Endocrine physiology Flashcards
What is the purpose of the endocrine system? (4)
To allow communication in a multi-cellular organism
To allow integration of whole body physiology
To allow rapid adaptive changes to occur
To allow chronic maintenance of metabolism
What are the 3 main types of hormones?
Amine (aa derived)
Peptide
Steroid (lipid/cholesterol derived)
What type of hormone are secreted from the adrenal medulla? Give the main 2 examples of this type
Amine hormones
- Epinephrine
- Norepinephrine
What type of hormone are secreted from the adrenal cortex? Give the main 3 examples of this type
Steroid hormones
- Aldosterone (salt)
- Cortisol (sugar)
- Androgens (sex)
What type of effect/action does epinephrine/norepinephrine secreted from the adrenal medulla have?
Action similar to that of sympathetic nerves
What are steroids derived from?
Cholesterol
True or False: Steroid hormones can not be stored in cells
True, they diffuse lipid bilayers
Why does the removal of circulating steroid/thyroid hormones take longer than that of peptide/amine hormones?
Steroid hormones are water insoluble and are so transported in the blood mainly bound to plasma proteins. Binding prevents the steroids from being excreted/metabolised (cleared from circulation)
How is it that steroid hormones exert their effects? (What is their most common signalling method)
Bind to intercellular receptors that directly alter gene transcription
Define permissiveness
This is when a particular hormone must be present for another hormone to be able to exert its full effects
Define the term ‘tropic’ hormone
A hormone that stimulates the secretion of another hormone
Type 2 diabetes mellitus is an example of which type of endocrine disorder: hyposecretion, hypersection, hyporesponsiveness, hyperresponsiveness
Hyporesponsiveness: cells don’t respond to insulin
What is meant by a portal system?
Vein between two capillary beds
Define the term hormone
A signalling molecule secreted from specialised endocrine tissue
From which embryological layer is the adrenal cortex derived from?
Mesoderm