Chapter B10-B11 Flashcards
Homeostasis
Homeostasis is defined as the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external change.
Homeostasis in other words is when your body adapts in different conditions.
How is homeostasis co-ordinated and controlled?
- Cells called receptors: these cells detect changes inside / outside the body.
- Coordination centres (brain,spinal cord,pancreas): receive information, process it and organise a response.
- Effectors: produce the response to the change
Key points - Homeostasis:
. Homeostasis is important for maintaining optimal conditions for enzyme action and all cell functions.
. In the human body homeostasis includes control of blood glucose concentration, body temperature and water levels
. All control systems include receptors, coordination centres, and effectors.
Nervous system
The nervous system consists of:
. The central nervous system (CNS) - the brain and spinal cord
. The peripheral nervous system - nerve cells that carry information to or from the CNS
How the nervous system works
The body is particularly sensitive to changes in the world around you. Any changes (known as stimuli) are picked up by cells called receptors.
Once a sensory receptor detects a stimulus, the information is sent as an electrical impulse that passes along special cells called neurones. These are usually found in bundles of hundreds or even thousands of neurones known as nerves.
The impulse travels along the neurone until it reaches the CNS . The CNS is made up of the brain and spinal cord. The cells that carry impulses from your sense organs to your CNS are called sensory neurones.
Your brain gets huge amounts of information from all the sensory receptors in your body. It coordinates the response to the information, and sends impulses out along the special cells. These cells, called motor neurones carry information from the CNS the the rest of the body. They carry impulses to make the right bits of your body - the effectors - respond.
Effectors may be muscles or glands. Your muscles respond to the arrival of impulses by contracting. Your glands respond by releasing (secreting) chemical substances. For example, your salivary glands produce and release extra saliva when you smell food cooking, and your pancreas releases the hormone insulin when your blood level sugars go up after a meal.
Summed up how the nervous system works:
Stimulus –> receptor –> coordinator (CNS) –> effector
What the nervous system does
The nervous system enables you to react with your surroundings and coordinate your behaviour.
Key points - nervous system:
. Cells called receptors detect stimuli (changes in the environment)
. The nervous system uses electrical impulses to enable your to react quickly to your surroundings and coordinate your behaviour.
