Chapter 45 Flashcards
(360 cards)
1
Q
What are the four mechanisms of cell communication?
A
direct contact; synaptic signaling; endocrine signaling; paracrine signaling
2
Q
What is a hormone?
A
regulatory chemical secreted into extracellular fluid and carried by the blood
3
Q
What is the main advantage of hormones?
A
they can act at a distance from its source
4
Q
Specialized organs that secrete hormones are called
A
endocrine glands
5
Q
What are two organs that additionally secrete hormones?
A
kidney; liver
6
Q
What is the endocrine system?
A
collectively refers to organs, tissues that produce hormones
7
Q
(T/F) The blood carries hormones to every cell in the body.
A
true
8
Q
What must a cell have to be able to respond to a hormone?
A
A cell must have the appropriate receptor to respond.
9
Q
The highly specific interactions between hormones and their receptors enable hormones to be active at
A
remarkably small concentrations, such as 1e-8 or 1e-9 M
10
Q
What is the name for the chemical messengers that are not neurotransmitters or hormones, and where do they act?
A
paracrine regulators; released and act within an organ on nearby cells as local regulators
11
Q
Do paracrine regulators travel through the blood?
A
no
12
Q
What is autocrine signaling?
A
when cells release signaling molecules that affect their own behavior
13
Q
Autocrine signaling is common in (2)
A
the immune system; cancer cells that release growth factors that stimulate their own growth
14
Q
What are pheromones?
A
chemicals released into the environment to communicate among individuals of a single species
15
Q
What do pheromones change?
A
may alter the behavior or physiology of the receiver, but are not involved in the normal metabolic regulation of an animal
16
Q
Molecules aren’t just limited to acting as hormones; they can also act as
A
neurotransmitters
17
Q
Give an example of a molecule that functions as a hormone and as a neurotransmitter that is secreted by the adrenal glands.
A
norepinephrine
18
Q
Neurons secrete a class of hormones carried by the blood that are called
A
neurohormones
19
Q
What secretes antidiuretic hormone?
A
neurons in the brain
20
Q
How can neurons deliver chemical messages beyond the nervous system itself?
A
some specialized regions of the brain contain not only neurotransmitting neurons, but also clusters of neurons producing neurohormones
21
Q
What controls endocrine glands’ secretory activities?
A
nervous system
22
Q
What controls the hormonal secretions of the anterior pituitary gland?
A
hypothalamus
23
Q
What produces the hormones of the posterior pituitary?
A
hypothalamus
24
Q
Is the secretion of hormones always under neural control?
A
No, it can be independent of neural control
25
Give an example of two hormones that are secreted outside of neural control.
insulin from pancreas; aldosterone by adrenal cortex
26
What stimulates the release of insulin from the pancreas?
stimulated by increases in the blood concentrations of glucose
27
What stimulates the release of aldosterone from the adrenal cortex?
stimulated by increases in the blood concentrations of K+
28
Cells in the organs that are part of the endocrine system secrete hormones after synthesis into what?
the extracellular fluid, where it diffuses into surrounding blood capillaries
29
Contrast endocrine and exocrine glands.
Exocrine glands secrete their product into a duct to outside the body or into the gut
30
What are the two basic characteristics of hormones?
must be sufficiently complex to convey regulatory information to targets; must be adequately stable to resist destruction prior to reaching target cells
31
What are the three primary categories of hormones?
peptides and proteins; amino acid derivatives; steroids
32
How many AAs long is antidiuretic acid?
9 amino acids
33
How many AAs long is insulin?
51 amino acids
34
How many AAs long is growth hormones?
191 amino acids
35
Peptides and proteins are composed of
chains of amino acids
36
Amino acid derivatives are hormones manufactured by
enzymatic modification of specific amino acids
37
Amino acid derivatives include hormones secreted by what three structures?
adrenal medulla; thyroid; pineal glands
38
The amino acid derivatives secreted from the adrenal medulla are derived from
tyrosine.
39
What is the name for the group of amino acid derivatives secreted from the adrenal medulla that are derived from tyrosine?
catecholamines
40
Catecholamines include what two classes of hormones?
epinephrine (adrenaline) and norepinephrine (noradrenaline)
41
What are thyroid hormones? (2)
hormones that are derived from tyrosine; secreted by thyroid gland
42
What are two groups of hormones that are derived from tyrosine?
catecholamines; thyroid hormones
43
What secretes melatonin?
pineal gland
44
Melatonin is derived from which amino acid?
tryptophan
45
Describe steroids.
lipids manufactured by enzymatic modifications of cholesterol
46
Steroids are primarily derived from
cholesterol
47
Steroid hormones can be divided into what two classes?
