Endocrine System (Topic 7) Flashcards
hat do exocrine glands do? (2)
secrete substances into a duct onto an epithelial surface
What are some examples of exocrine glands? (2)
- Sweat glands
- salivary glands
- tear ducts
- sebum
- stomach bile?
What do endocrine glands do? (2)
secrete substances into the interstitial fluid, then into the blood stream
What type of gland secretes hormones? (2)
endocrine gland
What is a hormone? (2)
a chemical messenger produced by an endocrine cell and travels through the blood stream
What are iodinated amino acids? (4)
modified amino acid
What are biogenetic amines? (4)
derived from amino acids
What is a peptide hormone? (4)
polymers of amino acids (most hormones)
What is a steroid hormone? (4)
lipids
What are the thyroid hormones? (5)
- Triiodothyronine (T3)
- Thyroxine (T4)
What are characteristics of thyroid hormones? (5)
- Iodine stored in thyroid.
- Can be produced for several weeks even without iodine consumption.
What do thyroid hormones do? (5)
Regulate metabolic rate, growth, and brain development.
Are thyroid hormones polar or nonpolar? (5)
NONPOLAR
Are thyroid hormones polar or nonpolar? (5)
NONPOLAR
Characteristics of nonpolar messengers? (5)
have intracellular receptors and bind to affect gene expression
Where are thyroid hormone receptors found? What does this mean? (5)
the nucleus
- they cross the membrane by diffusion
- they alter gene expression
What are the precursors for biogenic amines? (6)
Starts as an amino acid, does not end up as an amino acid
What are catecholamines? (5)
biogenic amines dervied from tyrosine
What are the three catecholamines? (5)
- epinephrine
- norepinephrine
- dopamine
Characteristics of epinephrine? (5)
- = adrenalin
- secreted by the adrenal medulla
- Controls metabolism
- Neurotransmitter
Characteristics of norepinephrine? (5)
- secreted by the adrenal medulla
- Can be converted to epinephrine
Characteristics of dopamine? (5)
- produced by hypothalamus,
- secreted in portal circulation to affect secretion of prolactin by pituitary gland.
Characteristics of histamine? (5)
- derived from amino acid histidine
- involved in bronchoconstriction and vasodilation
Characteristics of serotonin and melatonin? (5)
- derived from amino acid tryptophan
- Regulation of intestinal movement
- Role in mood, appetite, sleep, circadian rhythms
How are peptide and protein hormones made? (7)
transcription and translation
What category do most hormones fall in? (7)
peptide and protein hormones
How are protein hormones released from the endocrine cell? (8)
exocytosis
how do protein hormones affect the target cell? (8)
They’re Polar; they will do what any water-soluble messenger will do
Characteristics of steroid hormones (9)
- cyclic lipids
- derived from cholesterol
- Nonpolar
Are steroid hormones polar or nonpolar? (9)
Nonpolar
Steroid Hormone Synthesis (10)
- (set of enzyme mediated reactions)
- starting point is cholesterol
- 1-2 G-Protein coupled receptor
- cAMP production by activated adenylyl cyclase
- cAMP activates (phosphorylates) a kinase
- cholesterol released from lipid droplet
- transported to mitochondria
- back and forth between smooth ER and mitochondria
- released from cell by diffusion b/c its a steroid (small and nonpolar)
Why do steroid hormones not travel in vesicles? (10)
vesicles are for polar, lipid-soluble
- steroid are non polar and water soluble
If steroid hormones sit free in the blood, what happens to them? (10)
they’ll clump together
Where are steroid hormones made? (11)
the kidney/adrenal gland and sex organs
What are corticoids secreted by? (11)
adrenalcortex
What does aldosterone do? (11)
mineralocorticoid, affects ionic balance (at kidneys).
