Endocrinology Flashcards
1
Q
Hormones
A
cell to cell communication molecules
2
Q
Pheremones
A
organism to organism communication
3
Q
Hormones control
A
rates of enzymatic reactions, transport of ions/molecules across cell membranes, gene expression, protein synthesis
4
Q
Hormones exert effects at _____ concentrations
A
very low
5
Q
Hormone length of activity is dependent on
A
Half-life
6
Q
Classifications of hormones
A
Peptide/protein, steroid, amine
7
Q
Preprohormone
A
Large, inactive peptide hormones
8
Q
Prohormones
A
Modified preprohormones, precursor to peptide hormones; smaller, still inactive
9
Q
Peptide hormone synthesis
A
Preprohormone –> prohormone –> peptide hormone
10
Q
Peptide hormone storage
A
Stored in secretory vesicles
11
Q
Post-translational modification of prohormones
A
transformation into active peptide hormones; cleavage by enzymes in golgi body
12
Q
Mechanism of action by peptide hormones
A
Hormone binds to surface receptors, signal transduction, enzymes activated, channels open, second messenger system activated, cellular response
13
Q
Peptide hormones bind to surface receptors and initiate a second messenger system because…
A
They cannot pass through lipid bilayer
14
Q
Steroid hormones are derived from
A
Cholesterol
15
Q
Why can steroid hormones enter the cell?
A
Lipophilic, can pass through membrane
16
Q
Target for steroid hormones
A
Cytoplasmic or nuclear receptors
17
Q
Action of steroid hormones
A
Activate DNA for protein synthesis
18
Q
Examples of steroid hormones
A
Cortisol, estrogen, testosterone
19
Q
Examples of peptide hormones
A
Insulin, oxytocin, parathyroid hormone
20
Q
Half-life of steroid hormones
A
Long
21
Q
Speed of action of steroid hormones
A
Slow
22
Q
Half-life of peptide hormones
A
Short
23
Q
Why can’t steroid hormones be stored in vesicles?
A
They are lipophilic and cannot be contained
24
Q
Because steroids cannot be stored in vesicles, they are produced….
A
as needed
25
Steroid-producing organs
adrenal cortex (adrenal glands), gonads and placenta
26
Steroid-producing organelle
Smooth ER
27
Why must steroids be bound to protein carrier molecules in the blood?
They are not very soluble in plasma and other body fluids
28
Mechanism of action by steroid hormones
Unbound steroid hormone diffuses into target cell, reaches receptor (nucleus or cytoplasm), receptor-hormone complex binds to DNA and represses/activates gene(s), activated genes are expressed (generate new proteins)
29
Amine hormones are derived from
Tyrosine, tryptophan
30
Examples of amine hormones
Thyroid hormones, catecholamines (epinephrine, norepinephrine, dopamine)
31
Catecholamines
Epinephrine, norepinephrine, dopamine; neurohormone, bind to cell membrane receptors
32
Thyroid hormones
T3, T4; behave similar to steroid hormones
33
Difference between catecholamines and thyroid hormones (both are amine hormones)
Behavior; catecholamines behave like peptide hormones, thyroid hormones behave like steroid hormones
34
Endocrine reflex pathway
Stimulus, afferent signal, integration, efferent signal (the hormone), physiological action, negative feedback
35
4 mechanisms of control for hormone secretion
regulation by nervous system, regulation by chemical change in blood, regulation by organ stretching, regulation by another hormone
36
Hormone regulation by nervous system
Nervous system --> adrenal medulla --> catecholamines
37
Hormone regulation by chemical change in blood
Low level of an ion --> gland detection --> release of gland hormone --> increase in ion concentration
38
Hormone regulation by organ stretching (ex. cervix)
Stretching of cervix --> posterior pituitary activated --> oxytocin released --> uterus contracts (POSITIVE FEEDBACK)
39
Hormone regulation by secretion of another hormone
Gland releases hormone --> targets another gland --> second gland releases effector hormone
40
Posterior pituitary hormones
Vasopressin, oxytocin
41
Anterior pituitary hormones
GH, TSH, ACTH, PRL, FSH, LH
42
GH
Growth hormone (somatoroph)
43
TSH
Thyroid-stimulating hormone (thyrotroph)
44
ACTH
Adrenocorticotropic hormone (corticotroph)
45
PRL
Prolactin (lactotroph)
46
FSH
Follicle stimulating hormone (gonadotroph)
47
LH
Luteinizing hormone (gonadotroph)
48
Control of release of AP hormones
Hypothalamus
49
Hypothalamus hormones
Releasing hormones: GHRH, TRH, CRH, PRH, GnRH; Inhibiting hormones: GHIH, PIH
50
PIH
Prolactin inhibiting hormone, released by hypothalamus
