Lecture 2 Flashcards
(179 cards)
1
Q
Intracrine mediation
A
Intracrine substances regulate intracellular events
2
Q
what types of hormones can enter the cell (and reach receptor) ?
A
lipophilic hormones (ex: steroid hormones: sex hormones)
3
Q
Because steroid hormones are lipophilic, they can
A
can pass through cell membrane and bind to receptor in cell
4
Q
Typically when we are thinking about hormones that bind in the cell we are talking about
A
steroid hormones
5
Q
autocrine mediation:
A
autocrine substances feed back to influence the same cells that secreted them
6
Q
paracrine mediation:
A
paracrine cells secrete chemicals that affect adjacent cells
7
Q
endocrine mediation:
A
endocrine cells secrete chemicals into the blood stream, where they may travel to distant target cells
8
Q
ectocrine mediation:
A
ectocrine substances such as pheromones are released into the environment by individuals to communicate with others
** pheromones vs allomones
9
Q
pheromones
A
Chemical messengers used to communicate with individuals same species (a type of ectocrine mediation)
10
Q
allomones
A
chemical messengers used to communicate between individuals of different species (a type of ectocrine mediation)
11
Q
endocrine mediation
A
endocrine cells secrete chemicals into the blood stream where they may travel to distant target cells
12
Q
- A single chemical messenger can have different mediatory functions?
A
yes: example: glucagon
glucagon involved in endocrine, paracrine and autocrine mediation
13
Q
briefly explain how the chemical messenger glucagon is involved in endocrine, paracrine and autocrine mediation
A
1) Endocrine: Glucagon secreted from a-cells in the islets of Langerhans (in pancreas) and are released into blood stream -> travel to liver (ultimately raise glucose level in blood)
2) Paracrine: glucagon released from a-cells, can act on nearby b-cells (that produce insuline) and delta cells (that produce somatostatin)
3) autocrine signalling: glucagon binds to glucagon receptors on the same a cell
14
Q
Endocrine cells:
A
secrete chemicals into the blood- stream, where they may travel to distant target cells.
15
Q
exocrine cell
A
A gland that has a duct through which its product is secreted into adjacent organs or the environment.
16
Q
pancreas is an example of being both an: __ and __
A
pancreas is an example of being both an exocrine and endocrine gland
exocrine function: release digestive juices in duct
endocrine: islets of langerhans (contain alpha, beta and delta cells that secrete glucahon, insulin and somatostatin)
17
Q
General features of the endocrine system (5);
A
(1) endocrine glands are ductless
(2) they have a rich blood supply
(3) hormones are secreted into bloodstream
(4) can reach all cells in body and may interact with cells with appropriate receptor
(5) hormone receptors are specific binding sites that interact with a specific hormone or a class of hormones
18
Q
Adipose Tissue as an Endocrine Organ
A
does not neatly fit the classical criteria of endocrine glands (the five aforementioned characteristics)
Not organized into discrete ductless glands, but rather composed of widely distributed cells.
Still has endocrine function: secretes hormones (also called adipokines)
19
Q
Major Endocrine Structure (8):
A
(1) hypothalamus
(2) pineal gland
(3) pituitary gland
(4) thyroid (growth and development metabolic rate)
(5) adrenal glands (adrenal cortex + medulla)
20
Q
Describe the main functions regulated by secretion of hypothalamus as a major endocrine structure
A
control of hormone secretions
the hypothalamus produces releasing hormones + oxytocin and ADH (vassopressin) that are released in the posterior pituitary
21
Q
Describe the main functions regulated by secretion of pineal gland as a major endocrine structure
A
-reproductive maturation:body rythms
-serotonin (transformed into melatonin)
-pineal in non mammals: circadian
-pineal in mammals: circannual
22
Q
How many hormones are produced in posterior pituitary?
