Chapter 18: Lecture Midterm II Flashcards
(162 cards)
1
Q
What two systems act together to coordinate all systems of the body
A
endocrine and nervous system
2
Q
The nervous system releases —- whereas the endocrine system releases —-
A
neurotransmitters, hormones
3
Q
hormones and neurotransmitters bind to receptors on
A
target cells
4
Q
Which systems responses are slower than the other; nervous or endocrine
A
endocrine; some hormones act within seconds, others act within several minutes
5
Q
—- released locally in response to nerve impulses
A
neurotransmitters
6
Q
—- delivered to tissues throughout the body by blood
A
hormones
7
Q
target cells for neurotransmitters;
A
- muscle (smooth, cardiac, skeletal) fibers, gland cells and other neurons
8
Q
types of target cells for hormones
A
cells throughout the body
9
Q
exocrine glands
A
- secrete their products into ducts
- none of these are hormones
- includes; sudoriferous (sweat) glands, sebaceous glands, mucous glands, digestive glands
10
Q
endocrine glands
A
- do not have ducts, they secrete their hormones directly into the interstitial fluid that surrounds them
- secreting cells can be found in; hypothalamus, thymus, pancreas, ovaries, testes, stomach, liver, small intestine, skin, heart, adipose tissue, placenta
11
Q
examples of endocrine glands;
A
pituitary
thyroid
parathyroid
adrenal
pineal
12
Q
hormones travelling throughout the body will only affect target cells that
A
possess specific protein receptors for the hormone
13
Q
receptors may be down-regulated in the presence of
A
high concentrations of the hormone
14
Q
receptors may be up-regulated in the presence of
A
low concentrations of hormone
15
Q
circulating hormones
A
pass from secretory cells that make them into interstitial fluid and then blood
16
Q
local hormones
A
act locally on neighbouring cells or on the same cell that secreted them without entering the bloodstream
17
Q
local hormones that act on neighbouring cells are called
A
paracrines
18
Q
local hormones that act on the same cell that secreted them are called
A
autocrines
19
Q
what does nitric oxide do
A
relaxes smooth muscles which csuses vasodilation
20
Q
water soluble hormones circulate freely in plasma and bind to
A
receptors on the exterior surface of the target cell
21
Q
lipid-soluble hormones circulate bound to transport proteins
A
bind to receptors within target cells
22
Q
examples of steroid hormones (lipid soluble hormones)
A
- aldosterone
- calcitriol
- testosterone
- estrogens and progesterone
23
Q
examples of thyroid hormones (lipid soluble hormones)
A
T3 and T4
24
Q
examples of eicosanoids (gas) - water soluble hormones
A
- nitric oxide
- prostaglandins
- leukotrienes
25
examples of amines (water soluble hormones)
-epinephrine
- norepinephrine
- melatonin
- histamine
- serotonin
26
examples of peptides and proteins (water soluble hormones)
- all hypothalamic releasing and inhibiting hormones
- oxytocin
- ADH
- insulin
- glucagon
- cacitonin
- leptin
- erythropotein
27
how a target cell responds to a hormone is based on:
- hormones concentration in the blood
- the number of hormone receptors on the target cell
- influences exerted by other hormones
28
some hormones work more efficiently when a second hormone is present to assist them
synergist effect
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some hormones oppose the action of others
antagonist effect
example: testosterone and estrogen
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action of lipid soluble hormones
1. lipid-hormone molecule diffuses from blood, through interstitial fluid to the lipid bilayer of plasma membrane into the cell
2. if the cell is a target cell, the hormone binds to and activates receptors located within the cytosol or nucleus; then alters the gene expression
3. as he DNA is transcribed, it directs synthesis of a new protein
4. the new proteins alter the cells response and cause the responses typical of that hormone
31
not all lipid-soluble hormones bind to receptor cells. they may use a mechanism that is typical like water soluble hormones
eicosanoid
32
water soluble hormones bind to receptors that
protrude from the target cell surface
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because amine, peptide and protein hormones are no lipid-soluble, they cannot
diffuse through plasma membrane of cells and bind to receptors inside target cells
34
when a water soluble hormone binds to its receptor at the outer surface of the plasma membrame;
it acts as the first messenger
35
what does the first messenger cause (water soluble hormones)
causes a production of a second messenger inside the cell, where specific hormone-stimulated responses take place
36
one common messenger is known as
cyclic AMP (cAMP)
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action of water soluble hormones
1. a water soluble hormone (the first messenger) diffuses from the blood into interstitial fluid and then binds to it's receptor at the exterior surface of a target cells plasma membrane. Activates a G protein which activates adenylyl cyclase
2. Adenylyl cyclase converts ATP into cyclic AMP. Because the enzymes active site is on the inner surface, this reaction occurs in the cytosol of the cell
3. Cyclic AMP(second messenger) activates one or more protein kinases. converts ATP to ADP
4. activated protein kinases phosphorylate. This turns some proteins on and some off.
