Cell Signaling and Endocrine System Flashcards
(147 cards)
1
Q
What are the 5 types of chemical messengers?
A
Amino acid messengers
Amine messengers
Peptide/Protein messengers
steroid messengers
Eicosanoid messengers
2
Q
what is the amino acid messengers function?
A
functions as a neurotransmitter of the central nervous system
3
Q
where are amino acids synthesized?
A
synthesized in the neuron mostly
4
Q
amino acid messengers are lipophobic and stores in __________ until released?
A
vesicles
5
Q
what are amine messengers derived from?
A
Derived from all amino acids
6
Q
what are amine messengers function?
A
can function as neurotransmitter, paracrine and hormones
7
Q
amine messengers are catecholamines. what are three examples of catecholamines?
A
dopamine, norepinephrine and epinephrine
8
Q
amine messengers are synthesized enzymatically in _________.
A
cytosol
9
Q
serotonin is derived from?
A
tryptophan, precursor for melatonin
10
Q
melatonin
A
hormone secreted by the pineal gland and is important for regulating circadian rhythm
11
Q
what is histamine derived from? what is it involved in?
A
histidine and involved in inflammatory reactions
12
Q
what are peptide/ protein messenger characteristics?
A
- fewer than 50 amino acids long
- proteins are long polypeptide chains
- lipophobic, stored in vesicles until released
13
Q
in post translational modification prepropeptides are formed in the ?
A
lumen of rough endoplasmic reticulum
14
Q
post translational modification is cleaved by?
A
proteolytic enzymes forming propeptide
15
Q
in post translational modification where is propeptide sent to?
A
sent to the Golgi via smooth endoplasmic reticulum
16
Q
what are the steps of post translational modification?
A
- prepropeptide is formed in the lumen of the rough ER
- then is cleaved by proteolytic enzymes froming propeptide
- then propeptide is sent to the golgi via smooth ER
- propeptide cleaves to peptide on golgi, secondary vesicles released
17
Q
what are steroid messengers derived from?
A
cholesterol (lipophilic)
18
Q
in steroid messengers, enzymes catalyze cholesterol in the?
A
smooth ER and mitochondria
19
Q
T/F: steroid messengers must be synthesized on demand and released immediately
A
true
20
Q
what are eicosanoid messengers derived from?
A
arachidonic acid (lipophilic)
21
Q
in eicosanoid messgers, phospholipase A2 cleaves _______ _________ from membrane phospholipid.
A
arachidonic acid
22
Q
what two pathways are eicosandoids produced by?
A
cyclooxygenase and lipoxygenase
23
Q
autocines, paracrines, neurotransmitters are trnasported to _____ ____ via ______ _______ and quicly degrade.
A
target cells, simple diffusion
24
Q
how are hormones transported?
A
via circulatory system in dissolved form or via carrier proteins
25
what is the process of signal transduction?
- chemical messengers bind to target cell receptors
- then the messenger/ receptor binding changes the activity of the cell
- receptor binds to only 1 messenger
26
affinity
the strength of binding between messenger and receptor
27
in singnal transduction, can messengers bind to more than one receptor?
yes
28
in signal transduction do target cells have multiple types of receptors?
yes
29
what do target cell response to a chemical messenger depend on?
- messenger concentration
- number of receptors
- affinity
- antagonistic messengers
30
up regulation
increased production of receptors
31
down regulation
decreased production of receptors
32
explain the process of intracellular receptors
- lipophilic hormones pass through membrane and bind to receptor in cytoplasm
- hormone receptor complex binds to hormone response element
- binging activates or deactivates gene
33
what are the three membrane bound receptors?
channel linked receptors
enzyme linked receptors
G protein linked receptors
34
what is the process of membrane bound receptors?
- lipophocic messenger cannot pass through plasma membrane
- so it binds to receptors situated within the plasma membrane
35
what are examples of channel linked receptors?
fast ligand gated ion channel
calcium channel
36
explain the function of channel linked receptors?
- functions as a second messenger by binding to calmodulin
- then calcium calmodulin complex activates protein kinase which alters cellular functioning
37
what is the function of enzyme linked receptors?
- functions as both as a receptor and an enzyme
- changes protein activity producing a response
38
how does the enzyme linked receptors for tyrosine kinase work?
messenger binds to receptor changing conformation which activates tyrosine kinase to catalyze the phosphorylation of intracellular protein
39
explain the process of G protein linked receptors work?
