9.1 Digestion 1

Question 1

What is the difference between malabsorption and malnutrition?

Answer 1

malabsorption: inability to transport nutrients or fluids from the GI tract to the blood
malnutrition: inability to obtain necessary nutrients; lack of supply, poor diet, lack of nutrient processing

Question 2

What are segmentation and mass movement?

Answer 2

Segmentation- small intestine only: chunks up food, mostly circular muscles- increases enzymatic contact and more mechanical breakdown

Mass movements- large intestine/bowel; all coordinate to squeeze/move large amounts of material out for elimination

Question 3

How are carbs digested and absorbed?

Answer 3

Digestive enzymes: salivary amylase, pancreatic amylase, brush border enzymes
Absorption: small intestine transport is across villi into blood via secondary active transporters

Question 4

How are proteins digested and absorbed?

Answer 4

Digestion: pepsin, trypsin, chymotrypsin, carboxypeptidase, brush border enzymes
Absorption: small intestine transport is across villi into blood via secondary active transporters

Question 5

How are fats digested and absorbed?

Answer 5

Emulsified by bile salts

Fat globules-> micelles -> vesicle-like system -> chylomicrons -> lacteal

Question 6

What are the digestive organs?

Answer 6

Oral cavity
Pharynx
Esophagus
Stomach
Small Intestine
Large intestine

Question 7

What are the accessory digestive organs?

Answer 7

Salivary glands
Liver
Pancreas
Gallbladder

Question 8

What are the linings within the abd/pelvic cavity?

Answer 8

Parietal peritoneum – serous membrane, lines wall of the abdominal cavity
Visceral peritoneum –serous membrane, lines abdominal organs
Peritoneal cavity – contains serous fluid

Question 9

What is the structure and function of mesentery?

Answer 9

a double-layered sheet of peritoneum surrounding some digestive organs
holds digestive organs to the body wall
contains blood vessels, lymph, and nerves
stores fat

Question 10

What divides the liver, attaches to body wall?

Answer 10

Falciform ligament

Question 11

What are the greater/lesser omentum?

Answer 11

Lesser Omentum: ventral, liver to lesser curvature (top) stomach
Greater Omentum: ventral, greater curvature (lower) stomach to transverse colon, also covers small intestine

Question 12

What is the mesentery proper?

Answer 12

dorsal, connects small intestine to back body wall

Question 13

What is the mesocolon?

Answer 13

mesentery that connects colon to back body wall
transverse mesocolon
sigmoid mesocolon

Question 14

What are common causes of peritonitis?

Answer 14

bacterial infection
leakage of intestinal or other organ contents into peritoneal cavity
bacteria
bile
stomach acid
traumatic injury

Question 15

What are complications of peritonitis?

Answer 15

peritoneal fluid shift, excess fluid causes peritoneal edema, decreased blood volume, electrolyte imbalance

secondary complications:
abdominal abscess
paralytic ileus – lack of intestinal motility
cardiac arrythmia
intestinal perforation
septicemia
hypovolemic shock

Question 16

What is the blood supply of the mesenteries?

Answer 16

The Splanchnic Circulation: branches of arteries from abdominal aorta to digestive organs
Hepatic Portal Circulation: blood draining from abdominal organ veins to liver before returning to inferior vena cava

Question 17

What is the enteric nervous system? What are it’s nerve plexuses? Where are they located?

Answer 17

The “gut brain” semi-autonomous network of neurons within the digestive system with pacemaker cells and local reflex arcs
Submucosal Plexus: beneath, within epithelial, glandular layers
Myenteric Nerve Plexus: between smooth muscle layers

Question 18

What are the PNS/SNS innervations of the gut?

Answer 18

Parasympathetic input:
Vagus Nerve (CN X)
Pelvic Splanchnic Nerves
Sympathetic input:
Thoracic Splanchnic Nerves
Sacral Splanchnic Nerves

Question 19

What are the 4 layers of gut wall?

Answer 19

Mucosa
Submucosa
Muscularis
Serosa- serous covering in peritoneum; Adventitia if retroperitoneal

Question 20

What are the 2 sphincters in the esophagus? Where are they? Open/closed?

Answer 20

pharyngoesophageal (upper) sphincter prevents aspiration, directs food away from airways (contracted at rest
gastroesophageal (cardiac, lower) sphincter (contracted at rest)

Question 21

What ate the 2 stages of deglutition?

Answer 21

Voluntary: Oropharyngeal Phase (skeletal muscle)
Tongue propels the food bolus into the pharynx
Respiratory passages are closed off by uvula, upper esophageal sphincter and epiglottis
Bolus moves from pharynx to esophagus
Involuntary: Pharyngoesophageal Phase (smooth muscle)
Bolus moves from esophagus to stomach through cardiac sphincter via peristalsis waves
Respiratory passages can re-open

Question 22

How can neuromuscular dysfunction cause dysphagia?

Answer 22

lack of gag reflex due to cranial nerve dysfunction, stroke, degenerative neurological conditions, spinal cord injury, trauma

Question 23

How can structural abnormalities cause dysphagia?

Answer 23

tumors
congenital diverticulum – outpouching of wall
congenital or acquired connective tissue rings around esophagus
congenital or acquired stricture – thinning or narrowing

Question 24

What is achalasia?

Answer 24

cardiac spasm, surgery may be needed to prevent dysphagia from progressing to aspiration
decreased peristalsis, increased tone, contracted cardiac sphincter