UNIT 3 - DIGESTIVE SYSTEMDigestion is the mechanical and chemical digestion of food into smaller components that are more easily absorbed into the bloodstream . Each of these components has a certain end task that is necessary for the body to function. The digestive system involves many organs and structures, that work together to complete 4 main functions.

1. Ingest food

2. Break down food into a form that can be used by the body. (amino acids, glucose, fatty acids, etc)

1

3. Absorb and transfer nutrients to blood stream to be carried to other cells of the body

4. Eliminate waste The system works in conjunction with the endocrine, circulatory, respiratory and nervous system to maintain homeostasis.Digestion takes place in two ways. Both methods are used in different parts of the digestive system but both have the same end goal; to increase surface area. The larger the surface area, the faster digestion can proceed.

1. Mechanical digestion (mastication/chewing). This process breaks down food into smaller pieces through mechanical means like biting

2

and grinding. Eg. chewing a piece of carrot into smaller pieces.

2. Chemical digestion – This process breaks down food using enzymes and chemicals to change complex molecules into simple molecules that can be absorbed into blood stream.Eg. Breads (starch)

monosaccharides

The main nutrients that we acquire from food are:

1. Carbohydrates --- break down into monosaccharides

3

2. Fats/Triglycerides ----- break down into 1 glycerol and 3 fatty acids

3. Protein ---- break down into amino acids

4.Water – needed for metabolic processes and makes up 60-80% of body

5. Minerals – inorganic substances (eg. calcium, iron, etc )

6. Vitamins –organic substances (vit C, Vit B, Vit E, etc)

4

FOOD JOURNEY THROUGH THE ALIMENTARY CANAL

Alimentary Canal – This is the pathway that food follows from the mouth to anus. It’s 9 – 11 meters long. This pathway begins at the mouth esophagus stomach small intestine large intestine anus .

MOUTH has 3 main functions1) Mechanical digestion of food takes place here with the help of the teeth .

5

Incisors are used for biting, canines for tearing and molars for grinding. The longer you chew your food the smaller the pieces will become which will help the body digest the food faster. The larger the surface area the easier the chemical digestion will be.

http://education.abc.net.au/home#!/media/2628955/role-of-smell-in-taste

2) Chemical digestion also begins inthe mouth. The mouth contains salivary glands which release saliva to help

6

break down food into smaller chemical units.

There are three salivary glands – parotid, sublingual and submandibular .

Saliva is made up of three components.

a) Water – which helps to moisten the food and dissolve it

b) Mucus – for lubrication of the food for swallowing.

c) Salivary amylase (ptyalin) – enzyme that breaks down carbohydrates (polysaccharides) into disaccharides

7

3) Swallowing – the mouth helps to move food down the esophagus.

Once the food has been chewed and mixed with saliva it forms a ball, which we call a bolus. The bolus will be pushed by the tongue to the back of the throat (pharynx).The soft palate and the uvula will elevate and will push up against the back of the pharynx in order to seal off the nasal cavity so no food can enter. Nerve signals are sent to the respiratory center to inhibit breathing. This results in the epiglottis moving to seal off the trachea (windpipe). Food then moves down the

esophagus. 8

https://www.youtube.com/watch?v=pNcV6yAfq-g

If food enters the trachea, it will trigger the cough reflex to remove the food or you may need assistance by administering J thrusts. https://www.youtube.com/watch?v=RYsz2Od5jDQ

9

ESOPHAGUS is a muscular feeding tube, which carries food to the stomach. Its opening is guarded by the esophageal sphincter. A sphincter is a muscular, elastic ring and a one-way VALVE that will spread open when food pushes against it but will close once the food has passed. Sphincters are very important parts of the digestive system because they keep the food moving in one direction - down the alimentary canal.

10

How will the food get down the tube? Can gravity be the cause of this movement?

No. There are two sets of muscles present in the esophagus.

a) Longitudinal muscles run vertically along the esophagus

b) Circular muscles (rings) are present around the esophagus.

