Pancreas & Fuel Metabolism Flashcards
What is anabolism?
[ARNIE]
SYNTHESIS of larger molecules from smaller
What is catabolism
DEGREDATION of large molecule into smaller molecules
(through hydrolysis, oxidation)
What is glycogenesis?
Glucose → glycogen
CONSEQUENCE = Decrease blood glucose
What is glycogenolysis?
Glycogen → glucose
CONSEQUENCE = Increase blood glucose
What is gluconeogenesis?
A.a’s → glucose
CONSEQUENCE = Increase blood glucose
What is protein synthesis?
A.a’s → protein
CONSEQUENCE = Decrease blood a.a’s
What is proteolysis? (protein degradation)
Protein → a.a’s
CONSEQUENCE = Increase blood a.a’s
What is lipogenesis? (fat synth.)
Fatty acids & glycerol → triglycerides (fat/lipids)
CONSEQUENCE = Decrease blood fatty acids
What is lipolysis? (fat degradation)
Triglycerides (fat/lipids) → fatty acids & glycerol
CONSEQUENCE = Increase blood fatty acids
What is the absorptive (FED) state?
UNDER THE INFLUENCE OF INSULIN
Glucose major source of energy.
–excess glucose stored in liver & muscle as glycogen
→HOWEVER, this gets ‘filled up’, THUS rest is converted into fatty acids & glycerol
–excess circulating fatty acids must be incorporated into triglycerides
–proteins are synthesised.
–excess circulating _a.a’_s converted to glucose & fatty acids (ultimately stored as triglycerides)
What is the postabsorptive (FASTED) state?
UNDER THE INFLUENCE OF GLUCAGON
Energy stores mobilised to provide energy.
(stops net synth. of glycogen, fat & protein)
–Glycogen degraded to glucose in liver & musle
–Catabolism of triglycerides into fatty acids & glycerol in adipose tissue is increased
–Glycerol reaching liver converted to glucose
–Many cells (e.g. aerobic muscle fibres) catabolise fatty acids (glucose sparing)
–Increased uptake a.a’s into liver, and gluconeogenesis maintains hepatic output of glucose.
What are the 2 (main) types of pancreatic endocrine cells?
Beta cells secrete insulin
→ DECREASE blood GLUCOSE
Alpha cells secrete glucagon
→ INCREASE blood GLUCOSE
[Delta (D) cells secrete somatostatin]
→ decrease gastric secretion, inhibit digestion of nutrients
[PP cells secrete pancreatic polypeptide]
→ an effect on appetite, & alterations to GI motility
How does glucose stim. insulin secretion?
Glucose entry →
Oxidative metabolism →
↑ATP →
Inhibition of KATP channels →
depolarisation →
opening of voltage-‐sensitive Ca2+ channels →
↑[Ca2+]i →
insulin secretion
How does the endocrine system regulate blood glucose?
When blood glucose lvls decrease, endocrine cells in pancreas SECRETE glucagon to stim. glucose release from liver & decrease secretion of insulin
How does the nervous system regulate blood glucose?
Neurons in hypothalamus sense glucose lvls, & through nerve connections stim. release of adrenaline
How many types of glucose transporters are there (the main types)?
Which are regulated by insulin?
GLUT 1-4
–GLUT 1, 2 & 3 are NOT regulated by insulin
–GLUT 4 regulated by insulin
What is the function of GLUT 1?
Facilitates transport glucose across cell mem. of cells
(e.g. acrodd BBB)
What is the function of GLUT 2?
Principal transporter for transfer glucose betw. liver & blood, and for renal glucose reabsorption
What is the function of GLUT 3?
Main transporter of glucose into neurons
What is the function of GLUT 4?
SKELETAL MUSCLE AND ADIPOSE CELLS
What are the 3 main functions of insulin?
–Promotes glucose entry into skeletal muscle & adipose cells
–Promotes glucose utilisation
–Liver cells can store excess glucose as glycogen
