DAT Endocrine System Flashcards
Endocrine
synthesizes and secretes
hormones into the bloodstream
Exocrine
secretes enzymes into ducts
Paracrine
cell signaling where the
target is nearby
Autocrine
cell signaling via hormone or
chemical messenger that binds to
receptors on the same cell
Hormone
are transported throughout
the body in blood, a small amount has a
large impact, and compared to the
nervous system, the endocrine system is
slower, indirect, and longer lasting
Peptide hormones
synthesized in the
rough ER and modified in Golgi (requires
vesicles to cross membrane). They act on
surface receptors typically via secondary
messengers (e.g., cyclic AMP)
Peptide hormones are…
water soluable
where are peptide hormones manufactured?
rough ER as a
larger pre-prohormone → cleaved in
ER lumen to prohormone → cleaved
again and modified with
carbohydrates in Golgi to final form
→ packaged by Golgi into secretory
vesicles for release via exocytosis
Example of receptor-mediated
endocytosis
protein stimulates
production of second messengers
Anterior pituitary peptide hormone exampel
follicle
stimulating hormone (FSH),
luteinizing hormone (LH),
adrenocorticotropic hormone
(ACTH), human growth hormone
(hGH), thyroid stimulating
hormone (TSH), prolactin
Posterior pituitary peptide hormone example
anti-diuretic
hormone (ADH)
Parathyroid gland peptide hormone example
parathyroid
hormone (PTH)
Pancreas peptide hormone example
glucagon and insulin
Steroid hormones
synthesized from
cholesterol in the smooth ER; are
hydrophobic, which means they freely
diffuse but require a protein transport
molecule to dissolve in blood; have
intracellular receptors
Direct stimulation (steroid hormone)
steroid hormone
diffuses past the plasma membrane
and binds to receptors in the
cytoplasm → hormone + receptor are
transported to the nucleus → binding
activates a portion of DNA, acting at
the transcription level
Adrenal cortex steroid hormone example
glucocorticoids
and mineralocorticoids (cortisol
and aldosterone)
Gonads steroid hormone example
estrogen, progesterone,
testosterone (estrogen and
progesterone are also produced
by the placenta)
Tyrosine derivatives
- formed by
enzymes in cytosol or on the rough ER
Thyroid hormones
are lipid
soluble, require a protein carrier in
the blood, and bind to receptors in
the nucleus. The response has a
latent period and increased
duration. These hormones increase
transcription of many genes in
nearly all cells of the body
Catecholamines
epinephrine and
norepinephrine are tyrosine
derivatives that are water soluble,
dissolve in blood, bind receptors on
target tissue, and mainly act via
second messenger cAMP
Receptor location varies…
receptors
can be on the membrane or inside the
cell, and hormone regulation can occur
by increasing or decreasing the number
of receptors in response to hormone
amount.
Negative feedback
- the effect
produced by a hormone is
monitored, and any deviations from
a set “normal” level lead to
adjustments that bring the system
back to that normal level.
Hypothalamus
monitors the external
environment and internal conditions of
the body. The hypothalamus contains
neurosecretory cells that link the
hypothalamus to the pituitary gland, and
is therefore considered the link between
the endocrine and nervous system.
hypothalamus secretes what hormones..
ADH (vasopressin) and oxytocin to
be stored in the posterior
pituitary
Gonadotropin releasing hormone
(GnRH) from neurons, which
stimulates the anterior pituitary to
secrete FSH and LH
Anterior Pituitary
mainly regulates
hormone production by other glands and
is regulated itself by the hypothalamus
Direct (non-tropic) hormones
directly stimulate target organs
hGH
aka somatotropin,
stimulates bone and muscle
growth
Prolactin
stimulates milk
production in females from
mammary gland cells.
Melanocyte stimulating
hormone (MSH)
stimulates
melanocytes to produce and
release melanin
Endorphins
- inhibit perception
of pain (is technically a
neurohormone)
Tropic hormones
stimulate other
endocrine glands
ACTH
stimulates adrenal
cortex → release glucocorticoids
via second messenger cAMP.
