The pancreas (Week 7) Flashcards
what is the pancreas
an accessory organ of digestion with both endocrine and exocrine functions
what does the exocrine release
bicarbonate and pancreatic lipases and proteases
what does the endocrine release
glucagon and insulin
where is the pancreas found
found retroperitoneally at about level L1/L2
acinar cells function
synthesize and secrete digestive enzymes
islet of langerhans function
regulation of blood glucose levels
alpha cells produce what
glucagon
beta cells produce what
insulin
delta cells produce what
somatostain
f cells produce what
pancreatic polypeptide
in the synthesis of insulin what is the first stage
transcription. Insulin gene found in DNA of beta cell. mRNA forms
in the synthesis of insulin what is the second stage
translation. mRNA enters cytoplasm, ribosomes read mRNA and preproinsulin is formed.
in the synthesis of insulin what is the third stage
preproinsulin. 3 parts. signal sequence, insulin chain, connecting pepetide (C peptide) signal leads preproinsulin to ER
in the synthesis of insulin what is the fourth stage
processing of ER. Signal sequence removed. Proinsulin formed
in the synthesis of insulin what is the fifth stage
formation of insulin and C peptide. proinsulin now in golgi. proinsulin cleaved to mature insulin and C-peptide
insulin release
fasting blood glucose = 4-5 mmol l-1
post prandial blood glucose = up to 10 mmol l-1
what stimulates the release of insulin
blood glucose concentration
amino acids
- leucine, isoleucine, alanine and arginine
incretins
- GIP and GLP-1
Glucagon
hyperkalaemia
Vagal nerve stimulation
what inhibits the release of insulin
Norepinephrine and epinephrine
somatostatin
stimulation of alpha cells in release of glucagon
rising concentrations of amino acids
- arginine and alanine
GIP
Hypoglycemia
epinephrine
inhibition of alpha cells in the release of glucagon
amylin, insulin and somatostatin
insulin
GLP-1
Hyperglycaemia
what is glycogenolysis
Glycogenolysis is the biochemical process by which glycogen, a polysaccharide (complex sugar) that serves as a storage form of glucose, is broken down into individual glucose molecules.
what is the effect of hypoglycaemia
blood glucose levels <4 mmol l-1
low blood glucose deprives neurones of source of fuel
- neuroglycopenia
- counter-regulatory responses
can be side effect of management of Diabetes Mellitus
-whipple triad
what is the effect of hyperglycemia
blood glucose level > mmol l-1 before eating
chronic state can lead to altered nutrient metabolism
- glycated proteins
- osmotic diuresis
what is type 1 diabetes
autoimmune disease b cell destruction
absolute insulin deficiency
what is type 2 diabetes
progressive loss of b cells insulin secretion
insulin resistance
what is gestational diabetes mellitus
diabetes diagnosed in 2nd and 3rd trimester of pregnancy
no clear over diabetes prior to gestation
T1DM- aetiology and common features
Genetic predisposition (polygenic)
Environmental tigger (viral infection)
autoimmune response - destruction of pancreatic B cell
most common in childhood and adolescence
T2DM - aetiology and common features
genetic and epigentic factors
environmental factors (sedentary lifestyle, obesity)
inulin resistance and dysfunction of pancreatic B cells
