5.2 hormonal communication & glands Flashcards
what is an endocrine gland?
a group of cells secreting hormones directly into the blood stream
give examples of some endocrine glands:
pituitary gland thyroid gland adrenal gland testis pineal gland thymus pancreas ovary
what does the pituitary gland do?
produces growth hormones
the pituitary gland releases the antidiuretic hormone what does this increase?
reabsorption of water in the kidneys
the pituitary gland also releases gondotrophins what do these control the development of?
ovaries and testes
what does the thyroid gland produce?
thyroxine
(thyroid gland) what does thyroxine do?
controls metabolism rate and the rate glucose is used up in respiration, promotes growth
what does the adrenal gland produce?
adrenaline
what does adrenaline (produced by the adrenal gland) do?
increases heart rate, breathing rate and blood sugar levels
what do testes produce?
testosterone
what does testosterone (produced by the testis) do?
control sperm production and secondary sexual characteristics
what does the pineal gland produce?
melatonin
what does melatonin (produced by the pineal gland) do?
affects reproductive development and daily cycles
what does the thymus produce?
thymosin
what does thymosin (produced by the thymus) do?
promotes production and maturation of white blood cells
what does the pancreas produce?
insulin and glucagon
what does insulin (produced by the pancreas) do?
converts excess glucose to glycogen in liver
what does glucagon (produced by the pancreas) do?
converts glycogen back to glucose in the liver
what does the ovary produce?
oestrogen and progesterone
what does oestrogen (produced by the ovary) do?
controls ovulation and secondary sexual characteristics
what does oestrogen and progesterone (produced by the ovary) do?
prepares uterus lining for receiving an embryo
what is an exocrine gland?
a group of cells secreting chemicals through ducts into organs or the surface of the body
give an example of where exocrine glands are found:
in the digestive system
what are hormones?
chemical messengers carrying information from one part of the body to another
what can hormones be?
steroids proteins glycoproteins polypeptides amines tyrosine derivatives
what are tyrosine derivatives?
thyroid hormones and chatecholamines
what are chatecholamines?
stress hormones released by the adrenal medulla important in the fight or flight response
when a gland is stimulated what happens to hormones?
secreted directly into blood stream
what change stimulates a gland?
change in substrate conc.
e.g. insulin released in response to blood glucose conc
hormones can also be released due to the action of what?
another hormone or nerve impulse
once secreted what do hormones travel in?
blood plasma
when hormones diffuse out the blood what do they bind to?
specific receptors on the membrane or cytoplasm of target cells
once bound to receptors what do hormones stimulate?
target cells to produce a response?
why can STEROID hormones pass through the cell membrane?
lipid soluble
where could receptors for STEROID hormones be?
in the cytoplasm or nucleus
what complex do STEROID hormones and receptors form?
hormone receptor complex
what does the hormone receptor complex facilitate or inhibit? (STEROID)
transcription of a specific gene
why can’t non steroid hormones pass through membrane?
not lipid soluble
where are the receptors for non steroid hormones found?
cell surface membrane
when non steroid hormones bind to receptors what do they trigger a cascade of and by what chemicals?
events by second messengers
