A&P Endo

Created by sunshinemedic13 

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Describe paracrine action

A HORMONE DIFFUSES FROM ONE CELL THEN ACTS ON A NEARBY CELL
(cells are in the neighborhood)

Describe endocrine action

A HORMONE IS RELEASED INTO THE BLOOD THEN ACTS ON DISTANT CELLS

Describe autocrine action

A HORMONE ACTS ON THE SAME CELL THAT RELEASED IT
(self stimulators)

Exogenous hormone therapy (i.e. synthetic thyroid hormone) is utilized frequently in medical practice. List 2 patient factors that must be taken into account when prescribing exogenous hormone therapy

kidney function & liver function

What is the solubility characteristic of thyroid hormones and steroid hormones

lipid soluble

How are water-soluble hormones transported in the blood

free, unbound state

an example of the permissive effect of hormone interactions is epinephrine and thyroid hormones (T3&T4) describe this

epinephrine alone weakly stimulates lypolysis, but when a small quantity of thyroid hormone (T3 and T4) are present, epinephrine strongly stimulates lypolysis

what is an example (think pancreatis hormones) of antagonistic hormone interactions

glucagon and insulin

an example of synergistic hormone interactions is in the gonandotropins

estrogen + FSH stimulate the development of oocytes
(the effect of 2 hormones acting together is > the effect of each hormone alone)

How are lipid-soluble hormones transported in the blood

attached to a carrier protein

Briefly explain why receptors for lipid-soluble hormones are located inside target cells

THESE HORMONES EASILY DIFFUSE THROUGH THE LIPID BI-LAYER OF TARGET CELL MEMBRANES SO THEY ARE ABLE TO REACH INTRACELLULAR RECEPTORS

Briefly explain why receptors for water-soluble hormones are located within the plasma membrane of target cells

WATER-SOLUBLE HORMONES CANNOT EASILY DIFFUSE THROUGH THE PLASMA MEMBRANE OF TARGET CELLS. THE RECEPTOR HAS TO BE EXPOSED ON THE CELL SURFACE IN ORDER FOR THE HORMONE TO BIND TO IT

what 3 factors will determine the responsiveness of a target cell to a hormone

1. hormone concentration* can be affected in a big way
2. number of available receptors
3. the presence of other hormones

what are the 2 chemical classes of hormones

1. lipid soluble
2. water soluble

where are steroid hormones synthesized

adrenal glands, kidneys, gonads

what enhances the lipid solubility of tyrosine

iodination

What is the major determinant of the extent/amplitude of hormone action on target cells

NUMBER (OR CONCENTRATION) OF AVAILABLE RECEPTORS

The number of hormone receptors on target cells increases when the plasma concentration of a hormone decreases. This is known as

up-regulation

What is a first messenger

A WATER-SOLUBLE HORMONE BOUND TO A SURFACE RECEPTOR ON A TARGET CELL

What is/are the function(s) of second messengers

2nd messengers ARE CONSIDERED TO BE INTRACELLULAR MEDIATORS OF A HORMONE'S ACTION ON TARGET CELLS

describe lipid soluble hormone reserve (based on the hormone's mode of transportation)

As the hormone dissociates from its carrier protein, leaves the blood, then binds to a target cell receptor, other transport proteins release new free hormone into the blood to replace that which has bonded to target cell receptors

why can't you give insulin orally

Insulin is water-soluble: digestive enzymes destroy peptide bonds so insulin must be injected subcutaneously

Synthyroid (synthetic thyroid hormone) is lipid soluble, where is it absorbed

When taken orally, it is easily absorbed through the intestinal wall

describe down-regulation of hormone receptors

The number of receptors decreases when a hormone concentration in plasma increases
The target cell becomes less receptive to the hormone

Which hormone class utilizes second messengers

water-soluble

the most common second messenger

cyclic AMP

Phosphorylated enzymes regulate 4 target cell activities. List them

1.REGULATE INTRACELLULAR ENZYMES
2.REGULATE PROTEIN SYNTHESIS
3.REGULATE CELL SECRETIONS
4.REGULATE CELL MEMBRANE PERMEABILITY TO OTHER SUBSTANCES

IN NEGATIVE FEEDBACK: Activating hormones are secreted in response to a HIGH or LOW plasma concentration of a circulating hormone (the circulating hormone exerts effects at target cells).

