digest

Question 1

Introduction: specialized for? consists of? located?

Answer 1

• specialized for digestion and absorption of food
• consists of digestive tract and accessory digestive glands
• located predominantly in the abdominopelvic cavity

Question 2

Introduction: walls/organs lined with? cavity?

Answer 2

• walls of cavity lined with parietal peritoneum
• organs covered with layer of visceral peritoneum
• peritoneal cavity is space between the two layers

Question 3

Functions (6)

Answer 3

• Ingestion: food and liquid taken in
• Secretion: acids, buffers, enzymes
• Motility: mixes and moves food along digestive tract
• Digestion: Mechanical and Chemical
• Absorption: materials move acroos digestive epithelium
• Elimination: waste is compacted and excreted

Question 4

Digestion: chemical vs mechanical?

Answer 4

• mechanical: teeth and tongue break food into smaller particles
• chemical: food broken down by acid and enzymes

Question 5

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Question 6

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Question 7

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Question 8

Tongue - composed of _ muscle? orientation? allows?

Answer 8

• composed of multiple layers of skeletal muscle
• oriented at different angles
• allow movement in multiple directions

Question 9

Tongue - functions? (3)

Answer 9

• positions food within oral cavity
• sensory organ - temperature and taste (sweet, salty, sour, bitter, umami)
• organ of speech

Question 10

Gastrointestinal Tract - oral cavity? pharynx? esophagus?

Answer 10

• OC: teeth, tongue and salivary glands fragment and hydrate food
• P: initiates swallowing
• E: muscular tube that conducts food from pharynx to stomach

Question 11

GI Tract: stomach? small intestine? large?

Answer 11

• S: muscular sac that stores food and initiates digestion
• SI: digestion and absorption
• LI: compaction and storage of feces

Question 12

Teeth - decidous? permanent? replacement? function?

Answer 12

• deciduous aka temporary aka baby dentition: 20 teeth
• permanent dentition: 32 teeth
• replacement occurs between 6 and 17
• function in mechanical breakdown of food aka mastication

Question 13

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Question 14

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Question 15

Esophagus - what? size? where? lined with?

Answer 15

• muscular tube extending from pharynx to stomach
• 25 cm long, 2cm in diameter
• passes along posterior mediastinum through diaphragm, into adominal cavity
• lined with stratified squamous non-keratinized epithelium

Question 16

Muscules of the esophageal wall- upper and lower?

Answer 16

• Upper portion: skeletal aka voluntary
• can decide to continue swallowing or bring food back up
• lower portion: smooth aka involuntary
• committed to finish swallowing

Question 17

Stomach - what? does what? mechanically? chemically? mixes?

Question 18

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Question 19

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Question 20

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Question 21

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Question 22

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Question 23

Gastric Cland Cells (5)

Answer 23

• surface mucus cells
• mucus neck cells
• parietal cells
• chief cells
• enteroendocrine cells

Question 24

Enteroendocrine Cells

Answer 24

• secrete hormones
• G cells secrete gastrin
• gastrin stimulates secretion of parietal and chief cells

Question 25

Gastric Gland Cells - surface mucus and mucus neck?

Answer 25

* SM: secrete alkaline mucus to protect epithelium from acid * mucus neck: secrete protective mucus

Question 26

GG Cells - parietal? chief?

Answer 26

* P: secrete HCl and intrinsic factor (vit B12 absorption) * C: secrete pepsinogen - converted into pepsin by stomach acid

Question 27

Small intestine - 3 regions?

Answer 27

* duodenum * jejenum * ilieum

Question 28

Duodenum - size? shape? recieves?

Answer 28

* short, 25 cm or 10 in * C shaped segment * receives chyme from stomach * receives secretions of pancreas and gall bladder

Question 29

Jejenum - size? function?

Answer 29

* 2.5 m or 8 ft * majority of digestion and absorption

Question 30

Ilieum - size? function?

Answer 30

* final segment, 2.5 m or 12 ft long * digestion and absorption completed * empties into large intestine

Question 31

Neutralization of Chyme

Answer 31

* pH of chyme in stomac is acidic, but digestive enzymes in SI have alkaline pH optimum * chyme is released slowly from the stomach by the pyloric sphincter * as it enters duodenum, rapidly neutralized by: alkaline secretions from pancreas and alkaline mucus secreted by subjucosal glands of the duodenum (Brunner's)

Question 32

Duodenum position

Answer 32

Question 33

Surface Area of Small Intestine

Answer 33

* 6m/20 ft length, 2.5

Question 34

Large Intestine - shape and size? functions?

Answer 34

* horseshoe shaped tube * 1.5 m/ 5 ft long * 7.5 cm / 3 in in diameter * reabsorbs water and electrolytes * absorbs important vitamins produced by colonic bacteria - K and B 12 * compacts and stores feces

Question 35

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Question 36

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Question 37

Duodenum Position

Question 38

Intenstinal Wall - mesentery? plicae circulares? villi?

Question 39

Specializations of Intestinal Wall: d vs. J vs. I

Answer 39

* duodenum: plicae, glands and villi * jejenum: most numerous plicaie and villi * ileum: reduced in height villi, peters patches: permanent lymphoid nodules

Question 40

Digestive Tract Epithelium Comparison