These two muscles are responsible for peristalsis . This is the muscular contraction that pushes food down the tube to the stomach. Food is squeezed by the contraction of the circular muscle behind it and the relaxation of the longitudinal muscle in front of the bolus.

11

The inner lining of the esophagus secretes mucus to help lubricate the food and keep it moving down the tube to the entrance of the stomach.

https://www.youtube.com/watch?v=rJS-Kh5wCQU

https://www.youtube.com/watch?v=57icMkc0rIY

http://www.youtube.com/watch?v=o18UycWRsaA

Once the food reaches the stomach it must pass through the cardiac sphincter.The opening to the stomach is a controlled doorway. We need to control

12

the movement of food into the stomach and we don’t want the food to go back up the esophagus after it has been in the stomach. If this does happen, you can experience heartburn or gastro reflux disease. It causes a burning sensation at the base of the breastbone. The burning is a result of the food having been mixed with stomach acids. The lining of the esophagus is not meant to withstand high acid volumes and so pain and tissue damage can result. This back up of food can occur either from a weakening of the sphincter, hiatal hernia, overeating or from too much/too little stomach acid. The stomach cannot

13

take all the food and so there is an overflow into the esophagus.

14

Comprehension Questions1. What are the 4 functions of the

digestive system?Ingest foodBreakdown food into small moleculesAbsorption of nutrients Eliminate waste

15

2. What are the two types of digestion? How are they different?

Mechanical Digestion – breaks down food into smaller pieces by biting and grindingChemical Digestion – breaks down NUTRIENTS into simple molecules using chemicals and enzymes

3. What are the 6 nutrients we get from our food?Carbs, triglycerides/fats, proteins, water, minerals, vitamins

4. What parts make up the alimentary canal? How long is it?9-11 m

16

Mouth, esophagus, stomach, small intestine, large intestine, anus

5. How is mechanical digestion completed in the mouth?

Chew, chew, chew6. Which nutrient is being digested in

the mouth? What enzyme is involved in this digestion process?

Starch is broken down into disaccharides. Enzyme is called salivary amylase (ptyalin).

7. What are the parts that make up saliva?Water, mucus, salivary amylase (ptyalin)

17

8. What is the function of the epiglottis?Seals off trachea when swallowing so it doesn’t go down your trachea and cause you to stop breathing.

9. Describe the process of swallowing. in detail.Bolus is pushed to the back of the throat by the tongue. Upper palate elevates and closes off the nasal cavity. This triggers the respiratory centre to close off the trachea with the epiglottis so food can be diverted down the esophagus.

18

10. What is the name of the tube that carries food to the stomach?

esophagus11. How does food move from the

esophagus to the stomach? Describe in detail. What is this called?

Peristalsis. Muscular contractions of the circular rings pushes food down and the longitudinal muscles relax and allow food to pass by. It continues down the tube until it reaches its destination.

12. What is a sphincter? How does it work? Why is it important in the alimentary canal?One way valve (muscular elastic ring) that opens when food presses against it and closes once food has passed. The sphincter keeps food moving in

19

one direction down the alimentary canal.

13. What is heartburn and what things can cause heartburn?Heartburn is when you have a burning sensation at the base of the breastbone. It is caused by back up of acidic materials from the stomach into the esophagus. Can result from overeating, too much/too little acid, weakening of the sphincter, hiatal hernia.

STOMACH - is a very complex organ with 3 main functions.1) It’s involved in the storage of food until it’s ready to move to the small intestine. This could take 3 - 4 hours.

20

2) Mechanical digestion – The stomach is made up of 3 layers of muscle : longitudinal, circular and oblique . These muscles work together to churn and mix the food (peristalsis) to break it down into smaller pieces. These layers of muscle are protected by a mucous layer that prevents any damage to the muscle.