A
none
23
Q
Oxytocin
A
uterine contractions during labour
milk ejection during breastfeeding
24
Q
Vasopressin (ADH)
A
water balance
salt balance
25
Posterior Pituitary: The posterior pituitary does not synthesize hormones. Instead, it contains the axon terminals of neurosecretory cells whose cell bodies reside in the hypothalamus. Hormones such as __ and __ are synthesized in the hypothalamus and transported down these axons to be stored and released into the bloodstream at the posterior pituitary.
oxytocin and vassopressin
26
Describe the main functions regulated by secretion of anterior pituitary as a major endocrine structure
Anterior pituitary receives signal from hypothalamus: those signals lead to anterior pituitary (anterior pituitary contains endocrine cell that release hormones into blood system) hormones released from anterior pituitary have various targets in body:
thyroid
adrenal cortex, and gonads: growth
27
Describe the main functions regulated by secretion of posterior pituitary as a major endocrine structure
vassopressin (ADH): water balance: salt balance
28
Describe the main functions regulated by secretion of thyroid as a major endocrine structure
growth and development: metabolic rate
29
Describe the main functions regulated by secretion of adrenal cortex as a major endocrine structure
salt and carbohydrate metabolism: inflammatory reactions
30
Describe the main functions regulated by secretion of adrenal medulla as a major endocrine structure
emotional arousal
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the adrenal medulla is under the control of:
sympathetic nervous system
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Describe the main functions regulated by secretion of pancreas (islets of langerhans) as a major endocrine structure
sugar metabolism
33
Describe the main functions regulated by secretion of gut as a major endocrine structure
(CCK: satiation, grehlin: hunger)
digestion and appetite control
(also involved in emotions we wouldnt reflexively think about)
34
Describe the main functions regulated by secretion of gonads (testes/ovaries) as a major endocrine structure
body development: maintenance of reproductive organs in adults
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Transient Endocrine Organ:
The placenta functions as a temporary endocrine organ during pregnancy. It produces several hormones essential for supporting fetal development and maintaining gestation. For example, progesterone is secreted by the placenta to: maintain endometrial lining
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hypothalamus located at __ of brain
base
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hypothalamus consists of:
nuclei
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In the central nervous system (CNS), a nucleus refers to
a cluster of neuronal cell bodies.
The equivalent structure in the peripheral nervous system (PNS) is called a ganglion.
These clusters often share common functions and projections.
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A type of hypothalamic nucleus: suprachiasmatic Nucleus (SCN):
Regulates circadian rhythms by responding to light input from the retina.
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A type of hypothalamic nucleus: arceate nucleus
Involved in energy balance, appetite regulation, and metabolic control; integrates signals related to eating, fasting, and exercise.
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A type of hypothalamic nucleus: ventromedial nucleus (VMN)
Plays a role in female reproductive behavior
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* Neurosecretory (or neuroendocrine) cells are
neurons that release neurohormones into the blood
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neuroendocrine communication: integrate __ and __ physiological processes via neurosecretory cells
Integrate neural info and coordinate physiological processes via neurosecretory cells
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describe neuroendocrine communication
*Signal Origin: Begins with an electrical or synaptic signal in the central nervous system (usually the hypothalamus).
*Signal Conversion: Specialized neurosecretory cells convert the neural signal into a hormonal one.
*Hormone Release: These hormones, called neurohormones, are released into the bloodstream—either directly (e.g., into the posterior pituitary) or via a portal system (e.g., into the anterior pituitary).
*Target Tissues: Neurohormones travel through the blood to act on distant endocrine glands or tissues, modulating a wide range of bodily functions such as metabolism, growth, stress response, and reproduction.
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link between kisspeptin and GnRH
Kisspeptin is a key upstream regulator of GnRH (Gonadotropin-Releasing Hormone).
