Structure and Function of the Brain
The Brain
- An adult human brain contains approximately 86 billion neurons.
- It is responsible for processing all changes in the internal and external environment.
- The advantage of the brain as a central location for all communication is that it can happen much faster than if there were control centres distributed throughout the body.
Gross Structure
- Cerebrum - controls voluntary actions such as learning, memory, personality, conscious thought.
- Cerebellum - controls unconscious functions such as posture, balance, and non-voluntary movement.
- Medulla Oblongata - used in autonomic control, such as heart and breathing rate.
- Hypothalamus - regulatory centre for temperature and osmoregulation of blood.
- Pituitary Gland - stores and releases many hormones vital for the regulation of many bodily functions.
Cerebrum
- Receives information, interprets it, and then sends an impulse along motor neurons to effector organs to produce a response.
- Responsible for controlling all conscious responses and some involuntary responses.
- Many folds in the cerebrum mean there is increased surface area, and therefore increased capacity for activity.
- Each hemisphere controls the opposite side of the body.
- The cerebrum can be divided into four lobes.
- Each sensory area in each hemisphere receives information from receptor cells in sense organs.
- Sensory areas vary in size depending on the number of receptor cells in the sense organ.
- This information is then passed on to other areas in the brain called associate areas for analysis and reaction.
- Information from associate areas is then sent to motor areas, which transmit impulses down motor neurones to effectors.
- This area is concerned with muscular movement, posture and balance,
- It does not initiate, but coordinate.
- This means damage to the cerebellum can lead to jerky and uncoordinated movement.
- Contains many important regulatory centres for autonomic nervous system.
- Controls unconscious and reflex actions.
- Main controlling region for the autonomic nervous system - with a centre for both sympathetic and parasympathetic systems.
- Controls complex behaviour patterns such as feeding, sleeping and aggression.
- Monitors the composition of blood plasma.
- Produces hormones.
- Controls most of the glands in the body, and has two sections.
- Anterior Pituitary Gland - produces 6 hormones including FSH which is involved in reproduction and growth.
- Posterior Pituitary Gland - stores and releases hormones produced by the hypothalamus such as ADH involved in urine production.