2.  several main regions  - (1)Cerebrum  - responsible for thought, reasoning, imagination etc.  - (2) cerebellum  - controls balance & co- ordination  - (3) medulla  - controls breathing & heart rate  - (4) hypothalamus  - regulates water balance & body temperature  - (5) pituitary gland  - releases many hormones (e.g. ADH) (2) (3) (1) (5) (4)

3.  Made of 2 hemispheres  Each split into different regions  E.g. sensory & motor strips  Sensory areas receive impulses from sense receptors  The more receptors the body part has, the bigger the sensory area  The impulses are interpreted and a response passed to the motor areas  The more mobile the body part, the larger the motor area  Both illustrated by a homunculus

4. SENSORY MOTOR

5.  Brain, spinal cord, and nerves = Central Nervous System (CNS)  Nerve cells are called neurones  Neurones consist of a cell body attached to nerve fibres  The synapse is the space between two neurones  A sensory fibre takes impulses towards the CNS  A relay neurone passes the signal along the CNS  An axon fibre (motor neurone) that takes the response away Relay neurone

6.  Reflex is a rapid, involuntary response  e.g. hand contacting a hot surface  1) Pain receptors in the skin detect heat  2) Impulse sent along sensory neurone  3) Impulse crosses synapse to relay neurone & is passed along  4) Impulse crosses synapse to motor neurone  5) Motor neurone takes response signal to the axon endings  6) Signal is passed to the arm muscles & arm lifts

7.  Hypothalamus  - the body’s temperature monitoring centre  Receives nerve impulses from thermoreceptors in the skin  - to keep body shell at around 33oC  Also contains central thermoreceptors  - detect blood temp changes  - keeps core temp at 37oC  Hypothalamus responds by sending motor nerve impulses to effectors

8.  Acts in response to the hypothalamus  ‘Too hot’ - Promotes heat loss:  1) Increases sweating  - converts water in sweat to water vapour  2) Vasodilation  (arterioles get bigger)  - more blood flows to the skin surface  - more heat lost by radiation

9.  ‘Too cold’ - Corrects overcooling:  - Decreases rate of sweating  - Vasoconstriction  (arterioles become narrower)  - Less blood flow to skin surface  - less heat lost by radiation  - Erector muscles contract, hairs raised  - layer of air trapped next to skin

10.  Skeletal muscles undergo brief, repeated contractions  – SHIVERING  In the liver, metabolic reactions are increased  - both help increase heat production  Temperature control is an example of Negative Feedback Control