- bound receptor activates g proteins
- g protein functions as a link between receptor and other membrane proteins
- alpha subunit binds with GDP during inactive state
- messenger binds with receptor which causes g protein to release GDP and bind with GTP and become activated
- alpha subunit is released
- alpha subunit binds to ion channel changing conformation which opens/ closes the channel
40
explain cAMP second messenger system
- first messenger binds to receptor and actiates Gs protein
- alpha subunit binds and activates adelylate cyclase which catalyzes conversion of ATP to cAMP
-cAMP activates protein kinase A which transfers phosphate from ATP to protein causing signal transduction
- termination of cAMP requires cAMP phosphodiesterase
- phosphoprotein phosphatase removes phosphate from protein
41
explain phosphatidylinositol second messenger system
- messenger binds to receptor activating Gs protein, releasing alpha subunit which binds to and activates phospholipase C
- phospholipase C catalyzes conversion of PIP2 to DAG and IP3
- DAG activates protein kinase C which catalyzes conversion phosphorylation of proteins
- IP3 triggers release of calcium from endoplasmic reticulum
- calcium combines with calmodulin activating protein kinase
42
explain the process of signal amplification
- one messenger binds to one receptor
- several G proteins are activated
- each G protein activates an adenylic cyclase
- each adenylic cyclase generates hundreds of cAMP molecules
- each cAMP activates protein kinase A
- each protein kinase A phosphorylates hundreds of proteins
43
what are the two important control systems to maintain homeostasis?
autonomic nervous system and endocrine system
44
autonomic nervous system
communicates via nerve impulses resulting in rapid short lived responses
45
endocrine system
communicates via hormones resulting in slower prolonged responses
46
what are three components of the endocrine system?
- endocrine cells and glands/organs
- hormones transported by circulatory system
- specific target cells that posses receptors that respond to specific hormone
47
what is the function of the endocrine system?
- reproduction
- metabolism
- osmoregulation
- growth and development
- digestion
- sleep/mood
48
what are two types of endocrine organs?
primary and secondary
49
primary endocrine organs function?
secrete hormones
50
secondary endocrine organ function?
secretion is secondary to some other function
51
what are examples of primary endocrine organs?
hypothalamus, pituitary gland, thyroid, pancreas, gonads
52
what are examples of secondary endocrine organs?
heart, liver, skin, stomach, small intestine, kidney
53
hypothalamus
forebrain region that coordinates both ANS and activity of pituitary gland
54
what does the hypothalamus control?
body temp, thirst, hunger, sleep, emotional activity
55
pituita (phlegm)
protrusion off hypothalamus, divided into anterior lobe and posterior pituitary lobe
56
what are two embryonic sources?
neurohypophyseal bud and rathkes pouch
57
neurohypophyseal bud
ventral outgrowth from forebrain derived from neuroectoderm, becomes posterior pituitary lobe
58
another name for posterior pituitary lobe?
neurohypophysis
59
Rathkes pouch
dorsal outgrowth of roof of mouth, derived from oral ectoderm, becomes anterior pituitary lobe
60
another name for anterior pituitary lobe?
adenohypophysis
61
what kind of tissue is the posterior pituitary lobe made of?
nervous tissue
62
Describe how the posterior pituitary lobe works
-contains axon terminal ends of hypothalamic neurons
- secretes 2 neurohormones into capilaary bed and then into general circulation
- neurosecretory cell bodies within supraoptic nucleus of hypothalamus synthesize oxytocin
- neurosecretory cell bodies within paraventricular nucleus of hypothalamus sythesize ADH
63
what does oxytocin do?
-stimulates contraction of smooth muscles of uterus during labor
- stimulates contraction of myoepithelial cells which release breast milk produced by milk secreting epithelial cells (milk letdown)
- social interactions (pair bonding, strong affinity to mate)
64
what does antidiuretic hormone (ADH) regulate?
water conservation
65
explain the process of ADH
-sensors in hypothalamus detect and increase in blood osmolarity or decrease in blood volume during times of dehydration
- then a release of ADH causes collecting ducts of nephron to be highly permeable to water which is then returned to the vasculature and increases blood volume and pressure
- solute concentrations become more dilute and ADH release is inhibited
66
how does alcohol inhibit ADH secretion?
causes dehydration and hangover associated with alcohol consumption
67
what are symptoms of diabetes insipidus?
hypo secretion of ADH, output of copious amounts of urine and intense thirst
68
when you drink alcohol, why do you pee alot?
Alcohol is a diuretic, which means it promotes increased urine production. When you drink alcohol, it inhibits the release of antidiuretic hormone, which is responsible for regulating the amount of water reabsorbed by the kidneys. Without enough antidiuretic hormone your kidneys reabsorb less water, leading to increased urine production and more frequent urination.