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hypothalamus releasing hormones (5):
1. Corticotropin-Releasing Hormone (CRH)
2. Thyrotropin-Releasing Hormone (TRH)
3. Gonadotropin-Releasing Hormone (GnRH) - kisspeptin
4.Growth Hormone-Releasing Hormone (GHRH or somatocrinin)
5. Prolactin-Releasing Peptide (PrRP)
"Cool Teachers Get good pay
47
hypothalamic inhibiting hormones (3):
Girls put Goggles
1. Gonadotropin Inhibitory Hormone (GnIH) ** KISSPEPTIN
2. Prolactin-Inhibitory Hormone (PIH, e.g., dopamine)
3. Growth Hormone-Inhibiting Hormone (GHIH or somatostatin)
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one of the most regulated glands in the
endocrine system
Pituitary
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Anterior Pituitary
Tropic Hormones (6):
"A Tiny Little Frog Plays Guitar"
1. CRH → Adrenocorticotropic Hormone (ACTH)
2. TRH → Thyroid-Stimulating Hormone (TSH)
3. GnRH → Luteinizing Hormone (LH)
→ Follicle-Stimulating Hormone (FSH)
4. PrRP → Prolactin
5. GHRH → Growth Hormone
50
aldosterone (a mineral corticoid) function:
Regulates electrolyte balance and blood pressure
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Adrenal cortex divided into three
(1) zona glomerulosa (mineralcorticoids: aldosterone)
(2) zona fasciculata (gluccocorticoids: cortisol)
(3) zona reticularis
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Zona reticularis
endocrine cells that produce sex steroids (androgens)
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Zona fasciculata: key facts (location, primary hormone produced, hormone class, main function)
glucocorticoids (cortisol) important in stress response
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Zona reticularis: key facts (location, primary hormone produced, hormone class, main function)
Location: Innermost layer of the adrenal cortex (just above the adrenal medulla).
Primary Hormones Produced: Androgens, mainly DHEA (dehydroepiandrosterone) and androstenedione.
Hormone Class: Gonadocorticoids
55
Zona glomerulosa: key facts (location, primary hormone produced, hormone class, main function)
Location: Outermost layer of the adrenal cortex (just beneath the adrenal capsule).
Primary Hormone Produced: Aldosterone
Hormone Class: Mineralocorticoid
Main Function: Regulation of salt (sodium) and water balance, thereby influencing blood pressure.
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zona fasciculata
Location: Middle layer of the adrenal cortex.
Primary Hormone Produced: Cortisol (in humans)
Hormone Class: Glucocorticoid
Main Functions: glucose metabolism and stress response
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adrenal cortez affected by __, adrenal medulla affected by __
Adrenal cortex affected by adrenocorticotropin hormone
Adrenal medulla affected by sympathetic nervous system
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adrenal medulla produces what two hormones
epinephrine and norepinephrine
59
what is the structure of the thyroid gland
composed of spherical structures called follicles
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what are the functions (3) of the follicles in the thyroid?
synthesize, store, and secrete thyroid hormone
61
example of a thyroid hormone
Thyroxine T4
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thyroid releases thyroid hormone in response to:
TSH
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thyroid hormone have 3 general effects in mammals:
* affect metabolism
* alter growth and differentiation
* influence reproduction
64
what is special about the thyroid as an endocrine gland vs other endocrine glands
Stores large quantities of thyroid hormones
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__ have been show to disrupt thyroid hormone production
pesticides
66
Parathyroid glands:
separate from thyroid gland: produces parathyroid hormones: these are not impacted by the tropic hormone TSH
67
parathyroid gland start producing parathyroid hormone as a result of
detecting low calcium level in blood
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when there is not enough calcium in blood: parathyroid gland produce parathyroid hormone which:
demineralized bone to increase calcium level in bone
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The gonads are impacted by __ and __
FSH and LH
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The gonads have 2 functions:
* production of gametes
* production of hormones
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Functions of gonads are regulated by
gonadotropins
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gonadotropins
FSH and LH
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In gonads: the production of gamete mainly under control of
FSH
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In gonads: production of hormone mainly under control of :
LH
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Gonads : testes: seminiferous tubule contain:
specific type of endocrine cells called sertoli cells
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Sertoli cells:
provide nourishment to sperm
produce hormones
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gonads:testes: leydig cells:
important in production of hormones specifically ANDROGENS
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primary type of hormone produced by leydig cells
androgens
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where are leydig cells positioned compared to seminiferous tubules?
