Hormones & Endocrine Systems

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Review Of Hormones, Chapters 7, 23.  Also Covers Study Guide Questions 5-8

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What are peptide hormones?
lipophobic hormones that contain copies of the hormone and a signal sequence to direct it to the RER
unable to enter target cell
What does it mean if a hormone is lipophobic?
it dissolves easily in extracellular fluidunable to enter target cells
What are steroid hormones derived from?
Where are steroid hormones produced?
gonads, placenta, cortex of adrenal gland
Are steroid hormones soluble in plasma?
no, they are lipopphyllic.most steroid hormones found in the blood are bound to a carrier protein.
What do gonads produce?
sex hormones
What is the mechanism of signal transduction for peptide hormones?
the bind to the cell surface receptors because they cannot enter the cell otherwise.
GPCR (G-protein coupled receptor)tyrosine kinase coupled receptorscAMP second messenger systems
Why is cell response to peptide hormones rapid?
because second messenger systems modify existing proteins.
What is a preprohormone?
mRNA on the ribosome binds amino acids into a peptide chain
inactivepeptide hormone synthesis
What is a prohormone?
enzymes in the ER chop off the signal sequence creating an inactive prohormone.
inactivebecomes activated during protranslational modification
What is protranslational modification?
when prolytic enzymes chop the prohormone into active hormone and other fragments
What is an echtohormone?
a hormone secreted by a cell to the external environmentex: pheremones
What makes a chemical a hormone?
it is secreted by a cell or group of cells into the blood or external environment
exerts it's effect at very low blood concentrations
What is a catecholamine?
fight or flight hormonesreleased by the adrenal glands in response to stresspart of the sympathetic nervous systemusually stimulant drugs
What is acetylcholinesterase?
degrades acetylcholineterminates synaptic transmission
What type of cells in steriod hormone synthesis can diffuse to target cells?
only unbound hormones can diffuse to target cells
What is a signal sequence?
in peptide hormone synthesis; directs the preprohormone into the RER lumen by a signal sequence of amino acids
Describe peptide hormone synthesis.
(1) comes off ribosome as a preprohormone containing 1 or more copies of the peptide hormone, signal sequence, and other fragments. the Signal sequence directs the hormone to the lumen of the RER. -inactive-(2) signal sequence is removed creating a small, still inactive molecule called a prohormone(3) @ the golgi apparatus, the prohormone is packaged with protolytic enzymes that chop the prohormone into active hormone and other fragments. This is called protranslational modification.(4) secretory vesicles are stored until the cell receives a signal for secretion. Vesicles then move to the cell membrane and release their contents by calcium dependent exocytosis.
Which hormones are lipophilic?
steriod hormones
Which hormones are lipophobic?
peptide hormones
Describe quickly peptide hormone synthesis
ribosome --> preprohormone --> signal sequence --> prohormone --> prohormone activating protranslational modification --> another signal --> cosecretion
What is negative feedback?
a pathway in which the response opposes or removes the signal.
The pancreas releases which hormones? What is the main effect of these hormones?
releases: insulin glucagon somatostatin pancreatic polypeptide
main effect: metabolism of glucose and other nutrients
Where are steroid hormones synthesized? How often are they synthesized?
in the smooth ER
steroid hormones are only synthesized as needed as they cannot be stored in vesicles.
How are steroid hormones converted to active hormone?
actively and quickly
hormone concentration in the cytoplasm rises and hormones move out by simple diffusion
How is the half life of steroid hormones extended?
the binding of steriod hormones to a carrier protein extends the half life by protecting the hormone from enzyme degradation.it also blocks the hormones entry into the target cell
Where are receptors for steriod hormones found?
cytoplasm or nucleus
What is the transcription factor of steroid hormones? What is the effect of activating new genes? What produces new proteins for cell processes?
binds to DNA, activating or repressing on or more genes
activating new genes creates new mRNA that directs the synthesis or new proteins.
*translation produces new proteins for cell processes.
How are peptide hormones released from parent cells?
by exocytosis
Describe the half life of peptide hormones.
short half life
What is the target response to peptide hormones?
modification of existing proteins & the induction of new protein synthesis
Give two examples of peptide hormones.
insulin parathyroid hormone
Which hormones are made in advance and stored in secretory vesicles?
peptide hormones
Give three examples of steroid hormones. Where are they produced?
estrogen, cortisol, androgens
the endocrine cells of gonads produce these hormones
What synthesizes and secretes steroid hormones?
the adrenal cortex
How are hormones classified?
by source, receptor, and chemical structure.
What is the key feature of hormonal cascade?
negative feedback
How does the hormonal cascade proceed?
stimulus --> hypothalamus releases hypophysio-trophic hormone --> anterior pituitary releases trophic hormone --> target gland releases third hormone (ex cortisol)
Specifically, what hormones does the adrenal cortex synthesis and release?
(1) aldosterone (mineralcorticoids)(2) androgens (sex hormones) andro = man(3) glucocorticoids (cortisol)
What is cortisol? What does it have the ability to do?
the main glucocorticoid secreted by the adrenal cortex. It has the ability to increase plasma glucose concentrations
What is a trophic hormone?
a hormone made and released by the anterior pituitary and target endocrine glands.
What is the adrenal cortex tropic hormone? (ACTH)
a peptide hormonestimulates the adrenal cortex to release glucocorticoids

