Topic 5- Homeostasis and response Flashcards
What does a receptor do
the receptor detects a stimulus
what does the coordination centre do
the coordination centre receives and processes the information then organises a response
what does the effector do
the effector produces the response which counteracts the change and restores it .
what is the nervous system
the receptors detect the stimulus receptors like taste , the receptors can form part of larger organs - eye is covered by light receptor cells . effectors respond to nervous impulses and bring about a change , muscles and glands are known as effectors . muscles contract and glands secrete hormones
reflexes help prevent injuries
reflexes are automatic responses to certain stimuli that don’t involve the conscious part of the brain - for example when a bright light shines on the eye your pupils get smaller
parts of the brain with their functions
cerebral cortex - wrinkly part responsible for memory and intelligence
medulla- controls unconscious activity
cerebellum - responsible for muscle coordination
how does the eye change to focus on near objects
the ciliary muscles contract and suspensory ligaments slacks
this increases the amount by which it refracts light
how does the eye change to view far away objects
the ciliary muscles relax and the suspensory ligaments tighten so it refracts light by a small amount
what contact lens would you need if you are short / long sited
long sited - convex
short sited - concave lens
what happens when your too hot
sweat is produced in glands and evaporates from the skin to the environment , the blood vessels supply to the skin dilate so more blood flows to the surface , called vasodilation
what happens when your too cold
hairs stand up to trap an insulating layer of air
no sweat is produced
capillaries constrict the blood supply
called vasoconstriction
compare hormones and nerves
nerves : very fast , act for a short time , ac tin a precise area
Hormones : slower , act for a long time , act in a more general way
what are removed from urine by the kidney
urea , ions and water
what hormone controls water levels
ADH
Describe the four stages of the menstrual cycle
1) the uterus lining breaks down
2) the uterus lining rebuilds into a spongy layer of blood ready to receive a fertilised egg
3) an egg develop and is release from the ovaries
4) the wall is then maintained