sex steroids; corticosteroids
48
Sex steroids are secreted by (4)
the testes, ovaries, placenta, adrenal cortex
49
Corticosteroids are secreted by
only the adrenal cortex
50
Give 5 examples of steroid hormones.
testosterone; estradiol; progesterone; aldosterone; cortisol
51
Broadly speaking, hormones can be organized into what two categories?
lipophilic; hydrophilic
52
Which two categories/classes of hormones are lipophilic?
steroid hormones; thyroid hormones
53
Which categories/classes of hormones are hydrophilic?
almost everything except steroid hormones, thyroid hormones
54
Hydrophilic hormones are freely soluble in (2)
water; blood
55
The hypothalamus secretes what two hormones?
releasing hormones; inhibiting hormones
56
What is the the target tissue for releasing hormones?
adenohypophysis
57
What is the principal action of releasing hormones?
activates release of adenohypophyseal hormones
58
What is the chemical nature of releasing hormones?
peptides
59
What is the target tissue of inhibiting hormones?
adenohypophysis
60
What is the principal action of inhibiting hormones?
inhibit release of adenohypophyseal hormones
61
What is the chemical nature of inhibiting hormones?
peptides (except prolactin-inhibiting factor, which is dopamine)
62
What is another name for the posterior-pituitary gland?
neurohypophysis
63
What is another name for the neurohypophysis?
posterior-pituitary gland
64
What are the two hormones secreted by the neurohypophysis?
antidiuretic hormone (ADH); oxytocin (OT)
65
What is the target tissue of the antidiuretic hormone?
kidneys
66
What is the principal action of the antidiuretic hormone?
conserves water by stimulating its reabsorption from urine
67
What is the chemical nature of the antidiuretic hormone?
peptide (9 amino acids)
68
What are the target tissues of oxytocin?
uterus; mammary glands
69
What are the principal actions of oxytocin?
in the uterus, stimulates contractions; in the mammary glands, stimulates milk ejection
70
What is the chemical nature of oxytocin?
peptide (9 amino acids)
71
What is another name for the anterior-pituitary gland?
adenohypophysis
72
What is another name for the adenohypophysis?
anterior-pituitary gland
73
What 7 hormones are secreted by the adenohypophysis?
adrenocorticotropic hormone (ACTH); melanocyte-stimulating hormone (MSH); growth hormone (GH); prolactin (PRL); thyroid-stimulating hormone (TSH); luteinizing hormone (LH); follicle-stimulating hormone (FSH)
74
What is the target tissue of the adrenocorticotropic hormone?
adrenal cortex
75
What is the principal action of the adrenocorticotropic hormone?
stimulates secretion of adrenal cortical hormones such as cortisol
76
What is the chemical nature of the adrenocorticotropic hormone?
peptide (39 amino acids)
77
What is the target tissue of the melanocyte-stimulating hormone?
skin
78
What are the principal actions of the melanocyte-stimulating hormone?
stimulates color change in reptiles and amphibians; various functions in mammals
79
What is the chemical nature of the melanocyte-stimulating hormone?
peptide (2 forms: 13 and 22 amino acids)
80
What is the target tissue of the growth hormone?
many organs
81
What is the principal action of the growth hormone?
stimulates growth by promoting bone growth, protein synthesis, and fat breakdown
82
What is the chemical nature of the growth hormone?
protein
83
What is the target tissue of prolactin?
mammary glands
84
What is the principal action of prolactin?
stimulates milk production
85
What is the chemical nature of prolactin?
protein
86
What is the target tissue of the thyroid-stimulating hormone?
thyroid gland
87
What is the principle action of the thyroid-stimulating hormone?
stimulates thyroxine secretion
88
What is the chemical nature of the thyroid-stimulating hormone?
glycoprotein
89
What is the target tissue of the luteinizing hormone?
gonads
90
What are the principal actions of the luteinizing hormone? (2)
in females, stimulates ovulation and corpus luteum formation; in males, stimulates secretion of testosterone
91
What is the chemical nature of the luteinizing hormone?
glycoprotein
92
What is the target tissue of the follicle-stimulating hormone?
gonads
93
What are the principal actions of the follicle-stimulating hormone?
in females, stimulates development of ovarian follices; in males, stimulates spermatogenesis
94
What is the chemical nature of the follicle-stimulating hormone?
glycoprotein
95
What two hormones does the thyroid gland secrete?
thyroid hormones (thyroxine + triiodothyronine); calcitonin
96
What is the target tissue of the thyroid hormones?
most cells
97
What are the principal actions of the thyroid hormones? (2)
stimulates metabolic rate; essential to normal growth and development
98
What is the chemical nature of the thyroid hormones?
amino acid derivative (iodinated)
99
What is the target tissue of calcitonin?
