Digestive System - Tutorial 1

Question 1

Name & describe the nine regions & four quadrants of the abdominopelvic cavities

Answer 1

• Nine regions of abdominopelvic cavity (from top left to right)
• Right Hypochondriac region - Epigastric region
• Left Hypochondriac region
• Right Lumbar (flank) region
• Umbilical region
• Left Lumbar (flank) region
• Right Iliac (inguinal) region
• Hypogastric (pubic) region
• Left iliac (pubic) region
• 4 quadrants of abdominopelvic cavity (from top left to right)
• Right Upper Quadrant (RUQ)
• Left Upper Quadrant (LUQ)
• Right Lower Quadrant (RLQ)
  Left Lower Quadrant (LLQ)

Question 2

Name & describe the six digestive system processes

Answer 2

1. Ingestion: Taking food into the mouth
2. Motility: the mixing of peristalsis (= propulsion of food by alternating waves of contraction and relaxation of smooth muscle in walls of the GI tract).
3. Secretion: 7L of water, acid, buffers, enzymes into the lumen of the GI tract.
4. Digestion:
   
   • Mechanical - breakdown in mouth by biting, chewing stomach and small intestine by churning and mixing food
   • Chemical - breakdown by enzymes into small molecules
5. Absorption: movement of molecules into epithelial cells lining the GI tract and into blood and lymph
6. Defecation: elimination of faeces (wastes, ingestible substances, bacteria, epithelial cells)
   ELIMINATION

Question 3

Name the four layers of the digestive tract in the correct sequence from innermost to
outer layer.

Answer 3

1. Mucosa
2. Submucosa
3. Muscularis
4. Serosa

Question 4

Describe the function of each layer

Answer 4

1. Mucosa
   - Secrete mucus, digestive enzymes and hormones
   - Absorb products of digestion
   - Protect against disease
2. Submucosa
   - Contains blood and lymphatic vessels to receive absorbed nutrients
   - Nerves to control the GI tract
3. Muscularis
   - Mixing and peristalsis of contents of lumen
   - Contains sphincters: thicken rings of circular smooth muscle surrounding an opening that acts as valves
   - Skeletal muscle is present in mouth, pharynx upper oesophagus and anal sphincter for voluntary ingestion, swallowing and defecation.
4. Serosa
   Allow movement of organs inside the abdominal cavity without friction

Question 5

State the tissue type of each layer (this connects with the function)

Answer 5

1. Mucosa - moist epithelial inner layer that lines GI tract from mouth to anus
2. Submucosa - areolar connective tissue binds mucosa to muscularis
3. Muscularis - an inner circular and outer longitudinal layer of smooth muscle
4. Serosa - connective tissue layer, and visceral peritoneum

Question 6

Name the three layers of the peritoneum in the correct sequence, deep to superficial

Answer 6

• Visceral layer - covers organs
• Peritoneal cavity - contains serous fluid
• Parietal layer - lines the abdominopelvic cavity

Question 7

State four functions of the tongue

Answer 7

• Taste
• Manipulates food for chewing
• Aids swallowing
• Articulates speech

Question 8

State the health risks associated with tooth & gum disease

Answer 8

Causes chronic inflammation which increases risk of heart disease and stroke

Question 9

State two functions of saliva

Answer 9

• Cleans the mouth and teeth
• Soften, moisten and dissolve food

Question 10

Name the four contents of saliva & give a function for each

Answer 10

Water - dissolves foods to begin the digestive process and stimulates taste buds

Amylase - digests starch to maltose

Mucus - lubricates the food for movement and swallowing

Lysozyme - helps destroy bacteria

Question 11

Define gingivitis & halitosis

Answer 11

Gingivitis - inflammation of the gums
Halitosis - bad breath

Question 12

State the location & function of the epiglottis

Answer 12

The epiglottis covers the larynx and there is involuntary movement of the bolus from the oropharynx to the oesophagus

Question 13

State the function of the oesophagus

Answer 13

Secretes mucus and transports the bolus to the stomach by peristalsis

Question 14

State the specific function of HCL & mucus in the stomach

Answer 14

Hydrochloric acid (HCI) - kills microbes in food

Mucus - protects stomach wall from being damaged by the HCI

Question 15

Describe the homeostatic imbalances that can occur with prolonged or severe
vomiting

Answer 15

Excess vomiting can cause dehydration and disrupt the electrolyte and pH balance. As acid is lost the blood becomes more alkaline.