51
GHIH
Growth hormone inhibiting hormone, released by hypothalamus
52
AP vs. PP
AP is true endocrine tissue, PP is extension of neural tissue; AP releases more hormones
53
SEQ Hypothalamic-Hypophyseal Portal System
Neurons synthesizing trophic neurohormones release neurohormones into capillaries of portal system; portal veins carry trophic hormones to AP; hormones act on AP; endocrine cells of AP release hormones into second set of capillaries for distribution into body
54
Hypothalamic-Hypophyseal Portal System
Connection between hypothalamus and anterior pituitary; carries neurohormones to AP and hormones from AP to rest of body
55
Three levels of endocrine control
Hypothalamic stimulation, pituitary stimulation, endocrine gland stimulation
56
Three hormone-hormone interactions
Permissive, synergistic, antagonistic
57
Permissive hormone-hormone interaction
Increases the effect of one hormone
58
Synergistic hormone-hormone interaction
Increases the effect of both hormones
59
Antagonistic hormone-hormone interaction
One hormone decreases the effect of another hormone
60
Thyroid gland cell types
Follicular cells, parafollicular cells
61
Thyroid follicular cells
Produce T4 and T3
62
Thyroid parafollicular cells
Produce calcitonin
63
Function of T3 and T4
Bind to receptors in somatic cells and initiate gene transcription, protein synthesis; increase basal metabolic rate, enhance action of catecholamines, regulate development and growth of nervous tissue and bones
64
Long term effects of thyroid hormones
Metabolism, normal growth and development, nervous system development
65
Hyperthyroidism
Overactive thyroid; increases metabolism (heat, oxygen consumption), muscle weakness (protein catabolism increased), high heart rate (increases activity of epinepherine/norepinepherine)
66
Sign of hyperthyroidism
Goiter
67
Hypothyroidism
Decreased thyroid activity; slowed metabolism, oxygen consumption, heart rate, slowed reflexes, speech, thoughts, feelings of fatigue, decreased protein synthesis
68
Parathyroid glands
Small, embedded within thyroid gland; release parathyroid hormone
69
Function of PTH
major regulator of extracellular Ca2+, Mg2+, and HPO42- concentrations
70
Role of calcium in the body
Intracellular signaling, structural functions (strength of bone matrix, tight junctions), blood coagulation cofactors, neuron/muscle excitability
71
What comprises the majority of total body calcium?
Calcium in bone matrix (99%)
72
Osteoblasts
Deposit calcium as bone matrix is produced
73
Osteoclasts
Break down bone matrix during bone resorption; secrete acid and enzymes
74
Calcitrol
Released when Ca2+ low, increases intestinal calcium absorption, ensures Ca2+ available in extracellular fluid
75
Calcitonin
Released when Ca2+ high, stops release from bone, increases excretion
76
Adrenal glands
Located on top of kidneys, inner medulla and outer cortex
77
Adrenal gland medulla
Produces catecholamine hormones
78
Adrenal gland outer cortex
Produces steroid hormones; releases cortisol
79
Chromaffin cells
Cells of adrenal medulla that secrete norepinephrine and epinephrine
80
Functions of cortisol
Coping with long term stress (protects against hypoglycemia by stimulating catabolism of energy stores), promote gluconeogenesis, breaks down skeletal muscle proteins, enhances lipolysis, suppresses immune system, causes negative calcium balance, influences brain function
81
Cortisol naturally fluctuates with
Circadian rhythm.
82
What secretes melatonin?
Pineal gland
83
Melatonin
Amine hormone derived from serotonin
84
Function of melatonin
Influence circadian rhythm, protects against free radicals, inhibits reproductive functions
85
Melatonin production inhibited by
Daytime
86
What secretes glucagon?
Alpha pancreatic islet cells
87
What secretes insulin?
Beta pancreatic islet cells
88
What secretes somatostatin?
Delta pancreatic islet cells
89
What secretes pancreatic polypeptide?
F pancreatic islet cells
90
Types of pancreatic islet cells
Alpha, beta, delta, F
91
Majority of pancreatic islet cells are ____ and produce ____
Beta, insulin
92
Function of insulin
Remove glucose from bloodstream (cellular uptake), cellular uptake of amino acids/fatty acids, formation of glycogen, proteins, triglycerides, inhibit release of glucose
93
Glucagon function
Breakdown glycogen, formation of glucose (gluconeogenesis), breakdown lipids, inhibit protein synthesis
