Chapter 11 - Endocrine System Flashcards
What hormone(s) does adipose tissue primarily produce/secrete?
Leptin
What hormone(s) does the heart primarily produce/secrete?
atrial natriuretic factor
What hormone(s) does the liver primarily produce/secrete?
erythropoietin and IGF
What hormone(s) do the adrenal glands primarily produce/secrete?
steroids and catecholamine
What hormone(s) do the ovaries primarily produce/secrete?
Estrogen
What hormone(s) does the pineal gland primarily produce?
melatonin
What hormone(s) does the thyroid gland primarily produce?
thyroxin and calcitonin
What hormone(s) do the parathyroid glands primarily produce?
P.T.H.
What hormone(s) does the stomach primarily produce?
gastrin
What hormone(s) does the pancreas primarily produce?
insulin and glucagon
What hormone(s) do the kidneys primarily produce?
calcitriol and angiotensin II
What hormone(s) does the intestine primarily produce?
secretin
What hormone(s) do the testes primarily produce?
testosterone
Most endocrine cells are commonly derived from:
secretory epithelium
Define purely endocrine glands
compact, multicellular, ductless secretory glands that secrete chemical messengers into interstitial fluid and then diffuse into circulation.
General Properties of Hormones
- reg. of many physiological properties
- vary in chemical structure
- released in very LOW quantities (10^-11 M)
- movement solely through diffusion (& plasma)
- binding to receptors on target cells
- release in response to changes in homeostasis
Autocrine Effect
cell releases a chemical messenger onto itself
Paracrine Effect
cell releases chemical messenger into interstitial fluid onto neighbors
The same chemical can be categorized in more than one way depending on:
how it is released
ex. chemical from neuron can act as a hormone OR a neurotransmitter
norepi. is neurotransmitter when released onto neurons and a hormone when released into blood
Processes regulated by endocrine system:
- cellular metabolism
- tissue maturation
- blood levels of several critical ions + nutrients
- body’s fluid balance
- production of immune cells
- cardiovascular system
- reproduction, and parturition (birthing)
What type of feedback system is the endocrine system mainly regulated by?
Negative Feedback Loop
4 main types of hormones
- amino acid derivatives (amine)
- peptides
- proteins
- steroids
Explain hormone secretion in a negative feedback manner in a SIMPLE process
- stimulus
- endocrine cell
- effector hormone
- target cell
- response is blocked
Explain hormone secretion in a negative feedback manner in a COMPLEX process
- stimulus
- hypothalamus
- releasing hormone
- pituitary
- tropic hormone
- endocrine cell
- effector hormone
- target cell
- response is blocked
Target cells
cells that express a receptor
Downregulation
target cells remove receptors from the plasma membrane
no/little physiological response even if hormone is secreted
Upregulation
increasing the expression of receptors for a hormone
makes target cell more sensitive
What are the 2 mechanisms by which upregulation & downregulation occur?
- changing the rate of receptor synthesis or degradation
- transport to/removal from the plasma membrane or cell interior
Permissiveness
process of hormones regulating the expression of receptors for other hormones
Consequence of permissiveness
presence of one hormone is sometimes required for another hormone to have its full effect
ex. PTH has a permissive effect on Vitamin D3 absorption of calcium in small intestine
Hormone release is ____________ regulated in contrast to neurotransmitter release which is ____________ regulated
Hormone release is amplitude regulated in contrast to neurotransmitter release which is frequency regulated.
____ and ____ hormones are encoded by genes
peptide and protein hormones are encoded by genes
________ and_______________ are not encoded by genes.
steroids and amino acid derivatives are not encoded by genes.
How is the hormone epinephrine synthesized?
enzymatic synthesis
How is the hormone GH synthesized?
gene transcript
How is the hormone cortisol synthesized?
enzymatic synthesis
How is the hormone ACTH synthesized?
gene transcription
ACTH
adrenocorticotropin hormone
Hormone secretion is regulated in response to many basic processes:
- changes in a critical physiological factor (ex. ions)
- input from the nervous sytem directly through the release of neurohormones (ex. autonomic neurons)
- actions of other hormones (ex. hypothalamic regulation of the pituitary gland)
- mechanical stresses (heart atria) or cellular metabolism
Water-soluble hormones are usually transported direclty in the:
plasma
Lipid-soluble hormones and thyroxine are transported through:
blood complexed to transport proteins
exist in both free (much less; <1%) and bound forms (>99%)
Half-life
time required to reduce the blood concentration of the hormone by 50%
altered by rate of synthesis, secretion, metabolism, and excretion
Half-life
time required to reduce the blood concentration of the hormone by 50%
altered by rate of synthesis, secretion, metabolism, and excretion
Factors that increase half-life
- increased synthesis
- increased secretion
- binding to transport proteins
- modification of structure
- decreased metabolism
Factors that decrease half-life
- decreased synthesis
- decreased secretion
- excretion by kidneys or bile
- enzymatic degradation
- addition of a side chain
- reabsorption
Peptide and protein hormones degraded by ________ from the ________ and __________.
Peptide and protein hormones degraded by proteases from the liver and kidney.
____________can be rendered inactive by addition/removal of chemical groups.
steroids
can also change solubility
Common hormone receptor features:
- are proteins forund in cell membrane, cytoplasm, or nucleus
- change shape when bound by proteins
- intereact with other proteins inside cell, and by changing shape can activate signal cascades altering cell function
3 main types of hormone receptors:
- seven-transmembrane spanning G protein coupled receptors (GPCRs) (on cell membrane)
- one-transmembrane-spanning receptors (1-TMS) (on cell membrane)
- cytosolic/nuclear receptors (NR) (inside cell)
Pharmacologic effects of hormone receptors:
when hormones/drugs that mimic hormones are used and administered at high concentrations, they have side effects that are not physiological
Agonist:
compound that can bind to a hormone receptor and produce same effects as hormone
Antagonist
compound that binds to receptor and blocks signal transduction
G-protein coupled Receptors (GPCRs)
- 7-pass integral membrane proteins
- N-terminus exposed to E.C.F.