5. phosphorylated proteins cause reactions that produce physiological responses. therefore one protein might trigger glycogen synthesis whereas another may cause breakdown of trigycerides
6. Lastly the enzyme phosphodiesterase (inactivated cAMP) turns off the cells new hormone molecyles contunue to bind to the receptors
38
the release of most hormones occurs in
short bursts, with little or no secretion between bursts
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hormone secretion is regulated by
- signals from the nervous system
- chemical changes in the blood
- other hormones
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most hormone regulation is achieved via
negative feedback
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other hormones operate via
positive feedback such as oxytocin
42
the hypothalamus and the pituitary gland are connected via the
infundibulum
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the hypothalamus secretes
releasing and inhibiting hormones that control the release of hormones by the pituitary gland
44
The hormones from the hypothalamus reach the pituitary gland via the
hypophyseal portal system
45
How does the hypophyseal portal system work
- from the primary plexus, blood drains into the hypophyseal portal veins that pass down the outside of the infundibula stalk
- the veins divide again at the anterior pituitary called the secondary plexus of the hypophyseal portal system
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which hormone is the most plentiful in the anterior pituitary
human growth hormone
47
Growth hormone:
- target tissue
- principal actions
- liver and other tissues
- stimulates liver, muscle, cartilage, bone and other tissues to secrete insulin like growth factors that promote growth of body tissues
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Thyroid stimulating hormone:
- target tissue
- principal actions
- Thyroid gland
- stimulates synthesis and secretion of thyroid hormones by the thyroid gland
49
Follicle stimulating hormone:
- target tissue
- principal actions
- ovaries and testes
- females: initiates development of oocytes and induces ovarian secretion of estrogens
- males: stimulates testes to produce sperm
50
Luteinizing hormone:
- target tissue
- principal actions
- ovaries and testes
- females: stimulates secretion of estrogens and progesterone, brings about ovulation, formation of corpus luteum
- males: stimulates testes to produce testosterone
51
Prolactin:
- target tissue
- principal actions
- mammary glands
- together with other hormones, promotes milk production by mammary glands
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Adrenocorticotropic hormone:
- target tissue
- principal actions
- suprarenal cortex
- stimulates secretion of glucocorticoids (mainly cortisol) by the suprarenal cortex
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Melanocyte stimulating hormone:
- target tissue
- principal actions
- brain
- exact role is unknown, when present in excess, can cause darkening of the skin
54
Posterior pituitary gland
does not synthesize any hormones, but stores and releases them
- oxytocin
- ADH
55
oxytocin:
- target tissue
- principal actions
- uterus, mammary glands
- stimulates contraction of smooth muscle cells of uterus during childbirth; stimulates contraction of myoepithelial cells in mammary glands to cause milk ejection
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antidiuretic hormone:
- target tissue
- principal actions
- kidneys, arterioles, sudoriferous glands
- conserves body water by decreasing urine volume; decreases water loss through perspiration; raises blood pressure by constricting arterioles
57
Thyroid gland
a butterfly shaped gland located inferior to the larynx and anterior to the trachea
- has r and l lobes connected by isthmus
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follicular cells of the thyroid gland are stimulated by
TSH to produce T3 and T4 cells
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C-thyrocytes or parafollicular cells produce
calcitonin
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What are the 8 steps for synthesis and secretion of thyroid hormones
1. iodide trapping
2. synthesis of thyroglobulin
3. oxidation of iodide
4. iodination of tyrosine
5. coupling of T1 and T2
6. pinocytosis and digestion of colloid
7. secretion of thyroid hormones
8. transport to the blood
61
Iodide trapping (step 1 of thyroid process)
- thyroid follicular cells trap iodine ions by actively transporting them from blood into the cytosol
- as a result the thyroid gland contains most of the iodine in the body
62
Synthesis of thyroglobulin (TGB) - (step 2 of thyroid process)
- while the T thyrocytes are trapping iodine, they are also synthesizing TGB ( a glycoprotein in the ER); the vesicles undergo exocytosis and release the TGB into the lumen of the follicle
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Oxidation of iodide (step 3 of thyroid process)
negatively charged iodine ions must under go oxidation in order to be able to bind to tyrosine
- as they are oxidized, they pass through the membrane into the lumen of the follicle
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Iodination of tyrosine (step 4 of thyroid process)
as iodine molecules bind with tyrosine, it becomes monoiodotyrosine, a second iodination produces diodotyrosine; a sticky material that accumulates and is stored in the lumen of the thyroid follicle termed colloid
65
Coupling od T1 and T2 (step 5 of thyroid process)
during the last step of synthesis of thyroid hormone, two T2 molecules join to form T4, or one T1 and T2 join to form T3
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Pinocytosis and digestion of colloid (step 6 of thyroid process)
- droplets of colloid re-enter T thyrocytes by pinocytosis and merge with lysosomes.
