Figure 1. Structure of Villus AmylaseProteaseLipase Example of this Enzyme Source Substrate Products Optimum pH AmylaseProteaseLipase Example of this.

Human Health and PhysiologyMs. Scott J205

Digestion

Digestion Assessment Statements• Explain why digestion of large food particles are essential.• Explain the need for enzymes in digestion.• State the source, substrate, products, and optimum pH for

amylase, protease, and lipase.• Draw and label a diagram of the digestive system.• Outline the function of the stomach, small intestine, and large

intestine.• Distinguish between absorption and assimilation.• Explain the structure of the villus is related to its role in

absorption and transport of the products of digestion.• https://www.youtube.com/watch?v=b20VRR9C37Q

Digestion of Food • Mouth and the

Esophagus• Absorption • Assimilation

Figure 1. Structure of Villus

Need for Digestion Amylase Protease Lipase

Example of this

Enzyme

Source

Substrate

Products

Optimum pH

• Food we consume are substances that are made by other organisms• Molecules in food are to

large to absorb • Diffusion and Facilitated

Diffusion • Active Transport

• Body Temperature and Enzyme Activity

Amylase Protease Lipase

Example of this

Enzyme

Salivary Amylase

Pepsin Pancreatic Lipase

Source Salivary Glands

Wall of Stomach

Pancreas

Substrate Starch Proteins and

peptides

Triglycerides

And phospholipi

ds

Products Maltose Small Polypeptide

s

Fatty Acids and

Glycerol

Optimum pH

7 1.5 7

Pancreatic Juices• The pancreas secretes

enzymes into the lumen of the small intestine.• Secrete hormones insulin

and glucagon into the blood.• Synthesizes and secretes

digestive enzymes into the gut.

Figure 2. Intestinal Structure

Pancreatic Juices• Synthesized in pancreatic

gland on ribosomes on the RER.• Processed in the Golgi

Apparatus • Ducts form one large

pancreatic duct • 1 liter/day secreted in the

lumen of the small intestine Figure 3. Arrangement of cells and ducts in a

part of the pancreas that secretes digestive enzymes

Structure of the Digestive System Structure Function

Mouth Voluntary Control of Eating . Mechanical digestion of food by chewing and mixing with saliva, which contains lubricants and enzymes that start starch digestion.

Esophagus Movement of food by peristalsis from the mouth to the stomach

Stomach Churning and mixing with the secreted water and acid which kills foreign bacteria and other pathogens in food, plus initial stages of protein digestion.

Small Intestine Final stages of digestion of lipids carbohydrates, proteins, and nucleic acids, neutralizing stomach acid, plus absorption of nutrients.

Pancreas Secretion of lipase, amylase and protease

Liver Secretion of surfactant in bile to break up lipid droplets

Gall Bladder Storage and regulate release of bile

Large Intestine Reabsorption of water, further digestion carbs by symbiotic bacteria , plus formation and storage of feces.Figure 4. The Human Digestive

System

Have You Ever Wondered ???• What would happen to the

normal function of the digestive tract if part of one of the following organs were removed or greatly reduced in size ( for example, as a result of a surgery or accident)? How would a person’s eating habits need to be changed to accommodate reduction in size ?• https://

www.youtube.com/watch?v=Wu2iJseYlOQ

Peristalsis • Peristalsis –the contraction of circular and

longitudinal muscles layers from the esophagus to the small intestine mixes the food with the enzymes and moves it along the gut

• Wave-like motion• One Direction – away from the mouth• Enteric Nervous System – controls unconscious

contraction of food. • Process time

• Swallowed food moves quickly down the esophagus to the stomach

• In the intestines the food is moved at a slower progression, only a few centimeters at a time.

• Main function in the intestine is churning of the semi-digested food to mix it with enzymes and thus speed up the process of digestion.

