Diabetes

Question 1

What is the endocrine gland in the pancreas?

Answer 1

Multiple small clusters of cells thought out the gland called pancreatic islets (islets of langergans) which release secretions into the bloodstream.

Question 2

What do islets do? (A,b,delta)

Answer 2

Islet Alpha cells (a)
-secrete glucagon
-raises blood glucose
-located at periphery of the islet

Islet Beta cells (b)
-secretes insulin
-lowers blood glucose
-mainly found in core of islets

Islet Delta cells
-produce gastrin and somatostatin
-somatostatin inhibits secretion of glucagon and insulin

Question 3

What occurs in the body when there is low blood glucose HYPOglycaemia?

Answer 3

Alpha A cells secrete glucagon
Acts on hepatocytes to
-convert glycogen into glucose (glycogenolyis)
-form glucose from Lactic acid and amino acids (gluconeogenesis)
The release of glucose by hepatocytes increases blood sugar levels to normal
If blood glucose continues to rise, hyperglycaemia inhibits glucagon secretion

Question 4

What occurs in the body when there is high blood glucose HYPERglycaemia?

Answer 4

Beta B cells secrete insulin
-speeds facilitated diffusion of glucose into cells ( increase glucose uptake)
-increases glucose to glycogen (glycogenesis) & uptake of amino acids and protein synthesis & synthesis of fatty acids (lipogenesis)
-decreases glycogenolyis & gluconeogenesis
This decreases blood glucose levels
If blood glucose continue to decrease, hypoglycaemia inhibits the release of insulin.

Question 5

How does the insulin dependant glucose transporter work (GLUT4)?

Answer 5

1.insulin binds to insulin receptor on the surface of cell membrane
2.generation of intracellular signal
3.insertion of GLUT4 receptor from its inactive site into cell membrane
4.transport of glucose across cell membrane

Question 6

What are GLUT4, GLUT2 and GLUT1 responsible for?

Answer 6

GLUT4 - insulin dependant glucose transporter for skeletal muscle & adipose tissue. Inactive inside cell membrane, active when insulin cause it to move from its inactive site to cell membrane

GLUT2 - major transporter of glucose into beta cells and liver cells. Low affinity for glucose and acts when glucose plasma glucose levels are high.

GLUT1- present In all tissue. Does not need actions of insulin. Important for transport of glucose into cells of nervous system.

Question 7

What is the mechanism of islet B cell destruction ?

Answer 7

1. T-cells react agains B cell antigens leading to cell damage
   - T-helpers activate macrophages directed at B -cells
   -Cytotoxic T-cells directly kill B cells
2. Locally produced cytokines (macrophages &cytotoxic Ts) damage B cells

Question 8

What is the insulin action on glucose levels in a normal body?

Answer 8

Pancreas defects glucose in blood through GLUT2 transporters causes a release in insulin
1.insulin binds to insulin receptor
2.receptor is phosphorylated
3.activates cell signaling
4. Releases GLUT4 and GLUT4 imports glucose
5. This lowers blood glucose

Question 9

What are symptoms of type 1 diabetes ?

Answer 9

Hyperglycaemia (random plasma glucose less than 48 mol/L) & characteristic features

Children
- polyuria ( increased urination)
-polydipsia (increased thirst)
-weight loss
-excessive tiredness

Adults
-ketosis
-rapid weight loss
-under 50 yrs old
-BMI under 25kg/m2
-personal/family history of autoimmune disease

Question 10

What is the difference between type 1 and type 2

Answer 10

Type 1 - absolute insulin deficiency
Type 2 - insulin resistance with relative deficiency of insulin

Question 11

Signs and symptoms of type 2 diabetes

Answer 11

Polydipsia (increased thirst)
Polyuria (increased urination)
Blurred vision
Unexplained weight loss
Recurrent infections (UTI)
Tiredness
Skin condition dark colouration in folds

Question 12

Diagnosis of type 2

Answer 12

HbA1c of 48mmol/mol PLUS
Fasting plasma glucose 7 mmol/mol PLUS
Random plasma glucose 11.1 mmol PLUS & in present of symptoms
No additional features of type 1 diabetes (rapid onset, childhood, insulin dependence, ketoacidosis)