Homeostasis

• Regulation of conditions inside our bodies to maintain a stable internal environment . To respond to changes both inside and outside our bodies
• Negative feedback - the effectors respond to counteract the change bringing the levels back to optimum level
• Automatic responses are reflexes
• Reflex arc - sensory neuron, relay neuron, motor neuron
• Long sighted is corrected with convex lens
• Short sightedness is corrected with concave lens
• Hormone - gland that secrets a chemical directly into the blood stream to its target organ
• Auxin - stimulates cell elongation
• Phototropism - plants growth response to light
• Gravitropism - plants growth response to gravity
• Oestrogen - stimulates building of uterine lining , stimulates LH , inhibits FSH
• Progesterone - maintains uterus lining , inhibits LH and FSH
• FSH - makes eggs mature , stimulates ovaries to produce oestrogen
• LH - stimulates release of egg
• bright light - circular muscles contracting , radial muscles relaxing , pupil becomes narrower
• dim light - circular muscles relax , radial muscles relax , pupils become wider
• ciliary muscles & suspensory ligaments - controls shape of the lens
• near objects - ciliary muscles contract , suspensory ligaments relax , lens becomes more curved , increase amount of light refracted
• distant objects - ciliary muscles relax , suspensory ligaments contract , lens becomes thinner / less curved , decrease amount of light refracted
• pituitary gland - ADH
• pancreas - insulin & glucagon
• ovaries - oestrogen
• testes - testosterone
• thyroid - thyroxine
• kidney - vitamin d
• adrenal gland - adrenaline