LOW

IN NEGATIVE FEEDBACK: An increased plasma concentration of a circulating hormone exerts effects on hormone receptors located on the hypothalamus and pituitary gland. What effect does this have on synthesis and secretion of activating hormones

it decreases

IN NEGATIVE FEEDBACK: A gradually decreasing plasma concentration of circulating hormone with time (as it is utilized by target cells) eventually INCREASES or DECREASES secretion of activating hormones by the hypothalamus and pituitary gland

it increases

briefly describe positive feedback

THE RESPONSE TO A SECRETED HORMONE (INCREASED CONCENTRATION IN THE BLOOD) FEEDS BACK TO THE RELEASING ORGAN CAUSING CONTINUED OR INCREASED SECRETION OF THE HORMONE

List 2 other (besides +/- feedback)mechanisms for regulating/controlling hormone secretion

neural control
chemical control

Name the endocrine organ that is the major link between the nervous system and endocrine system

the Hypothalamus

The HYPOTHALAMUS regulates growth, development, metabolism, and overall body homeostasis by working with another endocrine organ. Name it:

THE PITUITARY

List the 5 releasing hormones from the Hypothalamus

GHRH: GROWTH HORMONE-RELEASING HORMONE
TRH: THYROTROPIN-RELEASING HORMONE
PRH: PROLACTIN-RELEASING HORMONE
CRH: CORTICOTROPIN-RELEASING HORMONE
GnRH: GONADOTROPIN-RELEASING HORMONE

These hypothalamic releasing hormones stimulate synthesis and release of hormones from which endocrine organ (be specific)

the Anterior Pituitary

List the 2 inhibiting hormones

GHIH: GROWTH HORMONE-INHIBITING HORMONE
PIH: PROLACTIN-INHIBITING HORMONE

What is another name for prolactin-inhibiting hormone?

DOPAMINE

2 hormones synthesized in the hypothalamus and stored for later release from the posterior pituitary gland:

ADH: ANTI-DIURETIC HORMONE
OXYTOCIN

Briefly describe how hypothalamic releasing / inhibiting hormones are transported to the anterior pituitary gland

hormones are released from vesicles at axon terminals near the base of the hypothalamus, they diffuse into the nearby PRIMARY CAPILLARY PLEXUS. blood flow carries the hormones to the SECONDARY CAPILLARY PLEXUS adjacent to the anterior pituitary gland. the hormones diffuse from the blood then attach to any available receptors on anterior pituitary target cells

what do SUPRAOPTIC NUCLEI in the hypothalamus synthesize

anti-diuretic hormone (ADH)

what do PARAVENTRICULAR NUCLEI in the hypothalamus synthesize

oxytocin

Briefly describe how ADH and Oxytocin hormones are transported from the hypothalamus to the posterior pituitary gland

they are packaged into secretory vesicles within the supraoptic & paraventricular nuclei. the secretory vesicles move down axons that extend from the hypothalamus into the Poterior Pituitary gland. The vesicles remain in the axon terminals within the posterior pituitary until needed

What is the stimulus for release of ADH and oxytocin

a neuroendocrine reflex

The pituitary gland is connected to the underside of the hypothalamus by what structure

the INFUNDIBULUM

What is another name for the anterior pituitary gland

ADENOHYPOPHYSIS

The 5 hormones synthesized and released by the anterior pituitary gland are known as ________ hormones

trophic

Briefly describe how trophic hormones enter the general blood circulation

TROPHIC HORMONES ARE RELEASED FROM ANTERIOR PITUITARY CELLS THEN THEY DIFFUSE INTO THE NEARBY SECONDARY CAPILLARY PLEXUS. THE BLOOD FLOW THROUGH THE CAPILLARY PLEXUS CARRIES THE HORMONES THROUGH THE ANTERIOR HYPOPHYSEAL VEINS INTO THE GENERAL CIRCULATION

