BIO1100 Dr. Morris Troy University Exam 3 - Module 4, Human Biology

Digestive system purpose

Sustaining the body

4 stages of food processing:

1. Ingestion (/eating)

2. Digestion (/breaking down)

3. Absorption (of nutrients)

4. Elimination (of anything that cam’t be processed)

Peristalsis (what & where)

= wave-like contractions of smooth muscle, spands from esophugas to intestines

2 types of smooth muscle fibers (& what they do):

• Vertical— temporarily shorten distance btwn. food and next organ

• Horizontal— squeeze behind food

Organs of the Digestive System:

1. Oral Cavity

2. Pharynx

3. Esophogas (+ Epiglottis)

4. Stomach

5. Small Intestine

6. Large Intestine

7. Rectum

8. Anus

Oral Cavity (where, kinds of breakdown, what begins digestion here)

• = the mouth

• Physical breakdown: tongue manipulates food & teeth initiate mechanical breakdown → bolus

• Chemical breakdown: salivary glands create saliva that initiates chemical breakdown of carbs

• Carb digestion starts here

Bolus

= undigested food

)Pharynx (where, shared?)

• = (opening to) throat

• Shared organ btwn digestive & respiratory system

Esophogas (what)

= food pipe; connects Pharynx to Stomach

Epiglottis (what it does, what it’s made of)

= flap of cartilage (connective tissue) that controls what goes doen Trachea vs Esophogas

Stomach (what it is, what it’s made of, what starts digestion here)

• = muscular bag

• 3 kinds of tissue;

• Protein digestion starts here

  • Pineapple & papaya are natural protein digestors

3 kinds of tissue in Stomach:

1. Muscular

2. Connective

3. Epithelial

What does muscular tissue do in the Stomach?

churns food

What does connective tissue do in the Stomach?

holds organ in place

What does epithelial tissue do in the Stomach?

• highly folded to increase surface area

• 3 purposes;

Rugae

Highly folded folds of epithelial tissue

3 purposes of epithelial tissue in the Stomach:

1. Secretes HCl acid (3 purposes)

2. Secretes enzymes for protein breakdown

3. Secretes mucus to protect stomach from being digested

3 things HCl acid does:

• Chemical digestion

• Kills germs that don’t get killed by bacteria

• Protein digestion

Stomach Acid

• Duct connects stomach to small intestine, valve controls how much drips into s.i. (drop by drop, or else small intestine would get burned up)

• Either Pepsinogen or Pepsin

Pepsinogen

Inactive; there when NOT eating food

Pepsin

Active; there when eating food, absent when NOT (otherwise stomach would digest itself)

Small intestine (measurements, what it does, what starts digestion here)

• 18ft long, ½ diameter of large intestine, SA size of baseball diamond

• Nutrient absorption, chemical digestion

• Lipid digestion starts here

Villi & Microvilli in Small Intestine

• Villi = finger-like projections

• Microvilli = hair-like projections; increases SA the most, infections/viruses (ex. stomach bug) can break these off and must be regrown

Large Intestine (aka, measurements, what it does)

• aka the Colon

• 5ft long, 2x diameter of small intestine, SA much smaller

• Water & water-soluble vitamin reabsorption

• Helps eliminate undigested food

• Synthesizes Vitamin K (essential for proper blood clotting)

• Connected to Appendix

Appendix

• houses white blood cells → help immune system concerning food germs

• Prone to infection as w.b.c. fight germs

• **Appendicitis

• CAN be lived without

Rectum

= temporary storage of feces

Feces (what, made up of)

= “solid waste”; made up of mostly water, fiber, & dead bacteria

Anus

= where waste leaves body

Accessory Glands

1. Salivary Glands

2. Liver

3. Gallbladder

4. Pancreas

Salivary Glands (what they do)

Secrete saliva

4 roles of Saliva:

1. Lubricates (abrasive foods; ex. almonds, popcorn, etc.)

2. Neutralizes (acidic foods; ex. orange juice) to protect teeth

3. Kills germs

4. Enzymes to start carb digestion

Liver (size vs. rest of glands, connected to what)

• Biggest gland in body

• Connected to gallbladder by duct

• Multiple roles;

Roles of Gallbladder:

• Remove toxins

• Regenerates blood cells

• Secretes bile;

Role of bile

Performs process of emulsification

Emulsification

= increasing SA of fats to make easier dissolvably by enzymes (lipases)

Lipases

= enzymes that break down lipids

Gallbladder (stores what, makes anything?, helps digest what, can be lived without?)

• Stores excess bile that liver makes

• Doesn’t make anything itself

• Helps lipid digestion

• CAN be lived without

Pancreas (where, connected to what)

• Critical but small organ located just below stomach

• Connected to small intestine by duct

• 3 major roles in digestion;

3 major roles of Pancreas in digestion:

1. Makes insulin for healthy blood sugar levels in circulatory system — also important to nervous system (high blood sugar / diabetes correlated w/dementia)

2. Secretes alkaline (high pH) fluid to neutralize stomach acid (low pH) — keeps small intestine from being burned up by HCl

3. Secretes enzymes that break down ALL nutrient types )carbs, lipids, & proteins)

Medical conditions associated w/the digestive system:

• Acid Reflux

• Gastric Ulcer

• Colon Cancer

• Pancreatic Cancer

• Appendicitis

Acid Reflux (what it is, caused by what, treatments, can turn into what)

• = backflow of stomach acid into lower part of esophagus

• Happens when stomach valve doesn’t close all the way

• Treatments: antacids like Tums, Pepto

• If not treated, can lead to Esophageal Cancer

Gastric Ulcer (what it is, caused by what, what happens in body, treatments)

• = ulcer in stomach

• Caused by bacteria that can survive in harsh environment of stomach — “Helicobacter pylori”

• Shuts mucus away, makes wall prone to being digesting

• Treatment: powerful antibiotics

)Colon Cancer (what it is, ways to reduce risk)

• = cancer in colon / small intestine

• Reduce risk by exercising eating less saturated fats, and eating more fiber

Pancreatic Cancer (what it is, why it’s dangerous)

• = cancer in pancreas

• very dangerous because pancreas completes so many function

Appendicitis (what it is, treatment)

• = appendix becomes infected

• Often removed

3 functions of Nutrients:

• Sources of energy

• Building up own tissues & biochemistry

• Regulators — controlling body processes, making sure they happen smoothly & efficiently

6 classes of nutrients:

1. Carbohydrates

2. Lipids

3. Proteins

4. Vitamins

5. Minerals

6. Water

Carbohydrates (main function, digested where to where)

• Quick energy

• Digested oral cavity → small intestine

Lipids (main function, digested where to where)

• Stored energy

• Digested small intestine → small intestine

Proteins (main function, digested where to where)

• Building up own tissues & biochemistry

• Digested stomach → small intestine

Vitamins (funct., calories?, size vs. minerals, organic?)

• Regulators; assist enzymes in speeding up chemical reactions

• No calories

• Larger than minerals

• Organic (have Carbon)

2 Vitamins:

1. Water-soluble

2. Fat-soluble

Water soluble (ingestion, 2 kinds)

• must be ingested DAILY

• Vitamin C

• B-Complex

Vitamin C (what it does, found in what)

• immune system “booster” → anti-cancer vitamin

• Found in citrus fruit, tomatoes, white potatoes

B-Complex (what it does, found in what)

• Guards the nervous system → longer life expectancy (correlated w/brain sharpness)

• Found in dairy products, meats, veggies