Chapter 11 - The Endocrine System Flashcards
Name the three functions of the endocrine system:
- growth
- reproduction
- metabolism
What makes up the endocrine system?
- endocrine glands
- hormones
What are endocrine glands?
ductless glands that produce, store, and/or release hormones directly into the blood
What are hormones?
chemical messengers of the endocrine system that are carried to target cells that have receptors for those specific hormones
List the three classes of hormones based on their chemical structure.
What are they made of?
- amine hormones: derived from AA; short (tyrosine and tryptophan)
- peptide (protein-based) hormones: several AA long
- steroid hormones: derived from cholesterol
What are examples of amine hormones?
Lipid or water soluble, or both?
- norepinephrine and epinephrine - from tyrosine
- serotonin - from tryptophan
- Both: lipid OR water soluble
What are examples of peptide (protein-based) hormones?
Lipid or water soluble, or both?
I Get Oxy, Lets Feel Ghood
Insulin, Glucagon, Oxytocin, LH, FSH, GH
Water soluble only (hydrophilic/polar)
LH and FSH are glycoproteins; sugar bound to protien
Which hormones are glycoproteins?
What category based on chemical structure do they belong to?
LH and FSH
Peptide hormones
What are examples of steroid hormones?
Lipid or water soluble, or both?
TEA CT
testosterone, estrogen, aldosterone, cortisol, thyroid hormone
- lipid soluble only (hydrophobic/ nonpolar)
Compare a polar hormone with a nonpolar hormone in terms of solubility
polar: hydrophilic and water soluble
nonpolar: hydrophobic and water-insoluble (lipophilic)
Compare a polar hormone with a nonpolar hormone in terms of where their receptors are found on target cells
polar hormone: receptor on cell surface because charged/polar substances cannot pass through the CM
nonpolar hormone: receptor found on inside target cell because they can enter the target cell directly
Define the anterior pituitary (location and function)
Name the hormones found here
hangs from base of brain
produces, stores, and secretes 6 hormones
FLAT PiG
FSH, LH, ACTH, TSH, PRL, hGH
Function of the hGH? (human growth hormone)
What endocrine gland does it belong to?
to grow: bone, muscle, adipose tissue
anterior pituitary
Function of the TSH? (thyroid stimulating hormone)
What endocrine gland does it belong to?
secretes hormones by thyroid gland
anterior pituitary
Function of the ACTH? (adrenocorticotropic hormone)
What endocrine gland does it belong to?
secretes hormones by adrenal cortex
anterior pituitary
Function of the PRL? (prolactin)
What endocrine gland does it belong to?
produces milk (in mammary glands)
anterior pituitary
Function of the FSH? (follicle stimulating hormone)
What endocrine gland does it belong to?
maturation of sperm and ovarian follicle and ovum (egg)
anterior pituitary
Function of the LH? (luteinizing hormone)
What endocrine gland does it belong to?
secretes testosterone and causes ovulation (releases ovum)
anterior pituitary
The posterior pituitary gland does not produce its hormones, it only stores and secretes it. Where are the hormones found in the posterior pituitary produced?
hypothalamus
Define the posterior pituitary (location and function)
Name the hormones found here
behind anterior pituitary and stores and secretes 2 hormones
DOES NOT PRODUCE HORMONES
ADH,OT
Function of ADH (anti-diuretic hormone)
What endocrine gland does it belong to?
controls water balance (causes H20 to be reabsorbed into blood)
increases blood pressure
posterior pituitary
Function of OT? (oxytocin)
What endocrine gland does it belong to?
uterine muscle contraction and milk release (letdown reflex)
posterior pituitary
Define the thyroid gland (location and function)
Name the hormones found here
below larynx, around trachea
involved in iodine uptake and produces 3 hormones
T4, T3, CT
In the thyroid gland, which are the true thyroid hormones
T4 and T3, NOT CT
Function of T4? (thyroxine)
What endocrine gland does it belong to?
inactive thyroid hormone
thyroid gland
Function of T3? (triiodothyronine)
What endocrine gland does it belong to?
active thyroid hormone
increases metabolic rate by breaking down glc to produce ATP
thyroid gland
Function of CT? (calcitonin)
What endocrine gland does it belong to?
bone formation and regulates (decrease) Ca2+ in blood
thyroid gland
Define the adrenal glands (location and function)
Name the hormones found here
located atop kidneys; divided into adrenal medulla and adrenal cortex
- adrenal medulla: epinephrine and norepinephrine
- adrenal cortex: aldosterone, cortisol
Define the adrenal medulla (location and function)
Name the hormones found here
middle portion of adrenal gland and functions in sympathetic NS
- epinephrine
- norepinephrine
Define the adrenal cortex (location and function)
Name the hormones found here
outer portion of adrenal gland and produces many steroid hormones when stimulated by ACTH
- aldosterone
- cortisol
Function of epinephrine and norepinephrine?
