Flashcards in Homeostasis and response Deck (49)
What is homeostasis?
Maintaining a stable internal environment controlled by automatic nervous and hormonal control systems.
What is negative feedback?
A mechanism that keeps internal conditions stable. When a level of something (eg. water, blood sugar, temperature) gets too high or too low, your body uses negative feedback to bring it back to the normal level.
What does the nervous system do?
Detects and reacts to stimuli
What are stimuli?
Changes in environment
What is the nervous system made up of?
Central Nervous System CNS (brain and spinal cord)
What are receptors?
The cells that detect stimuli.
They can form part of larger organisms.
What are effectors?
Effectors respond to nervous impulses and bring about a change.
They're either muscles or glands.
What are synapses?
The connection between two neurones.
What are reflexes?
Rapid, automatic responses to certain stimuli that do not require the conscious part of the brain.
What is the reflex arc?
What is the function of the cerebral cortex?
The part of the brain responsible for consciousness, memory, intelligence and language.
What is the function of the medulla?
The part of the brain that controls unconscious activities eg. breathing and heartbeat
What is the function of the cerebellum?
The part of the brain responsible for muscle coordination.
How do scientists study the brain?
-Studying patients with brain damage
-Electrically stimulating the brain
What are the disadvantages of studying the brain?
It is difficult.
There is a risk of physical damage or increased problems involving the brain.
What is the sclera?
Tough, supporting wall of the eye
What is the cornea?
The transparent outer layer at the front of the eye which refracts light into the eye.
What is the iris?
The coloured part of the eye that contains muscles which control the diameter of the pupil and therefore how much light enters the eye.
What is the pupil?
Hole in the middle of the eye which light enters through
What is the lens?
The part of the eye that focuses the light.
What is the retina?
The part of the eye that contains receptor cells sensitive to light intensity and colour.
What is the function of the ciliary muscles and suspensory muscles?
Control the shape of the lens
What is the function of the optic nerve?
Carries impulses from the receptors on the retina of the eye to the brain
What happens to the eye in bright light?
Pupil constricts (goes smaller)
Circular muscles contract
Radial muscles relax
What happens to the eye in dim light?
Pupil dilates (gets bigger)
Circular muscles relax
Radial muscles contract
What happens to the eye to look at near objects?
Ciliary muscles contract which slacken the suspensory ligaments
Lens becomes fat (more curved)
Increases amount by which it refracts light
What happens to the eye to look at distant objects?
Ciliary muscles relax which allow the suspensory ligaments to pull tight
Lens becomes thins (less curved)
Refracts light by smaller amount
What is hyperopia?
Being unable to focus on near objects
What is myopia?
Being unable to focus on far objects