Chapter 16 (Lecture) Flashcards
2 major controlling systems of the body
nervous and endocrine system
differences between the nervous system and the endocrine system
nervous system acts very quickly to effect change
endocrine system works slowly
the nervous system and endocrine system are ________________ on one another for the regulation of bodily functions
interdependent
a chemical messenger produced in minute amounts by a collection of specialized epithelial cells and is secreted directly into the blood or extracellular fluid, and acts on specific tissues called target cells
hormones
from simple amino acids to complex proteins (AA, peptides, glycoproteins); thyroid, epinephrine, norepinephrine [small AA], insulin and glucagon [more complex protein hormones]
amino acid derivative hormones
- synthesized from cholesterol
- primary ones are sex hormones and adrenal cortex hormones
steroid hormones
- not “true hormones”
- leukotrienes and prostaglandins
- autocrine or paracrine substances
- synthesized from arachidonic acid
eicosanoids
the hormones or chemical signals that act as ligands and bind to the receptors present on the cells producing them
autocrine substances
a substance secreted by a cell and acting on adjacent cells
paracrine substance
how do hormones work
- bind with receptors at their targets
- only alter or influence activities of cells
- have different effects on different targets (antagonism)
what are typical cell responses to hormonal stimuli (6)
*opening or closing of ion channels
* stimulate enzyme synthesis within cells
* activates or deactivates enzymes within the cell
* can cause phosphorylation of enzymes within the cell
* mRNA synthesis and direct gene activation
* can influence or affect mitosis
what are the types of hormone receptors
- amino-acid based second messenger systems
- intracellular receptors
which type of hormone receptor is most common
amino acid-based second messenger systems
membrane proteins that span the lipid bilayer
integral proteins
membrane proteins found on the inner or outer surfaces
peripheral proteins
act mainly as cell identifiers
glycoproteins
connected via blood vessels to the hypothalamus
anterior pituitary gland
first step of the hypophyseal portal system
when appropriately stimulated, hypothalamic neurons secrete releasing and inhibiting hormones into the primary capillary plexus
second step of the hypophyseal portal system
hypothalamic hormones travel through the portal veins to the anterior pituitary where they stimulate or inhibit release of hormones from the anterior pituitary
third and final step of the hypophyseal portal system
anterior pituitary hormones are secreted into the secondary capillary plexus
a harmful (in most cases) mechanism in which any deviation from the set point is amplified (ex: childbirth)
positive feedback
a homeostatic mechanism in which the variable oscillates around some set.point, in which deviation is resisted or diminished
negative feedback
types of regulation of hormonal secretion
- humoral stimulus
- neural stimulus
- hormonal stimulus
capillary blood contains low concentration of calcium which stimulates secretion of parathyroid hormone (PTH) by parathyroid glands
humoral stimulus
preganglionic sympathetic fibers stimulate adrenal medulla cells to secrete catecholamines (epinephrine and norepinephrine)
neural stimulus
the hypothalamus secretes hormones that stimulate the anterior pituitary gland to secrete hormones that stimulate other endocrine glands to secrete hormones
hormonal stimulus
characteristics of hormonal integration at its target
- permissiveness
- synergism
- antagonism
one hormone cannot exert its full effects unless another hormone is present
permissiveness
when two or more hormones affect a target cell and their effects are amplified
synergism
when one hormone opposes the action of another
antagonism
what do long half lives do for the steroid hormone
- prevent excretion
- stimulate new protein formation
- steroid hormone effect is long lasting
act as channels for water soluble solutes; some are powered by ATP
channel proteins
acts as an enzyme when stimulated (ex: adenylate cyclase)
membrane protein enzymes
1st messenger is the hormone (ligand)
binding to receptor triggers activation of 2nd messengers in within the cell
receptor proteins
- typically amino acids, peptides, and proteins
- have short half lives and are excreted rapidly
- have large surges caused by 2nd messenger cascade effects
water soluble hormones
- water soluble
- bind to membrane bound receptors
- degraded easily by enzymes
- short half-lives
amino acid based hormones
- lipid soluble
- bind to intracellular receptors
- bind to plasma protein and levels remain constant over time
- long half-lives
steroid based hormones
