1. HUMAN ANATOMY & PHYSIOLOGY

2. Human Digestive System Animation: Organs of Digestion

3. Warm-Up - journal
Write down in correct sequence all the organs (at least 5) through which their food passes as it travels along the digestive tract.
Then try to list any glands or organs that are found along the digestive tract, but through which food does not pass.

5. Following the Digestive Trail
Accessory Organs
Tongue
Epiglottis
Pharynx (throat)
Salivary glands
Mouth
Esophagus
Stomach
Small Intestine
Large Intestine
Accessory Organs
Pancreas
Liver
Gall Bladder

6. The Need for Digestion Major Functions: 1. Ingestion - taking in food
2. Digestion-ability to process food in the body into a form that can be absorbed and used or excreted.
3. Absorption -pulling nutrients out of the food, occurs in the small intestine
4. Egestion-removal of undigested food

7. Overview: Food processing occurs in four stages
Small molecules
Pieces of food
Nutrient molecules enter body
cells
Chemical breakdown (enzymatic hydrolysis)
Mechanical breakdown
Undigested material
Food 1
INGESTION 2
DIGESTION 3
ABSORPTION 4
ELIMINATION
Figure 21.2

8. A. Purpose B. Why? food O2 mitochondria Provides energy to stay alive
Process of breaking food particles down into molecules small enough to be absorbed by cells
To help build cells, tissues and organs
ATP energy for synthesis
food
ATP
B. Why? O2
mitochondria

9. C. Types of digestion MECHANICAL
Changes the physical form of food (physical changes)
Mouth- teeth chew (masticate) & crush food
stomach muscles (rugae) grinds & churns
2. CHEMICAL
Changes the chemical composition of food into a new substance with the aid of digestive enzymes ( chemical changes).

10. Review: Nutrition Carbohydrates Broken down into monosaccharides
Food broken down to usable nutrients and absorbed into the bloodstream.
They are used by the body for metabolism, building and repair
Nutrients include carbohydrates, proteins, lipids, vitamins, minerals and water.
Carbohydrates
Broken down into monosaccharides
Body’s main source of energy.
Proteins
Broken down to amino acids
Supply the raw materials for growth and repair.
Lipids
Broken down to 3 fatty acids and glycerol
They are used to make steroid hormones, cell membranes
Store energy

11. End product (building blocks)
Nutrient
End product (building blocks)
Transport
Carbohydrate
Simple sugars
(glucose & fructose)
Diffusion (w/out energy & high to low)
Proteins
Amino Acids
Diffusion
Lipids (Fats)
3 Fatty Acids
1 glycerol
Diffusion &
Active transport (with energy, low to high)
Draw/label
this
IN: Nutrients & O2
To the cells
Artery
OUT: CO2

12. D. Gastro Intestinal Tract
How is the digestive system similar to a vacuole in a one celled organism?
One celled organism (ameoba, parameciu, euglena)- it is intracellular (vacuoles release digestive enzymes)
Humans- it is Extracellular (outside the cells then absorbed into the bloodstream)
Reference: RB: pg 13 table 1-1

13. Review: Which type of digestion (mechanical or chemical)?
Chewing a saltine?
Saliva breaking the saltine down into molecules of glucose?
Your tongue breaking pieces of a hamburger apart?
Pepsin (an enzyme) in your stomach breaking the hamburger into amino acids?

14. Digestion System video clip –click on imageDigestion biology Animation

15. Your Turn…learn the functions of the organs
Group Activity - match function card with the organs in your activity packet
As a Pair - Go to: My computer Assignments (drive R:) KE Connelly Living Environment Digestion ppt
Return to seats and check your cards – rearrange if necessary to make it correct
Write the functions in your chart

16. Following the Digestive Trail – a one way tube
Accessory Organs
Tongue
Epiglottis
Pharynx (throat)
Salivary glands
Mouth
Esophagus
Stomach
Small Intestine
Large Intestine
Accessory Organs
Pancreas
Liver
Gall Bladder

17. Following the Trail 1 Mouth
Mechanical digestion begins here - chewing/crushing food
Salivary glands secrete saliva, which moistens and lubricates food for swallowing.
Saliva contains amylases (enzymes), which start the chemical breakdown of carbohydrates (starch).
All that in spit!

