Hormones and Receptors Flashcards
What are the major endocrine glands in the body?
Thyroid and parathyroid Pancreas Hypothalamus and pitutary gland adrenal glands ovaries/testes placenta in pregnant female
What does “paracrine” mean?
specialised cells releases substance and act locally to adjacent cells
What does “autocrine” mean?
cells release chemical substance which has effect limited to the cell which released it – numerous white blood cells use this
List the chemical classes of hormone
Glucoproteins and peptides
Steroids
Tyrosin and trytophan derivatives (amines)
Describe the general idea of the endocrine system
Communication between glands and other tissues achieved by the secretion of a hormone into the blood stream and transport to a target site.
Glands are anatomically distinct but form a functional system.
How is specificity of signalling achieved?
- chemically distinc hormones
- specific receptors for each hormone
- distinct distribution of receptors across target cells
What are the 6 overall functions of the endocrine system?
- regulation of nutrient metabolism, H20 and electrolyte balance
- enabling changes to stress
- promoting growth and development
- conrolling reproduction
- regulating red blood cell production
- controlling and integrating the activites of the cardiovascular and digestive systems
In terms of synthesis, storage, release and transport what happens to amine hormones?
pre-synthesised, stored in vesicles
released in response to increased intracellular Ca2+ - Ca2+ dependent exocytosis
hydrophilic - transported mainly free in plasma
In terms of synthesis, storage, release and transport what happens to peptides and proteins hormones?
pre-synthesised (usually from a longer precursor) stored in vesicles
released in response to increased intracellular Ca2+ - Ca2+ dependent exocytosis
hydrophilic - transported mainly free in plasma
What synthesises the precursor protein in peptide and protein hormone synthesis?
Rough ER
In terms of synthesis, storage, release and transport what happens to peptides and proteins hormones?
Synthesised and secreted on demand (not stored in vesicles!)
Hydrophobic and transported in plasma mainly bound (~90%) to plasma proteins - only “free” is biologicaly active
What are all steroid hormones derived from?
Cholesterol
What is the purpose of carrier proteins?
- increase amount transported in blood
- prevent rapid excretion by filtration at the kidney
Give some exaples of important general carrier proteins.
Albumin and transthyretin
Name 3 importat specific carrier proteins.
Cortisol-binding globulin
Thyroxine-binding globulin
Sex steroid- binding globulin
Give another function of circulating carrier proteins?
Act as a buffer and reervoir that helps to maintain relatively constant concentrations of free lipophiic hormone in the blood - free and bound hormone are in equilibrium
What are the 3 methods of control of hormonal levels?
- negative feedback
- neuroendocrine (elicits a sudden burst in secretion to meet a specfic stimulus)
- diurnal rhythm
What are the 3 groups of hormone receptors?
GPCR
Receptor kinases
Nuclear receptors (3 classes)
Of the 3 types of hormone receptor, which one is the odd one out and why?
Nuclear receptors - they are intracellular receptors whereas GPCR and receptor kinases are cell surface receptors
Which class of nuclear receptors is when unbound, found in the cytoplasm bound to inhibitory heat shock protein?
Class 1
Which class of nuclear receptors does thyroiod hormone bind to?
Hybrid class