What is the target of ACTH? What does it do?
steroidogenic cells of the adrenal cortex
stimulates the synthesis and release of glucocorticoids. Steriods are not stored.
What are the three types of hormone interaction?
synergistic, permissive, and antagonistic interactions
Describe synergism.
a hormonal interaction where two hormones together produce a greater effect than the sum of their individual effects.It can occur with not only hormones, but two or more chemicals in the body.
Give an example of synergism.
Potentiation- "epinepherine potentiates glucagon's effect on blood glucose levels."
Describe permissive interactions.
a hormonal interaction where one hormone cannot fully exert its effect unless a second hormone is present. *the second hormone is the permissive hormone*
Give an example of a permissive interaction.
because thyroid hormone by itself cannot stimulate maturation of the reproductive system, thyroid hormone is considered to have a permissive effect on sexual maturation.
Describe antagonistic interactions.
when two hormones work against eachother, sometimes one diminishes the effectiveness of the other.The tendancy of one substance to oppose the action of another.One hormone may decrease the # of receptors fo the opposing hormone.
Give an example of an antagonistic hormone interaction.
Growth hormone decreases the number of insulin receptors
What is a functional antagonist? Give an example.
when two hormones have opposing physiological actions.Ex: growth hormone increases glucose due to the functional antagonism of insulin.
The pituitary is composed of how many glands?
two fused glands- anterior and posterior
What is the anterior pituitary gland? What controls the secretion of these hormones?
endocrine gland that secretes 6 hormones.
secretion is controlled by the hypothalamic neurohormones.
Name the hormones secreted by the anterior pituitary and their abbreviations.
1. Prolactin (PRL)2. Thyrotropin (TSH)3. Adrenocorticotropin (ACTH)4. Growth Hormone (GH)5. Follicle Stimulating Hormone (FSH)6. Lutenizing Hormone (LH)
What is the target of the hormone PRL?
prolactic; breast/mammary glands
What is the target of the hormone TSH?
thyrotropin; thyroid gland
further initiates release of--> thyroid hormones --> many tissues
What is the target of the hormone ACTH?
adrenocorticotropin; adrenal cortex
further initiates release of--> cortisol --> many tissues
What is the target of the hormone GH?
growth hormone; musculoskeletal system & liver
further initiates the release of --> insulin-like growth factors --> many tissues
What is the target of the hormone FSH and LH?
Follicle stimulating hormone and Lutenizing hormone; endocrine cells of the gonads
further initiates the release of--> androgens, estrogens, progesterone --> germ cells of the gonads
What is the posterior pituitary?
the storage and release site for 2 neurohormones- vasopressin (ADH) and oxytocin
Where are the hormones of the posterior pituitary made and packaged?
in the cell body of neurons in the hypothalamus
Describe the synthesis, storage, and release of posterior pituitary hormones.
(1) hormone is made & packaged in the cell body of neurons in the hypothalamus.(2) vesicles are transported down the cell(3) vesicles contraining the hormone are stored in the posterior pituitary.(4) synapse to the vein & are transported to the blood. Chemical signal/stimulus reaches the hypothalamus sending an electrical signal from the neuron cell body to the distal (distant) end of the cell, releasing the vesicle contents into circulation.
Describe the synthesis, storage, and release of anterior pituitary hormones.
(1) neurons synthesizing trophic hormones release ant. pit. hormones from the hypothalamus to the capillaries of the portal system.(2)portal vessels carry the trophic hormones directly to the anterior pituitary(3) endocrine cells release their hormones into the second set of capillaries for distribution to target organs.
What is vasopressin? Where is it stored and released?
(ADH) antiduirectic hormoneregulates water balance in the bodyconsists of 9 amino acidsstored and released in the posterior pituitary gland.
What is oxytocin? Where is it stored and released?
control the ejection of milk during breast feeding and contractions of the uterus during labor.stored and released in the posterior pituitary.
What is a reflex pathway?
stimulus, input signal, integration of the signal, an output signal, and a response.
What is a simple reflex pathway. Give an example.
The response of the pathway serves as the negative feedback signal that turns off the reflux.increase blood glucose= stimulus. insulin secretion = efferent pathwaydecrease in blood glucose = response
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