What does cortisol do? (11)
glucorticoid; affects glucose metabolism
- Body’s response to stress
- Regulation of the immune system
What steroid hormones are made in the sex organs? (12)
androgens and estrogens
True or False. Sex hormones are exclusive to each sex. (12)
False
Would testes or ovaries produce more aromatase? (12)
ovaries (does more conversion of androgen to estrogen)
What does the ability of a cell to respond to a hormone depend on? (13)
the presence of receptors on or in the target cell
How is number of receptors regulated for water-soluble hormones? (13)
Exocytosis (upregulation) and endocytosis (downregulation=
How is number of receptors regulated for lipid-soluble hormones? (13)
- Alter gene expression (take in more or less)
- alter protein degradation
What is permissiveness? (14)
one hormone is required for another hormone to have its full effect
What can hormones do to receptors of target cells of other hormones? (14)
up-regulate them, increasing the response
What is an example of a hormone up-regulating the receptor of another hormone? (14)
Epinephrine targets adipocytes (fat cells) causing cells to release more fatty acids. Thyroid hormone up-regulates epinephrine receptors.
What does “the thyroid is permissive to epinephrine” mean? (14)
the response is bigger when both hormones are present.
thyroid is required for epinephrine to have its full effect
What can all endocrine disorders be categorized into? (15)
- too little hormone -> HYPOsecretion
- too much hormone -> HYPERsecretion
- reduced responsiveness of target cells -> HYPOresponsiveness
- increases responsiveness to target cells -> HYPERresponsiveness
Why do symptoms vary in endocrine disorders? (15)
they vary depending on the hormone or endocrine gland that is affected
What is the hypothalamus composed of? (16)
nervous tissue
What is the hypothalamus linked to? (16)
the pituitary by the infundibulum
What does the hypothalamus bridge? (16)
bridges neural and endocrine systems
what are the two lobes f the pituitary gland? (16)
anterior and posterior
What are the two posterior pituitary hormones? (17)
oxytocin and vasopressin (antidiuretic hormone; ADH)
- both peptide hormones
is oxytocin positive is negative feedback? (17)
positive
Examples of oxytocin release? (17)
- baby suckling
- birth
How can you tell oxytocin is a peptide? (17)
because of all of the amino acids in the structure
(lots of amine groups and double bonded oxygens)
What does vasopressin do? (18)
increase blood pressure
What category does posterior pituitary hormones fall in? (18)
neurohormones
What is the control of the anterior pituitary composed of? (19)
glandular epithelium (aka endocrine)
What does the control of anterior pituitary do? (19)
amplify signals produced by a few neurons
What is a tropic hormone? (20)
hormone that leads to the release of another hormone
Which hormones in the anterior pituitary pathway tropic? (20)
GHRH, SS, TRH, DA, and CRH
What is the difference between permissive and tropic hormones? (20)
- permissive works together to increase the response
- tropic leads to the production of another
What are the functions of cortisol? (22)
- maintains blood pressure
- prevents blood glucose from dipping too low
- puts “brake” on immune system to keep from overreacting
What does permissive action on the response to epinephrine and norepinephrine by muscles and blood vessels help maintain? (22)
maintains blood pressure
What does maintains cellular concentrations of metabolic enzymes required to produce glucose between meals do? (22)
prevents blood glucose from dipping too low
What does decreases events associated with the inflammatory response such as capillary permeability and production of prostaglandins do? (22)
puts “brakes” on immune system to keep from overreacting
What is common in diseases marked by reduced cortisol? (22)
autoimmune disorders
What is cortisol important for? (22)
fetal development (lungs, brain, intestines)
What is stress? (23)
situation with real or potential threat to homeostasis
What is the response to trauma, infection, pain, sleep deprivation, fright, etc.? (23)
stress
What happens when stressed? (23)
increased release of cortisol and epinephrine
- effects on organic metabolism
- enhanced vascular reactivity
- unidentified protective effects against stress
- inhibition of inflammation and specific immune responses
- inhibition of nonessential functions
What is adrenal insufficiency and its symptoms? (24)
plasma levels of cortisol are chronically below normal
