Biology - 10 The Human Nervous System - 10.1 Principles of Homeostasis & 10.2 The Structure and Function of the Human Nervous System & 10.3 Reflex Actions

Homeostasis

the tendency to maintain a constant internal state

Why is temperature regulated?

to keep the enzymes of the body at their optimum temperature

What internal conditions are controlled? [3]

- body temperature
- water content of the body
- blood glucose concentration

Receptor

a cell that detects a change in a condition

Effector

an organ or cell that acts in response to a stimulus.

Stimuli

changes in the environment

Coordination centre

receives and processes the information then organises a response

Neurone

a cell that transmits electrical impulses in the nervous system

Nerve

a bundle of neurones

Central nervous system

brain and spinal cord

Sensory neurone

carries impulses from receptor to CNS

Motor neurone

carries impulse from CNS to effector

Nervous system process [7]

- stimulus
- receptor
- sensory neurone
- coordinator (CNS)
- motor neurone
- effector
- response

Reflex

an automatic response to a sensory stimulus

What do reflexes skip?

the conscious mind

What do reflexes do? [2]

- respond to dangerous stimuli
- control unconscious body functions

Relay neurone

short neurone that connects sensory and motor neurones

Where are most relay neurones?

in the spinal cord

Reflex arc

the nerve pathway involved in a reflex action

Reflex arc components [7]

- stimulus
- receptor
- sensory neurone
- relay neurone
- motor neurone
- effector
- response

Synapse

a junction where information is transmitted from one neuron to the next.

How does an impulse travel across a synapse?

neurotransmitters carry it across the gap

Neurotransmitter

chemical messengers that cross the synaptic gaps between neurons