B10 - Nervous System Flashcards
What is homeostasis?
Homeostasis is the regulation of internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.
Name all the control systems
Receptors, coordination centres, and effectors.
What are receptors? What are the changes called?
Cells that detect changes in the internal or external environment. The changes are called stimuli
What are coordination centres?
Areas that receive and process the information from the receptors. They send out signals and coordinate the response of the body. They include the brain, spinal cord and pancreas.
What are effectors?
Muscles or glands that bring about responses to the stimulus that has been received. These responses restore conditions in the body to the optimum levels.
How is information passed receptor to the coordination centres?
Information is sent as an electrical impulse that passes along special cells called neurones. These can usually be found in bundles called nerves.
What are motor neurones?
Cells that carry information from the CNS to the rest of the body. They carry impulses to the effectors.
What are reflex actions?
Automatic and rapid and do not involve the conscious parts of the brain.
What do reflex actions do?
Control everyday bodily function, such as breathing and digestion and help to avoid danger.
What are the different parts of the brain?
Cerebral cortex, the cerebellum and the medulla.
What is in the retina?
Receptors in tne retina that are sensitive to lignt intensity and colour.
What does the optic nerve do?
Carries impulses from the retina to the brain.
What is accommodation?
The process of changing the shape of the lens of the eye tp focus near or distant objects.
How does the eye focus on close objects?
The ciliary muscles contract, the suspensory ligaments loosen and the lens becomes thicker so it can refract light rays strongly.
How does the eye focus on distant objects?
Ciliary muscles relax, suspensory ligaments are tight and the lens is thin so it refracts light slightly