Figure 5. Peristalsis movement from esophagus to small intestines

Digestion In Small Intestine • Enzymes digest most

macromolecules into monomers for food in the small intestine• Wall of small intestine

• Nuclease• Maltase • Lactase• Sucrase• Exopeptidases and

Dipeptidases

• Duration of Digestion Figure 6. Detail structure of the small intestine

Structure of the Wall of the Small Intestine

Four layers of living tissues from outside moving inwards

• Serosa – Outer coat

• Muscular layers – longitudinal muscle and circular muscle

• Sub Mucosa – a tissue containing blood and lymph vessels

• Mucosa – lining of the small intestine, with the epithelium that absorbs nutrients on the inner surface

Villi and the Surface Area for Digestion

• Villi increase the surface area of the epithelium over which absorption is carried out.• Absorption – the process of

taking substances into the cells and the blood• Rate of absorption • Adult: 7 meters long and

25 -30 millimeters wide with fold in the inner surface

• Inside the intestinal wall Figure 7. Structure of the an intestinal villus

Villi and the Surface Area for Digestion • Small finger like

projections of the mucosa.• Size: 0.5 and 1.5 mm

long • Increase surface area by

factor of 10.

Figure 8. Scanning electron micrograph of villi in small intestine

Absorption by Villi• Villi absorbs monomers formed by digestion as well as

mineral ions and vitamins• The epithelium that covers the villi must form a barrier to

harmful substances, while at the same time being permeable enough to allow useful nutrients to pass through.

• Villus absorb these products of digestion of macromolecules in food.• Glucose, fructose, galactose, and other monosaccharides• Any of the twenty amino acids used to make protein • Fatty acids, monoglycerides, and glycerol • Bases from digestion of nucleotides

• Also absorb substances required by the body and present in foods but not needing digestion:• Mineral ions such as calcium, potassium and sodium• Vitamins such as ascorbic acid (vitamin C)

Methods of Absorption• Different methods of

membrane transport are required to absorb different nutrients.• Simple Diffusion• Facilitated Diffusion• Active Transport • Exocytosis

Figure 9. Example of methods of absorption in the small intestine

Methods of AbsorptionExample 1 Lipid Absorption• Fatty acids and monoglycerides

can be absorbed into the villus of epithelium by simple diffusion • Fatty acids are also absorbed in

the microvilli by facilitated diffusion via fatty acid transporters• Triglycerides are reformed and can

not diffuse back into lumen• Form lipoproteins that are then

released by exocytosis through the plasma membrane• Carried away in lymph or enter the

blood capillaries in villi

Figure 10. Lipid Absorption

Methods of AbsorptionExample 2 Glucose Absorption• Glucose uses active transport, sodium

potassium pumps, from the cytoplasm to the interstitial spaces inside the villus.

• With facilitated diffusion (passive, depends of concentration gradient) sodium-glucose co-transport protein in the microvilli transfer sodium ion and glucose molecule together from the intestinal lumen to cytoplasm of epithelial cells.

• Facilitated diffusion also enables glucose to pass through the glucose channels from the cytoplasm to the interstitial spaces inside the villus into the blood capillaries.

Figure 11. Glucose Absorption

Final Destinations of Digestion Products

•Starches bloodstream

•Fats lymph vessels (lacteals)

•Proteins bloodstream

HHP Digestion – Assignment #1 Due 9/11 A and 9/12 B (Typed Response with references)• Tapeworms sometimes infect humans, anchoring themselves to the wall of the small

intestines. Based on how digestion is compartmentalized along the mammalian alimentary canal, what digestive functions would you expect these parasites to have?

• A single sandwich is likely to contain carbohydrates, lipids, and proteins. From a biochemical viewpoint, what will happen to each molecule of digestion?

• You ingest glucose molecule in the starch of a breakfast cereal. State as many specific locations as you can for this single glucose molecule from the time it is in your mouth to the time it enters a muscle cell of your right forearm.

