Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Western Medicine 502 > Facets of Digestion > Flashcards

Facets of Digestion Flashcards

1
Q

mechanical digestion

A

the physical breakdown of food into smaller particles

  • cutting and grinding action of the teeth
  • churning action of stomach and small intestines
  • exposes more food surface to the action of digestive enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Chemical digestion

A

a series of hydrolysis reactions that breaks dietary macromolecules into their monomers (residues)
-carried out by digestive enzymes produced by salivary glands, stomach, pancreas and small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the chemical results of chemical digestion?

A

polysaccharides into monosaccharides
proteins into amino acids
fats into monoglycerides and fatty acids
nucleic acids into nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

absorption

A

the uptake of substances into or across tissues

example: once food is digested (broken down to its simplest form) it is able to be absorbed by the small intestine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the two anatomical subdivisions of the digestive system?

A

digestive tract (alimentary canal) and accessory organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

digestive tract (alimentary canal)

A
  • 30 foot long muscular tube extending from mouth to anus
  • mouth, pharynx, esophagus, stomach, small intestine, and large intestine
  • gastrointestinal (GI) tract is the stomach and intestines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

accessory organs

A

teeth, tongue, salivary glands, liver, gallbladder, and pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

key features of GI tract

A
  • smooth muscle within the ‘muscularis externa’ that are responsible for perstalis
  • enteric NS: note submucosal (Meissner) plexus and myenteric (Auerbach) plexus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

peristalsis

A

involuntary rhythmic contractions that move food (pre-stomach) and chyme (post-stomach) through GI tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

enteric nervous system

A

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

  • functions completely independently of the central nervous system
  • ANS exerts a significant influence on its action
  • nerves innervating the esophagus, stomach and intestine are known as the “Auerbach” plexus” (connected to the medulla oblongata)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

motility and secretion of the digestive tract are control by?

A

neural, hormonal, and paracrine mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

neural control: short and long reflexes

A

short (myentreic) reflexes: stretch or chemical stimulation acts through myentric plexus
-long (vagovagal) reflexes: parasympathetic stimulation of digestive motility and secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

hormones

A
  • chemical messengers secreted into bloodstream, and stimulate distant parts of the digestive tract
  • gastrin and secretin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

paracrine secretions (prostaglandins with local effect)

A

-chemical messengers that diffuse through the tissue fluids to stimulate nearby target cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

mastication

A

(chewing): breaks food into smaller pieces to be swallowed and exposes more surface to the action of digestive enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Saliva is made up of?

A

salivary amylase, lingual lipase, mucus, lysozyme, immunoglobulin A, and electrolytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

salivary amylase

A

enzyme that begins starch digestion in the mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

lingual lipase

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

mucus

A

binds and lubricates the mass of food and aids in swallowing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

lysozyme

A

enzyme that kills bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

immunoglobulin A

A

an antibody that inhibits bacterial growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are the five electrolytes in saliva?

A

Na+, K+, CI-, phosphate, and bicarbonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

pharynx

A

a muscular funnel that connects oral cavity to esophagus and allows entrance of air from nasal cavity to larynx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

esophagus

A

a straight muscular tube 25-30 cm long

  • begins at level between C6 and the cricoid cartilage
  • extends from pharynx to cardiac orifice of stomach passing through esophageal hiatus in diaphragm
  • lower esophageal sphincter: food pauses at this point because of this
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

stomach

A

a muscular sac in upper left abdominal cavity immediately inferior to the diaphragm.

  • mechanically breaks up food particles, liquefies the food, and begins chemical digestion of protein and fat
  • most digestion occurs after the chyme passes on to the small intestine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

chyme

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what are the four subregions on the stomach?

A

cardiac region (cardia), fundic region (fundus), body (corpus), and pyloric region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

cardiac region (cardia)

A

small area within about 3 cm of the cardiac orifice

29
Q

fundic region (fundus)

A

dome-shaped portion superior to esophageal attachment

30
Q

body (corpus)

A

makes up the greatest part of the stomach

31
Q

pyloric region

A

narrower pouch at the inferior end
-subdivided into the funnel-like antrum and narrower pyloric canal that terminates at pylorus (narrow passage to duodenum)

32
Q

pyloric (gastroduodenal) sphincter

A

regulates the passage of chyme into the duodenum

33
Q

What is the Vasovagal Reflex?

Explain the Hepatic Portal Circulation.

A

-stomach receives:
parasympathetic fibers from vagus, sympathetic fibers from celiac ganglia,
which are collectively called “vasovagal reflex”

-all blood drained from stomach and intestines enters hepatic portal circulation and is filtered through liver before returning to heart

34
Q

what are the cells of gastric glands?

A

mucous cells, parietal cells, chief cells, and enteroendocrine

35
Q

mucous cells

A

secrete mucus. predominate in cardiac and pyloric glands

36
Q

parietal cells

A

found mostly in the upper half of the gland. secretes 3 things: hydrochloric acid (HCI), intrinsic factor, and a hunger hormone called ghrelin

37
Q

chief cells

A

most numerous. secrete gastric lipase and pepsinogen. dominate lower half of gastric glands. absent in pyloric and cardiac glands.

38
Q

enteroendocrine cells

A

concentrated in lower end of gland. secrete hormones and paracrine messengers that regulate digestion.

39
Q

how is pepsinogen activated to pepsin?

A

hydrochloric acid (HCI) converts pepsinogen to pepsin which breaks down proteins to peptides. protein digestion begins in the stomach.

40
Q

intrinsic factor

A

a glycoprotein secreted by parietal cells.

