co-ordination and response Flashcards
what happens in vasoconstriction?
- muscle cells in the walls of the arterioles contract
- causes constriction of blood vessels
- less blood flows through capillaries in the skin
- less heat can be lost by radiation
- skin appears pale
what happens in vasodilation?
- muscle cells in the walls of the arterioles relax
- causes dilation of blood vessels
- more blood flows through capillaries in the skin
- more heat can be lost by radiation
- skin appears red
what do reflex arcs do?
- control reflex reactions
- make fast, automatic responses
- stop serious damage
what does homeostasis allow animals to do?
control the internal environment of their bodies
what does homeostasis do?
keeps conditions constant
what is controlled in homeostasis
- water content
- body temperature
where is adrenaline made and what are the effects?
- made in the adrenal glands
- makes the heart beat faster
where is insulin made and what are the effects?
- made in the pancreas
- causes liver + muscles to take up glucose (to keep blood glucose levels normal)
where is testosterone made and what are the effects?
- made in the testes
- controls development of male sex organs
where is progesterone made and what are the effects?
- made in the ovaries
- maintains the lining of the uterus
where is oestrogen made and what are the effects?
- made in the ovaries
- controls development of female sex organs and causes uterus lining to get thick and spongy
what is thermoregulation?
the ability to control body temperature
what is our average body temperature?
37ºc
what are the positive of maintaining are body temperature ?
it allows humans to be active in a range of external activities
how do we conserve heat in the cold?
wear more clothes
how do we adapt in the heat?
drink lots of water
what is the CNS made of?
the brain and spinal cord
what do nerves do in the CNS?
branch out of the brain and spinal cord to reach all parts of the body
what does the nervous system have?
- fast responses
- short lasting
- nerve cells involved
- electrical impulses that go along nerves
what does the hormonal system have?
- slow responses
- long lasting
- glandular cells involved (make hormones)
- hormones transported in the blood
what are some sense organs in the nervous system?
- eyes
- nose
- ears
- tongue
- skin
what does a co-ordinated response require?
- a stimulus
- a receptor
- an effector
what is an example of a response?
sweating
what do cone cells in the retina do?
detect colour
what do rod cells in the retina do?
detect low levels of light
what does the cornea do?
refract light so it passes through the pupil
what does the lens do?
focuses light on the retina
what does changing shape allow the lens to do?
focus on any objects
what happens in the eye to focus on close objects?
- ciliary muscle contracts
- suspensory ligaments go loose
- lens becomes round in shape
what happens in the eye to focus on distant objects?
- ciliary muscle relaxes
- suspensory ligaments go tight
- lens is stretched to become thinner
