Download Chapter 26 - Scranton Prep Biology

26
ChanicalRegulation
As you read this, your blood is carrying dozens of different hormones from endocrine
glands to target cellsall over your body. Thesehormones are chemicalsignalsthat regulate
the activitiesof every cell. Hormones coordinatethe activitiesof body organs,maintaining homeostasis.Their effectson their targetsrange from tiny adjustmentsin chemistry to
control of large-scalebody processes,such as growth and reproduction. Hormones are produced in minuscule amounts; cells are capable of responding to very subtle signals.
Hormones carry specificmessages,and eachcell is equipped to respond only to certain
ones.Different target cells may even respond differently to the samehormone. This subtle and intricate hormone communication and control systemis the subjectof Chapter 26.
Organizing Your Kn owl edge
This module describesthe roles of chemical signals in the function of the endocrine and
nervous systems.Color and label the diagrams below, comparing the activities of endocrine cells,neurosecretorycells,and nerve cells.Label the following: neurosecretory
cell, hormone molecules,nerve signals,endocrinecell, neurotransmittermolecules,se'
cretory vesicles,target cell, blood vessel,and nerve cell. Note that the diagramsare not
in the sameorder as those in the text. Choosea color for each of the cells. Make hormone
moleculesfrom the endocrinecell green dots, hormone moleculesfrom the neurosecretorv cell blue dots, and neurotransmitter moleculesred dots.
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ChemicalRegulation
of CellSignaling
Web/CDActivity26A Overview
HormoneAction
Web/CDActivity26B Nonsteroid
Web/CDActivity26C SteroidHormoneAction
just about everything you need to know about the mechanismsby which hormones affect
their target cells is summarizedin the two figures in Module 26.2.Toreview them, label the
diagrams below. Choosefrom: DNA, steroid hormone, enzyme/ receptor protein, plasma
membrane, target cell, new protein, signal transduction pathway, epinephrine, cellular
response/nucleus,hormone-receptorcomplex,and relay molecules.
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28.2
Chapter26
Web/CDActivity26D HumanEndocrine
Glandsand Hormones
This module is an overview of the glands and hormonesdiscussedin this chapter.You may
want to refer back to the diagram and table as referencesasyou read about glands and hormones in the modules that follow. Label the human endocrine glands on the diagram
below, and color eachone a different color. Choosefrom thymus, testis, pineal gland, pituitary gland, adrenal glands, parathyroid glands, pancreas,thyroid gland, hypothalamus, and ovary. Consulting Table 26.3in the text, list under the name of eachgland one
of the hormones it produces.
ChemicalRegulation
28,3
The table in Module 26.3is a useful summary of glands, hormones,and hormone actions.
Use it to completethe following chart by filling in the blanks. Note that the order of the
glands here is different from the table in the text. (You may want to skip this for now and
come back to it as a review after you have studied the glands and hormones in the following modulesin more detail.)
GIand
1.
HormoneG)
2 .& 3 .
Calcitonin
Ovaries
5.
Progesterone
8.
9. & 10.
Action
Control metabolic processes
4.
6.
7.
Trigger "fight or flight" response
Glucocorticoids
t2.
13.
Regulatemineral gain and lossby kidneys
Glucagon
14.
15.
T6.
17.
18.
Raises blood calcium level
t9
Melatonin
20.
27.
22.
Stimulatesgrowth
Thyroid-stimulating hormone
23.
Prolactin
24.
25.
Stimulates adrenal cortex
Luteinizing hormone
26.
27.
Stimulatesegg and sperm production
Oxytocin
28.
29.
Promoteswater retention bv kidnevs
Thymus
30.
31.
JZ.
Androgens
33.
34.
Hormones that regulate anterior
pituitary; hormones releasedby
posterior pituitary
Affect pituitary
11.
Pancreas
Posterior pituitary
284
Chapter26
The hypothalamus and pituitary glands are closely related and tie the nervous and endocrine systemstogether. But the anterior and posterior lobes of the pituitary do different
jobs and are controlled in different ways. Statewhether eachof the following relatesto
the hypothalamus (H), anterior lobe of the pituitary (A), or posterior lobe of the pituitary
(P).
