ENDOCRINE SYSTEM Flashcards
1
Q
primary regulators of the coordination of cell activities
A
Chemical messengers of nervous and endocrine system
2
Q
allow cells to communicate with each other to regulate body activities
A
Chemical messengers
3
Q
the controlled release of chemicals from a cell
A
secretion
4
Q
stimulates the cell that originally secreted it
A
Autocrine chemical messengers (ex. Eicosanoids; those secreted by white blood cells during an infection)
5
Q
(T/F) the total number of white blood cells increases rapidly
A
T - Several types of white blood cells can stimulate their own replication
6
Q
act locally on neighboring cells that are secreted by one cell type into the extracellular fluid and affect surrounding cells
A
Paracrine chemical messengers (ex. histamine, Somatostatin, eicosanoids)
7
Q
stimulates vasodilation in nearby blood vessels
A
histamine
8
Q
widening of blood vessels as a result of the relaxation of the blood vessel’s muscular walls and a mechanism to enhance blood flow to areas of the body that are lacking oxygen and/or nutrients
A
Vasodilation
9
Q
chemical messengers secreted by neurons that activate an adjacent cell, whether it is another neuron, a muscle cell, or a glandular cell
A
Neurotransmitters (ex. Acetylcholine, epinephrine)
10
Q
secreted into the bloodstream by certain glands and
cells
A
Endocrine chemical messengers
11
Q
composed of endocrine glands and specialized endocrine cells located throughout the body
A
endocrine system (ductless release)
12
Q
very small amounts of chemical messengers
A
hormones
13
Q
Hormones circulate through the bloodstream to specific
sites called?
A
target tissues, or effectors
14
Q
endo in Greek means?
A
within
15
Q
krino means?
A
to secrete
16
Q
have ducts that carry their secretions to the outside
of the body, or into a hollow organ
A
Exocrine glands (ex. secretions of saliva, sweat, breast milk, and
digestive enzymes)
17
Q
study of the endocrine system
A
endocrinology
18
Q
neuron’s chemical messenger which enters the bloodstream where it functions as a hormone
A
neuropeptides, or neurohormones (ex. oxytocin)
19
Q
hormones secreted by most endocrine glands can be described as
A
amplitude-modulated signals (concentration)
20
Q
the all-or-none action potentials carried along axons can be described as
A
frequency-modulated signals (frequency)
21
Q
hormon in Greek means?
A
set into motion
22
Q
General Characteristics of Hormones (3)
A
Stability
Communication
Distribution
23
Q
(T/F) Larger, more complex hormones are more stable
A
T
24
Q
(T/F) simpler hormones are less stable
A
T
25
A hormone’s life span
half-life
26
amount of time it takes for 50% of the circulating hormone
to be removed from the circulation and excreted.
half-life
27
thyrotropin-releasing hormone (TRH)
short half-life
28
cortisol
longer half-life
29
(T/F) Small, water- soluble hormones are quickly digested by hydrolytic enzymes in the blood and are easily filtered from the blood in the kidneys
T
30
(T/F) lipid-soluble hormones, have low solubility in the blood plasma
T
31
Hormones requiring a transport chaperone bind to blood proteins
binding proteins (protects water-soluble hormones from degradation by hydrolytic enzymes and from being filtered from the blood in the kidney; causes lipid-soluble hormones to become more water-soluble)
32
Once hormones attach to a binding protein, they are then called
bound hormones
33
(T/F) The binding of hormones to binding proteins is reversible
T
34
Once the hormones detach from the binding protein,
they are then called
free hormones
35
(T/F) Hormones that attach to binding proteins tend to have longer half-lives than hormones that do not require binding proteins
T
36
two chemical categories of hormones based on chemical behavior
lipid-soluble hormones
water-soluble hormones
37
nonpolar and include steroid hormones, thyroid hormones, and fatty acid derivative hormones, such as certain eicosanoids
Lipid-Soluble Hormones (ex. Steroids (all cholesterol-based)
Testosterone, aldosterone, thyroxine)
38
lipid-soluble hormones are removed from the
circulation when specific enzymes in the liver attach water-soluble molecules to the hormones,
conjugation
39
polar molecules: they include protein
hormones, peptide hormones, and most amino acid derivative
hormones
Water-Soluble Hormones (ex. Proteins, Insulin, Peptides, Amino Acid Derivatives; Epinephrine)