What endocrine gland does it belong to?
increase heart/breathing rate
adrenal medulla (of adrenal gland)
Function of aldosterone?
What endocrine gland does it belong to?
increases blood pressure
adrenal cortex (of adrenal gland)
Function of cortisol?
What endocrine gland does it belong to?
increases blood pressure and weakens immune activity
adrenal cortex (of adrenal gland)
What endocrine gland contains structures called the Islets of Langerhans?
pancreas
Define the pancreas (location and function)
Name the hormones found here
behind stomach on left side
functions as both an endocrine and exocrine gland
contains Islets of Langerhans that produce 2 hormones
- insulin
- glucagon
Function of insulin?
What endocrine gland does it belong to?
when stimulated by high glucose levels, secretes insulin to lower blood glucose (moves glc from blood into cells -> glycogen formation in liver and skeletal muscle)
pancreas
Function of glucagon?
What endocrine gland does it belong to?
when stimulated by low blood glucose levels, secretes glucagon to raise blood glucose (breaks down glycogen and releases glucose)
pancreas
What cells produce insulin and glucagon in the pancreas?
insulin - beta cells of Islets of Langerhans
glucagon - alpha cells in Islets of Langerhans
Insulin and glucagon can be described as having __________ effects
antagonistic
What hormones do the ovaries (endocrine gland) make?
estrogen
progesterone
What hormones do the testes (endocrine gland) make?
testosterone
What are the islets of Langerhans and what do they secrete?
islands of endocrine cells
contain beta cells (secrete insulin) and alpha cells (secrete glucagon)
In general terms, explain how insulin lowers blood glucose levels and how glucagon raises blood glucose levels
Insulin moves glucose from blood into cells to form glycogen in liver and skeletal muscle cells
Glucagon breaks down glycogen to release glucose into blood
Some hormones, like epinephrine and norepinephrine, can also be neurotransmitters (NTs). What determines whether a hormone will act as a hormone vs a NT
depends which organ secretes them/binds to
ex: Epinephrine and norepinephrine can act as both NT and hormone.However, when they are released by a neuron then they’re acting as NT. However, when they are released by the adrenal medulla into the bloodstream, then they are acting as a hormone.
What mechanism can be used to regulate the amount of hormone released from an endocrine gland?
negative feedback
True or False: A target cell can only respond to one hormone
False, target cells can usually respond to multiple hormones at the same time (have receptors for multiple hormones)
hormones ______ the body and reaches the target cell which has ______ types of _______ receptors
circulate
two
hormone
What are the two types of hormone receptors?
What type of hormones bind to these receptors?
surface receptors: polar hormones
intracellular receptors: non polar hormones
Compare the location of surface receptors and intracellular receptors
surface receptors: found outside target cell
intracellular receptors: found inside target cell
Generally describe how hormones work
- hormones are produced, stored, and secreted into bloodstream
- circulates body until reaches target cell with hormone receptors (surface/intracellular receptors)
- hormone binds to its receptor on/in target cell -> receptor activated
- intracellular pathways are induced -> target cell activity is changed through changes in enzyme activity/changes in gene activity
What happens immediately after a hormone binds to its receptor and is activated?
intracellular pathways begin
After intracellular pathways occur, in what ways is a target cell’s activity altered?
gene/enzyme activity can be altered
Hormones are needed in _______ _____ amounts; are very _________
very small
potent (strong)
Why do hormones usually affect other parts of the body?
are spread in the blood stream
Hormones often have __________ effects, but effects are _______ _________
long-lasting
not immediate
Define what a half-life is
how long it takes to break down a hormone by 50%
Compare the half life of a NT to a hormone
NT have short half-life, while hormones have a longer half-life
Some hormones have an effect on the cell that ______ it (ex: ______________ hormone)
secreted
autocrine
(cell targets itself)
What are the different types of effects hormones can have on target cells?
synergistic effect
antagonistic effect
permissive effect
Explain the synergistic effect (how it works). Provide examples
two hormones that have the SAME function, and their combined effect is greater than the sum of their individual efforts
ex: epinephrine and norepinephrine both have an affect on increasing heart rate; but together, their combined effect is greater than the sum of their individual efforts
Epinephrine: increases heart rate by 10%
norepinephrine: increases heart rate by 20%
If both epinephrine affect the heart rate at the same time, does their combined effect increase heart rate by 30%?