_
_
_
_
_
1 . Storesand secreteshormones actually made in the hypothalamus
2. Secretesreleasingand inhibiting hormones that stimulate the anterior pituitary
3. Composed of nonnervous, glandular tissue
4. Part of the brain
5. \A/herethe hormones oxytocin and ADH are releasedinto the blood
6. Respondsto releasingand inhibiting hormones from the hypothalamus
7. Secretesgrowth hormone, ACTH, and thyroid-stimulating hormone
8. Is the terminus of neurosecretorycells from the hypothalamus
9 . Most hormones that it secretesinfluence other endocrine glands
10.Exertsmaster control over the endocrine system
1 1 .Consistsof nervous tissue and is actually an extensionof the hypothalamus
12. Negative feedbackusually acts on this part of the system
13.Blood vesselscarry releasinghormones from here to the anterior pituitary
14. Along with the brain, it secretesthe body's natural painkillers
Most people know at least a little about the thyroid gland. Once you understand that thyroid hormonesstimulate metabolism,it is easyto rememberthe symptoms of over- and undersecretionand the effectsof thyroid medication. Review the thyroid gland by matching
eachphrase on the right with a substanceon the left.
A.Iodine
B'Ta
C. TSH
D. T,
E. TRH
1. Secretedby hypothalamus; stimulates anterior pituitary
2. Secretedby anterior pituitary; stimulates thyroid
3. Hormone secretedby thyroid
4. Another hormone secretedby thyroid
5. Needed for the manufacture of thyroid hormones
6. T, and Tn signal the hypothalamus to stop making this
7. Goiter occursif there is not enough of this in the diet
8. Also called thyroxine
Chemical Regulation
285
Two opposing,or antagonistic,hormonescontrol the balanceof calcium in the blood. To review calcium homeostasis,study Figure 26.7in the text. Use it to help you choosethe correct italicized words to complete the following paragraph.
Calcium is important for nerve impulse transmission,muscle contraction,transport of moleculesthrough cell membranes,and (1) digestion,proteinsynthesis,bloodclotting. Blood calcium concentrationis held in a narrow range by the thyroid and parathyroid glands. If blood calcium drops, the (2) thyroidgland,parathyroidglandsincrease(s)
decreased
secretionof (3) parathyroidhormone,calcitonin.This causes(4) increased,
reabsorption of calcium as the kidneys form urine, (5) increased,
decreased
absorption of calcium
from food, and (6) release
of calciumftom, depositionof calciuminbone.If blood calcium
concentrationclimbs too high, (7) parathyroidhormone,calcitoninis secretedby the
(8) thyroidgland,parathyroidglands.This causes(9) increased,
decreased
reabsorption of
calcium in the kidneys, and (1.0)release
of cnlciumfrom,depositionof calciuminbone.
To understand how the pancreascontrolsblood sugar,you need to rememberonly two
things: (1) the pancreasmakes two hormones, insulin and glucagon, and (2) diabetics
have high blood sugar, so many of them take insulin. Given these two facts, you can figure everything elseout: If diabeticshave to take insulin, insulin must make blood sugar
go down. It must make cells take sugar out of the blood and use it or store it. That means
glucagon must make blood sugar go up, by causing cells to get it out of storageand put it
into the blood. Finally, an increasein blood sugar must trigger insulin secretion(to make
sugar go down), so a drop in blood sugar must trigger glucagon secretion(to make blood
sugargo up).
To review control of blood sugar level, choose either the word increase(s)
or
decrease(s)
to complete eachof the following statements.
1. Eatins a meal rich in carbohvdratescausesblood slucoseto
the pancreassecretesmore insulin.
2. \Atrhen
blood glucose-
their uptake and use of glucose.
3. Insulin causesbody cells to
4. Insulin also causesglycogen formation by the liver to
5. Insulin therefore causesblood glucoseto
6. Betweenmeals,blood glucoselevels tend
the pancreassecretesmore glucagon.
7. \zVhenblood glucose8. Glucasoncausesblood elucoseto
9. Glucagon
breakdown of glycogen in the liver and release of glucose to the blood.
10. Glucagon also triggers liver cells to
conversion of fats to glucose.
11. As blood glucoserises toward the set point, secretionof glucagon
12. In type I diabetes,blood sugar
13. In type II diabetes,there is a
becausethe body is unable to produce insulin.
in cells' ability to respond to insulin.
14. Hypoglycemia results from an excess of insulin, which causes a sudden
in blood glucose.
