Endocrine Sytem Flashcards
What kind of messengers does the endocrine system send out?
hormones
Which system sends chemical messages for intercellular messages that stays from days to weeks?
endocrine
What kind of messengers does the nervous system send out?
action potentials and neurotransmitters
Which system send out chemical messages that last seconds to milliseconds?
nervous
Secretes products into ducts or lumens or to the outer surface of the body
Exocrine glands
Secretes products into interstitial fluid or blood
Endocrine glands
Chemical messengers (a.k.a mediator messengers) released in one part of the body and regulate activity. in other parts of the body
Hormones
Act locally on neighboring cells or on the same cell that secreted them WITHOUT first entering the blood stream
Local Hormones
IL‐2 released from helper
T cells stimulates
proliferation of helper T
cells and activation of
cytotoxic T cells is an example of a
Local Hormone
Histamine released by
mast cells stimulates HCl
secretion from parietal
cells in stomach is an example of a
Local Hormone
Which hormone can act as paracrine and autocrine at the same time?
IL-2
Enter ISF and then the bloodstream
Circulating Hormones
Bound to transport proteins for transport in body fluids
Lipid-Soluble Hormones
Freely dissolved in body fluids
Water-Soluble Hormones
Derived from Cholesterol
Steroid Hormones
Chemical groups attached ot structure’s core make it unique
Steroid Hormones
Cortisol, Testosterone, Progesterone, Estrogens. Aldosterone
Steroid Hormone
Tyrosine ring attached with iodines
Thyroid Hormone
Very lipid soluble
Thyroid Hormone
Chains of amino acids
Peptide and Protein Hormone
Hypothalamic releasing and inhibiting hormones
Peptide and Protein Hormone
ADH, Oxytocin, hGH, TSH, ACTH
Peptide and Protein Hormone
Insulin, Glucagon, EPO
Peptide and Protein Hormone
Modified amino acids
Biogenic amines
Catecholamines, NE, Epinephrine, Dopamine
Biogenic Amines
Serotonin, Melatonin, Histamine
Biogenic Amines
- Lipid-Soluble Hormone diffuses into cell
- Activated
receptor–hormone
complex alters gene
expression
3.Newly formed
mRNA directs
synthesis of
specific proteins
on ribosomes - New proteins alter
cell’s activity
Mechanism of Steroid Hormone
-Leave secretory cell
by diffusion
‐Require transport
proteins
‐Diffuse freely into
target cells
‐Receptors are
typically
intracellular
‐Work by changing
level of specific
gene expression
Steroid Hormone Action
The response by target cells to
steroid hormones is relatively
Slow
-Leave secretory cell by
exocytosis
‐Don’t require transport
proteins
‐Bind to cell surface receptors
‐Typically evoke changes in
activity of existing proteins
via second messengers
e.g. c‐AMP
‐Second messengers alter
phosphorylation state of
existing proteins
Peptide Hormone Action
The response by target cells to
water‐soluble hormones is
VERY very fast
- Binding of hormone (1st messenger) to its receptor activates a specific G protein, which activates adenylate cyclase
- Activated adenylate cyclase converts ATP to cAMP
- cAMP serves as a 2nd messenger to activate protein kinases
- Activated protein kinases phosphorylate cellular proteins
- Millions of phosphorylated proteins cause reactions that produce physiological responses
- Phospho‐diesterase inactivates cAMP
Peptide Action Hormone
Kinases ____ phosphates, phosphatases _____ them
adds, removes
Example of the same hormone may use different second messengers in
different target cells
Norephinephrine
Second messengers initiate ________________ reactions
(often involving phosphorylation or dephosphorylation) within target cells
a cascade of biochemical
Blood vessels are controlled by the _____ division of the ANS as well as by hormones such as ______.
sympathetic, angiotensin ll
__________ receives input
from cortex, thalamus, limbic
system & internal organs
Hypothalamus
________ provides a link
between the external and
internal environment and the
endocrine system
Hypothalamus
__________ and _______
together control almost all
aspects of growth,
development, metabolism,
and homeostasis
Hypothalamus, pituitary
A hormone that regulates the function
of endocrine cells or glands
Tropic Hormone
Example of a tier of tropic hormones
hypothalamus, pituitary gland, gonads
The hypothalamus controls the anterior pituitary gland with special hormones called ____________________ and
_______________
releasing hormones and inhibiting hormones.
The hypothalamus releases
other hormones directly
into circulation through the
Posterior pituitary
For the ____________, the hypothalamus makes the hormones. For the ____________, the hypothalamus controls it w/ releasing & inhibiting hormones
posterior pituitary, anterior pituitary
The hypothalamus can send motor
_________ to various tissue ________
(smooth muscle, glands, etc.)
