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A&P 2 - Unit 2 > 22-2: Upper GI tract > Flashcards

22-2: Upper GI tract Flashcards

1
Q

oral cavity

A

food enters the GI tract thru the mouth, which is continous with the oropharynx posteriorily. THe boundaries of the mouth are the lips, cheeks, palate, and tongue

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2
Q

palate

A

forms the roof of the mouth and has two distinct parts - the hard palate anteriorly is mucus membrane covering bones (maxilla and palatine bone); the soft palate posteriorly is skeletal muscle covered with mucus membrane. Projecting down in the back is a fingerlike uvula

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3
Q

tongue

A

mucosa covered skeletal muscle, covered with papille, some of which are taste buds. The tongue mixes food with saliva and forms it into a soft compact mass called a bolus for swallowing. The tongue is connected dorsally by the lingual frenulum

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4
Q

What are the classifications of teeth?

A

incisors
canines
premolars
molars

teeth function in mastication

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5
Q

What are the layers of the teeth?

A

enamel covered crown
cementum covered root
bulk of the tooth is dentin, surrounding a central pulp cavity

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6
Q

salivary glands

A

3 pairs of glands that secrete saliva through ducts into the oral cavity

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7
Q

What are the locations of the 3 pairs of salivary glands?

A

parotid - large glands that lie anterior to the ear, between the masseter and skin

submandibular - glands under the jaw at the back of the tongue

sublingual - small glands under the tongue, near the front of the mouth

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8
Q

mumps

A

infection of the parotid glands

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9
Q

What is saliva mostly made of?

A

H2O with dissolved electrolytes

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10
Q

mucin

A

protein that forms thick mucus when dissolved in water, lubricates the food in teh saliva for swallowing

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11
Q

bicarbonate ions in saliva

A

keep salivary pH close to neutral

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12
Q

salivary amylase

A

an enzyme that begins the chemical breakdown of starches in food

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13
Q

lysozyme

A

an enzyme that inhibits bacterial growth in the mouth

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14
Q

salivation is primarily controled by the __ nervous system.

A

parasympathetic division of ANS - small amounts of saliva are continously secreted to keep the mouth moist, but when food enters the mouth, the glands secrete large amounts of saliva

(note, stress causes dry mouth)

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15
Q

In addition to ingestion, when other processes occur in the oral cavity?

A

mastication

chemical digestion

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16
Q

mastication

A

the teeth mechanically break down food and the tongue mixes these pieces with saliva to form a soft mass called a bolus that can be swallowed. this is an example of mechanical digestion

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17
Q

chemical digestion in the oral cavity

A

the enzyme salivary amylase begins the chemical breakdown of starch in the mouth; acts on carbohydrates until it is denatured by acid in the stomach

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18
Q

pharynx

A

Food passes posterily from the mouth into the oropharynx and then into the laryngopharynx. Both are common passageways for food, fluid, and air. The pharynx has skeletal muscle in its walls and is lined with mucus secreting epithelium. Contractions of these muscles push food into the esophagus below.

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19
Q

What organ is part of both the respiratory and digestive system?

A

pharynx

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20
Q

esophagus

A

10” muscular tube lying posterior to the trachea in the neck

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21
Q

esophageal hiatus

A

opening in the diaphragm where the esophagus passes through and enters the abdomen, where it empties into the stomach

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22
Q

hiatal hernia

A

stomach pushes up through esophegeal hiatus into thorax, gastric juice enters esophagus

GERD - gastroesophageal reflux disease (eg. heartburn)

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23
Q

Do the pharynx and/or esophagus produce enzymes or carry out any absorption?

A

no - they secrete mucus and transport food to the stomach. No digestion takes place

24
Q

deglutition

A

swallowing - mechanism that moves food from the mouth to thes tomach

25
Q

What are the two major phases of deglutition?

A

buccal phase - mouth, voluntary

pharyngeal-esophageal phase - pharynx and esophagus, involuntary

26
Q

buccal phase of deglutition

A

occurs in mouth and is volunary

the tip of the tongue presses up against the hard palate and the tongue contracts, pushing the bolus into the oropharynx. Once food enters the pharynx, it passes out of our control and becomes an involuntary reflex

27
Q

pharyngeal-esophageal phase of deglutition

A

controlled by swallowing center in the medulla. As the epiglottis tips over the larynx, keeping food out of the airways, the bolus slides into the esophagus (breathing stops temporarily). The bolus is squeezed down the esophagus to the stomach

28
Q

How does the bolus move down the esophagus?

