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208 Cards in this Set

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What are the fourchemical messengers that cells use to communicate with eachother?
endocrine, paracrine, direct, synaptic
What are the 5 types of extracellular signaling?
1. contact dependent
2. paracrine
3. autocrine
4. synaptic
5. endocrine
What occurse in contact dependent signaling?
signal molecules remain bound to the signaling cell surface
How does paracrine signaling occur?
secreted as local mediators
What cells does paracrine signaling effect?
neighboring cells
What are autocrine signals secreted as?
local mediators
What cells does autocrine signaling effect?
the secreting cell
What occurs at synaptic signaling?
neurotransmitters are transmitted across the synaptic cleft
How does endocrine signaling work?
secreted into the blood stream
What cells does endocrine signaling effect?
distant targets
Compare endocrine signaling to neuronal signaling.
endocrine is slower but just as specific; the only cells that respond are the ones that recieved the message
How does endocrine system achieve homeostatic balance?
through communication
How is the endocrine system turned off?
negative feedback system
What are the three groups that hormones and paracrine factors of the body can be divided into?
1. amino acid derivatives
2. peptide hormones
3. lipid derivatives
What is the difference between a polypeptide and protein hormone?
a polypeptide hormone has less than 100 amino acids; protein hormone has more than 100
What are polypeptide and protein hormones synthesized on?
the rough endoplasmic reticulum of endocrine cells
What does the amino acid group consist of?
1. thyroid hormones
2. epinephrine, norepinephrine, dopamine
3. melatonin
What is a prohormone?
what is sent to the Golgi Apparatus, smaller, biologically inactive
What is a preprohormone?
Larger than a prohormone, biologically inactive
Where are hormone receptors located?
in the plasma membrane or inside the cell
Does the hormone have a direct effect on activities under way inside the cell?
NO
How does a hormone effect activies in the cell?
the hormone (first messenger) uses an intracellular intermediary (second messenger) to exert the hormones effects in the cytoplasm
What are the three things the second messenger can act as?
enzyme activator, inhibitor, cofactor
What are the two most important second messengers?
cyclic-AMP and calcium ions
What does the link between the first messenger and second messenger usually involve?
G protein
What are the two possible effects of cAMP levels rising
enzymes are activated or ion channels may be opened
What has an inhibitory effect on cells?
G protein activation resulting in decreased levels of cAMP in the cytoplasm
How do steroid hormones effect a cell?
diffuse across the phospholipid bilayer of teh plasma membrane and bind to receptors in the cytoplasm or nucleus
What are steroid hormones stimulated from?
cholesterol stored in vacules
What are amine hormones derived from?
tyrosine
What are amine hormones formed by?
enzymatic action in cytoplasmic compartments of glandular cells
Where are amine hormones stored?
in the cells (follicles or vesicles)
Are amine hormones lipid or water soluble?
both
How are amine hormones distributed?
diffusion for lipid soluble; exocytosis for water soluble
Where are polypeptide and protein hormones?
biologically active hormones stored in vesicles within the cytoplasm
What is the controlled variable with negative feedback control?
the degree of activity of the target tissue, not how much hormone is secreted
How are water soluble hormones transported?
they are dissolved in plasma; they diffuse out of capillkaries into interstitial fluid to the target cells
How do steroid and thyroid hormones circulate?
bound to the plasma protiens because they cant travel through the blood
What are hormone receptors?
specific protein or glycoprotein receptors
What are the four ways hormone receptors decrease?
1. inactivation of receptor molecules or intracellular signaling molecules
2. temporary sequestration of receptor to inside
3. destruction of receptors by lysosomes
4. decreased production
How does hormone receptor number increase?
in response to deficiency
What 2 factors increase or decrease blood concentration?
rate of secretion and rate of removal (metabolic clearance rate)
How do you calculate the metabolic clearance rate?
the rate of dissapearance from plasma/concentration of hormones
What are the four ways hormones are cleared?
1. metabolic destruction by tissues
2. binding with tissues
3. excretion by the liver into bile
4. excretion by kidneys into urine
How are peptide hormones removed from the blood?
rapid enzymatic degradation and excretion
How are plasma bound hormones removed from the blood?
only 10% are unbound at a time; slower
Whath are the four possible outcomes when a cell recieves two hormones at the same time?