makes a target cell more responsive to hormones over time
up regulation
hormones that act via cAMP mechanisms (8)
- epinephrine
- ACTH
- FSH
- LH
- glucagon
- PTH
- TSH
- Calcitonin
- hormone (first messenger) binds receptor
- receptor activates G protein
- G protein activates adenylate cyclase
- Adenylate cyclase converts ATP to cAMP
- cAMP activates protein kinases
second messenger process
what acts as the first messenger in second messenger mechanisms
hormone
true or false: hormones act over short distances
false
hormones act over long distances
the study of hormones and the endocrine organs
endocrinology
produce nonhormonal substances, such as sweat and saliva, and have ducts that carry thesse substances to a membrane surface
exocrine glands
- also called ductless glands, produce hormones and lack ducts
- release hormones into the surrounding tissue fluid, and typically have a rich vascular and lymphatic drainage that receives their hormones
endocrine gland
how are lipid-soluble hormones activate
direct gene activation
what are the steps in order of direct gene actvation
- the steroid hormone diffuses through the plasma membrane and binds an intracellular receptor
- the receptor-hormone complex enters the nucleus
- the receptor-hormone complex binds a specific DNA region
- binding intiates transcription of the gene to mRNA
- the mRNA directs protein synthesis
second messenger systems have a ____ effect inside of cells
cascade
only hormones with a corresponding shape will activate the receptors, meaning that the complex has a
high affinity
how do steroid hormones exert their action
by entering the nucleus of a cell and initiating or altering the expression of a gene
glands that secrete their products into surrounding tissue fluids are classified as
endocrine glands
glands that secrete onto a membrane surface are classified as
exocrine glands
amino-acid based hormones require…
require a receptor in the plasma membrane
changes typically produced by a hormonal stimulus
-alters plasma membrane permeability
-induces secretory activity
-activates or deactivates enzymes
thyroid hormone (a small iodinated amine) enters target cells in a manner similar to
steroid hormones because both diffuse easily into target cells
true or false: water-soluble hormones are inactivated and removed from the blood by the liver
false
the effect of a hormone on a target cell may be decreased by the presence of
antagonistic hormones
true or false: steroid hormones are synthesized from amino acids
false
true or false: epinephrine is a steroid based hormone
false
which hormone can act on receptors inside target cells that directly activate activate specific genes
testosterone
phospho-
phosphate or phosphorus
-tropic
attracted specifically to the specified organ or tissue
angio-
blood or lymph vessels
-uria
urine
-phag-
feeding or eating
upon the release of renin, _________ is produced and stimulates vasoconstriction and the release of aldosterone
angiotensin II
enzyme that degrades second messengers like cAMP or cGMP
phosphodiesterase
overproduction of urine; a sign of diabetes mellitus
polyuria
overeating; a sign associated with diabetes mellitus
polyphagia
true or false: most type 2 diabetics do NOT produce insulin
false
normal development of the immune response is due in part to hormones produced by the
thymus gland
adult onset diabetes, diabetes type 2, can be best described as
constantly high blood sugar leads to high insulin release; high amounts of insulin lead to down-regulation of insulin receptors
which conditions stimulate the pancreas to release insulin
-a rise in blood glucose levels
-a rise in blood amino acid levels
-acetylcholine release on the pancreatic cells
what is a condition that triggers the release of glucagon
prolonged fasting
aldosterone functions to
increase sodium reabsorption
secretion of which hormone is increased in response to stress?
adrenocorticotropic hormone
which cellular organelle is the site of synthesis of amino acid-based hormones?
the ribosome
which cellular organelle is the site of synthesis of steroid hormones
smooth endoplasmic reticulum
how do glucocorticoids enable the body to deal appropriately with stress?
by increasing blood glucose, fatty acid, and amino acid levels and enhancing blood pressure
which condition would promote aldosterone release from the adrenal glands
a drop in blood pressure is sensed in the kidney
if a person’s parathyroids are responding properly to a drop in blood calcium, which of the following should result?
less calcium will be excreted in the urine by the kidneys
leads to reduced osteoclast activity in bones, increasing excitability of neurons and muscles, producing tingling sensations
hypoparathyroidism
what anterior pituitary hormone doesn’t target another endocrine gland?
