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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
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