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Travel Brochure of the Digestive System

Duodenum Dynamics Ad Agency

Manager: Vella Liu 11B

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A luxury tour• The Digestive System!!! The most fabulous

tourist destination ever! You just need to take nearly a week, enjoy the beautiful scenes (Biology is beautiful!) and get better understanding of your body.

• You will become a bolus and travel along the path of the Digestive system

• Fee: for adult $200/person for children $100/person insurance $20/person

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Our destinations• Compare mechanical digestion to chemical digestion

P4--5• List the parts of the digestive system and give their

functions, potential risks& Describe the structure of the villi and explain how its function is related to its structure P7--30

• Discuss the importance of the liver and pancreas in digestion. List the substances they produce and explain their function. P32--37

• Explain the results of the chemical digestion of carbohydrates, proteins and fats and discuss if this digestion occurs in the mouth stomach and/or small intestines & Explain the function of the digestive enzymes (amylase, protease and lipase) P39--43

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mechanical digestion v.s chemical digestion

• Mechanical digestion

• What? Physically breaks down the food

• Where and How?

1.In oral Cavity, the teeth chew the food

2. In the stomach, it’s the churning and mixing food

Mechanical digestion works similar to the electronic blender

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• Chemical digestion

• What? Breaking down food macromolecules to smaller molecules by enzymes (different enzymes have different functions)

• Why? Food can be absorbed more easily.

• Where? Oral cavity, stomach, intestines.

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Let’s start our alimentary canal tour!

• Each part of the digestive system is a tourist attraction

• Each digestive system malfunction or disease will receive a caution. (That’s what your insurance for)

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Oral Cavity• What? A fancy way to say “mouth”• Function: receive & store food while the teeth

are chewing it. (without this closed area, the food will never ever get into your stomach)

• Made up of: Lips: hold the food (like the guard of oral

cavity)Teeth: physically break down food into bolusTongue: directs food towards teeth, and then

directs bolus towards the pharynx

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Important features: Salivary glandsFunction: produce salivaSaliva’s function:1.makes food wet (become

slippery and be easily swallowed)2.Contains enzymes break down starch

into carbohydrates (the last part of ppt will describe enzymes in details)

3.locations of salivary glands: Sublingual gland (beneath the tongue), Submandibular gland (beneath the floor of the mouth), Parotoid gland (right in front of ears, on the cheek )

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2.Pharynx

2.1 Where?

1.Back of the throat

2.Includes oral and nasal cavities & where they join

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2.2 Important features

• Epiglottis

1.Covers the glottis

2.The entrance of trachea

3. Close when swallowing happens

Why? Preventing the bolus goes to wrong way

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2.3 extra information: swallowing

• Process:

Reflex action:1.bolus moves down to the throat

2.soft palate closes the nasopharynx, epiglottis closes the trachea

3. bolus moves down to the esophagus, peristalsis (explained later) happens

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3.The Esophagus3.1 What? Muscular tube, joins the pharynx

and the stomach, expands only when bolus comes down

3.2 Function: passageway, pushes bolus downwards to the stomach through peristalsis

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3.3 Important process: peristalsis

• What? Rhythmic contraction squeezes bolus downwards

• Location: the esophagus, continues in all the organs of the digestive pathway (i.e. the intestine tract)

• Explanation: the area above the bolus squeezes; however, the bolus and the area below the bolus are relaxed. As a result, it’s easy to push bolus downwards

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4. The stomach4.1 Structure: J-shaped, thick wall with folds

(rugae), mucous on the inside surface4.2 Location: left side of the body, below the liver,

above the pancreas4.3 Function: 1.stores food2. Churns food, helps digesting food physically

product: acid chyme3. Begins digestion of protein4. Moves food to the small intestine

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4.4 sphincters

• Cardiac Sphincter• Band of muscle• At the top of the

stomach• Function: 1.prevent

stomach acid from entering the esophagus

2.Opens when bolus enter to the stomach

• Pyloric Sphincter• Band of muscle• At the bottom of the

stomach• Function:1.acid

chyme can’t easily escape

2. Allows small amounts of chyme entering the duodenum

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4.5 Caution (additional info)

4.51 Heartburn

Gastric juice escapes the guarding (cardiac sphincter) enters the esophagus The pain often rises in the chest, may radiates to the neck, throat, or angle of the jaw.

