Endocrine Answer Key

8/15/2019 Endocrine Answer Key

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I. General Characteristics of the Endocrine System

A. The endocrine glands secrete hormones.

B. Hormones diffuse from interstitial fluids into the blood stream and eventually act on

target cells.

C. Paracrine secretions are secretions that do not travel in the blood stream to their

targets.

D. Autocrine secretions are secretions that affect the secreting cell itself.

E. Exocrine glands secrete substances into ducts.

F. Endocrine glands and their hormones control metabolic rocesses.

!. Endocrine hormones also lay vital roles in reroduction" develoment" and gro#th.

H. The larger endocrine glands are the ituitary" thyroid" arathyroids" adrenals" and

ancreas.

II. Hormone Action

A. $ntroduction

%. Hormones only affect their target cells.

&. Target cells have recetors for articular hormones.

B. Chemistry of Hormones

%. $ntroductiona. 'teroid hormones are synthesi(ed from cholesterol.

b. )onsteroid hormones are synthesi(ed from amino acids.

&. 'teroid Hormones

a. 'teroids are liids that include comlex rings of carbon and hydrogen atoms.

b. Examles of steroid hormones are testosterone" estrogen" aldosterone" and

cortisol.

*. )onsteroid Hormones

a. Examles of hormones called amines are noreinehrine and einehrine.

b. Protein hormones are comosed of long chains of amino acids.

c. Examles of rotein hormones are those secreted by the anterior ituitary and

arathyroid glands.

d. Hormones called glycoroteins are roduced by the anterior ituitary.


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e. Petide hormones are short chains of amino acids.

f. Petide hormones come from the osterior ituitary and hyothalamus.

g. Prostaglandins are aracrine substances and are roduced in a #ide variety of

cells.

C. Actions of Hormones

%. $ntroduction

a. Hormones exert their effects by altering metabolic rocesses.

b. Hormones may reach all cells but only affect those that have aroriate recetors.

c. The more recetors the hormone binds on its target cell" the greater the resonse.

&. 'teroid Hormones

a. 'teroid hormones are insoluble in #ater but are soluble in liids.

b. 'teroid hormones can diffuse into cells relatively easily.

c. +nce steroid hormones are inside a cell" they combine #ith secific rotein recetors

located usually in the nucleus.

d. The binding of a steroid hormone to its recetor usually activates or inhibits a gene.

e. Activated genes code for secific roteins.

f. The ne# roteins may be en(ymes" transort roteins" or hormone recetors and they

bring about cellular changes.

*. )onsteroid Hormones

a. A nonsteroid hormone usually binds #ith recetors located on the cell membrane.

b. ,hen a nonsteroid hormone binds to a membrane recetor" this causes the recetor-s

activity site to interact #ith other membrane roteins.

c. ecetor binding may alter the function of en(ymes or membrane transort

mechanisms" changing the concentrations of still other cellular comonents.

d. A first messenger is the hormone.

e. 'econd messengers are the chemicals in the cell that induce the changes that are

recogni(ed as resonses to the hormone.

f. /any hormones use cyclic A/P as a second messenger.

g. ! roteins are activated by the binding of a hormone to a membrane recetor.


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h. Adenylate cyclase is activated by ! roteins.

i. Adenylate cyclase functions to form cyclic A/P from ATP.

0. Cyclic A/P activates another set of en(ymes called rotein 1inases.

1. Protein 1inases function to transfer hoshate grous from ATP to roteins substrate

molecules.

l. Phoshorylated substrates may be converted from inactive to active forms.

m. Activated roteins then alter various cellular rocesses to bring about the effect of

that articular hormone.

n. Hormones #hose actions deend uon cyclic A/P include releasing2hormones from

the hyothalamus" T'H" ACTH" F'H" 3H" ADH" PTH" noreinehrine" einehrine"

glucagon" and calcitonin.

o. An examle of another second messenger is DA!.

. $n another mechanism" a hormone binding to its recetor increases calcium" ion

concentration #ithin the target cell.

4. Calcium ions bind to the rotein calmodulin to activate it.

r. Activated calmodulin functions to interact #ith en(ymes" altering their activities.

s. Cells are highly sensitive to changes in concentration of nonsteroid hormones because

resonses to them is greatly amlified through second messengers.

D. Prostaglandins

%. Prostaglandins are aracrine substances that act locally.

&. 'ome rostaglandins regulate cellular resonses to hormones.

*. The variety of effects rostaglandins can roduce include relaxation of smooth muscle

in air#ay and blood vessels" contraction of smooth muscle in the uterus" stimulation of

secretion of various hormones" and romotion of inflammation.

