Endocrine System Flashcards
What are the four types of chemical messengers in the endocrine system?
Hormones
Autocrines
Paracrines
Secondary messangers
What are general characteristics of the Endocrine system?
coordinates and integrates all activity of body cell with NS to maintain homeostasis
influences metabolic activities
responses occur more slowly by act longer than NS
Hypothalamus has neuroendocrine functions
target cells are almost all body cells
What are hormones?
long distance signals that travel in blood/lymph
what are autocrines?
local chemical msgers that have effect on cells that produce them
what are paracrines?
local messengers that effect other cells
What are secondary msngers?
produced in a cell and cause that cell to respond
What are the two major classes of hormones?
Amino acid based and steroid based
What are steroid based hormones synthesized from?
cholestrol
What do hormones do to target cells?
change membrane permability induce secretions activate or inactivate enzymes stimulate synthesis of enzymes or other regulatory molecules stim mitosis
Do amino acid based hormones use direct or indirect mechanisms ?
indirect
Do steroid based hormones use direct or indirect mechanisms?
Direct
Why do amino acid based hormones use indirect?
What is the only AA based hormone that doesnt use indirect? why
lipid insouble
Thyroid (water soluble)
What do the indirect methods include? (2)
G protein and secondary messenger
What is a major indirect method and how does it work?
hormone binds to receptor which receptor changes shape and binds to G protein which binds to GTP and is ativated which then binds to and activated adenylate cyclase which is an enzyme that converts ATO ti cycylic AMP(2nd msgner) triggering response of target cell via protein kinases which activate or inactivated other proteins
What is CAMP? and what destroys it?
second messenger, stim response of targ cell bt peorwin kinases
phosphodiesterase
What are direct methods of hormones used by(what kinds)?
Why can they use this mechanism?
What kind of receptors do they act on and what does it activate?
Steroid . thyroxine
lipid soluble so can dissolve through phospholipid bilayer
act on intracellular receptors the directly activate genes
How do direct hormone mechanisms work?
hormone passes through cell/nuclear membrane –> bind to chaperonin complex receptor –>moves to DNA and binds to receptor protein-> turns on gene stimulating DNA trascription for mRNA which directs protein synthesis
What are characteristics of hormones?
Specific (only cells with specific receptors respond)
Trigger cell function on or off
degree of response to hormone is variable (concentration, number/affinity of receptors on cell)
Hormones can regulated #/affinity of receptors on targ cell or for other hormones
Effective at low concentrations, and quickly destroyed
speed/ duration varies
What is up regulation on target cells by hormones?
Target cells form more receptors in response to rising hormone levels
Target cells become more sensitive to horone
What is down regulation by hormones on target cells?
Why important?
target cells lose receptors in response to high levels of hormones preventing over reaction
How are hormones removed from blood?
enzynes, kidneys liver
What are the three types of reactions between hormones?
Permissiveness
Synergism
Antagonism
Permissiveness Interaction?
one hormone can’t react without the presence of another
Thyroxine and reproductive hormones
Synergism Interaction between hormones?
2+ hormones exert a greater effect then one alone
glucagon and epinephrine on blood sugar
Antagonism\ interaction between hormones?
have opposite effects on target tissue
What is the humoral stimulus for release of hormones?
Changing levels of component in blood directly stims secertion
What is the neural stimulus for release of hormones?
Nerve fibers stimulate release of hormones
ex. symp NS triggers epinephrine from adren medulla
What is hormonal releaseof hormones ?
hormones trigger secretion of others by endocrine glands
ex. hypothalamic horms stim released of horms from many other exo glands
How does NS maintain homeostasis?
modifies stimulation of endocrine glands and their neg fb controls systems to maintain homeostasis
What are the major endocrine organs?
Pituitary gland/hypothalamus Thyroid Gland Parathyroid Gland Adrenal Glands Pancreas Pineal Gland
Where is pituitary gland found?
Hypothalamus, protected by sella turcica of sphenoid bone
What are the two lobes of the pituitary gland called?
Posterior and anterior
What are hormones released by posterior pit?
ADH/Oxytocin
What are hormones secreted by anterior pituitary?
