ADPHY: Introduction to Membranes Pt. 2 Flashcards
1
Q
How do cells communicate with each other?
A
Chemical messengers.
2
Q
What are the 4 ways cells communicate?
A
- Gap junctions.
- Neural communication.
- Endocrine communication.
- Paracrine communication.
3
Q
How is a message transmitted via gap junctions?
A
Directly from cell to cell.
4
Q
Is the transmission of a message via a gap junction local or general?
A
Local.
5
Q
What does the specificity of gap junctions depend upon?
A
Anatomic location.
6
Q
How is a message transmitted in neural signaling?
A
Across the synaptic cleft.
7
Q
Is the transmission of a message via neural signaling local or general?
A
Local.
8
Q
What 2 things does the specificity of neural signaling depend upon?
A
- Anatomic location.
- Receptors.
9
Q
How is a message transmitted in paracrine signaling?
A
By diffusion though interstitial fluid.
10
Q
Is the transmission of a message via paracrine signaling local or general?
A
Locally diffuse.
11
Q
What does the specificity of paracrine signaling depend upon?
A
Receptors.
12
Q
How is a message transmitted in endocrine signaling?
A
Utilizing circulating body fluids.
13
Q
Is the transmission of a message via endocrine signaling local or general?
A
General.
14
Q
What does the specificity of endocrine signaling depend upon?
A
Receptors.
15
Q
What are gap junctions?
A
An organized collection of protein channels in cell membranes that allow ions and small molecules to pass between adjacent cells.
16
Q
What are protein channel composed of?
A
Two connexons.
17
Q
How many connexons does each cell membrane hold?
A
1 per gap junction.
18
Q
What are the subunits that form a connexon? How many form a connexon?
A
- Connexins.
- 6.
19
Q
What 2 cells in the body contain gap junctions?
A
- Sertoli cells.
- Cardiac cells.
20
Q
How are signals communicated in neural communication?
A
Neurotransmitters are released into the synaptic cleft onto the postsynaptic cell or effector tissue.
21
Q
What is an example of a paracrine reaction?
A
An asthma attack.
22
Q
What happens during an asthma attack?
A
Mast cells in the bronchioles of the lungs release slow reacting substance of anaphylaxis, causing the spasm and constriction of bronchiolar smooth muscles.
23
Q
What is an anaphylactic reaction?
A
An allergic reaction that is usually severe or life-threatening.
24
Q
What type of antibodies are released during an anaphylactic reaction?
A
IgE.
25
What 2 white blood cell types are most active during an anaphylactic reaction?
1. Mast cells.
2. Basophils.
26
What 3 substances do the 2 white blood types release during an anaphylactic reaction?
1. Histamines.
2. Leukotrienes.
3. Prostaglandins.
27
What 4 reactions occurs as a result of the release of these 3 substances during an anaphylactic reaction?
1. Increased blood capillary permeability.
2. Increased mucus secretion.
3. Increased smooth muscle contraction in the airways.
4. Vasodilation.
28
What happens to arterial pressure and cardiac output during an anaphylactic reaction? Why?
1. It decreases.
2. Due to vasodilation allowing for increased blood flow throughout the body.
29
What happens as a result of the increased smooth muscle contraction in airways during an anaphylactic reaction?
Wheezing and shortness of breath.
30
What are the 3 reason receptors are needed in chemical signaling?
1. When the message needs to travel a long distance.
2. A specific tissue is targeted.
3. The chemical messenger is large or highly polar.
31
What are receptors?
Protein structures that bind chemical messengers and relay the signal to the cell/tissue.
32
Where are the 2 places receptors are found?
1. Cell membrane surface.
2. Cytoplasmic/Nuclear surface.
33
What kind of chemical messengers interact with receptors on the cell membrane surface?
Large and/or polar ones.
34
What kind of chemical messengers interact with receptors on the cytoplasmic/nuclear surface?
Lipid soluble compounds.
35
What is the primary role of epinephrine in the body?
The management of the fight or flight response. What it does specifically depends on what receptor it stimulates.
36
What are the 2 main types of epinephrine receptors?
1. a.
2. B.
37
Can a tissue have different receptors?
Yes.
38
What is an example of a tissue with different receptors?
Uterine myometrium.
39
How is it possible for a hormone to work two ways on the same tissue?
1. Two types of receptors with different affinities are present.
2. Different G proteins and second messengers associated with each receptor.
40
What does epinephrine binding to the a1 receptor on the uterine myometrium cause?
It stimulates contractions.
41
What does the cascade look like for a1 receptor stimulation?
1. Hormone-receptor complex forms and causes a conformational change.
2. G-Protein Gp is activated as a result of the conformational change, resulting in the release of the second messenger IP3.
3. The second messenger IP3 interacts with the ER, leading to the release of Ca2+.
4. Ca2+ floods the cell, causing a contraction.
42
What does epinephrine binding to the B2 receptor on the uterine myometrium cause?
It inhibits contractions.
43
What does the cascade look like for the B2 receptor stimulation?
1. Hormone-receptor complex forms and causes a conformational change.
2. G-Protein Gs is activated as a result of the conformational change, resulting in the release and upregulation of cAMP.
3. The second messenger PKA is released and it phosphorylates a Ca2+ efflux pump.
4. Ca2+ is removed from the cell, causing relaxation.
44
What are hormones?
Substances synthesized in one organ and transported by the circulatory system to act on another tissue.
