PHYS Overview of Diabetes & Complications - Week 12

Question 1

Compare and contrast high and low affinity GLUTs.

Answer 1

High affinity GLUTs transport glucose even at low concentrations. Low affinity transports don’t.

Question 2

Constant vs inducible expression GLUTs?

Answer 2

Constant - always present on plasma membrane.
Inducible - stored within intracellular vesicles & must be stimulated to migrate to the plasma membrane & enable uptake.

Question 3

What is the affinity & expression of GLUTs in adipose tissue?

Answer 3

High affinity, inducible expression.

Question 4

Describe what part of the pancreas (endo/exo), what cells and mechanism of insulin secretion?

Answer 4

Islets of Langerhans @ endocrine pancreas – secrete regulatory hormones (e.g., insulin & glucagon) directly into the bloodstream.
B-cells: high glucose levels in bloodstream -> glucose enters B-cells via GLUT1/2 -> ATP production -> closure of K+ channel -> build up of intracellular K+ -> increasing positive charge of intracellular environment -> threshold reached -> Ca2+ enters -> exocytosis of insulin vesicles (70% endocrine pancreas secretions).

Question 5

What 4 x factors trigger insulin secretion?

Answer 5

• Increasing glucose levels
• Increasing amino acid levels
• Secretion of incretins @ digestive tract cells
• PARASYMP activation.

Question 6

What do a-cells secrete?

Answer 6

Glucagon.

Question 7

What is the function of glucagon? What processes does it trigger @ liver, muscles, adipose tissue?

Answer 7

Raise BGL.
Gluconeogenesis, glycogen breakdown, lipolysis.

Question 8

What is the function of insulin? What processes does it trigger @ liver, muscles, adipose tissue?

Answer 8

Lowers BGL.
Glycogen production. Glycogen production & protein synthesis. Lipogenesis.

Question 9

Type I vs Type II diabetes patho.

Answer 9

I - loss of insulin function. II - dysfunctional signalling.

Question 10

Risk factors of Type I diabetes.

Answer 10

• Changes in intestinal microbiota
• Respiratory infections
• Cow’s milk
• Weight gain
• Toxins
• B-cell stress (via low physical activity, psychological stress, trauma, glucose overload, infection, puberty, rapid growth).

Question 11

Risk factors of Type II diabetes.

Answer 11

• Obesity
• FHx
• Lack of exercise
• Unhealthy eating.

Question 12

Effects of T1 diabetes.

Answer 12

• Reduced protein synthesis -> lean body mass -> reduced muscle performance -> fatigue.
• As cells can’t rely on glucose, cells rely on other sources = ketones -> increased plasma H+ -> ketoacidosis/DKA.

Question 13

Effects of T2 diabetes.

Answer 13

• Hyperglycaemia.

Question 14

Describe the effects of chronic hyperglycaemia in terms of both macro- & micro- vascular damage.

Answer 14

• Macrovascular:
• Ischaemic heart disease
• Stroke
• Peripheral vascular disease
• Microvascular:
• Retinopathy
• Gangrene – due to loss of blood flow & nerve function in extremities -> lack of awareness re damage to skin
• Nephropathy – leakage of glucose & other products into the filtrate.

Question 15

Normal BGL. Healthy BMI range. Target HbA1c range.

Answer 15

Normal BGL <5.5mmol/L.
Healthy BMI Range 20-25.
Target HbA1c range <7%.

Question 16

Function of GLUT4. Function of GLUT2.

Answer 16

GLUT4 is responsible for glucose uptake in response to insulin.
GLUT2 is involved in helping to release insulin the B cells.