Chapter 23 The Digestive System

Question 1

Function of digestive system

Answer 1

• Food intake
• Digestion of food into nutrient molecules
• Absorption of nutrient into blood
• Elimination of waste

Question 2

Alimentary Canal + Accessory Organs

Answer 2

Mouth, tongue, salivary glands (parotid gland, sublingual gland, submandibular gland), pharynx, stomach, pancreas, liver, gallbladder, duodenum, jejunum, ileum, large intestine stuff….

Question 3

Divisions of Digestive system

Answer 3

• Alimentary canal- gastrointestinal tract, from mouth to anus, contents outside of body
• Accessory digestive organs- physical breakdown and propulsion of foodstuffs: teeth and tongue; chemical breakdown of foodstuffs: gallbladder, salivary glands, liver, pancreas

Question 4

Abdominal quadrants

Answer 4

4 quadrants R/L Upper/Lower

Question 5

Abdominal Regions

Answer 5

Right Hypochondriac| Epigastric | Left Hypochond
Right Lumbar | Umbilical | Left Lumbar
Right iliac (inguinal) | Hypogastric| Left iliac (inguin)

Question 6

4 layers of alimentary canal wall

Answer 6

External to internal:

serosa, muscularis externa, submucosa, mucosa

Question 7

Mucosa

Answer 7

Innermost layer- lines lumen
3 layers:
- epithelium - continuous with ducts that dump into lumen
- Lamina propria (CT)- vasculature for absorption
- Muscularis mucosae (smooth muscle)- local movement of mucosa

Question 8

Submucosa

Answer 8

• CT- rich in elastic fibers

- blood vessels, lymphatic vessels, nerves

Question 9

Muscularis Externa

Answer 9

• 2 layers of smooth muscle: circular layer, longitudinal layer (sometimes circular layer thickens in areas to become sphincter)

Question 10

Serosa

Answer 10

• visceral peritoneum

- simple squamous epithelium (mesothelium)

Question 11

Smooth muscle tissue

Answer 11

6 major locations:

• iris of eye
• walls of blood vessels
• respiratory tubes
• digestive tubes (muscularis mucosae, muscularis externa)
• urinary organs
• reproductive organs

Question 12

Smooth muscle anatomy

Answer 12

Irregularly arranged thick and thin filaments thus no striations

• intermediate filaments of the cytoskeleton attach to dense bodies (similar to z-discs)
• contraction occurs in a corkscrew fashion, pulling dense bodies closer together

Question 13

Peritoneum

Answer 13

serous membrane of the abdominopelvic cavity

Question 14

Mesentery

Answer 14

double layer of peritonem

• holds organs in place
• stores adipose
• route for vessels to/from the organs

Question 15

Dorsal mesentery

Answer 15

extends dorsally from the alimentary canal to the posterior abdominal wall

• Greater omentum - greater curvature of stomach, around transverse colon to posterior wall of abdomen
• contains fat
• mesentery- long coils of jejunum and ileum supported
• transverse mesocolon- holds transverse colon to posterior abdominal wall (almost horizontal)
• sigmoid mesocolon- connects sigmoid colon to posterior pelvic wall

Question 16

Ventral mesentery

Answer 16

extends ventrally from the stomach and liver to anterior abdominal wall

• falciform ligament - binds anterior aspect of liver to anterior abdominal wall/diaphragm
• lesser omentum runs from the liver to the lesser curvature of the stomach and beginning of duodenum

Question 17

Retroperitoneal organs of GI tract

Answer 17

lack peritoneum…fuse to the dorsal abdominal wall

- duodenum, ascending colon, descending colon, rectum, pancreas

Question 18

Intraperitoneal Organs and their mesenteries

Answer 18

Liver (falciform, lesser omentum)
Stomach (greater and lesser omentum)
ileum/jejunum (mesentery)
transverse colon (transverse mesocolon)
sigmoid colon (sigmoid mesocolon)

Question 19

Mouth and associated organs

Answer 19

oral cavity

• mucosa-lined cavity
• very thick stratified squamous epithelium

Question 20

Tongue

Answer 20

• Internal muscles change shape of the tongue; not attached to any bones
• External muscles change the position of the tongue; attached to bones of the skull and hyoid

Question 21

Surface anatomy of the tongue

Answer 21

posterior 1/3- lingual tonsil- oropharynx, sulcus terminalis
Anterior 2/3- circumvallate papillae, fungiform papillae (reddish), filiform papillae (most abundant, roughened, white appearance)

Question 22

Salivary glands

Answer 22

Parotid- big, backwards
Sublingual- under tongue
Submandibular- below mandible, back (duct more anterior than sublingual ducts)

Saliva cleanses teeth and dissolves food; body makes 2-4 pints a day?