GH TSH ACTH (adrenocorticotropic hormone) Gonadotropins (FSH/LH) Prolactin
Where are ADH and oxytocin released from and where are they released into in response to what being stimulated?
Pit Gland into capillaries in response to neuron stimulation
Nerve connection b/w hypothalamus and post pituitary is called?
hypothalamic-hypophyseal tract
What stimulates release of ADH?
targets?
Effect?
Neural/humoral - increased blood osmolarity, decreased BV
Target –> kidney tubules
Effect increased reabsorption of water to blood
What is hyposecretion of ADH caused by?
What does it do?
diabetes insipidus
excrete large volumes of dilute urine, low BP/BV
What causes hypersecretion of ADH?
What does it result in?
Neurosurgery, trauma, cancer cells
decreased urine output, retention, increased BV&BP
What secretes oxytocin?
What is the stimulus?
What does it target?
What does it play a role in for both sexes?
What does it promote in non-sexual relationships?
Post HT neural - cervical stretching/sucking uterus- contraction labour, breasts initiates milk ejection Sexual arousal nurturing and affectionate bhvr
What is the anterior hypophysis considered?
Master gland
What does anterior hypophysis have vascular connection with?
Where does it carry releasing and inhibing hormones from and to?
What does it control?
What does it secrete?
What are all hormones considered? and what kind of mechanisms to all but GH use?
Hypophyseal portal veins hypothalamus to ant pit secretions of hormones from ant pit GH, TSH, ACTH, Gonadotropins, Prolactin proteins, via 2nd messenger mechs using cAMP
What does GH stimulate?
promote?
What indirectly mediated most effects of GH? (IGF)
most cells, especially targets bone/skeletal muscle
protein synthesis and encourages use of fats 4 fuel
Insulin Growth Factor
Other are direct action of GH
What is the stimulus for release of GH?
Where is the stimulus from?
When is stimulus usually released?
GHRH
HT
Mostly during sleep but nutrition, sleep patterns and stress change it
What are the effects of GH?
What does it stimulate liver, skeletal muscle, bone and cartilage to do?
What does it exert and what does this do?
To release IGF to promote bone and muscle growth
anti insulin effects
mobilizes fat, increases blood glucose by decreasing glucose uptake, encourages glycogen breakdown
What does hyposecretion of GH cause?
pit dwarfism
What does Hypersecretion of GH cause?
Gigantism in children
in adults acromegaly
What is the TSH stimulus for release?
What does it target?
What is its effects?
TRH from HT
Thyroid gland
normal secretion and development of Thyroid gland
What is adrenocorticopic hormones stimulus for release?
What does it target?
What does it effect?
CRH from HT, released greatest in AM before awakening, decreases as adrenocortical hormones rise, stress inhibits
adrenal cortex
release of corticosteriods
(hypersecretion is just increase in release of that0
What is the stimulus for release of FSH and LH?
What does FSH stimulate?
What does LH hormone stimulate?
What do both interact to do in females?
What does this cause release of?
After puberty GnRH from HT
Gamete formation
gonadal hormone production
both interact to control ovarian cycle in females stimulating estrogen and progesterone release from ovaries
What is the Prolactins stimulus for release?
What does it do?
What does hyposecretion cause?
What does hypersecretion cause?
PRH from HT, (suckling)
Lactation
poor milk production
menses stop, innapropriate lactation, infertilitiy
what does the thyroid gland contain?
2 lobes connected by isthmus
follicle cells –> thyroglobulin
lumen of follicles stores colloid
parafollicular cells - calcitonin
What do follicle cells in the thyroid gland produce?
thyroglobulin
Wwhat two things are used to form thyroxine?
thyroglobulins/iodine atoms
what do parafollicular cells produce
calcitonin
What are the two thyroxines?
T4&T3
What is T4 composed of?
2 tyrosines and4 bound iodine molecules
what is t3 made of?
2 tyrosine and 3 bound iodine atoms
How is T4/T3 synthesized?
Starting after tsh binds to receptors on follicle cells
tsh causes follice cells to produce thyroglobulin which is stored as colloid in lumen, iodine is actively transported out of blood into colloid and is oxidized into I2 which is then added to thyroglobulin to form T1/T2 which join together to form t3/t4. Follicle cells take in Colloid by endocytosis and enzymes split t4/3 from colloid and are diffused out of cells –>blood then bind to transport proteins to go to target cell.
