WEEKS 5 & 6: Pancreas and Diabetes Flashcards
The average adult human has about … litres of blood
5
Humans derive energy from food in what 3 main forms?
Carbohydrates, proteins
and lipids.
During digestion we absorb … from carbohydrates, … from proteins and … from lipids.
glucose
amino acids
fatty acids
If we do not utilise consumed nutrients immediately for energy we store them as larger macromolecules via … reactions.
anabolic
T or F
Glycogen has a similar structure to starch?
T
T or F
Glucose molecules can be easily joined together to form the storage molecule glycogen
T
Glycogen is mainly stored in the … and …
liver and muscles
When you exercise muscle glycogen can be catabolised to provide energy for …
contraction
(But glucose is also taken up from the blood to ensure muscles have sufficient energy to
keep contracting.)
T or F
Neurons in the central nervous system can store glycogen.
F
It is estimated that the brain requires up to …% of your body’s glucose.
50%
T or F
A constant supply of glucose must be provided for normal brain function.
T
Ketone bodies, are by-products of ……
fat-metabolism
When glucose is limited, the brain is capable of switching to an alternative energy source to maintain normal function. This “back-up” energy source is called …
ketone bodies
T or F
Glucose is usually present in the urine.
F
When glucose is present in the urine this is an indicator of?
The glucose load in the kidney tubules exceeds the reabsorption capacity, aka hyperglycemia.
T or F
Plasma glucose concentrations do not fluctuate that much across the day, despite consuming meals.
T
What two metabolic hormones control glucose homeostasis?
Insulin and glucagon
Why is glucagon a difficult hormone to measure in blood?
It is rapidly degraded and thus has a very short half-life, of less than 6 minutes.
Glucagon is important between meals in the ….. state where it increases blood glucose.
post-absorptive
…. is important in preventing any decline in blood glucose
between meals.
glucagon
When are hormones aside from glucagon and insulin required for glucose homeostasis?
During starvation
Insulin prevents …
a) excess blood glucose “hyperglycaemia”
b) low blood glucose “hypoglycaemia”.
a
Glucagon prevents …
a) excess blood glucose “hyperglycaemia”
b) low blood glucose “hypoglycaemia”.
b)
What are the consequences of chronic hyperglycemia?
Osmotic diuresis, frequent urination, increased thirst and damage to blood vessels.
T or F
The pancreas has both exocrine and endocrine functions.
T
The pancreas is a small, leaf-like gland located in the …, posterior to the stomach.
retroperitoneum
The retroperitoneum is posterior to the …
stomach
T or F
Acinar cells are endocrine cells
F
They are exocrine
T or F
acinar cells arranged in lobules
T
What do acinar cells secrete?
a range of digestive enzymes, sodium bicarbonate and other electrolytes
Where do acinar cells secrete digestive enzymes into?
The duodenum (part of the small intestines)
T or F
The Islets of Langerhans are 98%-99% of pancrease mass
F
(only 1-2% of pancreatic mass)
The islets of Langerhans secrete what into where?
hormones into systemic blood.
Are islets of langerhans cells part of the endocrine or exocrine systems?
Endocrine
Do beta cells in the islet of Langerhans produce insulin or glucagon?
Insulin
Do alpha cells in the islet of Langerhans produce insulin or glucagon?
Glucagon
T or F
Beta cells circle the edge of the islet of Langerhans whilst alpha cells are in the center.
F
Vice versa
What triggers glucagon release from alpha cells in the islet of Langerhans?
Amino acids
The pancreas receives oxygen-rich blood through the … system and gives off oxygen-poor blood flow through the … system
arterial
venous
T or F
The small intestine will deliver nutrient poor blood to the pancrese via the portal vein.
F
nutrient rich
The small intestine will deliver nutrient-rich blood to the pancreas via the …
portal vein
When nutrient-rich blood is delivered to the pancreas from the small intestine it triggers a release of what?
Hormones such as insulin and glucagon
Hormones secreted from the pancreas through the portal vein travel straight to which organ?
The liver
Insulin and glucagon from the pancreas will have how many times greater effect in the liver than the rest of the body?
4x
What are the three major types of endocrine cells within the Islet of Langerhans in the pancreas?
Beta, alpha and delta cells
Delta cells in the islet of Langerhans in the pancreas secrete what?
somatostatin
What affect does somatostatin have when secreted by delta cells in the pancreas?
act locally within pancreas to inhibit both insulin and glucagon secretion
Impaired insulin secretion or insulin action results in the metabolic disease called
diabetes mellitus
What affect does insulin have when secreted by beta cells in the pancreas?
anabolic, promotes storage of glucose, fatty acids and amino acids in cells
What affect does glucagon have when secreted by alpha cells in the pancreas?
catabolic, mobilises glucose, fatty acids and amino acids for energy production
T or F
Insulin is the only blood glucose lowering hormone in the body
T
T or F
Diabetes mellitus and diabetes insipidus are roughly equally common
F
diabetes insipidus is less common
Diabetes insipidus, is related to endocrine dysfunction associated with what hormone?
anti-diuretic
Why is there no disease state that exists for glucagon insufficiency?
