Back to FlashcardsBiology / OCR Biology A - 5.1.4 - Hormonal Communication Part 2
What does insulin act on
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Key Terms
Term
Definition
What does insulin act on
Hepatocytes; Muscle cells; Adipose tissue; Brain cells
When is insulin secreted
When blood glucose conc is too high
How does insulin work
Binds to receptors which activate a second messenger system
What does insulin do
Increase glucose uptake into cells by facilitated diffusion; Increase respiration rate (glycolysis); Glycogen conversion (glycogenesis) in hepatocytes...
What does glucagon work on
`Hepatocytes and muscle cells | Has spp receptors
When is glucagon secreted
When blood glucose is too low
Related Flashcard Decks
| Term | Definition |
|---|---|
What does insulin act on | Hepatocytes; Muscle cells; Adipose tissue; Brain cells |
When is insulin secreted | When blood glucose conc is too high |
How does insulin work | Binds to receptors which activate a second messenger system |
What does insulin do | Increase glucose uptake into cells by facilitated diffusion; Increase respiration rate (glycolysis); Glycogen conversion (glycogenesis) in hepatocytes and muscle cells; Lipogenesis |
What does glucagon work on | `Hepatocytes and muscle cells | Has spp receptors |
When is glucagon secreted | When blood glucose is too low |
What does glucagon do | Glycogen breakdown (glycogenolysis); Decrease glucose uptake; Converting fatty acids and amino acids to glucose (gluconeogenesis) |
Normal glucose conc | 4-6 mmol dm3 |
When blood glucose conc rises | Detected by beta cells in islets of Langerhans; Secretes more insulin; Hepatocytes and muscle cells remove glucose from blood and convert to glycogen (glycogenesis); Blood glucose falls; -ve feedback |
When blood glucose conc falls | Detected by alpha cells in islets of Langerhans; Pancreas secretes more glucagon; Hepatocytes and muscle cells convert glycogen to glucose and release it in to bloodstream (glycogenolysis); Blood glucose conc rises; -ve feedback |
Describe how insulin secretion is controlled | VG K+ channels in plasma membrane open and K+ diffuses out of beta cell and inside has pd of -70; Blood glucose conc. increases and glucose enters cell; Glucose is phosphorylated then metabolised to form ATP; Presence of extra ATP causes ligand-gated K+ channels to close; K+ cannot diffuse out so membrane potential reduces to only -30; VG Ca2+ open to response in change in membrane potential - Ca move in; Ions cause vesicles to release insulin (exocytosis) into bloodstream |
Processes that lower blood glucose | Glycolysis; Glycogenesis; Lipogenesis |
Processes that increase blood glucose conc | Gluconeogenesis | Glycogenolysis |
Causes of type 2 diabetes | Obesity; Poor diet; Insufficient exercise; Diet high in sugar; Genetics |
Insulin resistance | Symptom of Type 2 diabetes | When the body doesn't respond to insulin |
Hyperglycaemia | High blood glucose |
What can long-term hyperglycaemia lead to | Modification of diff proteins e.g. collagen in blood vessels --> angina and heart failure; Also affects peripheral nerves (poor blood circulation) |
Causes of Type 1 diabetes | Majorly genetically linked but environmental factors such as an infection which causes the immune system to destroy beta cells w/ similar antigens |
Hypoglycaemia | Excessive, abnormal thirst; Frequent urination; Tiredness; Glucose is excreted in urine instead of being used in body |
Why are Type 1 diabetics frequently dehydrated | Glucose increases osmolarity so more water is lost in urine |