69
what kind of tissue is the anterior pituitary gland made of?
epithelial tissue
70
explain how the anterior pituitary lobe works
- tropin neurohormones are relased by neurosecretory neurons in the hypothalamus
- adenohypophyseal endocrine cells secrete hormone into general circulation
- tropin neurohormones may be releasing or inhibiting
71
explain the hypothalamic pituitary portal system works
- connects hypothalamus with anterior pituitary lobe
- hypothalamus secretes releasing or inhibiting tropin neurohormones into primary capillary bed
- tropin neurotransmitters travel to anterior lobe via portal vein and enter the second capillary bed
- tropin neurohormones leaves second capillary bed and stimulates release of hormones by adenohypophyseal endocrine cells
- if stimulated, adenohypophyseal endocrine cells release hormones into general circulation
72
secretion of tropin neurohormones is regulated by?
hypothalamic neural input
73
what is prolactin releasing hormone secreted by?
secreted from hypothalamus neurosecetory cells
74
what is the function of prolactin releasing hormone?
stimulates lactotrophs within anterior lobe to release prolactin
75
what is the prolactin inhibiting hormone secreted by?
secreted by hypothalamus neurosecretory cells
76
what is the function of theprolactin inhibiting hormone?
suppresses release of prolactin by lactotrophs
77
when do prolactin concentrations increase?
during pregnancy causing mammy gland enlargement
78
what is sustained PH release stimulated by?
infant suckling
79
what is the growth hormone releasing hormone secreted by?
hypothalamus neurosecetory cells
80
what is the function of the growth hormone releasing hormone?
stimulates somatotrophs within the anterior lobe to release growth hormone
81
what does growth hormone do in the liver?
stimulates the production of insulin like growth factors
82
what does insulin like growth factors in concert with growth hormone do?
stimulates growth, cell reproduction and regeneration (muscle and bone cell)
83
what is the growth hormone inhibiting hormone secreted by?
secreted by the hypothalamus nuerosecretory cells
84
what is the function of the growth hormone inhibiting hormone?
inhibits release of growth hormones by somatotrophs
85
T/F: growth hormone secretion has a circadian cycle that is highest during sleep and decreases with age
true
86
interstitial growth
increased length
87
appositional growth
increased thickness
88
epiphyseal plate
main site of longitudinal growth of the long bones
89
what effects do growth hormones have in children?
- increases calcium retention
- increases muscles mass through sarcomere hypertrophy
-promotes lipolysis
- stimulates growth of all external organs (excluding brain)
- reduced uptake and retention of glucose by liver
- contributes to the maintenance and function o pancreatic islets
- stimulates the immune system
- increases deiodination of t4 to t3 (thyroid hormones)
90
what is the result of hyper secretion of growth hormone in children?
gigantism, abnormally but proportionally tall (epiphyseal plates are still active)
91
what is the result of hyper secretion of growth hormone in adults?
acromegaly, overgrowth of bones in the face, feet and hands (long bones cannot grow because plates are closed), appositional growth of bone only
92
what is the result of hyposecretion of growth hormone in children? in adults?
-pituitary dwarfism, abnormally but proportionally short (can be treated to some degree)
-in adults there is no problem regarding growth
93
Achondroplasia
connective tissue disorder
94
what is thyrotropin releasing hormone secreted by?
secreted by the hypothalamus neurosecertory cells
95
what is the function of thyrotropin releasing hormone?
stimulates thyrotrophs within the anterior lobe to released thyroid stimulating hormone
96
what does thyroid stimulating hormone do?
stimulates the thyroid gland to secrete thyroid hormones (T3 AND T4)
97
what do thyroid hormones do?
increases metabolism, promotes growth and development
98
what happens if thyroid hormone blood levels increase?
suppresses the release of thyroid regulating hormone by hypothalamus neurosecretory cells and thyroid stimulating hormones by thyrotrophs
99
what is corticotropin releasing hormine secreted by?
hypothalamus neurosecretory cells
100
what is the function of corticotropin releasing hormone?
stimulates corticotrophs within the anterior lobe to release adrenocorticotropic hormone
101
what does the adrenocorticotropic hormone do?
stimulates adrenal cortex to release glucocorticoid hormones (ex. cortisol)
102
when is cortisol released?
in response to stress
103
what happens when cortisol levels rise?
suppresses corticotropin releasing hormone and adrenocorticotropic hormone release
104
what is gonadotropin releasing hormone secreted by?
hypothalamus neurosecretory cells
105
what is the function of gonadotropin releasing hormone?
stimulates gonadotrophs within the naterior lobe to release follicle stimulating hormone and luteinizing hormone
106
what does follicle stimulating hormone do?
promotes egg and sperm development and stimulates the ovary to secrete sex hormone estrogen and the testes to secrete testoserone
107
what does luteinizing hormone do?
stimulates ovulation and secretion of sex hormone estrogen and progesterone in females and androgens in males
108
what happens when estrogen and androgen levels rise?
suppresses gonadotropin releasing hormone release
109
what is the difference between short and long negative feedback loops?
short negative feedback loops involve direct inhibition of hormone secretion by the product of the process it regulates and occur relatively quickly, while long negative feedback loops involve multiple steps and regulatory factors, occurring over a longer time frame.
110
pineal gland
endocrine tissue that secretes neurohomone melatonin
111
why is melatonin important?
manages your circadian rhythm, levels raise at night, and used as a sleep agent
112
where is the thymus gland located?
anterior superior mediastinum (in front of the heart and behind the sternum)
113
what does the thymus gland do?
secretes thymosin
114
what does thymosin do?
promotes the maturation of T lymphocytes
115
when is the thymus gland largest and most active?
during neonatal and pre adolescent periods
116
when does the thymus gland begin to atrophy?
early teens years (replaced by adipose tissue in adults)
117
where is the thyroid gland located?
lies below the thyroid cartilage of the larynx and is surrounded by a connective capsule
118
what extends from the capsule to divide the thyroid into irregular lobes?
trabeculae
119
what hormones are produced by the thyroid?
T3- triiodothyronine
T4- tetraiodothyronine (thyroxine)
120
what is the functional unit of the thyroid gland?
follicle
121
describe the structure of the follicle
- single layer of simple cuboidal follicular cells surrounding a lumen.
- lumen filled with colloid produced and secreted by follicular cells
122
what does colloid consist of?
mainly of thyroglobulin (thyroid gland, precursor and storage form of thyroid hormone)
123
T/F: thyroid gland is synthesized in RER and enters colloid in via exocytosis
True
124
what are located between follicles in the thyroid gland?
calcitonin producing cells (C cells)
125
what does calcitonin do?
lovers blood calcium levels
126
In the thyroid gland, iodine is actively transported from blood into follicular cell via?
Then sent passively into colloid via?
Na+/I- symporter, pendrin transporter
127
explain the synthesis of thyroid hormones
- tyrosine residues of thyroid gland are iodinated
- 1 iodine forms MIT, 2 iodide ions form DIT
- 2 iodinated tyrosines (MIT or DIT) on the same thyroid gland covalently bond
- 2 DITs combine and form T4, 1 MIT and 1 DIT form to make T3.
- they are attached to the thyroid gland and stored
128
explain the secretion of thyroid hormones
- Thyroid secreting hormone binds to follicular cell membrane-bound receptors which activates cAMP secondary messenger system
- phosphorylated proteins causes endocytosis of iodinated thyroid gland from colloid via phagocytosis
- once inside cell, vesicle fuses with lysosome
- various proteases cleave thyroid gland to produce free T3 and T4
- T3 and T4 pass through membranes and bind with carrier proteins in blood
129
deficiency of iodine lead to decreatsed production of T3 and T4, this enlarges the tissue and will cause?
goitre
130
what is caused by the hyper secretion of thyroid hormones?
hyperthyroidism (graves disease)
131
What are symptoms of graves disease?
-elevated metabolic rate, sweating, raid/ irregular heart rate, nervousness, weightloss, oily skin and bulged eyes
132
how is graves disease corrected?
thyroid gland removal or ingestion of radioactive iodine to destroy most active thyroid cells
133
what is the result of underproduction of thyroid hormones?
hypothyroidism
134
hyperthyroidism can cause congenital thyroid abnormalities and autoimmune disorders such as?
hashimotos thyroiditis
135
what are symptoms of hypothyroidism?
abnormal weight gain, tiredness hairloss, dry skin, bradycardia
136
cretinism
severly stunted physical and mental growth due to untreated congential deficinecy of thyroid hormones
137
how is hypothyroidism treated?
hormone replacement therapy
138
where is the parathyroid glands located?
located on the surface of the thyroid gland
139
what is the function of parathyroid glands?
secretes parathyroid hormone (helps regulate Ca2+ levles by increasing blood Ca2+ levels)
140
hypocalcemia
low blood Ca2+ levels
141
hypercalcemia
high blood Ca2+ levels
142
adrenal glands location?
located above the kidneys
143
what are the three layers of the adrenal cortex?
zona glomerulosa
fasciculata
reticularis
144
mineralocorticoids, function?
cells of the zona glomerulosa. regulate Na+ reabsorption and K secretion from kidneys
145
sex hormones from the adrenal cortex. function?
cells of the zona fasciculata and reticularis. stimulates sex drive in femials
146
glucocorticoids, function?
cells of the zona fasciculata and reticularis. regulates response to stress
147
adrenal medulla