3) Chemical digestion - The stomach is the site where protein digestion begins. The inner lining of the stomach is folded into wrinkles called rugae. Located in the rugae are the gastric glands which are responsible for producing the main chemical digestor (gastric juice) in the stomach.

21

Gastric Juice - when food enters the stomach, hormones stimulate the gastric glands to produce gastric juice. Gastric juice is made up of three components.

i) HCl or hydrochloric acid HCl has a couple of functions in the stomach. First, it is released to lower the pH in the stomach between 1- 2. The acidic conditions are necessary for the stomach to create pepsin (see below).

Secondly, the HCl kills off any bacteria that is present in foods. Thirdly, HCl breaks down food mechanically.

ii) Pepsinogen – it is an inactive enzyme that combines with HCl and turns into pepsin. Pepsin is the enzyme

22

that will begin protein breakdown into polypeptide chains.

+ HCl

Pepsinogen (inactive portion) Pepsin(inactive)

iii) Mucus – due to the extremely low pH present in the stomach, mucus is needed to protect the inner lining and muscles of the stomach, otherwise the stomach lining can be destroyed. Lowered mucus levels and stress can result in ulcers which cause erosion of the lining of the

23

stomach wall. Usually it is caused by H.Pylori , a bacterial infection.https://www.youtube.com/watch?v=ax2phMXNIIg – ulcer pictures/videosOnce the food is ready to move out of stomach, it has achieved a creamy consistency and this mixture is now called chyme . The pyloric sphincter controls the passage of the chyme into the small intestine. https://www.youtube.com/watch?v=URHBBE3RKEs - stomach digestion https://www.youtube.com/watch?v=ZuJzYYIS9c4 - how does the stomach functionhttps://www.youtube.com/watch?v=_QYwscALNng - baby full digestive system

24

https://www.youtube.com/watch?v=bo2Ape8JHqA – full digestive system videohttps://www.youtube.com/watch?v=SWMWsOXlBwE ulcer

Comprehension Questions1. How is mechanical digestion

completed in the stomach?Longitudinal, circular and oblique muscles churn and mix the food through peristalsis, to breakdown the food into smaller pieces.

2. What nutrient is digested in the stomach?proteins

25

3. What enzyme is responsible for this?pepsin

4. What is gastric juice? What is it made up of? What gland releases it?

Main chemical digestor of stomach. Made up of mucus, pepsinogen, HCl. Released by gastric gland.

5. What 3 functions does HCl serve in the stomach?1-lowers pH to 1-2 to convert pepsinogen to pepsin. Needed for protein digestion2- kills bacteria3 -breaks down down food mechanically

26

6. Why is it important that the stomach has a precursor like pepsinogen instead of pepsin?

So that it doesn’t constantly breakdown proteins (muscles) of the stomach

7. Why is mucus important in the stomach?To protect the stomach muscles/inner lining from the acids.

8. What is the name that we give to food that has completed its processing by the stomach? chyme

SMALL INTESTINE

27

This is a long, muscular tube that is approximately 6 - 7 meters in an average adultFood moves through the intestine by GENTLE peristaltic motion.The small intestine has two MAIN roles: chemical digestion of nutrients and absorption of nutrients into bloodstream. CHEMICAL DIGESTION - all of the remaining digestion of nutrients takes place here with the help of secretions from the intestine, pancreas, gallbladder/liver.

1) Intestinal Juice – when food enters the duodenum (first part of the small intestine), the vagus nerve

28

triggers the epithelial cells in the intestine to secrete this mixture, which contains 3 types of enzymes.

a) Protease/Peptidase – converts polypeptides to amino acids

b) Sucrase/maltase/lactase – converts

disaccharides to monosaccharides

29

c) Nuclease – breaks down DNA and RNA into nucleotides .

