Pancrease and Glucose Regulation Diabetes frames the debate

Pancrease and Glucose Regulation Diabetes frames the debate? Cells need sugar—ATP and the Krebs Cycle Other nutrients Role of liver in processing nutrients, storing glucose Role of pancreas (as endocrine organ) in controlling sugar levels in the blood via insulin and glucagon secretion Metabolic pathways after meal (absorptive) and between meals (post-absorptive) Type I Diabetes Type II Diabetes and Pima Indians The case for Food

Diabetes mellitus—”starvation amidst plenty” Type I Juvenile 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 Glucose All cells of body need constant glucose supply, especially nervous tissue Most other nutrients can be converted into glucose or derivatives for making ATP 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 Acids Only 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 Nutrients Almost everything we eat can be converted and used by Kreb’s cycle

Why not eat just sugar? 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

What keeps sugar constantly available in blood? Immediately after a meal, nutrients are flowing into blood across wall of stomach, small intestines Between meals, when food has mostly been digested, nutrients are not available Nonetheless, blood sugar levels are kept virtually constant How is this possible? Role of liver in temporary storage of glucose as glycogen Differences in “absorptive” and “post-absorptive” metabolic pathways Role of pancreas as enodcrine organ to release insulin (Bcells of islets) and glucon (A-cells of islets) to regulate process

Liver and Pancreas

REVIEW: Liver STRUCTURE Large ventral organ of abdominal cavity with multiple lobes (learn them!!) Sets against inferior surface of diaphragm on left side Forms as outpocketing of gut--common bile duct is left as connection Bile duct is two-way street (bile from hepatic duct is stored in gall bladder and later expelled to common bile duct to duodenum) FUNCTION Digestion--bile is digestive enzymes plus RBC breakdown product Removes 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, duodenum Superior (cranial mesenteric a. --to small intestines and most of colon Inferior (caudal) mesenteric a. --to descending colon, rectum

REVIEW: Liver: Blood Supply Hepatic Vein from inferior vena cava Brings O 2 blood Hepatic Portal Vein Carries nutrient-rich blood from stomach + intestines to liver Portal system = 2 capillary beds! pg 660

Pancreas STRUCTURE Smaller, diffuse gland Head in C of duodenum Tail extends towards spleen FUNCTION Digestion--produces most digestive enzymes of small intestines Glucose metabolism--Islets of Langerhans Beta cells make insulin Alpha cells make glucagon

Following a meal, with nutrients flowing into blood from gut

INSULIN Insulin produced by Beta (B) cells of pancrease Released following a meal Insulin stimulates cells to take up (diffuse in) glucose Glucose can be stored as glycogen in liver, muscle tissue Glucose is used for cellular respiration, or converted to fatty acids in other cells

Between meals, with no nutrients flowing into blood from gut

GLUCAGON Glucagon produced by Alpha (A) cells of pancrease Released between meals Glucagon stimulates breakdown of glycogen into glucose by liver cells Glucagon stimulates adipose tissue to break down complex lipids into fatty acids Released glucose is used for cellular respiration Released fatty acids can also be used for cellular respiration

“How Stuff Works” Diabetes: http: //www. howstu ffworks. com/diabet es 1. htm

Glucose metabolism review Liver receives blood from intestines (don’t forget hepatic portal system After meal, in response to insulin from pancreas, glucose stored as complex carbohydrate--glycogen--in liver Between meals, in response to glucagon from pancreas, glucose is released Pancreas releases insulin when sugar levels in blood go up Inadequate or zero insulin production results in hyperglycemia or high blood sugar Overproduction or over-dosing of insulin results in hypoglycemia or low blood sugar--insulin shock

Type I Diabetes Beta (B) cells of pancreas Islets of Langerhans are destroyed Probably “auto-immune”—body’s own immune system destroys cells No insulin is produced So, “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 sugar If 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

Type II Diabetes Cells become “resistant” to insulin Pancreas Beta-cells overworked trying to provide sufficient insulin so cells can use glucose Obesity means larger body mass with more insulin needs for more cells Lack of exercise leads to inefficient use of insulin Genetic factors also important Classic case study: Pima Indians

“Traditional” and “Modern” Diets Pima Indians and Diabetes Pima Indians and Breastfeeding Pima study to justify low carb diet?

The case for Food: What’s the problem? (and are we on the road to a solution? ) We understand what cells need We understand how digestion works We know all the minor elements— vitamins and minerals—that seem to be essential Why are we in a nutrition crisis? What’s wrong with the nutritionist viewpoint? Why are nutrition-related lifestyle diseases like diabetes and cardiovascular 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 eat Government policies influence how food is grown and distributed In U. S. , commercial interests are overtaking cultural heritage in influencing decisions about what to eat RESULTS: Typical dinner plate item has traveled 1500 miles Packaged and processed food dominate in diet Loss of art of cooking, cuisine Abundance of cheap corn and soy-based processed food packaged for easy commercialization Control of food production and distribution by large corporations Small farmer cannot compete with subsidized mass-market prices Use 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. Remember food?

Food and Nutrition Remember food?

Positive solutions to the nutritionism bamboozle The Win-Win approach 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

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 homecooked 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 healthy Increased 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 land Factory 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) Healthy, Satisfied, Longer Lives (minimal lifestyle diseases— obesity, diabetes, cardiovascular) Spiritual and Cultural Base for Diet (home-cooked)