1. UNIT 3
SYSTEMS AND
DIGESTION

2. Levels of Organization…
K01
Systems
Levels of Organization…

3. K01: Levels of Organization
Muscle Cells
CELLS
Muscle Tissue
TISSUES
Heart
ORGANS
Circulatory System
ORGANS SYSTEMS

4. Cooperation of Systems…
K02
Systems
Cooperation of Systems…

5. K02: Cooperation of Systems
Systems are not isolated but work together to perform the functions of an organism.
Example: Gas Exchange – the RESPIRATORY
system is needed to bring gases in and
out of the body and the CIRCULATORY
system is needed to transport the gases.
Example: Digestion – the DIGESTIVE system breaks
down the food and the CIRCULATORY
system transports the nutrients.

6. Homeostasis and Feedback…
Systems
Homeostasis and Feedback…

7. K03: Homeostasis and Feedback
HOMEOSTASIS – means “steady state”. Our ability to maintain constant conditions in
our body even with fluctuations in environmental conditions.
e.g. We maintain a constant
temperature,
blood glucose level,
internal pH,
level of hydration, etc.
How? We can maintain these conditions through
FEEDBACK MECHANISMS.

8. K03: Homeostasis and Feedback
FEEDBACK LOOPS – fluctuations to our internal
conditions cause a response to return to normal.
Monitor
Nerves
Coordinating Center
Normal Range
Brain
37ºC
Nerves
Monitor
Sweat
Skin
Adjustment
Regulator
Shiver
Muscles

9. K01
Digestion
Digestive Process…

10. K01: Digestion
Our digestive system takes food into the body and breaks it down both physically and chemically to make it ready for transport to all the cells in our body.

11. Mechanical vs. Chemical…
K02
Digestion
Mechanical vs. Chemical…

12. K02: Mechanical vs. Chemical Digestion
MECHANICAL DIGESTION –
Breaking down food into smaller pieces PHYSICALLY. E.g. Chewing, mixing in the stomach, cutting with knife.
CHEMICAL DIGESTION –
CHEMICALLY breaking down and changing food molecules. E.g. Stomach acids, enzymes, cooking food.

13. K03
Digestion
Parts of
the System…

14. K03: Parts of the System K04 GI tract = food touches Salivary Glands
Accessory Organs = secrete into GI tract
Esophagus
Oral Cavity
Pharynx
Cardiac Sphincter
Pyloric Sphincter
Stomach
Liver
Pancreas
Gall Bladder
Small Intestine
Large Intestine
Appendix
Rectum
Anus

15. Anatomy and Physiology…
K05
Digestion
Anatomy and Physiology…

16. K05: Anatomy and Physiology
ORAL CAVITY – the mouth is the first site of mechanical and chemical digestion in the body. The teeth grind and cut the food while the tongue mixes it with saliva and mucus. This forms a BOLUS of food.
SALIVARY GLANDS – secrete saliva into the mouth. Saliva contains mucus and water to moisten the food and has enzymes (amylase) to begin digestion of starches.
ESOPHAGUS – this narrow tube pushes food from the mouth to the stomach with muscular contractions. (K07)

17. K05: Anatomy and Physiology
CARDIAC SPHINCTER – a band of muscle to prevent food leaving the stomach and going up the esophagus. (heart burn)
STOMACH – churns and mixes the food with acids and stomach enzymes. Starts digestion of proteins and there is some absorption here of water and alcohol. (ulcer)
PYLORIC SPHINCTER – a band of muscle to prevent food leaving the stomach before it is ready to go into the small intestine.

18. K05: Anatomy and Physiology
SMALL INTESTINE – this tube is 7 metres long and is where most digestion and absorption takes place
It is made of 3 sections:
Duodenum – 30 cm in length; most digestion occurs here
Jejunum
Ileum

19. K05: Anatomy and Physiology
PANCREAS – this is the most important digestive organ in the body.
produces and secretes enzymes into the small intestine to help digest
fats
carbohydrates
proteins
It also produces bicarbonate ions which neutralize stomach acids in the food as it enters the duodenum of the small intestine

20. K05: Anatomy and Physiology
LIVER –produces bile salts which help to emulsify fats in the small intestine, stores glycogen (glucose) and some vitamins, and detoxifies the body from harmful chemicals such as alcohol. (cirrhosis)
GALL BLADDER – stores bile from the liver to secrete into the small intestine for help in lipid digestion.(gall stones)
APPENDIX – a vestigial organ in the human body – serves no purpose. (appendicitis)

21. K05: Anatomy and Physiology
LARGE INTESTINE – made up of the ascending colon, the transverse colon, the descending colon, and the sigmoid colon.
contains bacteria which produce some vitamins B &K
absorption of water occurs here, and
movement of food waste to be eliminated from the body. (colon cancer and cellulose)
RECTUM – marks the end of the large intestine …storage area for waste about to be eliminated from the body.
ANUS – sphincter allowing release of solid waste.