bone
100
What is the principal action of calcitonin?
inhibits loss of calcium from bone
101
What is the chemical nature of calcitonin?
peptide (32 amino acids)
102
What hormone does the parathyroid gland secrete?
parathyroid hormone (PTH)
103
What are the target tissues of the parathyroid hormone? (3)
bone; kidneys; digestive tract
104
What are the principal actions of the parathyroid hormone? (2)
raises blood calcium level by stimulating bone breakdown; stimulates calcium reabsorption in kidneys; activates vitamin D
105
What is the chemical nature of the parathyroid hormone?
peptide (34 amino acids)
106
What two hormones are secreted by the adrenal medulla?
epinephrine (adrenaline); norepinephrine (noradrenaline)
107
What are the target tissues of epinephrine and norepinephrine? (3)
smooth muscle; cardiac muscle; blood vessels
108
What are the principal actions of epinephrine and norepinephrine? (5)
initiates stress responses; raises heart rate, blood pressure, metabolic rate; dilates blood vessels; mobilizes fat; raises blood glucose level
109
What is the chemical nature of epinephrine and norepinephrine?
amino acid derivatives
110
What two hormones does the adrenal cortex secrete?
glucocorticoids (like cortisol); mineralocorticoids (like aldosterone)
111
What is the target tissue of the glucocorticoids?
many organs
112
What are the principal actions of the glucocorticoids? (3)
adaptation to long-term stress; raises blood glucose level; mobilizes fat
113
What is the chemical nature of the glucocorticoids?
steroids
114
What is the target tissue of the mineralocorticoids?
kidney tubules
115
What is the principal action of the mineralocorticoids?
maintains proper balance of Na+ and K+ in blood
116
What is the chemical nature of the mineralocorticoids?
steroid
117
What two hormones are secreted by the pancreas?
insulin; glucagon
118
What are the target tissues of insulin? (3)
liver; skeletal muscles; adipose tissue
119
What are the principal actions of insulin? (2)
lowers blood glucose level; stimulates glycogen, fat, protein synthesis
120
What is the chemical nature of insulin?
peptide (51 amino acids)
121
What are the target tissues of glucagon? (2)
liver; adipose tissue
122
What are the principal actions of glucagon? (2)
raises blood glucose level; stimulates breakdown of glycogen in liver
123
What is the chemical nature of glucagon?
peptide (29 amino acids)
124
What are the two hormones secreted by the ovaries?
estradiol; progesterone
125
What are the target tissues of estradiol? (2)
general; female reproductive structures
126
What are the principal actions of estradiol? (2)
generally, stimulates development of female secondary sex characteristics; in female reproductive structures, stimulates growth of sex organs at puberty and monthly preparations of uterus for pregnancy
127
What is the chemical nature of estradiol?
steroid
128
What are the target tissues of progesterone? (2)
uterus; mammary glands
129
What are the principal actions of progesterone? (2)
in the uterus, completes preparation for pregnancy; in mammary glands, stimulates development
130
What is the chemical nature of progesterone?
steroid
131
What hormone is secreted by the testis?
testosterone
132
What are the target tissues of testosterone?
many organs; male reproductive structures
133
What are the principal actions of testosterone? (2)
in many organs, stimulates development of secondary sex characteristics in males and growth spurt at puberty; in male reproductive structures, stimulates development of sex organs and spermatogenesis
134
What is the chemical nature of testosterone?
steroid
135
What hormone is secreted by the pineal gland?
melatonin
136
What are the target tissues of melatonin? (3)
gonads; brains; pigment cells
137
What is the principal action of melatonin?
regulates biological rhythms
138
What is the chemical nature of melatonin?
amino acid derivative
139
How do hydrophilic hormones activate target cell receptors?
because hydrophilic hormones cannot cross a cell membrane, they must activate target cell receptors from outside the cell membrane
140
How do lipophilic hormones travel in the blood?
lipophilic hormones travel in the blood attached to transport proteins
141
How do lipophilic hormones activate target cell receptors?
they cross the cell membrane and bind to intracellular receptors
142
Eventually, what happens to hydrophilic and lipophilic hormones?
they are destroyed/deactivated after use and are excreted in bile or urin
143
Which hormone is deactivated more rapidly?
hydrophilic hormones are deactivated more rapidly than lipophilic hormones
144
Describe the longevity of hydrophilic and lipophilic hormones.
hydrophilic hormones act over brief periods of time whereas lipophilic hormones act over prolonged periods
145
Where does paracrine regulation occur?
occurs in most organs and among the cells of the immune system
146
What are growth factors?
proteins that promote growth and cell division in specific organs
147
What does the epidermal growth factor do?
activates mitosis of skin and development of connective tissue cells
148
What does the nerve growth factor do?
stimulates growth and survival of neurons
149
What does the insulin-like growth factor do? (2)
stimulates cell division in developing bone; protein synthesis in many other tissues
150
What are cytokines?
growth factors specialized to control cell division and differentiation in the immune system
151
What are neurotropins?
growth factors that regulate the nervous system
152
Damage to the genes coding for growth factors or their receptors can lead to
unregulated cell division and the development of tumors
153
NO can function as a
neurotransmitter
154
NO is produced by
the endothelium of blood vessels
155
How does NO function as a paracrine regulator?
it diffuses to the smooth muscle layer of the blood vessel and promotes vasodilation
156
What is one of the major roles of NO?
control of blood pressure by dilating arteries
157
What does endothelin do?
stimulates vasoconstriction
158
What does bradykinin do?
promotes vasodilation
159
Why is paracrine regulation important in the context of blood vessels?
supplements the regulation of blood vessels by autonomic nerves, enabling vessels to respond to local conditions
160
Describe the structure of a prostaglandin.
20-carbon-long fatty acid that contains a five-membered carbon ring
161
Prostaglandins are derived from
arachidonic acid
162
When is arachidonic acid released?
released from phospholipids in the cell membrane under hormonal or other stimulation
163
(T/F) Prostaglandins are produced in a small number of organs.
False, prostaglandins are produced in almost every organ and participate in a variety of regulatory functions
164
Excessive prostaglandin production may be involved in (3)
premature labor; endometriosis; dysmenorrhea
165
Prostaglandins are involved in (3)
regulating reproductive functions; promoting smooth muscle contractions; lung + kidney regulation
166
In fish, prostaglandins have been found to function as
both a hormone and a paracrine regulator
167
How are prostaglandins involved in pain?
they're produced at locations of tissue damage, where they promote inflammation, swelling, pain, or fever
168
Prostaglandins produced in a fish's ovary can travel to what structure?
can travel to the brain to synchronize associated spawning behavior
169
Give an example of a drug that inhibits prostaglandin synthesis.
aspirin
170
To what class of drugs does aspirin belong to?
nonsteroidal anti-inflammatory drugs (NSAIDs)
171
Give two examples of NSAIDs, other than aspirin.
indomethacin; ibuprofen
172
NSAIDs act to inhibit what two enzymes?
cyclooxygenase-1 and cyclooxygenase-2
173
The inhibition of which enzyme contributes to anti-inflammatory effects?
cyclooxygenase-2, which is necessary for the production of prostaglandins from arachidonic acid
174
What are the side effects of the inhibition of cyclooxygenase-1? (2)
gastric leeding; prolonoged clotting time
175
How do recently-developed pain relievers inhibit COX-1 and COX-2?
they selectively inhibit COX-2 but not COX-1
176
Are COX-2 inhibitors more effective for pain than other NSAIDs?
no
177
What is another lipophilic hormone, other than steroid or thyroid hormones?
the retinoids (vitamin A)
178
Broadly speaking, prostaglandins are what type of regulator?
prostaglandins are a diverse group of paracrine regulators
179
Ultimately, hormones that enter the cell are ultimately destined for what structure?
the nucleus
180
What are two ways that hormones entering the cell go to the nucleus?
they can bind to receptors in the cytoplasm and move as a complex into the nucleus; they can directly travel into the nucleus and then bind to a receptor
181
The hormone-receptor complex, once in the nucleus, undertakes what task?
binds to specific regions of DNA called hormone response elements
182
What are hormone response elements?
specific regions of DNA to which hormone-receptor complexes bind
183
Receptors that bind to hormones and facilitate DNA transcription are known as
hormone-activated transcription factors
184
Describe the proteins that result from hormone-activated transcription.
often have activity that changes the metabolism of the target cell in a specific fashion
185
What happens when estrogen binds to its receptors in the liver cells of chickens?
the protein vitellogenin is produced, which is transported to the ovary to form the yolk of eggs
186
What happens when thyroid hormones bind to its receptors in the anterior pituitary of humans?
inhibition of the expression of the gene for thyrotropin (a negative feedback mechanism)
187
How often can it take for the effect of lipophilic hormone stimulation to be apparent in target cells?
it can take several hours
188
Which classes of hormones are too large or too polar to cross the plasma membrane of their target cells? (2)
peptides/protein/glycoprotein hormones; catecholamine hormones
189
Where do large or hydrophilic hormones bind to the cell?
they bind to receptor proteins located on the outer surface of the plasma membrane
190
The cellular response of a hydrophilic/large hormone binding to a surface receptor is called
signal transduction
191
The cellular response of a hydrophilic/large hormone binding to a surface receptor is made possible by
intracellular enzymes called protein kinases
192
What are protein kinases?
critical regulatory enzymes that activate or deactivate intracellular proteins by phosphorylation
193
For which hormone is its receptor itself a kinase?
insulin
194
What happens when insulin binds to its receptor that is itself a kinase?
results in the placement of glucose transport proteins in the plasma membrane, which enables glucose to enter cells
195
In other peptide hormones, such as the growth hormone, how are receptors activated?
