Intro to Endocrine (lect 1) Flashcards
Define Hormone
chemical substance that sends a message to another cell in the body
How are cellular messages sent to other cells in the body?
Via blood stream - endocrine
GI tract - exocrine
Neurolog - neurocrine
Intersistial - paracrine
What are a few glands covered in the endocrine system
hypothalamus, pituitary, thyroid, adrenal, pancreas, ovaries/testes
Describe Amine hormone classification
tryptophan or tyrosine (amino acid) modified
Epinephrine (tyrosine) Melatonin (tryptophan)
Very Short Half life
Describe Peptide
unbroken chain of amino acids 50 or less
hydrophilic, dont cross membrane easily
must first bind to membrane bound receptors
Describe Proteins
chains of amino acids 50 or less
primary,secondary,tertiary structures
Describe glycoproteins
conjugate proteins bound to carbs (galac/mannose/fruct)
solubility/half life similar to protein hormones
Describe Steriod
derived from lipid/typically cholesterol
hydrophobic, must be transported in blood bound to carrier proteins
can cross membrane
Describe fatty acid
small derived from arachidonic acid
rapidly degraded and effective for only seconds
Describe metabolism
Sum fo chemical processes that occur within a living organism to maintain life, includes catabolism and anabolism
T/F Hormones and all other cellular signals are not metabolized
false they are
What determins the extent to which hormones are metabolized of which they are capable of binding to receptors and eliciting intended effects?
Speed of catabolism (break down) and anabolism (creation)
What are some conditions that modify met. of hormones
speed of breakdown/creation
concentration of protein bound hormones will be affected by availibility to binding
cirrhosis can enhance enzymatic breakdowns
Describe what happens with alcohol consumption
increase degradation of testosterone
extended consumption - cirrhosis - less alb and binding proteins
What is the main two mechanisms of elimination
Kidney and liver
T/F blood passes through the kidney and is taged with certain hormones for destruction or creation of different molecules
false it passes through the liver
Describe steriod hormones
eliminated by inactivating metabolic pathways and excreted in urine and bile
Describe Thyroid hormones
inactivated by intracellular deiodinases
Describe catecholamine hormones
rapidly degraded within blood circulation
Describe fatty acid derivitive hormones
rapidly inactivated by metabolism and typically active for short period (seconds)
Briefly describe hormone transport
after release from endocrine, circulate in bloodstream in one of two forms:
protein bound or unbound
Free floating subject to metabolism
Describe solubility
water soluble (hydrophilic) or fat soluble (lipophilic)
Describe carrier proteins
fat-soluble hormones are transport bound to a carrier protein
Describe Micelles
enclosed packages in lipid-rich sub. with hydrophilic outerlayer and hydrophobic inner
Describe negative feedback mechanisms
most common
stimulus with feedback upstream to decrease production of itself
ex: thyroid
Describe postive feedback mechanisms
control mechanism that increases stimulus recieved until a endpoint is achieved
can easily go out of control
ex. coag cascade
Describe 1/2/3 disorders
disorder of endocrine characterized by organ dysfunction, whether it has regulating gland (2/3) or endocrine gland (1)
Thyroid is 1
Pituitary 2
hypothalamus 3
Describe other factors that affect hormone levels:
stress: well adaptive or mal adaptive
Time of Day: syst regulates func through external signals
mesnstration
menopause
food intake/diet
drugs
Hypothalamic/pituitary function
three distinct parts are?
anterior
indermediate lobe
posterior
what do post posterior arise from
diencephalon; storage and release of oxytocin and AVP
Briefly describe Anterior pituitary
80-90% blood supply and hypothalamus factors via hypo-hypo portal system
T/F Pituitary function can be detected between 7-9th week gestation
t
Describe lactotrophs:
somatotrophs:
thyrotrophs:
corticotrophs:
gonadotropphs:
Lacto: prolactin secreting
Soma: GH secreting
Thyro: TSH
Cortico: ACTH
Gonad: LH/FSH
T/F Afferent pathways to hypothalamus are integrated in various specific nucleli then resolved
Efferent pathways to higher brain centers, responses are similar to specific hormone charact. by negative feedback/pulsatity and diurnal variation
t
Briefly describe the endocrine feedback loop
hypothalamus, pituitary, thyroid axis
Hypophyseal unit: how do anterior hormones secrete?
