Endocrine - Intro Flashcards
1
Q
Define
Hormones
A
Chemical signals (ligands) used for cell-to-cell communication by binding to receptors on/in target cells
Secretion of hormones is regulated
2
Q
Classic Endocrine Glands
List the 7 main glands
A
- Hypothalamus
- Pituitary Gland (Anterior/Posterior)
- Thyriod Gland
- Parathyroid Gland
- Adrenal Glands
- Pancreas
- Gonads (Ovaries and Testes)
3
Q
What effect does dysregulation of hormones have on the body? What causes it?
A
Disease can occur
caused by hypo/hypersecretion and/or nonfunctional receptors
4
Q
What are some examples of diseases caused by dysregulation of hormones?
Know Some
A
Type I/II Diabetes
Hypo/Hypersecretion
PCOS
Addison’s Disease
Osteoporosis
Infertitility
Growth Defects
5
Q
Which of the following is NOT an endocrine gland?
A. Ovary
B. Pancreas
C. Lung
D. Thyroid
E. Hypothalamus
A
C. Lung
6
Q
How do cells communicate with each other?
General pathway of cell communication
A
Signal - Receptor - Response
7
Q
What are the types of cellular communication?
A
Autocrine/Paracrine
Endocrine (Hormonal)
Neural
Neuroendocrine
8
Q
What are typical responses seen in cell to cell communication?
A
Opening and closing of ion channels
Phosphorylation of intracellular proteins
Changing cytoskeletal structure
Making new proteins
9
Q
Define
Autocrine Signaling
A
Signal is released by one cell and that signal binds to a receptor on the SAME cell to elicit a response
10
Q
Define
Paracrine Signaling
A
Signal is released by one cell and that signal bnds to a receptor on a different cell in the local area to elicit a response
11
Q
Define
Endocrine/Hormonal Signaling
A
Signal is released by one cell and the signal travels through the blood to reach its target cell
12
Q
Define
Neural Signaling
A
Communication between nerve cells where messages between cells are sent using action potentials and neurotransmitters
13
Q
Define
Neuroendocrine Signaling
A
A nervous cell releases a hormone into the bloodstream where it travels to reach the target cell
14
Q
A cell produces and releases a molecule into the extracellular matrix. This molecule then binds to receptors on the same cell. This most accurately represents which type of cellular signaling?
A
Autocrine signaling
15
Q
What is the pathway of thyroid hormone?
A
- Hypothalamus secretes TRH into bloodstream
- TRH travels to anterior pituitary gland to stimulate release of TSH into bloodstream
- TSH travels through the blood to reach the thyroid gland
- TSH stimulates synthesis and release of T3 and T4 in/from thyroid gland
16
Q
What are the major classes of hormones?
A
Peptide/protein
Catecholamines
Steroid
Iodothyronies or thyroid hormones
17
Q
Hormone behavior depends on…
A
Chemical composition
Form fits function
18
Q
Structure of:
Peptide/protein hormones
A
Unique amino acid sequences
Insulin, GH, ADH
19
Q
Structure of:
Catecholamines
A
Hormones modified from Tyrosine
Amino Acid Derived
Epi, NE, DA
20
Q
Structure of:
Steroid
A
Hormones modified from Cholesterol
Estrogen, Testosterone, Cortisol, Vitamin D
21
Q
Structure of:
Iodothyronies or thyroid hormones
A
Hormones derived from tyrosine and iodine
amino acid derived
T3 and T4
22
Q
Epinephrine is classified as which type of hormone?
A
Catecholamine Hormone
23
Q
Define:
Hydrophilic
A
Soluble in water but not oil
Water loving
Polar
24
Q
Define:
Hydrophobic
A
Soluble in oil but not water
Water Hating
Nonpolar
25
# Define
Lipophilic
Nonpolar
Water hating
Hydrophobic
26
# Define
Lipophobic
Polar
Water Loving
Hydrophilic
27
# Chemical Characteristic
A steroid hormone is...
| Hydrophilic, Hydrophobic, Polar, Nonpolar, Lipophilic, Lipophobic
Hydrophobic
Non Polar
Lipophilic
28
Blood is an aqueous solution. How can hydrophobic (nonpolar) steroid hormones travel through the blood?
| Aqueous = plasma and cells in blood
Bound to binding proteins
29
Binding proteins that have high affinity and low capacity for hormones...
| What does it mean for the transport of hormones?
