Introduction to endocrinology Flashcards
Hormone definition
Chemical substance secreted by a gland, group of glands, tissue
has a physiological control effect on other cells of the body
endocrine definition
secretes within the body
exocrine definition
secretes outside the body
how much time does it take to see hormonal effects
seconds (norepinephrine, epinephrine)
days weeks
months (thyroxine, GH)
how does the nervous system interact with the hormonal system
sympathetic nervous system can stimulate adrenal glands
CNS can control the pituitary gland
some hormones are controlled by the nervous system
what functions of the body does the endocrine system control (4)
chemical reaction rate of cells
transport of substances through cell membranes
growth of body
secretion of other hormones
pituitary gland anatomy
two halves
anterior controlled by other hormones and secretes 6 hormones
posterior pituitary under neural control and secretes 2 hormones
what 6 hormones does the anterior pituitary secrete
GH
adrenocorticotropin
thyroid-stimulating hormone
follicle-stiulating hormone
luteinizing hormone
prolactin
what 2 hormones does the posterior pituitary secrete
antidiuretic hormone
oxytocin
Adrenal glands
2 glands, 1 on top of each kidney
each gland has 2 parts
adrenal cortex under hormonal control and secretes 2 hormones
adrenal medulla under neural control and secretes 2 hormones
what hormones does the adrenal cortex secrete
cortisol
aldosterone
what 2 hormones does the adrenal medulla secrete
catecholamine hormones
adrenaline
noradrenaline
what hormones does the thyroid secrete
thyroxine (T4)
triiodothyronine (T3)
calcitonin
parathyroid glands
4 small glands located within the thyroid
secretes 1 hormone
what hormone does the parathyroid secrete
parathormone
islets of langerhans
in the pancreas
endocrine tissue
secrete several hormones like insulin glucagon
ovaries
endocrine gland
produce estrogen and progesterone
testicles
produce testosterone
placenta
endocrine tissue
secretes human chorionic gonadotropin
estrogens
progesterone
somatomammotropin
duodenum
contains brunners glands
secretin hormone
coordinates digestion
brown adipose tissue
receives hormonal input to help regulate body temp
not gland or tissue
local hormones
specific local effects on specific tissues
secretin
released from duodenal wall transported in blood to pancreas
cause pancreas secretions for digestion
cholesystokinin
released in small intestine transported to gall bladder and causes gallbladder contraction
pancreas cause secretion of digestive enzyme
adrenocorticotropin
released from pituitary gland stimulates adrenal cortex to secrete adrenocortical hormones
general hormones
effective on many parts of the body and cause many different reactions
ex: epinephrine, T3 T4 and GH
hormones classified on their basic chemical structure
steroid
protein
tyrosine
steroid hormones
based on the cholesterol molecule
hydrophobic
lipophilic
crosses easily plasma membranes of cells
where are the receptors for steroid hormones
within the cell cytoplasm or nucleus
pathway of steroid hormones
hormone enters the cytoplasm of the cell
binds with a receptor
diffuse or transported into nucleus
bind to and activate DNA strands
initiate transcription process of genes to form RNA messenger
RNA goes into cytoplasm through nuclear pore complex
promote functions inside the cells
epinephrine and norepinephrine
secreted by adrenal medulla under sympathetic stimulation
secreted by sympathetic nerves
causes constriction of blood vessels and increase of arterial pressure
has effects on most organs and tissues of the body
growth hormone
released from anterior pituitary
cause growth in all parts of the body
thyroid hormone T3 and T4
released from thyroid gland
increase chemical reaction rate in almost all body cells
tyrosine based hormones
important amino acid to make proteins
thyroid gland turns tyrosine into T3 and T4
adrenal medulla can turn tyrosine into epinephrine and norepinephrine
how does the thyroid gland use tyrosine
adds iodine molecules to tyrosine to make t3 and t4
how does the adrenal gland use tyrosine
hydroxylates tyrosine to make it hydrophilic
where are the receptors for t3 and t4
inside the cells
chain of events of thyroid hormones
TH
binds with receptor in cell nucleus
bind and activare DNA
initiate transcriptions of specific genes to form RNA messenger
RNA goes into cytoplasm through nuclear pore complex
new proteins (enzymes) are formed and become the controller to promote metabolic activities in all cells of body
what tyrosine based hormones need to interact with a receptor on the cell surface
E
NE
Ach
protein based hormones (example)
anterior pituitary hormones
posterior pituitary hormones
insulin and glucagon
parathormone
protein based hormones
hydrophilic
receptors at the surface of cell membrane
protein based hormones chain of events
bind to receptor
structure change in receptor
receptor becomes activated enzyme adenyl cyclase
activate the formation of cAMP
second messenger activates cascade of enzymes
second messenger
cell-signaling pathways that communicate between the receptor on the cell surface and the inside of the cell
second messenger example
cAMP
Ca2+-calmodulin
IP3 and diacylglycerol
t/f concentration of hormones is extremely low in blood
true
how can hormones be measured
radioimmunoassay RIA
mass spectrometry
RIA
the higher the percentage of bound radioactive hormones, the lower the concentration of the natural hormone to be measured
mass spectrometry
very precise but hard and expensive
secretion rate of hormones
body can control how much effect the hormone is having
homeostasis
what is the most common way of controlling secretion rate
negative feedback
inhibits its own secretion when level is high enough
direct negative feedback
hormone inhibits its own secretion when there is enough of it
indirect negative feedback
when the effect of the hormone inhibits the secretion
direct positive feedback
hormone goes back to the gland to promote secretion
indirect positive feedback
effect promotes the secretion
circadian rythm
when we sleep different hormones go up and down
hormone receptor regulation
receptors can be activated or deactivated by altering their second messenger
receptors can be destroyed by enzymes
receptors can be created by synthesis