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Chapter26
The adrenal gland is similar to the pituitary in that it is two glands in one. The parts have
different jobs and send out different hormones.One of its parts (the medulla) is stimulated by nerve impulses to secreteits hormones,while the other part (the cortex) is stimulated by hormonal signals.The hormonesfrom the adrenal medulla and cortex help the
body deal with stress.After reading the modules and studying Figure 26.10in the text,
try to match eachof the phraseson the right with adrenal stresshormones,E, M, or G.
E. Epinephrine and
norepinephrine
M. Mineralocorticoids
G. Glucocorticoids
1. Increasebreathingrate
2. Respondto short-term stress
3. Secretedby the adrenalcortex
4. Also secretedby the adrenalcortex
5. Increaseblood volume and p'ressurein responseto long-term stress
6. Triggered by nerve impulses from the hypothalamus
7. Secretedby the adrenal medulla
8. Causeproteins and fats to be broken down to make glucose
9. Triggered by ACTH from the pituitary
10.Also triggered by ACTH from the pituitary
11.Suppressthe inflammatory responseand immune system
12.Causeretention of sodium and water by kidneys
13.Dilate and/ or constrictblood vessels,redirectingblood flow
14.Increasemetabolicrate
15.Often prescribed to relieve pain from athletic injuries
_
Web/CDActivity26D HumanEndocrine
GlandsandHormones
Sexhormones are discussedin more detail in Chapter 27. After reading Module 26.72,try
sketchingon a separatesheetof paper a conceptmap for sexhormones.Referto Chapter
3, Exercise10,for a discussionof constructing a conceptmap. Include the following in your
conceptmap: testosterone,gonads,estrogens,hypothalamus, FSH and LH, progestins,
testes,releasingfactor,anterior pituitary, ovaries,sexhormones,and steroids.
On a separatesheetof paper, briefly describehow the items in eachof the following groups
are related to one another.They may affect one another,opposeone another,or have something in common.
L. luteinizing hormone
2. oxytocin
a
glucocorticoids
4. glucocorticoids
6. thyroxine
calcitonin
7. glucagon
insulin
8. glucocorticoids
1 1 .oxytocin
follicle-stimulating hormone
LH
epinephrine
ACTH
5. antidiuretic hormone
10. calcitonin
androgens
antidiuretic hormone
glucagon
9 . ACTH
estrogens
mineralocorticoids
T3
epinephrine
growth hormone
parathyroid hormone
prolactin
parathyroid hormone
mineralocorticoids
FSH
TSH
norepinephrine
prolactin
calcitonin
ChemicalRegulation
d. It stops hormone action when it is no longer
needed.
e. It carriesa hormone while it is in the blood.
Knowledge
TbstingYour
Multiple
Choice
n
L. Another system that works closely with the endocrine system to control body processesis the
a. circulatory system.
b. immune system.
c. digestive system.
d. nervoussystem.
e. muscular system.
2. Every time you eat a cookie or candy bar, your
blood sugar increases.This triggers an increase
in the hormone
a. thyroxine.
b. epinephrine.
c. adrenocorticotropin (ACTH).
d. glucagon.
e. insulin.
3. Every hormone
a. is a protein.
b. is produced in responseto stress.
c. is under the control of the pituitary gland.
d. entersa cell and interactswith DNA.
e. acts as a signal between cells.
4. Researchershave found increasedlevels of
in the blood of stuhormones from the dents preparing for final exams.Thesehormones are produced in responseto stress.
a. thyroid gland
b. pineal gland
c. posteriorpituitary
d. adrenal glands
e. parathyroid glands
5. \Atrhichof the following hormones have antagonistic (opposing) effects?
a. thyroxine and calcitonin
b. insulin and glucagon
c. growth hormone and epinephrine
d. ACTH and glucocorticoids
e. epinephrine and norepinephrine
5. \A/hatis the role of a receptor in hormone action?
a. It signals a cell to secretea hormone.
b. It informs a gland as to whether its hormones are having an effect.
c. It enablesa target cell to respond to a
hormone.
247
When a boy goesthrough puberty, the steroid
"puts hair on his chest"
hormone testosterone
by
a. interacting with DNA in the nuclei of celis.
b. causingcellsto changeshape.
c. altering the permeability of plasma membranes.
d. triggering nerve impulses in cells.
e. turning enzymeson.
