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Cell Signaling/HORMONES
Kumar
36
Biology
Professional
08/20/2008

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Term
What are examples of Hydrophilic hormones?
Definition
  • Peptide hormones (amino acids)
  • proteins, glycoproteins, catecholamines(epinepherine)
Term
Where are Hydrophilic hormones synthesized?
Definition

Endocrine cells RER

 

Can be stored in vesicles until needed.

Term
Where are the Hydrophilic hormone receptors found?
Definition
Cell surface of target cell
Term
How long is the plasma half-life of a hydrophilic (lipophobic) hormone?
Definition
Short (minutes)
Term
What are the mediators of hydrophilic hormones?
Definition
  • cAMP
  • cGMP
  • Ca2+
  • metabolite
  • Protein kinase activity
Term
What are examples of Hydrophobic hormones?
Definition
  • Steroids
  • Iodothyromines
  • Calcitriol
  • Retinoids
Term
How long is the plasma half-life fo a hydrophobic hormone?
Definition
Hours to days
Term
Where are the receptors for hydrophobic hormones located?
Definition

Either the cytosol(cortisol) or in the nucleus.

Term
What is the role of the Receptor-Hormone complex?
Definition

Mediators

 

Turns on/off specific genes for mRNA.

Term
Describe the process of the Gs protein activating Adenylate cyclase?
Definition
  1. Hormone (glucagon/epinepherine) binds with receptor and induces conformational change.
  2. Activated receptor binds to Gs protein (Gα subunit)
  3. G protein conformational change. It's GDP is replaced by GTP.
  4. Gα detaches from Gβγ and activates/binds Adenylate Cyclase.
Term

Which hormones would have the longest duration of action?

Definition

Lipophilic hormones

 

T3 and T4

Term
What inhibits Adenylate cyclase?
Definition

Gi ("i" for inhibit)

 

Gi is turned on by Adenosine and PGE1

Term
What is the Hormone Response Element?
Definition

HRE

 

8-15 base pairs on the DNA molecule that receptor-hormone complex binds to.

Term
What second messenger can activate Protein Kinase A (PKA)
Definition
cAMP
Term

What 2nd messenger can activate cGMP-Dependent protein kinase?

Definition
cGMP
Term
What stimulates Phospholipase C?
Definition
Gq
Term
How does Phopholipase C work?
Definition
  • Membrane bound enzyme
  • Hydrolyses PIP2→IP3
  • IP3 and DAG work together to activate Protein Kinase C. PKC 
Term
What hormones have nuclear cell receptors?
Definition
  • Thyroid hormones (T3 and T4)
  • Retinoids
  • Vitamin D

Their receptors bind to the promoter region of the DNA.

Term
Describe the formation and Hydroxylation of Vitamin D3 (cholecalciferol):
Definition
  • 7-Dehydrocholesterol(provitamin D3) is nonenzymatic photolysis by ultraviolet light to form previtamin D.
  • Somehow previtamin D→ Vitamin D3
  • Vitamin D3→ 25-hydroxycholecalciferol (25-hydroxylation in the Liver)
  • Other hydroxylations occur in the kidneys.
Term
Endocrine vs. Paracrine vs. Autocrine action
Definition

Endocrine: the hormone is distributed in the blood and binds to distant target cells.

Paracrine: hormone acts on a neighboring cell.

Autocrine: hormone acts on cell that releases it.

Term
Signaling between cells usually results in the activation of protein.....
Definition
kinases
Term
What second messenger activates Protein kinase A? kinase G?
Definition

cAMP

cGMP

Term
What are specific examples of hormones that are not stored? stored the longest?
Definition

Not stored: Steroids and 1,25(OH)-D3

 

Weeks: T3 - T4

Term
What does Nitric Oxide mainly activate?
Definition

It activate cGMP in the cytosol which activates PKG (protein kinase G)

Term
What do Pancreatic β cells secrete?
Definition
Insulin and C peptide
Term
Does cell signaling stimulate apoptosis?
Definition
NO
Term
Small G proteins(like RAS) convert GTP→ GDP by:
Definition
Phosphatase activity
Term
IP3 induces cellular response by increasing cytoplasmic..
Definition
[Ca+]
Term
What signals Progesterone? What secretes it?
Definition

LH

 

Ovaries (corpus luteum)

Term
What signals Estradiol? What releases it?
Definition

FSH

 

Ovary

Term
What stimulate Testosterone? What secretes it?
Definition

LH

 

Testis (adrenal gland)

Term
What stimulates DHES? What releases it?
Definition

ACTH

 

Reticularis

Term
What stimulates (Glucocorticoids)Cortisol? What secretes it?
Definition

ACTH

 

Adrenal Cortex

Term
What stimulates Aldosterone? What releases it?
Definition

Angiotensin II/III

 

Adrenal Cortex

Term
What stimulates 1,25-Dihydroxy..(Vitamin D)? What secretes it?
Definition

PTH

 

Kidney

Term
What are the different classes of hormones?
Definition

Protein hormones: membrane receptors. Fastest

-Oxytocin, Adrenocorticotrophin

 

Amine hormones: membrae receptors. Kinda fast.

-Epinepherine, Norepinepherine, Melatonin

 

Steroid and other small hormones: Intercellular receptors. Slow.

-Gonad hormones: estrogen, progesterone, androgens(testosterone)

-Adrenal hormones: glucocorticoids, mineralcorticoids

-Thyroid hormones: T3 T4

 

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