What is the primary aim of the endocrine system?
To maintain a stable and balanced internal environment
What type of signalling molecules does the nervous system use?
Neurotransmitters
What type of signalling molecules does the endocrine system use?
Hormones
Where do exocrine glands secrete their porducts?
Into ducts, then expelled on the outside of the body
Do exocrine secrete hormones?
No they do not
Where do signalling molecules bind?
Onto target cells to initiate a response
How do hormones travel in the body?
Through the blood
Where are the protein receptor cells located?
Embedded in the membrane or the cytoplasm of the cell
What happens once a cell is activated?
It develops and acts in certain ways based on the signals transmitted by the hormone
What are the three pain pathways for action for hormones?
Travel in blood (endocrines), act on neighboring cells (paracrines), act on the same cells that secreted them (autocrines)
What kind of hormones circulate in the blood with the help of transport proteins?
Lipid-soluble
Where do lipid-soluble hormones bind?
To receptors within target cells
What kind of hormones circulate freely in the blood plasma?
Water-soluble
Where do water-soluble hormones bind?
To the exterior surface of the targe cell
How do water-soluble hormones make a response?
They activate a secondary messenger response (phosphorilation)
What two basic actions can phosphorylation cause?
Activation (excitatory) or inactivation (inhibitory)
What does it mean when a cell is up-regulated?
Receptors become more sensitive to the presence of low concentrations of hormone
What does it mean when a cell is downregulated?
Receptors become less sensitive in the presence of high concentration of hormone
What are the 3 factors that influence the response of a target cell to a hormone?
- The hormones concentration in the blood
- The number of hormone receptors on the target cell
- Influences exerted by other hormones (synergistic/antagonistic)
What are the 3 factors that influence hormone secretion?
- Chemical changes in the blood
- Signals from the nervous system
- Other hormones
What does the endocrine system typically rely on to regulate hormone production and secretion?
Feedback systems, usually negative feedback, though positive feedback systems are sometimes used
How are the nervous system and endocrine system linked?
The hypothalamus, 7 hormones released by the hypothalamus tell the pituitary gland which hormones to release
What are the 5 releasing hormones in the hypothalamus?
TRH, CRH, GnRH, PRH, GHRH
What are the 2 inhibiting hormones from the hypothalamus?
GHIH, PIH
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