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Adv Ex Phys (II) Exam 4
Endocrinology & Renal Physiology
45
Physiology
Undergraduate 4
08/01/2010

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Term
3 major categories of Hormones (and 2 minor classifications)
Definition
-Peptide hormones (proteins of varying size)
-Amino acid-derivitive hormones
-Steroid hormones

(biologically-active lipids and glycoproteins)
Term
What are the systems of action that hormones use?
Definition
-Endocrine: general release and action into circulation
-Paracrine: release and action nearby tissue
-Autocrine: release and action on same tissue
Term
Hormone effect on a target tissue is _____ _______ to the _______ of the hormone AND the __________ contained in the tissue/cell
Definition
directly related, concentration, receptor
Term
What are the hormone effects on target tissues?
Definition
-Modify amount of intracellular protines
--gene expression or protein synthesis

-Change rate of enzymatic activity

-Alter membrane transport

-Induce secretory activity
Term
Factors influencing homrone concentration:
Definition
-Rate of synthesis and/or secretioin from the endocrine gland
--pulsatile manner (diurinal)

-Rate of hormone metabolism/breakdown

-quantitiy of trnasport or binding proteins

-Plasma volume
Term
Factors influencing synthesis and/ or secretion
Definition
-hormonal, humoral, and neural
Term
2 Types of Hormone receptors:
Definition
1) INTRACELLULAR RECEPTORS
-Located: cytoplasm and/or nucleus
-H class: Steroid and thyroid H's
-Alter transcriptional activity of target genes

2)CELL SURFACE RECEPTORS
-Located: cell membrane
-H class: peptide hormones and catecholamines
-Generation of 2nd messengers which alter the activity of other molecules- usually enzymes w/in the cell
Term
Steroid Hormone signaling facts
Definition
Steroid hormones are fat soluble
-carrier proteints are needed to transport steroid hormones in the blood
-steroid hormones are membrane permeable b/c they are fat soluble
--diffuse into cell and bind to intracellular receptors
Term
Peptide hormone signaling facts
Definition
Peptide hormones are water soluble
-transported freely into blood
-sometimes bound to other proteins

Peptide hormones cannont enter cell b/c the membrane is made of lipids
-They bind to extracellular membrane receptor
-utilizes 2nd messenger system for inducing action
Term
3 major mechanistic categories
Definition
-substrate utilization
-tissue growth and repair
-fluid regulation
Term
3 major mechanistic categories
Definition
-substrate utilization
-tissue growth and repair
-fluid regulation
Term
Substrate utilization
Definition
-at rest: fat is predominate fuel
-w/ exercise: increasting utilization of CHO as fuel
-Glucose sources: blood, glycogen (muscle & liver)
(glycogenolysis, gluconeogenesis --> glycolysis/TCA cycle/ ETC)

Lipid Sources: adipose tissue, IM triglycerides
(lipolysis --> FFA --> Beta-oxidation/TCA cycle/ETC
Term
What hormones are responsible for eliciting substrate utilization responses to exercise?
Definition
-insuline and Glucagon, cortisol, epinephrine, and GH
Term
General effects of insulin and glucagon
Definition
INSULIN
-secreted by Beta cells of the pancreas
-in response to high plasma glucose concentrations
-responsible for the uptake and storage of glucose and ffa
-anabolic

GLUCAGON
-secreated by the Alpha cells of the pancreas
-in response to low plasma glucose concentrations
-responsible for the mobilization and availability of glucose and ffa
-catabolic
Term
Insulin and Glucagon's mechanisms of action
Definition
INSULIN
-peptide hormone released from B cells
-binds to insulin receptor
--cell membrane receptor
--activates MULTIPLE 2nd messengers b/c insulin does more than just glucose uptake

GLUCAGON
-peptide hormone thats released from alpha cells
-binds to glucagon receptor
-cell membrane receptor (cyclic AMP)
-activates multiple 2nd messenger systems
Term
What are the specific mechanisms of Insulin?
Definition
-Insulin primarily does UPTAKE and STORAGE and is stimulated by increase blood glucose

-Adipose tissue:
->stimulates FFA uptake
->Stimulates glucose uptake
->stimulates triglycerides synthesis (requires 3-C from glucose)

-Muscle & Liver
->stimulates glucose uptake
->stimulates glycogen synthesis via glycogen synthase.
Term
Specific mechanisms of Glucagon
Definition
-Glucagon is primarily responsible for mobilization and is stimulated by decreased blood glucose.
-it renews glucose from nonglycolytic sources

-Adipose:
->stimulates lipolysis which is the release of triglycerides and glycerol

-Liver
->stimulates glycogenolysis (via glycogen phosphorylase)
->stimulates gluconeogenesis from AA and glycerol
Term
What is Glucagon's specific mechanism in Muscle?
Definition
-Glucagon doesn't work in muscle b/c there is no receptor for it. Skeletal M is not glucagon's target tissue. The muscle is greedy and won't release its glucose stores.
Term
Explain the changes in glucose availability during exercise
Definition
-Blood glucose is maintained despite increased glucose uptake
-At higher intensity exercise, more glucose is needed. This is achieved via heptatic glucose production where glucose is released from liver
-this production of glucose causes an incresat in blood glucose concentrations.
-liver chills out on glucose synthesis causing uptake to exceed production. Body switches to utilizing lipids causing a drop in VO2
-exercise also stims epinephrine which stimulates liver to breakdown glycogen and release glucose.

