Chapter 6- Principles of Endocrinology Flashcards
What are the body’s 2 major communication systems?
- Nervous system
- Endocrine system
How do the nervous stem and endocrine system vary in speed?
NS- Rapid
ES- Longer delays, lasts longer
What is the endocrine system?
Ductless endocrine glands scattered throughout the body
Where do endocrine glands secrete into?
Interstitial space then into bloodstream
What do endocrine glands secrete?
Hormones
-Regulate or direct particular functions
What do hormones bind to?
Target cells with specific hormone binding receptors
What controls plasma hormone concentration?
Controlled by changes in rate of hormone secretion
What are tropic hormones?
Released by an endocrine gland and act upon another endocrine gland
How do tropic hormones regulate hormone secretion?
Influence the activity of other endocrine glands
What do tropic hormones stimulate and maintain he function of?
Endocrine target tissues
(Specific tissues affected by tropic hormone)
What kind of control maintains the plasma concentration of a hormone at a given level or set-point?
Negative-feedback
What is a negative feedback control?
Output of a system counteracts a change in input
How is a hormone’s secretion switched off?
It switches off its owns secretion
What is Diurnal rhythm?
24-hour cycles set by the CNS to carry out essential processes.
-Hormone levels vary at times of day
How do hormones influence activity of another hormone at a target cell?
- Permissiveness
2.Synergism - Antagonism
What is permissiveness?
One hormone must be present in adequate amounts for full exertion of another hormone’s effect
What is Synergism?
Occurs when actions of several hormones are complimentary
-Combined effect is greater than the sum of their separate effects
What is Antagonism?
Occurs when one hormone opposes the actions of another hormone
What most commonly causes endocrine dysfunction?
Inappropriate rates of secretion
What are types of inapropriate rates of secretion?
a. Hyposecretion (too little hormone secreted)
b.Hypersecretion (too much hormone secreted)
What are the 3 groups of hormones based on chemical nature?
- Peptides and proteins
- Steroids
- Amines
What is the chemical nature of peptide and protein hormones?
Hydrophilic
What is the chemical nature of steroid hormones?
Lipophilic
What is the chemical nature of Amine hormones?
Lipid/water solubility depends on hormone
What are peptide and protein hormones?
Most common
Are synthesised, processed and packaged before being secreted
What are steroid hormones?
Hormones derived by cholesterol from in cell stores that are modified by enzymes
What does the final product of a steroid hormone depend on?
Cell type
e.g testosterone converted to estradiol in ovaries
Can steroid hormones be stored?
No
What is an example of a steroid hormone?
Aldosterone
-Secreted by cells in the adrenal cortex
What are amine hormones?
Derived from amino acids
Examples of amines?
- Thyroid hormones
- Melatonin
3.Catecholamines
What amino acids are thyroid hormones derived from?
2 tyrosines
What amino acid is melatonin derived from?
Tryptophan
What gland secretes melatonin?
Pineal gland
What gland secretes catecholamines?
Adrenal glands
What is the chemical structure of a catecholamine?
Catechol group + amine group