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Anatomy and Physiology: 2 > digestive system > Flashcards

digestive system Flashcards

1
Q

what is gastroenterology?

A

the study of the digestive tract and the diagnosis and treatment of its disorders

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2
Q

what is the digestive system?

A

an organ system that processes food, extracts nutrients, and eliminates residue

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3
Q

what are the 5 stages of digestion/

A
  1. ingestion: selective intake of food
  2. digestion: mechanical and chemical breakdown of food into a form usable by the food
  3. absorption: uptake of nutrient molecules into the epithelial cells of the digestive tract and then into the blood and lymph
  4. compaction: absorbing water and consolidating the indigestible residue into feces
  5. defecation: elimination of feces
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4
Q

what is mechanical digestion?

A

physical breakdown of the food into smaller particles

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5
Q

what is chemical digestion?

A

series of hydrolysis reactions that break dietary macromolecules (polymers) into their monomers (residues)

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6
Q

what is the digestive tract?

A
  • 30 ft long muscular tube extending from the mouth to the anus
  • mouth, pharynx, esophagus, stomach, small intestine, and large intestine
  • The gastrointestinal tract is the stomach and intestines
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7
Q

what are the Accessory organs?

A
  • teeth, tongue, salivary glands, liver, gallbladder, and pancreas
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8
Q

what are the layers of the digestive tract?

A
  1. Mucosa: epithelium (simple columnar), lamina propria (loose connective tissue), muscularis mucosae (thin layer of smooth muscle) MALT
  2. submucosa (loose connective tissue)
  3. Muscularis externa: inner circular layer (contains sphincters), outer longitudinal layer (motility that propels food and residue)
  4. Serosa: areolar tissue, mesothelium (areolar tissue w/simple squamous mesothelium) - reduces friction
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9
Q

what is adventitia?

A

fibrous connective tissue layer that binds and blends the pharynx, most of the esophagus, and the rectum into adjacent connective tissue of other organs

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10
Q

what is the Enteric Nervous system?

A

nervous network in the esophagus, stomach, and intestines that regulates digestive tract motility, secretion, and blood flow

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11
Q

what two networks of neurons make up the enteric nervous system?

A
  • Submucosal plexus: in the submucosa (controls glandular secretions of the mucosa, controls movements of muscularis mucosae)
  • Myenteric plexus: parasympathetic ganglia and nerve fibers between the two layers of the muscularis external (control peristalsis)
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12
Q

what is a mesenteries?

A

connective tissue sheets that suspend the stomach and intestines from the abdominal wall

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13
Q

what is parietal peritoneum?

A

a serous membrane that lines the wall of the abdominal cavity

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14
Q

what is the lesser omentum?

A

a ventral mesentery that extends from the lesser curvature of the stomach to the liver

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15
Q

what is the greater omentum?

A

hangs from the greater curvature of the stomach and covers the small intestine and apron

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16
Q

what is the mesocolon?

A

an extension of the mesentery that anchors the colon to the abdominal wall

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17
Q

what is intraperitoneal?

A

when an organ is enclosed by the mesentery on both sides
- considered within the peritoneal cavity
- stomach, liver, and parts of small and large intestine

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18
Q

what is retroperitoneal?

A

when an organ lies against the posterior body wall and is covered by peritoneum on its anterior side only
- considered to be outside the peritoneal cavity
- duodenum, pancreas, and parts of the large intestine

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19
Q

what are motility and secretion of the digestive tract controlled by?

A
  • Neural control: short (myenteric) reflexes: stretch or chemical stimulation acts through myenteric plexus
  • Hormones: chemical messengers secreted into bloodstream
  • paracrine secretions: chemical messengers that diffuse through the tissue fluids to nearby target cells
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20
Q

what is long (vagovagal) reflexes?

A

parasympathetic stimulation fo digestive motility and secretion

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21
Q

what is peristalsis?

