Lecture 3- Principles Of Hormone Action Flashcards
Endocrine
Act on cells distant from the site of secretion
How are endocrine hormones released?
Into the blood stream by ductless endocrine glands
What are the 2 major forms of diabetes mellitus?
- Insulin dependent diabetes mellitus
2. Non insulin dependent diabetes mellitus
Which of the 2 types of diabetes mellitus is commonly referred to as type 1?
Insulin dependent diabetes mellitus
When does type 1 diabetes normally occur?
Childhood
When does type 2 diabetes usually occur?
After the age of 40
Where is insulin secreted from?
Beta cells of the islet of Langerhans
What is the first thing that happens after insulin binds to the receptor?
Endocytosis
What does endocytosis of the insulin receptor complex lead to?
Degradation of the hormone and regulation of the receptor numbers
When is the number of insulin receptors down-regulated?
When the insulin plasma concentration is high
Why is the insulin receptor down regulated at high insulin plasma concentrations?
Because of the accelerated rate of endocytosis and degradation
Why does the target cell lose sensitivity to insulin?
Synthesis of new receptors is slower than the degradation of those bound to insulin
Paracrine
Act on cells close to the cell that released the hormone
How do local mediators differ from neurotransmitters?
Local mediators are releases in a non directional manner into the extracellular space, instead of synaptic cleft
Prostaglandins, histamines and peptide growth factors are examples of which hormone class?
Paracrine hormones
Which cells release histamine?
Mast cells
When do mast cells release histamine?
When activated at the site of injury or infection
What is the major effect of histamine?
Causes blood vessels to be leaky
What are the cardinal signs of inflammation that occur due to histamine actions?
Redness, swelling, pain
What is the benefit of the effects of histamine?
The ‘leaky’ blood vessels allow immune system cells to gain access to the site of infection
Autocrine
Act on the same cell that released the hormone
What hormone is released by T-cells which then stimulates T cell proliferation?
interleukin-2
T cell binding to a macrophage with an antigen induces what process in the T cell?
Clonal selection
What T cell secretion enhances clonal selection?
Interleukin-2
When do T cells express IL-2 receptors?
While bound to a macrophage
What is the effect of human growth hormone on fat cells?
Breaks down triglycerides and inhibition of lipid uptake
What hormone is secreted from the liver in response to human growth hormone?
Insulin like growth factor (IGF-1)
What is the name of insulin’s precursor?
Proinsulin
What part of proinsulin is cleaved to form active insulin?
C chain
Steroid hormones are all derived from what molecule?
Cholesterol
Where is progesterone synthesised?
Corpus luteum
What glucose related process do glucocorticoids stimulate?
Gluconeogenesis
What process do mineralcorticoids stimulate in the kidney?
Sodium re-uptake
Which hormone type is lipid soluble?
Steroid hormones
Where are the receptors for lipid soluble hormones?
Within the target cell
What are the receptor molecules for steroid hormones?
Transcription factors
