B10- The Human Nervous System Flashcards
What is homeostasis?
The regulation of the internal conditions of cells to maintain optimum conditions for functioning, in response to internal and external changes.
Why is homeostasis important?
For maintaining optimal conditions for enzyme action,
What internal conditions are controlled?
Body temp Water content of the body Blood glucose concentration Salts pH Ions
What is automatic control?
Involves nervous responses in your nervous system and chemical responses in your hormone system.
What are receptors?
Cells that detect changes in internal or external environment.
What are coordination centres?
Receives info from receptors, process the info and coordinate responses in the body.
What are effectors?
Muscles or glands that bring about responses to the stimulus that has been received
What does the nervous system do?
Send electrical impulses to enable you to react quickly to your surroundings and coordinate your behaviour
What do receptors detect?
Stimuli (changes in the environment)
How does the nervous system work?
Impulses from receptors pass along sensory neurones to the brain or spinal cord. The brain then coordinates the response and impulses are sent along motor neurones from the brain to the effector organs.
What are reflex actions?
These are automatic and rapid and do not involve the consciousness or the brain.
What is the route of reflex actions?
Receptors Sensory neurone Spinal cord Motor neurone Effector
What do reflex actions control?
Everyday bodily functions eg breathing and digesting and help to avoid danger.
What is the brain made up of?
Billions of interconnected neurones that control complex behaviours.
What is the cerebral cortex?
Concerned with consciousness, intelligence, memory and language
What is the cerebellum?
Concerned with coordinating muscular activity and balance.
What is the medulla?
Concerned with unconscious activities such as controlling the heartbeat, the movements of the gut and breathing
What is electrically stimulating the brain?
Removing the top of the skull, scientists can stimulate different areas and see what effect this has. You could experience hunger, anger or fear by stimulating the brain.
What are MRI scans?
You can understand how the brain works by taking photos of the brain. If there is a tumour an MRI can show exactly which area of the brain is affected.
What are problems with the brain?
It is difficult to treat different brain problems. Drugs may not reach the brain through the membrane and surgery is difficult as we do not know fully what each area of the brain does.
What is accommodation?
Changing the lens shape to focus on near or distant objects.
To focus on near object:
The ciliary muscles contract.
Radial muscles relax.
Pupils constricts.
To focus on near objects:
Ciliary muscles relax
Radial muscles contract
Pupils dilate
What are the use of contact lenses?
Placed on the surface of the eye and are the same as glasses but are less visible and easier to use.
What is laser eye surgery?
Lasers treat myopia by reducing the thickness of the cornea so refracts less light. Hyperopia lasers change the curve of the cornea.
What are replacement lenses?
Add another lens inside the eye to correct the visual defect permanently.