This juice is also alkaline which protects the intestinal walls. The mucous layers are not as thick in the intestine as compared to the stomach.*****

30

2) Pancreatic Juice – when food enters the small intestine, a hormone causes the pancreas to secrete pancreatic juice into the duodenum through the pancreatic duct . This juice contains the following:

a) Pancreatic amylaseAn enzyme that breaks down starch to monosaccharides.

b) Trypsin – An enzyme that breaks down polypeptides into amino acids.

c) Lipase – An enzyme which breaks down triglycerides into glycerol and fatty acids.

31

d) Sodium bicarbonate - a base that neutralizes the stomach acid to protect the intestinal walls (because the mucus layer is not very thick here) and so enzymes can function properly. ******

3) Bile – a greenish yellow liquid produced by the liver. It is composed of cholesterol, bile salts and bilirubin. After it’s produced it is stored in the gallbladder.When chyme enters the small intestine, a hormone called cholecystokinin is released by the cells of the small intestine which

32

triggers the gallbladder to release the bile into the small intestine. Bile is deposited into the small intestine through the bile duct . Recall that in our bodies, substances are dissolved in solution that is mostly water. Since water and oil do not mix, we need bile salts to act as an emulsifier, which is a substance that breaks up large fat molecules into smaller droplets . Bile salts have both polar and non-polar ends, which can interact with the fat, creating smaller droplets to break up the fat. This is mechanical digestion that helps to increase surface area.Then the enzyme, lipase can easily breakdown the triglyceride molecules.

33

It’s similar to how dish detergent like sunlight, can separate oil and help with washing dishes.

*****Recall that certain enzymes function best at an optimum pH. Both the pancreatic and intestinal juices set up an alkaline environment because the enzymes in this part of the tract, need a less acidic pH to function best. See table below.

Table II: pH for Optimum Activity Enzyme pH Optimum

34

Lipase (pancreas) 8.0 Trypsin 7.8 - 8.7 Maltase 6.1 - 6.8 Pancreatic Amylase ( 6.7 - 7.0 )

Comprehension Questions1. What are the 2 main functions of

the small intestine?Absorption and chemical digestion

2. Where does most of the chemical digestion occur?

In duodenum of the small intestine

3. Which organs are involved in secreting enzymes for digestion in small intestine?

Pancreas, small intestine, gallbladder35

4. What are the 3 main secretions going into the small intestine? What makes up each secretion?

Pancreatic juice, intestinal juice, bile

Pancreatic Juice – pancreatic amylase, trypsin, lipase, sodium bicarbonate

Intestinal Juice – Protease/Peptidase, sucrose, maltase, lactase, nucleaseGallbladder – Bile,bile salts,

cholesterol, bilirubin5. Why is bile necessary for breaking

down fats? Is this chemical or mechanical digestion?

Because fats are non polar and can’t be dissolved by water. It breaks down the large fat globule into smaller

36

droplets to make it easier for lipase to work. Mechanical digestion.

6. Explain the importance of an alkaline environment in the intestine.

Alkalinity is important in the small intestine because the small intestine doesn’t have a mucous layer to protect from and acid environment and because the enzymes that work in the small intestine work best at an alkaline pH.

ABSORPTION – all digested nutrients are now ready to move to other sections of the intestine to be absorbed in the jejunum and the ileum. These are the last two parts of the small intestine.

37

The lining of the intestine is pleated into folds called plicae, similar to the stomach. The plicae are covered in villi . These are fingerlike projections that protrude out from the inner epithelial layer that help maximize surface area for absorption of nutrients.They are approximately 0.5 – 1 mm long and because of their numbers (10-40 per sqmm), they increase surface area 30 X . Each villus is covered with smaller hair like structures called microvilli that are collectively called the brush border . This increases surface area by 60X . Each villus has a capillary network that is connected to the liver, via the hepatic portal vein. The villus also has a lacteal

38

tube which is connected to the lymph system.Amino acids, monosaccharides, water and electrolytes diffuse into the capillaries and are carried to the liver via the portal vein.Glycerol and fatty acids diffuse into the lacteal tubes which will deposit into the lymph ducts. Later these will be deposited into the bloodstream. *****Villi also physically sway and bend to increase the blood and lymph flow, which speeds up absorption rates. Food remains in the small intestine for 4 – 6 hours to allow for maximum absorption of nutrients. Once it is ready, it moves into the large intestine through the ileocecal valve.