8. A hormone from the parathyroid glands works
to
in opposition to a hormone from the resulate
a. posterior pituitary . . . metabolic rate
b. thyroid gland . . . blood calcium
c. pancreas.. . water reabsorption
d. adrenalmedulla . . . blood calcium
e. thyroid gland. . . blood glucose
9 . Someglands produce hormones that stimulate
other endocrine glands. \zVhichof the following
hormones specifically acts to trigger secretion
of hormonesby another endocrine gland?
a. thyroxine
b. progesterone
c. adrenocorticotropin (ACTH)
d. antidiuretic hormone (ADH)
e. melatonin
10. How is the level of thyroxine in the blood
regulated?
a. Thyroxine stimulates the pituitary to secrete
thyroid-stimulating hormone (TSH).
b. TSH inhibits secretionof thyroxine from the
thyroid gland.
c. TSH-releasinghormone (TRH) inhibits secretion of thyroxine by the thyroid gland.
d. Thyroxine stimulates the hypothalamus to
secreteTRH.
e. Thyroxine and TSH inhibit secretionof
TRH.
11.. Steroid hormones are produced only by the
a. adrenalmedulla and pancreas.
b. thyroid gland and pancreas.
c. anterior and posterior pituitary.
d. thyroid gland and sex organs.
e. sexorgansand adrenalcortex.
2AA
Chapter26
12. It usually takes much longer for sex hormones
and other steroids to produce their effectsthan
it takes for most nonsteroid hormones.Why?
a. Steroidsare bigger, slower molecules.
b. Steroidsusually must be carried longer distancesby the blood.
c. Steroidscausetarget cells to make new proteins, which takes time.
d. Steroidsmust relay their messagevia a
receptor.
e. It takes longer for endocrine cells to make
and secretesteroids.
1.3. The pituitary is actually two glands. The anterior lobe of the pituitary secretesits hormones
when stimulated by
and the posterior
lobe of the pituitary secretesits hormones
when stimulatedby
a. hormones from the adrenal cortex . . . hormones from the thyroid
b. hormones from the hypothalamus . . . nerve
impulses from the hypothalamus
hormones
from the hypothalamus . . . horc.
mones from the thyroid
d. nerve impulses from the hypothalamus . . .
hormones from the hypothalamus
e. hormones from the pineal gland . . . hormones from the pancreas
14. Injectionsof a hormone are sometimesgiven to
strengthencontractionsof the uterus during
childbirth. What hormone might this be?
a. adrenocorticotropin (ACTH)
b. thyroxine
c. oxytocin
d. insulin
e. follicle-stimulating hormone (FSH)
15. \Atrhichof the following hormones has the
broadest range of targets?
a. ADH
b. prolactin
c. TSH
d. epinephrine
e. calcitonin
Essay
1. The pituitary is often called the master gland.
Lr what way is this true? In what way is it misleading?
2. Compare how the adrenal cortex and adrenal
medulla deal with stress.
3. How are hormones and neurotransmitters
alike? How are they different?
4. Briefly describean example of a hormonal diseaseor abnormality in which
a. too much hormone is secreted.
b. not enough hormone is secreted.
c. hormone is secretedin a normal amount,
but cells fail to respond.
5. Why are glucocorticoidsuseful in treating injuries? \A/hyis prolonged use of glucocorticoids
risky?
6. Describetwo different situations in which a
pair of hormones have opposite (antagonistic)
effectson the body.
epp Ui"S Your Knowleilge
Multiple
Choice
1. Jetlag occurswhen a personmovesrapidly
from one time zone to another, causing conflict
between the body's biological rhythm and the
new cycle of light and dark. Somescientists
suspectthat jet lag may result from disruption
of a daily hormone cycle. \Atrhichof the following hormones do you think is the most likely
suspect?
a. epinephrine
b. insulin
c. melatonin
d. estrogen
e. prolactin
2. Which of the following hormones triggers secretion of ihe other two?
a. thyroxine
b. thyroid-stimulating hormone (TSH)
c. TSH-releasinghormone (TRH)
d. Any of the above can trigger secretionof the
others.
e. None of the above can trigger secretionof
the others.