Internal fire, rising from the stomach

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• 4.52 gastric perforation

What? The mucous (internal layer) of the stomach The penetration of the wall of the stomach exists a hole stomach contents escape into the abdominal cavity

Harm: potential bacterial infection to the abdominal cavity & entire body

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4.6 gastric juice4.61 stomach acidMainly: HCl acidic pHFunction: 1.prodives the optimum pH for

pepsinogen to work2. Kill bacteria inside the food

4.62 pepsinogenImportance: changes into pepsin (enzyme) when

exposed to HClPepsin function: break down protein into peptides

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5. Duodenum• First 25cm of the small intestine

• Contain ducts connected with the gall bladder and the pancreas

• Bile and pancreatic juice come and join here (details explained later)

Duodenum and internal surface

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6. The Small Intestine

6.1 Diameter: small 2.5cm Distance: long 7m6.2 Function: 1. further digestion 2. Absorption of nutrients6.3 Important feature:Villi, microvilli, lactealsVilli: projection, finger like, epithelial cells on the

outsideMicrovilli: on the epithelial cells, similar structure

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• Function of villi and microvilli: the shape of them increase surface area more site for absorption

Lacteal: blood capillaries (even microvilli have these) + lymphatic capilary

How it function: absorbs the nutrients (i.e. fatty acids and amino acids), and they will travel through the veins, be used by the cells of the entire body

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7.Appendix

7.1 Location: at the junction of the small intestine and colon (connect them)

7.2 Function: no functions in human bodies

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7.3 appendicitis(extra info)

• Inflammation of the appendix

• How it forms: the food goes into the wrong way, it accumulates inside the appendix, the appendix may burst, and the result may cause death

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8. The large intestine (colon)

8.1 consists of : cecum (the first length of it), ascending colon, transverse colon, descending colon, sigmoid colon

8.2 Diameter: larger 6.5cm Distance: shorter 1.5m8.3 Escherichia coli: the colon is there homeBreak down some indigestible material, produce

some vitamins and molecules, beneficial to humans

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8.4 Function:1. absorbs water, salts, vitamins

2. Forms the indigestible wastes as feces

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9. Pelvic Cavity

9.1 Rectum

Structure: pouch like, enlarged portion

Function: stores undigested food (feces) for a short period of time

rectum

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• 9.2 Anus

1.A sphincter = a band of muscle

2. Allow undigested wastes (feces) to exit the body

3. Why this is important? Without it, we can’t control the feces getting out of our bodies, so it will cause gatism

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4.By the way------

The important process:

Elimination / defacation

Discharge of feces from the rectum through the anus

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Let’s zoom in the liver and the pancreas!

special top 2 tourist attractions

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10. The Liver

10.1 Function: 1. produce bile

2. Destroys old red blood cells, converts hemoglobin to the bile

3. After eating: stores glucose as glycogen

Between eating: breaks down glycogen into glucose

4. deamination: breaks down amino acids & produces urea

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5. (also) produces blood proteins from amino acids

6. Detoxifies and metabolizes poisonous substances

10.2 Importances:

1.Maintain the blood glucose level

2. bile: emulsifies fats= breaks fats down into fat droplets easier for body to absorb fat molecules

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11. The Gall Bladder

• Function: stores the bile

• Process: 1.acid chyme stimulates the duodenal wall

2.release cck

3.stimulates the release of bile

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12. The Pancreas

12.1 Both an Exocrine and an Endocrine organ

12.2 Exocrine: enzymes1. Pancreatic amylase: breaks downstarch

into maltose2. Trysin (protease): breaks down protein

into peptides3. Lipase: breaks down fat droplets into

glycerol and fatty acids

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12.3 Endocrine (produces hormones)

• Insulin• Function: lower the

blood concentration• Makes liver and

muscles store spare glucose

• Helps synthesis of protein, fats

• glucagon• Function: increases

the blood concentration

• Makes liver and muscles break down glycogen

• Stops synthesis of protein, fats

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12.4 sodium bicarbonate

•  NaHCO₃ (basic)

• Function: be secreted by the pancreas in order to neutralize the acid in the acid chyme (get a neutral pH, the duodenum doesn’t have the mucous like the one the stomach has)

The results of the chemical digestion of organic molecules

& Let’s get to know some friends!!

(function of the enzymes)

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13.carbohydrates• Process: hydrolysis

13.1 Enzyme: Salivary amylase

Location: mouth

Produced by: salivary glands

Function: starch + H2O maltose

13.2 enzyme: Pancreatic amylase

Location: small intestine (the duodenum)

Produced by: the pancreas

Function: starch + H2O maltose

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13.3 Enzyme: maltase

Location: small intestine

Produced by: small intestine

Function: Maltose + H2O Glucose + Glucose

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14. Proteins14.1 Enzyme: Pepsin (protease)Produced by: gastric glandsLocation: the stomach

Function: Protein + H2O Peptides 14.2 Enzyme: Trypsin (protease)Produced by: the pancreasLocation: the duodenum (small intestine)

Function: Protein + H2O Peptides

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14.3 Enzyme: Peptidases

Produced by: small intestine

Location: small intestine

Function: Peptides + H2O Amino Acids

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15. fats15.1 bile (not an enzyme)Produced by: the liverLocation: the duodenumFunction: break down fats into droplets physically

15.2 Enzyme: lipaseLocation: the duodenum (small intestine)Produced by: pancreas

Function: Fats + H2O Glycerol + 3 fatty acids

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Reference

• A lot of thanks to Mr. H’s notes!

• A lot of thanks to Biology 12 textbook

• Extra information (digestive problems and diseases)

• http://en.wikipedia.org/wiki/Heartburn

• http://en.wikipedia.org/wiki/Gastric_perforation

• http://en.wikipedia.org/wiki/Appendicitis