PH1124 - Reproductive hormones Flashcards
what is a hormone? (2)
- chemical substance produced by ductless glands within the endocrine system
- often then secreted directly into bloodstream
what molecule hormones mostly derived from?
- most hormones derived from cholesterol
what are the physiological functions of hormones? (6)
- reproductive cycle; lactation
- growth and development
- metabolism
- digestion
- sleep
- stress and mood (brain)
- reproductive cycle; lactation
- growth and development
- metabolism
- digestion
- sleep
- stress and mood (brain)
- are synthesized and secreted at different levels throughout a person’s lifetime
- increasing at puberty and normally decreasing with old age
- feedback mechanisms regulate these hormones
what are the main modes of action for hormones? (3)
- endocrine action
- paracrine action
- autocrine action
what is the endocrine action of hormones? (2).
- hormones are secreted from a secreting cell in the ductless gland directly into the circulatory system
- they act on distant cells/organs via their target receptors
what is the paracrine action of hormones?
- hormones are secreted and then diffuse through the interstitial spaces to act on nearby target cells
what is the autocrine action of hormones?
- hormones act on the same cell that secreted them via their receptors
what is the endocrine system? (2)
- collection of glands located throughout the body that manufacture and secrete hormones to regulate physiological functions
- generally act in a paracrine or endocrine manner
what are the major endocrine glands? (4)
- adrenal gland
- hypothalamuc
- ovaries and testes
- pituitary gland
what are the general classes of hormones derived from different building blocks? (3)
- hormones derived from amino acids
- protein and peptide hormones
- hormones derived from lipids
what is the structure of cholesterol? (3)
- 3 cyclohexane rings (A to C)
- 1 cyclopentane ring (D)
- large 6C hydrocarbon side chain (C22 to C27)
what is cholesterol the precursor for the biosynthesis of? (4)
- vitamin D
- bile acid; lipid digestion
- steroid hormones; adrenal steroids, glucocorticoids, mineralocorticoids
- sex steroid hormones
where are reproductive steroid hormones mainly produced? (2)
- produced mainly by the gonads (ovaries or testes)
- some production by placenta and adrenal glands
what are reproductive hormones soluble in? (3)
- they are water-insoluble but are lipid soluble
- can easily move across the plasma membrane but not stored in the body
- bound to the carrier steroid hormone-binding globulin
(SHBG) during transport in the bloodstream
what are the classes of reproductive steroid hormones? (3)
- oestrogens
- androgens
- progestogens