impulses, effectors
The hypothalamus can make use of the
____________________________________ by
secreting ___________________________
endocrine system as an effector, releasing and/or inhibiting hormones (tropic hormones)
Releasing and inhibiting hormones act
on ______________________________
target cells in the anterior pituitary
_______________ secrete human Growth Hormone (hGH)
Somatotrophs
_________________ secrete Thyroid
Stimulating Hormone (TSH)
Thyrotrophs
________________ secrete Prolactin (PRL)
Lactotrophs
_______________ secrete Follicle
Stimulating Hormone (FSH) and
Lutenizing Hormone (LH)
Gonadotrophs
_______________________ secrete Adrenocorticotropic Hormone (ACTH) and Melanocyte Stimulating Hormone (MSH)
Corticotrophs
Anterior Pituitary is also
called the ______________
adenohypophysis
Posterior pituitary is also called the __________
neurohypophysis
- Does not synthesize hormones
- Consists of axon terminals from 2 groups of hypothalamic neurons
- These neurons release 2 peptide hormones that enter capillaries
Posterior Pituitary
resembles neural tissue; it has glial
cells, nerve fibers, nerve endings, and neurosecretory vesicles
Posterior Pituitary
Synthesized in supraoptic nucleus of hypothalamus in response to
signals from osmoreceptors which monitor blood hydration status
Antidiuretic Hormone (ADH)
Three main targets:
‐Kidney: Decreases diuresis (water loss) at kidneys, via increased water
reabsorption.
‐Sweat glands: Decreases water loss
‐Arterioles: Causes vasoconstriction (“vasopressin”)
ADH
Synthesized in paraventricular nucleus of the hypothalamus
Oxytocin (OT)
Two main targets:
– Uterus: during labor
– Mammary glands: after delivery
OT
Dehydration or high blood osmolarity
ADH released by posterior pituitary
Over-hydration or low blood osmolarity
ADH release inhibited
When drinking alcohol
ADH release inhibited
– Caused by lack of ADH or
nonfunctional ADH receptors
– Inability of kidneys to conserve H2 O
– Excessive urination
Diabetes insipidus
(lack of ADH) leads to an increase in urine output from 1‐2 L/day to 20 L/day. Treatment is replacement therapy (injection or nasal spray!)
Diabetes insipidus
Oxytocin’s role as an effector of _____________________ regulation: regulation of uterine contraction
during childbirth (labor)
Positive Feedback
Oxytocin’s role as an effector of ______________: regulation of mammary gland function after delivery
Negative Feedback Regulation
Within target cells hGH increases synthesis of__________ that act locally or enter bloodstream
insulin‐like growth factors
– increase cell growth and cell division by increasing the uptake of amino acids and synthesis of proteins
– stimulate lipolysis in adipose tissue (released fatty acids are used for ATP production in most body cells)
– decrease glucose use by most body cells so blood glucose levels remain high enough to supply the brain
Insulin-like growth factors
Stimuli for GHRH
Hypoglycemia, deep sleep, decreased fatty acids and increased amino acids in the blood, increased sympathetic stimulation
Stimuli for GHIH
Hyperglycemia, REM sleep, increased fatty acids and decreased amino acids in the blood, obesity, low levels of thyroid hormones, high levels of hGH
– stimulates secretion of estrogen
– initiates the formation of follicles within the ovary
FSH inn females
– stimulates sperm production in teste
FSH in males
from hypothalamus stimulates gonadotrophs in
anterior pituitary to produce LH
GnRH
– secretion of estrogen and progesterone
– ovulation
– formation of corpus luteum
LH in females
– secretion of testosterone
LH in males
Formation of Thyroid Hormones (T3 & T4)
- Iodide trapping by follicular cells
- Synthesis & release of thyroglobulin (TGB) into colloid
- Oxidation of iodide
- Iodination of TGB tyrosines in colloid
- Formation of T3 & T4 by combining T1 and T2 together
- Uptake & digestion of TGB by follicle cells
- Secretion (diffusion) of T3 & T4 into blood
- Binding and transport of T3 & T4 by thyroxine binding globulin (TBG)
Functions of Thyroid Hormones
Increase basal metabolic rate (BMR) by stimulating
the cellular use of O2 to produce ATP
increased cellular catabolism of glucose
(glycolysis), fatty acids (beta oxidation) and
triglycerides (lipolysis)
Increase synthesis of Na+/K+ ATPase
more ATP is used to pump ions
ATP use produces heat, which raises body
temperature
called the calorigenic effect
Enhance some actions of sympathetic nervous system
by up-regulating beta-receptors
increased heart rate, contractility &blood pressure
Stimulate growth* (in conjunction with hGH and
insulin), particularly during development
* primarily nervous system & skeletal system
- During development, infancy and/or early childhood:
results in dwarfism and severe mental retardation
(congenital hypothyroidism or cretinism) - In the adult:
results in edema, low heart rate, muscle weakness,
sensitivity to cold, low body temperature, weight
gain and mental dullness (myxedema)
Thyroid Gland Disorders - Hypo-secretion
weight loss, nervousness,
tremor, increased heart
rate and blood pressure ,
exophthalmos (edema
behind eyes), high body
temp, sweating indicates symptoms of
Hyperthyroidism (Graves’ disease)
Goiters…
occurs because TSH levels are high
stimulates growth of thyroid gland
* can be associated with hyperthyroidism,
hypothyroidism or euthyroidism
* dietary lack of iodine leads to low
thyroid hormone (T3/T4) production
stimulates TSH by negative feedback
stimulates thyroid gland growth
