endocrine system Flashcards
what is the function of an endocrine gland?
secretes hormones into the bloodstream
what is a hormone?
a chemical messenger that regulates the activity of other body cells
- slow messenger
- requires blood supply
each hormone will have a ______________ and an ___________ (_____________) on that ______________
target, effect (function), target
what cells respond to it (have receptors for it)
targets
how do they respond to it (what happens when those cells come in contact with the hormone)
function
what constantly adjusts hormone levels?
feedback loops
- a stimulus causes an endocrine organ to release hormones
- the hormone helps bring the body back to homeostasis
- once homeostasis is achieved, the hormone release stops
negative feedback loop
all endocrine glands in the body
endocrine system
what oversees the endocrine system?
hypothalamus
what three ways does the hypothalamus exert control over the endocrine system?
- produces “releasing” (and some inhibiting) hormones that regulate the anterior pituitary (middle management)
- produces hormones that are stored in the posterior pituitary
- oversees the autonomic nervous system
what connects the hypothalamus to the pituitary gland?
infundibulum
what is the bony part where the pituitary gland sits?
sella turcia
what are the divisions of the pituitary gland?
anterior and posterior
axons from hypothalamus cells
stores two hormones produced by hypothalamus
posterior pituitary
what two hormones does the posterior pituitary secrete?
oxytocin (OT) and antidiuretic hormone (ADH)
what is the target of oxytocin (OT)?
reproductive organs
what are the functions of oxytocin (OT)?
stimulate smooth muscle contraction in reproductive organs (especially uterine)
- stimulate breastmilk release
what is the target of the antidiuretic hormone (ADH)?
kidneys (and blood vessels)
what is the function of the antidiuretic hormone (ADH)?
inhibits urine formation/promotes water reabsorption
where are OT and ADH produced?
hypothalamus
where are OT and ADH released and stored?
posterior pituitary
controlled by the hypothalamus via regulatory hormones
anterior pituitary
what are the anterior pituitary hormones?
thyroid stimulating hormone (TSH), prolactin (PRL), adrenocorticotropic hormone (ACTH), growth hormone (GH), follicle stimulating hormone (FSH), and luteinizing hormone (LH)
what is the target of thyroid stimulating hormone (TSH)?
thyroid gland
what is the function of thyroid stimulating hormone (TSH)?
stimulates thyroid to produce/release its own hormones
what is the target of prolactin (PRL)?
mammary glands
what is the function of prolactin (PRL)?
stimulates breastmilk production
what is the target of adrenocorticotropic hormone (ACTH)?
adrenal cortex
what is the function of the adrenocorticotropic hormone (ACTH)?
stimulates adrenal cortex to release its hormones
what is the target of growth hormone (GH)?
most body cells, but especially bone and skeletal muscle
what is the function of growth hormone (GH)?
stimulates growth
what is the target of follicle stimulating hormone (FSH)?
ovaries/testes
what is the target of the luteinizing hormone (LH)?
ovaries/testes
what is the location of the thyroid gland?
anterior to trachea and inferior to larynx
what two hormones does the thyroid gland produce?
thyroid hormone (TH) and calcitonin
stimulated by thyroid stimulating hormone (TSH)
produced by follicle cells
thyroid hormone (TH)
what is the target of thyroid hormone (TH)?
virtually all cells of the body
what is the function of thyroid hormone (TH)?
increase metabolism (and thus, heat production)
stimulated by high calcium levels in the blood
produced by parafollicular cells
calcitonin
what is the target of calcitonin?
bone
what is the function of calcitonin?
encourages deposition of calcium from bloodstream into bone tissue, so it lowers blood calcium levels by encouraging osteoblasts
secrete bone matrix
osteoblasts
four tiny oval masses on posterior thyroid
parathyroid glands
what hormone is secreted by the parathyroid glands?
parathyroid hormone (PTH)
what is the target of parathyroid hormone?
bone
what is the function of parathryoid hormone?
encourages uptake of calcium into bloodstream from bone, so it raises blood calcium levels by encouraging osteoclasts
stimulated by low levels of calcium in blood
parathyroid hormone (PTH)
what hormone is secreted when blood calcium levels are high?
calcitonin
what hormone is secreted when blood calcium levels are low?
parathyroid hormone
what gland secretes calcitonin?
thyroid gland
what gland secretes parathyroid hormone?
parathyroid gland
what is the end effect of blood calcium levels with calcitonin?
lowered
what is the end effect of blood calcium levels with parathyroid hormone?
raised
where are the adrenal glands located?
ontop of the kidneys
what does the adrenal cortex do?
releases corticosteroids in response to ACTH
what are the three corticosteroids?
mineralcorticoids (salt)
glucocorticoids (sugar)
androgens (sex)
controls balance of sodium and potassium in body fluids
mineralcorticoids
stimulates metabolism of gluocose
gluocorticoids
small amount of these hormones are secreted
androgens
stimulated by the autonomic (sympathetic) nervous system (4th pathway - preganglionic sympathetic pathway)
adrenal medulla
what is secreted by the adrenal medulla?
epinephrine and norepinephrine
what do epinephrine and norepinephine do?
work with sympathetic division of ANS to stimulate fight-or-flight response
true or false, pancreas has both endocrine and exocrine functions
true
what do pancreatic islets produce?
hormones
what hormones are secreted by the pancreas?
insulin and glucagon
what is the function of insulin?
lowers blood sugar (glucose) levels
- enhances cells to pick up glucose
- helps convert some glucose into glycogen (a carbohydrate)
what is the function of glucagon?
raises blood sugar levels
- breaks down glycogen into glucose
what hormone is secreted when blood glucose levels are high?
insulin
what hormone is secreted when blood glucose levels are low?
glucagon
what gland is insulin and glucagon secreted from?
pancreas
what is the end effect of insulin on blood glucose levels?
lowers
what is the end effect of glucagon on blood sugar levels?
raises
melatonin (circadian rhythm)
pineal
hormones to stimulate and promote growth of t-lymphocytes
thymus
hormones related to various functions of these organs
kidney, heart, GI tract
what do ovaries produce?
estrogen and progesterone
what do testes produce?
androgens (especially testosterone)