List the 5 hormones synthesized by the anterior pituitary gland and the specific cell type involved

HUMAN GROWTH HORMONE (hGH): SOMATOTROPHS
PROLACTIN: LACTOTROPHS
ADRENOCORTICOTROPHIC HORMONE (ACTH): CORTICOTROPHS
THYROID-STIMULATING HORMONE: THYROTROPHS
FOLLICLE-STIMULATING HORMONE (FSH) AND LUTEINIZING HORMONE (LH): GONADOTROPHS

Most metabolic effects of human growth hormone (hGH) are mediated by what substance(s)

insulin-like growth factors (IGFs)

List locations where IGFs are produced

liver
bone
muscle
cartilage

What effect does hGH have on the plasma concentration of proteins

it increases

What effect does hGH have on the plasma concentration of glucose

it increases

What is the major regulator of hGH secretion

the plasma glucose concentration

When the plasma concentration of glucose is low, what effect does this have on secretion of growth-hormone inhibiting hormone (GHIH) and growth-hormone releasing hormone (GHRH)?

GHIH: decreases
GHRH: increases

the effects of GHIH and GHRH in response to low plasma glucose levels combine to INREASE or DECREASE hGH secretion

INCREASE

What effect(s) does stress and strenuous exercise have on hGH secretion

it increases

What effect do cortisol, insulin, glucagon, and estrogen secretion have on hGH secretion

it increases

what is the the most common etiology of pathologic hypersecretion of hGH

benign pituitary adenoma

in adults what disease is caused by hGH hypersecretion

Acromegaly

in children what disease is caused by hGH hypersecretion

Gigantism

Chronically-elevated plasma hGH exerts an adverse effect on pancreatic beta cells. What is this effect? What is the name for this effect

BETA CELLS EVENTUALLY CEASE RELEASE OF INSULIN. THIS IS KNOWN AS PITUITARY DIABETES.

hGH hyposecretion in childhood causes what disorder

Dwarfism

What is/are the primary function(s) of adrenocorticotrophic hormone (ACTH)

REGULATES SECRETION OF CORTISOL AND OTHER ADRENOCORTICOIDS FROM THE ADRENAL CORTEX

What is/are the primary function(s) of prolactin

initiates milk synthesis and secretion

Name the 2 hormones secreted by the hypothalamus that affect prolactin secretion:

PRH
PIH AKA Dopamine

Briefly describe how nursing affects dopamine and prolactin secretion

DOPAMINE SECRETION DECEASES
PROLACTIN SECRETION INCREASES

What is the most common cause of prolactin hypersecretion

A BENIGN PITUITARY ADENOMA (COMMONLY KNOWN AS A PROLACTINOMA)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion is stimulated by what hormone

decreased circulating testosterone and estrogen

what is another name for the posterior pituitary gland

neurohypophysis

The posterior pituitary gland is composed primarily of what type of tissue (be specific)?

axons and axon terminals (nerve tissues)

congenital dwarfism is due to

genetic IGF deficiency
normal levels of hGH

hypoglycemia and physical trauma can stimulate what

CRH and ACTH secretion

corticsol secreted from the adrenal cortex exertts _______ on CRH secretion form the hypothalamus and ACTH secretion from the anterior pituitarty

feedback inhibition

The quantity of ADH secreted by the posterior pituitary gland is in response to what two factors involving the blood circulation

blood osmotic pressure (plasma osmolarity)
blood volume

List the 3 tissues that have receptors for ADH and describe the action of ADH at each of these tissues

KIDNEYS: INCREASES WATER REABSORPTION BY RENAL TUBULES
SWEAT GLANDS: DECREASES SWEATING
VASCULAR SMOOTH MUSCLE: CAUSES VASOCONSTRICTION (ESPECIALLY DURING A SIGNIFICANT HEMORRHAGE

Release of atrial natriuretic peptide (ANP) has what effect on ADH secretion

it decreases

Diabetes insipidus is a disease process caused by insufficient ADH action on target tissues. List 2 ways this can occur