No, they are synergistic and have the same function, so their combined effect will be much greater than 30% (maybe like 70% or smth)
Explain the antagonistic effect (how it works). Provide examples
one hormone opposes/inhibits another hormone
ex: insulin and glucagon are both involved in the regulation of blood glucose levels, but both have opposite effects (one lowers blood glc, while the other increases blood glc)
another example: calcitonin and parathyroid (PTH) regulate blood Ca2+ levels, but one lowers blood Ca2+ and the other increases blood Ca2+
Explain the permissive effect (how it works). Provide examples
one hormone permits/allows the other hormone to exert its full effect
ex: epinephrine (by itself) weakly stimulates lipolysis, but in the presence of T3, it increases the number of epinephrine receptors on target cell, so epinephrine has a greater effect
Compare the priming effect and desensitization
priming (upregulation) effect: increases # of hormone receptors on target cell for same/different hormone
desensitization (down regulation) effect: decrease # of hormone receptors on target cell to prevent overstimulation due to lingering hormone
The desensitization effect leads to a ________ response to a hormone after _____________ exposure
decreases
prolonged
(after prolonged hormone receptor -> decrease of hormone receptors -> decrease hormone reponse)
What is the stimulus for the production of T4 and T3?
low body temperature
(because producing T4 increases metabolic rate, which releases energy in form of heat)
“Draw” the hormone pathway that involved homeostasis of body temperature
stimulus: low body temp
hypothalamus -> TRH -> anterior pituitary -> TSH -> thryroid gland -> T4 and T3 (TH)
*if too hot, negative feedback will inhibit TRH (by hypothalamus) and TSH (by anterior pituitary) production
Water-soluble hormones must bind to…
water-soluble hormone receptors located on the surface of target cell
Water-soluble hormones are AKA?
polar/charged/hydrophilic hormones
Explain how negative feedback is involved in thermoregulation
producing too much heat (making too much T4 into T3), will signal negative feedback to stop the production/release of TRH by the hypothalamus or stop the production/release of TSH by the anterior pituitary (end product inhibition)
What category/type of hormone binds to extracellular/cell surface receptors? Why is the receptor located on the cell surface?
water-soluble (polar/charged/hydrophilic) hormones
located on the cell surface because they cannot pass through cell membrane
What category/type of hormone binds to intracellular receptors? Why is the receptor located inside the cell?
lipid-soluble (nonpolar/uncharged/hydrophobic) hormones
because they can pass through the cell membrane (cannot stay in extracellular environment bc they are hydrophobic)
Compare the end result from water-soluble hormones from lipid-soluble hormones
water-soluble hormones: changes enzyme activity (target cell physiology altered too)
lipid soluble: ↑ or ↓ in production of protein coded by genes (DNA)
List the 2 pathways water-soluble hormones use to deliver their message to the cell interior. Which hormone is capable of activating these 2 pathways?
adenylate cyclase - cAMP pathway: glucagon, epinephrine, LH
phospholipase c - Ca2+ pathway:
ADH, angiotensin, TSH
Describe how the adenylate cyclase – cAMP pathway works. What is the function/action of
active protein kinase?
water-soluble hormone binds receptor on cell surface → Gprotein’s alpha subunit dissociates → activates Adenylate cyclase → ATP converted to cAMP → cAMP activated PK → active PK phosphorylates enzymes (proteins) to deactivate or activate them.
Who acts as the second messenger in the adenylate cyclase - cAMP pathways? Why do we need these?
cAMP
need second messenger because water-soluble hormones can’t cross the cell membrane to deliver its message (to nucleus?)
Who acts as the second messenger in the phospholipase c - ca2+ pathways? Why do we need these?
IP3 or Ca2+
need second messenger because water-soluble hormones can’t cross the cell membrane to deliver its message (to nucleus?)
