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Pancreas + diabetes (Transporters (GLUT (GLUT 3 (Brain (Higher affinity…
Pancreas + diabetes
Transporters
Facilitated glucose transporters (GLUT)
- Glucose transported into cells via facilitated diffusion
Sodium dependent glucose transporters
- Glucose uptake from intestinal lumen into villi of lining
GLUT
-
GLUT 4
Muscle + adipose tissue
: Signalling cascade culminate movement cytoplasmic vesicles towards cell surface membrane
INSULIN SENSITIVE uptake glucose after food intake
Medium affinity.
Recruits transporters from intracellular stores, increasing glucose uptake
GLUT 2
Liver , kidney, intestine, pancreatic beta cell
Lower but high. Intracellular + extracellular equillibrate across membrane
Glucose entry proportional to blood glucose levels
-
GLUT 1
Brain, erythrocytes, placenta and fetal tissue
-
- Higher affinity transporters: brain
- Liver not insulin dependent glucose uptake . Insulin accelerates uptake via GLUT 2 in liver
Function
-
Exocrine
- GI tract: secreting digestive enzymes
-
Diabetes
Type 2
- Peripheral tissues not as responsive to insulin, more insulin produced beta cells compensate (hyperinsulinaemia)
- Function of beta cells decline, cannot compensate for insulin resistance hyperglycaemia - diabetes
- Usually over 40
- Obesity major risk factor
Type 1
- Autoimmune destruction beta cells
- Little/no insulin produced
- In childhood/before 40
- Insulin treatment
- Thirst, polyuria and weight loss
- Body uses lipids and proteins to make glucose
- Uncontrolled catabolism: Ketoacidosis
- Peripheral lipolysis: circulating free fatty acicds
- Converted into acidic ketones in liver: metabolic acidosis
Pancreas
- Retroperitoneal (apart from tail)
- 12-15cm long
- Lateral to medial: tail - body- neck- head - unicinate process
- Head and uncinate process enclosed in 3/4 duodenum
Insulin
- Beta cells
- 2mg secreted per day
- 6-10 mg in pancreas
- High blood glucose:
- Stimulated PSNS
- Intestine secretes incretins (gastric inhibitory polypeptide (GIP) and glucagon like polypeptide -1 (GLP-1) when glucose ingested - stimulates release of insulin
- Increase uptake + storage of glucose (lowers blood glucose levels)
- Glucose stored as glycogen
- Insulin targets glucose uptake in liver, muscle and adipose tissue
Glucagon
- Alpha cells
- Secreted response low blood glucose level (fasting)
- Targets mainly liver, stimulate breakdown glycogen to glucose
- Inhibits glycogen/fatty acid synthesis (diminishing production of pyruvate)
- Gluconeogenesis in liver
- Inhibits glycolysis
- Glucagon release glucose from liver cells, increase blood glucose levels
-
Insulin in liver
- GLUT 2 not dependent insulin, accelerates glucose uptake liver
- Glucokinase sites occupied by glucsoe, phosphorylated into G6P
- Increase in G6P build up glycogen stores
- glycogen released as glucose