Have strong binding but cannot move many hormone molecules
30
Binding proteins that have low affinity but high capacity for a hormone...
| What does it mean for the transport of hormones?
Can carry alot of hormone molecules but have weak binding
31
How do SHBG, TBG, and CBG bind steroids?
| Sex-hormone binding globulin, Thyroid BG, Cortisol BG
With high specificty but low capacity
32
How does albumin bind steroids?
It has high affinity to bind to any steroid nonspecifically but with low affinity
33
What is the purpose of binding proteins?
They increase the half - life of hormones so they are not metabolized by liver and kidney
34
What is required before a hydrophobic hormone can be eliminated?
Metabolism by the liver and kidney
35
Free hormones are...
| Not bound
Active
36
Bound hormones are...
Inactive
| Can't enter cells
37
Circulating hormone concentrations depend on....
| What is the equation?
Binding proteins
Total [hormone] = [free hormone] + [bound hormone]
38
Bound hormones represent...
| What is their purpose?
A back-up supply of hormones that can be used when hormone secretion is low
39
If binding protein concentration in the blood increases, what happens to total hormone concentration?
| and [free hormone]?
[Total hormone] increases
[Free Hormone] doesn't change
40
What is the relationship between [total hormone] and binding proteins?
decrease [total hormone] increase release of hormones from binding proteins
41
How are Peptide/Protein Hormones (Polar) produced, processed, and released?
1. DNA
2. Transcription of DNA to mRNA in nucleus
3. mRNA moves to ER by ribosomes for translation into Preprohormone (NH2-signal hormone-copeptides)
4. Unnecessary signals are cleaved in ER to become prohormones
5. Prohormones move to golgi for processing and packaging into hormones
6. hormones and copeptids are released in granules
42
Where are peptide/protein hormones stored?
In granules/vesicles until they are signaled to be released
43
How are catecholamines synthesized?
1. Tryosine converted to DOPA by enzyme 1
2. DOPA converted to Dopamine by enzyme 2
3. Dopamine converted to NE by enzyme 3
4. NE converted to Epi by PNMT
Start with amino acid - then use enzymes to convert to different catecholamines
44
Where are catecholamines made and stored?
| When are they released?
Made and stored in cytosol
| Released when signaled
45
How do polar hormones cross the hydrophobic cell membrane?
They NEED to bind to a receptor embedded in the cell membrane
46
# Define
Ionotropic
Hormone binding directly opens ion channels
47
# Define
Metabotropic
Hormone binding stimulates secondary messenger cascades
48
When protein hormones bind to receptors, cellular responses occur...
| What is their speed?
Fast
milliseconds-minutes
49
Which of the following statements is most accurate concerning polar hormones?
A. Increased numbers of mitochondria will be observed in cells secreting protein hormones
B. Prohormones are modified within the ER
C. Insulin must bind to a receptor embedded in the cell membrane
D. Threonine is enzymatically converted to NE and Epi
E. When protein hormones bind to receptors, cellular responses occur in hours/days.
C. Insulin must bind to a receptor embedded in the cell membrane
50
What is the common precursor of steroids?
Cholesterol
51
Steroids are released....
Immediately
| Not stored in cells
52
What structures are involved in steroid hormone biosynthesis in steroid hormone producing cells?
Mitochondria
Smooth ER
Lipid Droplets
53
What determines which hormons are produced by cells?
Specific enzymes
54
Where are thyroid hormones made?
In a thyroid follicle
55
What makes up a thyroid follicle?
Follicular cells + colloid
56
T3 and T4 are made from...
Iodine and Thyroglobulin (Tg)
| Tg is a protein produced in follicular cells
57
Coupling of Tg and Iodine occurs in....