- digestive enzymes in the lysosomes break down TGB cleaving off molecules of T3 and T4
67
Secretion of thyroid hormones (step 7 of thyroid process)
because T3 an T4 are lipid soluble, they diffuse through the plasma membrane into the interstitial fluid, and then into the blood.
- T4 is normally secreted in greater quantity than T3, but T3 is several times more potent
- moreover, once T4 enters a body cell, most of it is converted to T3 by removal of one iodine
68
Transport in the blood (step 8 of thyroid process)
more than 99% of both T3 and T4 combine with transport proteins in the blood mainly thyroxine-binding globulin
69
Function of thyroid hormones
- increase basal metabolic rate
- maintain normal body temp
- stimulate protein synthesis
- increase use of glucose and fatty acids for ATP production
- work with hGH and insulin to accelerate body growth
70
Parathyroid gland
located on the posterior aspect of each lobe on the thyroid gland
71
What two cells do the parathyroid glands contain
- chief cells: produce the parathyroid hormone PTH
- Oxyphil cells; function is unknown
72
Calcitonin produce by the thyroid gland works in junction wtih
PTH (parathyroid hormone) and calcitriol to regulate calcium homeostasis
73
Function of parathyroid hormone
increases blood calcium and magnesium levels and decreases phosphate levels; increases bone resorption by osteoclasts; increases calcium reabsorption and phosphate excretion by the kidneys; promotes formation of calcitriol (active form of vit d -which promotes dietary calcium and magnesium absorption)
74
Suprarenal glands (adrenal glands)
- lie superior to each kidney in the retroperitoneal space, have a flattened pyramid shape
- produce steroid hormones that are essential for life
- comprised of suprarenal cortex and medulla
75
The suprarenal cortex is divided into three zones (each secrete different hormones):
- zona glomerulosa (outer)
- zona fasciculata (middle)
- zona reticularis (inner)
76
The zona glomerolusa secretes hormones called
mineralcorticoids
77
The zona fasciculata secretes hormones called
glucocorticoids
78
The zona reticularis secretes hormones called
androgens ( steroid hormones that have masculinizing effects)
79
Aldosterone is a mineralcorticoid secreted by the
zona glomerolusa
80
Aldosterone
- regulates homeostasis of Na+ and K+
- helps adjust blood pressure and blood volume
81
the ----- controls secretion of aldosterone
The renin - angiotensin- aldosterone pathway (RAA)
82
The renin -angiotensin - aldosterone pathway
- dehydration, leads to decrease in bp and blood volume
- this is detected by juxtaglomerular cells in the kidneys
- the juxtaglomerular cells secrete renin which converts angiotensinogen to angiotensin I which eventually gets turned to angiotensin II
- angiotensin II causes vasoconstriction, and stimulates secretion of aldosterone by the suprarenal cortex
- aldosterone increases sodium and water absorption by the kidneys and increases secretion of K+ and H+ into urine
83
Cortisol is a glucocorticoid secreted by the
zona fasciculata
84
glucocorticoids are regulated by
negative feedback loop
85
Glucocorticoids helps control (FUNCTION)
- protein breakdown (increase the rate
- glucose formation
- lipolysis
- resistance to stress
- inflammation
- immune responses
86
low blood levels of glucocorticoids, mainly cortisol, stimulate neurosecretory cells in the hypothalamus to secrete
corticotripin-releasing hormone
87
The major androgen secreted by the suprarenal gland (by zona reticularis)
is the deydroepiandosterone (DHEA)
88
Function of androgens in males
- in males after puberty, the androgen testosterone is also released in much greater quantity by the testes
- therefore the amount of androgen secreted by suprarenal glands is insignificant
- stimulate growth of axillary and pubic hair
89
Function of androgens in females
- promote libido
- are converted to estrogens
- stimulate growth of axillary and pubic hair
90
After menopause when ovarian secretion of estrogen ceases,
all female estrogens come from the conversion of suprarenal androgens
91
The suprarenal medulla is a modified
sympathetic ganglion of the autonomic nervous system
92
The hormone producing cells in the suprarenal medulla are the
chromaffin cells (ANS exerts direct control over chromaffin cells)
93
The two major hormones released by the suprarenal medulla is
epinephrine and norepinephrine
94
the hormones of the suprarenal medulla intensify which responses
sympathetic responses
95
when do chromaffin cells get stimulated by the sympathetic preganglionic neurons
during stress or exercise
96
Function of epinephrine and norepinephrine:
- increase hr and force of contraction
- increase bp
- increase blood flow to; heart, liver, skeletal muscles, adipose tissue
- dilate airways to the lungs; increase blood levels of glucose and fatty acids
97
Pancreas
located in the curve of the duodenum
- it is both and exocrine and endocrine gland
98
Roughly 99% of the cells of the pancreas are ...
