B10: The Nervous System Flashcards
What is homeostasis?
The regulation of internal conditions of a cell or organism to maintain optimum conditions for function in response to the internal and external changes
What do all control systems include?
Receptors, a coordination centre and effectors
What are receptors?
Cells which detect stimuli
What is the coordination centre?
Organs that receive and process information from receptors
What are effectors?
Muscles or glands that bring about responses which restore optimum levels
Describe how the nervous system works
Information from receptors passes along neurones as electrical impulses to the CNS, which is the brain and the spinal cord. It coordinates the response of effectors which may be muscles contracting or glands secreting hormones
What is the order of a nervous system response?
Stimuli - receptors - coordination centre - effectors - response
What is interesting about reflex responses?
They are automatic and rapid; they do not involve conscious parts of the brain
How have neuroscientists been able to map the regions of the heart?
Brain damage, MRI scans and electrically stimulating parts of the brain
What is accommodation?
The process of changing eye shape of the lens to focus on near or distant objects
What 3 things happen when focusing on a near object?
Ciliary muscles contract, suspensory ligaments loosen and the lens becomes thicker, refracting light rays strongly
What 3 things happen when focusing on a distant object?
Ciliary muscles relax, suspensory ligaments are pulled tight and the lens becomes thinner, refracting light rays slightly
What is myopia and hyperopia?
Short-sightedness and long-sightedness
What are treatments for eye defects?
Spectacle lenses, soft contact lenses, laser eye surgery and replacement lenses
What does laser eye surgery do?
Changes the shape of the cornea
What doe spectacle lenses do?
They refract light so that they focus on the retina
What is the function of the cerebral cortex?
Conscious behaviour, for example, intelligence, memory and language
What is the function of the cerebellum?
Balance and muscle coordination
What is the function of the medulla?
Unconscious behaviour, for example breathing and heartbeat
What are 3 main reasons treating brain disease is difficult?
Encased by skull, illnesses can emerge and it is complicated, so hard to target medication
Why do we need the cornea?
It causes light to refract
What happens when the eye focuses on bright light?
The pupil is constricted, circular muscles contract and radial muscles relax
Why are reflexes important?
They protect us from harm