1. antagonistic
2. additive
3. permissive
4. integrative
What occurs in an antagonistic hormone interaction?
one hormone opposes the action of another
What occurs in a permissive hormone interaction?
actions of one hormone require simultaneous or recent exposure to a second hormone; a hormone has an action it performs well but performs it better in the presence of another
What occurs in a synergistic or additive hormone interaction?
the effects of the two hormones together is stronger than either alone
What occurs in an integrative effect?
hormones produce different but complementary effects in specific tissues and organs
How many organs are there whose primary function is endocrine?
seven
What are the seven hormones whose main function is endocrine activities?
-hypothalamus
-pituitary gland
-thyroid gland
-adrenal gland
-pacreas
-pineal gland
-parathyroid glands
What organs have secondary endocrine functions (5)
-heart
-thymus
-digestive tract
-kidneys
-gonads
What structure has the highest endocrine control?
the hypothalamus
What two hormones do hypothalamic neurons synthesize?
ADH and OXT; antidiuretic and oxytocin
What are regulatory hormones?
hormones that control endocrine cells in the pituitary gland
What do the regulatory hormones control in the pituitary gland?
the secretory activities of endocrine cells n the anterior lobe of the pituitary gland
The hypothalamus has autonomic centers that control endocrine cells in what part of the body?
adrenal medullae
What does the endocrine system include?
all cells and body tisssues that produce or secrete hormones and paracrine factors
What are endocrine cells?
glandular secretory cells that release their secretions into extracellular fluid
Do endocrine cells contain ducts?
no
What supplies blood to the adenohypophysis?
the hypophyseal portal system
What is the anterior lobe of the pituitary called?
adenohypophysis
What is the posterior lobe of the pituitary lobe called?
neurohypophysis
What functions do the hypothalamus and pituitary work together to perform?
regulate growth, development, metabolism, homeostatis
What are the three functions of the hypothalamus?
1. synthesize releasing and inhibiting hormones that control endocrine cells of the anterior pituitary
2. synthesizes ADH and OXT that are released by the posterior pituitary
3. contains autonomic centers that exert neural control over the adrenal medullae
At what part of the infundibulum do hypothalamic neurons release regulatory factors?
median eminence
Are the endotheliall cells permeable?
yes
What part of the posterior lobe of the pituitary gland makes ADH?
supraoptic nuclei
What part oof the posterior pituitary gland makes oxytocin?
paraventricular nuclei
Can the communication go both ways in the hypophyseal portal system?
NO
How is the hypophyseal portal system structured?
ccapillary network in the median eminence, portal veins, second capillary netowrk in anterior lbe
How are the regulatory hormones secretged at the hypothalamus transported to the anterior lobe of the pituitary gland?
hypophyseal portal system
What is the purpose of releasing hormones?
stimulate the synthesis and secretion of one or more hormones in at the anterior lobe
What is the purpose of inhibiting hormones?
prevent the synthesis and secretion of hormones from the anterior lobe
What are the two types of hypothalamic regulatory hormones?
releasing hormones; inhibiting hormones
What hormones are released by the adenohypophysis? (7)
-TSH (thyroid stimulating hormone)
-ACTH (adrenocorticotropic hormone
-FSH (gonadotropin)
-LH (gonadotropin)
-GH (growth hormone)
-PRL (prolactin)
-MSH (melanocyte stimulating hormone)
Does the adenohypophysis secrete the end hormone?
no
What hormones are secreted by the posterior lobe? (2)
ADH and OXT
-antidiuretic and oxytocin
What is the infundibulum?
funnel shaped stalk that connets the pituitary gland to the inferior surface of they hypothalamus
How many peptide hormones are released by the pituitary gland?
nine
What do the hormones released by the pituitary gland bind to?
-membrane receptors
-use cAMP as a second messenger
What are the hormones of the anterior lobe called?
tropic hormones
Why are the hormones in the anterior lobe called tropic hormones?
they "turn on" endocrine glands or support the functions of other organs
What does TSH target?
the thyroid gland where it triggers the release of thyroid hormones
What causes the release of TSH and where does it come from?