pancreatic acini (exocrine cells)
99
What do the pancreatic acini produce
- digestive enzymes which flow into the digestive canal through a network of ducts
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Pancreatic islets
scattered among acini
- endocrine cells
101
What are the four types of pancreatic islet cells
alpha: glucagon
beta: insulin
delta: somatostatin
pancreatic polypeptide cells: secrete pancreatic polypeptide
102
Function of glucagon:
- raises blood glucose level by accelerating breakdown of glycogen into glucose in the liver; converting other nutrients into glucose in the liver; releasing glucose into blood
103
Function of insulin
lowers blood glucose levels by accelerating transport of glucose into cells, converting glucose into glycogen. and decreasing glycogenolysis; increases lipogenesis and stimulates protein synthesis
104
Function of somatostatin
inhibits secretion of insulin and glucagon; slows absorption of nutrients from digestive canal
105
Function of pancreatic polypeptide
inhibits somatostatin secretion, gallbladder contraction, and secretion of pancreatic digestive enzymes
106
Gonads:
- organs that produce gametes; sperm in males and oocytes in females
- they also secrete hormones
107
Ovaries:
- paired oval bodies located in the female pelvic cavity
- produce several steroid hormones including; estrogens and progesterone
- produce inhibin, and relaxin
108
testes
- oval glands that lie in the scrotum
- produces testosterone (androgen)
109
Function of estrogen and progesterone
together with gonadotropic hormones from the anterior pituitary; regulate female reproductive cycle, maintain pregnancy, prepare mammary glands for lactation, and promote development and maintenance of female secondary sex characteristics
110
Function of relaxin
increases flexibility of pubic symphysis during pregnancy; helps dilate uterine cervix during labor and delivery
111
Inhibin
inhibits secretion of FSH from the anterior pituirary
112
Function of testosterone
stimulates decent of testes before birth, regulates sperm production; promotes development and maintenance of male secondary sex characteristics
113
Pineal gland
pinecone shaped small endocrine gland attached to the roof of the third ventricle in the brain at the midline
- consists of masses of neuroglia and secretory cells called pinealocytes
114
What does the pineal gland secrete
melatonin, an amine hormone derived from serotonin
115
Function of melanin
- contributes to body's biological clock
116
as more melatnonin is liberated during darkness than in light, this hormone is thought to promote
sleepiness
117
melatonin contributes to the setting of the body's biological clock, which is controlled by the
suprachiasmatic nucleus of the hypothalamus
118
Thymus
located behind the sternum between the lungs
119
The thymus produces
- thymosin, thymic humoral factor, thymic factor and thymopoietin
120
Function of hormones produced by the thymus
promote maturation of the immune systems T cells (type of wbc that destroys microbes and foreign substances) and may retard the aging process
121
What are other tissues that produce hormones but are not classified as endocrine glands
- eicosanoids
- growth factors
122
What are the two eicosanoid molecules
prostaglandins and leukotrienes
123
where are prostaglandins and leukotrienes found
in all body cells except RBCs, where they act as local hormones (paracrines or autocrines) in response to chemical or mechanical stimuli
124
Eicosanoids are locally acting hormones derived rom
20 carbon fatty aid arachidonic acid
125
To exert their effects, eicosanoids bind to receptors on
target cell plasma membranes and stimulate or inhibit the synthesis of second messengers such as cyclic AMP
126
Leukotrienes stimulate
chemotaxis (attraction to a chemical stimulus) of white blood cells and mediate inflammation
127
Prostaglandins function
- alter smooth muscle contraction, glandular secretions, blood flow, reproductive processes, platelet function, respiration, nerve impulse transmission, lipid metabolism , and immune responses
- they also have roles in promoting inflammation and fever and in intensifying pain
128
Skin: cholecalciferol
(hormones produced by other organs and tissues)
- plays a role in the synthesis of calcitriol, the active form of vitamin D
129
Digestive canal: gastrin
(hormones produced by other organs and tissues)
promotes secretion of gastric juice; increases movements of the stomach
130
