9.0 Endocrine

Question 1

what are the 3 classes for hormones?

Answer 1

hormone = chemical released by a cell in one part of the body that affects cells in antoher part

endocrine: hormones secreted directly into blodo stream

Neuroendocrine: hormones produced by neurons secreted into blodostream

exocrine: hormones are secreted directly into a duct (can enter blood stream)

Question 2

qutocrine vs paracrine

Answer 2

autocrine: chemicals that exert effects on same cells

ex: cytokine interleukin-1 from monocytes

Paracrine: locally acting chemicals that affect nearby cells

-> responses to allergens, tissue repair, formation of scar tissue and blood clotting

*peptides are not considered hormones, hormones are long distnaced chemical signals

Question 3

two mechanisms of hormones

Answer 3

• *Second messengers -** Regulatory G proteins tend to be amino acid-based hormones
• *Direct gene activation** - Tend to be steroid hormones

Question 4

what are the actions of hormones (cellular changes to target cells)?

Answer 4

Alter plasma membrane permeability

Stimulate protein synthesis
Activate or deactivate enzyme systems

Induce secretory activity

Stimulate mitosis (growth)

Question 5

hwo does target specificity relate to hormone activity

Answer 5

• target cells must ahve specific receptors to which the hormone binds

ACTH receptors: found on certain cells of adrenal cortex

Thyroxin receptors found on nearly all cells of body

Question 6

what factors influence target cell activation

Answer 6

1. Blood levels of the hormone
2. Relative number of receptors on the target cell
3. The affinity of those receptors for the hormone

Question 7

how do hormones circulate in the blood? what are their concentrations influenced by?

Answer 7

• circulate as free or bound
• > sterior and thyroid bound to plasma proteins
• > most of rest are free

Concentration of circulation hormoens dep on: rate of release, speed of inactivation, removal from body

Question 8

hormones are removed by …

Answer 8

Degrading enzymes

The kidneys and liver enzymes

Question 9

half lives of hormoens

Answer 9

thyori longers (days)

steriods some of shortest (4-120 min)

Question 10

what are the 3 types of interactions of hormones at target cells

Answer 10

• permissiveness
  
  • ​one hormone cant act without another hormone being present
• Synergism
  
  • ​more than one hormone produces the same effects on a target cell
• Antagonism
  
  • ​one or more hormones oposes the action of another hormone (insulin and glucagon, dopamine and prolactin)

Question 11

how is hormone release controlled

Answer 11

• by blood levels: negative feedbck, vary only in a narrow desirable range
• Synthesized and released in response to: Hormonal stimuli, neural stimuli, humoral stim

Question 12

How does humoral stimuli influence hormone release

Answer 12

• secretions of hormones in direct response to changing blood levels of ions and nutrients
  ex: concentration of calcium ions in blood (reg release of parathyroid formone)

Question 13

How does neural stimuli influence hormone release

Answer 13

• nerve fibers stim hormone release
• innervation thoruhg spinal chord
  ex: preganglioninc SNS fibers stimulate adrenal medulla cells to release catecholamines

Question 14

How does hormonal stimuli influence hormone release

Answer 14

• from tropic hormones: one hormone that alters the release of another
• tropic hormones secreted by hypothalamus to stim anterior pituitary galnd to secrete hormones that stimulate other endocrine glands

Question 15

What are teh 3 types of hormones

Answer 15

1. Eicosanoids: leukotrienes and prstaglandind (not a true hormone, more autocrine and paracrine function)
2. Amino acid based; amines, thyroxine, peptides and protein hormones
3. Steroids: gonadal and adrenocortical

Question 16

describe eicosanoids (duration, types of activity and examples)

Answer 16

• short lives (sec=min) biologically active lipids
• autocrine and paracrine activity
  ex: Prostaglandin: inflammation, fever production, prevent platelet aggregation (prevent clotting), induce labour)
  ex: thromboxanes: produced by platelets to promtoe their aggregation (blood clotting)
  ex: leukotrienes: llergic rxns

Question 17

what are eicosanoids derivded from

Answer 17

• derives from arachidonic acid (AA, found in PM)
• produced from alpha linolenic acid (omega 3 FA) and linoleic acid (omega 6 FA)

Question 18

why are eicosanoids relevant for therapeutics

Answer 18

• form thomboxanes in platelets and prostaglandins in cells
• > pathway of NSAIDs

Question 19

describe the eicosanoid pathway

Answer 19

• formation of prostaglandins: induce labour, vasodilation, pain, pyretic
• formation of prostacylcins: inhibit platelet aggregation, vasodilation
• free arachidonic acid converted to PGG via COX-1 and COX-2
• can inhibt COX2 w/ VIOXX

Question 20

describe the leukotriene pathway

Answer 20

conversation of arachidonic acid to LTE (involves in asthma inflammation) and LTB (extravascularization

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