TRH (thyrotropin releasing hormone) and it comes from hypothalamus
What happens when there are high levels of T3 and T4?
the rates of TRH and TSH production decline-->negative feedback
What is ACTH release triggered by and where does it come from?
CRH (corticotropin releasing hormone) and it comes from the hypothalamus
What does ACTH stimulate the release of?
production and secretion of cortisol by the adrenal cortex that affect glucose metabolism
What type of feedback occurs from rising levels of CRH and ACTH?
negative feedback
What are FSH and Lh release triggered by and where does it come from?
GnRH (gonadotropin releasing hormone) from the hypothalamus
What is the role of FSH?
promotes ovarieal follicle development in females and stimulates estrogen secretion; sperm production in males
What happes to FSH from increasing levels of estrogen and testosterone?
negative feedack
What is the function of LH?
initiates ovulation, when present with FSH it stimulates estrogen secretion
What happens with increasing levels of estrogens, progestins, and androgens?
negative feedback
What does prolactin initiate?
lactation and mammary gland development
When does the hypothalamus make PRL or PIH?
any time when there are increased estrogen levels
What inhibits the production of prolactin?
PIH (prolactin inhibiting hormone)
During pregnancy,, what triggers the release of prolactin?
PRF
What does hypersecretion of prolactin cause in males?
erectile dysfunction
What does hypersecretion of prolactin cause in females?
galactorrhea (overproduction of milk) and amenorrhea (cessation of menstrual cycle)
Where is MSH released from in the anterior lobe?
the pars intermedia in development, children, and pregnant woemn
what is the role of MSH in adults?
unknown
What stimulates the release of MSH
excessive leves of CRH
What inhibits the release of MSH?
dopamine
What is the function of MSH?
stimulates melanocytes of the skin to increase their production in melanin
What is the function of growth hormone?
stimulates cell growth and reproduction by accelerating the rate of protein synthesis
What stimulates GH release?
GHRH from the hypothalamus
What does GH promote synthesis and secretion of?
somatomedins (IGF's)
increase growth rate (children)
maintain mass and repair (adults)
When does negative feedback of GH occur
via somatomedins which stimulate GHIH and inhibit GHRH
What cells are particularly sensitive to GH?
skeletal muscle cells and chondrocytes
What do IGF's do
cause cells to grow and multiply by incresing thier uptake of amino acids
What is protein sparing?
not using amino acids so we can use it to build cells
Where are GH receptors and what do they produce?
in the liver and they produce and secrete IGF
Does GH act locally?
yes
What type of function tdoes GH have?
autocrine function or paracrine function
What type of circulation and release does GH have?
circadian patter, cyclic release during sleep
What are the effects of IGF?
Increased growth rate of skeleton and skeletal muscles in childhood, in adulthood it performs muscle and bone mass maintenence because breakdown=production
What are the four metabolic effects of IGF?
-enhance lipolysis in adipose tissue (make energy from fat)\
-decrease glucose uptake by most body cells
-stimulates liver cells to elease glucose
-decrease ATP production from amino acids
What are symptoms of excess GH?
1. diabetagenic-symptoms of diabetes mellitus
2. ketosis-decrease in blood pH (very dangerous)
What is the major difference between the neurohypophysis and adenohypophysis?
the neurohypophysis does not synthesize its hormones
What stimulates oxytocin release?
mechanical stimulation of mammary glands, birthing process
What is the function of oxytocin?
stimulates smooth muscle contraction in the wall of the uterus and ejection of milk concentrations during sexual arousal and orgasm
What are the target tissues of oxytocin?
uterus and brests
What causes the release of ADH
variations in blood volume and blood osmotic pressure:
What are teh functions of ADH?