The colloid
58
What happens to colloid after production of thyroid hormones?
Colloid is endocytosed back into the follicular cells
59
What is the polar behavior of Thyroid Hormones?
T3 and T4 are stored in cytoplasmic vesicles until stimulated by TSH
60
What is the non-polar behavior of T3 and T4?
T3 and T4 travel through the circulation bound to albumin and TBG
61
Most steroid hormones are made in the...
Adrenal Cortex or Gonads
62
Why are steroid hormones not stored in endocrine cells?
Because of their lipophilic nature
They are made on demand and diffuse out of the endocrine cell
63
# Steroid and Thyroid Hormone Signaling
Hydrophobic molecules CAN..., so they bind to...
Hydropobic molecules can pass through the cell membrane so they bind to intracellular receptors in the cytoplasm or nucleus
64
# Steroid and Thyroid Hormone Signaling
What occurs once steroid/thyroid hormones bind intracellular receptors?
Receptors typically dimerize, and then bind to DNA
Genes are up or down regulated (hormone receptor complexes promote or prevent gene transcription and protein translation)
65
Responses to steriod and thyroid signaling are...
| What is their speed?
Slow
Hours - Days
66
NE causes vasoconstriction of vascular smooth muscle in skin, but vasodilation of vascular smooth muscle that perfuses skeletal muscle. How is this possible?
It binds different receptors that couple different transduction pathways and yield different results.
NE binds a1 receptors in vascular smooth muscle in the skin
NE binds b2 receptors in skeletal muscle
67
Which hormone(s) are made in advance and stored in secretory vesicles?
Peptide Hormones
Catecholamines
68
Which hormone(s) are synthesized on demand from precursors?
Steroid Hormones
69
Which hormone(s) are made in advance with their precursor stored in secretory vesicles?
Thyroid Hormones
70
Which hormone(s) are released from parent cells by exocytosis?
Peptide Hormone
Catecholamines
71
Which hormone(s) are released from parent cells by simple diffusion?
Steroid Hormones
72
Which hormone(s) are released from parent cell by transport proteins?
Thyroid Hormones
73
Which hormone(s) are dissolved in plasma for transport through blood?
Peptide Hormone
Catecholamines
74
Which hormone(s) are transported through blood bound to carrier proteins?
Steroid Hormones
Thyroid Hormones
75
Which hormone(s) have a short half life?
Peptide Hormone
Catecholamines
76
Which hormone(s) have a long half life?
Steroid Hormones
Thyroid Hormones
77
Which hormone(s) have receptors located on the cell membrane?
Peptide Hormones
Catecholamines
78
Which hormone(s) can have receptors in the cytoplasm, nucleus, and occasionally the membrane?
Steroid Hormones
79
Which hormone(s) have receptors in the nucleus?
Thyroid Hormones
80
What is the response to ligand binding of Peptide Hormones?
Activation of second messenger systems
May activate genes
81
What is the response to ligand binding of Steroid Hormones?
Activation of genes for transcription and translation
May have nongenomic actions
82
What is the response to ligand binding of Catecholamines?
Activation of second messenger systems
83
What is the response to ligand binding of Thyroid Hormones?
Activation of genes for transcription and translation
84
What is the general target response of peptide hormones?
Modification of existing proteins and induction of new protein synthesis
85
What is the general target response of steroid and thyroid hormones?
Induction of new protein synthesis
86
What is the general target response of catecholamines?
Modification of exisiting proteins
87
Examples of Peptide Hormones
Insulin
Parathyroid Hormone
88
Examples of Steroid Hormones
Estrogen
Androgens
Cortisol
89
Examples of Catecholamines
Epi
NE
Dopamine
90
Example of Thyroid Hormones
T3 and T4
91
What is the behavior of Peptide Hormones?
| Summary of Table
Made in Advance; stored in secretory vesicles
Released by exocytosis
Transported through blood dissolved in plasma
Short Half life
Receptor located on cell membrane
When receptor is bound activation of second messanger system; may activate genes
General Target Response is modification of exisiting proteins and induction of new protein synthesis
92
What is the behavior of Catecholamines?