  • essential to absorption of vitamin B12 by the small intestine: binds vitamin B12 and intestinal cells absorb this complex by receptor-mediated endocytosis
  • vitamin B12 is needed to synthesize hemoglobin: prevents pernicious anemia
  • secretion of intrinsic factor is the only indispensable function of the stomach
41
Q

functions of hydrochloric acid

A
  • activates pepsin and lingual lipase.
  • breaks up connective tissues and plant cell walls
  • converts ingested ferric ions (Fe3+) to ferrous ions (Fe2+)
  • contributes to nonspecific disease resistance by destroying most ingested pathogens
42
Q

gastric motility: how long does it take for food to leave the stomach? what about a fatty meal?

A

typical meal emptied from stomach in 4 hours. less time if the meal is more liquid. as long as 6 hours for a high fat meal.

43
Q

gastritis

A

inflammation of the stomach can lead to a peptic ulcer as pepsin and hydrochloric acid erode the stomach wall. most ulcers are caused by acid-resistant bacteria, Helicobacter pylori that can be treated with antibiotics and Pepto-Bismol.

44
Q

Gastroesophageal Reflux Disease (Gerd)

A
  • reflux normally prevented by lower esophageal sphincter.

- complications include: strictures in esophagus, ulceration, and increased cancer risk.

45
Q

functions of hepatocytes

A
  • after a meal, the hepatocytes absorb from the blood (glucose, amino acids, iron, vitamins, and other nutrients for metabolism or storage
  • removes and degrades (hormones, toxins, bile pigments, and drugs)
  • secretes into the blood (albumin, lipoproteins, clotting factors, angiotensinogen, and other products)
  • between meals, hepatocytes break down stored glycogen and releases glucose into the blood
46
Q

gallbladder

A

a pear-shaped sac on underside of liver

-stores and concentrates bile by a factor of 20 by absorbing water and electrolytes

47
Q

bile

A

yellow-green fluid containing minerals, cholesterol, neutral fats, phospholipids, bilt pigments, and bile acids

48
Q

bile acids (bile salts)

A

steroids synthesized from cholesterol
-bile acids and lecithin, a phospholipid, aid in fat digestion and absorption
-80% of bile acids are reabsorbed in the ileum and returned to the liver
20% of the bile acids excreted in the feces

49
Q

gallstones (biliary calculi)

A

hard masses in either the gallbladder or bile ducts. composed of cholesterol, calcium carbonate, and bilirubin

50
Q

Pancreas

A

both an endocrine and exocrine gland

51
Q

endocrine portion of pancreas

A

pancreatic islets that secrete insulin and glucagon

52
Q

exocrine portion of pancreas

A

99% of pancreas that secretes 1200 to 1500 mL of pancreatic juice per day
-secretory acini release their secretion into small ducts that converge on the main pancreatic duct

53
Q

Pancreatic Secretions

A

sodium bicarbonate -alkaline) raises pH of acidic chyme in duodenum
pancreatic amylase-digests starch
pancreatic lipase-digests fat
pancreatic protease-digests proteins (trypsin and chymotrypsin)

54
Q

what three stimuli are chiefly responsible for the release of pancreatic juice and bile?

A

acetylcholine (A Ch), cholecystokinin (CCK), and secretin

55
Q

acetycholine (A Ch)

A

from vagus and enteric nerves

-stimulates acini to secrete their enzymes during the cephalic phase of gastric control even before food is swallowed

56
Q

cholecystokinin (CCK)

A

secreted by mucosa of duodenum in response to arrival of fats in small intestine
-strongly stimulates gall bladder to discharge bile into duodenum

57
Q

secretin

A

released from duodenum in response to acidic chyme arriving from the stomach

  • stimulates ducts of both liver and pancreas to secrete more sodium bicarbonate
  • raising pH to level pancreatic and intestinal digestive enzymes require
  • Alkalyzing Secretions!!!
58
Q

what are the three regions of the small intestine?

A

duodenum, jejumun, and ileum

59
Q

duodenum

A

the first 25 cm (10 inches) of the small intestine.

  • receives stomach contents, pancreatic juice, and bile
  • pancreatic enzymes take over the job of chemical digestion
  • stomach acid is neutralized here
  • fats are physically broken up (emulsified) byt the bile acids
60
Q

jejunum

A

first 40% of small intestine beyond duodenum

-most digestion and nutrient absorption occurs here

61
Q

ileum

A

forms the last 60% of the postduodenal small intestine

62
Q

ilececal valve

A

sphincter formed by the thickened muscularis of the ileum

  • protrudes into the cecum
  • regulates passages of food residue into the large intestine
63
Q

Small Intestine Villi

A 
• Lipids (chylomicrons) are absorbed by
specialized lymphatic capillaries called
lacteals.
• Intestinal crypts are analagous to gastric
crypts
64
Q

what is the purpose of segmentation of the small intestine?

A

to mix and churn not to move material along as in peristalsis

65
Q

indigestible residue in large intestine

A

large intestine receives about 500 mL of indigestible residue per day
– reduces it to about 150 mL of feces by absorbing water and salts
– eliminates feces by defecation

66
Q

anatomy of the large intestine

A

ascending colon, right colic (hepatic) flexure, transverse colon, left colic (splenic) flexure, and descending colon frame the small intestine
– sigmoid colon is S-shaped portion leading down into pelvis
-rectum - portion ending at anal canal
-anal canal – final 3 cm of the large intestine

67
Q

rectum

A

portion ending at anal canal

• has 3 curves and 3 infoldings the transverse rectal folds(rectal valves)

68
Q

anal canal

A

final 3 cm of the large intestine
-passes through levator ani muscle and pelvic floor
• terminates at the anus
• anal columns and sinuses – exude mucus and lubricant into anal canal during defecation
-large hemorrhoidal veins for superficial plexus in anal columns and around orifice

69
Q

hemorrhoids

A

permanently distended veins that protrude into the anal canal or form bulges external to the anus

Western Medicine 502 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions