Chapter 22: The Digestive System

Question 1

Alimentary Canal

Answer 1

Gastrointestinal (GI) tract

Question 2

Alimentary Canal Structural Components: Digestive Organs

Answer 2

Mouth
Pharynx
Esophagus
Stomach
Small and Large Intestines
Anus

Question 3

Alimentary Canal Structural Components: Accessory Digestive Organs

Answer 3

Teeth
Tongue
Salivary Glands
Liver
Gall Bladder
Pancreas

Question 4

Digestive Process

Answer 4

1. Ingestion: intake food
2. Propulsion: movement of food by swallowing and peristalsis
3. Mechanical Digestion: chewing, churning and segmentation (local rhythmic constrictions) food
4. Absorption: transport of digested products from lumen into blood and lymph capillaries
5. Defecation: elimination of undigested food substances

Question 5

Abdominal Regions

Answer 5

• Abdominal organs will move
• Abdominal regions aid in locating organs
• Hypochondriac
• Epigastric
• Hypogastric

Question 6

Hypochondriac

Answer 6

deep to the ribs

Question 7

Epigastric

Answer 7

superior to the belly

Question 8

Hypogastric

Answer 8

inferior to the belly

Question 9

Peritoneal Cavity and Peritoneum

Answer 9

Peritoneum: which will cover and line abdominopelvic cavity

Layers:

• Visceral peritoneum: covers external surface or digestive organs
• Pariteal Peritoneum: lines the walls of cavity
• Space contains serous fluid to allow organs to move against one another

Question 10

Mesentereies

Answer 10

• Double layer of peritoneum; serous membranes fused together
• Will extend to digestive organs from body wall to hold organs in place
• Fat storage
• Support vessels and nerves to reach organs

Question 11

Ventral Mesenteries

Answer 11

• Falciform Ligament: anterior of liver to anterior abdominal wall and diaphragm
• Lesser omentum (fatty skin)-runs from liver fissure to lesser curvature

Question 12

Dorsal Mesenteries

Answer 12

Greater momentum (fatty skin) - cover intestines

Question 13

Mouth Functions

Answer 13

ingest, mechanical digest and chemically digest

Question 14

Boundaries of the Mouth

Answer 14

• Anterior-lips
• Posterior-fauces of oropharynx
• Lateral-cheecks
• Interior-tongue
• Superior-palates

Question 15

Structures of the Mouth

Answer 15

• Vestibule: space external to teeth

- Oral cavity proper: space internal to teeth

Question 16

Salivary Glands Produce:

Answer 16

Saliva

Question 17

Functions of Saliva

Answer 17

• moistens mouth
• dissolves food chemically-starches
• binds food together to blue
• neutralizes acids produced by oral bacteria to prevent tooth decay
• bactericidal enzymes

Question 18

Glands

Answer 18

paired compound tubuloalveloar glands

1. Parotid: “near ear”
2. Submandibular: medial surface of mandibular body
3. Sublingual: inferior to tongue

Question 19

The Pharynx

Answer 19

• bolus leaves mouth enters oropharynx and laryngopharynx

- pharynx is continous with esophagus

Question 20

Esophagus

Answer 20

food to stomach

• Lumen collapses when no food is present
• Passes through diaphragm: esophageal hiatus
• Joins stomach at cardiac orifice where the cardiac sphincter closes off lumen to prevent regurgitation

Question 21

The Stomach Functions

Answer 21

• temporary storage for food
• chum food into chin paste
• starts breakdown of food proteins by secreting pepsin which functions only under acidic conditions
• absorbs water, electrolytes and some drugs

Food remains in stomach for about 4 hours

Question 22

Structures of the Stomach

Answer 22

• Cardiac Region (Cardia): near the heart
• Fundus
• Body
• Pyloric Region: Pylorus and Pyloric Sphincter: conducts chyme into small intestine
• Rugae: “wrinkles” accounts for distensibility of stomach; allows for expansion