The receptor itself is not a kinase, but the hormone-bound receptor recruits and activates intracellular kinases, which then initiate cellular response
196
Hydrophilic hormones, in addition to activating receptors on target cells and activating protein kinases, can also initiate cellular response through what system?
second-messenger systems
197
Give an example of a hydrophilic hormone that makes use of the second messenger system.
epinephrine
198
How does the second-messenger system work?
the interaction between the hormone and its receptor activates mechanisms in the plasma membrane that increase the concentration of second messengers within the target cell cytoplasm
199
In the 1960s, Earl Sutherland showed
that activation of epinephrine receptors on liver cells increases intracellular levels of cAMP (a second messenger)
200
What was the first second messenger system to be described?
the epinephrine-cAMP second messenger system
201
What are two additional lipid messengers other than cAMP?
inositol triphosphate (IP3) and diacylglycerol (DAG)
202
Do receptors that activate second messengers manufacture the second messenger themselves?
No, they don't
203
How do receptors that activate second messengers induce production of second messengers?
The binding of the hormone to its receptor causes G proteins to shuttle within the plasma membrane from the receptor to the second-messenger-generating enzyme
204
How do G proteins work in the context of epinephrine? (2)
G proteins activate an enzyme called adenylyl cyclase, which catalyzes the formation of the second messenger cAMP from ATP; cAMP then diffuses within the cytoplasm and binds/activates protein kinases
205
What is the effect of cAMP dependent protein kinases in liver cells?
activates enzymes that convert glycogen into glucose
206
What is the effect of cAMP dependent protein kinases in cardiac muscle cells?
increase in the rate and force of cardiac muscle contraction
207
The cellular response to a hormone primarily depends on
the type of G protein activated by the hormone's receptor
208
Can a single hormone have distinct actions in two different cell types?
Yes, if the receptors in those two cells are linked to different G proteins
209
T/F: the binding of a hydrophilic hormone is irreversible.
False, the binding of a hydrophilic hormone is reversible and very brief
210
What deactivates hydrophilic hormones following binding?
The target cell deactivates the hormone and also contains specific enzymes that rapidly deactivate second messengers and protein kinases
211
What are the enzymes involved in the cAMP-dependent protein kinase stimulation of cardiac muscle cells?
a G protein is linked to the IP-3 generating enzyme phospholipase C, and IP-3 regulates the release of Ca2+ ions, which causes muscle contractions
212
What is another name for the pituitary gland?
hypophysis
213
What is another name for the hypophysis?
pituitary gland
214
Describe the location of the pituitary gland.
hangs by a stalk from the hypothalamus at the base of the brain posterior to the optic chasm
215
The pituitary gland is composed of which two parts?
anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis)
216
What are the fibrous and glandular parts of the pituitary gland?
the fibrous part is the posterior pituitary and the glandular part is the anterior pituitary
217
T/F: The anterior pituitary and posterior pituitary glands have different embryonic origins.
True: the anterior pituitary and the posterior pituitary have different embryonic origins.
218
T/F: The anterior pituitary and posterior pituitary glands are regulated by different control system.s
True: the anterior pituitary and the posterior pituitary are regulated by different control systems
219
Why does the posterior pituitary appear fibrous?
because it contains axons that originate in cell bodies within the hypothalamus and that extend along the stalk of the pituitary as fibers
220
How does the fibrous nature of the posterior pituitary form during development?
As the floor of the third ventricle of the brain forms the hypothalamus, part of the neural tissue grows downward to produce the posterior pituitary
221
What is diuresis?
urine production
222
What is the relationship between ADH and diuresis?
ADH inhibits diuresis
223
What is the relationship between alcohol and ADH?
alcohol inhibits ADH secretion, which leads to frequent urination
224
In mammals, oxytocin is responsible for what ejection reflex?
oxytocin is responsible for the milk ejection reflex, in which sensory receptors in the nipples send impulses to the hypothalamus and trigger the release of oxytocin
225
T/F: Does oxytocin secretion continue after childbirth in women?