40
many of these circulate as free hormones
water-soluble hormones
41
The three main patterns of hormone secretion
chronic (constant; thyroid hormones)
acute (Irregular; epinephrine)
episodic (intervals; steroid reproductive hormones)
42
lipid-soluble hormones exhibit the two regular secretion patterns
(chronic and episodic)
43
water-soluble hormones tend to exhibit the secretion pattern __
acute (sometimes episodic)
44
Three types of stimuli regulate hormone release:
humoral stimuli (circulate in blood)
neural stimuli (neurotransmitters into synapses)
hormonal stimuli (hormones stimulate the secretion of other hormones)
45
a term usually reserved for hormones from the hypothalamus
releasing hormones
45
hormones from the anterior pituitary gland,
tropic hormones
46
Three types of stimuli regulate hormone inhibition:
humoral stimuli
neural stimuli
hormonal stimuli
46
hormones from the hypothalamus that prevent the
secretion of tropic hormones from the pituitary gland
inhibiting hormones
46
Two major mechanisms maintain hormone levels in the blood
within a homeostatic range:
negative feedback and positive feedback
47
the hormone’s secretion is inhibited by the hormone itself once blood levels have reached a certain point and there is adequate hormone to
activate the target cell.
Negative feedback (self-limiting system)
ex. thyroid hormones inhibit the
secretion of TRH from the hypothalamus and TSH from the
anterior pituitary
48
hormones promote the further synthesis and secretion of the tropic hormone in addition to stimulating their target cell.
Positive feedback (self-propagating system)
ex. prolonged estrogen stimulation
promotes a release of luteinizing hormone
49
target cell proteins
receptors
50
specific portion of each receptor molecule where a hormone bind is called
receptor site
51
tendency for each type of hormone to bind to one type
of receptor, and not to others
specificity
52
drug that binds to a hormone receptor and activates
agonist
53
A drug that binds to a hormone receptor and inhibits
its action
antagonist
54
Desensitization occurs when the number
of receptors rapidly decreases after exposure to certain hormones
down-regulation
55
results in an increase in the rate of receptor synthesis in the target cells,
which increases the total number of receptor molecules in a cell
Up-regulation
56
Classes of Receptors
1. Lipid-soluble hormones bind to nuclear receptors.
2. Water-soluble hormones bind to membrane-bound receptors.
57
proteins that extend
across the plasma membrane, with their hormone-binding sites
exposed on the plasma membrane’s outer surface
membrane-bound receptors
58
sequences in the DNA called
hormone- response elements
59
The combination of the hormone and its receptor forms
a
transcription factor
60
when the hormone-receptor
complex binds to the hormone-response element, it activates the
transcription of ___ which codes for proteins.
messenger ribonucleic acid (mRNA)
61
Nuclear receptors have portions that allow them to bind to the DNA
in the nucleus once the hormone is bound:
The hormone-receptor complex activates genes, which in turn
activate the DNA to produce mRNA.
The mRNA increases the synthesis of certain proteins that produce
the target cell’s response.
62
(T/F) Nuclear receptors cannot respond immediately, because it takes time to produce the mRNA and the protein
T
63
produced inside a cell once a hormone or another chemical messenger binds to certain membrane-bound receptors
intra cellular mediator
64
an enzyme that converts ATP to cAMP
adenylate cyclase
65
functions as a second messenger, an intracellular mediator that
carries out cellular metabolic processes in response to hormonal activation
Cyclic AMP
66
enzymes that regulate the
activity of other enzymes by attaching phosphates to them, a
process called phosphorylation
protein kinase
67
breaks down cAMP to AMP
phosphodiesterase
68
Membrane-Bound Receptors and Signal
Amplification
1. Membrane-bound receptors activate a cascade of events once the
hormone binds.
2. Some membrane-bound receptors are associated with membrane
proteins called G proteins.
■ Hormone binds to a membrane-bound receptor, and G proteins are
activated.
■ The α subunit of the G protein binds to ion channels and causes
them to open or change the rate of synthesis of intracellular mediators,
such as cAMP, cGMP, IP3, and DAG.
