Digestive System

Question 1

What are the digestive system functions?

Answer 1

• Ingestion
• Propulsion
  Swallowing, peristalsis
• Mechanical breakdown
  Chewing, churning, segmentation
• Chemical digestion
  Mouth, stomach, small intestine
• Absorption
• Defecation

Question 2

Oral Cavity

Answer 2

Mouth
– Entrance to GI tract
– Stratified squamous epithelium
* No keratin
* Layers protect against abrasion
* Moistened with saliva

• Vestibule
  – Between lips and teeth
• Oral cavity
  – Behind teeth

Question 3

Labial frenulum

Answer 3

Where the internal surfaces of the lips attach to gingiva with a thin, midline mucosa fold

Question 4

Palates

Answer 4

– Hard palate
* Underlain by bone
* Tongue forces food against it
during chewing

– Soft palate
* Mostly skeletal muscle
* Rises to nasopharynx during
swallowing
* Contains palatine tonsils

Question 5

Fauces

Answer 5

Opening from the oral cavity to
the oropharynx

Question 6

Palatoglossal arch

Palatopharyngeal arch

Answer 6

(anterior)

(posterior)

Question 7

What do the intrinsic and extrinsic muscles in the tongue do?

Answer 7

Intrinsic muscles
– At tip
– Allows shape change (like curling or
flattening)

Extrinsic muscles
– Alters tongue position (like protrusion,
retraction, and side-to-side adjustments)

Question 8

Lingual frenulum

Answer 8

Secures tongue to floor of mouth

Question 9

Salivary glands

Answer 9

Parotid
– Anterior to ear
– Infected in mumps

• Submandibular
  – Next to mandible
• Sublingual
  – Anterior to mandible
• Buccal glands
  – Small intrinsic salivary glands

Question 10

Describe the roles of serous and mucous cells in salivary glands.

Answer 10

Serous cells
* Watery secretions (97-99.5%) containing enzymes

– Mucous cells
* Mucus
– Production
* Continuous
* PNS increases

Question 11

What are the functions of the salivary glands?

Answer 11

– Cleanses mouth
– Dissolves food
– Allows for taste
– Aids compaction of food into bolus
– Begins breakdown of food with enzymes

Question 12

Roots of teeth

Answer 12

Fit into dental alveoli (sockets)
– connected to jaw bone with periodontal ligaments
– Each root is covered with hard cementum

Question 13

Dentin

Answer 13

Forms primary mass of a tooth

Question 14

Pulp cavities

Answer 14

The center of the tooth is a pulp cavity that contains connective tissue called pulp.

Root canal is continuous with pulp cavity and opens at apical foramen. Blood vessels and nerves pass through this opening and are
housed in the pulp.

Question 15

Pharynx

Answer 15

Oropharynx and laryngopharynx
* nonkeratinized stratified squamous lining

• Pharyngeal constrictors (Muscles) within its wall participate in swallowing
• Superior, middle, and inferior
• CN X innervates most pharyngeal muscles

Question 16

Peritoneum

Answer 16

Visceral peritoneum
– Covers organs

Parietal peritoneum
– Lines walls of abdominal cavity

Peritoneal cavity
– Filled with serous fluid

Intraperitoneal
– Organs located within the
peritoneal cavity.

Retroperitoneal
– Behind parietal peritoneum
– Against the dorsal abdominal
wall

Question 17

Mesentery

Answer 17

– Connects visceral & parietal peritoneum
– Provides routes for blood vessels, nerves, lymphatics
– Holds organs in place

Question 18

Four tunics of GI organs

Answer 18

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

Question 19

Mucosa

Answer 19

– Lines lumen from mouth to anus
– Secretes mucus, enzymes, hormones
– Absorbs digestive products
– Protects against disease

Surface epithelium
– Simple columnar

Lamina propria
– Areolar connective tissue
– Capillaries
– Lymphatics

Muscularis mucosae
– Smooth muscle

Question 20

Other layers

Answer 20

Submucosa
– Dense irregular connective tissue
with elastic fibers

• Muscularis
  – Responsible for peristalsis
  – Layers
• Inner circular
• Outer longitudinal
  – Sphincters
• Thickened parts of inner layer
• Control passage of foods
• Serosa
  – Areolar connective tissue
  – Collegen and elastin fibers
  – Adventia in retroperitoneal organs

Question 21

The cells of the stomach mucosa are

Answer 21

Simple columnar epithelium

Question 22

Parietal cells

Answer 22

• Secrete HCl
• Gives stomach pH 1.5-3.5
• Kills bacteria

Question 23

Chief cells

Answer 23

Produces pepsin (Chemical
digestion)

Question 24

Enteroendocrine cells

Answer 24

Release gastrin

Question 25

Mucous neck cells

Answer 25

Secrete mucus

Question 26

Mucosal barrier

Answer 26

– Prevents stomach from digesting itself
– Thick alkaline mucus
– Epithelial cells with tight junctions
– Epithelial cells replaced in 3-6 days

Question 27

What is the end of the ileum?

Answer 27

ileocecal valve

Question 28

What is the mucosa of the small intestine?

Answer 28

simple columnar

Question 29

Submucosal glands in the small intestine

Answer 29

Alkaline mucus neutralizes acidic chyme

Question 30

What are the functions of the large intestine?

Answer 30

– Absorption of water
– Elimination of solid waste

Question 31

What are the subdivisions of the large intestine?

Answer 31

Cecum
* Sack-like first part

Veriform Appendix
* Masses of lymphoid tissue

Colon
* Ascending
* Transverse
* Descending
* Sigmoid

Rectum
* 3 internal transverse folds
– Rectal valves
– Separate feces from flatus (gas)

Anus
– Has two sphincters
* Internal anal sphincter
– Involuntary
– Smooth muscle
* External anal sphincter
– Skeletal muscle

Question 32

Liver

Answer 32

– Largest gland in body
– Under diaphragm on right
side
– 4 primary lobes
* Right & Left – major lobes
* Caudate
* Quadrate

Question 33

Liver ligaments

Answer 33

Falciform ligament
* Mesentery that suspends liver
from diaphragm

Round ligament
* Fibrous remnant of fetal
umbilical vein

Question 34

Hepatic…

Answer 34

Hepatic portal vein
* carries nutrient-rich blood from GI
tract, spleen and pancreas to liver
* Hepatic artery proper
* carries oxygen-rich blood to the
liver
* splits into left and right hepatic
arteries
* Hepatic veins empty into inferior
vena cava
Accessory Organs

– Hepatic lobule
* Hepatocytes
* Radiate around central vein
* Portal Triad
– Bile duct
– Hepatic artery
– Hepatic portal vein

Question 35

Hepatocytes

Answer 35

– Produce bile
– Process blood borne nutrients
» Glucose from / to glycogen
– Store fat
– Play role in detoxification

Question 36

Gallbladder

Answer 36

– At inferior margin of liver
– Stores and concentrates bile
– Sphincter at neck releases bile

Question 37

Pancreas

Answer 37

– Acini
* Exocrine
* Secretory cells of pancreas
* Pancreatic juice

– Islets of Langerhans
* Endocrine gland