Lecture 57- Hormone Synthesis, Regultion Of Hormone Secretion, And Hormone Receptors Flashcards
What does the endocrine system work together with to maintain homeostasis?
Nervous system
What does the endocrine system regulate?
Growth, development, reproduction, blood pressure, ion concentration, behavior, aging
What is the definition of hormone?
Chemical secreted into circulation in small amounts, delivered to target tissue … tissues then respond
Where are most hormones synthesized in, and secreted by?
What are the exceptions?
Glands
Exceptions: GIT hormones secreted by clusters of endocrine cells, some made in hypothalamus, placenta, kidney
What are common characteristics of endocrine cells and neurons?
-both secrete substances into blood
-some molecules are BOTH neurotransmitters and hormones
-mechanisms of action for hormones and neurotransmitters require a specific receptor
-similar processes of exocytosis of granules and synaptic vesicles
(TRUE/FALSE) Both endocrine cells and neurons response to the same stimuli
TRUE
What is homeostasis?
Ability of body to maintain a stable internal environment despite changes in external condition
What are 3 mechanisms to restore and maintain a homeostasis?
Receptor
Control Center
Effector
What are negative feedback loops? What are they absolutely essential to?
Negative feedback loop: system responds in a way to reverse direction of change
Essential to homeostasis
(TRUE/FALSE) Positive feedback results in homeostasis
FALSE
Positive feedback does not result in homeostasis
*amplifies change in variable— blood clotting, parturition
What are pathways that alter homeostasis?
Nutrition, toxins, psychological, physical, genetic, medical
What are four hormone signaling pathways?
- Endocrine/Telecrine
- Neurocrine
- Autocrine
- Paracrine
Describe the endocrine/telecrine hormone signaling pathway?
Travel a long distance in blood to target tissue
Describe the neurocrine hormone signaling pathway?
Secreted by neurons into blood
describe the Autocrine hormone signaling pathway?
Exerts effects on itself or very close identical cells
Describe the paracrine hormone signaling pathway?
Close to target cells, usually through within same tissue, diffusing through interstitial fluid
What is the structure of peptides and proteins?
Structure varies across species (growth hormone)
Amino Acid
What is the structure of steroids?
-structure usually conserved across species
-cholesterol used to synthesize
What is the structure of Amines?
-derived from tyrosine
What is the structure of Eicosanoids?
-derived from fatty acids
Why can growth factor hormones act on insulin receptors?
Because structure is very similar
What are the steps in synthesis?
- MRNa is transcribed and travels to cytoplasm
- Message is translated on ribosome
- Product is preprohormone—now transferred to ER
- Signal peptide degraded in ER—resulted in prohormone, now transferred to Golgi
- When endocrine cell stimulated, granule contents released
(TRUE/FASLE) A stimulus always results in immediate release
FALSE
Transcription and translation are needed, so a stimulus does not always result in immediate release.
What are catecholamines synthesized using?
Tyrosine
What are thyroid hormones synthesized from?
Tyrosine and iodide
Where are thyroid hormones stored?
In a follicle — thyroglobulin
*secretion requires retrieval follicles and release from storage protein
Where are steroid hormones synthesized?
Cholesterol
*not usually stored, secretion requires synthesis
Where are prostaglandins synthesized?
Arachidonic acid
What are the two mechanisms of regulation of hormone secretion?
- Neural mechanisms
- Feedback mechanisms
State the differences between long, short, and ultra short feedback loops.
Long loops- hormone released from target tissue funds back to original release point (pituitary or hypothalamus)
Short loop- negative feedback from pituitary to hypothalamus
Ultra short- hypothalamic hormone inhibiting its own secretion
What is positive feedback?
A feature of hormone action causes MORE secretion of the hormone
