Pancrease and Glucose RegulationDiabetes frames the debate?Cells need sugar—ATP and the Krebs CycleOther nutrientsRole of liver in processing nutrients, storing glucoseRole of pancreas (as endocrine organ) in controlling sugar levels in the blood via insulin and glucagon secretionMetabolic pathways after meal (absorptive) and between meals (post-absorptive) Type I DiabetesType II Diabetes and Pima IndiansThe case for Food

Diabetes mellitus—”starvation amidst plenty”

Type IJuvenile onset

Pancreas beta cells destroyed, no insulin produced

Type II“Adult onset” (seen more frequently in children recently)

Complicated set of factors, some insulin production

Goal—understand role of insulin

Cells and GlucoseAll cells of body need constant glucose supply, especially nervous tissueMost other nutrients can be converted into glucose or derivatives for making ATPATP is celluar “gasoline”

Glycolysis, Kreb’s Cycle, Electron Transport Chain

Main way that cells make ATP

Glucose is principle reactant

Why not eat just sugar?

Essential Amino AcidsOnly additional nutrients that body can’t produce

Needed for making proteins

Also some vitamins and minerals must come from diet

What happens to the rest of what we eat?

Interconversion of NutrientsAlmost everything we eat can be converted and used by Kreb’s cycle

We need some other nutrients—essential amino acids, vitamins, minerals

Our body also uses fats and proteins directly from diet

Roughage or fiber also important for digestive tract function and long-term health

Why not eat just sugar?

What keeps sugar constantly available in blood?

Immediately after a meal, nutrients are flowing into blood across wall of stomach, small intestinesBetween meals, when food has mostly been digested, nutrients are not availableNonetheless, blood sugar levels are kept virtually constantHow is this possible?

Role of liver in temporary storage of glucose as glycogenDifferences in “absorptive” and “post-absorptive” metabolic pathwaysRole of pancreas as enodcrine organ to release insulin (B-cells of islets) and glucon (A-cells of islets) to regulate process

Liver and Pancreas

REVIEW:Liver

STRUCTURELarge ventral organ of abdominal cavity with multiple lobes (learn them!!)Sets against inferior surface of diaphragm on left sideForms as outpocketing of gut--common bile duct is left as connectionBile duct is two-way street (bile from hepatic duct is stored in gall bladder and later expelled to common bile duct to duodenum)

FUNCTIONDigestion--bile is digestive enzymes plus RBC breakdown productRemoves nutrients and toxins from blood (hepatic portal system brings gut blood directly to liver)Glucose metabolism (with pancreas--see below)

REVIEW: General blood supply to gut--ventral branches off of aorta

Celiac a.--to stomach, liver, pancreas, spleen, duodenumSuperior (cranial mesenteric a.--to small intestines and most of colonInferior (caudal) mesenteric a.--to descending colon, rectum

REVIEW:Liver: Blood Supply

Hepatic Veinfrom inferior vena cava

Brings O2 blood

Hepatic Portal VeinCarries nutrient-rich blood from stomach + intestines to liver

Portal system = 2 capillary beds!

pg 660

Pancreas

STRUCTURESmaller, diffuse glandHead in C of duodenumTail extends towards spleen

FUNCTIONDigestion--produces most digestive enzymes of small intestinesGlucose metabolism--Islets of Langerhans

Beta cells make insulinAlpha cells make glucagon

Following a meal, with nutrients flowing into blood from gut

Insulin produced by Beta (B) cells of pancreaseReleased following a mealInsulin stimulates cells to take up (diffuse in) glucoseGlucose can be stored as glycogen in liver, muscle tissueGlucose is used for cellular respiration, or converted to fatty acids in other cells

INSULIN

Between meals, with no nutrients flowing into blood from gut

Glucagon produced by Alpha (A) cells of pancreaseReleased between mealsGlucagon stimulates breakdown of glycogen into glucose by liver cellsGlucagon stimulates adipose tissue to break down complex lipids into fatty acidsReleased glucose is used for cellular respirationReleased fatty acids can also be used for cellular respiration

GLUCAGON

“How Stuff Works” Diabetes:http://www.howstuffworks.com/diabetes1.htm

Liver receives blood from intestines (don’t forget hepatic portal systemAfter meal, in response to insulin from pancreas, glucose stored as complex carbohydrate--glycogen--in liverBetween meals, in response to glucagon from pancreas, glucose is releasedPancreas releases insulin when sugar levels in blood go upInadequate or zero insulin production results in hyperglycemia or high blood sugarOverproduction or over-dosing of insulin results in hypoglycemia or low blood sugar--insulin shock