-**epi inhibits the pancrease from releasing insulin during exercise because the body is fighting its natural response.
-Insulin stores glucose so by inhibiting it the body preserves glucose for exercising muscle.
Term
Brief summary of glucose availability during exercise
Definition
-Blood glucose concentrations are maintained at lower intensities of exercise
-as exercise intensity increase, so does glucose uptake and utilization
-but blood glucose does not decrease, it increases via hepatic glucose production
-Epinephrine stimulates glycogenolysis and gluconeogenesis in the liver
-->epinephrine release from adrenal medulla via SNS stimulation (amino acid derivative hormone)

-Epinephrine inhibits the release of Insulin
--> insulin can't stimulate glucose uptake into other tissues
-->this preserves glucose for increasing muscle uptakte

increase Epi:
-Adipose tissue: TG-> FFA-> increase plasma FFA
-Liver:
Glycogen->glucose->maintains blood glucose
Term
How does muscle uptake glucose with out insulin (as is the case with increase epinephrine concentration)?
Definition
-insulin independent mechanism!
-Exercise stimulates CaMK and AMPK
-CaMK and AMPK are active during high intensity exercise adn by pass insulin by inducing GLUT-4 uptake of glucose themselves.
-This form of glucose uptake is higher than insulin
-this is why exercise is the cure for diabetes.
Term
Cortisol's function
Definition
"the stress hormone"
-main purpose is mobilization of substrate
-Muscle: promotes the breakdown of protein to AA
-Adipose: stimulates lipolysis and release of FFA
-Liver: stimulates gluconeogenesis from AA and glycerol
-Blocks glucose uptake into the tissues and preserves glucose for the brain and RBCs.
Term
How is cortisol secretion controlled?
Definition
Cortisol is a steroid hormone that is controlled via a negative feedback system.
-it is synthesized in the adrenal cortex in response to stress
-The hypothalamus releases corticotropic-releaseing hormone (CRH) which stimulates the anterior pituitary gland to release Adrenocorticotropic hormone(ACTH) which stimulates the adrenal cortex to release cortisol
Term
What are the metabolic effects of Growth Hormone?
Definition
catabolic in metabolism.

-Liver: stims gluconeogenesis
-adipose: breaks down TG into FFA and glycerol
-tissues: blocks glucose entry causing increase FFA oxidation
Term
What are the metabolic pathologies associated with high levels of GH?
Definition
-Increased risk for cardiovascular disease
-->mobilization of FFA

-Increased incidence of sudden cardiac death
-->high FFA, low glucose causes cardiac arrhythemias

-Increased incidence of Type 2 diabetes
--> high glucose & inhibiiton of glucose uptake

-Abnormal lipid metabolism
->chronic FFA mobilization (tissues become desensitized to FFA)
Term
Hormones responsible for tissue growth and repair
Definition
Androgens
-testosterone
-dihydrotestosterone
-androstenedione

Growth Hormone
-Insulin-like growth factors (IGFs)
Term
Really cool facts about androgens
Definition
Androgens are steroid hormones
-cholesterol derivatives
-testosterone is most abundant in males

Produced in the testes
-secreted into the blood
-immediately bound to albumin or sex hormone-binding protein
-half-life: 30 min to several hours

Responsible for male features
Term
What are testosterone effects on growth?
Definition
Testosterone increases muscle prtein synthesis
-activation of satellite cells => hypertrophy
-enhances neuromuscular junction size and activity
-->all of which contribute to increased force production

testosterone is converted to estrogen
-contributes to long bone growth
-mineralization of bones (stronger bones)
Term
Describe Testosterone's response to exercise
Definition
A single bout of resistance exercise stimulates T production
-returns to baseline w/in hrs
-intensity-dependent (resistant)
-duration-dependent (aerobic)

Resistant training results in hight increaes in T product to single bout

Endurance trained athletes have lower testing T levels- 30-40%
Term
Some sweet GH facts
Definition
GH is a peptide hormone
-binds to cell surface and activates 2nd messenger
-secreted from the pituitary gland
-in response to GH releasing hormone (GHRH) from the hypothalamus

GH causes growth in almost all tissues

Increases linear growth pattern

Gh Stimulates the deposition of protein
-cartilage and bone
->increases osteogenic cell division
->deposition of new bone
-->epiphyseal growth (growth plates on long bones)
-->mineralization of bone

