L3.1 Endocrinology Flashcards
what is the endocrine system
The endocrine system acts to integrate all the functions of the various physiological systems to allow the body to function as a whole.
what are the functions of the endocrine system
regulate metabolism, water and electrolyte balance; allow body to cope with stress; regulate growth; control reproduction; regulate circulation and red blood cell production; control digestion and absorption of food
hydrophilic vs lipophilic
Hydrophilic: ______ water; _____ through plasma membrane; _____ onset, _____-acting
Lipophilic: ____ water; ______ across the plasma membrane; _____ onset, _____-acting
Hydrophilic: LIKES water; CAN’T GET through plasma membrane; FAST onset, SHORT-acting
Lipophilic: HATES water; CAN DIFFUSE across the plasma membrane; SLOWER onset, LONGER-acting
peptides are ______ hormones
peptides are HYDROPHILIC hormones
steriods are made from ______
steriods are made from CHOLESTEROL
lipophilic hormones are ________
lipophilic hormones are FAT SOLUBLE
what are the 2 control pathways for secretion
central regulation and direct regulation
describe central regulation
controlled by the brain; affected by negative feedback loops, neuroendocrine reflexes, rhythms (e.g. diurnal); can be fast, slow or long-term responses
describe direct regulation
endocrine cells respond directly to changes in ECF (especially plasma) levels of substances (e.g. glucose, calcium); very rapid response to critical needs
what is target cell responsiveness and the types
• Amplification of hormones effects via second messenger cascade
• Variations in receptor expression on target cell- a cell must have functional receptors specific for the hormone to be able to responds
o Number and type of cell receptors can vary by down-regulation or up-regulation
• Permissive, synergism and antagonism
o Presence or absence of one hormone can influence effects of another through receptor regulation, activation or inactivation
o Permissive: for hormone A to work, hormone B must be present (permits it to work = allow it or not)
o Synergism: one hormone will increase the activity of the other (hormone A present, hormone B will work 2x as well)
o Antagonism: they work opposite to one another (hormone A is present, hormone B won’t work)
in centrally controlled pathways, hormone regulation may be:
a. in response to endocrine cells directly detecting changes in a substance in the plasma
b. affected by negative-feedback loops
c. very rapid responses to critical needs
B (affected by negative-feedback loops)
what are the two groups of anterior pituitary hormones?
- ‘trophic’ hormones (promotes release of another hormone) control activity another endocrine gland – ACTH, TSH, LH and FSH
- Hormones which have a direct effect in their own right – prolactin and growth hormone
what are the hormones of the anterior pituitary
Thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), growth hormone (GH), prolactin, luteinising hormone (LH), follicle-stimulation hormone (FSH)
What happens to hormone secretion when pituitary stalk is sectioned? i.e. hypothalamo-pituitary disconnection
Hormones decrease in all levels except for prolactin = normally the hormones that decreased would be under stimulatory control (something that releases them) but prolactin is under inhibitory control = normally you produce lots of prolactin and its suppressed by dopamine and normally you don’t produce much of the others except when releasing a hormone that triggers their release