Glucose metabolism review

Type I DiabetesBeta (B) cells of pancreas Islets of Langerhans are destroyedProbably “auto-immune”—body’s own immune system destroys cellsNo insulin is producedSo, “starvation amid plenty” Child eats more and more, but body starts to use fat and eventually muscle protein as a nutrient source. Without treatment, children become seriously emaciated.Treatment is using exogenous insulin (injected or from pump) If insulin dose is too high, blood sugar falls leading to “insulin shock”—quick sugar dose will help re-establish sufficient sugarIf insulin dose is too low, sugar levels will be high, leading to lethargy (short-term), and long-term complications of small vessel disease (usually in kidney, retina and extremities)Regular exercise helps keep sugar levels low, promote efficient and more regulated use-pattern for insulin

Cells become “resistant” to insulinPancreas Beta-cells overworked trying to provide sufficient insulin so cells can use glucoseObesity means larger body mass with more insulin needs for more cellsLack of exercise leads to inefficient use of insulinGenetic factors also importantClassic case study: Pima Indians

Type II Diabetes

Pima Indians and DiabetesPima Indians and BreastfeedingPima study to justify low carb diet?

“Traditional” and “Modern” Diets

The case for Food: What’s the problem?(and are we on the road to a solution?)

We understand what cells needWe understand how digestion worksWe know all the minor elements—vitamins and minerals—that seem to be essentialWhy are we in a nutrition crisis?What’s wrong with the nutritionist viewpoint?Why are nutrition-related lifestyle diseases like diabetes and cardio-vascular problems rising at epidemic rates?Can science alone guide people’s eating habits?

How do people decide what to eat?

Cultural and commercial influences govern what people eatGovernment policies influence how food is grown and distributedIn U.S., commercial interests are overtaking cultural heritage in influencing decisions about what to eatRESULTS:

Typical dinner plate item has traveled 1500 milesPackaged and processed food dominate in dietLoss of art of cooking, cuisineAbundance of cheap corn and soy-based processed food packaged for easy commercializationControl of food production and distribution by large corporationsSmall farmer cannot compete with subsidized mass-market pricesUse of nutritionism to justify production and commercialization of food products: “vitamin fortified,” “low-fat,” “heart-healthy” etc.Loss of knowledge of how to produce food, or even where food comes from.

REMEDY—win-win-win. Remember food?

Food and Nutrition

Remember food?

Bring a spiritual and cultural base back to our diet

Bring long-term health to our lives

Bring long-term health to our farming and agricultural ecosystems

Positive solutions to the nutritionism bamboozleThe Win-Win-Win approach

What is the cultural base for our diet?What is U.S. cuisine?

U.S. cuisine may be more defined by imports—what immigrants have brought—as is much of U.S. culture.Commercial interests—packaged food, fast food, large-scale agriculture—strive (very successfully) to replace cultural food base.Most of us do have a cultural food base—whatever we call “home-cooking” is usually it.This cultural base varies from region to region, neighborhood to neighborhood and even household to household.But usually most of the raw ingredients can be obtained locally.Home-cooking with fresh local ingredients is what most often stirs people’s souls.

What is a healthy diet?

Diets that are advertised as healthy probably are not.The nutritionism approach usually doesn’t work since it is home-cooked FOOD, not nutrients that inspire people to eat well.Most culturally-based cuisines have a natural mix of nutrients that have worked for hundreds or thousands of years to keep their cultures healthyIncreased societal wealth, in today’s world, causes what is known as the “nutritional transition” taking people away from their cultural base, and into the fast-paced world of prepared foods in colorful packages and under brand-name marketing. What is healthy? Non-packaged; local; home-cooked; culturally-based; spiritually satisfying.Can a culturally-based, home-cooked cuisine be made more healthy? Of course—this is the right role for the nutrition approach.

How is food raised?What is a healthy agro-ecosystem?

Most food is no longer farmed, but factory-produced.Factory food production looks for maximum short and medium-term profit.Factory food production is unconcerned with long-term health of the consumer, or long-term productivity of the landFactory food production is responsive only to government regulations, not to local prestige. Many people in the U.S. no long know where their food comes from, or even how food is grown and raised, or how to do it themselves.Small farmers survive by growing local prestige which comes from their concern for long-term health and satisfaction of the consumer and long-term productivity of the land. It is increasingly difficult for them to make a profit.

The Food Satisfaction Triangle

Locally and Sustainably Grown Food(small farmers)

Spiritual and Cultural Base for Diet(home-cooked)

Healthy, Satisfied, Longer Lives

(minimal lifestyle diseases—obesity, diabetes, cardio-

vascular)