Leydig cells are OUTSIDE seminiferous tubules
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Gonads: Ovaries involved in (2)
-Cyclic changes in gamete and hormone production
NOT in gamete production (you are born with your gametes)
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Gonads: Ovaries: gamete released at
ovulation
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three functional subunits of ovaries:
(1) follicles (each contain developing oocyte/egg)
(2) corpus lutea (develop from follicles after ovum released)
(3) stroma (supporting tissue)
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ovum
mature female gamete
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gonads: ovaries: follicles:
Each follicle contains a developing oocyte (egg)
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gonads: ovaries: corpora lutea (singular corpus luteum)
Forms from the remnants of the follicle after ovulation (after ovum released)
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gonads: ovaries: stroma:
supporting tissue
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Theca cells produce
ANDROGENS
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Granulosa cells produce (2):
(1) ESTROGEN (from androgens)
(2) Progesterone (near ovulation these cells also produce progesterone
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Located in the outer layer of developing follicles.
Theca cells:
90
Surround the developing oocyte within the follicle.
Granulosa cells:
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Corpus luteum produces progestins, but also
estrogens
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gonads: ovaries: lh binds to:
receptor on theca cells
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gonads: ovaries: follicle stimulating hormone binds to its receptor on:
granulosa cells
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Oxytocin from posterior pituitary important in (2):
* Important during birth (involved in uterine contractions)
* Suckling reflex (release milk)
*Oxytocin also involved in overall bonding
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explain why ADH has different names: vassopressin and antidiuretic hormone
has different names because it does different things, vasopressin important in vasoconstriction (when vasoconstricted, blood pressure increases).
Also important in retaining urine (explains other name antidiuretic other name), ** important in regards to fluid regulation
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Vasopressin/Antidiuretic hormone (ADH)/Arginine vasopressin (AVP) important in (2):
(1) retain water
(2)hypertensive effects durinh serious blood loss
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In mammals, the pineal gland mainly plays a role in
circannual rhythms
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In mammals, __ is the master clock for circadian rhythm
superchiasmatic nucleus
99
In NON-mammals, cells in pineal gland are
photosensitive (which is why pineal gland receives term third eye)
100
pineal gland in non-mammals is involved in
circadian and circannual rhythms
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PANCREAS
* Both endocrine and exocrine gland. Why?
* Most cells produce and secrete digestive juices into intestines
* Islet of Langerhans secrete hormones
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* In mammals, the islets of Langerhans are innervated by
changes in blood glucose levels and by the vagus nerve
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Insulin acts on __ by __
Insulin acts on liver by promoting energy storage in the form of glycogen
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Glucagon released from ⍺-cells travels first to
liver
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* Somatostatin (growth hormone inhibiting hormone) released from δ-cells
inhibits the release of insulin and glucagon
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two important hormones from gastrointestinal tract
Ghrelin
Cholecystokinin
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in the gastrointestinal tract, the endocrine cells are __ (position)
scattered throughout the gut
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gastrointestinal tract: grehlin is made in:
endocrine cells in the STOMACH
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a type of chemical messenger made in endocrine cells in stomach:
grehlin
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Cholectoskinin (CCK) released by __
lining of SMALL INTESTINE
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most common class of hormone in vertebrates:
protein and peptide hormones
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Releasing hormones are typically
peptide hormones
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Tropic hormones are typically
protein hormones
**adrenocorticotropic hormone is smaller
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Shorter 50 amino acids =
peptide hormone
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protein and peptide hormones are stored in:
endocrine cells
*protein and peptide hormones are hydrophilic = love water = can be stored in vesicles in cells because they wont pass through cell membrane
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are protein and peptide hormones soluble in blood?