3. Intracellular enzymes can be activated directly, which in turn causes
the synthesis of intracellular mediators, such as cGMP, or adds a
phosphate group to intracellular enzymes, which alters their activity.
4. Second-messenger systems act rapidly, because they act on already
existing enzymes to amplify the signal.
69
FUNCTIONS OF ENDOCRINE SYSTEM
1. Regulation of metabolism
2. Control of food intake and digestion
3. Modulation of tissue development
4. Regulation of ion levels
5. Control of water balance
6. Changes in heart rate and blood pressure
7. Control of blood glucose and other nutrients
8. Control of reproductive functions
9. Stimulation of uterine contractions and milk release
10. Modulation of immune system function. The endocrine system
helps control the production of immune cells
70
secretes nine major hormones that regulate numerous body functions and the secretory activity of several other endocrine glands.
pituitary gland
71
regulates the secretory activity of the pituitary gland in
response to other hormones, sensory information, and emotions.
hypothalamus
72
connected to the base of the brain, just inferior to the hypothalamus; rests in the sella turcica (depression) of the sphenoid bone and is roughly the size of a pea
pituitary gland
73
stalk of tissue that connects the pituitary gland to the
hypothalamus
infundibulum
74
The pituitary gland is divided into which two lobes?
posterior pituitary gland, or neurohypophysis
anterior pituitary gland, or adenohypophysis
75
is called the neurohypophysis because it is
continuous with the hypothalamus in the brain
posterior pituitary (neural tissues)
76
Because the posterior pituitary is a part of the nervous system, its hormones are called?
neuropeptides, or neurohormones
77
develops as an outpocketing of the roof of
the embryonic oral cavity called the pituitary diverticulum, or
Rathke pouch
anterior pituitary (epithelial tissues)
78
not functional in adult humans
pars intermedia
79
a circulatory system
portal systrem
80
a circulatory system
portal system
81
one of the major portal systems in the body
hypothalamohypophysial portal system
82
provides a means by which the hypothalamus, using
neurohormones as chemical messengers, regulates the secretory
activity of the anterior pituitary
hypothalamohypophysial portal system
82
HORMONES OF HYPOTHALAMUS (8)
Growth hormone–releasing
hormone (GHRH)
Growth hormone–inhibiting
hormone (GHIH), or somatostatin
Thyrotropin-releasing hormone (TRH)
Corticotropin-releasing hormone
(CRH)
Gonadotropin-releasing hormone
(GnRH)
Prolactin-releasing hormone (PRH)
Prolactin-inhibiting hormone (PIH)
83
HORMONES OF POSTERIOR PITUITARY (2)
Antidiuretic Hormone (vasopressin)- a water conservation hormone that also constricts blood vessels and raises blood pressure when large
amounts are released
Oxytocin - an important reproductive hormone; increased uterine contractions; increased milk expulsion from mammary glands; unclear function in males
84
HORMONES OF ANTERIOR PITUITARY (6)
Growth hormone (GH), or somatotropin - Increased growth in tissues; increased amino acid uptake and protein synthesis; increased breakdown of lipids and release of fatty acids from cells; increased glycogen synthesis and increased blood glucose levels; increased somatomedin production
Thyroid-stimulating hormone (TSH) - Increased thyroid hormone secretion
Adrenocorticotropic hormone (ACTH) - Increased glucocorticoid hormone secretion
Luteinizing hormone (LH) - Ovulation and progesterone production in ovaries; testosterone synthesis and support for sperm cell production in testes
Follicle-stimulating hormone (FSH) - Follicle maturation and estrogen secretion in ovaries; sperm cell production in testes
Prolactin - Milk production in lactating women; increased response of follicle to LH and FSH; unclear function in males
85
Increased lipid breakdown
Lipotropins
86
Analgesia in the brain; inhibition of gonadotropin-releasing
hormone secretion
β endorphins
87
Chronic hyposecretion, or insufficient secretion, of GH in
infants and children lead to a condition called
pituitary dwarfism
88
There are two types of pituitary dwarfism:
(1) GH and other anterior pituitary hormones are
secreted in reduced amounts (additional disorders; 2/3)
(2) GH secretion is reduced, and the secretion of other anterior pituitary hormones is closer to normal (no additional; 1/3)
89
Chronic hypersecretion of GH before the epiphyseal plates
have ossified causes exaggerated and prolonged growth in long bones,
a condition called
gigantism (childhood)
90
In adults, chronically elevated GH levels result in
acromegaly (No height increase occurs because the epiphyseal
plates have ossified)
91
binds to membrane-bound receptors on skin melanocytes and stimulates
increased melanin deposition in the skin.
