Section 6

Stimulus - Receptor - sensory neurone - CNS (relays neurone relays to motor) - Motor neurone - Effector - Response

Conjuctive - lubricates and protects the surfce of the eye
Scelra - tough layer protects the eye
Cornea - refracts light into the eye, transparent no blood vesssels
Iris - controls how much light enters the eyem controls the diameter of the pupil
Lens - focuses liht onto the retina
optic nerve - carries impulses from the receptors to the brain

Bright light
light receptors detect the bright light - send messsage along a sensory neurone to the brain - travels along the relay neurone - to a motor neurone - tells curcular muscles in the iris to contract - Pupil gets smaller - less light enters

Dim light
light receptors detect the dim light - send messsage along a sensory neurone to the brain - travels along the relay neurone - to a motor neurone - tells radial muscle in the iris to contract - Pupil gets bigger- more light enters

- Ciliary Muscles relax
- Suspensory ligaments tighten
- Lens goes thin
- refracts light by a smaller amount

- Ciliary muscles contract
- Suspensory ligaments loosen/slacken
- Lens becomes fat more curved
- refracts light by greater amount

- unable to focus on distant objects
- happens when cornea or lens bend light too much
- images are brought into focus infront of the retina

- unable to focus on near objects
- happens when cornea or lens don't bend light enough
- images are brought into focus behind the retina

adrenaline - adrenal glands - fight or flight - high rate blood flow, blood sugar level
insulin - pancreas - controls blood sugar level -stimulates liver to turn glucose into glycogen testosterone - Testes - male sex hormone - promotes male secondary sexual characteristics

progesterone - ovaries - supports pregnancy - maintains lining of the uterus
oestrogen - ovaries - female sex hormone - controls menstrual cycle promotes female secondary sexual characteristics

ADH - pituitary gland - controls water content - increases permeability of the kidney tubules
FSH - pituitary gland - female sex hormone - causes egg to mature in the ovary stimulates oestrogen release
LH - pituitary gland - female sex hormone - stimulates release of an egg from an ovary

Nerves: fast message, short time effect, precise area
Hormones: slower message, long time effect, general way

maintenance of a constant internal environment
eg. water content and body temperature

- Lots of sweat produced, when it evaporates it transfers energy from skin to environment
- Blood vessels close to the skin surface widen, allows more blood to follow near the surface - Vasolidation
- More energy is transferred into the surroundings cooling you down
- Hairs lie flat

- Little sweat produced
- Blood vessels near the skin surface constrict - vasoconstriction, less blood flows near the surface, less energy transferred to the surroundings
- Shivering increasing rate f ttranspiration transfers more energy to warm body
- Hair stand to trap an inslating layer of air

Auxins (hormone) control gorwoth of roots and shoots
Promote shoot growth
Inhibit root growth

Shoots positively phototrophic
auxins accumulate on the shaded side of the shoot, making cells grow faster on the shaded side so the shoot bends towards the light
The root is negatively phototrophic
Auxin accumulates on the shaded side
auxins inhibit root growth
root bends downwards

Shoots negatively geotropic
auxins accumulate on the lower side of the shoot, makes cells grow faster on the lower side so the shoot bends towards upwards away from gravity
Roots are positively geotropic
Auxin accumulates on the lower side
auxins inhibit root growth
root bends downwards