How can we help?

You can also find more resources in our Help Center.

A&P Endo

STUDY
PLAY
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