GH stimulates the liver (and other tissues) to produce insulin-like growth factors (IGF)
-most growth effects are carried out by IGFs
Term
Growth Hormone actions
Definition
GH secretion decreases about 50% after adolescence and drops to ~25% in the elderly

GH is released into the blood and taken up by tissues rapidly (20 min is half life)
-has to be made ahead of time

IGF is released slowly and half life is 20 hrs.
Term
How is GH secretion controlled?
Definition
Negative feedback system
-GH or IGF inhibits the release of more GHRH

Stimulation:
-protein deficiency
-hypoglycemia/lipidemia
-exercise (duration/intensity-dependent)
-excitement/trauma
-sleep: 1st 2hrs of REM
Term
What are the pathologies associated with GH?
Definition
1) Gigantism
-over production of GH (specifically IGF)
-Abnormally high linear growth

2)Dwarfism
-under production of GH
-stunted pre-pubescent growth (short long bones)
-2 types
--i) Anchondroplasia
---->bone growth defect prevents cartilage from being transform into bone
--ii) Short stature syndrom
----->pygmies of africa
----->GH levels normal but body can't synthesize IGFs

3)Acromegaly
-Overproduction of GH after adolescence
--stimulation of growth in facial bones, hands, and feet
--usually caused by pituitary gland tumor
Term
What are the primary renal functions?
Definition
-Regulation of body fluid volume and electrolytes (osmolarity)

-Regulation of acid-base balance (pH)

-Excretion of natural wastes and foreign chemicals

-Regulation of arterial pressure

-secretion of hormones (Epo)

-Gluconeogenesis
Term
What are the functions of the kidney?
Definition
kidneys filter ~ 180 L of plasma per day

Entire plasma volume is filtered 60x per day
-REtention of water and electrolytes
-excretion of waste.
-Tight control of plasma volume that helps maintain fluid balence.
Term
Describe the structure of the kidneys
Definition
-Renal artery supplies blood to the kidney.
-Blood enters the kidney medulla.
-Functional unit of hte kidney is hte Nephron.
-Nephron is the site of filtration, reabsorption, excretion
Term
Describe the nephron structure:
Definition
Nephron is composed of:
-Bowman's capsule which houses the glomerulus (site of filtration)
-Proximal tubule (colects the filtrate, primary site of reabsorption)
-Loop of Henle (site of reabsorption)
-Distal tubule
-Collecting duct (collects urine); drains to bladder
Term
Renal blood flow during exercise
Definition
RBF decreases w/ higher intensity exercise
-Rest: 1300 ml/min; ~20% of cardiac output
-Max Ex: ~750 mL/min; 3-5% of cardiac output
-->sympathetic stimulation- vasoconstriction of arterioles
Term
Describe the regulation of the flow of fluids
Definition
HYDROSTATIC PRESSURE
-The amount of pressure exerted by a fluid
-->plasma & interstitial fluid (extracellular) and intracellular
-Hydrostatic pressure is proportional to: volume of fluid, and area in which it's contained

OSMOLARITY
-The relationship b/t water and solutes in a solution
-concentration of solute per unit of fluid (moles of solute/liter of plasma)

OSMOTIC PRESSURE
-the pressure required to prevet the osmotic flow of fluid
Term
Antidiuretic Hormone (ADH)
Definition
-Peptide hormoen
-target tissue is kidney
-funciton is reabsorption of water, concentration of urine
-more specifically, ADH stimulates cells in teh collecting duct to become more permeable to water and water reabsorption occurs
-Feedback mechanism: decreased plasma osmolarity = decrease ADH release
Term
Describe IN DETAIL the renin angiotensin system
Definition
-Renin is secreted from the kidney in response to low blood pressure (decreased plasma volume)

-Renin release is proportional to exercise intensity

-Action of the renin_angiotensin system is to vasoconstrict arterioles and stimulate the release of Aldoesterone (a potent hormone that promotes the reabsorption of water and Na)
Term
Aldosterone
Definition
-Steroid hormone
-Produced by adrenal cortex in response to angiotensin II and decreased Na concentration
-stimulates water and na reabsorption in the distal tubule and water in the collecting duct.
-more specifically, aldosterone promotes gene expression of Na/K ion transporters in the distal tubuel
-as more Na is reabsorbed in the distal tubule more water can be reabsorbed from the collecting duct.
Term
Water and electrolyte balance is restored by the integration of _________ ________ and ______ ____
Definition
-Physiological reflexes (water loss & urinary excretion)

-Behavioral modifications (water intake & thirst)
Term
Adrenocorticotropic Hormone (ACTH)
Definition
Gland: Ant pit gland

Stimulus: TRH, stress, injur, disease

Target tissue: adrenal cortex

effect: stims secretion of corticosteroids
Term
Follicle Stimulating Hormone (FSH)
Definition
Gland: Ant Pit gland

Stim: GnRH (hypolthalamus)

Target tissue: Gonads (ovaries and testes)

Effect: Females-growth of ovarian follicles. Males- sperm production
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