growth hormone
hypersecretion of what hormone can produce the effects of gigantism
growth hormone (GH)
the single most important regulator of calcium levels in the blood is
parathyroid hormone (PTH)
iodized salt may be effective in preventing
congenital hypothyroidism, endemic goiter, and myxedema
true or false: oxytocin and ADH are produced in the posterior pituitary
false
stimulates the adrenal cortex to release corticosteroid hormones
adrenocorticotropic hormone (ACTH)
regulating hormones from the hypothalamus
first enter into the hypophyseal portal system
the various hormones secreted by the anterior pituitary that regulate the secretion of hormones from other endocrine organs are called
tropins
where is thyrotropin-releasing hormone (TRH) made
hypothalamus
determines whether a particular cell is able to respond to a hormone
the presence of a specific hormone receptor
the parathyroid glands respond to which type of stimulus?
humoral
which pancreatic hormone functions to raise blood glucose levels
glucagon
aids in water resorption
antidiuretic hormone (ADH)
a blow to the head may cause diabetes insipidus by
interfering with the normal transmission of nerve impulses to the posterior pituitary
the amplification of the signal from a water-soluble hormone is achieved through an increase in
cAMP in the cytoplasm
water-soluble hormones affect target cells by binding to
plasma membrane receptors
role of activated protein kinases
phosphorylate proteins
how do endocrine hormones reach their target cells?
hormones are transported through the blood stream to target cells
low blood glucose and high blood potassium concentrations are examples of what type of stimuli?
humoral
which organ in the body is considered to be a neuroendocrine organ?
hypothalamus
why are eicosanoids not considered to be true hormones
their effects are usually highly localized
which mechanism of hormonal action utilize intracellular calcium ions as a second messenger?
PIP2-calcium
chemical signals that act locally but affect cell types other than the releasing cells
paracrines
true or false: hormonal responses last longer than responses to nervous impulses
true
lipid-soluble hormones communicate with a target cell by
binding to receptors inside the cell
the transcription of new messenger RNA is a function of
steroid hormones
which gland/organ produces ACTH
anterior pituitary
what would cause a surge of prolactin (PRL)
a decrease in prolactin inhibiting hormone
the hypophyseal portal system transports releasing and inhibiting hormones from the hypothalamus to the
anterior pituitary
which hormone stimulates ovarian follicle maturation and sperm production?
FSH
mobilizes fats, spares glucose, and promotes protein synthesis
growth hormone
diabetes insipidus is caused by what homeostatic imbalance
hyposecretion of ADH
which hormone stimulates the production of FSH
GnRH
major function of growth hormone
causes cells to undergo mitosis and increase in size
ADH is secreted in response to what consitions
dehydration and low blood pressure
what is the function of adrenocorticotropic hormone
causes the adrenal cortex to produce hormones
releases neurohormones in response to nervous signals from the hypothalamus
posterior pituitary
steps to releasing anterior pituitary hormones
- when appropriately stimulated, hypothalamic neurons secrete releasing and inhibiting hormones into the primary capillary plexus
- hypothalamic hormones travel through the portal veins to the anterior pituitary where they stimulate or inhibit release of hormones from the anterior pituitary
- anterior pituitary hormones are secreted into the secondary capillary plexus
steps of releasing posterior pituitary hormones
- hypothalamic neurons synthesize oxytocin and ADH
- oxytocin and ADH are transported along the hypothalamic-hypophyseal tract to the posterior pituitary
- oxytocin and ADH are stored in axon terminals in the posterior pituitary
- oxytocin and ADH are released into the blood when hypothalamic neurons fire
one of the most metabolically active glands in the body
thyroid gland
steps to TH synthesis
-iodide is taken into the walls of the follicle and activated
-iodine is attached to the tyrosine in the lumen of the follicle
-T3 and T4 attached to thyroglobulin
-T3 and T4 detach and are secreted into capillaries
secretes thymosin; trophies as we grow older
thymus
decreases GnRH secretion by hypothalamus; secreted by the pineal body
melatonin
secretes melatonin, may or may not control the onset of puberty in humans
pineal body
important roles in the development in the development of the immune system early in the life of a newborn
thymosin
testosterone is secreted in response to