Melanocyte-stimulating hormone (MSH)
92
are glycoprotein hormones capable of promoting the growth and function of the gonads, the ovaries and testes.
Gonadotropins
93
composed of two lobes connected by a narrow band of thyroid
tissue called the isthmus and is one of the largest endocrine glands
thyroid gland
94
small spheres whose walls are composed of a single layer of
cuboidal epithelial cells
follicles
95
The center of each
thyroid follicle is filled with a gelatinous material called
colloid (composed of a highly concentrated protein called
thyroglobulin)
96
stores a huge amount of thyroid hormones (Storage of such a large amount of hormone is unique to the thyroid gland.)
thyroglobulin
97
secretes calcitonin
parafollicular cells
98
plays a role in reducing
the concentration of calcium in the body fluids when calcium
levels become elevated
calcitonin
99
THYROID HORMONES (2)
triiodothyronine or T3 (10%) & tetraiodothyronine or T4/thyroxine (80%) - Increased metabolic rate; increased protein synthesis; essential for normal growth and maturation
Calcitonin (10%) - Decreased rate of breakdown of bone by osteoclasts; prevention of a large increase in blood Ca2+ levels
100
should be consumed by humans to support thyroid hormone synthesis
iodine
101
Causes inadequate T3 and T4 synthesis, which results in elevated thyroid-stimulating hormone (TSH) secretion
Iodine deficiency
102
Inhibit T3 and T4 synthesis; found in certain drugs and in small amounts in certain plants, such as cabbage
Goitrogenic (goiter-causing) substances
103
Caused by maternal iodine deficiency or congenital errors in thyroid hormone synthesis
Neonatal hypothyroidism
104
Results from lack of TSH secretion
Pituitary insufficiency
105
Autoimmune disease in which thyroid hormone secretion can be normal or depressed
Hashimoto disease
106
Partial or complete surgical removal or drug-induced destruction of the thyroid gland as a treatment for Graves
disease (hyperthyroidism)
Lack of thyroid gland
107
Characterized by goiter and exophthalmos
Graves disease
108
Result in either normal secretion or hypersecretion of thyroid hormones (rarely hyposecretion)
Tumors—benign adenoma or cancer
109
Produces painful swelling of the thyroid gland with normal or slightly increased T3 and T4 production
Thyroiditis—a viral infection
110
Thyroid storm Sudden release of large amounts of T3 and T4; caused by surgery, stress, infections, or other, unknown factors
Thyroid storm
111
abnormal enlargement of the thyroid gland
goiter
112
results when dietary
iodine intake is so low that there is not enough iodine to synthesize T3 and T4
iodine-deficiency goiter
113
most common preventable cause of mental defects,
iodine-deficiency diseases
114
may be the most common endemic disease on the planet
hypothyroidism
115
secretes excess T3 and T4, and it can result from
elevated TSH secretion or elevated TSH-like immunoglobulin
toxic goiter
116
most common cause of hyperthyroidism
Graves disease
117
usually embedded in
the posterior part of each lobe of the thyroid gland
parathyroid glands
118
parathyroid glands are made up of two cell types:
chief cells (secrete parathyroid hormone,)
oxyphils
119
polypeptide hormone that is important in regulating calcium levels in body fluids
Parathyroid hormone (PTH), also called parathormone
120
Increased rate of breakdown of bone by osteoclasts;
increased reabsorption of Ca2+in kidneys; increased absorption of Ca2+from the small intestine; increased vitamin D synthesis; increased blood Ca2+ levels
Parathyroid hormone (PTH)
121
abnormally low levels of calcium in the blood
hypocalcemia
122
produce a diverse set of hormones, is retroperitoneal and they are surrounded by abundant adipose tissue
adrenal glands (suprarenal)
123
adrenal glands are composed of: (2)
medulla - arises from neural crest cells
cortex - derived from mesoderm
124
LAYERS OF ADRENAL CORTEX (3)
zona glomerulosa - secretes aldosterone (mineralocorticoid)
zona fasciculata - secretes cortisol (glucocorticoid)
zona reticularis - secretes androgens and estrogen (and glucocorticoid)
125
modified sympathetic nervous system
ganglion
adrenal medulla
126
ADRENAL MEDULLA HORMONES (2)
