Digestion I Study Guide

Question 1

sequence for the movement of food through the gastrointestinal tract

Answer 1

Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus

Question 2

accessory organs

Answer 2

teeth, tongue, gallbladder, digestive glands

Question 3

glands

Answer 3

salivary glands, liver, pancreas

Question 4

Peristalsis

Answer 4

takes place during propulsion (moving food through GI tract), rhythmic waves of smooth muscle contraction – propels food through the GI tract

Question 5

Segmentation

Answer 5

takes place during mechanical breakdown (chewing, mixing food with saliva, churning food), local contractions of the SI to mix food with digestive juices

Question 6

digestion

Answer 6

series of catabolic steps in which enzymes break complex food molecules into their chemical building blocks

Question 7

Absorption

Answer 7

passage of digested fragments from the lumen of the GI tract into blood/lymph

Question 8

Peritoneum

Answer 8

robust serous membranes of the abdominopelvic cavity
- Visceral peritoneum: membrane on the external surface of most digestive organs
- Parietal peritoneum: membrane on the wall of the abdominal cavity

Question 9

Peritoneal cavity

Answer 9

• Fluid filled space between the two peritoneum
• Fluid lubricates the mobile organs

Question 10

Mesentery

Answer 10

a double layer of peritoneum – extends to the digestive organs from the abdominal walls
- Provides routes for blood vessels, lymphatics, and nerves
- Holds organs in place and stores fat

Question 11

retroperitoneal organ

Answer 11

Organs located outside – posterior to – the peritoneum

Question 12

layers/tunics of GI tract from most internal to external

Answer 12

Mucosa, submucosa, muscularis externa, serosa

Question 13

Submucosa

Answer 13

consists of areolar connective tissue, contains blood and lymphatic vessels, lymphoid follicles and a nerve plexus. Has an abundant number of elastic fibers to help organs regain their shape after storing a large meal

Question 14

Serosa

Answer 14

• Outermost, superficial layer
• Same as the visceral peritoneum
• Formed from areolar connective tissue covered with mesothelium – a single layer of squamous epithelium
• Replaced by fibrous adventitia in the esophagus
• Retroperitoneal organs have BOTH an adventitia and a serosa

Question 15

Muscularis externa

Answer 15

• Muscle layer responsible for segmentation and peristalsis
• Contains an inner, circular muscle layer and an outer, longitudinal muscle layer
• The circular layer occasionally thickens to form sphincters
• Sphincters: act as valves to prevent backflow and control the passage of food

Question 16

Mucosa

Answer 16

tunic layer that lines the lumen, a moist epithelial membrane
Functions:
- Secretes mucus, digestive enzymes, hormones
- Absorbs the end products of digestion
- Protects against infectious disease

Question 17

3 sublayers of mucosa

Answer 17

epithelium, lamina propria, muscularis mucosae

Question 18

Epithelium

Answer 18

most often a simple, columnar epithelium rich in mucus secreting cells
- The mouth, esophagus, anus are stratified, squamous
- Protects digestive organs from enzymes, eases food passage
- May create and secrete its own enzymes and hormones

Question 19

Lamina Propria

Answer 19

loose, areolar connective tissue
- Contains lymphoid follicles to defend against microbes
- Rich supply of capillaries for nourishment and absorption

Question 20

Muscularis Mucosae

Answer 20

very thin layer of smooth muscle

Question 21

simple epithelium of GI tract

Answer 21

Stomach and intestines have simple columnar epithelium

Question 22

stratified epithelium in the GI tract

Answer 22

The mouth, esophagus, anus are stratified, squamous

Question 23

How many layers of muscularis exist in the stomach? How is this different from the rest of the GI tract?

Answer 23

3 – Most of the body has 2

Question 24

Sphincter

Answer 24

act as valves to prevent backflow and control the passage of food (muscularis externa)

Question 25

Is blood entering hepatic circulation rich or poor in Oxygen? How about nutrients?

Answer 25

- Collects nutrient-rich venous blood draining from the digestive viscera and brings it to the liver - Enters oxygenated, leaves deoxygenated?

Question 26

branch of the ANS that stimulates digestive activity

Answer 26

Parasympathetic nervous system

Question 27

The GI tract’s own nervous system is called the

Answer 27

enteric nervous system

Question 28

saliva

Answer 28

mostly water, and slightly acidic. It contains electrolytes, salivary amylase, mucin, lysozyme, urea, igA antibodies, and defensins

Question 29

Major extrinsic salivary glands

Answer 29

produce most of the saliva, located outside oral cavity - parotid, submandibular, sublingual

Question 30

Parotid gland

Answer 30

anterior to the ear. External to the masseter; parotid duct to the oral vestibule

Question 31

Submandibular gland

Answer 31

medial to the body of the mandible, duct to the base of lingual frenulum

Question 32

Sublingual gland

Answer 32

anterior to the submandibular, opens to the floor of the mouth via 10-12 ducts

Question 33

How many permanent, mature teeth are there?

Answer 33

32

Question 34

Incisors

Answer 34

chisel shaped for cutting 8

Question 35

Canines

Answer 35

fang-like for tearing, piercing 4

Question 36

Premolars

Answer 36

broad crowns with rounded cusps, used to grind/crush 8

Question 37

molars

Answer 37

broad crowns with rounded cusps, best for grinding 12

Question 38

Wisdom teeth

Answer 38

3rd molars, emerge around 17-25 years of age 4

Question 39

Where esophagus pierces through the diaphragm

Answer 39

Esophageal hiatus

Question 40

sphincter on the proximal end of the stomach

Answer 40

gastroesophageal /cardiac sphincter (surrounds cardial orifice) - Orifice is closed when food is not being swallowed - Mucus cells on both sides of the sphincter help protect the esophagus from acid reflux

Question 41

Heartburn

Answer 41

- Burning, radiating, substernal pain; mimics MI pain - Cause: regurgitation of stomach acid into the esophagus - First symptom of Gastroesophageal Reflux Disease (GERD) - Increased risk with excessive intake of food/drink, obesity, pregnancy, running - Frequent episodes -> esophagitis, esophageal ulcers

Question 42

Hiatal hernia

Answer 42

- Structural abnormality caused by abnormal weakening of the gastroesophageal sphincter - Superior portion of the stomach protrudes above the diaphragm

Question 43

two phases of deglutination (swallowing)

Answer 43

buccal phase and pharyngeal-esophageal phase

Question 44

Buccal phase

Answer 44

voluntary contraction of the tongue

Question 45

pharyngeal-esophageal phase

Answer 45

involuntary phase driven by the vagus nerve; controlled in the swallowing centers of the medulla and lower pons, respiration is momentarily inhibited, and all undesired routes are blockers