A

adjacent segment of alimentary tract organs alternately contract and relax, which moves food along the tract distally

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22
Q

what is segmentation?

A

nonadjacent segments of alimentary tract organs alternately contract and relax, moving the food forward then backward

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23
Q

what tissue type lines the mouth?

A

stratifies squamous epithelium
- keratinized in gums and hard palate
- nonkeratinized in floor of mouth, soft palate and cheeks

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24
Q

what is the tongue? main function?

A

muscular bulky but agile and sensitive organ
- manipulate, sense food, taste/texture

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24
Q

what tissue type makes up the tongue?

A

nonkeratinized stratified squamous

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25
Q

what is the hard palate?

A

anterior portion that is supported by the palatine processes of the maxillae and the palatine bone

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26
Q

what are the parts of the tongue?

A
  • lingual papillae: bumps that are taste buds
  • body: anterior 2/3
  • root: posterior 1/3
  • lingual frenulum: attaches body of tongue to floor of mouth
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27
Q

what is the uvula?

A

conical medial projection visible at the rear of the mouth

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27
Q

what is the palate?

A

separates oral cavity from nasal cavity

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28
Q

what is the soft palate?

A
  • posterior with a more spongy texture
  • skeletal muscle and glandular tissue
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29
Q

what does it mean to masticate?

A

chew; makes it easier to swallow food

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30
Q

how many of each teeth do we have?

A
  • 32 total
  • 2 incisors
  • 1 canine
  • 2 premolars
  • 3 molars
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31
Q

what are the regions of the tooth?

A
  • crown: above gum
  • root: below gum in bone
  • nech: where crown, root and gum meet
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32
Q

what are the layers of the tooth?

A
  • dentin: hard yellowish tissue (regenerates)
  • enamel: covers crown and neck (no regenerate)
  • cementum: cover root (no regenerate)
  • root canal: space in a root leading to pulp cavity in the crown
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33
Q

what is salivary amylase?

A

enzyme that begins starch digestion

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34
Q

what is saliva made of?

A

hypotonic sol: 99% water
- phosphate and bicarbonnates
- ph: 6.8 - 7
moistens mouth and dissolves molecules

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35
Q

what is lingual lipase?

A

enzyme that is activated by stomach acid and digests fat after food is swallowed

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36
Q

what is salivation activated by?

A

medulla oblongata and pons respond to signals generated by the presence of food
- parasympathetic: stimulate the glands to produce an abundance of thin, enzyme-rich saliva
- sympathetic: inhibits the glands, thus producing less and thicker, saliva with more mucus

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37
Q

what is a bolus?

A

ass swallowed as a result of saliva behind food particles into a soft, slippery, easily swallowed mass

38
Q

what does the pharynx do?

A

connects the oral cavity to the esophagus and the nasal cavity to the larynx
- forms pharyngeal constrictors

39
Q

what does the esophagus do?

A

contains lower esophageal sphincter: food pauses here because of constriction
- prevents stomach contents from regurgitating into the esophagus
- nonkeratinized stratified squamous

40
Q

what is the action of swallowing?

A

deglutition: a complex action involving over 22 muscles in the mouth, pharynx, and esophagus
- swallowing center: medulla oblongata

41
Q

what are the three phases of swallowing

A
  1. oral: the tongue forms and food bolus and pushes to laryngopharynx (vol)
  2. pharyngeal: palate, tongue, vocal cords and nasal cavities and airway while pharyngeal constrictors push the bolus into esophagus (invol)
  3. esophageal: peristalsis drives the bold downward and relaxation of the lower esophageal sphincter admits it into the stomach
42
Q

what does the stomach do?

A

mechanically breaks up food, liquifies it and begins chemical digestion of protein and fat

42
Q

what is chyme?

A

soupy or pasty mixture of semi-digested food in the stomach

42
Q

where does the stomach receive its info from?

A
  • parasympathetic fiber from vagus nerve
  • sympathetic fibers from celiac ganglia (solar plexus
43
Q

what are the 4 regions of the stomach?

