Coordination and Response Flashcards
What do receptors do?
Detect stimuli
What do effectors do?
Cells that bring about a response to stimuli
What is in the CNS?
Spine and brain
What does the CNS do?
Coordinate the response to the stimuli
What do synapses do?
Connect neurones
How do synapses work?
The nerve signal is transferred by chemicals called neurotransmitters which diffuse across the gap
These chemicals then set off a new electrical signal in the next neurone
What do reflexes do?
Help prevent injury
How do reflexes work?
The neurones in reflex arcs for through the spinal cord or through an unconscious art of the brain. This makes the effector act faster protecting the body
What does the conjunctiva do?
Lubricates and protects the surface of the eye
What does the sclera do?
Protects the eye
What does the cornea do?
Refracts light into the eye
What does the iris do?
Controls the diameter of the pupil
What does the lens do?
Focuses the light onto the retina
What does the optic nerve do?
Carries impulses to the brain
What is the iris reflex and what does it do?
The iris reflex adjusts for really bright or dim light to protect the eye.
When the light it bright the eye becomes smaller letting less light in
When the light is low the eye becomes larger allowing more light in
What happens when you focus on distant objects?
1) The ciliary muscles relax so the suspensory ligaments pull tight
2) Lens goes flat
3) Refracts light by a smaller amount
What happens when you focus on near objects?
1) Ciliary muscles contract so the suspensory ligaments relax
2) Lens becomes more curved
3) This increases the amount by which it refracts light
What are hormones?
Hormones are chemical messengers that are sent into the blood
Where is adrenaline produced and what does it do?
Adrenal gland, increases the heart rate and blood flo
Where is insulin produced and what does it do?
Pancreas, Stimulates the liver to turn glucose into glycogen for storage
Where is testosterone produced and what does it do?
Testes, promotes male characteristics
Where is progesterone produced and what does it do?
Ovaries, maintains the lining of the uterus
Where is oestrogen produced and what does it do?
Ovaries, controls the menstrual cycle and promotes female characteristics
Where is ADH produced and what does it do?
Pituitary gland, controls water content
Where is FSH and LH produced and what do they do?
Pituitary gland, female sex hormone
What is the difference between a nerve and a hormone?
Nerves are fast, act for a short time and act on a precise area
Hormones are slower, act for a long time and act in a general area
What is homeostasis?
Balancing body functions to maintain a constant internal enviroment
How is water lost from the body?
1) Sweat
2) Breathing
3) Urine
What is the internal body temperature?
37 degrees
What does the body do when you are too hot?
1) Produces sweat - transfers energy from your skin to the environment
2) Blood vessels close to the surface widen - transfers more energy into the surroundings
3) Hairs lie flat
What happens to the body when you are too cold?
1) Little sweat is produced
2) Blood vessels near the surface constrict - transfers less energy to the surroundings
3) You shiver - increases the rate of respiration to warm up the body
4) Hairs stand up - traps an insulating layer of air
Why can smaller organisms cool down quicker?
They have a bigger surface area to volume ratio
Can lose body heat in hot climates easily but they are vulnerable in cold environments
What are auxins?
Growth hormones that control the growth at the tips of shoots and roots
What does it mean when something is positively photrophic?
It grows towards the light
What does it mean when something is negatively phototrophic?
It grows away from the light
What does it mean when something is positively geotrophic?
It will grow away from gravity
What does it mean when something is negatively geotropic?
It grows towards gravity