III. Control of Hormonal Secretions

A. $ntroduction

%. Hormones are continually excreted in urine and bro1en do#n by en(ymes in the liver.

&. $ncreasing or decreasing blood levels of hormones re4uires increased of decreased

secretion.


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B. Control 'ources

%. The hyothalamus controls the anterior ituitary gland-s release of troic hormones.

&. Troic hormones are those that stimulate other endocrine gland sto release hormones.

*. An examle of an endocrine organ directly stimulated by the nervous system is the

adrenal medulla.

5. 'ome endocrine glands resond to changes in the comosition of the internal

environment.

6. As a result of negative feedbac1 mechanisms" hormone levels remain relatively stable.

IV. Pituitary Gland

A. $ntroduction

%. The ituitary gland is located at the base of the brain.

&. The infundibulum is a stal1 that attaches the ituitary gland to the hyothalamus.

*. The t#o ortions of the ituitary are anterior and osterior.

5. The anterior lobe secretes the follo#ing hormones7 !H" T'H" ACTH" F'H" 3H" and

P3.

6. The osterior ituitary secretes the follo#ing hormones7 +T and ADH

8. The hyothalamus controls most of the ituitary gland-s activities.

9. The osterior ituitary receives imulses from the hyothalamus.

:. eleasing hormones from the hyothalamus control the anterior ituitary.

;. The hyohyseal ortal veins are vessels that ass do#n#ard along the ituitary stal1

from the hyothalamus and give rise to a caillary be in the anterior lobe of the ituitary.

B. Anterior Pituitary Hormones

%. 'omatotroes secrete !H.

&. /ammotroes secrete P3.

*. Thyrotroes secrete T'H.

5. Corticotroes secrete ACTH.

6. !onadotroes secrete F'H and 3H.

8. Actions of gro#th hormone are stimulation of cells to enlarge and more raidly divide"

enhance movement of amino acids through the cell membranes" and increases the rate of


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rotein synthesis. !H also decreases the rate as #hich cells utili(e carbohydrates and

increases the rate at #hich cells use fats.

9. The secretion of !H is controlled by somatostatin and !HH.

:. Actions of rolactin are to sustain mild roduction after birth and to amlify effect of

3H in males.

;. The secretion of P3 is controlled by P$H and PF.

%


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V. Thyroid Gland

A. $ntroduction

%. The thyroid gland consists of t#o lobes.

&. The thyroid gland is located 0ust belo# the larynx on either side and anterior to the

trachea.

B. 'tructure of the !land

%. Follicles are secretory arts of the thyroid gland.

&. Colloid is a viscous fluid that fills follicles and contains thyroglobulin.

*. Thyroglobulin is a glycorotein.

5. Extrafollicular cells are located outside of follicles.

6. The follicular cells roduce hormones.

C. Thyroid Hormones

%. The three hormones roduced by the thyroid gland are T5" T*" and calcitonin.

&. The actions of thyroxine and triiodothyronine are to regulate metabolism of

carbohydrates" liids" and roteins.

*. The secretion of T* and T5 are controlled by T'H.

5. Follicular cells re4uire iodine to roduce T* and T5.

6. The actions of calcitonin are to lo#er blood calcium levels.

8. The secretion of calcitonin is controlled by blood calcium levels. $t is released in

resonse to high blood calcium levels.

VII. Parathyroid Glands

A. $ntroduction

%. Parathyroid glands are located embedded in the thyroid gland.

&. =sually a erson has four arathyroid glands.

B. 'tructure of the !lands

%. Each arathyroid gland is covered by a thin casule.

&. The body of a arathyroid gland consists of many tightly ac1ed secretory cells.

C. Parathyroid Hormone


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%. The actions of PTH are to raise blood calcium levels.

&. The secretion of PTH is controlled by blood calcium levels. $t is released in resonse

to lo# blood calcium levels.

VIII. Adrenal Glands

A. 'tructure of the !lands

%. The adrenal glands are shaed li1e yramids.

&. The t#o arts of an adrenal gland are the cortex and medulla.

*. The adrenal medulla consists of irregularly shaed cells groued around blood vessels.

5. The adrenal cortex is comosed of closely ac1ed masses of eithelial layers.

6. The three layers of the adrenal cortex are the outer (ona glomerulosa" the middle (ona

fasciculata" and the inner (ona reticulairs.

B. Hormones of the Adrenal /edulla

%. The t#o hormones released by the adrenal medulla are einehrine and

noreinehrine.

&. The actions of einehrine and noreinehrine are increased heart rate" increased force

of cardiac muscle contraction" elevated blood ressure" increased breathing rate and

decreased activity of the digestive system

*. The secretion of einehrine and noreinehrine are controlled by the symathetic

nervous system.