A
  1. cardial
  2. fondus
  3. body
  4. pyloric part
44
Q

what are the muscular layers of the stomach?

A
  • longitudinal
  • circular
  • oblique
44
Q

what is gastric juice?

A

mixture of water, hydrochloric acid and pepsin

45
Q

what cells are in the stomach mucosa?

A
  • mucous cells: secrete mucus
  • regenerative cells: base of pit, replace old with new
  • parietal cells: upper half, secrete HCl, intrinsic factor and secrete ghrelin
  • chief cells: secrete gastric lipase and pepsinogen
  • enteroendocrine cells: secrete hormone and paracrine messengers
46
Q

what does HCl do in the stomach?

A
  • activates pepsin and lingual lipase
  • breaks up connective tissues and plant cell walls
  • destroys most ingested pathogens
47
Q

what is a peptic ulcer?

A
  • acid-resistant bacteria Helicobacter pylori, which can be treated with antibiotics and Pepto-Bismol
  • pepsin and hydrochloric acid erode the stomach wall.
47
Q

what does gastic lipase do?

A
  • produced by chief cells
  • digest dietary fats
47
Q

what does intrinsic factor do?

A
  • secreted by parietal cells
  • essential to absorb vitamin B
47
Q

what are the 2 main functions of the contraction of gastric smooth muscle?

A
  1. ingested food is crushed, ground, and mixed, liquefying it to form what is called chyme.
  2. chyme is forced through the pyloric canal into the small intestine, a process called gastric emptying
48
Q

when do digestion and absorption occur?

A

after chyme has passed into the small intestine

48
Q

what are the protective mechanisms in the stomach?

A
  1. mucus coat: thick, highly alkaline mucus resists the action of acid and enzymes
  2. tight junction: prevent gastric juice from seeping between them and digesting deeper tissue
  3. epithelial cell replacement: cells live only 3-6 days, replaced by cell division
49
Q

what are the 3 phases of gastric activity?

A
  1. Cephalic phase: stomach being controlled by the brain
  2. Gastric phase: stomach controlling itself
  3. Intestinal phase: stomach being controlled by small intestine
50
Q

What does the small intestine recieve?

A

chyme from stomach
secretions from liver and pancreas

51
Q

anatomy of the liver?

A

reddish brown gland located immediately inferior to the diaphragm
- largest gland
- produces and secretes bils

52
Q

what are hepatocytes?

A

they absorb things from the blood
- glucose, amino acids, iron, vitamins
they break down stored glycogen and release it to the blood

53
Q

what do Hepatocytes remove and degrade?

A

hormones, toxins, bile pigments, and drugs

54
Q

what do the hepatocytes secrete into the blood?

A

albumins, lipoproteins, clotting factors, angiotensinogen

55
Q

what does the gallbladder do?

A

serves to store and concentrate bile by absorbing water and electrolytes

56
Q

what is bile?

A

yellow-green fluid containing minerals, cholesterol, neutral fats, phospholipids, bile pigments, and bile acids (steroids from cholesterol)

57
Q

what is the pancreas?

A

Is spongy retroperitoneal gland posterior to the greater curvature of stomach

58
Q

what is the portion of the pancreas?

A
  • endocrine: pancreatic islets that secrete insulin and glucagon
  • exocrine: acini cells: 99% of the pancreas that secretes 1,200 to 1,500ml of pancreatic juice per day
59
Q

what is pancreatic juice?

A

alkaline mixture of water, enzymes, zymogens, sodium bicarbonate, and other electrolytes

60
Q

what are pancreatic zymogens?

A
  • trypsinogen
  • chymotrypsinogen
  • procarboxypeptidase
61
Q

what stimuli are responsible for regulating secretion?

