MBS 217 Lecture 4 and 5

Question 1

What does the digestive system anatomy consists of:

Answer 1

Digestive tract
Accessory organs
Regions

Question 2

Accessory organs are also known as

Answer 2

Primarily glands

Question 3

Functions of the digestive system

Answer 3

Ingestion: Introduction of food into stomach
Mastication: Chewing
Propulsion: Deglutition: Swallowing
: Peristalsis: Moves material through digestive tract

Mixing: Segmental contraction that occurs in small intestine
Secretion: Lubricate, liquefy, digest
Digestion: Mechanical and chemical
Absorption: Movement from tract into circulation or lymph
Elimination: Waste products removed from body

Question 4

Structure of the lingual fenulum

Answer 4

The base of the frenulum contains a v shaped hump of tissue in the floor of the mouth, which houses a series of saliva gland ducts.
The two largest ducts are in the center just in front of the attachment of the lingual frenulum and are calledWharton’s ducts. They empty the submandibular submaxillary and sublingual glands

Question 5

Functions of the salivary glands

Answer 5

• Prevents bacterial infection
  – Lubrication
  – Contains salivary amylase
• Breaks down starch

Question 6

Name the salivary glands

Answer 6

Parotid: Largest
– Submandibular
– Sublingual: Smallest

Question 7

Structure of parotid glands

Answer 7

Parotid glands have mainly serous acini; producing large
amounts of salivary amylase; secretions drained by the
Stensen duct emptying at the vestibule at level of upper
molar.

Question 8

sf

Question 9

Structure of sublingual glands

Answer 9

Sublingual glands have mainly mucous acini; act as buffer
and lubricant; sublingual ducts (Rivinus ducts) open either
side of the lingual frenelum.
The sublingual gland is inferior to the mucosa of the floor
of the mouth and is anterior to the deep process of the
submandibular gland.

Question 10

Structure of Submandibular glands

Answer 10

Submandibular glands have a mixture of mucous and
serous acini.
Secrete a mixture of buffers, glycoproteins (mucins) and
salivary amylase
Submandibular ducts (Whartons ducts) open on either side
of the lingual frenelum immediately posterior to the teeth

Question 11

Composition of saliva

Answer 11

Salivary glands produce about 1.5 liters of saliva
daily
– 99% water
– 0.6 % electrolytes (Na, Cl, HCO 3 Buffers, glycoproteins, antibodies and waste products).

Question 12

Function of salivary amylase

Answer 12

Salivary amylase (ptyalin) begins to break down
starch (inactivated in the stomach)

Question 13

Function of Salivary lipase:

Answer 13

begins fat digestion, but has
minimal effect

Question 14

Function of Glycoproteins (Mucins)

Answer 14

to lubricate the food for easier swallowing

Question 15

Function of Lysozyme

Answer 15

Lysozyme to kill bacteria

Question 16

Percentage of secretion of each gland

Answer 16

70% of saliva originate in the submandibular
salivary gland
– 25% parotid
– Remaining in the sublingual

Question 17

What does saliva do in the mouth

Answer 17

Continuous level of saliva flushes oral surfaces
keeping clean
Prevent build upon of acids and bacterial action

Question 18

pH of buffer in mouth

Answer 18

7

Question 19

What controls oral bacteria (stress, radiation etc causes reduction and explosion of bacteria in oral cavity)

Answer 19

Antibodies IgA and Lysozyme which c

Question 20

Control of salivary secretion

Answer 20

Autonomic nervous system

Question 21

What are the secretion glands innervated by

Answer 21

sympathetic and parasympathetic nerves

Question 22

Function of the villus

Answer 22

Blood supply in the villus which absorb the end products of digestion from the epithelial cells

Question 23

Parasympathetic is stimulated by

Answer 23

trigeminal nerve or taste buds innervated by cranial nerve VII,
IX, X.

Question 24

Function of Parasympathetic stimulation

Answer 24

speeds up secretion (feed and breed)

Question 25

Pharynx

Answer 25

Nasopharynx – Oropharynx: Transmits food normally – Laryngopharynx: Transmits food normally

Question 26

Esophagus

Answer 26

Transports food from pharynx to stomach – Passes through esophageal hiatus (opening) of diaphragm and ends at stomach * Hiatal hernia – Sphincters * Upper * Lower

Question 27

Structure of the colon

Answer 27

- The lumen of the colon - The mucus producing goblet cells - Muscular walls to maintain peristalsis

Question 28

Increase surface area of the Gut lumen

Answer 28

The inner intestine wall is folded which increases the available surface area by three times. The villi are finger like projections into the lumen of the gut. These increase the available surface area by ten times. Microvilli increases further

Question 29

Function of the lacteals

Answer 29

The lacteals (green) that receive the lipoproteins before transporting them to the circulatory system.