-decreases urine production
-decreases water loss via sweating
-increases blood pressure by arteriole constriction
What causes negative feedback of ADH?
low osmotic pressure of the blood or increased blood volume because it inhibits osmoreceptors
What inhibits secretion of ADH?
alcohol
What stimulates secretion of ADH?
pain, stress, trauma, anxiety, acetycholine, nicotine, morphine
What do high concentrations of ADH cause?
vasoconstriction of peripheral blood vessels that helps elevate blood pressure
What is hormone secretion typically controlled by?
negative feedback
What does the thyroid contain?
large numbers of thyroid molecules
What do follicle cells produce?
thyroglobulin
Thyroglobulin molecules contain what amino acid?
tyrosine
How are thyroid hormones synthesized?
1. iodide trapping (pumped into follicular cell)
2. oxidation of iodide; synthesis of TGB
3. iodination of tyrosine=colloid
4. pinocytosis of colloid
5. digestion of colloid
6. secretion of thyroid hormones (T3 and T4)
7. transport in the blood with use of transport proteins
Do T1 and T2 ever go to the blood?
no
What are the effects of thyroid hormones on peripheral tissues?
-elevated rates of oxygen and energy consumption
-increased heart rate and force of contraction: increased blood pressure
-increased sensitivity to sympathetic stimulation
-maintenance of normal sensitivity of respiratory centers to changes in oxygen and carbon dioxide concentrations
-stimulation of RBC formation and enhanced oxygen delivery
-enhance actions of catecholamines (E and NE)
-accelerate body growth (nervous/skeletal)
-essentail for development in fetal and neonatal brain
How does the thyroid hormone increase the BMR?
-increased metabolic rate of CHOs, fats, proteins
-increased ATP synthesis
-increased protein synthesis
-increased mitochondrial activity
-increased heat release
What happens when there is too much thyroid hormone?
-high BMR
-hyperactive ANS
-irritable
-heat intolerant
-CV/heart problems
-weight loss
What happens when there is not enough thyroid hormone?
-development/CNS (cretinism)
-low BMR
-listless/slow
-cold intolerant
-obesity
What are C cells?
parafollicular cells
What do C cells produce?
calcitonin
What is the role of calcitonin?
aids in the regulation of calcium ion concentrations in body fluids by decreasing blood calcium concentration when there are excess calcium ions in the extracellular fluid
-inhibits osteoclasts
-accelerates uptake of calcium and phosphates into bone extracellular matrix
-stimulates calcium and phosphate excretion by kidneys
In what phases of life is calcitonin important?
-childhood
-pregnancy
-starvation
In a normal healthy adult, what are the symptoms of too much or too little calcitonin?
no symptoms!
What conditions is calcitonin a valuable therapy for?
Paget disease-disorder in bone modeling
post menopausal osteoporosis
What is the primary regulator of calcium ion levels in body fluids?
parathyroid hormone
How many parathyroid glands are there altogether?
four
What do parathyroid cells produce?
parathyroid
What are the two types of cells in the parathyroid gland?
-parathyroid cells
-oxyphills
What are oxyphil cells?
possibly depleted chief cells that no longer make parathyroid hormone
What does parathyroid hormone control?
calcium concentration when the calcium cncentration of the blood falls below normal
What is the specific action of the parathyroid hormone?
increased number and activity of osteoclasts
What is the effect of parathyroid hormone on the kidneys?
-slows the rate of calcium loss
-increased excretion of HPO4
-promotes formation of calcitrol (active form of vit. D)
What is the effect of parathyroid hormone on the GI tract?
increased rate of calcium and magnesium absorption from the GI tract into the blood
What occurs with hypoparathyroidism?
-blood calcium deficiency
-results in spontaneous depolarization and tetany
What occurs with hyperparathyroidism?
-excess resorption of bone matrix
-causes:
-soft bones that are easily fractured
-kidney stones
-fatigue, personality changes, lethargy
-hardening of arteries by calcium deposit
Where is the adrenal gland located?
above the kidneys
Are the adrenal glands supplied with blood vessels?
yes
What type of hormones do adrenal glands produce?
metabolic regulation
Why does the adrenal cortex have a yellow color?
stored lipids like cholesterol and fattyacids
How many steroid hormones does the adrenal gland produce?
two dozen
What are the steroid hormones produced by the adrenal gland referred to as?
adreenocortical steroids or corticosterois
How do corticosteroids exert their effects?
determining which genes in th enucli of their target cells are transcribed and at what rate
Are corticosteroids vital?
