lecture 9: endocrine system Flashcards
what are hormones
chemicals that are released into the blood stream
travel to specific target cells
where are hormones released from
endocrine glands
endocrine cells
what are exocrine glands
excrete things outside the body
like sweat glands
which other system is endocrine system closely related to
nervous system
both systems coordinate and direct activity of body’s cells
what is the main difference between nervous system and endocrine system
communication
nervous system is way faster than endocrine system
most hormones are regulated by what
negative feedback
regulates hormone levels (turn off own production)
allows body to maintain homeostasis
describe the pathway of regulation of pH
low pH in duodenum
S cells of duodenum secrete secretin
target = pancreas = releases bicarbonate
increases pH
secretin release stops
a few hormones are regulated by what
positive feedback
explain example of positive feedback suckling
oxytocin stimulates contraction of smooth muscles in breasts to release milk
suckling = more oxytocin = more milk =
more suckling
what does oxytocin do (childbirth)
stimulates contractions during childbirth
where is oxytocin produced and stored
produced in hypothalamus
stored in posterior pituitary gland
what are the 2 types of hormones and their subdivisions
water soluble: polypeptides and amines
lipid soluble: steroids and amines
name all water soluble hormones (9)
(polypeptides)
insulin
growth hormone
oxytocin
PTH
calcitonin
thymosin
(amines)
epinephrine
norepinephrine
melatonin
name all lipid soluble hormones (5)
(steroids)
estrogen
progesterone
testosterone
corticosteroids
(amines)
thyroid hormone (T3 and T4)
which type of hormone binds to an extra cellular receptor
water soluble
lipid soluble binds to intra cellular receptor because it can cross the barrier
describe intracellular receptors
lipid soluble hormones can cross plasma membrane and bind to receptors
often act as transcription factors
describe extracellular receptors
water soluble hormones cannot cross the plasma membrane and must bind to
receptors on plasma membrane
binding to receptor will initiate intracellular pathways (enzyme activation, gene expression)
why do hormones act at a specific location and not everywhere in body (since they are released into blood stream)
target cells have the specific receptor for the hormone
what is the hypothalamus
neuroendocrine tissue
connects endocrine and nervous system
what do neurosecretory cells of hypothalamus produce
oxytocin
ADH (anti diuretic hormone)
hormones that regulate release of hormones from anterior pituitary gland
what is the posterior pituitary
continuous with hypothalamus
stores and secretes hormones produced by hypothalamus
name the 2 hormone secreted from posterior pituitary
oxytocin and ADH
describe oxytocin (posterior pituitary)
stimulates contraction of uterus and mammary glands
secretion is regulated by nervous system
describe ADH (posterior pituitary)
promotes water retention (acts on collecting ducts of kidneys)
secretion regulated by hypothalamus in response to blood osmolarity
describe anterior pituitary
hypothalamus produced hormones that regulate anterior pituitary
anterior pituitary produces many hormones
name and describe the hormones hypothalamus produces to regulate anterior pituitary
releasing hormones = stimulates release of hormones from anterior pituitary
inhibiting hormones = inhibits release of hormones from anterior pituitary
how does hypothalamus regulate anterior pituitary (pathway)
secretes the hormones (releasing/inhibiting) into blood and acts on anterior pituitary
name all 8 hormones secreted by anterior pituitary
growth hormone (GH)
prolactin (PRL)
follicle stimulating hormone (FSH)
luteinizing hormone (LH)
thyroid stimulating hormone (thyrotropin, TSH)
adrenocorticotropic hormone (ACTH)
melanocyte stimulating hormone (MSH)
endorphins
describe target and effect of growth hormone (GH)
target = liver, bones and other tissues
effect = stimulates growth and metabolism
describe abnormalities of growth hormone (GH) - 3 conditions
gigantism = excessive GH during development
acromegaly = excessive GH during adulthood
hypopituitary dwarfism = childhood GH deficiency
describe target and effect of prolactin (PRL)
target = mammary glands
effect = stimulates milk production and secretion
describe target and effect of follicle stimulating hormone (FSH)
target = ovaries and testes
effect = stimulates production of sperm and ova (follicle maturation)
describe target and effect of luteinizing hormone (LH)
target = ovaries and testes
effect =
ovaries - triggers ovulation and release of estrogen/progesterone
testes - testosterone production
describe target and effect of thyroid stimulating hormone (TSH)
target = thyroid gland
effect = stimulates production and secretion of thyroid hormone
describe target and effect of adrenocorticotropic hormone (ACTH)
target = adrenal cortex (outer layer of adrenal glands)
effect = stimulates production of glucocorticoids (like cortisol)
describe target and effect of melanocyte stimulating hormone (MSH)
target = melanocytes (skin pigmentation)
effect = stimulates production of melanin
describe target and effect of endorphins
target = nervous system
effect = inhibits pain perception (mimicked by heroin and other opiate drugs)
what are tropic hormones
have other endocrine tissues as their target
give 2 examples of tropic hormones
hypothalamic releasing hormones
anterior pituitary hormones
which anterior pituitary hormones are tropic
thyroid stimulating hormone (TSH)
follicle stimulating hormone (FSH)
luteinizing hormone (LH)
adrenocorticotropic hormone (ACTH)
generally describe the hypothalamus-anterior pituitary-endocrine organ axis
external conditions —> hypothalamus —> releasing hormone —> anterior pituitary —> tropic hormone —> endocrine gland —> hormone
(the hormones released inhibit the cycle, negative feedback mechanism)
describe pathway (basic) using TRH (hypothalamus-anterior pituitary-endocrine organ axis)