INSUFFICIENT RELEASE OF ADH FROM THE POSTERIOR PITUITARY
ADH RECEPTOR DEFECT AT THE KIDNEY TUBULES

What is the most common cause of neurogenic diabetes insipidus

head trauma

2 primary symptoms associated with diabetes insipidus

polyuria
polydipsia

2 primary functions of oxytocin

STIMULATES MILK EJECTION FROM THE BREASTS
STIMULATES UTERINE CONTRACTIONS DURING LABOR

Calcitonin (a hormone) is secreted by the thyroid gland. Name the cell type involved

parafollicular

A NON-PREGNANT, NON-LACTATING FEMALE complains of a milky breast discharge, what should you consider in the Dx of this patient

prolactinoma

describe the anatomy of thyroid follicles

MICROSCOPIC SPHERICAL SACS SURROUNDED BY FOLLICULAR CELLS

The lumen of thyroid follicles contains what substance

colloid

what is the primary protein contained in the colloid found in the lumen of thyroid follicles

thyroglobulin

what 2 hormones are synthesized by the thyroid follicles

T4- thyroxine
T3- triiodothyroxine

which hormone is secreted from the thyroid gland in the greatest quanity

T4

Thyroid hormone synthesis requires an adequate amount of a specific dietary substance in the blood. Name it:

Iodine

Name the amino acid within the protein thyroglobulin, found in colloid that fills the lumen of the thyroid, that is important in thyroid hormone synthesis:

Tyrosine

one iodine + tyrosine =

monoiodotyrosine (MIT)

two iodines + tyrosine =

diiodotyrosine (DIT)

thyroxine =

two DIT (no MIT)

triiodothyronine =

one MIT + one DIT

Once the 2 thyroid hormones are synthesized they remain attached to what substance within the colloid

thyroglobulin

Name the hormone that stimulates secretion of T3 and T4 from thyroid follicles:

THYROID-STIMULATING HORMONE (TSH)

in what state are T3 and T4 released into the blood

free (unbound)

More than 99% of the T3 and T4 released into the blood are immediately bound to a carrier/transport protein

Thyroxine-binding globulin

Name the 2 activating hormones that regulate secretion of T3 and T4 from the thyroid gland

THYROTROPIN-RELEASING HORMONE
THYROID-STIMULATING HORMONE

Increased concentration of circulating T3 and T4 affect secretion of the activating hormones. In what way(s)?

SECRETION OF BOTH TRH AND TSH DECREASES

A disease process involves the thyroid gland directly (a primary thyroid disorder) and causes insufficient T3 and T4 secretion into the blood circulation. How does this affect TRH and TSH secretion

SECRETION OF BOTH TRH AND TSH INCREASES

Colloid normally contains a thyroid hormone reserve. Approximately how many months worth

2-3

Several endogenous and exogenous factors affect (increase) TRH and TSH secretion. List 4 common ones

LOW BASAL METABOLIC RATE
HYPOGLYCEMIA
EXPOSURE TO A COLD ENVIRONMENT
PREGNANCY

TSH stimulates release of T3 and T4 from the thyroid gland. What other primary effect does it have on thyroid gland tissue

it stimulates follicular cell growth

How does thyroid hormone increase the basal metabolic rate (BMR)?

its activity at target cells increases ATP formation and utilization

Thyroid affects a specific cell membrane transport mechanism. Name it:

NA+ / K+ PUMPS

What effect(s) does thyroid hormone have on protein synthesis, cellular uptake of glucose, and lipolysis

all are stimulated by T3 and T4

What effect(s) does thyroid hormone have on BETA ADRENERGIC receptors on the heart and peripheral nerves

they are up-regulated

What effect(s) does thyroid hormone have on secretion of human growth hormone (GH)

it increases

List the 2 primary causes of hypothyroidism

A PRIMARY THYROID DISORDER - USUALLY DUE TO AN AUTOIMMUNE PROCESS
INADEQUATE SECRETION OF TSH FROM THE ANTERIOR PITUITARY GLAND

what is myxedema

SEVERE hypothyroidism in adults

Is hypothyroidism a common cause of obesity

no
ANY WEIGHT GAIN ASSOCIATED WITH HYPOTHYROIDISM IS MODEST (AVG 10-30 LBS)

