S-Cool Revision Summary
S-Cool Revision Summary
The nervous system controls all body functions.
It receives information from inside and outside the body.
The organs of the body that receive such information are known as receptor organs.
The nervous system has three main parts:
The spinal cord
The brain is the control centre for every activity of the body.
It is made up of nerve cells and fibres and carries messages to and from all parts of the body.
Nerves are thread-like substances made up of a large number of neurones, which are enclosed in an outer coat.
Neurones consist of three parts:
nucleus - the main cell body
dendrites - pick up and receive messages or impulses
axons - transmit messages or impulses
Neurones can be divided into two types:
Sensory neurones carry information to the brain and central nervous system.
Motor neurones carry information from the brain or the central nervous system to other parts of the body.
Sensory or Receptor Organs
There are three types of receptor or sense organs.
Exteroceptors. Interoceptors. Proprioceptors.
Many of the body's activities are controlled automatically.
Actions such as breathing and digestion occur without us thinking about them.
Each organ is provided with two sets of nerves that work in opposing ways. These are known as sympathetic and parasympathetic nerves.
There are two types of reflex responses.
There are reflex actions that are rapid responses to a stimulus by one or more organs.
There are also conditioned reflexes.
The major difference between reflex actions and consciously thought out actions is the speed of the action.
A reflex response bi-passes the brain and goes via the central nervous system.
The brain can control the skeletal muscles.
It sends a message or impulse to the appropriate muscles to contract in a certain way.
When performing a movement, other factors become important too.
Information from senses + How shot should be played = Message sent to muscles
The more experience the player has, the more able the player is to interpret the information from the senses.
Most sports require athletes to react quickly to situations. This reaction time is the time taken to respond to a stimulus.
Movement time is the speed and accuracy of the muscle action. The time taken in responding to a situation can be equated:
Response time = Reaction time + Movement time
Not all co-ordination and control of the body is carried out by the nervous system. There is a system of control that uses chemicals in its mechanism.
This system is called the endocrine system.
The endocrine system is made up of a series of hormone glands that produce hormones.
Hormones are the chemical messengers of the body.
The hormone glands produce and release their own hormone that affects particular organs of the body.
The bloodstream receives the hormones directly from the glands and carries them to their particular organ.
The endocrine glands include the pituitary gland, the thyroid gland, the pancreas, the ovaries - in females, the testes - in males and the adrenal glands.
The adrenal gland plays a significant part in the preparation for a sporting activity, secreting a hormone called adrenalin.
As soon as adrenalin is secreted into the bloodstream the body responds by:
using up more oxygen
releasing more energy
increasing the rate of breathing
increasing the heart rate
diverting blood away from areas such as the digestive system towards the muscles
The body is then prepared for instant action.