Nutrition and Digestion

1
Nutrition and Digestion

• Chapter 38

2
Nutrition-

• The process by which organisms get food and break
  it down for metabolism

3
6 Essential Nutrients

• Proteins (organic)
• Carbohydrates (organic)
• Fats (organic)
• Vitamins (organic)
• Minerals (inorganic)
• Water (inorganic)

4
Remember

• Autotrophs-
• organisms capable of making their own food

• Heterotrophs-
• organisms that must obtain food from their
  environment

5
The Human Digestive System

• Also called the alimentary canal or the
  gastrointestinal tract

6
Diagram of Human Digestive System
1.
2.
4.
3.
5.
6.
7.
8.
9.
10.
11.
7
Digestive system organs

• The alimentary canal (digestive tract) of the
  human is made up of the following ordered
  sequence. Food passes through these structures
• -oral cavity or mouth
• -pharynx
• -esophagus
• -stomach
• -small intestine
• -large intestine

8
Accessory organs

• Other organs/glands are important for disgestion.
  Food does not pass through these structures
• -gall bladder
• -liver
• -pancreas
• -appendix

9
Functions of all organs and structures in the
human digestive system
10
I. Oral cavity or mouth
2.

• Lining of the mouth is epithelial tissue
• Secretes mucous (protection)
• Stimulation of taste buds results in secretion of
  saliva
• This starts chemical digestion
• Carbohydrate digestion begins in the mouth
  (amylase)
• Teeth begun mechanical digestion

1.
3.
4.

1. Salty
2. Sweet
3. Sour
4. Bitter

11
II. Pharynx

• Food passes through this narrow region and goes
  into the esophagus.

12
III. Esophagus

• Tube that connects the pharynx to stomach.
• Food enters by wavelike motion of smooth muscle
  contractions called peristalsis.

13
IV. Stomach

• sac like
• contains gastric juice
• This is water, hydrochloric acid, mucus, and the
  enzyme pepsin.
• Protein digestion begins here.
• Bacteria are destroyed by acid environment
• Peristalsis is occurring here.
• Ulcers may develop here.

14
V. Small intestine

• About 20-25 feet long
• Contains folds or villi that increase the surface
  area

Villi___________
15
Small intestine cont

• Most absorption of nutrients into the blood
  stream occurs here.
• Most chemical digestion is occurring here.
• Lipid digestion occurs here.
• Peristalsis is continuing.
• The small intestine receives secretions from the
  liver and pancreas.

16
VI. Large intestine (colon)

• Water absorption
• Feces formation
• Appendix located at end of large intestine
• This is a vestigial organ-it no longer has a
  useful function.

17
VII. Liver

• Largest organ
• Functions
• Secretes bile
• Produces urea
• Breakdown of worn out red blood cells
• Breakdown of proteins into amino acids
• Removes sugar from blood
• Stores sugar as glycogen

18
Liver cont

• Excessive use of alcohol and some drugs can cause
  damage to the liver
• Bile produced by liver is stored in gallbladder.
• Function is to break up lipids
• Therefore people without a gallbladder must watch
  their fat intake.

19
VIII. Pancreas

• Functions
• Hormone secretion. (hormone-chemical in blood
  for regulation)
• Secretes enzymes into small intestine for
  digestion.
• Regulates blood sugar levels.
• Cells inside pancreas called the Islets of
  Langerhans
• Secretes glucagon when blood sugar is too low
• Secretes insulin when blood sugar levels are too
  high

20
(No Transcript)
21
Malfunctions of the Digestive Tract

• Ulcers-erosion of the lining in the stomach
• Constipation-large intestine emptied with
  difficulty. Caused by too much water absorption
  in large intestine
• Diarrhea-disturbance characterized by decreased
  water absorption and watery feces. May result in
  severe dehydration.
• Appendicitis-inflammation of appendix
• Gall stones-accumulation of cholesterol in gall
  bladder