22. Enzymes and Secretions…
K06
Digestion
Enzymes and Secretions…

23. K06: Enzymes and Secretions
Source
Site of Action
Function
Salivary Amylase
Salivary Glands
Mouth
Breaks down polysaccharides (starch) to glucose and sucrose.
HCl
Pepsinogen
Mucus
Rennin
Stomach
Converts pepsinogen – pepsin. Kills microbes.
Digestion of proteins
Protects stomach
Digestion of milk proteins
Bile
Liver and Gall Bladder
Small Intestine
Emulsifies fats
Large intestine
Helps move food along

24. K06: Enzymes and Secretions
Source
Site of Action
Function
Bicarbonate
Trypsinogen
Lipase
Erepsin
Pancreatic Amylase
Disaccharase
Pancreas
Duodenum of Small Intestine
Neutralizes stomach acid
Converts to trypsin to digest protein
Breaks down fats
Digestion of proteins
Breaks down polysaccharides
Break down disaccharides

25. Movement and Absorption…
K07
Digestion
Movement and Absorption…

26. K07: Movement and Absorption
Food moves through the gastrointestinal tract by a process called PERISTALSIS. Waves of muscular contractions push the bolus of food along from behind.

27. K07: Movement and Absorption
In the small intestine there are many folds called VILLI which increase the surface area to allow for more absorption of nutrients from the intestine to the bloodstream. This absorption occurs usually by simple diffusion but active transport may be used for some substances.

28. K08
Digestion
Control of Digestion…

29. K08: Control of Digestion
Russian physiologist, Ivan Pavlov, is famous for his experiments on dogs. He performed a number of experiments which showed that digestion is under both nervous and hormonal control.
2) HORMONAL – Pavlov then connected the circulatory systems of two dogs. Food placed in the mouth of one dog caused gastric secretions in BOTH dogs – a hormone called GASTRIN was carrying a message to the stomach. Enterogastrone is also released when fats are eaten.
1) NERVOUS – Pavlov noticed that when food was placed in a dog’s mouth and not allowed to travel to the stomach, the stomach still produced gastric secretions. When he cut the vagus nerve, gastric secretions were reduced.

30. Nutrition and Malnutrition…
K09
Digestion
Nutrition and Malnutrition…

31. K09: Nutrition and Malnutrition
NUTRITION means a person is receiving all the nutrients they need from all the different nutrient groups.
MALNUTRITION means a person is deficient in one or more of the nutrient groups. This can lead to various medical conditions and diseases.

32. K10
Digestion
Nutrient Groups…

33. K10: The 6 Basic Nutrients
1) CARBOHYDRATES – used for energy in our bodies
2) LIPIDS – used for storage of energy, cell structure
3) PROTEINS – used for cell structure and as enzymes.
Ten of the twenty amino acids can be made by our
body. The other ten must be eaten in the diet and
are called the ESSENTIAL amino acids. Meats
contain all the essential amino acids so are
COMPLETE proteins. Vegetables may be lacking
in certain amino acids.

34. K10: The 6 Basic Nutrients
4) MINERALS – needed for body structure (bones), fluid balance, muscle contraction, nerve impulse, and blood clotting
5) VITAMINS – used as components of cell metabolism
6) WATER – needed for many things – temperature regulation, chemical reactions, solvent, transport, makes up most volume of cells, etc.
FIBRE – Sometimes included as a nutrient as it is essential in the diet. It helps us to retain moisture long enough to absorb from the large intestine and also signals the colon to move food along to be expelled from the body.

35. SOB
Food Burning Lab

36. Fats yield 9. 3 Kcal/gm, while carbohydrates yield 3. 79 Kcal/gm
Fats yield 9.3 Kcal/gm, while carbohydrates yield 3.79 Kcal/gm. Fats store six times as much energy as glycogen.

37. Apple down GI tract:
Why do I have Gas?
Theme page:
Virtual Tour and Explanation:
Virtual Anatomy: