Gastrointestinal

Question 1

Ingestion

Answer 1

Acquisition of nutrients

Question 2

Digestion

Answer 2

Mechanical and chemical breakdown of ingested food

Question 3

Propulsion

Answer 3

Movement of food through GI tract (peristalsis and segmentation)

Question 4

Secretion

Answer 4

Release of mucin, water, acid, and enzymes into the lumen of the digestive system

Question 5

Absorption

Answer 5

Transport of nutrients from the digestive system to the circulatory system

Question 6

Defecation

Answer 6

Elimination of feces

Question 7

Parietal Peritoneum

Answer 7

Lines inner surface of body wall; is attatched to abdominal and pelvic walls; secretes peritoneal fluid and stores fat

Question 8

Visceral Peritoneum

Answer 8

Wrapped around the organs within the Intraperitoneal space

Question 9

Mesenteries

Answer 9

Folds of peritoneum that support the intraperitoneal GI tract organs; contains vessels, nerves and lymphatics

Question 10

Intraperitoneal Organs

Answer 10

Organs suspended into the peritoneal cavity that are movable and contain mesenteries

Question 11

Retroperitoneal Organs

Answer 11

Organs not suspended into the peritoneal cavity that are immobile and lack mesenteries

Question 12

Hepatic Portal System

Answer 12

A network of veins that carries blood from the GI trct and spleen to the liver

Question 13

Esophagus

Answer 13

Hollow 25cm muscular tube connecting the pharynx tto the stomach

Question 14

Liver

Answer 14

Removes and adds compounds to the blood as it circulates through the lobule

Question 15

Gallbladder

Answer 15

• Concentrates bile produced by the liver - absorbs Na+ and Cl- and water by osmosis
• Stores up to 450mL of bile (12hrs worth)
• Releases bile upon stimulation (PNS & CCK)

Question 16

Pancreas

Answer 16

Produces hormones and enzymes

Question 17

Epithelial cells sense the contents of the GI lumen via,

Answer 17

• Chemoreceptors
• Osmoreceptors
• Stretch receptors

Question 18

Steps of Swallowing

Answer 18

1. Bolus in mouth and upper esophageal sphincter is closed
2. Glottis moves upward and closes and Epiglottis moves dowward and covers glottis
3. Upper esophageal sphincter opens
4. Wave of peristalsis travels along esophagus and upper esophageal sphincter closes
5. Lower esophageal sphincter opens
6. Secondary wave of peristalsis in esophagus.

Question 19

Coordination of Muscular Contractions in Peristalsis

Answer 19

1. Contraction of circular muscles behind food mass
2. Contraction of longitudinal muscles ahead of food mass
3. Contraction of circular muscle layer forces food mass forward.

Question 20

Frequency and Amplitude of Peristalsis

Answer 20

Regulated by:

• Body temp and metabolic activity
• ENS and ANS
• Hormones eg. CCK

Question 21

ENS

Answer 21

• Intrinsic

- Extrinsic

Question 22

ANS

Answer 22

• Parasympathetic

- Sympathetic

Question 23

Phases of Digestion

Answer 23

1. Cephalic phase
2. Gastric phase
3. Intestinal phase

Question 24

Cephalic Phase

Answer 24

Prepares stomach for food:

• Short (min)
• Mechanism: neural
• Actions: stimulation of mucus, enzyme and acid production –> increased volume of gastric juice

Question 25

Gastric Phase

Answer 25

Stomach acts on food: - Long (3-4hrs) - Mechanisms: Neural, hormonal, local - Actions: Chemical and mechanical digestion

Question 26

Stomach

Answer 26

- Mechanical digestion and mixing of Proteins (HCl, Pepsinogen) and Fats (Gastric lipase) - Storage 50mL-1.5L - No absorbtion (except aspirin and alcohol)

Question 27

Layers of Stomach Muscularis Externa

Answer 27

1. Inner oblique 2. Middle circular 3. Outer longitudinal

Question 28

Regions of Small Intestine

Answer 28

- Duodenum - Jejunum - Ileum

Question 29

Small Intestine

Answer 29

The longest component of the GIT, Begins at pyloric sphincter and ends at ileocecal valve Function: - Digestion - Absorbtion

Question 30

Duodenum

Answer 30

'C' shaped tube - Mixing bowl - Chyme with bile and pancreatic secretions - Longitudinal and circular smooth muscle - Mucous membrane lining to buffer stomach acid

Question 31

Secretions in Duodenum

Answer 31

Secretin and CCK control: - Gastric emptying - Accessory organs (Pancreas, gallbladder, liver)

Question 32

Exocrine Pancreas Contains...

Answer 32

- Digestive enzymes - Digestive enzymes as zymogens (inactive) - Lipases and bile salts are pH sensitive

Question 33

Digestive Enzymes

Answer 33

- Proteolytic enzymes - Pancreatic lipase - Pancreatic amylase

Question 34

Digestive Enzymes as Zymogens (Inactive)

Answer 34

- Trypsinogen is activated by enteropeptidase | - Trypsin then activates other symogens

Question 35

Lipases and bile salts are PH sensitive

Answer 35

- CF (Insufficient alkali) - Gastrinomas (Excess acid production) - Staeterrhea = fatty stools

Question 36

Hepatic Portal System

Answer 36

- Liver recieaves all blood that passes through the stomach and intestines - Metabolising gatekeeper (liver detox fads) - Nutrient rich and oxygen poor

Question 37

Detailed Functions of the Liver

Answer 37

- Metabolism of: carbohydrates, lipids, proteins - Storage of vitamins and minerals - Processing of drugs and hormones - Phagocytosis of RBC, WBC and bacteria - Makes bile

Question 38

Bile Acids

Answer 38

Synthesised from cholesterol

Question 39

Bile Contents

Answer 39

- Bile acids - Water - Ions - Cholesterol - Phospholipids - Bilirubin

Question 40

Gallstones

Answer 40

Crystallisation of bile

Question 41

Jejunum and Ileum

Answer 41

Primary sites of absorption

Question 42

Absorption of Electrolytes With Monosaccharides and Amino Acids

Answer 42

- All uses secondary active transport - Nutrient absorption matched by Na+ absorption - Matched to water absorption via osmosis

Question 43

Large Intestine

Answer 43

- Extends from ileocecal sphincter to anus | - Tonic contraction of longitudinal muscles form pouches

Question 44

4 Divisions of Large Intestine

Answer 44

1. Caecum 2. Colon 3. Rectum 4. Anal canal

Question 45

Colon Physiology

Answer 45

- Storage - Absorption of water and electrolytes - Gablet cells (Mucous lubricate faeces and secrete HCO3) - Bacteria ferment undigested carbohydrates and produce acid

Question 46

Bacteria Support Immune and Antioxidant Functions

Answer 46

- >700 species in large intestine - Bacterial gas = N2, CO2, CH4, H2, H2S - approx. 30% faecal mass is bacteria

Question 47

Colon Motility

Answer 47

- Low Frequency segmentation (mixing) | - Mass movements - contraction wave toward distal colon

Question 48

Defacation Reflex

Answer 48

- Mass movements (faecese to rectum) - Distention - Internal sphincter relaxes - Colon contracts - External anal sphincter controls defecation