thyroid releasing hormone —> TSH —> thyroid gland —> thyroid hormone (T3/T4)
describe pathway (basic) using corticotropin releasing hormone (hypothalamus-anterior pituitary-endocrine organ axis)
corticotropin releasing hormone —> ACTH —> adrenal cortex —> glucocorticoids
describe pathway (basic) using
gonadotropin releasing hormone (hypothalamus-anterior pituitary-endocrine organ axis)
gonadotropin releasing hormone —> LH & FSH —> gonads —> sex hormones
what does TSH do (thyroid gland)
stimulates thyroid gland to release thyroid hormone (TH)
what does thyroid hormone consist of
2 iodine containing amine hormone
triiodothyronine (T3)
thyroxine (T4)
what does thyroid hormone regulate
metabolic processes
how is the level of thyroid hormone in blood regulated (and explain)
by negative feedback
TH inhibits release of TSH from anterior pituitary and release of TRH from hypothalamus
name 2 thyroid disorders
hyperthyroidism
hypothyroidism
describe hyperthyroidism
excessive secretion of thyroid hormone
describe hypothyroidism
insufficient production of thyroid hormone
symptom = goiter (associated with iodine deficiency)
why does hypothyroidism cause goiter
no negative feedback occurs
thyroid gland is overstimulated by TSH
what is a goiter
enlargement of thyroid gland
what are the parathyroid glands
4 small glands on back of thyroid gland
what do parathyroid glands do
release parathyroid hormone (PTH)
describe parathyroid hormone (PTH)
peptide hormone
raises Ca2+ (calcium) levels in blood
how does parathyroid hormone raise calcium levels
by stimulating
osteoclasts to break down bone
kidneys to reabsorb calcium and activate vitamin D (helps absorption of calcium in intestines)
what does thyroid gland do
releases calcitonin
what is calcitonin
peptide hormone
lowers calcium levels in blood by promoting uptake of calcium by bones
what regulates blood calcium levels
calcitonin and PTH
describe the relationship between calcitonin and PTH
antagonistic hormones
they have opposing effects
when would calcitonin be released
when calcium levels are high
when would PTH be released
when calcium levels are low
describe pineal gland
small mass of tissue near center of mammalian brain
what does pineal gland secrete
melatonin
what is the secretion of melatonin regulated by
light/dark cycles
via the SCN
describe regulation of blood sugar by insulin (where is it secreted by and function and when it’s released)
secreted by beta cells (pancreas)
lowers blood sugar levels by stimulating cells to take up glucose
released in response to high blood sugar
describe regulation of blood sugar by glucagon (where is it secreted by and function and when it’s released)
secreted by alpha cells (pancreas)
raises blood sugar by stimulating breakdown of glycogen in liver and muscles
released in response to low blood sugar
what are some symptoms of diabetes mellitus
frequent urination
excess thirst
excess hunger
ketones in urine
name and briefly describe the types of diabetes mellitus
type 1 = insulin dependent diabetes
type 2 = non insulin dependent diabetes
describe type 1 diabetes mellitus
autoimmune disorder
beta cells destroyed
describe type 2 diabetes mellitus
target cells have decreased sensitivity to insulin
what is the treatment for type 1 diabetes mellitus
insulin injection
what is the treatment for type 2 diabetes mellitus
medication
lifestyle and diet changes
describe thymus gland
produces a peptide hormone called thymosin
what does thymosin do
stimulates development of T lymphocytes
what is erythrocyte production regulated by
the hormone erythropoietin
what is erythropoietin
produced in kidneys
in response to low O2 levels in tissues (hypoxia)
to stimulate production of RBCs (erythropoiesis)
what is melatonin
amine hormone
affects biological rhythms
like sleep, appetite, body temp
what is released from adrenal medulla
catecholamines (norepinephrine/epinephrine)
what is the secretion of catecholamines regulated by
nervous system
what are the effects of catecholamines
raises blood glucose levels (breakdown of glucose)
sympathetic effects (increase HR, divert blood into skeletal muscle/skin from digestive system, dilates pupils, etc)
what is released from adrenal cortex (3)
glucocorticoids (cortisol, corticosterone, cortisone)
mineral corticoids (ex=aldosterone)
sex hormones (androgens)
name the corticosteroids (released from adrenal cortex)
glucocorticoids
mineralcorticoids
what is the secretion of glucocorticoids regulated by
ACTH
what is the secretion of mineralcorticoids regulated by
angiotensin II
what are the effects of glucocorticoids
raises blood glucose levels (gluconeogensis)
reduces inflammation
what is gluconeogensis
synthesis of glucose from fats and proteins
what are the effects of mineralcorticoids
regulates salt water balance in body
(reabsorption of Na* and secretion of K+ in the kidneys)
what does the adrenal gland regulate
stress
describe how adrenal medulla regulates stress
short term stress response
stressful stimuli causes hypothalamus to activate sympathetic nervous system
epinephrine/norepinephrine
describe how adrenal cortex regulates stress
long term stress response
stressful stimuli causes hypothalamus to secrete releasing hormone that stimulants release of ACTH from anterior pituitary
corticosteroids
what are the effects of epinephrine and norepinephrine in regulation of stress
glycogen broken down to glucose = increased blood glucose
increased blood pressure
increased breathing rate
increased metabolic rate
changes in blood flow patterns = leads to increased alertness and decreased digestive,
excretory and reproductive system activity
what are the effects of mineralcorticoids in regulation of stress
retention of sodium ions and water by kidneys
increased blood volume and blood pressure
what are the effects of glucocorticoids in regulation of stress
proteins and fats broken down and converted to glucose = increased blood glucose
partial suppression of immune system
