Diabetes and Endocrinology Flashcards
Define endocrine communication
Hormones will travel through the blood until they reach a target cell which has a receptor for that specific hormone (No receptor = no response)
Define neuro-endocrine communication
The release of neuro-homrones from the posterior pituitary gland which travel directly into the blood to target organs which have a receptor for that hormone
What is the purpose of a hormone binding to a cell receptor
To alter the activity within that cell
Where are the receptors for peptide hormones found?
On the cell surface
What are autocrine signals?
Where cells secrete chemicals which bind to their own cell
What are paracrine signals?
Where chemicals diffuse within the ECF to bind to a neighboring cell
What are peptide hormone comprised of?
Chains of amino acids
Which kind of hormone is the most common?
Peptide hormones
What are peptide hormones synthesised as in advance of their requirement and then what are they cleaved into?
preprohormone
Prohormone
In what form are peptide hormones stored as?
Prohormone
What is released into the blood alongside the peptide hormones and why is this clinically useful?
Peptide fragments
Inactive fragments (C-peptide) can be measured clinically
Why is C-peptide measured within the body and what is it ?
An inactive peptide fragments
Insulin is metabolized faster than C-peptide therefore it is easier to measure
What is the fastest channel found om the cell surface?
Ion channels
What 2 kind of cell surface receptors are found to be areas where peptide hormones bind?
G-coupled channels
Tyrosine kinase receptors
When a peptide hormone binds to the cell surface receptors what occurs within the cell?
2nd messenger system is activated which opens the ion channel
Altering of gene expression
What are the majority of amine hormones derived from?
Tyrosine
What is melatonin derived from?
Tryptophan
What are steroid hormones derived from?
Cholesterol
What kind of hormones arent stored and why ?
Steroid hormones, lipophillic nature would cause them to diffuse out of the cell
How do steroid hormones travel through the blood stream?
Steroid hormones must be bound to a carrier protein in order to travel through the blood i.e. Albumin.
This also prevents them from degradation and increases their half-life (longer duration of action)
What tissues produce steroid hormones?
Gonads (Testes and ovaries)
Adrenal cortex (Corticosteroids)
Placenta (HCG and sex steroids)
Kidney (Vitamin D3)
Where are the cell receptors for steroid hormones found?
Within the cell
Which are faster cell surface or intracellular receptors ?
Cell surface receptors
in order for a steroid hormone to pass the cell surface it needs to be ________
Unbound
