Lecture 2 Flashcards
(79 cards)
0
Q
Which mammalian hormones have feedback regulation of synthesis
A
Steroids
Thyroxine derivatives
Peptides and proteins
Catecholamines
1
Q
Three major classes of human hormones
A
Protein and peptide hormones
Steroid hormones
Tyrosine derivatives
2
Q
How long is storage of preformed steroid hormones
A
Very little
3
Q
Storage of preformed thyroxine
A
Several weeks
4
Q
Storage of peptide hormones
A
One day
5
Q
Storage of catecholamines
A
Several days, in adrenal medulla
6
Q
Mechanism of secretion, steroids
A
Diffusion through plasma membrane
7
Q
Thyroxine mechanism of secretion
A
Proteolysis of thyroglobulin
8
Q
Mechanism of secretion peptides
A
Exocytosis of storage vesicles
9
Q
Mechanism of secretion catecholamines
A
Exocytosis of storage vesicles
10
Q
Binding to plasma proteins - steroids
A
Yes
11
Q
Binding to plasma proteins - thyroxine
A
Yes
12
Q
Binding to plasma proteins - peptides
A
Rarely
13
Q
Binding to plasma proteins- catecholamines
A
No
14
Q
Lifetime in blood plasma - steroids
A
Hours
15
Q
Lifetime in blood plasma-thyroxine
A
Days
16
Q
Lifetime in blood plasma-peptides
A
Minutes
17
Q
Lifetime in blood plasma- catecholamines
A
Seconds
18
Q
Time course of action-steroids
A
Hours to days
19
Q
Time course of action-thyroxine
A
Days
20
Q
Time course of action-peptides and proteins
A
Minutes to hours
21
Q
Time course of action-catecholamines
A
Seconds or less
22
Q
Receptors -steroids
A
Cytosolic or nuclear
23
Q
Receptors - thyroxine
A
Nuclear
24
Receptors - peptides and proteins
Plasma membrane
25
Receptors - catecholamines
Plasma membrane
26
Mechanism of action - steroids and thyroxine
Receptor-hormone complex controls
| Transcription and stability of mRNAs
27
Mechanism of action - peptides
Hormone binding triggers synthesis of Cytosolic second messengers or protein kinase activity
28
Mechanism of action - catecholamines
Hormone binding causes change in membrane potential or triggers synthesis of Cytosolic second messengers
29
Two classes of hormone receptors
Intracellular
| Cell surface
30
How does negative feedback system work
A product sends message back to source to cut back production
31
How does positive feedback loop work
Product sends message bsck to source to make more product
32
How is parturition an example of a positive feedback loop
Posterior pituitary makes oxytocin, which produces uterine contraction, which creates a cervical stretch as baby's head is pushed forward. Stretch sends positive feedback to posterior pituitary to make more oxytocin and to uterus to contract more
33
How does two hormone feedback system work
As one increases, the other decreases and vice versa
34
What controls activity of thyroid glands, adrenal cortex, and gonads
Feedback effects of their circulating hormones on the hypothalamic-pituitary axis
35
What controls pancreas and parathyroid
Feedback signals of regulated variable
36
Six experimental approaches used in endocrinology research
```
Surgical approach
Parabyosis
Immunological- immunolocalization and radioimmunoassay
Ligand receptor binding
Bioassay
Gene manipulation (molecular biology)
```
37
Explain the Berthold experiment with roosters (concept of compensatory hypertrophy) surgical approach
Group I had both testes removed
Group II had one testis replaced
Group III had one testis exchanged
Results
I. comb and wattles small, no interest in hens, weak crow, listless fight behavior
II. Comb and wattles normal, interest in hens, normal crow, aggressive fight behavior, testis larger than in controls
III. Same as II
38
Parabyosis
The joining of two individuals
39
Example of Parabyosis experiment
Surgically achieved shared circulation in mice. Compensatory organ hypertrophy.
40
Immunolocalization
Using immunologic techniques, including specific antibody, to identify location of molecules or structures within cells or tissues
41
Radioimmunoassay
Technique for determining antibody levels by introducing an antigen labeled with a radioisotope and measuring the subsequent radioactivity of the antibody component
42
Immunodeficiency assay
Antibodies immobilized into a plastic surface are used to capture the target antigen
Second antibody linked to enzyme is then added. It binds to a different location on target antigen.
Plate wells are washed to remove unbound components
Substrate is added
Enzymatic reaction is stopped in order to establish a consistent time period for all wells. After stopping, color is measured.
Color generated is directly proportional to the amount of analyze present.
43
Concept of immunometric assay
Antigen specific antibody is attached to a solid-phase surface
Test specimen is added, which may or may not contain the antigen
An enzyme labeled antibody specific to the antigen is added
Chromogenic substrate is added, which in the presence of the enzyme, changes color.
44
What is relationship between hormone binding and biological response when there are spare hormone receptors
The concentration of hormone can be smaller if there are spare receptos to achieve the same amount of binding as it would take with fewer receptors
45
Amino acid derivatives that interact with cell surface receptors
Epinephrine and histamine
46
Where does epinephrine originate? Major effects?
