancreas.
What do receptors do apart from detecting stimuli?
Communicate with effectors via the nervous system or the hormonal system, or sometimes using both.
How do receptors communicate with effectors?
Via the nervous system or the hormonal system, or sometimes using both.
What does the nervous system do?
Sends information as electrical impulses.
What is the nervous system made up of?
A complex network of cells called neurones.
How many main types of neurons are there?
3
What are the 3 main types of neurones?
Sensory, relay/intermediate, motor neurons.
What is another name for relay neuron?
Intermediate neuron
What is an intermediate neuron also called?
Relay neuron
What do sensory neurons do?
Transmit electrical impulses from receptors to the central nervous system.
What is the CNS made of?
Brain and spinal cord.
What does the brain and spinal cord make up?
CNS.
What do motor neurons do?
Transmit electrical impulses from the CNS to effectors.
What do relay neurons do?
Transmit electrical impulses between sensory neurons and motor neurons.
What type of neuron transmits electrical impulses from receptors to the central nervous system?
Sensory neurones.
What type of neuron transmits electrical impulses from the CNS to effectors?
Motor neurones.
What type of neuron transmits electrical impulses between sensory neurons and motor neurons?
Relay/intermediate neurones.
What are electrical impulses also called?
Nerve impulses or action potentials.
Explain how information is sent through the nervous system to produce a response
- 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.
Draw a flow diagram to show how information is sent through the nervous system to produce a response
Stimulus Receptors CNS (sensory --> relay --> motor) Effectors Response
Briefly explain the structure of the nervous system
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).
Describe characteristics of reflexes
Automatic/rapid
Don’t involve conscious brain areas
Consists of only 3 neurons
Explain the transmission of the nerve impulse in a reflex arc
Receptor –> sensory neuron –> CNS (Relay neuron) –> motor neuron –> effector.
- Receptor
- Sensory neuron
- Integration centre
- Motor neuron
- Effector
In a nerve cells where is the impulse transmitted to and from?
Dendron –> cell body –> axon
In which direction does the axon take the nerve impulse?
Away from the cell body.
What is a reflex?
Where the body responds to a stimulus without making a conscious decision to respond.
Why does information travel really fast from receptors to effectors in a reflex arc?
Because you don’t have to spend time deciding how to respond.
Why do simple reflexes help organisms to protect the body?
Because they’re rapid.
What is the pathway of neurones linking receptors to effectors in a reflex called?
A reflex arc.
Explain the reflex arc occuring when a hand withdraws in response to heat
- 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.
What is it possible to do if a relay neuron is involved in the simple reflex arc?
It’s possible to override the reflex, e.g. your brain could tell your hand to withstand the heat.
Give an example of a stimulus
You see a friend waving.
Give an example of a receptor
Light receptors (photoreceptors)
What type of neuron are muscles stimulated by?
Motor neurones.
Give characteristics of nervous system communication
Localised
Short-lived
Rapid
Why is nervous system communication localised?
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.
Why is nervous system communication short-lived?
Neurotransmitters are quickly removed once they’ve done their job, so the response is short-lived.
Why is nervous system communication rapid?
Electrical impulses are really fast, so the response is rapid - this allows animals to react quickly to stimuli.
What does the nervous response being rapid allow animals to do?
React quickly to stimuli.
