C5: Digestive System

Question 1

describe the digestive system

Answer 1

CHECK FOLDER

Question 2

what 9 organs are part of the alimentary canal?

Answer 2

1. mouth
2. esophagus
3. cardiac sphincter
4. stomach
5. pyloric sphincter
6. small intestine
7. ileocecal valve
8. large intestine
9. anal sphincter

Question 3

for the mouth,
- what is its structure?
- function?
- secretions?

Answer 3

-oral cavity, teeth tongue
- mechanical digestion (chewing), chemical digestion (saliva)
- saliva

Question 4

for the esophagus,
- what is its structure?
- function?
- secretions?

Answer 4

• muscular tube, skeletal muscle at top (voluntary), transitions to smooth muscle (involuntary)
• peristalsis (method of contraction that moves things down the esophagus) of bolus down
• none

Question 5

for the cardiac sphincter,
- what is its structure?
- function?
- secretions?

Answer 5

• smooth muscle
• prevents chyme going up the esophagus
• none

Question 6

for the stomach,
- what is its structure?
- function?
- secretions?

Answer 6

• 3 layers of smooth muscle, gastric pits/glands for secretions
• chemical digestion of proteins (pepsin), low pH (to kill pathogens), mechanical digestion (churning), storage (major function!! stores food)
• low pH (HCl) promotes gastric secretions and motility

Question 7

for the pyloric sphincter,
- what is its structure?
- function?
- secretions?

Answer 7

• smooth muscle
• releases chyme, a squirt at a time
• none

Question 8

for the small intestine,
- what is its structure?
- function?
- secretions?

Answer 8

• duodenum, jejunum, ileum
• chemical digestion, absorption
• 3 duodenal hormones, brush border peptidases and disaccharides

Question 9

for the ileocecal valve,
- what does it connect?
- what is its structure?
- function?
- secretions?

Answer 9

• ileum and cecum
• smooth muscle
• regulates small to large intestine
• none

Question 10

for the large intestine,
- what is its structure?
- function?
- secretions?

Answer 10

• cecum, colon, rectum
• water and mineral absorption, home of e. coli, stores and concentrates feces
• none

Question 11

for the anal sphincter,
- what is its structure?
- function?
- secretions?

Answer 11

• internal= smooth muscle (involuntary), external= skeletal muscle (voluntary)
• regulates defecation
• none

Question 12

the small intestine has a huge surface area due to what 4 things?
- how do chemical digestion and absorption occur within the small intestine?

Answer 12

1. length
2. plicae/ folds
3. villi (finger-like projections)
4. microvilli (plasma membrane extensions)
   - (more chemical digestion) duodenum > jejunum > ileum (less chemical digestion). opposite for absorption

Question 13

what are the 4 accessory organs?

Answer 13

1. salivary glands
2. liver
3. gallbladder
4. pancreas

Question 14

what does saliva contain?

Answer 14

water, mucus, salivary amylase (starch chemical digestion), salivary lipase (fat chemical digestion), lysozyme (breaks down the bacterial cell wall)

Question 15

what are the 4 main functions of the liver?
- what is the only digestive function of the liver?

Answer 15

1. storage: glycogen, iron, vitamins
2. metabolic pathways
3. detoxification: toxins, drugs, alcohol, hormones, rbc recycling
4. synthesis: plasma proteins, bile, cholesterol and lipids
   - bile production

Question 16

what is the function of the gallbladder?

Answer 16

stores and concentrates bile

Question 17

in the pancreas,
- what is its exocrine tissue?
- what does it (the exocrine tissue) make?
- release?
- what is the pancreas’ endocrine tissue?
- describe what this means

Answer 17

• acini
• makes bicarbonate (neutralizes stomach acid and duodenum), digestive enzymes (proteases: proteins, nucleases: nucleic acids, lipases: lipids, amylases: carbohydrates)
• releases secretions into the duodenum via the pancreatic duct
• islets of langerhans
• alpha cells: glucagon to increased glucose; beta cells: insulin to decreased glucose; gamma cells: somatostatin to decreased gastric motility