yes - protein and peptide hormones are hydrophilic
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do protein and peptide hormones need carrier proteins?
no carrier proteins necessary
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what will protein and peptide hormones do to slow their breakdown?
they will bind with other plasma proteins
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how are protein and peptide hormones removed (2):
degradation
excretion
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the half life is longer for protein or peptide hormones?
half life longer for larger protein hormones
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protein and peptide hormone receptors are where?
embedded in cell membrane
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protein and peptide hormone receptors have at least __
3 domains
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steroid hormones textbook definition:
A class of structurally related fat-soluble
chemicals that are derived from cholesterol and are character- ized by three six-carbon rings plus one conjugated five-carbon ring.
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Vertebrate steroid hormones have a characteristic chemical structure that includes
three six-carbon rings plus one conjugated five-carbon ring.
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Precursor to all vertebrate steroid hormones is
cholesterol
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solubility steroid hormones?
* Fat soluble
hydrophobic/ lipophilicNot very soluble in water
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where are steroid hormones stored?
they are never stored: they are lipophilic and thus will difffuse across membranes
Consequently, steroid hormones are never stored but leave the cells in which they were produced almost immediately.
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signal to produce steroids is
slow
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Explain how the solubility of steroid hormones impacts their transport:
steroid hormones are not very soluble in water so bind to water soluble carrier proteins
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describe the receptors of steroid hormones?
the target tissues of steroid hormones have CYTOPLASMIC RECEPTORS
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what kind of receptors can steroid hormones have?
can have receptors on membrane or in membrane
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each protein
hormone receptor comprises:
3 domains
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Factors that determine action of steroid hormones (3):
1) Concentration of steroid hormone in blood (a) rate of steroid biosynthesis, (b)rate of steroid inactivation (catabolism), (c) strength of binding with carrier protein
2)number of available receptors on target
3) availability of appropriate coactivators
134
one of the factors that affect the action of steroid hormones is their concentration in the blood (factor1/3). concentration of steroid hormone in blood depends on (3):
1. rate of steroid biosynthesis
2. rate of steroid inactivation
3.strength of binding with carrier protein
(which influences how much free (bioactive) hormone is available versus how much is bound and inactive)
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steroid hormone receptors are generally located __, the steroid hormone binds to its receptor to form a __, which __ to __
Steroid hormone receptors are generally located in the CYTOSOL or NUCLEUS of a cell. The steroid hormone (S) binds to its receptor (R) to form a HORMONE RECEPTOR COMPLEX (TRANSCRIPTION FACTOR), which binds to a hormone response ele- ment (HRE) on the DNA to begin transcription of mRNA.
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precursor to all steroid hormones (prohormone).
* Pregnenolone
137
pregnenolone is a prohormone and the precursor of all steroid hormones, it can be converted into:
progesterone, which is also a prohormone
138
enzyme desmolase:
cleaves cholesterol molecule to form pregnolone - a steroid prohormone that is obligate precursor of all other steroid hormones
| cholesterol->desmolase->pregnolone->progesterone
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glucocorticoids
One of the two types of corticoids secreted from the adrenal cortices:often
released in response to stressful stimuli.
140
mineralocorticoids
One of the two types of corticoids secreted from the adrenal cortices; important in ion exchange and water metabolism.
141
cortisol
The principal glucocorticoid produced in the adrenal cortices of primates, including humans.
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enzyme (other than desmolase) important for both mineral corticoid (aldosterone) and glucocorticoid (cortisol)
21 hydroxylase
cortisol needs 17 hydroxylase as well
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androgens can be produced (2)
(1) gonads ovaries/testes (mainly)
(2) adrenal cortex
144
aldosterone
A mineralocorticoid that causes the kidneys to retain sodium.
145
androgens
The primary steroi- dal product secreted from the testes.
146
**Testosterone and androstenedione
two important androgens produced in male gonads
147
IS progesterone necessary for production of androgens (testosterone + androstenedione) in male gonads?
no : two pathways possible from pregnenolone: one involves progesterone, one does not
148
which cells produce testosterone in testes
leydig cell (if the necessary enzymes and precursors are there: if cholesterol, desmolase and pregnolenone)
149
precursors of all estrogens
androgens
150
aromatization
The process of converting an androgen molecule to an estrogen molecule via the enzyme aromatase.
androgen -> estrogen via Aromatase
151
In ovaries, androgens converted
estrogens
152
aromatization
Specific enzymes convert testosterone and androstenedione → estrogens
153
sex hormones in gonads under control of:
FSH and LH
154
sex hormones in adrenal cortez under control of:
ACTH
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which two zonas in the adrenal cortex are most impacted by ACTH
zona fasciculata and zona reticularis
156
monoamine hormones are derived from:
single amino acid
157
what are the two main classes of monoamine hormones?
catecholamines and indoleamines
158
what is the precursor for catecholamine
tyrosine
159
what is the precursor for indoleamines
tryptophan
160
Adrenal medulla is main source of two catecholamines (1/2 monoamines)
epinephrine and norepinephrine
*also dopamine but less important hormonal effect
161
catecholamine ( a type of monoamine) hormones released into general circulation in response to
sympathetic activation aka fight or flight (NOT under ACTH control)
162
Indoleamines Precursor
tryptophan
163
catecholamines
Hormones that are derived from tyrosine and secreted primarily from the adrenal medulla.
164
indoleamines
Any of various indole derivatives, such as serotonin
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A catecholamine produced in the adrenal medulla that increases cardiac tone and glucose levels.
epinephrine
166
serotonin
A neurotransmitter formed from tryptophan; the precursor to melatonin forma- tion in the pineal gland.
167
melatonin
An indoleamine hormone released by the pineal gland.
168
Within pineal gland: serotonin transformed to
melatonin
169
Serotonin is prohormone to
melatonin
tryptophan->serotonin->melatonin
170
In all species, melatonin made at
night
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HOW ARE EFFECTS OF HORMONES REGULATED (5) ?
(1/5) By the physiological by-products resulting from their actions
(2/5) By the stimulatory or inhibitory effects of hormones (by the hormone itself)
(3/5) Via pulsatile secretion
(4/5) By receptor regulation
(5/5) By the environment
172
give 2 examples of the effects of hormones being regulated(1/5) By the physiological by-products resulting from their actions
(1) parathyroid hormone and calcium levels
(2) insulin and glucose
173
give an example of positive feedback
baby feeding- oxytocin released -> leads to milk release -> babies continue to suckle
174
give example of hormone effects being regulated via pulsatile secretion
* Hormones often released in spurts (episodic/pulsatile secretion)
* Ex: GnRh in rhesus monkeys
GnRH: released by neurosecretory cells in hypo, travel through portal system to anterior: whether gnRH arrives in high freq or low freq has impact on whether lh or fsh will be produced by cells in the anterior pituitary
* This pulsatile release has functional implications
* Chronic high levels→no receptor available, so no further physiological response
175
receptor regulation: more receptors available through:
exocytosis
176
receptor regulation: less receptors available through __
endocytosis
177
Define and give example of homospecific priming (receptor regulation)
Homospecific: same hormone is having an impact on downregulation/upregulation of its own receptors (estrogen can have impact on whether there are more estrogen receptors available)
178
define and give example of heterospecific priming
One hormone has impact on receptor for another hromoen( ex: estrogen in specific brain regions by bindin to its receptor leads to uoregulation of receptor for progesterone)
179
give example of hormone effects being regulated by the environment
Shorter days: nights bigger: more melatonin produced: system is informed
Longer days: shorter nights: less melatonin produced: tells organisms things that are associated with its reproductive behaviour
