Coordination and Response Flashcards
What is homeostasis?
Homeostasis is the maintenance of a constant internal environment
eg body temperature, blood glucose level, water content
What are receptors?
Receptors detect external stimuli
Eg eyes detect changes in light
What are effectors?
Effectors are cells that bring about a response to stimuli
eg muscle cells
What is a stimulus?
Any change in the internal or external environment
What is negative feedback?
The process by which the body corrects any movement away from the optimum internal conditions.
A change in environment is detected, signalled to other cells and responded to to reverse it
What are hormones?
Chemical messengers
Released into the blood
Slow acting and long lasting
What is the normal blood glucose level?
90mg/100cm3 of blood
What is insulin and what does it do?
Hormone produced by pancreas
Helps control blood sugar levels
Levels too high -> pancreas secretes more insulin -> more glucose is changed to glycogen -> normal levels
What is ADH and what does it do?
Anti-diuretic hormone
Released by pituitary gland
Makes collecting ducts of nephrons more permeable so more water is reabsorbed
Water loss -> more ADH released -> kidney reabsorbs more water -> hydrated
What is vasodilation?
When blood vessels close to the skin’s surface widen.
Increases blood flow, so more thermal energy transfer to surroundings, cooling you down.
What is vasoconstriction?
When blood vessels close to the skin’s surface narrow/constrict.
Reduces blood flow, so less thermal energy transfer to surroundings.
What does skin do when you’re too hot?
Produces sweat, which evaporates transferring energy to surroundings
Vasodilation
Hairs lie flat
What does skin do when you’re too cold?
Produces very little sweat
Vasoconstriction
Hairs stand on end to trap insulating layer of air
What is adrenaline and what does it do?
Secreted by adrenal glands
Makes heart beat faster, so muscle cells receive more glucose and oxygen for respiration
Prepares for ‘fight or flight’
What is testosterone and what does it do?
Hormone produced by the testes
Main male reproductive hormone and stimulates sperm production
Controls secondary sexual characteristics, eg facial hair
What is oestrogen and what does it do?
Hormone produced by the ovaries
Repairs, thickens and maintains the uterus lining. stimulates LH release, stops FSH production
Controls secondary sexual characteristics, eg breast development
What is progesterone and what does it do?
Hormone secreted by ovaries
Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy.
What is LH (lutenising hormone) and what does it do?
Hormone secreted by pituitary gland Stimulates ovulation (egg release) in females and testosterone production in males
What is FSH (follicle stimulating hormone) and what does it do?
Secreted by pituitary gland
Stimulates egg development in ovary and oestrogen secretion in females and sperm production in males
What is the placenta?
Organ responsible for providing oxygen and nutrients to fetus and removing waste substances
Mother and fetus’s blood do not mix, substances diffuse
What does amniotic fluid do?
Acts as a shock absorber, protecting the fetus