True, continues after childbirth in women who are breastfeeding
226
What is a related posterior pituitary hormone to oxytocin?
arginine vasotocin
227
What does arginine vasotocin do? (2)
acts like oxytocin but in nonmammalian species; in chickens and sea turtles, arginine vasotocin activates oviduct contraction during egg laying
228
Beyond reflexes, how is oxytocin involved in behavior?
it is an important regulator of reproductive behavior in men and women
229
Give two examples of how oxytocin regulates reproductive behavior.
promotes pair bonding; regulates sexual responses like arousal and orgasm
230
For reproductive behavior, oxytocin behaves much like a
a neurotransmitter in a paracrine fashion inside the CNS
231
Where are ADH and oxytocin actually produced, and why is this confusing?
ADH and oxytocin are actually produced by neuron cell bodies located in the hypothalamus; they're transported along the axon tract between the hypothalamus and the posterior pituitary and are stored in the posterior pituitary
232
What kind of reflex secretes ADH and oxytocin?
neuroendocrine reflex, because both the nervous and endocrine systems are involved
233
How many hormones does the anterior pituitary produce?
seven
234
Where does the anterior pituitary develop from?
develops from a pouch of epithelial tissue that pinches off from the roof of the embryo's mouth
235
T/F: the anterior pituitary is part of the nervous system.
FALSE, the anterior pituitary is NOT part of the nervous system
236
Several hormones of the anterior pituitary are collectively referred to as
tropic hormones (tropins)
237
What do tropic hormones do?
tropic hormones act on other endocrine glands to stimulate secretion of hormones produced by the target gland
238
The anterior pituitary secretes what three structurally similar families of hormones?
peptide hormones; protein hormones; glycoprotein hormones
239
What is another name for the growth hormone?
somatotropin
240
Does the growth hormone stimulate bone growth directly?
No, it stimulates bone growth indirectly
241
How many amino acids long are protein hormones?
a single chain of approximately 200 amino acids
242
Other than stimulating milk production, what else does prolactin do? (3)
regulation of water/ion transport across epithelia; stimulation of organs that nourish the young; activation of parental behaviors
243
What are the largest and most complex hormones known?
glycoprotein hormones
244
Describe the structure of glycoprotein hormones.
dimers, containing alpha/beta subunits each 100 amino acids in size with covalently linked sugar residues
245
Which subunit of the glycoprotein hormone is common to all three glycoprotein hormones?
alpha subunit - the beta subunit differs which is what gives these hormones specificity
246
What is another name for the thyroid-stimulating hormone?
thyrotropin
247
FSH and LH are collectively referred to as
gonadotropins
248
What structure controls the production and secretion of anterior pituitary hormones?
hypothalamus
249
How does the hypothalamus control anterior pituitary secretions?
control is exerted hormonally rather than by nerve axons, using releasing hormones and inhibiting hormones
250
What are the two types of hormones secreted by neurons in the hypothalamus?
releasing hormones and inhibiting hormones
251
Describe and name the system that circulates releasing and inhibiting hormones from the hypothalamus.
the two hormones diffuse into blood capillaries at the base of the hypothalamus, then drain into small veins that run to the anterior pituitary; called the hypothalamohypophyseal portal system
252
What is a portal system?
circulatory structure in which two capillary beds are linked by veins
253
Which hormone stimulates the release of thyroid-stimulating hormone?
thyrotropin-releasing hormone (TRH)
254
Which hormone stimulates the release of adrenocorticotropic hormone?
corticotropin-releasing hormone (CRH)
255
Which hormone stimulates the release of FSH and LH?
gonadotropin-releasing hormone (GnRH)
256
Which hormones stimulates the release of the growth hormone?
growth hormone releasing hormone (GHRH)
257
Which hormones stimulate the release of prolactin?
TRH, oxytocin, vasoactive intestinal peptide
258
Which hormone inhibits the release of growth hormone?
somatostatin (a.k.a. growth hormone inhibiting hormone - GHIH)
259
Which hormone inhibits the secretion of prolactin?
prolactin-inhibiting factor (PIF) which is actually dopamine
260
Which hormone inhibits the secretion of melanocyte-stimulating hormone?
MSH-inhibiting hormone (MIH)
261
The hypothalamus and anterior pituitary are under what kind of feedback control?
negative feedback control
262
TSH causes the thyroid gland to release
thyroxine
263
What does thyroxine do?
affect metabolic rate
264
Give an example of a hormone that performs negative feedback inhibition on the anterior pituitary and hypothalamus
thyroxine
265
What specific element is needed for the thyroid gland to produce thyroxine?
iodine
266
What kind of areas lack iodine?
areas distant from seacoasts
267
If there is insufficient iodine and therefore insufficient thyroxine, what happens?
the hypothalamus/anterior pituitary release more TRH and TSH
268
What happens with elevated levels of TSH resulting from an iodine deficiency?