3. A tumor in an endocrine gland caused|ennifer
to have weakenedbones and unusually high
levels of blood calcium. Which of the following
was affected?
a. anterior pituitary
b. pancreas
c. adrenal glands
d. parathyroid glands
e. thymus
ChemicalRegulation
4. Which of the following exertscontrol over all
the others?
a. adrenal cortex
b. hypothalamus
c. thyroid gland
d. anterior pituitary
e. testes
5. Becauseonly the
gland usesio-
dine to make its hormones, radioactive iodine
is sometimes used as a treatment for tumors of
this gland.
a. pituitary
b. pancreatic
c. thyroid
d. adrenal
e. testicular
6 . Diabetes insipidus is an inherited endocrine
malfunction (unrelated to diabetes mellitus) in
which the kidneys fail to reabsorb normal
amounts of water. Victims of this disease produce gallons of urine each day, and their kidneys soon wear out. Treatment of this disease
involves replacing a missing hormone. Which
of the following do you think it is?
a.
b.
c.
d.
e.
n
glucagon
epinephrine
glucocorticoids
antidiuretic hormone (ADH)
thyroid-stimulating hormone (TSH)
In an experiment, researchers removed the
of young mice, and as a result, these mice
were able to accept organ transplants without
rejection.
a. pineal glands
b. thymus glands
c. thyroid glands
d. parathyroid glands
e. adrenal glands
8. Tim once suffered a severe allergic reaction to a
bee sting. The sting caused him to suffer a
near-fatal drop in blood pressure called anaphylactic shock. Now he carries a kit containing a syringe of
, which he can inject to
speed up his heart if he reacts to a bee sting.
a.
b.
c.
d.
e.
insulin
thyroxine
testosterone
calcitonin
epinephrine
2Ag
9. It hasbeenfound that certainsalamandersfail
to go through the normal transformation from
tadpole to adult if thereis a shortageof iodine
in the pond water in which they live. This makes
to manufacture horit impossible for the monesnecessaryfor normal development.
a. thyroid gland
b. posterior pituitary
c. adrenal cortex
d. pineal gland
e. pancreas
10. As a young girl, Maria suffered a head injury
that damaged her pituitary. An injury to the pituitary is particularly seriousbecauseof all the
functions controlled by this gland. As Maria
got older, she and her doctors found that all of
were affected.
the following excepta. metabolic rate
b. growth
c. her menstrual cycle
d. milk production
e. blood calciumlevel
Essay
1. Hypoglycemia is a condition in which blood
sugar drops to abnormally low levels.What
seemsto be the causeof hypoglycemia?Why
would it not be a good idea to try to correct
this problem by eating more sugar?
2. One of the symptoms of severediabetesmellitus is breath that has a sweetish,acetonesmell.
The smell comesfrom by-products of fat breakdown in the body. If another consequenceof
diabetesis excesssugar in the blood, why do
the cells not just use the sugar instead of breaking down fat?
3. A tumor can causeenlargementof the thyroid
gland. How could this result in abnormally
high metabolic rate and body temperature?
How could similar symptoms be produced by
a tumor of the pituitary gland?
4. Somehormones,such as ADH, act on very specific targets (for ADH, the kidney). Other hormones,such as insulin, are able to affect every
cell in the body. Basedon what you have
leamed about how hormones exert their effects
on target cells,speculateas to how somehormones can affect many targets,while other
hormones affect only one.
29O
Chapter26
5. A chemical called dioxin, or TCDD, is produced as a contaminant during some chemical
manufacfuring processes.Trace amounts of
this substancewere present in Agent Orange, a
defoliant sprayed on vegetation during the
Vietnam War. There has been a continuing
controversy over its effectson soldiers exposed
to it during the war. Animal testshave shown
that dioxin can be lethal and can causebirth
defects,cancer,liver and thymus damage,and
immune systemsuppression.But its effectson
humans are unclear, and even animal testsare
uneveni a hamster is not affectedby a dose that
can kill a guinea pig. Researchershave discovered that dioxin exertsits effectslike a steroid
hormone. It entersa cell and binds to a receptor protein, which in turn attachesto the cell's
DNA. How might this mechanismhelp explain
the variety of effectsof dioxin on different
bodv svstemsand in different animals?
Ertending YourKnowledge
1 . Compare communication in the body via nerve
impulses and hormones with everyday communication by telephoneand letter. \rVhatare
the characteristicsof each?In what situations is
eachthe most useful?
2. A survey indicates that over a quarter million
U.S.high school students have used anabolic
steroids,slmthetic derivatives of testosterone.
This number is in addition to the thousandsof
collegeand professional athleteswho have
used thesehormones.Why do athletesuse anabolic steroids?\A/hatare some of the dangers of
steroid use?Do you know anyone who has
used steroids in this way?
3. Do you know someonewho has an endocrine
disorder, such as diabetes?How does that person deal with his or her condition? Have there
been recent discoveriesor developmentsthat
have improved treatment of this condition?