Describe an endemic goiter

AN ENLARGEMENT OF THE THYROID GLAND THAT MAY BE SYMMETRIC OR ASYMMETRIC

List causes of an endemic goiter

MOST COMMON: DIETARY IODINE DEFICIENCY
INABILITY TO UTILIZE IODIDE TO SYNTHESIZE T3 AND T4

What is the pathophysiology of endemic goiter? (Be specific)

thyroid gland enlargement occurs as a result of TSH hypersecretion. TSH stimulates follicular growth

Briefly describe the pathophysiology of Graves' disease

an autoimmune disorder caused by production of an autoantibody (thyroid stimulating immunoglobulin) that mimics TSH at receptors. Pathologically increased amounts of T3 and T4 are synthesized and released into the blood circulation

Pathologically increased concentrations of circulating T4 and T3 affect the eyes in some patients with Graves' disease. How

RETRO-ORBITAL EDEMA CAUSES PROTRUSION OF THE EYES. THE EDEMA OCCURS IN THE EXTRA-OCULAR MUSCLES
exophthalmos

Many symptoms and signs of Graves' disease are due to thyroid hormone effects on tissues such as the heart and nervous system. What is happening to target tissue receptors for T3 and T4 that cause these signs and symptoms

up-regulation of BETA-ADRENERGIC receptors

Normal regulation of circulating calcium is important for the proper function of some physiologic processes. List the 3 mentioned in lecture

NERVE IMPULSE INITIATION, PROPAGATION, AND SYNAPTIC VESICLE RELEASE
MUSCLE ACTION POTENTIALS
BLOOD COAGULATION

List the 3 factors that affect bone breakdown and bone formation

RATIO OF OSTEOBLAST TO OSTEOCLAST ACTIVITY
INTESTINAL ABSORPTION OF CALCIUM AND PHOSPHATE
URINARY EXCRETION OF CALCIUM AND PHOSPHATE

List the 3 major hormones involved in calcium homeostasis and the role of each

PARATHYROID HORMONE (PTH): INCREASES BLOOD CALCIUM AND DECREASES PHOSPHATE
CALCITONIN: DECREASES BLOOD CALCIUM AND PHOSPHATE
CALCITRIOL: INCREASES BLOOD CALCIUM AND PHOSPHATE CONCENTRATION

Briefly describe the location of the parathyroid glands

THEY ARE IMBEDDED IN THE POSTERIOR ASPECT OF THE THYROID GLAND - 2 IN EACH LOBE (usually)

What cell type within the parathyroid glands is responsible for synthesis of parathyroid hormone (PTH)?

principle (chief) cells

Where is calcitonin synthesized

IN PARAFOLLICULAR "C" CELLS IN THE THYROID GLAND

List the 3 mechanisms by which PTH increases the plasma calcium concentration

INCREASES OSTEOCLAST ACTIVITY RELEASING CALCIUM INTO THE BLOOD
INCREASES RENAL TUBULAR REABSORPTION OF CALCIUM
STIMULATES RENAL SYNTHESIS OF CALCITRIOL (VITAMIN D)

What is the primary stimulus for secretion of PTH

DECREASED PLASMA CALCIUM CONCENTRATION

List 2 mechanisms by which calcitonin decreases the plasma calcium concentration

INHIBITS FORMATION AND ACTIVITY OF OSTEOCLASTS
DECREASES RENAL TUBULAR REABSORPTION OF CALCIUM

Is calcitonin an important hormone in the adult? Why or why not?

NO
AFTER SKELETAL MATURITY THERE IS MUCH LESS BONE FORMATION AND REMODELING

What are 2 other names for 1,25-dihydroxycholecalciferol

CALCITRIOL
VITAMIN D

List the 3 organs responsible for synthesis of 1,25-dihydroxycholecalciferol (Calcitriol, Vitamin D)

skin
liver
kidneys

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