Lecture 13 Flashcards
Metabolism
sum of all chemical reactions in the body
Anabolic
large molecules synthesized from smaller ones
Catabolic
breakdown of large molecules into smaller ones
Fed State
(absorptive) anabolic, use glucose for energy
Fasted State
(postabsorptive) catabolic, use glucose, and fat for energy
Basal metabolic rate (BMR)
an individual’s energy expenditure when resting, comfortable temperature, fasted
Gluconeogenesis
synthesis of glucose from non-carbohydrate substrates such as glycerol and amino acids
What triggers target cells to change gears between feeding and fasting metabolism
Insulin & glucagon
Glucagon Ratio
Control of glucose homeostasis is monitored by Insulin
Insulin (anabolic)
is the dominant hormone of the fed state
- Synthesized as a typical peptide
- Binds to a receptor tyrosine kinase
- Reduces blood glucose
- Promotes formation of glycogen, fat, and protein
Intrajejunal
within the jejunum (part of the small intestine between the duodenum and ileum)
Incretin effect
The incretin effect is a biological process where eating glucose causes more insulin to be produced than injecting glucose directly into the bloodstream.
4 Stimulators of insulin secretion
1) Increased plasma glucose
2) Gastrointestinal hormones through feedforward regulation
3) Increased plasma amino acids
4) Parasympathetic nervous system
Inhibitor of insulin secretion
Sympathetic nervous system
Glucagon
Glucagon’s goal is to prevent hypoglycemia
Insulin
(prevents hyperglycemia): Beta cells – secreted in response to glucose, GLP1, PNS, and amino acids – decrease blood glucose, promote anabolic pathways, and are involved with growth
Glucagon
(prevents hypoglycemia): Alpha cells secrete Glucagon in response from low glucose, SNS, amino acids – increases blood glucose, gluconeogenesis, glycogenolysis – catabolic pathways to increase energy.
GLP-1
released from intestine in response to glucose/amino acids – stimulates insulin secretion, increases beta cell mass, anorexigen, decreases glucagon
Diabetes Mellitus
Both types- high blood glucose levels when uncontrolled
3 Stimulators of glucagon secretion
1) Decreased plasma glucose
2) Increased plasma amino acids
3) Sympathetic nervous system
Inhibitor of glucagon secretion
glucagon-like peptide-1 (GLP-1)
Proglucagon
a precursor of glucagon, and several other components. It is generated in the alpha cells of the pancreas and in the intestinal L cells in the distal ileum and colon
3 Active hormones in proglucagon
- Glucagon
- GLP-1
- GLP-2
Type 1 diabetes (Insulin dependent diabetes, juvenile diabetes)
- 10% of all diabetics
- Insulin secretion reduced or absent
- Treated by insulin
Type 2 diabetes (Non–insulin-dependent diabetes, mature onset diabetes)
- 90% of all diabetics
- Defect in insulin secretion and target cell responsiveness to insulin is reduced
Treated by diet, exercise (causes translocation of Glut4 to membrane!!!),