Describe how the phospholipase C – Ca++ pathway works. What happens to the Ca++ that gets
released into the cytoplasm (what does it bind to)?
water-soluble binds to receptors on cell surface → Gprotein’s alpha subunit dissociates → activates Phospholipase C → IP3 and DAG → IP3 binds to IP3 receptor on ER/SR → Ca++ released from ER/SR → activates Calmodulin-Ca++ → activates PK → active PK phosphorylates enzymes to deactivate or activate them
Ca2+ binds to inactive calmodulin to form Ca2+ calmodulin
True/False: calmodulin is an active compound
False, is active when bound to Ca2+ to make Ca2+ calmodulin
What is glycogenolysis, in which cell(s) does it take place, what 2 hormones promote glycogenolysis, and what is the end product of glycogenolysis?
Glycogenolysis: the process of breaking down glycogen into glucose
Liver cells + Skeletal Muscle Cells
Glucagon and Epinephrine
Glucose
List the 2 epinephrine receptors present on the liver cell
beta-adrenergic receptor (adenylate cyclase - cAMP)
alpha-adrenergic receptor (phospholipase C - Ca2+)
Regarding the binding of epinephrine to 2 distinct receptors, explain how the adenylate cyclase
and phospholipase pathways work, and the product formed by BOTH pathways that starts the
common pathway.
Adenylate cyclase uses cAMP to activate PK. Phospholipase pathway uses Calmodulin-Ca++ to activate PK.
What 2 compounds can activate protein kinase?
cAMP and Calmodulin-Ca++
True/False: phosphorylated enzymes are always active
false, they can be either inactive or active
In glycogenolysis, what 2 enzymes does active protein kinase phosphorylate? Do these two enzymes both become active when phosphorylated?
phosphorylase kinase ⓟ (active when phosphorylated)
glycogen synthase (inactive when phosphorylated)
What chemical reaction is catalyzed by active glycogen synthase? Is active glycogen synthase
phosphorylated or dephosphorylated?
Active glycogen synthase converts glucose into glycogen
Active glycogen synthase is dephosphorylated
In glycogenolysis, after active PK phosphorylates phosphorylase kinase into the active form, what happens after?
PK (active) -> phosphorylase kinase (active) -> glycogen phosphorylase (active) -> converts glycogen into glucose
Name all the enzymes involved in the converged pathway
- protein kinase
- glycogen synthase
- phosphorylase kinase
- glycogen phosphorylase
Name 2 specific locations within the cell where you can find lipid soluble hormone receptors
cytoplasm and nucleus
Because lipid-soluble hormones are hydrophobic, how are they carried to the target cell?
carried by a carrier protein through the blood to target cell
carrier protein does NOT enter target cell
What happens to the hormone-receptor (HR) complex if it is found in the target cell’s cytoplasm?
The HR complex must get translocated into the nucleus.
Where in the target cell does the HR complex ultimately need to be, and describe what it does once it arrives there.
Nucleus
Once inside the nucleus, the HR complex binds to a half-site of HRE to form a homodimer or heterodimer -> transcription into mRNA and translation to synthesize protein
What is the relationship between the promoter, hormone response element (HRE), and a half site?
promoters contain HRE which has 2 half-sites
What is a dimer, and compare a homodimer vs. a heterodimer
A dimer includes 2 half-sites of an HRE bound to 2 HR complexes.
if the 2 HR complexes are the same = homodimer
if different = heterodimer.
TRUE or FALSE: If only 1 half-site is occupied by a HR complex, the lipid soluble hormone will have an effect on the target cell
False. Both half-sites need to be occupied by HR complexes to have an effect
Which of the two thyroid hormones crosses the cell membrane, and which one crosses the nuclear membrane?
T4 crosses the cell membrane and T3 crosses the nuclear membrane.
Where in the target cell does T4 get converted in T3?
cytoplasm (but needs to move to nucleus)
Where in the target cell are T3 receptors located? How does that compare to other lipid soluble hormone receptors?
located in the nucleus bound to DNA
other hormone receptors are usually in the cytoplasm, therefore, they need to be translocated into the nucleus
Compare the location formation of the HR complex of a standard lipid-soluble hormone to the HR complex of a thryoid hormone (TH)
standard: HR complex formed in cytoplasm (bc receptors found there)
TH: HR complex formed in nucleus (bc T3 receptors found there)
For thryoid hormones, the HRE on the DNA has two half sites, one for _______ receptor and one for a _________ receptor
T3 receptor
9-cis-retinoic acid receptor (RXR)
Describe the other HR complex that forms a dimer with the thyroid hormone-
thyroid hormone receptor complex on the HRE.
9 cis retinoic acid and its 9-cis-retinoic acid receptor (RXR) occupy the other half-site on the HRE
