Final: Animal Hormones Slides Flashcards
(46 cards)
Endocrine system structure and function
Major communication system, consists of many glands located throughout body
What do glands do?
Release hormones that act as chemical messengers
How do hormones get to their target cell(s)?
Use the blood as a medium of transport (long distance travel)
Difference between major and mixed/secondary/accessory glands
Only function of major glands is to release hormones; mixed glands release hormones but have other functions
Name the major glands (8)
Hypothalamus, pineal, pituitary, thyroid, parathyroid, adrenal glands, pancreas, gonads
Name the minor glands (5)
Thymus, heart, stomach, kidneys, small intestine
What does a receiving cell need to respond to a hormone?
the right (matching) receptor
Main chemical (structural) difference between peptides and steroids
Peptides: amino acid sequences; large; cannot permeate into cell
Steroids: modified from cholesterol; can permeate into cell
Receptor location for peptides and steroids
Extracellular for peptides (on cell membrane), Intracellular for steroids (inside cell)
How are peptides and steroids synthesized?
Peptides made in rough ER, ribosomes, and Golgi
Steroids made in smooth ER and mitochondria
How are peptides and steroids secreted?
Peptides secreted by exocytosis
Steroids secreted by simple diffusion (they’re lipophilic so can cross the membrane)
Steps in peptide synthesis
- Start as preprohormones in ribosomes and RER
- Get converted to prohormones (packaged in Golgi as prohormones)
- Become actual active hormones once released
How do peptides and steroids travel in the blood?
Blood is mostly water: Peptides don’t need carrier protein but steroids do (bc lipids don’t mix with water)
What is the third class of hormones?
Amines, which are modified single amino acids
Mechanisms of steroid action on target cell(s)
Binds to receptor inside cell (could be in nucleus or cytoplasm) - hormone receptor complex binds to DNA on HRE - activates/deactivates genes - affects mRNA and then protein synthesis - physiological response
What is the hormone response element (HRE)?
Binding site for hormone receptor complex on DNA
Mechanisms of peptide action on target cell(s)
Bind to extracellular receptor - activate G protein - activate adenylyl cyclase and cAMP synthesis - start protein kinase cascade - brings about cellular response
Main difference in effect of steroids and peptides
Peptides are faster than steroids bc they mostly activate local responses in local proteins, but steroids cause major changes bc they mess with DNA
Mechanisms of hormonal secretion
Humoral, neural, hormonal
How does the humoral mechanism work? Give an example.
Measures some factor in the blood
Example: always need homeostatic level of Ca2+ - what if calcium levels are low?
-Receptor and control center: parathyroid gland
-Parathyroid gland releases parathyroid hormone (PTH) to restore calcium levels to normal (Ca2+ comes from bones)
How does the neural mechanism work? Give an example.
Controlled by nervous system
Example: Input from sympathetic NS causes release of epinephrine (amine) from adrenal medulla (in adrenal gland); has lots of target cells
How does the hormonal mechanism work?
Gland releases hormone A, which triggers release of hormone B, and so on until response achieved
Another name for the hypophysis
Pituitary gland
Importance of hypophysis
Produces 8 hormones that are essential to survival