LH
estrogen and progesterone are secreted in response to
LH and FSH
structure: protein
target: most bodily tissues, but bones and muscles in particular
response: this is an anabolic hormone that causes an uptake for protein synthesis, growth in tissues, increased blood glucose levels
growth hormone (GH)
secretion of growth hormone is influenced by
GHRH and GHIH (somatostatin) from ventral nuclei of hypothalamus
structure: protein
target: mammary glands
response: stimulates mammary glands to produce milk around the time of birth
prolactin (PRL)
what is the secretion of prolactin controlled by
PIH (dopamine)
structure: glycoprotein
target: thyroid gland
response: increase thyroid hormone production
thyroid stimulating hormone (TSH)
secretion of TSH is controlled by
TRH
what is TSH a part of
the Hypothalamic-Thyroid (HPT) axis
structure: peptide
target: adrenal cortex
response: increased glucocorticoid hormone secretion
adrenocorticotropic hormone (ACTH)
secretion of ACTH is directed by release of
CRH
ACTH is derived from a molecule called
propriomelanocortin
ACTH is a part of which axis
HPA (hypothalamic-adrenal) axis
structure: glycoprotein
target: follicles in ovaries, seminiferous tubules
response: follicle maturation and estrogen secretion in ovaries, and sperm cell production in males
a gonadotropin
Follicle Stimulating Hormone (FSH)
structure: glycoprotein
target: ovaries and testes
response: ovulation and progesterone production in ovaries, testosterone synthesis and support
a gonadotropin
Lutenizing Hormone (LH)
secretion of Lutenizing Hormone (LH) is dependent on what hormone
GnRH
structure: small peptide
target: kidney
response: causes the nephrons to reabsorb water based upon the potency of the signal
a deficiency can lead to diabetes insipidus
antidiuretic hormone (ADH)
structure: small peptide
target: uterus and mammary glands
response: causes uterine contractions and milk ejection
acts in a positive feedback loop during labor
oxytocin
too much TH will inhibit the secretion of
TRH and TSH
too much cortisol will inhibit the secretion of
CRH and ACTH
high levels of sex hormones will inhibit the secretion of
GnRH and FSH/LH
the anterior surface of the thyroid gland secretes
TH and calcitonin
made up of T3 and T4
structure: amino acid
target: most cells in the body
response: increases basal metabolic rate, essential for normal growth
clinical: hypothyroidism and hyperthyroidism
thyroid hormone (TH)
produced by parafollicular cells
structure: polypeptide
target: bone
response: decreases osteoclast activity and increases the rate at which bone cells take up calcium–has a bone sparing effect
calcitonin
structure: peptide
target: bone, kidneys, small intestine
response: raise levels of blood calcium by breaking down bone, causes reabsorbtion of calcium by kidney, and causes intestines to absorb more calcium through the actions of vitamin D
parathyroid hormone (PTH)
controls nephrone tubule permeability and reabsorbs salts based on need, thus water will follow the salt back in by osmosis
structure: steroid
target: nephrons of kidney
response: sodium ion reabsorption and potassium ion secretion from the body
aldosterone (mineralcorticoids)
best known as cortisol
structure: steroid
target: most tissues in body
response: increase fat and protein breakdown for energy metabolism, incrase the synthesis of glucose in response to stressors, inhibit immune inflammatory response
a very important hormone for the function of many other organs and tissues throughout the body
glucocorticoids (cortisol)
too much cortisol
cushing’s disease and syndrome
too little cortisol
Addison’s disease
structure: steroid
target: many tissues
response: some secondary sex characteristics in females
androgens
strucure: amino acid
targets: heart, blood vessels, liver, fat cells
response: “fight or flight response”
epinephrine and norepinephrine
lowers blood glucose levels, part of the parasympathetic response after a meal when a lot of glucose is presence in the blood
structure: protein
target: most bodily cells, especially liver, skeletal muscle, and fat tissue
response: increases intake of glucose by cells
insulin
raises blood glucose levels
structure: protein
target: liver
responses: associated with sympathetic response to low levels of glucose in the blood; associated with sympathetic response to low levels of glucose in the blood; stimulates breakdown of glycogen stores into usable glucose that is then released into the blood
glucagon
estrogen and progesterone ares secreted in response to
LH and FSH
estrogen and progesterone are part of which axis
hypothalamic-gonodal (HPG) axis
testosterone is secreted in response to
LH
