The human endocrine system Flashcards
what is a hormone?
what is it produced by?
a chemical substance
a gland
what are hormones carried in?
the bloodstream
what does a hormone do?
alters the activity of specific target organs
what happens to the hormone once it has been used up?
it is destroyed by the liver
what is the difference between the nervous and hormonal system in terms of ‘Type of signal’:
-Electrical (chemical at synapses)
-Chemical
what is the difference between the nervous and hormonal system in terms of ‘Transmission of signal’:
-By nerve cells (neurones)
-By the bloodstream
what is the difference between the nervous and hormonal system in terms of ‘Effectors’:
Muscles or glands Target cells in particular organs
what is the difference between the nervous and hormonal system in terms of ‘Type of response’:
-Muscle contraction or secretion
-Chemical change
what is the difference between the nervous and hormonal system in terms of ‘Speed of response’:
-Very rapid
-Slower
what is the difference between the nervous and hormonal system in terms of ‘Duration of response’:
-Short (until nerve impulses stop)
-Long (until hormone is broken down)
what are the 6 glands which secrete hormones?
-pituitary gland
-thyroid gland
-pancreas
-adrenal glands
-ovaries
-testes
what hormone does the pituitary gland produce?
ADH (anti-diuretic hormone)
what hormone does the thyroid gland produce?
thyroxine
what hormone does the pancreas produce?
insulin
what hormone do the adrenal glands produce?
adrenaline
what hormones do the ovaries produce?
oestrogen
what hormones do the testes produce?
testosterone
what is the target organ of ADH?
the kidneys
what is the role and effect of ADH? (2)
-Controlling the water content of the blood
-Increases reabsorption of water by the collecting ducts
what are the target organs of adrenaline?
organs in the respiratory and circulatory systems
what is the role and effect of adrenaline? (2)
-Preparation for ‘fight or flight’
-Increases breathing rate, heart rate, flow of blood to muscles, conversion of glycogen to glucose
what is the target organ of insulin?
the liver
what is the role and effect of insulin? (2)
-Controlling blood glucose levels
-Increases conversion of glucose into glycogen for storage
what does the hypothalamus do? (2)
-detects changes in hormone levels
-will release hormones which control the pituitary gland or other organs.
what is homeostasis?
the maintenance of constant internal conditions in an organism.
which conditions must be kept constant within animals? (3)
-water concentration
-temperature
-glucose concentration
what does a negative feedback control system do?
responds when conditions change from the ideal or set point and returns conditions to this set point
what generally happens with negative feedback is conditions fall or rise? (2)
if the level of something rises, control systems reduce it again
if the level of something falls, control systems raise it again
what is body temperature controlled by?
the hypothalamus
what happens when your body gets too hot or too cold? (2)
-if your body gets too hot, your body begins to sweat, which reduces body temperature.
-if the body gets too cold, your body begins to shiver to raise body temperature.