YES, you will die unless they are administered
What are the three distnct regions of the adrenal cortex?
zona glomerulosa, zona fasciculata, zona reticularis
What types of hormones does the zona glomerulosa?
mineralocortioids
*mostly aldosterone
What are the targets of aldostreone?
kidneys
What does aldosterone do?
increase renal absorption of Na and water, accelerates urinary loss of potassium
How is mineralocorticoid secretion controlled?
activation of th eRAS and inhibited by hormones that oppse that system
What hormones are excreted by the zona fasciculata?
glucocorticoids
What do glucocortiocids affect?
glucose metabolism, increase rates of glucose and glycogen formation by the liver
-release amino acids from skeletal muscles
-lipids from adipose tissues
-promote lipid catabolism within peripheral cells
What does cortisol reducue?
inflammation
What are the targets of glucocorticoids?
most cells
What are the primary hormones of glucocorticoids?
cortisol or cortisone
How is glucocorticoid secretion regulated?
stimulated by ACTH
What hoormones are excreted by the zona reticularis?
androgens that may be converted to estrogens in the bloodstream
What hormones does the zona retucularis excrete?
androgens that are converted to estrogens in the bloodstream
What are the target cells of most androgens?
-skin
-bones
-other tissues
What is the purpose of androgens?
stimulates pubic hair development in boys and girls
What regulates excretion of androgens?
stimulated by ACTH
What hormones does the adrenal medulla secrete?
epinephrine and norepinephrine
What are the target cells of epinephrine and norepinephrine?
most cells
What is the effect of epinephrine and norepinephrine?
-increased cardiac activity
-blood pressure
-glycoge breakdown
-blood glucose levels
How is epinephrine and norepinephrine regulated?
stimulated by sympathetic preganglionic fib ers during sympathetic activation
What makes up 99 percent of the pancreas?
the exocrine pancreas
What are the ondocrine clusters known as?
or islets of Langerhans
What four cells are included in the pancreatic islets?
-delta cells
-F cells
-beta cells
-alpha cells
What hormone do alpha cells produce?
glucagon
How does glucagon work?
raises blood levels by increasing the rates of glycogen breakdown and glucose release by the liver
What do beta cells produce?
insulin
How does insulin function?
lowers blood glucose levels by increasing the rate of glucose uptake and utilization by cells, increases glycogen synthesis in skeletal muscles and the liver
What do delta cells produce?
peptide hormone that is like growth hormone inhibiting hormone
How does growth hormone inhibiting hormone work?
suppresses the release of glucagon and insulin by other islet cells and slows the rates of food absorpition and enzyme secretion along the digestive tract
What do F cells produce?
pancreatic polypeptide
How does pancreatic polypeptide work?
inhibits gallbladder contactions and rgulates the production of some pancreatic enzymes
What are the primary hormones responsible for regulation of blood glucose leels?
insulin and glucagon
What is secreted when the blood glucose levels rise?
insulin
What is secreted when the blood glucose levels decline?
glucagon is secreted
What are the steps taken when there are rising levels of blood gluose?
1. rising levels
2. beta cells secrete insulin
3. increased rate of glucose transport into otarget cells, increased rate of glucose utilization and ATP generation, increased conversion of glucose to glycogen, increased amino acid absorption and protein synthesis, increased triglyceride synthesis in adipose tissue
4. blood glucose levels decrease
What are normal blood glucose levels?
70-110 mg/dL
What steps are taken when the blood glucose levels are falling?
1. blood glucose levels fall
2. alpha cells secrete glucagon
3. increased breakdown of glycogen to glucose in liver and skeletal muscle, increased breakdown of fat to fatty acids, increased synthesis and release of glucose
4. blood glucose levels increase
Where is the pineal gland located?
the epithalamus
What cells does the pineal gland contain?
neurons, neuroglia, speecial secretory cells (pinealocytes)
What does the pineal gland secrete?
melanocytes
What affects the rate of melanin production?
collaterals from the visual pathways
What are the three functions of melatonin in humans?
1. inhibiting reproductive functions
2. protecting against tissue damage by free radicals
3. setting circadin rhythms