Introduction to endocrinology Flashcards
What is endocrinology?
The study of biosynthesis, secretion, regulation and action of hormones as well as glands and tissues that produce them
What is a hormone?
A chemical substance formed in glands that is carried in the bloodstream to affect another part of the body
What is an endocrine organ?
Glands that secrete their products (hormones) directly into the bloodstream rather than through a duct (exocrine)
Name 3 hormone groups
1) Amine
2) Peptide
3) Steroid
Define amines and list examples
Are derived from a single amino acid
Epinephrine/norepinephrine/dopamine (tyrosine)
Define peptides and list examples
Peptides are derived from multiple amino acids (3-200)
They are all pituitary hormones
Insulin/leptin/ghrelin
Define steroids and list examples
Steroids are derived from cholesterol
glucocorticoids/mineralcorticoids/androgens/progesterone
Describe the function of the pituitary gland
Endocrine ‘master gland’
crucial connection between the endocrine and nervous system
consists of anterior and posterior lobes
List 5 hormones that are produced by the anterior lobe of the pituitary gland
Adrenocoticotrophic hormone (ACTH) Thyroid stimulating hormone (TSH) Follicle and luteinising stimulation hormone (FSH/LH) Growth hormone (GH) Prolactin
Which hormones are secreted by the thyroid gland?
Thyroxine (T4) and triiodothyronine (T3) are produced by iodination of thyroglobulin in response to TSH from the anterior pituitary
What is the function of thyrorid hormones?
To regulate body metabolism and ensure healthy cellular development
List common disorders of the thyroid
Hyperthyroidism
Hypothyroidism
Adenoma/goitre
Cancer
How are the adrenal glands regulated?
Through the ACTH and renin-angiotensin system
Which hormones are produced by the adrenal cortex?
Corticosteroid hormones:
cortisol
aldosterone
androgens
Which hormones are produced by the adrenal medulla
Catecholamines:
Epinephrine
Norepinephrine
Dopamine
List the main disorders of the adrenal glands
Insufficiency - Addison’s
Excess activity - Cushing’s, primary aldosteronism, phaeochromocytoma
What are the gonads
Sex organs - testes and ovaries
What are the functions of testes
Leydig cells are a source of testosterone in response to LH
Spermatogenesis occurs in Sertoli cells in response to FSH
Also produces other androgens (androstenedione)
What are the functions of ovaries
Source of oestrogen and androgen
regulated by FSH/LH
Describe the endocrine pancreas briefly including the hormones secreted
consists of islet of langerhans Insulin is secreted by beta cells Glucagon is secreted by alpha cells Somatostatin is secreted by delta cells Pancreatic polypeptide is secreted by PP cells
Hormones are secreted into the capillaries
Decribe the exocrine pancreas
Consists of centroacinar cells that secrete proteases, lipase and amylase.
Secretions are controlled by hormones from the stomach and duodenum.
The pancreatic duct epithelium secretes bicarbonate
Describe the action of steroids/ thryroid hormones
Bind to intracellular receptors
The receptor/ligand complex binds DNA to affect transcription
Describe the action of G protein coupled receptors
G proteins initiate cellular changes by acting directly on processes (such as ion channels) or through second messengers, which then affect cell proteins to alter function
Briefly explain homeostasis in endocrinology
To maintain a physiological parameter within a narrow range of values (e.g. blood glucose concentration), that is perceived by tissues
This leads to a signal from the target organ to communicate to other tissues that can then act to stabilise that parameter
E.g.
Briefly explain homeostasis in endocrinology
To maintain a physiological parameter within a narrow range of values (e.g. blood glucose concentration), that is perceived by tissues
This leads to a signal from the target organ to communicate to other tissues that can then act to stabilise that parameter
E.g. simple molecules (O2)
ion currents
other hormones (insulin, steroids)
Describe different responses to signals
Positive feedback - amplifying the change
Negative feedback - resisting the change
Feed forward - anticipation of change
Complex processes may have several feedback loops
What is the difference between T1DM and T2DM
T1DM is autoimmune and affects 12% of the diabetic population
T2DM includes obesity as a major factor and affects 88% of the population
List 3 microvascular complications of DM
Dependent on glycaemic control
- retinopathy
- nephropathy
- neuropathy
List 2 macrovascular complications of DM
Dependent on other risk factors
- coronary heart disease equivalent
- inceased risk of stroke/heart attack