Question 23

Microscopic Anatomy of the Stomach

Answer 23

Mucosa Layer: Gastric pits which open into gastric glands

3 types of secretory cells in gastric glands

1) Mucous neck cells: mucus lining of stomach
2) Parietal (Oxyntic) Cells: hydrochloric acid
3) Chief (Zymogenic) Cells: pepsinogen which is cleaved to form pepsin

Question 24

The Small Intestine

Answer 24

• Time=3-6 hours
• Longest part of alimentary canal
• Site of most enzymatic digestion and almost all absorption of nutrients
• Most digestive enzymes are secreted by pancreas not small intestine
• Churning and peristalsis shuffle chyme to maximize absorption
• Runs from pyloric sphincter to first part of large intestine

Question 25

Small Intestine- Duodenum

Answer 25

-receives digestive enzymes from pancreas and bile duct STRUCTURES: - hepatopancreatic ampulla: bulb that collects secretions from bile/liver and pancreas - major duodenal papilla: entry

Question 26

Jejunum

Answer 26

Empty (40% of SI)-absorption

Question 27

Ileum

Answer 27

Twisted (60% of SI)- absorption

Question 28

Villi

Answer 28

like projections of mucosa specialized for absorption in small intestine

Question 29

Layers of Villi

Answer 29

Absorption cells -Enterocytes: simple columnar epithelial cells -Goblet Cells: secrete mucus to lubricate chime and provides protective surface Lacteal: blood and lymph capillaries Smooth Muscle within villi to move during digestion

Question 30

The Large Intestine

Answer 30

- Time: 12-24 hours - Food breakdown occurs - BreLast major organ of alimentary canal - Little additional akdown that occurs is bacterial - Main function is to absorb water and electrolytes resulting in semi-solid feces - Mass peristaltic movements: slow sluggish and weak movements propel

Question 31

Structures of the Large Intestine

Answer 31

Cecum "blind sac"- beginning of large intestine -ileocecal valve: prevents reflux of feces Verniform appendix "worm-shaped"-blind tube that opens on poster medial wall of cecum -Lymphoid tissue to collect neutralize pathogens -Colon

Question 32

Colon

Answer 32

- Ascending colon - Right colon (hepatic) flexure - Transverse Colon - Left colon (splenic) flexure - Descending colon - Sigmoidal colon (s shaped)

Question 33

structures of the Large Intestine

Answer 33

- rectum | - anal canal

Question 34

Rectum

Answer 34

Straight: joins sigmoid colon; descends and retroperitoneally along inferior portion of sacrum - no tenaie coli; has longitudinal muscle - rectal valves: transverse fold of rectum that prevent feces from being passed with flatus (gas)

Question 35

Anal Canal

Answer 35

Passes through elevator ani muscle and lies external to abdominopelvic cavity 2 SPHINCTERS - External anal Sphincter: will contract voluntarily to inhibit defecation - Internal Anal Sphincter: will contract involuntarily to inhibit infection - Both will prevent fecal leakage from anus between defecations and will exhibit defecation from emotional stress

Question 36

Special Features of Large Intestine

Answer 36

TENIAE COLI: "Colon Ribbons"- thickenings of longitudinal muscle layer to maintain muscle tone HAUSTRA: "draw up"- puckered sacs caused by teenier coli EPIPLOIC (OMENTAL) APPENDAGES: "Membrane covered"- fat filled pouches of visceral peritoneum; unknown functions

Question 37

Gallbladder

Answer 37

- Muscular Sac resting on the visceral surface of right hepatic lobe - Functions to store and concentrate bile - When fatty chyme enters duodenum, a hormone cholecytoskinin is released from enterodendocrine cells of duodenum-cause bile duct sphincters to relax and bile is expelled Cystic Duct

Question 38

Pancreas

Answer 38

- Exocrine and endocrine gland - Produced most of the enzymes that will digest food in the small intestine Structures: - Head - Body - Tail - Main pancreatic duct: drains most of the

Question 39

Acinar (Acini) glands

Answer 39

are responsible for synthesizing, storing, and secreting pancreatic digestive enzymes

Question 40

Acinar (Acini) cells

Answer 40

compose glands

Question 41

Zygomen granules

Answer 41

Enzymes are stored in their inactive form in intracellular granules