39

40

Comprehension Questions1. Which sphincter controls the

movement into the small intestine?Pyloric sphincter

2. In which part of the small intestine does absorption occur?

Jejunum and ileum3. What structures aid in absorption

of nutrients?villi

4. Why is it so important to have such a large surface area here?we need to absorb all the nutrients that were digested in the small

41

intestine so the more villi, the faster the absorption.

5. Describe the villus structure.The villus is a fingerlike projection 0.5-1 mm, that is lined with epithelial cells and inside has a capillary system directly connected to the liver and a lacteal tube connected to the lymph system through which nutrients can be absorbed. Each villus is covered in microvilli which are collectively called the brush border.

6. How do the broken down nutrients (amino acids, monosaccharide, fatty acids, glycerol) get into the bloodstream?

42

Amino acids and monosaccharides are transported into the capillaries via diffusion. Fatty acids and glycerol are carried into the lacteal tube and later deposited into the blood.https://www.youtube.com/watch?v=Ry-q2gVzB4k - celiac disease

LARGE INTESTINE – a.k.a. the colon

43

This tube is wider and shorter than the small intestine (1.5 m long). It is responsible for the ABSORPTION of water and ELIMINATION of waste.

The chyme moves from the small intestine, through the ileocecal valve and into the cecum which is the first part of the colon.The following things will take place as the remaining chyme moves through the colon via peristalsis:

1) Water, Na+ and vitamins are absorbed back into the body through the walls of the large intestine. If proper absorption of water does not occur then diarrhea occurs. If the

44

feces does not have enough water then the person becomes constipated. (see below) 2) Undigested food is broken down by

bacteria to produce vitamin K and vitamin B12 which are important for body functions. This is done through the process of fermentation. Bacteria is the reason feces is brown and has such a pleasant aroma! We can replenish this “good bacteria” in our gut by taking probiotics or eating yogurt.

3) Mucus is secreted by the cells within the large intestine to facilitate movement of waste material. It acts as lubrication.

4) Remaining undigested food or feces is stored in the rectum until it

45

passes out of the anus through the anal sphincter.

Two sphincters control the movement of feces out of the body. One is under involuntary control. The pressure of the feces pushing against the sphincter triggers reflex relaxation of the sphincter.

The other is voluntary and allows elimination to be controlled or modified. (perhaps for a better time!)

***Diarrhea can be caused by infection, inflammation (allergy) or nervous stimulation. These factors cause an increase in peristalsis of the intestine. This disrupts the water absorption process and the feces moves out with too much water. This can lead to

46

dehydration and disturbances in circulatory system due to imbalance of salts in blood and increase of blood viscosity. There is also loss of “good bacteria”. Severe diarrhea can lead to death.https://www.youtube.com/watch?v=mh90RPA-C10 colonoscopy

How often should we defecate? 1-2X a day!Constipation occurs when bowel movements are very difficult to pass. This could be due to an obstruction in the colon or because of diet low in fiber and water intake. Hormones, medication and heavy metal toxicity can also play a role. This could also be

47

because people do not defecate when the need arises. Natural laxatives can be used in serious cases but are not advised for overuse. Both diarrhea and constipation are SYMPTOMS of underlying problems. They are not diseases.http://en.wikipedia.org/wiki/File:Constipation.JPG

Comprehension Questions1. How do the small and large

intestines compare physically?Large intestine and wider and shorter than the small intestine. There are no villi in the large intestine.

2. What are the main functions of the large intestine?

48

Absorption of water and vitamins, digestion of remaining materials, creation of vitamins, secretion of mucus.

3. Why are bacteria present in the colon?

They will breakdown remaining materials (fibre/carbs) and create vitamin K and B12. Important for proper digestion.