TSH
stimulates thyroid gland
which in turn increases in size, cell
number, and rate of secretion of
hormones T3 and T4.
LH
in females, stimulates
formation of corpus luteum, and
in males, it stimulates interstitial
cells of testes to produce
testosterone
FSH
in females, stimulates
maturation of ovarian follicles to
secrete estrogen, and in males,
stimulates maturation of
seminiferous tubules and sperm
production
Posterior Pituitary
composed mainly
of support tissue from nerve endings
extending from the hypothalamus.
Does not synthesize hormones, but
stores ADH and oxytocin produced by
the hypothalamus.
ADH/vasopressin
increases
reabsorption of water by increasing
permeability of the nephron’s
collecting duct → water
reabsorption and increased blood
volume and pressure. Coffee and
alcohol block ADH, therefore
increasing urine volume
Oxytocin
- secreted during
childbirth, increases strength of
uterine contractions and stimulates
milk ejection by stimulating
contraction of smooth muscle cells
in the uterus and mammary glands
Pineal gland
secretes melatonin which
plays a role in the circadian rhythm
Thyroid
located on the ventral surface
of the trachea, just in front of the trachea
Thyroxine (T4) and triiodothyronine
(T3)
are lipid soluble tyrosine
derivatives (contain iodine)
Derived from tyrosine and
necessary for growth and
neurological development in
children, as well as increasing
basal metabolic rate (BMR) in the
body (negative feedback on TSH)
Hypothyroidism
under secretion
→ low heart rate, respiratory rate,
and BMR
Hyperthyroidism
over secretion
→ increased BMR and sweating
(both hypo and hyperthyroidism
lead to goiter, or enlargement of
thyroid gland)
Calcitonin
peptide hormone that
‘tones down’ Ca2+ in blood
Stimulates osteoblast activity,
which builds up bone by using up
the Ca2+ in the blood
Achondroplasia
results in
dwarfism
Progeria
premature aging,
wrinkled skin, arthritis, and
arteriosclerosis
Parathyroid
four pea-shaped
structures attached to the back of the
thyroid
Parathyroid hormone (PTH)
helps maintain the right balance of calcium in the bloodstream and in tissues that depend on calcium for proper functionin
Thymus
involved in immune response,
secretes thymosins that stimulate WBCs
to become T cells that identify and
destroy infected body cells
Adrenal gland
- rest on top of the
kidneys
Adrenal cortex (outer portion)
secretes only steroid hormones
Glucocorticoids (cortisol and
cortisone)
raise blood glucose
levels, which stimulates
gluconeogeneis in the liver, and
degrades adipose tissue to fatty
acids for use as energy
Mineralocorticoids (aldosterone)
increases reabsorption of Na+
and excretion of K+ in kidneys
Cortical sex hormones
androgens are male sex
hormones; a small amount is
secreted, which is significant in
females but not in males, since
they have testes producing
much more
Adrenal medulla
secretes Epinephrine and norepinephrine
Pancreas
has bundles of cells called
Islet of Langerhans which contain two
cell types: alpha and beta; also has
delta cells
Alpha cells secrete
glucagon -
catabolic, and released when energy is
low, thus raising blood glucose levels
Beta cells secrete
insulin - anabolic,
released when blood levels of
carbohydrates/proteins are high, thus
lowering blood glucose levels
Delta cells release
somatostatin -
somatostatin inhibits both insulin and
glucagon.
Testosterone
spermatogenesis,
secondary sex characteristics
Estrogen
menstrual cycle,
secondary sex characteristics
Progesterone
menstrual cycle,
pregnancy, regulates formation of
internal reproductive structures
Gastrin
breaks down food in
stomach, stimulates secretion of HCl
Secretin
small intestine; when acidic
food enters from stomach, this
neutralizes acidity of chyme by
stimulating the release of alkaline
bicarbonate from the pancreas
Cholecystokinin
small intestine;
presence of fats causes contraction of
gall-bladder and release of bile,
which is involved in the digestion of
fats and tells pancreas to release
enzymes for digestion