What is The stimulus for release of thyroxines?
low levels cause HT to secrete TSH
What do thyroxines have an effect on?
most bod tissues
What are thyroxines many effects? 4
increases metabolism,
aids in normal function of heart, muscles, skeleton, DT, repoduction
regulates tissue growth
development of NS
What does hypothyroidism cause in adults?
Myxedema - low bmr, cold, constipation, phys/mental sluggishness
Goiter - lack of dietary iodine but same symptoms plus enlargment of thyroid gland
What does hypothyroidism in infants cause?
cretinism - irreversible mental and phys retardation, treat with thyroid hormone
What does hyperthyroidism do?
High BMR, overactivity
Graves’ disease - autoiummune disorder, over secretion
What is calcitonin released by and which cells produce it?
What can it used to treat?
What does it stimulate/inhibit?
thyroid gland, parafollicular cells
osteoporosis, Paget’s disease
osteoblasts
osteoclasts
Where are parathyroid glands located and how many are there?
posterior of HT and 4
What does the parathyroid gland secrete?
What kind of cell is it secreted by?
Parathroid hormone - controls blood calcium levels in adults acts to increase CA levels
Chief/parietal cells
What does the PTH do?
What is its stimulus for secretion
What are its three Targets?
What is its effect?
major control over CA in blood
Humoral (decrease in Ca detected by parathyroid glands)
Skeleton - stims osteoclast to release more Ca
Kidneys - ^ reabsorbtion of ca from urine and activation of vit D
Digestion - vitamin D increases absorption of ca from food
raises Ca in blood
What can hypersecretion of Parathyroid hormone cause?
bones lose salts and become spongey, adversely affects NS, kidney stones
What does Hyposecretion of Parathyroid Hormone do?
low ca, hyperexcitivity of neurons, tetany, respiratory paralysis and death
What is the outer layer of adrenal glands?
inner layer?
Cortex
medulla
What kind of tissue makes up adrenal cortex?
What does it synthesize and secrete?
Grandular tissue
Steroid hormones
What part of the NS is the adrenal medulla part of? what does it secrete?
Sympathetic
Catecholamines
How many layers are in the adrenal cortex?
What are its products synthesized from?
What are the 3 hormone groups it produces?
3
cholestrol
mineralcorticoids, glucocorticoids, gonadocorticoids
What is the main mineral corticoid?
what do mineralcorticoids regulate?
Aldosterone
electrolytes in extra cellular fluids especially Na,K
What is the importance of mineral corticoids regulating Na?
affects BV, BP, levels of other ions
What is the importance of mineral Corticoids regulating K?
Sets RMP of neural, muscle cells
What is the stimulus for secretion of mineral corticoids?
Humoral, hormonal, neural
1) decrease in bp,bv,na –>activates angiotension mech which ^ aldosterone release
2) HT responds to stress, secretes CRH->ant pit releases ACTH->adrenal cortex releases aldostrone
3) direct humoral - low blood na, high K - adrenal cortex
What is the Target of mineral corticoids?
Kidney Tubules
Kid Tubules secrete k, reabsorb na, water follows increasing BP BV and Na and decreasing k
What inhibits secretion of mineral corticoids by adrenal cortex?
bp to high, heart secrets atrial natriuetic peptide inhibiting renin and aldosterone
What is hyposecretion of mineral corticoids cause?
Addison’s disease –> weight lose, decreased blood Na, glucose, dehydration, hypotension
What does hyper secretion of mineral corticoid cause?
Alderstonism
excess na and water retention - Increase BP,BV, edema, loss of blood k causes neurons to be non functiona–>muscle weakness–>paralysis
What are glucocorticoids mainly?
Cortisol, cortisone, hydrocortisone
What does glucocorticoids do (cortisol)?
main Blood sugar levels, BV, essential
Maintain BP by increasing vasocontrictor action
What is the stimulus for release of Glucocorticoids?
