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PancreasTwo cell types to produce:

1. digestive enzymes – exocrine glands (acini)

2. hormones – islets of Langerhans

1 – 2% of pancreas are the islets of Langerhans

Islets of LangerhansTwo hormones are produced:

1. insulin – beta (β) cells

2. glucagon – alpha (α) cells

blue = cell nucleigreen = insulinred = glucagon

Hormone Structureinsulin

peptide hormone

glucagonpeptide hormone

Insulin and glucagon are referred to as antagonistic hormones.

GlycogenA glucose polymer

made up of many glucose subunits

“Storage form of glucose”

Stored within liver and muscle

Action of Insulin

Beta cells ofpancreas are stimulatedto release insulininto the blood.

Insulin

Liver takesup glucoseand stores itas glycogen.

Body cellstake up moreglucose.

Blood glucose leveldeclines to set point;stimulus for insulinrelease diminishes.

STIMULUS:Rising blood glucose

level (for instance, aftereating a carbohydrate-

rich meal)

Homeostasis:Blood glucose level

(about 90 mg/100 mL)

Blood glucose levelrises to set point;

stimulus for glucagonrelease diminishes.

STIMULUS:Dropping blood glucoselevel (for instance, after

skipping a meal)

Example of Insulin’s Effect on Body Cells - Muscle Cell

Insulin Receptors

Insulin

GLUT 4 Protein Vesicles

GLUT 4 Transporters (proteins that transport glucose across plasma membrane)

Signal Transduction Pathway

Exocytosis

Glucose

OUTSIDE CELL

INSIDE CELL

When is insulin released? after eating

hyperglycemia

beta cellscellular signals for

insulin releasedecreased blood

sugar

increased glucose uptake

glycogen production in liver

Liver takesup glucoseand stores itas glycogen.

Blood glucose leveldeclines to set point;stimulus for insulinrelease diminishes.

STIMULUS:Rising blood glucose

level (for instance, aftereating a carbohydrate-

rich meal)

Homeostasis:Blood glucose level

(about 90 mg/100 mL)

Blood glucose levelrises to set point;

stimulus for glucagonrelease diminishes.

STIMULUS:Dropping blood glucoselevel (for instance, after

skipping a meal)

Alpha cells of pancreasare stimulated to releaseglucagon into the blood.

Liver breaksdown glycogenand releasesglucose intoblood.

Glucagon

Action of Glucagon

What does glucagon do? breaks down glycogen

hypoglycemia

alpha cellscellular signals for glucagon release

increased blood sugar

glucose release from liver

glucose production in liver

Diabetes Mellitus – Type Ialso known as juvenile diabetes or

insulin-dependent diabetes

Causeimmune system attacking insulin-

producing beta cellsno insulin production

Symptomsincreased thirst, hunger and urination

Treatmentdaily dosage of insulin

Diabetes Mellitus – Type IIalso known as adult-onset diabetes or

non-insulin-dependent diabetes

CausePoor diet, lack of exercise

Excess glucose in the blood for a long period of time causes the pancreas to become overworked and tired

Beta cells produce some, but not enough insulin (deficiency)

A reduction in the number of functional insulin receptors

reduced responsiveness of cells to insulin = insulin resistant

Symptomsincreased thirst, hunger and urinationfatigue / lethargy

Type II DiabetesTreatment

maintain healthy diet and frequent exercise

medication only upon progression of disease state

Regular exercise can reduce and stop symptoms

Insulin GLUT 4 Protein Vesicles

Exocytosis

Exercise GLUT 4 Protein Vesicles

Insulin GlucoseGlucose

Canadian ConnectionFrederick Banting & Charles

BestNobel Prize – 1923Insulin isolation

tied off ducts to digestive tract

cell producing digestive enzymes shrivelled

only islets of Langerhans remained

Video TestimoniesUniversity of Alberta

developed islet cell transplant method

Islet Transplant Animation

Photo Journal

News Feature

Spinal cord(cross section)

Nervesignals

Nervecell

Releasinghormone

Stress

Hypothalamus

Anterior pituitary

Blood vessel

ACTH

Adrenalgland

Kidney

Adrenal medullasecretes epinephrineand norepinephrine.

Adrenal cortexsecretesmineralocorticoidsand glucocorticoids.

Effects of epinephrine and norepinephrine:

1. Glycogen broken down to glucose; increasedblood glucose

2. Increased blood pressure

3. Increased breathing rate

4. Increased metabolic rate

5. Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity

Effects ofmineralocorticoids:

1. Retention of sodiumions and water bykidneys

2. Increased bloodvolume and bloodpressure

Effects ofglucocorticoids:

1. Proteins and fatsbroken down andconverted to glucose,leading to increasedblood glucose

2. Immune system maybe suppressed

(b) Long-term stress response(a) Short-term stress response

Nerve cell

Stress Regulation

Classwork/HomeworkSection 8.2 – Pg. 383 #1-8,9