PHTY208 Lecture Notes - Lecture 18: Vasomotor, Polyphagia, Coronary Artery Disease
Diabetes Mellitus and the metabolic syndrome:!
Introduction:!
-A group of metabolic disease in which a person’s high blood glucose !
-Approx. 7% of the population currently have type 2 diabetes but more common in Indigenous
Australians (20%)!
-The most common types of diabetes are:!
-Type 1 diabetes: results from the body’s failure to produce insulin!
-Type 2 diabetes: results from insulin resistance, a condition in which cells fail to use insulin
properly !
Concept 1: Hormonal control of glucose, fat and protein metabolism:!
Glucose, Fats and Protein:!
-The body uses glucose, fats and proteins as major energy sources for the body !
-The liver, with hormones from the pancreas, regulates energy production!
-Glucose is metabolised to CO2 and H2O !
-Fat is metabolised to glycerol and fatty acids!
-Protein is metabolised to amino acids!
Tissue types and functions of the pancreas:!
-Acini - secrete digestive juices into the duodenum!
-Islets of langerhans!
-Secrete hormones into the blood, beta cells that secrete insulin and amylin, alpha cells that
secrete glucagon , delta cells that secrete somatostatin !
Actions of Insulin:!
-Central to regulating carbohydrate and fat metabolism in the body, promotes conversion of
triglycerides to fat and subsequent storage in adipose tissue, promotes glucose uptake by
insulin sensitive target cells in muscle and liver, provides for glucose storage as glycogen, ^
glycogen synthesis, inhibits hepatic gluconeogenesis, ^ protein synthesis !
Actions of Glucagon:!
-Opposite of insulin, catabolic in nature, ^ transport of amino acids into hepatic cells , promotes
glycogen breakdown, ^ breakdown of proteins into amino acids for use in gluconeogensis, ^
conversion of amino acids into glucose precursors !
Other hormone affecting blood glucose:!
-Catecholamines- epinephrine and norepinephrine, help to maintain blood glucose levels during
periods of stress!
-Growth hormone- ^ protein synthesis in all cells of the body, mobilises fatty acids from adipose
tissue, and antagonises the effects of insulin!
-Glucorticoids - critical to survival during periods of fasting and starvation, stimulate
gluconeogensis by the liver !
Diabetes:!
Diabetes Mellitus:!
-Disorder of carbohydrate, protein, and fat metabolism!
-Results from an imbalance between insulin availability and insulin need!
-Can represent:!
-An absolute insulin deficiency, impaired release of insulin by the pancreatic beta cells,
inadequate of defective insulin receptors, production of inactive insulin or insulin that in
destroyed before it can carry out its action, has a common feature of hyperglycaemia !
Types of diabetes:!
-Prediabetes:!
-Impaired fasting plasma glucose, FPG- 5.6-6.9 mmol/L!
-Impaired glucose tolerance, OGTT- 7.8-11.0 mmol/L!
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-Increased risk of atherosclerotic heart disease and increased risk of progression type 2
diabetes!
-Diabetes:!
-Type 1 results from:!
-Loss of beta cell function, an absolute insulin deficiency!
-Type 1A- immune mediated diabetes!
-Type 1B- idiopathic diabetes!
-Type 2 results from:!
-Impaired ability of the tissues to use insulin!
-A relative lack of insulin or impaired release of insulin in relation to blood glucose levels!
Concept 3: Type 1 diabetes:!
Type 1 diabetes:!
-Characterised by extensive damage to the pancreatic beta islet cells, two main forms, insulin
production and release is reduced, can be insidious or rapid onset, body can compensate and
the condition can go undiagnosed for years!
Development of type 1A diabetes:!
-Genetic predisposition!
-Immunologically mediated beta cell destruction- insulin antibodies or islet antibodies!
-Formerly juvenile diabetes!
-More common in young persons but can occur at any age !
-A hypothetical triggering event involving an environmental agent that incites an immune
response- infection, hypersensitivity reaction, prolonged major stressful event!
-Prone to the development of ketoacidosis- insulin inhibits lipolysis and releases free fatty acids,
without insulin ketosis develops and are converted to ketones in the liver!
Idiopathic type 1B diabetes:!
-Those cases of beta cell destruction in which no evidence of autoimmunity is present!
-Only a small number of people with type 1 diabetes fall into this category!
-Strongly inherited!
-People with the disorder have episodic ketoacidosis due to varying degrees of insulin
deficiency with periods of absolute insulin deficiency that may come and go!
Concept 3: Type 2 Diabetes:!
Type 2 Diabetes:!
-Heterogeneous condition that describes the presence of hyperglycaemia in association with
relative insulin deficiency !
-Peripheral insulin resistance, impaired beta cell function and insulin secretion, ^ hepatic
glucose production!
-Associated with overweight and obese persons!
-Environmental and genetic origins- could be 20 or more genes responsible!
Causes of Beta Cell Dysfunction:!
-An initial decrease in the beta cell mass, ^ beta cell apoptosis/decreased regeneration , long-
standing insulin resistance, leading beta cell exhaustion, chronic hyperglycaemia can induce
beta cell desensitisation (“glucotoxicity”), chronic elevation of free fatty acids can cause toxicity
to beta cells (“lipotoxicity”), amyloid deposition in the
beta cell can cause dysfunction!
Type 2 diabetes:!
-Individuals can have low to normal to high levels of
insulin!
-Peripheral insulin resistance can result in a feedback
mechanismtoincrease production of insulin!
-Hyperinsulinemia !
-^ demands exhaustive beta cell and result in failure or
dysfunction!
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A group of metabolic disease in which a person"s high blood glucose. 7% of the population currently have type 2 diabetes but more common in indigenous. The most common types of diabetes are: Type 1 diabetes: results from the body"s failure to produce insulin. Type 2 diabetes: results from insulin resistance, a condition in which cells fail to use insulin properly. Concept 1: hormonal control of glucose, fat and protein metabolism: The body uses glucose, fats and proteins as major energy sources for the body. The liver, with hormones from the pancreas, regulates energy production. Glucose is metabolised to co2 and h2o. Fat is metabolised to glycerol and fatty acids. Acini - secrete digestive juices into the duodenum. Secrete hormones into the blood, beta cells that secrete insulin and amylin, alpha cells that secrete glucagon , delta cells that secrete somatostatin.
