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63 Cards in this Set

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  • Back
What are the 4 types of classical hormones?
-Tyrosine derivatives
What makes peptides different from proteins?
Peptides have <20 AA

Proteins have >20 AA
What are the 5 Tyrosine derivative hormones?
1. Epinephrine
2. Norepinephrine
3. Dopamine
4. Triiodothyronine
5. Thyroxine
What are the 6 Steroid hormones?
Vitamin D
What are the 8 Peptide hormones?
Vasopressin (ADH)
Melanocyte-stimulating hormone
Thyrotropin releasing hormone
Gonadotropin releasing hormone
What are the protein hormones?
Insulin, Glucagon, ACTH, TSH, FSH, LH, GH, Prl, CRH, GHRH, PTH, CCK, Secretin,
Chorionic gonadotropin,
What is an Endocrine substance?
A Substance released by ductless glands and transported via the blood to exert its effect on a target tissue other than that from whence it came.
What is a Neuroendocrine substance?
One that is released from nerves
What is a Paracrine substance?
One that acts on a different cell type than the one that released it, but in the same tissue.
What is an Autocrine substance?
One that is released by a cell and acts on that same cell.
What does the chemical nature of a hormone or endocrine substance determine?
Specificity - what receptor the substance will bind.
What hormones have the highest percent of protein binding?
Thyroxine T4 and Triiodothyronine T3
What hormones has the longest half life and lowest metabolic clearance? What are intermediate?
Highest protein bound:
T4 > T3 (both almost 100%)

Cortisol .94
Testosterone .89
Aldosterone .15
What does long half life and low metabolic clearance indicate?
That the substance is highly bound by plasma proteins, hence protected from metabolism or clearance.
What 3 hormones are bound to nil protein and degraded quickly?
-Growth hormone
(all proteins)
Why do we care how much hormone is free vs protein-bound?
Because it's the free hormone that is biologically active.
If a hormone is not ever bound by plasma proteins what determines its rate of metabolism?
The size - determines how long it takes to chop it up.
Which of the protein hormones is biggest hence has longest 1/2 life?
Thyrotropin = 28,000 mw
Growth hormone = 22,000 mw
Insulin = 6000 mw
3 types of endocrine rhythms:
What is the classic example of a circadian hormone? When does it peak? Trough?
-Peaks in morning (8am)
-Troughs at night (11-12pm)
What is the classic example of an ultraradian hormone? When does it spike?
Gonadotropin Releasing hormone
-Spikes every 90 minutes
What is the classic example of a stimulus-induced hormone?
Prolactin - stimulated by suckling.
Where is Glucagon made?
In the alpha cells of the pancreas
What stimulates/inhibits Glucagon release from alpha cells?
Glucose inhibits Glucagon release
Low glucose stimulates it
What does Glucagon do?
Acts on the liver to cause gluconeogenesis
What is the classic example of a parallel negative feedback loop?
Glucose made by gluconeogenesis will stim Insulin from Bcells & inhibit Glucagon from a-cells, so the liver will stop making more glucose.
What is the first thing necessary for a hormone to be able to act on its target?
The target must express the correct receptor so it can form a Hormone-Receptor Complex.
What happens in general when a hormone binds its receptor?
It activates a cascade so that even small amounts of the hormone will have large effects.
What are 3 locations that a hormone receptor can be?
1. In or on the cell surface
2. In the cell cytoplasm
3. In the cell nucleus
Which hormones generally bind cell surface receptors?
Which hormones generally bind cell cytoplasm receptors?
Steroid hormones
Which hormones generally bind nuclear receptors?
Thyroid hormones
What types of endocrine substances act on Ion Channel-Linked Receptors?
Neurotransmitters like ACh and Norepi
To what receptor type do the majority of hormones bind?
G-protein coupled receptors
What is the business end of the G-protein coupled receptor?
The alpha subunit which is GTP bound in its active form.
What is the Leptin receptor a prime example of?
Enzyme-linked Receptors
What are the 2 components involved in leptin receptor binding?
1. Fast physiological effects via activation of an enzyme cascade
2. Slower effects via activation of STAT proteins.
What is a STAT protein?
Signal Transducer and Activator of Transcription
What type of structure is the leptin receptor?
A homodimer
What is the signal transduction protein that is bound to the intracellular side of the leptin receptor?
What happens when leptin binds its receptor?
1. Phosphorylates Jak2
2. Jak2-Pi phosphorylates STAT3
3. STAT3-Pi activates protein transcription
What cells secrete leptin?
What are the important physiological effects of leptin?
-Regulation of appetite
-Energy balance
What receptor family is the leptin receptor a member of?
The cytokine receptors
What hormones act by using intracellular or nuclear receptors?
Steroids and Thyroid hormones
How do intracellular/nuclear receptors work?
1. Hormone binds receptor
2. Hormone-receptor complex binds HRE - hormone response element
3. Exerts its effect
What is an HRE?
A DNA promotor region
How can hormones alter genetic activity via HREs?
By either activating or inhibiting gene txpn, trnsltn, and protein synthesis
What is the major difference in the result of hormones binding enzyme-linked or cell-surface receptors vs intracellular & intranuclear receptors?
TIMING - it takes a lot longer to see the results of gene manipulation.
What is the predominantly important 2nd msgr to know?
How is cAMP formed?
By a hormone binding its cell surface receptor, activating g-protein a-subunit, which activates Adenylyl Cyclase which converts ATP -> cAMP
What are 2 other important 2nd msgrs?
-PLC breakdown products
What activates phospholipase C?
A g-protein activated by hormone binding its cell receptor
What does PLC do?
Breaks down PIP2 into DAG + IP3
What does DAG do?
Converts inactive Protein Kinase C into Active PKC
What does protein kinase C do?
Phosphorylates proteins to activate them
What does IP3 do?
Makes the ER release Calcium
What is the classic hormone that acts via PLC/PIP2->IP3+DAG?
What is the classic example of a hormone that acts via G-protein coupled generation of a cAMP second messenger?
ACTH and catecholamines
What is the most potent form of Thyroid hormone?
T3 - triiodothyronine
What is the form of thyroid hormone that is released in large amounts?
T4 - thyroxine
What is the direct effect of thyroid hormones on their target cells?
To increase transcription of specific genes in the nucleus
What is the general nature of the protein products of transcription activated by thyroid hormones?
They enhance intracellular metabolic activity in virtually all cells of the body