| Summary of Table
Made in Advance; stored in secretory vesicles
Released by exocytosis
Transported through blood dissolved in plasma
Short Half life
Receptor located on cell membrane
When receptor is bound activation of second messanger system
General Target Response is modification of exisiting proteins
93
What is the behavior of Steroid Hormones?
| Summary of Table
Synthesized on demand from precursors
Released by simple diffusion
Transported through blood bound to proteins
Long Half life
Receptor located in cytoplasm and nucleus (sometimes cell membrane)
When receptor is bound activation of genes for transcription and translation; may have nongenomic actions
General Target Response is induction of new protein synthesis
94
What is the behavior of Thyroid Hormones?
| Summary of Table
Made in advance; precursor stored in secretory vesicles
Released by transport proteins
Transported through blood bound to proteins
Long Half life
Receptor located in nucleus
When receptor is bound activation of genes for transcription and translation
General Target Response is induction of new protein synthesis
95
This hormoneis stored in vesicles within the cell until its stimulated to be released. Upon release, it binds to a bindingn protein to travel through the blood. It travels to its target cell and binds to an intracellular receptor. What hormone and I?
A. Estrogen
B. Insulin
C. Oxytocin
D. T3
E. Epi
D. T3
| Polar and nonpolar characteristics
96
What hormones are secreted by the hypothalamus?
TRH
Dopamine
CRH
GnRH
SS
97
What hormones are secreted by the Anterior Pituitary?
TSH
FSH
LH
GH
ACTH
Prolactin
| Tropic Hormones - stimulate release of hormones from target gland
98
What hormones are secreted by the Posterior Pituitary?
ADH
Oxytocin
99
What hormones are secreted by the thyroid gland?
T3
T4
Calcitonin
100
What hormones are secreted by the Parathyroid Gland?
PTH
101
What hormones are secreted by the Adrenal Glands?
Cortex: Cortisol, Aldosterone, Androgens
Medulla: Epi, NE
102
What hormones are secreted by the Pancreas?
Insulin
Progesterone
SS
103
What hormones are secreted by the Ovaries?
Estradiol
Progesterone
Inhibin
104
What hormones are secreted by the Testes?
Testosterone
Inhibin
105
What hormones are secreted by the Liver?
IGF-1
106
Homeostasis is regulated through...
negative feedback
107
What is the negative feedback loop that occurs after a person eats food?
Eat food → ↑Blood Glucose → Pancreas senses ↑Blood Glucose → insulin is released → insulin travels to the skeletal muscle → insulin stimulated ↑ uptake of glucose into muscle cells
| The response counteracts the initial stimulus to decrease blood glucose
108
Physiological Response - Driven Negative Feedback
Endocrine gland → Release of Hormone → Travels to target organ → Physiological Effects → Circulating component → Negative feed back on original endocrine gland
109
Endocrine Axis-Driven Negative Feedback
Hypothalamic Neurodendocrine Neurons → Releases releasing hormone → stimulates pituitary gland → releases tropic hormone → travels to peripheral endocrine gland → releases hormone
Hormone can continue forward to target organs → physiological effects
OR
Hormone can feedback to the pituitary gland and Hypothalamic neuroendocrine neurons for negative feedback of the initial stimulus
110
If TRH release stopped, what would happen to TSH?
↓TSH
111
If TRH release stopped, what would happen to T3 and T4?
↓T3 and ↓T4
112
If too much TSH was released what would happen to T3 and T4?
↑T3 and ↑T4
113
If too much T3 or T4 was released, what would happen to TRH?
↓TRH
114
If too much T3 or T4 was released, what would happen to TSH?
↓TRH
115
What happens when less active hormones are secreted?
They are converted by enzymes to a more active form in tissue
116
T4 is converted to...
T3
117
Vitamin D3 is converted to...
1,25 (OH)2D3
118
Angiotensinogen is converted to...
Angiotensin II
119
What would happen if you blocked a key enzyme?
| What's an ACCE inhibitor and why is it used?
Conversion wouldn't occur
Less active form would remain in circulation