4. Why is mucus important in the alimentary canal?To protect the inner lining of the canal and lubricate the passageway to facilitate movement of stool.

49

5. Explain how the body controls movement of feces through the anus.

Two sphincters. One is involuntary and one is voluntary. As food presses against it the muscles send a message to the brain to allow for the sphincter to open. You control the voluntary one and can control when you will pass your stool.

ACCESSORY ORGANSThese organs are part of the digestive system but are not part of the alimentary canal because food does not

50

pass through them. These organs are necessary because they aid the digestive process . PANCREAS – This is a glandular organ situated near the stomach with digestive and endocrine roles.

1) produces pancreatic juices for digestion in the small intestine.

2) produces the hormones insulin and glucagon to control blood sugar levels. Insulin – converts glucose in blood into glycogen to be stored in the liver Glucagon – converts glycogen in liver into glucose and releases it into blood.

51

In order to maintain homeostasis, blood glucose levels must be kept at 100 mg/ml. The pancreas and liver control blood sugar levels through a negative feedback pathway. If the blood has high levels of glucose, (for example you drank an extra large slurpee!!) the nervous system triggers the pancreas to produce insulin. The insulin triggers the liver to convert all the extra glucose into

52

glycogen, which will be stored in the liver. If glucose levels are too low, the nervous system triggers the pancreas to release glucagon , which triggers liver to convert glycogen into glucose , which will be released into the blood. Once glucose levels have returned to normal, the hormones will stop being released.What happens when this system fails? Diabetes.https://www.sciencenews.org/article/artificial-insulin-releasing-cells-may-make-it-easier-manage-diabetes?tgt=nr

53

Negative Feedback Pathway – Liver and Pancreas

LIVER - is the largest glandular organ of the body weighing about 3 lb (1.36 kg). It is reddish brown in color and is divided into four lobes.

Blood is carried to the liver via two large vessels called the hepatic artery and the portal vein. The hepatic artery carries oxygen-rich blood from the aorta .The portal vein carries blood containing digested nutrients, toxins, minerals, vitamins from the small intestine .

54

Liver has over 500 functions. Some include:

1) produces bile for fat digestion

2) works in conjunction with pancreas to control blood sugar, stores glycogen.

3) detoxifies or cleans the blood

4) stores iron, copper and fat soluble vitamins like A, D, E, B12 and K

5) produces urea (the main 55

substance of urine)

6) makes certain amino acids and proteins

7) produces about 80% of the cholesterol in your body

8) metabolizes amino acids, carbs and fats

Disease of the liver include cirrhosis, hepatitis, liver cancer https://www.youtube.com/watch?v=l-SBR7p7K-M - liver cirrhosis

GALLBLADDER – a small muscular, hollow sac that stores concentrated bile produced by the liver . The adult

56

gallbladder stores approximately 50 ml bile. It is triggered by CCK (hormone), to release bile via bile duct. It can be damaged by the development of gallstones , which are formed by hardened bile.

http://www.lookgreat-loseweight-savemoney.com/liver-flush.html

APPENDIX – a small wormlike structure that extends from the cecum of the large intestine.

57

Once thought to be a useless organ, scientists have discovered it may play a role in immunity and storage of good intestinal bacteria . It can become infected or inflamed resulting in appendicitis. It could be the cause of an over reactive immune system or infection due to undigested food becoming lodged in the appendix.If it is inflamed, fluid levels may rise and the appendix could burst releasing toxic wastes into the system. This could cause peritonitis – an infection of the abdominal lining and result in death. Therefore it is often removed to protect the rest of the body.

58

VITAMINS AND MINERALSThese are nutrients that must be obtained from foods we eat because they are not produced by the body, except for vit K and vit B12.

A lack in vitamins or minerals can result in complications.