- weakness, lethargy, loss of appetite
- low blood pressure; low blood sugar
(life-threatening if not treated)
What are some causes of adrenal insufficiency? (24)
Primary adrenal insufficiency (called Addison’s Disease)
- infectious diseases (such as tuberculosis) destroy adrenal gland cells
- adrenal gland tumors
- autoimmune attack of adrenal gland
Secondary adrenal insufficiency (reduction in ACTH)
- may arise from pituitary disease
What is Cushing’s Syndrome? Primary? Secondary? (25)
Excess cortisol in the blood
Primary
- cortisol-secreting tumor of the adrenal gland
Secondary
- usually due to an ACTH-secreting tumor of the pituitary
What are symptoms of Cushing’s Syndrome? (25)
- Osteoporosis
- Muscles weakness
- High Blood Sugar
- Immunosuppression
- Redistribution of fat
- High blood pressure
[Usually not fatal]
What does prolactin target? (26)
the breasts and milk-secreting cells
Where is prolactin produced? (26)
the anterior pituitary
What type of feedback does TRH have? (27)
negative feedback
What is the thyroid composed of? (28)
follicles
- follicular epithelial cells
- lumen containing colloid (protein-rich material)
What do thyroid follicles produce? (28)
T4 and T3
Where are thyroid hormone receptors? (29)
in the nucleus
What do thyroid hormones do? (29)
activate gene transcription
What do thyroid hormones receptors have a higher affinity for? (29)
T3 and T4
What type of actions does thyrpid hormone do? (29)
Metabolic:
- Increase absorption of carbohydrates
- Increase release of fatty acids by adipocytes
- Main action: stimulate Na+/K+ pumps
Permissive:
- up-regulate adrenergic receptors, mostly in heart and neural system
Growth and development:
- Lack of T3 and T4 cause slow growth
- T3 and T4 necessary to develop dendrites, synapses and myelin
- Lack leads to profound intellectual deficiencies
What is hypothyroidism? (30)
Damage or loss of function of thyroid
Often autoimmune
What is another cause of hypothyroidism and what is the symptom called? (30)
- lack of iodine in the diet
- goiter
What are some treatments for hypothyroidism? (30)
- iodine treatments if the lack is the cause
- synthroid (synthetic thyroid pills)
What causes hyperthyroidism? (30)
- Hormone-secreting tumor
- Over growth/activity
(can be cause BY a goiter)
What are some treatments for hyperthyroidism? (30)
- take beta blockers
What is a mitogen? (31)
something that stimulates mitosis
How do mitogens directly effect growth? (31)
it affects mitosis and cell division
What leads to bone growth? (32)
osteoblasts and chondrocytes
What do osteoblasts do? (32)
convert cartilagenous tissue to bone
What do chondrocytes do? (32)
creates new cartilage
What are epiphyseal growth plates? (32)
actively proliferating cartilage
What is the role of IGF-1? (32)
Stimulates differentiation and cell division of chondrocytes.
When does cartilage growth slow down and epiphyseal plates fuse? (33)
after puberty
Why are extracellular levels of calcium tightly controlled? (34)
How is calcium acquired and maintained? (34)
Bone:
- Reserve: 99% of body calcium
- Osteoblasts bone-forming cells; secrete a matrix that gets mineralized with Ca2+
- Osteoclasts break down bone by secreting H+; releases Ca2+ from bone
Kidneys:
- Active reabsorption after urine is filtrated
Gastrointestinal tract:
- Absorption from food through active transport
(All three are under hormonal control)
Osteoblasts vs osteoclasts (34)
Osteoblasts:
- bone-forming cells; secrete a matrix that gets mineralized with Ca2+
Osteoclasts:
- break down bone by secreting H+; releases Ca2+ from bone
What is parathyroid hormone secreted by? (35)
secreted by four parathyroid glands that are embedded in the thyroid gland
Go over Parathyroid hormone pathway! (35)
yayyyy thyroidddd
absorption vs Reabsorption vs resorption (35)
- absorption = taking in
- reabsorption = in the kidney because its gets filtered out and taken in again at the kidney
- resorption = bones (bone is broken down to free up the calcium)
What does vitamin D do to calcium absorption? (37)
it increases it in the GI tract
Where do we get vitamin D? (37)
diet and sunlight
Where is calcitonin secreted? (36)
from the thyroid, parafollicular cells
What does calcitonin do? (36)
- Opposite effect of parathyroid hormone
- Decreases plasma calcium concentration by inhibiting osteoclasts.
- Secretion stimulated by high plasma calcium concentration.
- Role doesn’t seem to be significant in day-to-day Ca2+ regulation.
(May work only when Ca2+ levels are very high)
