Endocrine System Flashcards
how can we categorize endocrine organs
into 2 types: primary organs/glands and secondary organs
what are the secondary endocrine organs
heart, stomach, kidney, liver, skin, small intestine
what are the primary endocrine structures
hypothalamus; pituitary, pineal, thyroid, parathyroid, adrenal glands, thymus, pancreas, gonads
what is the anterior lobe derived from
epithelial tissue
what is the posterior lobe derived from
neural tissue
describe the neural connection b/w hypothalamus and posterior pituitary gland
posterior lobe has neural tissue with axon terminals of neurons that originate in the hypothalamus
what do the neural endings in the posterior tube secrete
neurohormones (peptide hormones)
provide examples of neural endings in the posterior lobe that secrete neurohormones
- supraoptic nuclei secrete oxytocin
- paraventricular nuclei secrete ADH (antidiuretic hormone)
describe the neurosecretory reflex
neurons release hormones using exocytosis when they receive a signal
what is the function of ADH
- stands for antidiuretic hormone but also called vasopressin
- responsible for water balance and osmolarity (target cells in kidney)
- release stimulated by increase in plasma solute concentration
what is the function of oxytocin
- responsible for uterine contractions and milk release (target cells in uterus and breasts)
- release stimulated by pressure in uterus and sucking from baby
what are tropic hormones; how can they be classfied
- hormones that regulate secretion of other hormones
- stimulating, inhibiting
draw the signalling pathway flow of tropic hormones in hypothalamus
- hypothalamus release tropic hormone
- second tropic hormone released from anterior pituitary gland
- third hormone released from another endocrine gland
- target cells respond
describe the importance of the hypothalamic-pituitary portal system
- provides direct delivery of tropic hormones to target cell in anterior pituitary
- lets tropic hormones to remain more concentrated which has a greater effect on hormone release
draw out the feedback loops that regulate multistep pathways of hormone release
….
draw out the regulation of cortisol release, label the tropic hormone(s) and explain why this is long loop negative feedback
….
describe the pineal gland
- glandular tissue in brain
- secretes melatonin
what is the importance of melatonin
- circadian rhythms (maybe)
- timing of seasonal processes in mammals
what are the hormones in the thyroid gland and what do they do
- tetraiodothyronine (T4)
- triiodothyronine (T3)
- regulate metabolism
- calcitonin
- regulates calcium levels in blood
what hormone is released by the parathyroid glands and what does it do
- parathyroid hormone (PTH)
- regulates calcium levels in blood by acting on bones, kidneys, intestines to increase blood calcium
what hormone is released by the thymus gland and what does it do
- thymosin
- important for immunity
- maturation of T lymphocytes
what are the layers of the adrenal glands top to bottom
capsule, zona glomerulosa, zone fasciculuta, zona reticularis, adrenal medulla
what is an adrenocorticoid
- hormones secreted collectively from adrenal cortex
- all are steroid hormones
- different types
what are three types of adrenocorticoids
- mineralocorticoids (aldosterone)
- glucocorticoids (cortisol)
- sex hormones (androgens)
where are mineralocorticoids secreted from and what do they do
- zona glomerulosa
- regulates sodium and potassium levels
where are glucocorticoids secreted from and what do they do
- zona fasciculata and reticularis
- regulates body’s response to stress and also regulates metabolism
where are sex hormones released from
- zona fasciculata and reticularis
- regulate reproductive function
describe the adrenal medulla
- contains chromaffin cells
- secretes catecholamines (80% epinephrine; 20% norepinephrine; less than 1% dopamine)
- neurally controlled
what are the components of the exocrine pancreas
- acinar cells
- duct cells
what are the components of the endocrine pancreas
- exocrine pancreas layer (islets of Langerhans make up whole)
- alpha cell (glucagon)
- beta cells (insulin)
- delta cell (somatostatin)
- F cell (pancreatic polypeptide)
describe the gonads
- ovaries and testes
- have endocrine and nonendocrine functions
describe endocrine functions of the gonads
- male: secreting androgens, testosterone, androstenedione
- female: estrodiol, progesterone
describe nonendocrine functions of the gonads
ova and sperm production
what does the concentration of free hormone in blood depend on
- rate of hormone secretion
- amount of hormone bound to plasma proteins
- rate of hormone metabolism
what does rate of hormone secretion depend on
- release of chemical messages by cells at variable rates
- neural and humoral signals influence increase and decrease rate of secretion
- whether its an ongoing process or not
how do neural signals regulate hormone secretion
- directly
- using hypothalamus (w/ tropic hormones); posterior pituitary (w/ ADH and oxytocin); adrenal medulla (w/ epinephrine)
describe hormone actions during stress
neural signals travel to hypothalamus which triggers CRH release, anterior pituitary releases ACTH and adrenal cortex releases cortisol
what are the categories of humoral signals
hormones, ions, metabolites
describe the regulation of blood glucose levels
blood glucose increases which causes insulin release in pancreas beta cells and glucose uptake in all cells through body which decreases blood glucose levels (negative feedback)
describe the regulation of blood potassium levels
blood potassium increases which causes aldosterone release in adrenal cortex and potassium excretion in kidneys which causes blood potassium to go down (negative feedback)
describe hydrophilic hormones
- dissolve in plasma
- EX peptides, catecholamines
describe hydrophobic hormones
- transport in blood bound to carrier proteins
- only free hormones bind to receptors and have ability to be metabolized
- longer half-life
what are examples of abnormal hormone secretion
- hypersecretion
- hyposecretion
describe primary hypersecretion of cortisol
- abnormality in endocrine gland that secretes hormone
- there is excess cortisol secretion which means that there are decreased levels of ACTH and CRH but regulation is inadequate and won’t help to bring cortisol down (negative feedback)
describe secondary hypersecretion of cortisol
- abnormality with endocrine cells of anterior pituitary or hypothalamus which secrete tropic hormone
- EX excess ACTH in ant pit which causes excess cortisol secretion in adrenal gland which also leads to CRH decrease but none of the 2 regulations are enough to bring the ACTH back down
what are the ways a hormone can interact
antagonism, additive effect, synergism, permissiveness
describe antagonism
effects of hormones opposing e/o (glucagon vs insulin)
describe additive effect
net effect equals sum of individual effects
describe synergism
effects of 2 hormones favour e/o but net effect exceeds sum of individual effects
describe permissiveness
one hormone is needed for another to exert its effects (thyroid hormones needed for expression of beta adrenergic receptors in bronchiolar smooth muscle)