18. Following the Trail 2 Esophagus Muscular tube (aka: food tube)
As we swallow, we push food along the tube until the food reaches our stomach. This process of pushing down the food uses muscular wave-like contractions is called peristalsis
Peristaltic contractions transport food to the stomach and allow a person to swallow even if he/she are upside down.
Peristalsis biology Animation
Click Here for animation

19. Following the Trail 3 Stomach
Food (bolus) mixes with acidic gastric juices (HCl) and an enzyme called pepsin to form chyme.
The chemical digestion of proteins begins in the stomach.
Mechanical digestion continues-stomach grinds & churns the bolus
Still, the epithelium is continually eroded, and the epithelium is completely replaced by mitosis every three days.
Gastric ulcers, lesions in the stomach lining, are caused by the acid-tolerant bacterium Heliobacter pylori.
Ulcers are often treated with antibiotics.
Pepsin is secreted in an inactive form, called pepsinogen by specialized chief cells in gastric pits.
Parietal cells, also in the pits, secrete hydrochloric acid which converts pepsinogen to the active pepsin only when both reach the lumen of the stomach, minimizing self-digestion.
Also, in a positive-feedback system, activated pepsin can activate more pepsinogen molecules.
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach lining

20. FYI- the small intestine has 3 parts:
Following the Trail 4
FYI- the small intestine has 3 parts:
Small intestine
Secretes digestive enzymes to begin breaking down fats
Continues and completes ALL chemical digestion of carbs, proteins and fats
Absorbs nutrients into the blood stream
S.I. lined with fingerlike projections, called villi, which, in turn, are covered by microvilli which increase surface area
The villi contain capillaries and lymphatic vessels for the absorption of nutrients
Nutrients move into blood stream by what process (Think H to L!)? DIFFUSION!!!!!!!!!
About every 20 seconds, the stomach contents are mixed by the churning action of smooth muscles.
As a result of mixing and enzyme action, what begins in the stomach as a recently swallowed meal becomes a nutrient-rich broth known as acid chyme.
At the opening from the stomach to the small intestine is the pyloric sphincter, which helps regulate the passage of chyme into the intestine.
A squirt at a time, it takes about 2 to 6 hours after a meal for the stomach to empty.

21. Cross-Section of small intestine
A Closer look at the villi & microvilli of the small instestine
Absorption through increases surface area for absorption
Cross-Section of small intestine
Villi
Microvilli
SMALL INTESTINES 6 meters long, but can stretch to cover a tennis court

22. Following the Trail 4 cont….the accessory (helper) organs
Food DOES NOT pass through these organs
These organs secrete substances to aid in digestion

23. Pancreas Found under the stomach
Following the Trail 4 cont….
Pancreas Found under the stomach
Secretes enzymes (lipase, amylase, protease) into the small intestine
Secretes a base into S.I. to neutralize stomach acid WHY??
So digestive enzymes aren’t denatured and can work!
Makes hormones insulin & glucagon to balance blood sugar levels to maintain homeostasis
pancreas
small intestine

24. Balancing Blood Sugar levels
Homeostasis
Balancing Blood Sugar levels
insulin
body cells take up sugar from blood
liver stores sugar
reduces appetite
pancreas
liver
high
blood sugar level
low
liver releases sugar
triggers hunger
pancreas
liver
Feedback
glucagon

25. Following the Trail 4 cont….
Liver
Produces & secretes bile to emulsify (breaks up) fats
stores bile & releases to the small intestine
Gall Bladder
FYI - bile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brown

26. Large intestines (colon)
Following the Trail 5
Large intestines (colon)
NO digestion occurs here
WATER and vitamin K gets reabsorbed from undigested chyme
Lined with bacteria (E. coli)
Holds undigested or unabsorbed food wastes (feces)
mainly cellulose from plants called roughage or fiber- keeps everything moving & cleans out intestines
Masses of bacteria
Final stop for undigested material…eliminate feces
Rectum
So don’t forget to wash your hands!
Anus

27. E. Digestive Homeostasis Disorders
Body Invaders: Digestive Problems : Video : Discovery Health
1. Stomach
1) Mucus that prevents stomach from digesting itself
a) Peptic ulcer occurs when layer of mucus fails (open sores)
b) Gastric juices reach wall of stomach and begin to break down (painful)
Ulcers biology Animation
2) Treatment
Before: Antacid would reduce amount of acid in stomach but would return
Recently: Ulcer is an infection by acid resistant bacteria Helicobacter pylori
Treatment – antibiotics

28. 2. Appendix
No function – may have once been used to digest plants (vestigal organ)
Appendicitis – inflammation of the appendix – caused by E. Coli bacteria

29. 3. Large Intestine
Constipation- too much water reabsorbed from the feces
Diarrhea-too little water reabsorbed from the of feces; prolonged diarrhea can cause dehydration of body tissues.

30. 4. Colon Cancer
One of the most common types of cancers in North America
Colon – section before the rectum on lg. Intestine
Cause:
Diet low in fiber causes feces to move too slow through colon
Hereditary predisposition

31. 5. Gallstones
small hard stones made of cholesterol that collect in the gallbladder.
Due to a high saturated fat diet
hereditary
Heart Burn Heartburn biology Animation

32. Digestive System Fill-In

33. Digestive System Fill-In Answers