General Endorinology Flashcards
What is a hormone
Chemical substance
Sythesised and secreted by a specific gland
Secreted in small amounts into the blood stream
Acts at a site distant from the site of secretion
Acts on specific receptors to give a specific physiological effect
Where are horomones produced
Synthesised and excreted by the gland specific to the particular hormone
How do hormones travel round the body
In the blood stream
How far do hormones have to travel
They act on areas that are far away from the site of secretion
How to hormones cause effects
By binding to their specific receptor
What things do hormones regulate
Reproduction
Growth and development
Maintenance of the internal environment
Regulation of digestion and energy availability
Types of hormones
Proteins
Peptides
Amino acid derivatives
Lipids and steroids
What hormones are soluable in water
Peptide hormones
Protein hormones
Catecholamines
Examples of amino acid derivated hormones
Thyroid hormones
Catecholamines
Melatonin
Hormones that are lipid soluable
Steroid hormones
Thyroid hormones
How do hormones act on target cells
Act on specific receptors
Regulate the activity of the cell
Mechanism of action depends on the hormone
Hormones that do not enter the cell
Peptide
Protein
Catecholamines
How hormones that do not enter the cell work
Bind to cell surface receptors
Activate or inhibit intracellular signalling pathways
This alters protein and enzyme activities
The cascade effect in hormones
Hormones secreted in small quantities
Receptor mechanisms cause amplification
Activated proteins in turn activated other proteins in greater number
Hormones that do enter the cell
Lipid soluable ones:
- Steroid hormones
- Thyroid hormones
What guides hormones that enter the cell to the nucleus?
Cytoplasmic and/or nuclear receptors
How are hormones controlled
Neural regulation
Endocrin and neuroendocrine regulation
Non-neural/non-endocrine regulation
Positve and negative feedback
Other aspects of hormone bioavailability
Other aspects of bioavailability that control hormones
Substrate availability
Hormone metabolism (activating and inactivating enzymes)
Binding proteins in the circulation and tissues
Access to target tissues
Tissue sensitivity
Hormones that are stored after secretion
Peptide
Protein
Catecholamines
Hormones that are produced in response to stimulus and not stored
Steroid hormones
Thyroid hormones
What hormones don’t travel in the blood with binding proteins
Peptide
Protein
Catecholamines
What hormones travel in the blood with binding proteins
Steroid hormones
Thyroid hormones
Which hormones are broken down by proteases and cell lysosomes
Peptide
Protein
Catecholamines
Which hormones are modified by the liver so they’re water soluable
How are they then excreted
Steroid and thyroid hormones
Excreted in bile/urine
Which hormones have a half-life of minutes
Peptide
Protein
Catecholamines
Which hormones have a half-life of hours
Steroid hormones
Thyroid hormones
What hormones have a rapid onset and short duration
Protein
Petide
Catecholamines
What hormones take a while to cause an effect but have a long duration
Steroid hormones
Thyroid hormones
Which hormones may have a permanent effect
Steroid hormones
Thyroid hormones