Digestive canal: glucose-dependent insulinotropic peptide (GIP)
stimulates release of insulin by pancreatic beta cells
131
Digestive canal: Secretin
(hormones produced by other organs and tissues)
stimulates secretion of pancreatic juice and bile
132
Digestive canal: cholecystokinin
(hormones produced by other organs and tissues)
stimulates secretion of pancreatic juice and bile; regulates release of bile from gallbladder; causes feeling of fullness after eating
133
Placenta: Human chorionic gonadotropin
(hormones produced by other organs and tissues)
stimulates corpus luteum in ovary to continue production of estrogens and progesterone to mantain pregnancy
134
Placenta: estrogens and progesterone
(hormones produced by other organs and tissues)
maintain pregnancy; help prepare mammary glands to secrete milk
135
Placenta: Human chorionic gonadotropin
(hormones produced by other organs and tissues)
stimulates development of mammary glands for lactation
136
Kidneys: Renin
(hormones produced by other organs and tissues)
raises blood pressure by bringing about vasoconstriction and stimulates release of aldosterone
137
Kidneys: erythropoietin
(hormones produced by other organs and tissues)
increases rbc formation
138
Kidneys: calcitriol ( active form of vit d)
(hormones produced by other organs and tissues)
aids in absorption of dietary calcium and magnesium and phosphorus
139
Heart: Atrial natruiretic peptide (ANP)
(hormones produced by other organs and tissues)
decreases blood pressure
140
Adipose tissue: Leptin
(hormones produced by other organs and tissues)
suppresses appetite; may increase FSH and LH activity
141
Several newly discovered hormones are called
growth factors and they are involved in tissue development, growth, and repair
142
Epidermal growth factor:
- produced in submaxillary (salivary) glands; stimulates proliferation of epithelial cells, fibroblasts, neurons and astrocytes; suppresses some cancer cells and secretion of gastric juice by stomach
143
Platelet-derived growth factor
- produced in blood platelets;
- used for hair restoration in men
144
Fibroblast growth factor:
- found in pituitary gland and brain; stimulates proliferation of many cells derived from embryonic mesoderm
- stimulates formation of new blood vessels
145
Nerve growth factor
- produced in submandibular (salivary) glands
- stimulates growth of ganglia in embryo
- stimulates hypertrophy and differentiation of neurons
146
Tumor angiogenesis factors:
produced by normal and tumor cells; stimulates growth of new capillaries, organ regeneration, and wound healing
- forms blood vessels to tumor cells so they get O2 supply
147
Transforming growth factors;
produced by various separate molecyles
148
Eustress
prepares us to meet certain challenges and thus is helpful
149
Distress
any type of harmful stress that may be damaging
150
Stressor
any stimulus that produces a stress response
- examples; heat. cold, heavy bleeding from wound, strong emotional reaction
151
Three stages to a stress response
1. initial fight or flight
2. slower resistance reaction
3. exhaustion
152
The fight or flight response is initiated by nerve impulses sent from the ----- to the ----
hypothalamus to the sympathetic part of the autonomic nervous system
153
the fight or flight stimulates the body's
resources to prepare for immediate activity
154
The resistance stage
lasts longer than the fight or flight stage
155
The resistance stage helps the body to continue
fighting a stressor long after fight or flight response disappears
- this is why our heart pounds for several minutes after the stressor is removed
156
Exhaustion
resources of the body may eventually become so depleted that they cannot sustain the resistance stage
157
Prolonged exposure to high levels of
cortisol and other hormones in the resistance reaction cause supression of the immune system, ulceration of digestive canal, and failure of pancreatic beta cells
158
Pituitary gigantism/acromegaly
caused by excess secretion of growth hormone
- abnormal increase in length of bones
159
Goiter
caused by a reduction in the production of thyroid hormone
160
Graves disease
develops due to excess thyroid hormone
161
Cushings syndrome
characterized by hypersecretion of the suprarenal cortx
- bufallo hump
- flushed skin
- easy bruises
- poor wound healing
162
elevated levels of cortisol in cushings syndrome causes
hyperglycemia, osteoporosis, weakness, hypertension and increased susceptibility to infection