the cells enlarge to attempt to produce more thyroxine but the thyroid gland keeps getting bigger and bigger - a condition known as goiter
269
What is ovulation?
explosive release of a mature egg (oocyte) from an ovary
270
As the oocyte grows, what hormones are released?
as the oocyte grows, follicle cells surrounding it produce estrogen, which eventually tells the hypothalamus that the oocyte is ready for ovluation
271
What results after peak estrogen levels?
surge of LH from the anterior pituitary, which causes the release of the oocyte into the oviduct
272
When is the ovulation cycle's positive feedback mechanism terminated?
the remaining tissue from the ovarian follicle forms the corpus luteum, which secretes estrogen and progesterone which inhibit FSH and LH
273
What is hypophysectomy?
surgical removal of the pituitary gland
274
Which anterior pituitary glands work through direct effects? (3)
growth hormone; prolactin; MSH
275
Which anterior pituitary glands work through indirect effects? (4)
ACTH, TSH, LH, FSH
276
Gigantism is caused by
the excessive secretion of GH in a growing child
277
Pituitary dwarfism is caused by
a deficiency in GH secretion during childhood
278
The growth hormone stimulates what factors to promote bone growth?
the growth hormone stimulates the production of insulin-like growth factors, which are produced by the liver and bone in response to GH stimulation
279
What do the insulin-like growth factors do?
stimulate cell division in the epiphyseal growth plates, and thus elongation of the bones
280
How does GH function in adults?
regulates protein, lipid, and carbohydrate metabolism
281
What is ghrelin?
peptide hormone released by the stomach between meals that is a potent stimulator of GH release, which implies an important linkage between nutrient intake and GH production
282
How does excessive GH secretion manifest in adults?
acromegaly, which can include a protruding jaw, elongated fingers, or thickening of skin
283
In amphibians, what does prolactin do?
promotes transformation of salamanders from terrestrial forms to aquatic breeding adults
284
The thyroid and parathyroid glands are derived from
primitive pharynx, which is the most anterior segment of the digestive tract
285
Which two glands are derived from the primitive pharynx?
thyroid and parathyroid glands
286
Where is the thyroid gland found? (2)
anterior to the heart; in humans, shaped like a bow tie and below the Adam's apple
287
What are the only molecules in the body to contain iodine?
thyroid hormones (thyroxine contains 4 I atoms, triiodothyronine contains 3 I atoms)
288
Adults with hypothyroidism suffer from
low metabolism due to underproduction of thyroxine, which basically means a reduced ability to make use of carbs and fats
289
What are the symptoms of hyperthyroidism? (3)
fatigue, overweight, chills
290
What is the effect of hypothyroidism in children? (3)
impairs growth; impairs brain development; impairs reproductive maturity
291
What are the symptoms of hyperthyroidism? (4)
weight loss; nervousness; high metabolism; overheating
292
Thyroid hormones regulate enzymes controlling what types of metabolism?
regulate enzymes controlling carbohydrate and lipid metabolism in most cells
293
In developing humans, what is the relationship between thyroid hormones and the CNS?
thyroid hormones promote growth of neurons and stimulate maturation of the CNS
294
What is cretinism?
severe mental retardation resulting from hypothyroidism
295
Why are thyroid hormones important in amphibians?
they direct metamorphosis from an aquatic larva to a terrestrial carnivore
296
The thyroid/parathyroid glands work with ___ to regulate calcium homeostasis.
vitamin D
297
The thyroid/parathyroid glands work with vitamin D to regulate
calcium homeostasis
298
Calcitonin may have an important role in
bone remodeling in rapidly growing children
299
The parathyroid gland is composed of
four small glands attached to the thyroid.
300
A significant fall in blood Ca2+ levels can lead to
severe muscle spasms
301
PTH stimulates osteoclasts to
dissolve calcium phosphate crystals of the bone matrix and release Ca2+ into the blood
302
PTH stimulates the kidneys to
reabsorb Ca2+ from the urine, which leads to the activation of vitamin D
303
Vitamin D is produced in the
skin from a cholesterol derivative in response to UV light
304
Vitamin D is a derivative of
cholesterol
305
How does the Vitamin D molecule become activated?
gains one OH group from an enzyme in the liver, gains another OH group from an enzyme in the kidneys (stimulated by PTH)
306
What is the name for the active form of Vitamin D?
1,25-dihydroxyvitamin D.