Question 23

Pharynx is part of both_______ systems.

Answer 23

Respiratory/digestive

Question 24

Esophagus

Answer 24

• collapsible muscular tube
• laryngopharynx -> stomach

Muscularis externa:
top 1/3 -skeletal muscle
mid 1/3- skeletal and smooth
end 1/3- smooth muscle

Question 25

Microscopic anatomy of esophagus

Answer 25

Mucosa (stratified squamous epithelium), submucosa, then muscularis externa ( 2 layers circular, longitudinal)

Question 26

Stomach

Answer 26

- widest part of ealimentary canal - food temporarily stored (4 hours) and made into chyme - first site of chemical breakdown (pepsin)

Question 27

Gross anatomy of stomach

Answer 27

Hard to explain, know it...

Question 28

Chief cell secretes?

Answer 28

pepsinogen

Question 29

Parietal cell secretes?

Answer 29

HCl

Question 30

Small intestine

Answer 30

longest part of alimentary canal - site of most enzymatic digestion and almost all absorption of nutrients - segmentation- moves chyme all around increasing contact with absorptive mucosal lining - peristalsis- propels chyme through SI

Question 31

Gross anatomy of SI

Answer 31

duodenum- c shaped (12 finger widths long) Jejunum- Upper, 40% of small intestine Ileum- (longest part) Lower, 60% of small intestine

Question 32

Pilcae circularis?

Answer 32

permanent, transverse circular folds of the mucosa and submucosa which aid in segmentation and increase surface area for absorption: 1 tall

Question 33

Villi?

Answer 33

Finger-like projections in the mucosa which are ~1mm tall and viewable with eye - Enterocytes/absorptive cells- simple columnar epithelium specialized for absorbing digested nutrients

Question 34

Microvilli?

Answer 34

Tiny, finger-like projections on apical side of each simple columnar epithelial enterocytes of the villi

Question 35

Large intestine

Answer 35

- receives undigested food from small intestine - absorbs water and electrolytes - pass feces out of gi tract - mass peristaltic movements vs. constant peristalsis

Question 36

Teniae Coli?

Answer 36

3-longitudinal strips running the length of the LI | - thickenings of the longitudinal layer of the muscularis externa

Question 37

Haustra?

Answer 37

sac-like bulges formed by the muscle tone of the large intestine

Question 38

Epiploic appendages?

Answer 38

fat- filled pouches of visceral peritoneum that hang from the intestine - unknown significance/function

Question 39

Anal sphincter anatomy

Answer 39

Levator ani muscle, external anal sphincter, internal anal sphincter, anus

Question 40

Defecation

Answer 40

Stretch of rectal wall due to feces-> cerebral cortex (conscious control)-> voluntary motor nerve to external anal sphincter-> inhibition of voluntary motor neurons allowing external anal sphincter to relax so feces may pass

Question 41

Goblet cells of LI

Answer 41

need lots of goblet cells because of mass movements of solids? More goblet cells found proximally near the ileum

Question 42

Liver

Answer 42

- largest gland in the body | - bile production- green liquid (alkaline) stored in the gallbladder

Question 43

Gallbladder

Answer 43

- muscular sac on the underside of right lobe of liver | - stores and concentrates bile

Question 44

Know ducts that transport bile

Answer 44

- right/left hepatic duct, common hepatic duct (joins with cystic duct from gallbladder) to exit to the duodenum by the common bile duct

Question 45

Pancreas

Answer 45

- exocrine function= enzymes for digestion in small intestine - endocrine function = hormones for glucose regulation