b5 - homeostasis and response

• coordination centres : brain, pancreas, spinal cord
• coordination centres send instructions to the effectors
• effectors bring about responses to stimuli e.g. glands, muscles
• receptors detect changes in an environment
• coordination centres obtain and process information from the receptors
• receptors detect changes in temperature, glucose concentrations and water levels
• sensory neurone - detects stimulus
• relay neurone - transmits signal from sensory to motor neurone
• motor neurone - transmits impulse to effector
• blood glucose is controlled by the pancreas
• glucose too high -> stored in liver and muscles as glycogen
• glucose too low -> pancreas releases insulin, glucose moved back into cells
• pancreas secretes glucagon so glycogen is converted to glucose and released
• type 1 diabetes : insufficient insulin is produced by the pancreas
• type 1 diabetes treatment - insulin injections
• type 2 diabetes : body cells do not respond to insulin, obesity is a risk factor
• type 2 diabetes treatments : exercise regime, carbohydrate controlled diet
• oestrogen : stimulates ovulation
• testosterone : sperm production
• IVF disadvantages ; risk of multiple births, low success rate, stress
• Oestrogen + Progesterone: maintains uterine lining
• Oestrogen stimulates the release of LH (hormone)
• FSH (hormone) : maturation of an egg in the ovary
• LH: stimulates release of an egg
• the sensory neurone transmits impulses from the receptor to the central nervous system (CNS)
• the motor neurone transmits impulses from the CNS to the effectors
• relay neurones pass the impulses from the sensory neurones to the motor neurones
• the effector can be a muscle or a gland; the role of the effector is to carry out the response
• impulses can only travel in one direction along the neurones
• A synapse is a microscopic gap between two neurones. A chemical called a neurotransmitter diffuses from one side of the synapse to the other
• a reflex arc is simple and contains only three neurones
• the reflex arc allows for a very rapid response to changes in the environment
• reflex actions do not involve the brain controlling the action so are said to be involuntary
• the effector at the end of the reflex arc may be a gland or a muscle
• receptor cells which detect stimuli are found withing sense organs
• ovaries produce oestrogen and progesterone
• pancreas produces glucagon and insulin
• adrenal glands produce adrenaline
• thyroid gland produces thyroxine
• pituitary gland secretes several different hormones into blood