Endocrine Review

Question 1

How is reproduction regulated?

Answer 1

Endocrine and nervous system

Question 2

Classical endocrine signalling

Answer 2

Hormones are synthesized by endocrine glands, secreted into blood and carried to target tissues that are some distance from glands

Question 3

Neuroendocrine system

Answer 3

Neutron produces neurohormone - bloodstream - target

Question 4

Autocrine regulation

Answer 4

Cell produces hormone that diffuses in interstitial fluid and acts on self

Question 5

Paracrine regulation

Answer 5

Cell releases hormone into interstitial fluid that acts on nearby target cell

Question 6

Neuroendocrine signalling

Answer 6

Neuron produces neurohormone - directly acts on target cell

Question 7

Synthesis

Answer 7

Depends on availability of substrate and cell machinery for synthesis/conversion, and stimulus for hormone production

Question 8

Secretion

Answer 8

Varies in pattern and duration, regulates by feedback

Question 9

Episodic Secretion

Answer 9

Hormone released in bursts, varies in frequency and quantity

Question 10

Basal secretion

Answer 10

Hormone remains at a low level and has minimal fluctuations

Question 11

Sustained secretion

Answer 11

Steady secretion for extended period of time

Question 12

Transport

Answer 12

To target tissue determined by structure, solubility in plasma, and availability of carriers

-steroids and eicosanoids are lipid soluble and need carrier proteins to reach target

Question 13

Cell Membrane Receptor

Answer 13

Extra cellular, transmembrane and intracellular domains

• when bound to extracellular, induce conformational changes

Question 14

Nuclear Receptors

Answer 14

Within cell, bind to lipid-soluble hormones that can diffuse across cell membrane

• bind to response elements of DNA to affect transcription
• slow response (hours to days)

Question 15

Receptor Density

Answer 15

Varies depending on cell type and stimulation, can be up/down regulated by duration of exposure omits hormone

• greater affinity = greater biological response

Question 16

Agonists/analogs

Answer 16

Similar structure and action as native hormone (original), bind receptor with similar or greater activity

Question 17

Antagonist

Answer 17

Interfere with original hormone action, bind to receptor with greater affinity that native hormone and promotes weaker biological activity

Question 18

Rate of Hormone Clearance

Answer 18

Determines hormone half-life, depending on binding proteins, glycosylation, and host metabolism

-high metabolic rate = high rate of clearance
- protein bound cleared lower due to affinity for carriers

Question 19

Protein Hormone Metabolism

Answer 19

Deglycosylated or denatured, bound to hepatocytes, internalized, and degraded in cytoplasm; AA recycled

Question 20

Eicosanoids

Answer 20

Rapidly degraded in blood after one pass through pulmonary circulation

Question 21

Steroids

Answer 21

Liver deactivates them by saturating double bonds, and makes then hydrophilic by adding sulphates or glucuronide residues

• then excreted through blood into urine or bile into feces