Week 14 Diabetes Flashcards Preview

Med 1 UBC Fall 2019 > Week 14 Diabetes > Flashcards

Flashcards in Week 14 Diabetes Deck (123)
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1

Early manifestations of hypoglycemia

- palpitations, tachycardia

- diaphoresis, anxiety

- weakness, hunger, nausea

2

diaphoresis

profuse perspiration

3

Manifestations of prolonged/severe hypoglycemia

- hypothermia

- confusion, hallucinations

- seizure, coma

4

hyperglycemia: early and later manifestations

Early:

- polydipsia, polyuria

- altered vision

- weight loss, mild dehydration

Late:

- cardiac arrhythmias

- coma

5

Location of the pancreas

behind the stomach between the spleen & the duodenum

6

Functions of the pancreas

Mostly exocrine: pancreatic juice contains enzymes for protein digestion 1-3% is islets - endocrine - insulin/glucagon secretion from islets of langerhans scattered throughout exocrine pancreas

7

Beta Cells

Secrete insulin. 65-80% of islet endocrine cells

8

Alpha cells

Secrete glucagon; 15-20% of the total islet;

9

Delta cells

Secrete somatostatin; 3-10% of islet endocrine ;

10

Role of somatostatin

inhibits both insulin & glucagon

11

pancreatic polypeptide cells

PP cells; secrete pancreatic polypeptide 3-5% of islet endocrine cells; Reduces appetite and food intake, thus regulating blood sugar.

12

Parasympathetic innervation of pancreatic islets

Parasympathetic innervation via Vagus nerve; Primary NT is ACh --> stimulates insulin release

13

Sympathetic innervation of pancreatic islets

Postganglionic fibres of the celiac ganglion; Primary NT is NE --> inhibits insulin secretion

14

Insulin synthesis and structure

Insulin is synthesized as proinsulin - mainly in the beta cells, but also in the brain. It is synthesized in RER, processed in golgi and then stored in secretory granules for hours or days before secretion. Proinsulin has A and B chain linked by disulphide bonds with a C peptide.

15

Regulation of insulin secretion

- Glucose is the major stimulator

- there are also neural, hormonal, and nutrient stimulants, but these are also considered glucose-dependent in order to protect agains inappropriate stimulation of insulin and hypoglycemia.

16

Key hormones that stimulate release of insulin

GIP GLP-1 Glucagon (sounds paradoxical, but it does)

17

glucotoxicity & lipotoxicity

prolonged glucose and free fatty acid exposure may cause apoptosis of B cells

18

Mechanism of insulin release from the B cell

1. Glucose enters through a GLUT2 channel

2. Glucokinase cleaves glucose to G6P

3. G6P inhibits an ATP-dependent K+ channel, which stimulates influx of Ca2+ through a voltage-gated Ca2+ channel

4. Influx of Ca2+ stimulates exocytosis of granules containing proinsulin.

19

Biological actions of insulin (conceptually)

- anabolic; promotes energy storage

- Targets muscle, fat, and liver

- critical role in growth and development

20

Action of insulin on muscle and adipocytes

1. Insulin binds receptor on muscle cells and adipocytes

2. Signalling pathway stimulates translocation of vesicles with GLUT 4 transporters to cell surface

3. Glucose enters cells

21

Outcomes of insulin in adipose tissue

Lipogenesis (decreased lipolysis)

22

Outcomes of insulin in striated muscle

Glycogen and protein synthesis

23

Outcomes of insulin in the liver

Glycogen synthesis;

Lipogenesis (decreased gluconeogenesis)

24

The insulin receptor

A tyrosin kinase; 2 alpha subunits and 2 beta subunits.

25

Glucagon synthesis

- Synthesized as proglucagon in intestinal L cells and in pancreatic cells

- Proglucagon contains other glucagon-related peptides (GLPs)

26

Action of glucagon

- major site of action is in the liver (in contrast to insulin, which works on many tissues)

- Stimulates glycogenolysis and gluconeogenesis

- Aims to maintain blood glucose during fasting and exercise

27

where is glucagon cleared?

in the renal capillary bed

28

Stimulants of glucagon (hormonal, neural, nutrients)

- Hormonal: GIP and CCK

- Neural: ACh and NE

- Nutrients: low glucose and Ala or Arg

29

Action of cortisol in carbohydrate metabolism

- counterregulatory to insulin action (works like glucagon)

- Increases hepatic gluconeogenesis to maintain plasma glucose during fasting

30

Action of growth hormone in carbohydrate metabolism

Counterregulatory to insulin action and inhibits insulin.