Hormones and Homeostasis Flashcards
Define the term hormone; give two examples
A chemical messenger that moves to target organs in the blood plasma, e.g. adrenaline, ADH, oestrogen, testosterone, FSH, LH etc.
Describe the role of insulin after a meal
Insulin released from pancreas; stimulates conversion of glucose to glycogen (stored in muscle/liver); blood sugar level decreases
Describe the role of adrenaline in the body
Released from adrenal glands; increases heart rate and breathing rate; stimulates conversion of glycogen to glucose; diverts blood flow to muscles and away from digestive system; dilates pupils; increases clarity of thinking etc.
Describe the role of testosterone
Released from testes; stimulates development of secondary sexual characteristics in males
Describe the role of oestrogen
Released from ovaries; stimulates development of secondary sexual characteristics in females; repairs uterus lining after menstruation
Describe the role of progesterone
Released from ovaries; maintains lining of uterus during pregnancy
What common structure releases ADH, FSH and LH?
Pituitary gland
Define the term homeostasis
Maintenance of a constant internal environment
Give two examples of homeostasis in the human body
Control of body water levels, control of core body temperature, control of blood glucose levels
Describe what is meant by the term vasodilation
Arterioles near the surface of the skin widen; more blood flows near the surface of the skin; more heat lost by radiation
Describe what is meant by the term vasoconstriction
Arterioles near the surface of the skin narrow; less blood flows near the surface of the skin; less heat lost by radiation
Describe two ways, other than vasodilation, that cool the body down when too hot
Sweating (evaporation of water from surface of skin); hairs lie flat (less heat trapped)
Describe two ways, other than vasoconstriction, that keep the body warm when too cold
Shivering (rapid muscle contractions to release heat by respiration); hairs stand on end (trap more heat)
What part of the brain detects changes in body temperature and water levels?
Hypothalamus