1. At times the level of glucose rises above the set point

2. When this happens the pancreas secretes insulin into the blood.

3. Insulin opens the gated channels for glucose on all body cells and triggers the liver to store glucose as glycogen. As a result, the blood glucose drops

4. At others times, the glucose level falls below the set point.

4. At others times, the glucose level falls below the set point. Which triggers the pancreas to release glucagon.

5. Glucagon causes the glucose transport proteins to close and triggers the liver to convert glycogen to glucose.

6. Blood glucose rises

Mutant gene for appetite

The average American diet is too high in refined carbohydrates but so low in complex carbohydrates that it is too low in total carbohydrates. The average American diet is too low in fiber and too high in fat and proteins. The best ratio according to most nutritionists is:

50% carbohydrates by % of calories30% proteins by % of calories 20% fats by % of calories

However, there are:4 Kilocalories/g in carbohydrates4 Kilocalories/g in proteins9 Kilocalories/g in fats

CarbohydratesCarbohydrates are a major source of energy and should account for 50% to 60% of calories consumed each day. Sugars:• monosaccharides and disaccharides • Sources: found in fruits (sucrose, glucose, fructose, pentose), milk (lactose), and soft drinks and sweets. Complex Carbohydrates:• polysaccharides • Sources: found in whole grain cereals, flour, bread, rice, corn, oats, potatoes, and legumes. 

• Protein should account for 10% to 20% of the calories consumed each day. Protein is essential to the structure of red blood cells, for the proper functioning of antibodies resisting infection, for the regulation of enzymes and hormones, for growth, and for the repair of body tissue.Protein sources:• Amino acids are the building blocks of protein and are found in a variety of foods. Meat, milk, cheese, and egg are complete proteins that have all the essential amino acids. Other sources of protein include whole grains, rice, corn, beans, legumes, oatmeal, peas, and peanut butter. For vegetarians, vegans and/or those who do not eat meat, fish, eggs, or dairy products, it is important to eat a variety of these other foods in order to get enough protein.

Fat should account for 30% or less of the calories consumed daily, with saturated fats accounting for no more than 10% of the total fat intake. Fats are a concentrated form of energy which help maintain body temperature, and protect body tissues and organs. Fat also plays an essential role in carrying the four fat-soluble vitamins: A, D, E, and K.

Excess calories from protein and carbohydrates are converted to and stored as fat. Even if you are eating mostly "fat free" foods, excess consumption will result in additional body fat. Fat calories in food are readily stored, while it takes energy to transform protein and carbohydrates to body fat. The only proven way to reduce body fat is to burn more calories than one consumes.

Saturated Fat:• Function: tends to increase blood cholesterol levels. • Sources: found mostly in meat and dairy products, as well as some vegetable oils, such as coconut and palm oils (tropical oils). Butter is high in saturated fat, while margarine tends to have more unsaturated fat. Most saturated fats tend to be solid at room temperature, with the exception of tropical oils.Polyunsaturated Fat:• Function: tends to lower blood cholesterol levels• Sources: found mostly in plant sources. (safflower, sunflower, soybean, corn, cottonseed)Monounsaturated Fat:• Function: tends to lower LDL cholesterol (the "bad" cholesterol)• Sources: found in both plant and animal products, such as olive oil, canola oil, peanut oil, and in some plant foods such as avocado

Giraffe eating bones to obtain phosphorus

Suspension-feeding

Substrate-feeding

Fluid-feeding

Bulk-feeding

Intracellular Digestion

ExtracellularDigestion and then phagocytosis and Intracellular

Various alimentary canals

sphincter

ileocecal sphincter

anal sphincter

Oral sphincter

Slide 139Tongue

Fungiform papillae (taste buds)

body wall

parietalperitoneum

visceralperitoneum

digestivetract wall

mesenteryartery vein

Slide 143Esophagus

Lu-lumen

Mu-mucosa

Su-submucosa

Me-muscularous

externa

Ad-serosa

Slide 144

Esophagus

SS-stratified squamous

LP-lamina propria

MM-muscularis mucosa

Su-submucosa

ME-muscularis external

Ad-serosa

Rugae

Slide 147Stomach

-openings to gastric glands

Rugae

GG-gastric glands

LP-lamina propria

Ca-capillary

Slide 146Stomach

CM-circular muscles

LM-longitudinal muscles

Slide 150Stomach

Fig.1 PC-parietal cells

IC-intracellular canaliculus

ZC-chief cells

Fig.2 M-mitochondria

Fig.3 cell that secretes

gastrin

zymogens in the small intestine

HCl

Pepsinogen pepsin

enteropeptidase

trypsinogen trypsin

trypsin

procarboxypeptidase carboxypeptidase

trypsin

chymotrypsinogen chymotrypsin

zymogens must be secreted in an inactive form and then be activated

Slide 151Small Intestine

DuodenumNo folds in

submucosa because this is from rat a

Vi-villi

Slide 154Small Intestine

Jejunum Fig.2-openings to

intestinal glands

MF-microfolds

Fig.3 AC-absorptive cells; GC-goblet cells

Fig.4 resin cast of the capillaries in a single villus

lacteal

Absorption of nutrientsGlucose-facilitated diffusion & active transport amino acids-active transport & FDglycerol & fatty acids-diffusionvitamins and minerals-active transport

Slide 156Small Intestine

JejunumFig.1&2

Mv-microvilli on a goblet cell are shorter than

MA-microvilli on absorptive cells

Fig.3 MG-mucus granules in a goblet cell

Fig.4 BL-basement membrane

Slide 161Colon

TG-tubular glands

Slide 163Colon

Fig.1 Su-folds in submucosa

ME-muscularis mucosa

Fig.2 Op-opening to tubular glands that are filled with mucus

BM-basement membrane

Large Intestine