• Lastly, Using materials you provide from home, create a labeled model of all digestive system structures beginning with the mouth and ending with the anus.  Focus on the materials used to demonstrate the physical structure of each organ or tissue.  Be sure to include the accessory organs too! (Rubric on next slide)

Assignment # 1 Rubric CATEGORY               4 = A               3 = B               2 = C                 1= D

Assignment #1: Digestion Diagram

Diagram or model has all of the following: -structures present -materials are creatively linked to the original structure -final product is neat and well organized - shows thought and a clear understanding of the digestive process (score x6)

Diagram or model has 3 of the following: -structures present -materials are creatively linked to the original structure -final product is neat and well organized - shows thought and a clear understanding of the digestiveprocess (score x6)

Diagram or model has 2 of the following: -structures present -materials are creatively linked to the original structure -final product is neat and well organized - shows thought and a clear understanding of the digestiveprocess (score x6)

Diagram or model has 1 of the following: -structures present -materials are creatively linked to the original structure -final product is neat and well organized - shows thought and a clear understanding of the digestive process (score x6)

HHP Digestion – Assignment #2 Due 9/18 A and 9/19 BProblems with the Digestive System• Choose a specific problem with the digestive system from the list below.  Create an

interactive poster on Glogster – (http://edu.glogster.com/) designed to educate patients with that disorder to be given to the school nurse to share with other students.

Information that must be included in your Glog:• Describe the Problem • Causes• Symptoms• Treatments• Those affected (if applicable) • Questions with answers to age appropriate questions concerning this disorder• Age appropriate diagrams and videos that help explain this disorder (at least one of

each)Choices of Digestive Disorders:• Anorexia, Alactasia (lactose intolerance), achalasia, Anal fistula, Appendicitis, Bulimia,

Diverticulitis, gastric ulcer, Celiac disease, constipation, diarrhea, Cholelithiasis (gall stones),Esophageal reflux, Hiatal hernia, gastritis, ileus, colorectal cancer, hepatitis, cholecystitis, IBS (irritable bowel syndrome), pancreatitis, Crohn’s disease, volvulus, or an approved digestive problem of your choice.  (Rubric on next slide)

Assignment # 2 Rubric

CATEGORY               4 = A               3 = B               2 = C                 1= DAssignment #2: Problems with the Digestive System

-Source information is clear for all content -Makes excellent use of font, color, graphics, effects, etc. to enhance Glog -Covers topic in depth with details and examples -Subject knowledge is excellent -Met all requirements and exceeded -Excellent Spelling and Grammar (score x7)

-Source information collected for all content with few errors -Makes excellent use of font, color, graphics, effects, etc. to enhance Glog -Covers topic and subject area knowledge appears to be good -All requirements are met -Few spelling and grammatical errors (score x7)

-Source information collected for all content with some errors -Makes use of font, color, graphics, effects, etc. but some distract from Glog content -Covers topic and subject area with a few errors -One or two requirements are not met -Few spelling and grammatical errors (score x7)

-Very little or no information collected for all content with many errors -Makes use of font, color, graphics, effects, etc. but some distract from Glog content -Covers topic and subject area with a few errors -Two or more requirements are not met -Multiple spelling and grammar errors (score x7)

HHP Digestion – Assignment #3 Due 9/18 A and 9/19 B

Assignment #3: A Day in the Life

• Using the digestive disorder studied in Assignment #2, write a one-page diary entry, in first person, reflecting on what it would be like to have this disorder.  How does this disorder affect daily life?  How does it affect what is eaten?  What is done to overcome the symptoms of this disorder?  How does it affect your interaction with others?  How does it affect your overall mood and behavior? 

• The diary entry must be submitted in Microsoft Word using 1 inch margins, 12 point, Times New Romans Font, double spaced, and heading the paper with the title and your name.  Use spell and grammar check before submitting. (Rubric on next slide)

Assignment # 3 Rubric

CATEGORY               4 = A               3 = B               2 = C                 1= DAssignment #3: A Day in the Life - Diary Entry

Narrative has all requirements-Creative -Focused on assignment story -Clear organization -Excellent Spelling and Grammar (score x5)

Narrative is missing one requirements-Creative -Assignment story is apparent -Good organization - One or two spelling and grammar errors (score x5)

Narrative is missing some requirements -Lacks creativity -Assignment story is missing connection to person -Lacks organization - Many spelling and grammar errors (score x5)

Narrative is missing requirements -Lacks creativity -Assignment story lacks empathy - Lacks organization - multiple spelling and grammar errors (score x5)

That’s All Folks !!!