Jones- Pancreas

based on pp and easygen

What cells of the pancreas secrete insulin?

b-cells

What cells of the pancreas secrete glucagon?

a-cells

What cells of the pancreas secrete somatostatin?

d-cells

Blood flow in the cells of the pancreas flow from…

the center to the periphery

Insulin is what kind of hormone?

a. steroid

b. peptide

c. fatty acid

d. thyroid

b

Does insulin have a short or long half-life?

short

Measuring C-peptide tells us what?

how much insulin was made in the pancreas

What is the major stimulus for insulin release?

glucose

Besides glucose, what are some other stimuli that can cause the release of insulin from beta cells?

• parasympathetic stimulation

• Ach (Acetyl Choline)

• Incretins

What GLUT transporter is located on b-cells of the pancreas?

a. GLUT1

b. GLUT2

c. GLUT3

d. GLUT4

b

The first step of insulin release is that glucose flows down the concentration gradient through __________ transporters in the beta cell.

GLUT2

The second step of insulin release is that glucose undergoes what?

metabolism

When glucose is metabolized it produces what? (step 3)

ATP

The fourth step of insulin release is that an increase of ATP causes what channel to close?

K+ channels

After closing K+ channels, the cell depolarizes and that allows what type of channels to open up?

V-gated Ca++ channels

When the Ca++ levels of the cell start to rise, that causes vesicles full of insulin to undergo __________.

exocytosis

Summary of the steps for insulin release:

1. glucose flows down the concentration gradient through GLUT2 transporter into b-cell

2. glucose undergoes metabolism

3. ATP is produced

4. Increase of ATP causes K+ channels to close (causes b-cell to depolarize)

5. Depolarization allows V-gated Ca++ channels to open

6. rise in intracellular Ca++

7. Increase in Ca++ causes vesicles full of insulin to exocytose

8. Insulin is released into the bloodstream

Sulfonylurea drugs target what step of insulin release? What do these drugs do?

They target the K+ channels. They act like ATP and CLOSE K+ channels.

The insulin receptor is what kind of kinase?

tyrosine

Do tyrosine kinase receptors dimerize?

yes

What are the main physiological actions of insulin? (actions on blood glucose, fatty acids, ketoacids, amino acids, K+ uptake, etc.)

• decrease blood glucose

• decrease fatty acid and ketoacids in the blood

• decrease blood amino acid conc.

• others:

  • increase K+ uptake

  • potentiate the effects of growth hormone

How does insulin decrease blood glucose?

• increase glucose transport into muscle/fat

• increase glucokinase activity (in liver)

• promotes formation of glycogen

• inhibit gluconeogenesis

Upregulating glucose transporters in tissues increases/decreases blood glucose.

decreases

What GLUT transporters are insulin sensitive?

GLUT4

Glucagon is secreted when blood glucose concentration _______.

a. rises

b. falls

b

Like insulin, glucagon is a __________ hormone.

peptide

Besides low blood glucose/ hypoglycemia what are some other things that stimulate the release of glucagon?

• increase AA concentration

• b-adrenergic agonists

• Ach

• exercise

• cortisol

What are some things that inhibit the release of glucagon?

• insulin

• hyperglycemia

• secretin

• somatostatin

• free fatty acids

Glucagon mainly affects which of the following?

a. pancreas

b. muscle

c. adipose tissue

d. liver

d

What are the main actions of glucagon?

• INCREASE GLUCOSE

• stimulate glycogenolysis (liver)

• stimulate gluconeogenesis

• stimulate lipolysis

What type of diabetes is insulin-dependent and is where there is decreased insulin secretion?

type 1 diabetes

What are the causes of type 1 diabetes?

• destruction of b-cells: autoimmune, viral

• inherited diseases

What are the symptoms of type 1 diabetes?

• hyperglycemia (elevated plasma glucose and glucose production)

• glucose in the urine

• dehydration

• vascular changes

• ketoacidosis (bc too much fat—> energy)

Is type 2 diabetes insulin dependent?

no

Type 2 diabetes results from decreases sensitivity of ____________________ to insulin

target tissues

Symptoms of type 2 diabetes:

• elevated insulin levels

• metabolic syndrome: obesity, insulin resistance, hyperglycemia, HTN, atherosclerosis

What is the tx for type 1 diabetes?

insulin injections

What is the treatment for type 2 diabetes?

• diet changes, exercise, weight loss

• insulin injections

• sulfonylurea drugs

• others