Pancreas Flashcards
Describe role of pancreas:
Release digestive enzymes
~~>amylase, protease, lipase
Control blood glucose levels
State the difference between exocrine glands and endocrine glands?
Exo –> release chemicals into a duct
Endo –> releases hormones into blood stream
What is the pancreatic acini?
Exocrine tissue
Darker stain
Small berry-like clusters
Produce = secrete digestive enzymes
Goes to pancreatic duct —> duodenum
What are the Islets of Langerhans
Endocrine tissue
Lightly stained
Large spherical clusters
Produce + secrete hormones
Capillaries –> transport hormones in blood stream
What are the two types of cells in the Islets of Langerhans?
Alpha cells –> produce glucagon
~~>increase blood glucose level
(larger)
Beta cells –> produce insulin
~~> decrease blood glucose levels
Regulated by negative feedback
Describe glycogenesis?
Converting glucose to glycogen
Describe gluconeogenesis?
Converting amino acids + glycerol to glucose
Describe glycogenolysis?
Converting glycogen to glucose
What is the value for normal blood glucose levels?
90mgcm-3 of blood
What causes blood glucose levels to rise?
Intake of food
~~> carbs broken down = glucose released
Gluconeogenesis
Glycogenolysis
What causes for blood glucose levels to decrease?
Exercise
~~> glucose used in respiration
Fasting
Glycogenesis
What happens when blood glucose levels rise?
Beta cells –> release insulin
Target liver + most body cells
Decrease levels of glucagon released by alpha cells
Increase of glucose uptake into cells (skeletal muscle cells=)
Increased respiration rate
Increase conversion of glucose to fat
Increases glycogenesis
What happens when blood glucose concentrations decreases?
Alpha cells release glucagon
Target liver + fat cells
Increases glycogenolysis
Decrease glucose intake into cells
Increase rate of gluconeogenesis
Why is it important we maintain our BGL at normal levels?
BGL –> affect WP gradient of cells
Too high = more water leaves via osmosis –> dehydrated
Too low -= more water enters via osmosis –> cell lysis
Both cases = disrupt concentrations of other chemicals in cell
Inability to do this = diabetes
What happens to a beta cell when there are normal levels of glucose?
Resting potential = -70mV
Potassium channels =open
~~> K+ diffuse out of cell
V-gated Ca 2+ channels = closed
What happens to a beta cell when there are high levels of glucose?
(6 marks)
Glucose transporters move glucose into B cells.
Mitochondria metabolises glucose (aerobic respiration) –> release ATP.
High ATP level within beta cell cause K+ channels to close
~~> stops K+ moving out of the cell
Leads to build up of K+ inside beta cell
—-> depolarisation of cell membrane (-30mV)
Causes V-gated Ca2+ channels to open –> influx of Ca2+
Secretory vesicles within insulin move + fuse with plasma membrane —> exocytosis
What is diabetes?
Inability to metabolise glucose properly
hyper/hypoglycaemia
What is Type 1?
B cells cannot make insulin
Cause = unknown
Autoimmune response to B cells
What is Type 2?
B cells = not enough insulin
Cells not sensitive to insulin
Causes:
*Obesity
*Bad diet
Glycoprotein insulin receptor = malfunctioning
What are the treatments for Type 1 diabetes?
Insulin injection
Pancreas transplant
Stem cell therapy
What are the treatments for Type 2 diabetes?
Regulate carb intake
Regular exercise
Drugs
Insulin injection
Why is bacteria GM to make human insulin?
Higher yield –> easy to grow bacteria
Purer insulin –> lower risk of allergy
Cheaper
No religious/ethical concerns
Why was GM of bacteria used?
Problems with pig insulin:
–> Allergy
–> Religious
–> Problems with purification.
What issues arise from Type 1 diabetes treatment?
Transplant:
–> Rejection
–> Low organ availability
Hard to inject B cells
What are the advantages for stem cell treatment?
No donors
No rejection
Cure/permanent
What are the disadvantages of stem cells as treatment?
Difficult to control differentiation
~~>risk of tumour
Ethical concerns over using embryos
How to overcome disadvantages of using stem cells?
Use ‘spare’ embryos from IVF
Make more SCs from initial embryos
Create embryonic SCs from somatic cell nuclear transfer