45
What are the 4 ways to classify a hormone?
1. Chemical composition.
2. Receptor location.
3. Solubility.
4. Nature of signal used to mediate action.
46
What are the 2 chemical compositions of hormones?
1. Steroids, iodothyronines, calcitriol, retinoids. Group 1.
2. Polypeptides, proteins, glycoproteins, catecholamines. Group 2.
47
What is the solubility of Group 1 hormones?
Lipophilic.
48
What is the solubility of Group 2 hormones?
Hydrophilic.
49
Do Group 1 hormones require transport proteins to cross the cell membrane?
Yes.
50
Do Group 2 hormones require transport proteins to cross the cell membrane?
No.
51
What is the plasma half-life of Group 1 hormones?
Long (hours to days).
52
What is the plasma half-life of Group 2 hormones?
Short (minutes).
53
Where is the receptor for Group 1 hormones found?
Intracellular.
54
Where is the receptor for Group 2 hormones found?
Plasma membrane.
55
What is the mediator for Group 1 hormones?
The receptor-hormone complex.
56
What is the mediator for Group 2 hormones?
1. cAMP.
2. cGMP.
3. Ca2+ metabolites of complex phosphoinositols.
4. Kinase cascades.
57
In second messenger systems, what do hormones act as?
Signals.
58
In second messenger systems, what do receptors act as?
Signal detectors.
59
What do second messenger systems serve as the link between?
Extracellular events and chemical changes in the cell.
60
What happens when hormones bind to receptors?
A series of reactions is initiated that trigger specific intracellular responses.
61
What are the 2 most common second messengers?
1. Adenyly cyclase (cAMP).
2. Phosphotidylinositol/Ca2+.
62
What are the basic components of the cAMP second messenger system?
1. G-Protein.
2. Adenylyl cyclase.
3. cAMP.
4. Protein kinase.
63
What are the steps of the adenylyl cyclase second messenger system?
1. Adrenergic receptor activation by the binding of a chemical messenger.
2. G-Protein interaction due to a conformational change in the adrenergic receptor.
3. The G-Protein specific to the adenylyl cyclase leads to the activation of adenylyl cyclase.
4. ATP is converted to cAMP as a result of adenylyl cyclase activation.
5. cAMP binds to protein kinase, leading to the dissociation of protein kinase into its regulatory and catalytic subunits.
6. The catalytic subunit of the protein kinase becomes activated.
7. A phosphate from ATP is transferred to the protein substrates.
8. Protein substrates act in a variety of manners dependent on cell need.
64
What are the basic components of the Ca2+ second messenger system?
1. G-Protein.
2. Ca2+.
3. Phospholipase.
4. PIP2.
65
What are the steps of the Ca2+ second messenger system?
1. Adrenergic receptor activation by the binding of a chemical messenger.
2. G-Protein interaction due to a conformational change in the adrenergic receptor.
3. PIP2 is degraded by phospholipase C in response to chemical messenger binding.
4. The resulting products are IP3 and DAG.
5. DAG activates protein kinase C.
6. IP3 releases Ca2+ from the endoplasmic reticulum.
7. The phosphorylated proteins mediate cellular responses to hormones.
66
What are the 3 ways a phosphorylated protein substrate may act in a cell?
1. Act on ion channels.
2. Act on enzymes for activation or inhibition.
3. Bind to a promoter region of DNA to increase gene expression.
67
What is the function of protein phosphatase?
An enzyme that hydrolytically cleaves phosphates from proteins.
68
What is the function of phosphodiesterase?
Hydrolyzes cAMP.
69
What are 2 examples of where cAMP is used in the body?
1. Thyroid (T3 and T4 formation).
2. Renal tubules (Increase or decrease in permeability of water).
70
What is the relationship between cholera toxin and G-Protein?
Cholera bacteria produces a toxin that modifies the G-Protein in the intestinal epithelium to be locked in an active state, upregulating cAMP. This upregulation causes a mass efflux of Cl-, Na+, and water into the intestinal lumen. Ultimately, this all leaves the body in the form of watery diarrhea.
71
How is cholera treated?
1. Fluid replacement.
2. Ab treatment with tetracyclines.
72
What are lipophilic hormones?
Hormones that can pass through the plasma membrane and bind to intracellular receptors to form hormone receptor complexes.
73
What 3 lipophilic hormones have cytoplasmic receptors?
1. Glucocorticoids.
2. Mineralocorticoids.
3. Androgens.
74
What is an example of a glucocorticoid?
Cortisol.
74
What is an example of a mineralocorticoid?
Aldosterone.
75
What is an example of an androgen?
Testosterone.
76
What 5 lipophilic hormones have nuclear receptors?
1. Thyroid hormones.
2. E2.
3. Retinoic acid.
4. P4.
5. 1,25-dihydroxy vitamin D3.
77
What specific DNA sequence do activated lipophilic hormone receptors bind to?
Hormone Response Elements.
78
Where is the hormone response element located in the DNA sequence?
In the promoter region.
79
What does binding to the hormone response element cause to occur?
Acceleration of gene transcription and production of appropriate mRNA.
80
What are the 2 downstream effects of the binding to the hormone response element?
1. Increased amounts of specific proteins are changed.
2. Metabolic processes are influenced.
81
What are steroid hormones?
Hormones that form receptor-ligand complexes that accumulate in the nucleus.
