BIPN 100 Lecture Notes - Lecture 12: Cyclic Adenosine Monophosphate, Hydrophile, Calcitriol

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28 Jun 2018

School

UCSD

Department

Biology/Animal Physiol & Neurosc

Course

BIPN 100

Professor

Catalina Reyes Gonzales

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BIPN100 Lecture 12 Notes 4/30/18

- Hormones: chemical signal secreted by a cell or group of cells

oTransported by blood

Can be transported to a distant target

Slower response compared to nervous system signal

Activates physiological responses at low concentrations

oBinds to target cell receptors to initiate biochemical responses

One hormone may act on multiple tissues if the receptors for the hormone are

present

Effects may vary in different tissues depending on the type of receptor

Ex: epinephrine can cause opposite responses based on the receptor they bind

(excitatory vs. inhibitory response)

Pheromones elicit a physiological or behavioral response on other organisms of the

same species

- Types of hormone release

oEndocrine: hormones released into blood and distributed broadly

oParacrine release: hormones only affect neighboring cells

oAutocrine: target is itself. Cell controls its own release of hormone

oNeurocrine: hormone released by neurons (chromaffin cells that release E in blood)

- Types of hormones

oSteroid hormones: cholesterol derived

Made in few organs

Adrenal cortex (outer part of adrenal gland) makes cortisol and aldosterone

Gonads and placenta make estrogen, progesterone, and testosterone

Lipophilic: can easily cross membranes through diffusion

Not very soluble in plasma

Bind carrier proteins in the blood: gives them a longer half-life

Generally bind to cytoplasmic or nuclear receptors

Can activate or repress genes for protein synthesis

Slower acting

some hormones act on membrane receptors using second messengers

cause nongenomic responses

oamino acid-derived or amines

derived from:

tryptophan: melatonin

tyrosine: catecholamines and thyroid hormones

othyroid hormones (T3 and T4): attached iodine atoms to tyrosine

opeptides or proteins

water soluble; dissolve easily in the ECF for transport

short half-life because not bound to protein in the blood

peptide: short chains of amino acids (ADH and oxytocin)

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protein hormones: long chains of amino acids (insulin and human growth hormone)

oeicosanoids

roles

participate in inflammatory responses

intensity and duration of pain and fever

reproduction function (induction of labor)

inhibitor of gastric acid secretion

BP control (vasodilation or vasoconstriction)

Activation or inhibition of platelet aggregation

Produced from oxidation of arachidonic acid (20 carbon polyunsaturated fatty acid)

If oxidized by COX, produces prostaglandins, which can be converted into

prostacyclins (produced in wall of blood vessels; cause vasodilation and prevent

aggregation of platelets/clotting) and thromboxanes (cause vasoconstriction and

activate platelet aggregation/clotting)

If oxidized by LOX, produces leukotrienes (Produced by immune cells to mediate

inflammation. Cause constriction/inflammation in bronchioles)

- Solubility of hormones

oLipid-soluble hormones

Can cross phospholipid bilayer

Must be transported in blood using protein carrier

Cross membrane to act on cytoplasmic or nuclear receptors to

affect transcription and translation. Sometimes act on

membrane receptors

Steroid and thyroid hormones (T3 and T4) are lipid-soluble

Eicosanoids are lipid soluble, but use membrane bound receptors

(Gs, Gi, and Gq). Most act locally

oWater-soluble hormones

Can go without carrier in blood, but cannot cross lipid bilayer

Bind to membrane receptor, generally coupled to G proteins (GCPRs)

to start cellular responses through second messengers

Peptide and protein hormones, and catecholamines

oReview of GPCRs

Gs: hormone binds to receptor coupled to G protein. Gs alpha

subunit unbinds from gamma and beta subunits, and GDP exchanged for GTP,

causing alpha subunit to go to effector to activate it. AC converts ATP to cAMP (2nd

messenger). cAMP activates protein kinase A, which phosphorylates other proteins

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Document Summary

Hormones: chemical signal secreted by a cell or group of cells: transported by blood. Can be transported to a distant target. Activates physiological responses at low concentrations: binds to target cell receptors to initiate biochemical responses. One hormone may act on multiple tissues if the receptors for the hormone are present. Effects may vary in different tissues depending on the type of receptor. Ex: epinephrine can cause opposite responses based on the receptor they bind (excitatory vs. inhibitory response) Pheromones elicit a physiological or behavioral response on other organisms of the same species. Types of hormone release: endocrine: hormones released into blood and distributed broadly, paracrine release: hormones only affect neighboring cells, autocrine: target is itself. Cell controls its own release of hormone: neurocrine: hormone released by neurons (chromaffin cells that release e in blood) Types of hormones: steroid hormones: cholesterol derived. Adrenal cortex (outer part of adrenal gland) makes cortisol and aldosterone.

Related Questions

1. Be able to define the following terms: releasing hormone,inhibiting hornone, trooic hormone, nontropic hormones,neurosecretory cells.

2. What are hormones?

3. What are two specific differences between the endocrine andnervous systems?

4. What are the four different types of cell signaling?

5. What are the three types of hormonal control pathways? Givean example of each.

6. What is local regulator?

7. What type of feedback is a common feature of pathways thatcontrol homeostasis?

8. What are the three major classes of molecules that functionas hormones? Which are water-souble and which are lipid-souble?

9. Signaling by a hormone involves three key events. What arethey?

10. What is the correlation between solubility of a hormone andthe location of its receptors?

11. In addition to receptor location, water-soluble andlipid-soluble hormones also exhibit additional differences in theirresponse pathways. What are these differences?

12. What is signal transduction pathway?

13. Why can the same hormone have different effects on differentbody tissues?

14. Liver cells and the blood vessels of skeletal muscle cellshave identical surface receptors for epinephrine, yet the responeof these two cells types is dramatically different. Explain howthis is possible.

15. In the "fight or fight response" the release of epinephrinefrom the adrenal medulla cause skeletal muscle blood vessels todilate while simultaneously constricting blood vessels of theintestine. Explain how this is possible.

16. List the three types of local regulators discussed in classand explain their function.

ochremule554

The insulin receptor is a
a. phosphatase.
b. kinase.
c. phosphodiesterase.
d. cAMP molecule.
e. G protein.

What do the following receptors all have in common: G protein-linked receptors, protein kinases, and ion channels?
Select one:
a. Conformational change once the ligand is bound
b. Ligand binding
c. Amplification of the signal
d. All of the above

Diacylglycerol
Select one:
a. activates G proteins.
b. hydrolyzes phosphatidyl inositol-bisphosphate.
c. is released from the cell as a paracrine-signaling molecule.
d. opens Ca2+ channels.
e. activates protein kinase C

Gap junctions
Select one:
a. permit metabolic cooperation among linked cells.
b. are present on few copies per cell.
c. contain membrane lined bridges.
d. are channels about 1. 5 mm in diameter.
e. allow large molecules and ions to pass rapidly between cells.

Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine. What would you expect to be different in these two types of cells exposed to epinephrine?
Select one:
a. Presence of epinephrine receptors.
b. Exposure to epinephrine released by neighboring cells.
c. Activation of protein kinases.
d. Rate of metabolism.
e. Types of proteins expressed.

The second messenger IP3
Select one:
a. is released from the cell as a paracrine-signaling molecule.
b. hydrolyzes phosphatidyl inositol-bisphosphate.
c. activates protein kinase C.
d. opens Ca2+ channels.
e. activates G proteins.

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BIPN 100 Lecture Notes - Lecture 12: Cyclic Adenosine Monophosphate, Hydrophile, Calcitriol

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