- C-terminus exposed to cell interior
One-transmembrane spanning receptors (1-TMS)
- directly activate enzymatic activities in cell membrane w/o G-proteins
- N-terminus exposed to ECF
- C-terminus exposed to cell interior
- ex. insulin receptor: receptor tyrosine kinase
Nuclear Receptors
- found inside cells
- act as transcription factors
- bind to steroids, thryoxine, and other ligands, and regulate cellular gene expression
- 4 classes
4 classes of nuclear receptors
Class I and II bind hormones
- Class I: nucleus; complexed to heat shock proteins —> homodimerization —> go to nucleus and reg. transcription
- Class II: found in nucleus complexed to co-repressor proteins; bind to thyroxine (receptors for androgen, estrogen, glucocorticoid, calcitriol, and progesterone)
Receptor for Grave’s disease
- aka hyperthyroidism
- thyroid stimulating hormone receptor
Receptor for Jansen’s metaphyseal chondrodysplasia
Parathyroid horomone receptor
Receptor for Ovarian dysgenesis type I
Follicle-stimulating hormone receptor
Receptor for Familial glucocorticoid deficiency
Melanocortin/adrenocorticotropic hormone receptor
Receptor for Familial male precocious puberty
Luteinizing hormone receptor
Receptor for Familial hypocalciuric hypercalcemia
antidiuretic hormone receptor
Receptor for gonadotropin-releasing hormone receptor
Hypogonadotropic hypogonadism
What are the 3 distinct nuclei of the hypothalamus?
- paraventricular
- Preoptic
- Supraoptic
Hypophyseal Portal System
- highly fenestrated
- does NOT have a blood brain barrier
- Primary capillary plexus: supplies blood to median eminence; blood drained through hypophyseal portal veins into secondary capillary bed in anterior pituitary
- Secondary capillary bed: drains into veins that carry blood out to body
Many of the hypothalamic hormones are ____ hormones
Many of the hypothalamic hormones are trophic hormones.
Trophic hormone
hormones that not only affect the release of other hormones, but also stimulate the growth and capacity for hormone relase by the tissue(s) that they affect.
Releasing hormones
hypothalamic hormones that stimulate the secretion of anterior pituitary hormones
Release inhibiting hormones
hypothalamic hormones that inhibit the secretion of anterior pituitary hormones
The hypothalamic hormone TRH affects which pituitary hormone?
TSH
The hypothalamic hormone PIH affects which pituitary hormone?
prolactin
The hypothalamic hormone GnRH affects which pituitary hormone?
LF/FSH
The hypothalamic hormone CRN affects which pituitary hormone?
ACTH
Effect of Thyrotropin-releasing hormone (TRH)
TSH and prolactin release
Effect of Corticotropin-releasing hormone (CRH)
ACTH release
Effect of Growth hormone-releasing hormone (GHRH)
GH release
Effect of Gonadotropin-releasing hormone (GnRH)
FSH and LH release
Effect of Prolactin-inhibitory hormone (PIH or dopamine)
Prolactin inhibition
Effect of Growth hormone - inhibitory hormone (GIRH, Somatostatin)
GH and TSH inhibition
Effect of Oxytocin
uterine contraction, socialization, lactation
Effect of antidiuretic hormone
increased renal collecting duct water permeability
Pituitary gland is composed of:
anterior, intermediate, and posterior lobes
Anterior lobe of Pituitary gland
-
adenohypophysis: arises embryonically from outpocketing of roof of embryonic oral cavity aka Rathke’s pouch
- subdivided into: parts tuberalis and pars distalis
- cell types: somatotropes, thyrotropes, corticotropes, lactotropes, and gonadotropes
Intermediate lobe of Pituitary gland
secretes melanocyte stimulating hormone (MSH)
Posterior lobe of Pituitary gland
- neuropophysis: arises embryonically from hypothalamus
- antidiuretic hormone: ADH/vasopressin (mammary glands/uterus) and oxytocin (kidneys)
Actions of Oxytocin
- milk ejection/letdown
- uterine contraction
- social behavior
- play a role in autism
Milk ejection/letdown
during lactation, oxytocin causes movement (“let down”) of mammary milk into subareolar sinuses —-> can be excreted from nipples.
- Oxytocin release activated by a parent seeing or hearing a hungry baby.
Uterine Contraction
oxytocin stimulates urine contraction during the second and thrid trimesters of pregnancy; contraction inhibited by elevated blood progesterone levels.
Social behavior
oxytocin evokes feelings of contentment, reduced anxiety, calmness and security in the company of a spouse of significant other.
Actions of ADH
- increases expression of aquaporin channels in nephrons of kidney, increased reabsorption of water into the plasma
- increased expression of urea transporters in collecting duct therefore increasing interstitial osmolarity gradient and water reasbsorption
- increased reabsorption of Na+ in loop of Henle, again increasing interstitial osmo. gradient
- at high concentrations, ADH is vasoconstrictor of blood vessels and increases B.P.
- plays role in aggression, BP, and body temp
Anterior Pituitary Gland Physiology
- hormones: proteins, glycoproteins, or polypeptides
- released into secondary capillary bed in ant. pituitary —–> released in general circulation
- have short half life in blood
- bind target cells in body - have tropic effects
Tropic Effects
stimulate release of other hormones, have direct effects on target tissues, and affet tissues that produce hormones
Growth Hromone
- released from anterior pituitary
- under reg. of hypothalamic GHRH and GHIH