59

Body absorbs vitamins and minerals better from food than from supplements because they are in their most natural form.VITAMINS are organic compounds that must be obtained through food because most are not produced by the body.They are important for metabolic purposes in the body. They can also be portions of coenzymes or precursors of enzymes.13 vitamins exist. They are organized into 2 groups. Water soluble (C, B1/thiamine, B2/riboflavin, niacin, folic acid, vit b6, pantothenic acid, vitamin B12, biotin. Fat soluble (vit A, D, E, K (not potassium)

60

MINERALS are inorganic substances that are each involved in very specific reactions in the body. Minerals are organized into two groups.Macrominerals – needed in larger quantities by the body. Recommended daily allowance (RDA) is more than 100 mg. (Ca, P, K, Na, Cl, Mg)Microminerals – or trace minerals. Needed in smaller quantities. RDA is less than 20 mg. (Zn, Fe, F, Cu, I)

61

62

DIGESTION UNIT REVIEW – review all the comprehension questions

Terms to know

mechanical digestion gastric juice heartburnchemical digestion pepsinogen pepsinlipasealimentary canal emulsificationesophagus protease diarrheaperistalsis trypsin constipationepiglottis nuclease cardiac sphinctersodium bicarbonatepyloric sphincter pancreatic juiceanal sphincter sucrase stomachmaltase pancreas lactaseliver bile salts large intestine/colon cholecystokinin small intestine plicaerugae duodenum villichime jejunum brush borderbolus ileum hormonespancreatic duct rectum vagus nervebile duct gallbladder insulinptyalin/salivary amylase salivary glands glucagonsaliva gastric glands mucusappendix cecum

1. What are the 4 functions of the digestive system?

2. What are the 6 main nutrients acquired from food?

3. Distinguish between mechanical and chemical digestion. Know where each type of digestion occurs in the digestive system.

4. What are the parts of the alimentary canal?

5.. What is the general structure of the mouth? What features does it have?

6. What are the functions of the mouth?

7. What is the function of the esophagus?

8. Discuss the mechanics of swallowing. Which structures are involved?

9. What is peristalsis? How does it work? Where does it occur?

10. What are the main functions of the stomach?

11. What special features does the stomach have that help it perform these functions?

12. The stomach has a very acidic pH. How come it doesn’t become damaged? Explain.

63

13. What are sphincters? Know the locations and names of the sphincters of digestive system.

14. Explain why surface area is so important to the efficiency of the digestive system

15. Discuss how the small intestine is specially designed for maximum absorption.

16. Describe the structure and function of the villi – how do nutrients get absorbed?

17. Secretions chart - all info

18. Relate pH values to parts of the digestive system and explain why certain values are necessary at different locations.

19. Imagine you are eating a piece of pizza. Describe the 3 main nutrients (carb, lipid, protein) moving through the digestive system. Discuss mechanical and chemical digestions at each location and what the end result is of each nutrient. Know all enzymes involved for digestion of these nutrients.

20. Discuss how the pancreas and liver helps to control blood sugar. (negative feedback pathway). Compare the hormones glucagon and insulin.

21. What are the functions of the liver?

22. What is the function of the gallbladder?

23. What is the function of the appendix?

24. What are the functions of the large intestine?

25. What is present in the large intestine to help with digestion? What does this create?

25. Describe the main difference between vitamins and minerals. You should be able to distinguish between vitamin and mineral names. Eg. Is Calcium a vitamin or a mineral?

26. Be able to identify a few problems that can arise from being deficient in a vitamin or mineral. (deficiency disease)

27. What causes diarrhea and constipation?

28. Know causes, symptoms and treatment of one digestive system disorder. Not including eating disorders like anorexia or obesity.

29. Explain a few differences between the frog and human digestive system.

30. Be able to label the Digestive System diagram and the Sphincter diagram at the beginning of the unit.

64

https://www.youtube.com/watch?v=XJdQRqyPgLI - BRAIN FREEZE

https://www.youtube.com/watch?v=IOf-z0D1mHk - drug absorption

https://www.youtube.com/watch?v=_MaglPJKSmU eating rocks

65