epinephrine (80%; increases blood glucose levels) & norepinephrine (20%) - increased cardiac output; increased blood flow to skeletal muscles and to the heart; vasoconstriction of blood vessels, especially in the viscera
and skin; increased release of glucose and fatty acids into the blood; in general, preparation for physical activity
127
ADRENAL CORTEX HORMONES (3)
mineralocorticoids - regulate ion balance in the blood and are the major secretory products of the zona glomerulosa of the adrenal cortex; produces aldosterone
glucocorticoids - help to provide energy for cells by stimulating the
increased use of lipids and proteins
androgens
128
secreted under low blood pressure conditions; secreted under low blood pressure conditions
aldosterone
129
the synthesis of new glucose from precursor molecules,
such as amino acids in the liver),
gluconeogenesis
130
generic term for steroid hormones that cause the development of male secondary sex characteristics
Androgen
131
both an exocrine gland and an endocrine gland
pancreas
132
exocrine portion of pancreas
acini produce pancreatic juice, and a duct system, which carries the
pancreatic juice to the small intestine
133
endocrine portion of pancreas
pancreatic islets (islets of Langerhans) secrete hormones that enter the plasma of the blood
134
secrete glucagon
alpha (α) cells (20%) - Increased breakdown of glycogen; release of glucose into the blood
135
secrete insulin (lowers blood glucose levels by
stimulating glucose transport into body cells)
beta (β) cells (75%) - Increased uptake and use of glucose and amino
acids
136
secrete somatostatin
delta (δ) cells - Inhibition of insulin and glucagon secretion
137
a collection of neurons in the hypothalamus that
controls appetite
satiety center
138
intense sensation of hunger in spite of high blood glucose levels
polyphagia
138
results primarily from
the inadequate secretion of insulin or
the inability of tissues to respond to
insulin.
Diabetes mellitus
139
also called insulin-dependent diabetes mellitus (IDDM),
results from diminished insulin secretion. It develops as a result of
autoimmune destruction of the pancreatic
islets, and symptoms appear after approximately 90% of the islets have been destroyed
Type 1 diabetes mellitus
140
also called noninsulin-dependent diabetes mellitus
(NIDDM), usually develops in people older than 40–45 years
of age
Type 2 diabetes mellitus (more common)
141
companion hormone to insulin
glucagon
142
elevated blood levels of glucose
hyperglycemia
143
low blood levels
of glucose
hypoglycemia
144
main endocrine
glands of the male reproductive system
testes
145
main hormone secreted by the
testes
testosterone
146
regulates the
production of sperm cells by the testes and the development and
maintenance of male reproductive organs and secondary sexual
characteristics.
testosterone
147
inhibits the secretion of FSH from the anterior
pituitary gland.
inhibin
148
main endocrine glands of the female reproductive system
ovaries
149
main hormones secreted by the ovaries
estrogen and progesterone
150
Inhibits FSH secretion
inhibin
150
Aids in uterine and mammary gland development and function, maturation of genitalia, secondary sex characteristics, sexual behavior (only estrogen), and menstrual cycle
estrogen and progesterone
150
Increases the flexibility of connective tissue in the pelvic area, especially the symphysis pubis
relaxin
151
act on the hypothalamus and the gonads to
inhibit reproductive functions, such as by inhibiting the secretion
of certain reproductive hormones
pineal gland
152
Two substances have been proposed as secretory products:
melatonin - decrease hypothalamic GnRH secretion, may
inhibit reproductive functions, and also help regulate sleep
cycles by increasing the tendency to sleep
arginine vasotocin -- regulate the function of the reproductive system in some animals; Possible inhibition of gonadotropin-releasing hormone secretion
153
In some animals, pineal secretions are regulated by the
____, the amount of daylight and darkness that occurs
each day and changes with the seasons of the year
photo period
154
important for immune function that is in
the neck and superior to the heart in the thorax
thymus
155
The thymus
secretes the hormone
thymosin (development and maturation of the immune system)
