HideShow resource information


Behaviour= responding to a stimulus

Voluntary behaviour= When you actively decide to respond to a stimulus (complex behaviour)

Involuntary behaviour= When you inactiveky decide to respond to a stimulus (simple behaviour)

Simple behaviour:

Single-celled amoeba move away from high concentrations of salt, strong acids and alkalies.

When a giant octupus sees a preditor, it rapidly contracts its body muscels. This squirts out ink pushing it away. This helps it to survive.

Human brains are capable of voluntary behavior due to evolution. Different parts of the brain do different jobs. For example the cerebral cortex is responsible for language, consciousness and itelligance

1 of 11

Newborn refexes

Stepping- If you hold a baby under the arms and allow its feet to touch the floor it tries to walk

Grasping- When you put your finger in a babys open palm the baby will grip the finger

Startle- This usually hapens when a baby hears a loud noise or is moved quickly. It responds by extending arms, legs and neck and then quickly bringing them back together

Sucking- By putting something in a babys mouth it instantly starts to ****

Rooting- Stroking a babys cheek makes it turn towards you looking for food

Swimming- If you put a baby under 6 months in water, it will move its arms and legs whilst holding its breath

Many of these reflexes are only present for a short time after birth. They are gradually replaced by learnt behaviours.

2 of 11

Simple reflexes in humans

Stimuli --> receptor --> processing center --> effector --> response

Receptors and effectors can sometimes form part of complex organs, for example:

the nervous system uses electrical impulses for fast, short-lived responses eg. light receptors in your eyes, muscel cells in a muscel (knee jerk)

hormones are chemicals that are produced in glands, travel in the blood and bring slower, longer-lasting responses eg. Insulin, ADH

These responses increase our chances of survival and are due to evolution

3 of 11


The central nervous system includes the brain and your spinal cord

The peripheral nervous system includes everything else eg. arms and legs

Nerves are bundles of specialised cells called neurons.


  • The axon is a long extention of the cytoplasm, it carried the impulses
  • The nucleus carries DNA with the data to make enzymes
  • The fatty sheath surrounding the axon insulates the neurone and increases the speed of the impulses
  • Branched endings make connections with other neurons or effectors
4 of 11

The reflex arc

The stimulus is detected by receptor cells in the skin. The nerve impulses are carried alomg a sensory neurone to the central nervous system. The nerve impulse travels across a synapse to a relay neurone which then passes the neve impulse across a synapse to a motor neurone. It bi-passes the brain making the response quicker and automatic. The nerve impulse travel along a motor neurone to an effector. The effecter carries out a response.

In some circumstances the brain can modify a reflex response, via a neuron to the motor neurone of the reflex arc eg. keeping hold of a hot plate

5 of 11


A nerve impulse arrives at the synapse along the pre-synaptic neurone. The impulse stimulates neurotransmitters (stored in vesicals) to be released through channels into the synapse.

The neurotransmitter (eg.serotonin) diffuses across the synapse

The neurotransmitter binds with a receptor on the membrance of the post-synaptic neurone. There is a complementary fit.

Binding of the nerotransmitter to the receptor stimulates impulses in post synaptic neutrons. The neurotransmitter is then re-absorped via the channels

6 of 11

Effects of drugs on your body


Can be used as an anti-depressant as it blocks the channels for the re-up take of the neurotransmitter (in this case serotonin). As there is a build up serotonin this causes more nerve impulses as the chances of the serotonin bonding to the receptors is greater.


Ecstacy has simular effects to prozac but it can have negative short/long term effects such as anxiety, depression, poor memory and poor attention span.

Beta blockers:

Reduce the transmission of impulses across the synapses by blocking receptors. This reduces nerve impulses.

7 of 11

Learnt behaviour

Classical conditioning= associating a secoundary stimulus (regular) with a primary (mainly attractive) stimulus

Unconditioned stimulus= regular item

Conditioned stimulus= attractive stimuli's association

Conditioned response= action taken after the association of a product with an attractive stimuli

Eg. During a Cola advert coke (unconditioned stimulus) is associated with christmas (conditioned stimulus) and so people buy it (conditioned respinse)

8 of 11

Pavlov's experiment

Pavlov's dog salivated when presented with food. The food is the stimulus and salivation is the response

Pavlov rang a bell everytime his dog was eating it's food

After a while the dog salivated when it heard the bell, even if there was no food around. The dog learnt to link the stimulus of the bell ringing with the food. 

This type of learning is called conditioning

9 of 11

How does learning happen

Neuron pathways are how the neurons in your brain are connected.

If an experience is repeated, or the stimulus is particularly strong, the more nerve impulses that follow the same nerve pathway the connections get stronger making it easier to produce a response.

Visulisation enhances learning because the nerve pathways are already strengthened before you have done the action. Repetition enhances learning because you use the same pathways over again making it easier to do.

A variation of potential pathways in the brain allows animals to adapt to certain situations

Feral childen= children who are away from human interaction during the critical learning period of learning for children to learn languages and make sounds into words. Therefore, they cannot talk.

10 of 11



  • Short term memory lasts 30 seconds
  • Long term memory lasts up to a lifetime

Memory improves when grouping objects because it adds neuron pathways between objects. Memory also improves with linking objects because it connects all objects with one neuron pathway

We can tell short term and long term memory is stored seperately but people with alzheimers can remember there childhoods but not simple instructions

11 of 11


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all B6 resources »