pulse fashion, generally regulated by neural modulation and is specific to each unit
What is the interpulse for males and duration?
interpulse is 55 min, for LH, duration is 40 min
T/F pulse frequency of hypoth hormone GnRH does not have a major effect of LH secretion
false it does
t/f hormone nature is cyclic
true
T/F many hormones are secrected in different amounts depending on time
true, this is best shown with ACTH or TSH
ACTH peak 0600-0900
TSH nocturnal are 2x the day levels
Briefly describe pituitary tumors
20% harbor
10-30% during
account for 91%
enlargment seen in?
20% harbor clinically silent adenomas
10-30% in MRIs
account for 91% of lesions in pts undergone transpen, surgery
Enlargment seen in puberty/preg
What are the most clinically significant tumors of pituitary
prolactin, then null cells, then THS, GH, ACTH or gonado
Describe anterior pitutiary hormones
larger….
either…or….
larger and more complex than those synth in hypothalamus,either tropic or direct effectors
Give examples of tropic vs direct effectors for anterior pituitary hormones
LH
FSH
TSH
ACTH
(tropic)
IGF-1
Prolactin (direct
Describe growth hormone
vital for
ceases?
what stimulates GHRH
Stimulators?
vital for normal growth (pituitary)
growth ceases if pituitary removed, not restored unless GH administered
Somatotropin stimulates GHRH
Stimulators: sleep, excerise…etc
Actions of GH
what type of hormone
transition from…w/o?
direct antagonizer of?
STOMA….
amphibolic hormone (cata/anabolic)
transition from fed to fast state w/o shortage of substrate
direct antagoner of insulin/glucose metabolism
STOMATOMEDINS -IGF
major growth factor induced by GH is what
from liver
what can cross rxn w….causes?
what kind of testing for …. deficiencies/pathologies?
ICF-1 from the liver
ICF-2 can cross react with insulin and cause hypoglycemia
Glucose testing for diagn of acromegaly/GH def
Briefly describe GH pulsitity
based off
testing…
based on dyn phys of growth hormone axis
testing IGF-1 for assessing GH def and acromegaly/giagantism
Describe GH excess
usually tumor, before closure of long bones, gigantism
after puberty classical but soft bony tissues overgrowth, enlarged hands/feet
tumor ablation
Describe GH deficiency
children:
adults:
both adults and child
children: growth failure, short stature
adult: complete/partial failure of anterior pituitary
osteoporosis seen
Describe Prolactin
struct similar to GH and HPL
stress hormone, vital funct in relation to reproduction
tonic inhibitor
DOPAMINE INHIBITS PROLACTIN
Prolactinoma
pituitary tumor that secretes prolactin most common type of func pit. tumor
T/F in hyperprolactinemia greater than >150 correlates with tumor size
true
What must you obtain in order to eliminate primary hypothyrodismn disease causing elevations of prolactin in hyperprolactinemia?
obtain TSH/Free T4
Describe Idiopathic galactorrhea
lactation occuring in women with normal prolactin
usually in women who have been pregnant several times, no pathological implications
Briefly describe hypopituitarism
failure of….results in loss of…
complete…..
low/norm levels
failure of either pituitary or hypothalamus resulting in a loss of anterior pit. function
complete loss or loss of single monotropic
Low or norm levels of tropic hormone
T/F Both tropic and target hormones should be monitored w hypopitutiarism
true
Describe posterior pituitary hormones
extension of?
storage of?
tightly linked to?
synth outside of?
extension of forebrain
storage of AVP/Oxytocin
tightly linked to prod of neurophysin
SYNTH OUTSIDE OF HYPOTHALAMUS
Describe Oxytocin
critical for lactation/labor
positive feedback loop
Pitocin - synthesized oxytocin
linked to maternal bond
Describe AVP
regulates free water excretion in henles loop
potent pressor agent, blood clotting and factor VII release
diabetes insipidus
