Human Nutrition

Essential Questions

•What life process?

•How do human carry out this life process?

•What happens to the foods we eat?

•How do nutrients get into our blood stream?

What is nutrition???

•Organisms obtain preformed organic compounds from environment (ingestion, digestion, and egestion)• “You are what you eat!”• Your body grows rapidly, the food

you eat provides the material your body needs to build cells, tissues, and organs….

7 Groups of Nutrients

1. Carbohydrates energy sources; can be broken down to enter the cell

2. Lipids produce ATP, must be broken down to enter cell

3. Proteins- must be broken down to enter cells (growth & repair)

4. Vitamins small enough to be absorbed by cells without being broken down

5. Minerals

6. Water

7. Roughage-materials body cannot digest; mostly complex carbs (cellulose, fiber, fruits & veggies); serves to push food through large intestine (egestion)

2 Types of Digestion1. Mechanical-

No chemical changes occur

Increase surface area exposed for chemical digestion

Occurs in mouth and stomach

food is broken into smaller pieces by cutting, grinding, or tearing

Chemical- “hydrolysis”Large molecules are changed chemically to

smaller molecules Complex carbs (disaccharides/polysaccharides) broken

down to Lipids broken down to Protein broken down to

simple sugars (monosaccharides)

3 fatty acids & 1 glycerol

amino acids

Human Digestive System

Continuous 1 way tract with accessory organs

Food moves through the system by peristalsis (wave-like muscular contractions)- Peristalsis Video

A trip through your digestive tract takes about 18-20 hours.

Parts of the Digestive System1. Oral Cavity (mouth) (digestion begins approx 1 min)

Ingestion occurs Contains teeth and tongue for mechanical digestion Salivary glands produce saliva which contains amylase that

digests starch during chemical digestion2. Pharynx (throat)

Passageway from mouth to esophagus

Parts of the Digestive System3. Esophagus (1 min)• Food tube; connects throat to stomach• No digestion here• Swallowing initiates peristalsis • Epiglottis- flap over trachea (wind pipe) which closes

when you swallow, prevents choking, inhalation of food/fluids

4. Cardiac Sphincter-• muscle that controls the opening from esophagus to stomach

(“heartburn”)

Parts of the Digestive System

5. Stomach- thick walled muscular organ Mechanical digestion occurs when the stomach

grinds food.

Chemical digestion occurs here: Lining secretes HCl and pepsin Proteins begin digestion here (protease) Pyloric glands secrete mucus so stomach doesn’t digest

itself! Chyme- the soupy liquid formed from digestion of solids

Chemical Digestion in the StomachUlcer-

•Digestion in the stomach occurs for 2-6 hours for solid foods.

when the mucus layer breaks down, causing sores caused by bacteria (Helicobacter pylori), stress, diet; may bleed

6. Pyloric Sphincter- muscle that controls the opening from stomach to intestines

Parts of the Digestive System

7. Small Intestine- “small” refers to diameter, not length • 6.5m long, 2.5cm in diameter

• Partially digested food from stomach goes to the small intestine

• Most digestion occurs here (not stomach)

• All digestion is completed here

Small Intestine

• Absorption of nutrients occurs in the small intestine!!!• Lined with villi (fingerlike projections

that increase surface area for absorption)• Capillaries absorb glucose, amino

acids• Lacteals absorb: lipid end products

(fatty acid, glycerol)- part of lymphatic system

Anatomy of the Small Intestine

8. Pancreas

produces and secretes pancreatic juices Into the small intestine.

• Aids in chemical digestion

•Uses several enzymes:amylase, protease, lipase

9. Gall Bladder• Stores Bile made by the liver• Aids in chemical digestion• Bile aids in preparing fats for digestion.

10. Liver Liver produces bile – emulsifies fats (stored in the gall

bladder

Aids in mechanical and chemical digestion

Liver is the body’s largest internal organ

Digestive Enzymes • Intestinal Enzymes-• Pancreatic Enzymes- (dumped into small intestine)

• Liver produces bile (stored in the gall bladder) which emulsifies fats• Fat globules are broken down to smaller fat globules

through mechanical digestion to increase surface area for chemical digestion

• Gall stones:

maltase, protease, lipaseamylase, protease, lipase

hard cholesterol deposits accumulated in gall bladder

You are what you eat!!!• Fate of Fat

• Once absorbed by the small intestine, the body can use these nutrients for:• Energy• Synthesis• Assimilation• It takes approximately 12 hours for food to

travel through the small intestine!

Large Intestine

11. Large Intestine (colon) 1.5m long, 6cm diameter Water absorbed from waste too much absorbed= too little absorbed= Undigested food forced out through anus by peristalsis, these

wastes are called

It takes 3-4 hours for food to pass through the large intestine. FYI: The appendix= small pouch where large and small intestine

join- has NO FUNCTION!

constipation diarrhea

feces

Summary of Digestion….

Nutrient Digestions Begins Digestion Ends

Carbohydrates

Protein

Lipids

Mouth

stomach

small intestine small intestine

small intestine

small intestine

Inside Eddie Johnson

Disruption of HomeostasisTopic: Heterotrophic NutritionMode of Disruption Malfunction Description

Inheritance Lactose intolerance Inability to digest diary products (lactose) b/c you lack the enzyme lactase; results in intestinal distress

Toxic Substances Food poisoning: caused by bacteria such as E. coli & salmonella

Toxins released by bacteria cause intestinal distress & kidney disease

Poor Nutrition Deficiency diseases: scurvy, rickets, & goiter

Lack of a vitamin or mineral in diet. Results in poor general health- need to supplement diet.

Disruption of HomeostasisTopic: Heterotrophic NutritionMode of Disruption Malfunction Description

Organ Function Gall StonesConstipation/ Diarrhea

-Accumulation of hardened cholesterol, results in disruption of bile secretion-Too little or too much water in diet

Personal Behavior Eating Disorders:-anorexia-bulimia

- Robs your body of essential nutrients, leads to poor general health, ulcers, and death

Infectious Disease Tapeworm (contracted when we ingest larva in uncooked or undercooked meat- if the animal had tapeworm)

-Worm grows in intestinal tract -Robs your body of nutrients-Leads to deficiency diseases