endocrine system Flashcards
negative feedback
response reverses the trend
types of hormones
peptides, amines, and steroids
peptide hormones
DNA–> RNA–> protein
stored in vesicles
released via exocytosis when cell is stimulated
water soluble
steroids
main class of hormones
derived from cholesterol
lipid soluble
- diffuse through membranes
amino acid-base hormones
derived from the amino acids
water soluble
how do hormones work
travel through the blood
bind to receptor on target cells
up-regulation
more receptors–>bigger response
down-regulation
fewer receptors–> smaller response
cells without receptor are insensitive
are proteins and most amines water soluble
yes
extracellular receptor
gene regulation
cytoplasmic response
are steroids water soluble
no
what does plasma transport
proteins
intracellular receptor
gene regulation
plasma membrane hormone receptors
- first messenger(hormones like epinephrine) binds receptors on the plasma membrane of cells
2.hormone binding to the receptor activates a g-protein
-activates adenylyl cyclase
-converts ATP to cAMP
- cAMP is a second messenger
- mediates a cell-specific response - phosphodiesterase enzyme breaks down cAMP
- terminates the signal
intracellular hormone receptors
- hormone binds receptor in the cytoplasm
- translocates to the nucleus - hormone-receptor complex binds to a DNA sequence
- triggers gene transcription and translation - protein production
- can then mediate changes in cell function
-can cause secretion of other hormones
what are the 5 endocrine glands
pituitary, thyroid, parathyroid, thymus, and adrenal glands
Hypothalamic-pituitary axis (HPA)
connection between nervous and endocrine systems
major regulator of most hormones
pituitary gland
located at the base of the brain
connected to the hypothalamus by the pituitary stalk
anterior pituitary
posterior pituitary
anterior pituitary
regulated by hormones from the hypothalamus
posterior pituitary
hormones produced in hypothalamus
transported down axons
released from posterior pituitary
what hormones does the anterior pituitary secrete
- called adenohypophysis
TSH
ACTH
FSH
LH
GH
PRL
MSH
releasing or inhibiting hormones from hypothalamus delivered via hypophyseal portal system
promotes or stops release of hormones from anterior pituitary
posterior pituitary pt2
called neurohypophysis
-neural tissue
releases two hormones
1. ADH(vasopressin)
-antidiuretic hormone
2. oxytocin
- uterine contractions and milk let down
thyroid gland
located in anterior neck
- anterior surface of trachea
two lateral lobes connected by median tissue(isthmus)
largest pure endocrine gland
what is the thyroid gland composed of
spherical follicles surrounding colloid
follicle cells
- produce thyroid hormone and protein thyroglobulin
parafollicular cells
- produce calcitonin
parathyroid glands
usually two pairs of gland but can be up to 6
on posterior of thyroid gland
- secrete a parathyroid hormone that regulated blood calcium levels via osteoclasts, intestines and kidneys
adrenal glands
pyramid-shaped gland on to top of kidney
2 regions
- adrenal cortex(outer)
-adrenal medulla (inner
adrenal cortex …. continue from ppt
zona glomerulosa
-outer
…
adrenal medulla
innervated by autonomic nervous system
secrete epinephrine and norepinephrine
pancreas
behind stomach
mixed gland
- endocrine and exocrine
pancreas islets of langerhans
endocrine pancreas
produce pancreatic hormones
pancreatic hormones
alpha cells
-glucagon
beta cells
-insulin
regulates blood sugar level and digestion rate
pineal gland
part of the epithalamus
produces melatonin
- sets biological clock
induces drowsiness
mostly released at night
testes
male gonads
secrete androgens
-steroid hormones (testosterone)
androgens
produced in interstitial cells
sperm maturation
protein synthesis in muscles
male secondary characters
ovaries
female gonads
estrogen and progestins
estrogen
produced by follicular cells
female secondary characteristics
follicle stimulation
progestins
produced by corpus luteum
prepares uterus for implantation
prepares mammary glands for secretion
heart
atria contain endocrine cells
what do endocrine cells produce
atrial natriuretic peptide (ANP) hormone
also carry urine
- regulates blood pressure, volume, and sodium concentration
- stimulates kidney to increase slat secretion and production of salty urine
Gastroentestinal tract (GI)
endocrine cells within organs
secrete hormones that promote digestion, hunger and satiety
kidneys
small amounts of endocrine tissue
release several hormones and renin
what is the purpose of renin
important for blood pressure(enzyme)
what do kidneys also contain
calcitriol and erythropoietin
calcitrol
steroid hormone
steroid form of vitamin D
stimulates calcium and phosphate absorption from small intestine
erythropoietin
peptide hormone produced when oxygen in blood is low
stimulates production of red blood cells
thymus
deep in thorax to the sternum
large in children
-diminished in size in adults
produces thymosins
thymosins
develop and mature the immune response
adipose
fat cells
produce hormone leptin
leptin
feeling of satiety
needed for reproduction
types of stimulation glands
hormonal
humoral
neural
hormonal stimulation of glands
- Hypothalamus releases TRH when a higher metabolism is needed
-TRH causes the anterior pituitary to release TSH - TSH goes into the blood
- binds to receptors on the thyroid gland
-stimulates the thyroid gland to release thyroid hormones t3 and t4 - t3 and t4 in the blood result in
- increased metabolism
growth
development
negative feedback to the hypothalamus and anterior pituitary
humoral stimulation of gland
- blood glucose rises after a meal
glucose sensors in beta-cells of pancreas release insulin in response to high glucose
inulin causes cells to take up glucose
blood glucose falls
glucose sensors in alpha-cells of pancreas release glucagon in response to low glucose
glucagon causes liver to release stored glucose
neural stimulation of glands
stress
action potential in sympathetic nerves going to the adrenal medulla
release of epinephrine and norepinephrine into the blood
e and ne cause
- liver and muscle cells break down glycogen into glucose
heart to beat faster and harder
dilate the bronchioles in the lungs
shunt blood to essential organs
adenylate cyclase
an enzyme that catalyzes the conversion of ATP to cyclic AMP
adrenal cortex
outer portion of adrenal glands that produces corticosteroids
adrenal gland
endocrine glands associated with the kidneys
adrenocorticotropic hormone (ACTH)
hormone released by the anterior pituitary, which stimulates the adrenal cortex to release corticosteroids during the long-term stress response
aldosterone
steroid hormone produced by the adrenal cortex that stimulates the reabsorption of Na+ from extracellular fluids and secretion of K+
alpha cell
endocrine cell of the pancreatic islets that produces the hormone glucagon
amino acid-derived hormone
hormone derived from amino acids
androgen
male sex hormone such as testosterone
beta cells
endocrine cell of the pancreatic islets that produces the hormone insulin
calcitonin
hormone produced by the parafollicular cells of the thyroid gland that functions to lower blood Ca2+ levels and promote bone growth
colloid
fluid inside the thyroid gland that contains the glycoprotein thyroglobulin
corticosteroid
hormone released by the adrenal cortex in response to long-term stress
cortisol
glucocorticoid produced in response to stress
down-regulation
a decrease in the number of hormone receptors in response to increased hormone levels
endocrine gland
gland that secretes hormones into the surrounding interstitial fluid, which then diffuse into blood and are carried to various organs and tissues within the body
epinephrine
hormone released by the adrenal medulla in response to a short term stress
erythropoietin (EPO)
hormone produced by the kidneys to stimulate red blood cell production in the bone marrow
estrogens
a group of steroid hormones, including estradiol and several others, that are produced by the ovaries and elicit secondary sex characteristics in females as well as control the maturation of the ova
first messenger
the hormone that binds to a plasma membrane hormone receptor to trigger a signal transduction pathway
G-protein
a membrane protein activated by the hormone first messenger to activate formation of cyclic AMP
G-protein
a membrane protein activated by the hormone first messenger to activate formation of cyclic AMP
glucagon
hormone produced by the alpha cells of the pancreas in response to low blood sugar; functions to raise blood sugar levels
glucocorticoid
corticosteroid that affects glucose metabolism
gluconeogenesis
synthesis of glucose from amino acids
glycogenolysis
breakdown of glycogen into glucose
goiter
enlargement of the thyroid gland caused by insufficient dietary iodine levels
gonadotropin
hormone that regulates the gonads, including FSH and LH
hormonal stimuli
control of hormone release in response to changes in extracellular fluids such as blood or the ion concentration in the blood
hyperglycemia
high blood sugar level
hyperthyroidism
overactivity of the thyroid gland
hypoglycemia
low blood sugar level
hypophyseal portal system
system of blood vessels that carries hormones from the hypothalamus to the anterior pituitary
insulin
hormone produced by the beta cells of the pancreas in response to high blood glucose levels; functions to lower blood glucose levels
islets of Langerhans (pancreatic islets)
endocrine cells of the pancreas
mineralocorticoid
corticosteroid that affects ion and water balance
neural stimuli
stimulation of endocrine glands by the nervous system
norepinephrine
hormone released by the adrenal medulla in response to a short-term stress hormone production by the gonads
oxytocin
hormone released by the posterior pituitary to stimulate uterine contractions during childbirth and milk let-down in the mammary glands
parafollicular cell
thyroid cell that produces the hormone calcitonin
parathyroid gland
gland located on the surface of the thyroid that produces parathyroid hormone
pituitary stalk
(also, infundibulum) stalk that connects the pituitary gland to the hypothalamus
plasma membrane hormone receptor
a hormone receptor on the surface of the plasma membrane of a cell
posterior pituitary
extension of the brain that releases hormones produced by the hypothalamus; along with the infundibulum, it is also referred to as the neurohypophysis
renin
enzyme produced by the juxtaglomerular apparatus of the kidneys that reacts with angiotensinogen to cause the release of aldosterone
thymus
gland located behind the sternum that produces thymosin hormones that contribute to the development of the immune system
thyroglobulin
glycoprotein found in the thyroid that is converted into thyroid hormone
thyroid gland
endocrine gland located in the neck that produces thyroid hormones thyroxine and triiodothyronine