Adrenal medulla
Increase in pulse rate and blood pressure, contraction of most smooth muscles, glycogenolysis in liver and muscle, hydrolysis in adipose tissue
47
Histamine origin and effects
Mast cells
| Dilation of blood vessels
48
Do prostaglandins react with cell surface receptors
Yes
49
What are prostaglandins a derivative of
Arachnid panic acid
50
Origins and major effects of prostaglandins
Most body cells
| Contraction of smooth muscle
51
Examples of peptide hormones that interact with cell surface receptors
```
Follicle stimulating hormone (FSH)
Glucagon
Insulin
LH releasing hormone
Luteinizing hormone
```
52
Source and effects of FSH
Anterior pituitary
| Stimulates growth of oocyte and ovarian follicles and estrogen synthesis by follicles
53
Sources and effects of glucagon
Pancreas alpha cells
| Stimulates glucose synthesis and glycogen degradation in liver; lipid hydrolysis in adipose tissue
54
Source and effects of insulin
Pancreas beta cells
Stimulates glucose uptake into fat and muscle cells; carbohydrate catabolism, stimulates lipid synthesis by adipose tissue; general stimulation of protein synthesis and cell proliferation
55
Source and effects of LH releasing hormone
Hypothalamus, neurons
| Induces secretion of LH by anterior pituitary
56
LH source and effects
Anterior pituitary
| Maturation of oocyte, stimulates estrogen and progesterone secretion by ovarian follicles
57
Examples of peptide growth/differentiation factors that interact with cell surface receptors
Epidermal growth factor
Nerve growth factor
Platelet derived growth factor
58
Source and effects of insulin like growth factor 1
Liver and other cells
Autocrine/paracrine growth factor induced by somatotropin; stimulates cell growth and division and glucose and amino acid uptake, increase in liver glycogen synthesis
59
Nerve growth factor origin and effects
All tissues innervated by sympathetic neurons
| Growth and differentiation of sensory and sympathetic neurons
60
Platelet-derived growth factor origin and effects
Platelets and cells in many other tissues
Chemotaxis of connective tissue cells and inflammatory cells; development and survival of cells in the nervous system;wound healing
61
What are the two types of cell surface receptors
Linked to TK
| Linked to G proteins
62
What are the two subgroups of receptors linked to TK
Growth factor receptors intrinsic TK
| Cytokines receptors recruit TK
63
Two types of subgroups of receptors linked to G proteins
Adenylate cyclase
| PLC
64
Two types of intracellular receptors
Class 1 Cytosolic
| Class 2 nuclear
65
Mechanism of action of G protein linked receptors
1. Ligand binds with cell surface receptor
2. Conformational change in receptor
3. Receptor binds to G alpha protein
4. Induces conformational change in G alpha
5. GDP bound to G alpha is replaced by GTP and the subunit disassociates from Gbetagamma
6. G alpha binds to adenylyl Cyclase and activates cAMP synthesis
7. Hormone dissociates
8. Hydrolysis of GTP to GDP causes G alpha to dissociate from adenylyl Cyclase and bind to Gbetagamma
66
Five second messengers
```
3',5'-cyclic AMP
3',5'- cyclic GMP
1,2- diacylglycerol
Inositol 1,4,5- triphosphate
Calcium ion
```
67
What does binding of growth hormone do to receptor? What does it recruit?
Dimerization of receptor
| Recruits cytoplasmic tyrosine kinase,JAK-2
68
Where does JAK-2 bind in GH receptor
Juxta membrane region of intracellular domains of receptor, known as Box 1
69
What does JAK-2 activate
MAPK
70
What does JAK-2 phosphorylate
Tyrosines on STATs
| They form dimers and undergo translocation into nucleus, where they act as transcriptional regulatory proteins
71
How does GH rapid insulin-like metabolic effects
IRS-1 and IRS-2 are phosphorylated by JAK-2 and recruit p85 subunit of P13 kinase
72
What is the structure of the insulin receptor
Disulfide bridges link the alpha subunits to one another and also to two identical beta subunits, which cross the plasma membrane.
73
What does insulting binding to receptor result in?
Insulin binding to alpha subunits in auto phosphorylation of the intracellular domains of the beta subunits
74
What does phosphorylation of insulin receptor beta subunits cause
Docking of IRS-1 or IRS-2, which can then be activated by tyrosine phosphorylation P
75
How does MAPK pathway work in insulin receptor
Grb2 links IRs-1 to the GDP/GTP exchange protein, Sos. The Sos Grb2 complex gets near small G protein RAs, located in plasma membrane. This triggers RAs by the exchange of GTP for GDP.
Serine/threonine kinase enzyme Raf activates a tyrosine/serine/threonine kinase enzyme (MEK), which activates a multifunctional MAPK, which targets proteins located in multiple regions of cells
76
What can MAPK modulate in insulin receptor
C-fos and c-junk and can also release arachidonic acid by the action of phospho lipase A2
77
What do IRS1 or 2 activate via insulin receptor
The P13 kinase pathway which enhances glucose transport
78
Mechanism of steroid hormone receptor
Serum binding protein transports steroid hormone to vicinity of membrane
Hormone diffuses through membrane
It bind with Cytosolic receptor
Enters nucleus and influences trancription
Mature MRNA exists nucleus and goes to ribosome complex, where it is translated into a protein
