Coordination and Response - Bio

Nerve impulse

An electrical signal that passes along nerve cells called neurones in one direction.

Central nervous system

Made up of the brain and spinal cord.

Peripheral nervous system

Made up of cranial and spinal nerves that connect the central nervous system to the body.

Cranial nerves

Nerves that connect the brain with all other organs in the head, thorax, and abdomen.

Spinal nerves

Nerves that connect the brain with the arms, thorax, abdomen, and legs.

Voluntary action

Reactions that we choose to make, which involve the brain, e.g., catching a ball.

Involuntary action

An automatic response that does not involve a decision or thought.

Reflex action

Automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands).

Neuron

Made up of lots of neurones or nerve cells.

Structure of a neurone

Long to transmit impulses over long distances, mitochondria to release energy for transmission, vesicles to release neurotransmitters.

Synapse

Junction between two neurones that ensures the impulse travels in one direction only.

Receptors

Cells that detect a stimulus.

Effectors

Muscles or glands that carry out the response to the stimulus.

Myelin

A layer rich in fat surrounding neurones, providing insulation and allowing impulses to travel quickly.

Negative feedback

A regulatory mechanism that returns a condition to its optimum, like body temperature to 37C.

Hormone

A chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs.

Adrenal gland

Secretes adrenaline, which allows the 'fight or flight' response by increasing heart rate and breathing rate.

Testosterone

A hormone secreted by the testes that stimulates secondary male features and body hair.

Oestrogen

A hormone secreted by the ovaries that controls the menstrual cycle and growth of breasts.

Homeostasis

The maintenance of a constant internal environment.

Glycogen

A complex carbohydrate/polysaccharide made up of many glucose molecules, stored in the liver and muscle cells.

Type 1 diabetes

Occurs when the body cannot produce insulin.

Gravitropism

A response in which parts of a plant grow towards or away from gravity.

Phototropism

A response in which parts of a plant grow towards or away from the direction from which light is coming.

Synthetic auxin

Used as weedkillers, absorbed by broad-leaved weeds which increase growth rate causing the plants to die.