Whats its effect?(4)
HT releases CRH causing ant pit to release ACTH acting on adrenal cortex to produce glucocorticoids
Helps to resist stressors
Gluconeogenisis
increased blood sugar
depressed inflamm/immune responses
What does hyposecretion of glucocorticoids cause?
Hypersectretion?
Addison’s disease (mineral and glucocorticoids) - decrease in glucose/na, weigh loss, dehydration, hypotension, hypoglycemia
under continued stress- supression of immune/inflamm
Cushing’s syndrome
What is gluconeogenesis?
protein and fats converted to glucose or catabolized for energy
What is Cushing’s syndrome?
Hyperglycemia, muscle and bone loss, poor healing, increase in na and water retention
What are gonadocorticoids considered?
What are they converted to in males/females?
What is thought to be their role
What may it cause in women and converted to after menopause?
Hypersecretion of it?
Androgens testostrone/estrogen onset of puberty sex drive/estrogen masculine women/ prepubertal males
What kind of cells do the adrenal medulla have?
What do these secrete?
What does it reinforce effects of?
what does it increase?
what does it interact with in response to stress?
Chromaddin, epinephrine, norpinephrine sympathetic Ns in response to Fight or flight bP, HR, blood sugar adrenal cortex
What does hyposecretion of the adrenal medulla cause?
Nothing, Sympathetic Ns covers deficit
What does hypersecretion of adrenal medulla cause?
rare, massive uncontrolled sympathetic NS stimulation
rapid HBR, high BMR, hypertension/glycemia
What types of cells does the pancrease have?
What do their secretions together regulate?
Alpha cells
beta cells
Blood glucose level - antagonistic interaction
What do the alpha cells in the pancreas produce?
What does this do?
Glucagon - raises Blood sugar
What do beta cells in pancreas produce?
What does this do?
insulin, decrease blood sugar
What is stimulus for glucagon release in pancreas?
What does it target?
What effect does this have?
drop in blood glucose
liver : gylcogenolusis(gycogen->glucose->blood)
Gluconeogenesis( lacticacid/fat/protein->glucose)
raises Blood glucose
What stimulates insulin release?
increase blood sugar
What does insulin target?
Whats the effect?
Liver (glucose->glycogen->storage)
Muscle/fat cells take up glucose
inhibits gluconeogenesis
lowers blood glucose
What does hypoactivity of insulin cause?
What are symptoms?
diabetes mellitus
polyuria
polydipsia
polyphagia
Hypersecretion of insulin?
hypoglycemia which causes less glucose to gte to brain which results in convulsions–>unconsciousness and death
What causes the symptoms of diabetes mellitus?(hypo activity of insulin)
glucose cant enter cells for membrane transport in absence of insulin
lack of fuel for ATP production
more fats mobilized which increases fatty acids in blood making ketone bodies causing acidosis and ketouria and can lead to coma/death
Where is pineal gland located and what does it secrete?
third ventricle in brain
melatonin
what does melatonin effect?
timing of sexual maturation and puberty
day and night cycles
circadian rhythu,s of body
What do ovaries produce?
What does it stimulate?
What does it cause development of?
What do the hormones together control?
estrogen and progestrone
growth and maturation of reproductive system
secondary sex characteristic
uterine cycle and synch it with ovarian
What do the Testes produce?
What does this hormone do?
testostrone
growth/development of reproductive system, secondary sexual characteristics, spermatogenesis and sex drive
What does the Placenta secrete?
What do these influence
estrogen
progesterone
HCG
What does the thymus secrete?
What does this do?
Thymopoietin, thymic factor, thymosin
cause T cells to become immunocompetent
What does heart secrete in response to what?
What does this target?
What are the effects of the hormone?
atrial natriuretic peptide high bv,bp, na kidney tubules inhibits release of aldosterone decreases reabsorption of na
What do kidneys secrete?
What is this in response to/
What does this target?
What does this stimulate?
Erythropoietin
low blood 02
red bone marrow
RBC production
What does the skin secrete?
What is that an inactive form of?
Where is it activatied?
What does PTH stimulates the release of it?
Choleccalciferol vitamin D liver and kidney vitamin D aids calcium absorption from digestive tract stimulates release of vitamin D
What does adipose secrete and when?
leptin - uptake of glucose/lipid
produces resitin an antagonist of insulin