C. Hormones of the Adrenal Cortex

%. $ntroduction

a. The adrenal cortex roduces more than *< different steroids.

b. The most imortant adrenal cortical hormones are aldosterone" cortisol" and

certain sex hormones.

&. Aldosterone


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a. Aldosterone is secreted by the (ona glomerulosa and is called a

mineralocorticoid because it hels regulate the concentration of mineral electrolytes.

b. The actions of aldosterone are regulation of concentration of extracellular

electrolytes by conserving sodium ions and excreting otassium ions.

c. The secretion of aldosterone is controlled by electrolyte concentrations in body

fluids and the renin2angiotensin mechanism

*. Cortisol

a. Cortisol is secreted by the (ona fascilulata and is called a glucocorticoid because it

affects glucose metabolism

b. The actions of cortisol are to decrease rotein synthesis" increase fatty acid release"

and simulate glucose synthesis from noncarbohydrates.

c. The secretion of cortisol is controlled by CH.

5. 'ex Hormones

a. The sex hormones are secreted by the (ona reticularis.

b. The actions of the sex hormones are to sulement sex hormone from the gonads.

c. Examles of sex hormones are androgens such as testosterone.

IX. Pancreas

A. 'tructure of the !land

%. The ancreas is located osterior to the stomach.

&. The endocrine ortion of the ancreas consists of islets of 3angerhans #hich are also

called ancreatic islets.

*. Three cell tyes of the ancreatic islets are alha" beta" and delta.

5. Alha cells secrete glucagon.

6. Beta cells secrete insulin.

8. Delta cells secrete somatostatin.

B. Hormones of the Pancreatic $slets


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%. The actions of glucagon are to stimulate the liver to brea1 do#n glycogen and to

convert noncarbohydrates into glucose. $t also simulated the brea1do#n of fats.

&. The secretion of glucagon is controlled by blood glucose concentrations.

*. The actions of insulin are to romote the formation of glycogen from glucose" to

inhibit conversion of noncarbohydrates into glucose" and to enhance movement of

glucose through adiose and muscle cell membranes. $t also decreases blood glucose

concentrations" romotes transort of amine acids into cells" and enhances synthesis of

roteins and fats.

5. The secretion of insulin is controlled by blood glucose concentrations.

6. The function of somatostatin is to hel regulate carbohydrates.

X. Other Endocrine Glands

A. Pineal !land

%. The ineal gland is located near the roof of the third ventricle.

&. The ineal gland roduces the hormone melatonin.

*. The functions of melatonin are to hel regulate circadian rhythms and

to inhibit secretion of gonadotroins.

B. Thymus gland

%. The thymus gland is located bet#een the lungs.

&. The thymus gland secretes a grou of hormones called thymosins.

*. The function of thymosin is to romote the maturation of T

lymhocytes.

C. eroductive +rgans

%. eroductive organs that secrete hormones are ovaries and testes.

&. Examles of hormones roduced by reroductive organs are estrogen"

rogesterone" and testosterone.

D. +ther Hormone2Producing +rgans

%. The hormone roduced by the heart is A)P.

&. The hormone roduced by the 1idneys is erythrooietin.


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XI. Stress and Its Effects

A. $ntroduction

%. A stressor is a factor caable of roducing stress.

&. 'tress is a rotective resonse roduced by the body in resonse to stress factors.

B. Tyes of 'tress

%. Examles of hysical stress include extreme cold or heat" decreases oxygen

concentrations" infection" in0uries" heavy exercise and loud sounds.

&. Examles of sychological stress are imagined dangers" ersonal losses" unleasant

social interaction or any factor that threatens a erson.

C. esonses to 'tress

%. The general stress syndrome is a grou of symtoms roduced by the hyothalamus in

resonse to stress.

&. /a0or events of the general stress syndrome are increased blood glucose levels"

increased heart rate and breathing rate" dilation of air#ays" and shunting of blood into

muscles.

XII. LifeS!an Chan"es

A. !eneral changes in the glands of the endocrine system are a decrease in si(e and

increase in the roortion of each gland that is fibrous in nature.

B. Treatments for endocrine disorders include sulements of hormones or removing

art of an overactive gland or using drugs to bloc1 the action of an overabundant

hormone.

C. 3evels of ADH increase #ith age and as a result" the 1idneys reabsorb more #ater.

D. The decrease of calcitonin levels #ith age increases the ris1 of osteoorosis.

E. The most obvious changes in endocrine function involve blood glucose regulation.

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Endocrine Answer Key