Question 30

Function of the muscular walls

Answer 30

Muscular walls that maintain the movement of chyme by peristalsis.

Question 31

How does microvilli increase surface area

Answer 31

The cell membrane of the epithelial cells is folded into microvilli. This increases the available surface area still further

Question 32

Histology of stomach

Answer 32

Layers – Serosa or visceral peritoneum: Outermost – Muscularis: Three layers * Outer longitudinal * Middle circular * Inner oblique – Submucosa – Mucosa * Rugae: Folds in stomach when empty * Gastric pits: Openings for gastric glands – Contain cells * Surface mucous: Mucus * Mucous neck: Mucus * Parietal: Hydrochloric acid and intrinsic factor * Chief: Pepsinogen * Endocrine: Regulatory hormones

Question 33

Modifications of the small intestine

Answer 33

Circular folds or plicae circulares, villi, lacteal, microvilli

Question 34

What are the types of cells of mucosa

Answer 34

Absorptive, goblet, granular, endocrine

Question 35

What are the secretions of the small intestine

Answer 35

* Mucus – Protects against digestive enzymes and stomach acids * Digestive enzymes – Disaccharidases: Break down disaccharides to monosaccharides – Peptidases: Hydrolyze peptide bonds – Nucleases: Break down nucleic acids * Duodenal glands – Stimulated by vagus nerve, secretin, chemical or tactile irritation of duodenal mucosa

Question 36

Lobes of the liver

Answer 36

Major: Left and right Minor: Caudate and quadrate

Question 37

Ducts of the Liver

Answer 37

Common hepatic Cystic From gallbladder Common bile Joins pancreatic duct at hepatopancreatic ampulla

Question 38

Functions of the Liver

Answer 38

Bile production – Salts emulsify fats, contain pigments as bilirubin Storage – Glycogen, fat, vitamins, copper and iron Nutrient interconversion Detoxification – Hepatocytes remove ammonia and convert to urea Phagocytosis – Kupffer cells phagocytize worn-out and dying red and white blood cells, some bacteria Synthesis – Albumins, fibrinogen, globulins, heparin, clotting factors

Question 39

Gallbladder

Answer 39

Bile is stored and concentrated

Question 40

What is the gallbladder stimulated by

Answer 40

Stimulated by cholecystokinin and vegal stimulation

Question 41

Anatomy of the Pancreas - Endocrine

Answer 41

Pancreatic islets produce insulin and glucagon

Question 42

Anatomy of the Pancreas - Exocrine

Answer 42

Acini produce digestive enzymes

Question 43

Secretions of the pancreas

Answer 43

Pancreatic juice (exocrine) * Trypsin * Chymotrypsin * Carboxypeptidase * Pancreatic amylase * Pancreatic lipases * Enzymes that reduce DNA and ribonucleic acid

Question 44

Structure of Large intestine

Answer 44

Cecum – Blind sac, vermiform appendix attached Colon – Ascending, transverse, descending, sigmoid Rectum – Straight muscular tube Anal canal – Internal anal sphincter (smooth muscle) – External anal sphincter (skeletal muscle) – Hemorrhoids: Vein enlargement or inflammation

Question 45

Secretions of Large Intestine

Answer 45

* Mucus provides protection – Parasympathetic stimulation increases rate of goblet cell secretion * Pumps – Exchange of bicarbonate ions for chloride ions – Exchange of sodium ions for hydrogen ions * Bacterial actions produce gases called flatus

Question 46

Movement in large intestine

Answer 46

Mass movements – Common after meals Local reflexes in enteric plexus – Gastrocolic: Initiated by stomach – Duodenocolic: Initiated by duodenum Defecation reflex – Distension of the rectal wall by feces Defecation – Usually accompanied by voluntary movements to expel feces through abdominal cavity pressure caused by inspiration

Question 47

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Answer 47

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Question 48

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Answer 48

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