307
What does the activated Vitamin D hormone do?
stimulates intestinal reabsorption of Ca2+ and helps raise Ca2+ blood levels to properly mineralize bone
308
What is rickets?
a condition of poor bone formation, caused by a deficiency in vitamin D
309
Where are the adrenal glands located?
just above each kidney
310
Each adrenal gland is composed of (2)
an inner portion called the adrenal medulla and an outer layer called the adrenal cortex
311
From where does the adrenal medulla receive neural input?
axons of the sympathetic division of the autonomic nervous system
312
The hormones secreted from the adrenal cortex are all ____ and are referred to collectively as ______.
they are all steroids and are collectively referred to as corticosteroids
313
What does cortisol do?
acts to maintain glucose homeostasis
314
In mammals, hormones that maintain glucose homeostasis are called
glucocorticoids
315
The secretion of glucocorticoids is regulated by
ACTH from the anterior pituitary
316
What do glucocorticoids do?
stimulate breakdown of muscle protein into amino acids, which are carried by blood to liver; stimulate liver to produce enzymes needed for gluconeogenesis
317
What is gluconeogenesis?
conversion of amino acids into glucose
318
When is glucose synthesis from protein especially important?
during long periods of fasting or exercise
319
Glucocorticoids are secreted in large amounts in response to
stress
320
What is prednisone?
cortisol derivative used as an anti-inflammatory agent
321
What is the other major corticosteroid, apart from glucocorticoids?
aldosterone
322
Aldosterone is classified as a
mineralocorticoid because it regulates mineral balance
323
What activates the secretion of aldosterone? (2)
activated by angiotensin II, a product of the renin-angiotensin system; high blood K+
324
What are aldosterone's primary actions? (2)
reabsorbs Na+ from urine in kidneys; excretes K+ into urine in kidneys
325
What connects the pancreas to the duodenum?
pancreatic duct
326
What does the pancreas secrete?
bicarbonate ions and digestive enzymes into small intestine through the pancreatic duct
327
Insulin is secreted by
the beta cells of the islets of Langerhans
328
Glucagon is secreted by
the alpha cells of the islets of Langerhans
329
When a person eats carbs, what happens to blood glucose?
blood glucose rises
330
When blood glucose rises, what happens? (2)
secretion of insulin by beta cells is activated; secretion of glucagon by the alpha cells is inhibited
331
Insulin promotes the cellular uptake of
glucose into the liver, muscle, and fat cells
332
Insulin activates the storage of
glucose as glycogen in the liver and muscle or as fat in fat cells
333
What happens to insulin and glucagon between meals?
insulin secretion decreases and glucagon secretion increases, which promotes hydrolysis of stored glycogen or fat
334
T/F: insulin is the only hormone that promotes movement of glucose from blood into cells.
true, insulin is the only hormone that promotes movement of glucose from blood into cells.
335
Give another names for type I diabetes.
insulin-dependent diabetes mellitus
336
People with type I diabetes lack
insulin-secreting beta cells and thus produce no insulin
337
How do we treat type I diabetes?
insulin injections
338
Why must insulin be injected?
because it's a peptide, if taken orally it would be digested
339
What is more common, type I or type II diabetes?
type II diabetes
340
Give another name for type II diabetes.
noninsulin-dependent diabetes mellitus.
341
What happens in type II diabetes?
patient has normal insulin levels, but cells have a reduced sensitivity to insulin
342
What percentage of diabetes cases are type II diabetes?
90%
343
Where is the pineal gland located?
roof of the third ventricle of the brain
344
The pineal gland evolved from
a medial light-sensitive eye
345
The pineal eye is still present in
primitive fish and some modern reptiles
346
Describe melatonin levels during various times o the day.
Melatonin levels in the blood increase in darkness and fall during daytime.
347
The secretion of melatonin is regulated by
the suprachiasmatic nucleus (SCN) of the hypothalamus
348
The suprachiasmatic nucleus functions as
the major biological clock in vertebrates
349
Where does T cell production occur in vertebrates?
thymus
350
The right atrium of the heart secretes
atrial natriuretic hormone
351
What does atrial natriuretic hormone do? (2)
stimulates kidneys to excrete salt and water in the urine; acts antagonistically to aldosterone
352
The kidneys independently secrete the hormone
erythropoietin
353
What is erythropoietin?
hormone that stimulates bone barrow to produce red blood cells
354
Prior to insect molting, neurosecretory cells on the surface of the insect brain secrete
prothoracicotropic hormone (PTTH), a small peptide
355
What does prothoracicotropic hormone do?
stimulates a gland in the thorax called the prothoracic gland to produce molting hormone
356
Give another name for the molting hormone.
ecdysone
357
What does ecdysone do?
high levels of edysone bring out the biochemical conditions for molting to occur
358
What does DES stand for?
diethylstilbestrol
359
What is DES?
synthetic estrogen given to pregnant women from 1940 to 1970 to prevent miscarriages
360
Why was DES infamous?
discovered that daughters exposed to DES had a higher chance of developing cervical cancer later in life