A

peristalsis (wave like contractions of the muscularis)

29
Q

stomach

A

J shaped enlargement of the GI tract just below the diaphragm; it is a collapsible elastic bag that can store large amounts of food temporarily.

30
Q

rugae

A

when empty, the stomach collapses inward, throwing its mucosa into these large folds

31
Q

What are the four regions of the stomach?

A

cardia
fundus
body
pyloric region

32
Q

cardia

A

where food first enters the stomach from the esophagus

33
Q

fundus

A

dome shaped bulge superior and lateral to the cardia

34
Q

body

A

large central portion of the stomach

35
Q

pyloric region

A

lower region of stomach that connects to small intestine

36
Q

sphincter

A

thick circular band of muscle that acts as a valve between organs by opening (relaxing) or closing (contracting)

37
Q

cardiac sphincter

A

aka gastroesophageal sphincter

valve between esophagus and cardia of the stomach. Normally closed, opens reflexively when a bolus reaches the bottom of the esophagus, then closes to prevent back flow of stomach acid into the esophagus

(if it doesn’t close properly - acid reflux, GERD)

38
Q

pyloric sphincter

A

valve between pylorus of stomach and the duodenum. Opens to allow the passage of a small amount of liquified food from the stomach into the duodenum of the small intestine. Controls stomach emptying

39
Q

gastric juice

A

secretion of the gastric glands into the stomach mucosa

40
Q

mucus

A

goblet cells in the stomach secrete a thick coating of bicarbonate rich mucus to protect the stomach from ‘eating itself’.

41
Q

gastritis

A

inflammation of the stomach wall caused by a breach of the mucus barrier; acute and temporary

42
Q

gastric ulcer (or peptic ulcer)

A

erosion of the stomach wall causing persistant damage to mucus and underlying tissues

43
Q

Helicobacter pylori

A

this bacterium is the direct cause of 90% of gastric ulcers,

44
Q

Hydrochloric acid

A

strong acid secreted by the parietal cells in the stomach. Creates an acidic pH in the stomach that kills most microbes and activates pepsinogen

45
Q

pepsinogen

A

inactive enzyme produced by the chief cells in the stomach. HCl converts it to the active enzyme pepsin, which begins the chemical breakdown of proteins

46
Q

intrinsic factor

A

glycoprotein from parietal cells that is required for intestinal absorption of vitamin B12, which is needed to produce mature red blood cells

47
Q

What do the parietal cells produce?

A

HCl, intrinsic factor

48
Q

What do the chief cells produce?

A

pepsinogen

49
Q

chyme

A

paste in the stomach created by mixing waves combining food with gastric juices; temporarily stored in the stomach and released in small amounts into the duodenum

50
Q

What enzymes engage in chemical digestion in the stomach?

A

pepsin - breakdown of proteins
rennin - digestion of milk in children

only 2 enzymes that can work at the low pH of stomach

51
Q

Is anything absorbed in the stomach?

A

food substances are not absorbed until they reach the small intestine, but alcohol, asprin, and some other drugs pass easily into the blood

52
Q

What is the neural regulation of gastric secretion?

A

parasympathetic nerve impulses from the vagus nerve stimulate the gastric glands to secrete gastric juice. Stimuli include the small, sight, taste, and thought of food, or the stretch of the stomach walls

53
Q

Strong emotions may ___ gastric secretions (why?)

A

inhibit/slow down, because stress activates the sympathetic nervous system

54
Q

What hormone regulates gastric secretion?

A

gastrin - a local hormone produced by the gastric glands in response to the presence of certain foods in the stomach, stimulates the release of gastric juice

55
Q

gastric emptying

A

pyloric sphincter just barely opens when paristaltic wave reaches pylorus. A small amount of chyme is released to the duodenum, then the valve closes and the remaining chyme shoots back up into the stomach for further mixing

56
Q

The upper GI tract runs between what organs?

A

mouth to pyloric sphincter - the 3 accessory glands are at the junction

lower GI tract runs from duodenum to anus

A&P 2 - Unit 2 (11 decks)

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