A lack of glucagon secretion and/or action can be compensated for by other hormones
The only time excess glucagon production occurs is in …
glucagonoma
What is a glucagonoma?
a tumour of the pancreatic alpha cells that hyper-secretes glucagon.
T or F
Glucagonoma is a common condition
F
Rare
Who are most at risk of developing a glucagonoma?
typically occurs in elderly men who suddenly develop symptoms of type 2 diabetes mellitus but with weight loss (not gain).
A person with elevated blood glucose levels will likely exhibit increased secretion of … from their pancreatic … cells
insulin
beta
T or F
insulin promotes glucose uptake by all cells in the body.
F
The three key target tissues of insulin are …
the liver (hepatocytes), muscle (both skeletal and cardiac muscle), and fat (adipose cells).
T or F
Insulin promotes glucose uptake into neurons in the central nervous system
F
insulin does not promote glucose uptake into neurons in the central nervous system, something which is critical to normal function!
Carrier-mediated transport exhibits the properties of …
specificity, competition, and saturation.
What is the most important sugar in the body?
Glucose
Glucose transporter GLUT 1 mediates …
basal glucose uptake (insulin-independent)
Which is the only glucose transporter (between Glut 1 - Glut 5) that is insulin-dependent?
GLUT 4
Which two glucose transporters (between Glut 1 and Glut 5) mediate glucose uptake
Glut 2 and Glut 4
Which glucose transporter (between Glut 1 and Glut 5) is important for the blood-brain barrier and erythrocytes?
Glut 1
Which two glucose transporters (between Glut 1 and Glut 5) mediate basal glucose uptake?
Glut 1 and Glut 3
Which glucose transporter is found in muscle myocytes and fat adipocytes?
GLUT 4
Which glucose transporter is expressed on intestinal epithelial cells?
GLUT 5
Which glucose transporter is involved in fructose transport?
GLUT 5
Insulin promotes … uptake into cells.
glucose
In muscle and adipose tissue in an unstimulated state, dormant GLUT 4 is stored in …
cytoplasmic vesicles
Activation of cells by insulin initiates … which activates … which then promotes the translocation of glucose transporters to the cells surface.
IRS
PI3K/PKB
The physiological homeostatic control system that senses glucose and produces an appropriate secretion of insulin resides solely within the ….. cells.
pancreatic beta
Glucose enters beta cells via …., down the glucose concentration gradient.
GLUT2 transporters
Why is GLUT 2 regularly expressed on the beta cell membrane?
because GLUT2 is not insulin dependent
T or F
The amount of ATP produced in beta cells is proportion to the glucose entry.
T
T or F
Blood glucose is the only regulator of insulin secretion
F
During digestion, signals from the parasympathetic nervous system, together with hormones from
the gastrointestinal tract, glucose and other nutrients, produce an appropriate insulin response.
The parasympathetic nervous system releases … that … insulin secretion
acetylcholine
stimulates
The sympathetic nervous system releases … that … insulin secretion
noradrenaline
inhibits
T or F
The liver is a key metabolic organ.
T
T or F
GLUT4 has very minor expression in hepatocytes.
T
In hepatocytes the main glucose transporter is GLUT…
2
How does insulin promote glucose uptake in the liver after a meal?
via expression and activation of enzymes that either promote glucose storage or utilisation of glucose.
T or F
Hepatocytes promote fat synthesis
T
Carbohydrates decreases blood glucose by…
promoting uptake by cells (utilization & storage as glycogen), whilst blocking two mechanisms by which liver increases glucose output into blood (gluconeogensis and glycogenolysis).
Glucagon is synthesised by the …… cells
pancreatic alpha
T or F
Glucagon acts as a functional antagonist to insulin in most circumstances.
T
T or F
Insulin is catabolic, whilst glucagon is anabolic.
F
Insulin is anabolic, whilst glucagon is catabolic.
T or F
Hypoglycaemia stimulates glucagon secretion, whereas hyperglycaemia inhibits glucagon release.
T
Increased …… concentrations in the blood stimulate both insulin and glucagon.
amino acid
T or F
Low blood fatty acid concentrations in the blood will stimulate insulin release.
F
Low blood fatty acid concentrations in the blood will stimulate GLUCAGON release. This is opposite to insulin
How can the sympathetic nervous system increase glucagon secretion?
via secretion of noradrenaline and adrenaline and the stress hormone cortisol.
T or F
Glucagon does not influence blood amino acid levels, and has a limited protein metabolic effect.
T
Which of the following is consistent with the function of glucagon?
a) Promotion of glycogen synthesis in hepatocytes
b) Stimulating glycogen breakdown in the liver and release of glucose into the blood
c) Inhibition of gluconeogenesis in the liver
d) Activation of protein catabolism in the skeletal muscle and formation of substrates for gluconeogenesis
b)
T or F
Diabetes insipidus is closely related to diabetes mellitus
F
Not related at all
What kind of person can develop gestational diabetes?
A pregnant person