A
  1. Ach: stimulates the pancreas to secrete enzymes during the cephalic phase of gastric control
  2. CCK: secreted by the mucosa of the duodenum in response to the arrival of fats in the small intestine
  3. Secretin: released from duodenum in response to acidic chyme arriving from the stomach
62
Q

What occurs in the small intestine?

A

nearly all chemical digestion and nutrient absorption
- coiled mass filling most of the abdominal cavity inferior to the stomach and liver

62
Q

what are the 3 regions of the small intestine?

A
  • Duodenum: receives stomach contents, stomach acid is neutralized here, fats are broken, pepsin inactivated
  • Jejunum: most digestion and nutrient absorption
  • ileum: MALTs present, ileocecal junction and ileocecal valve
63
Q

what tissue type is the lumen lined with?

A

simple columnar epithelium

63
Q

what are circular folds?

A

promotes more thorough mixing and nutrient absorption
- only involve mucose and submucosa
- they increase surface area by a factor of 2 to 3

64
Q

what is villi?

A

finger-like projections w/absorptive cells and goblet cells
-they increase surface area by a factor of 10

65
Q

what is microvilli?

A

form a fuzzy brush border on the apical surface of each absorptive cell
-increase the surface area by a factor of 20

66
Q

what are brush border enzymes?

A

contained in the plasma membrane of microvilli
- carry out final stages of enzymatic digestion

67
Q

what are the 3 functions of contractions of the small intestine?

A
  1. To mix chyme with intestinal juice, bile, & pancreatic juice
    – To neutralize acid
    – Digest nutrients more effectively
  2. To churn chyme and bring it in contact with the mucosa
    for contact digestion and nutrient absorption
  3. To move residue toward large intestine
68
Q

what is lactose intolerance?

A

when lactose passes undigested into large intestine
- increases osmolarity of intestinal contents
- causes water retention in the colon and diarrhea

69
Q

what are lipases?

A

fat digestion enzymes

70
Q

what are the fat-soluble vitamins?

A

A,D,E, and K

71
Q

What are the water-soluble vitamins?

A

vitamin B complex and C

72
Q

What do minerals do in digestion?

A
  • they are absorbed all along the small intestine
  • exchanged for bicarbonates reversing the chloride-bicarbonate exchange that occurs in the stomach
  • iron absorbed by active transport
73
Q

what does water do in the digestive system?

A

receives about 9L of water a day

74
Q

what does the ascending colon do?

A

right colic (hepatic) flexure

74
Q

what does the appendix do?

A

it attaches to lower end of cecum
- densely populated with lymphocytes

74
Q

what does the descending colon do?

A

frame the small intestine

75
Q

what does the transverse colon do?

A

left colic (splenic) flexure

76
Q

what is the sigmoid colon?

A

is S-shaped portion leading down into pelvic cavity

76
Q

what is the rectum?

A

portion ending at anal canal

77
Q

What are the muscularis externa of the colon?

A
  • Taenia coli: longitudinal fibers concentrated in 3 thickened, ribbon-like strips
  • Haustra: pouches in the colon caused by the muscle tone of the Taeniae coli
  • internal anal sphincter: smooth muscle of muscularis external
  • external anal sphincter: skeletal muscle of the pelvic diaphragm
78
Q

where is mucosa located?

A

anal canal has nonkeratinized stratified squamous epithelium in its lower half for abrasion resistance
- simple columnar epithelium

79
Q

what are intestinal crypts?

A

glands sunken deeps into lamina propria with a high density of mucus-secreting goblet cells

80
Q

what are Haustral contractions?

A

distension of a haustrum stimulates it to contract
- occur every 30 minutes

81
Q

what are mass movements?

A

stronger contractions that occur one to three times a day
- triggered by gastrocolic and duodenocolic reflexes

82
Q

what is a gut microbiome?

A

bacteria digest cellulose, pectin, and other carbohydrates for which our cells lack enzymes
- help in the synthesis of vitamins B and K

83
Q

what is a Flatus?

A

intestinal gas

Anatomy and Physiology: 2 (6 decks)

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