Physio (Final)

Front 1

define digestion

Back 1

the chemical and mechanical breakdown of foods into smaller units that can be taken across the intestinal epithelium into the body

Front 2

define absorption

Back 2

the active or passive transfer of substances from the lumen of the GI tract to the extracellular fluid

Front 3

define motility

Back 3

the movement of material from teh lumen to the GI tract as a result of muscle contraction.

Front 4

define secretion

Back 4

refers to both the transepithelial transfer of water and ions from the ECF to the digestive tract lumen and the release of substances synthesized by GI epithelial cells.

Front 5

what is the GALT and where is it located?

Back 5

gut-associated lymphoid tissue, ~80% of all lymphocytes are here in the small intestine

Front 6

what are the three pairs of salivary glands?

Back 6

sublingual (under the tongue)
submandibular (under the mandible)
parotid (lying near the hinge of the jaw)

Front 7

what are the three parts of the stomach?

Back 7

the upper fundus, central body, and lower antrum

Front 8

what is the opening of the stomach and the small intestine guarded by?

Back 8

pyloric valve or pyloris

Front 9

what does the small intestine consist of

Back 9

the duodenum, jejunum, and ileum respectively

Front 10

what are the two accessory glandular organs?

Back 10

the pancreas and the liver

Front 11

what is the function of the sphincter of oddi?

Back 11

to control pancreatic fluid and bile from entering the duodenum

Front 12

what are the four layers of the stomach?

Back 12

1. inner mucosa
2. submucosa
3. muscularis externa
4. serosa

Front 13

what are the three layers of the mucosa?

Back 13

1. single layer of epithelial cells
2. the lamina propria
3. muscularis mucosae

Front 14

lamina propria

Back 14

subepithelial connective tissue that holds the epithelium in place

Front 15

rugae

Back 15

folds in the wall of the stomach

Front 16

plicae

Back 16

folds in the wall of the small intestine

Front 17

villi

Back 17

fingerlike extensions in the intestinal mucosae

Front 18

gastric glands

Back 18

invaginations of the stomach wall

Front 19

crypts

Back 19

invaginations of the intestinal wall

Front 20

submucosal glands

Back 20

deepest invaginations from secretory glands that open into the lumen through ducts.

Front 21

what is the function of transporting epithelial cells

Back 21

they move ions and water inot the lumen and absorb ions, water, and nutrients into the ECF, at the mucosal (apical)surface

Front 22

what is the function of secretory cells?

Back 22

they release enzymes, mucus, and paracrine molecules into the lumen at the basolateral surface

Front 23

why is the interstitial epithelium considered to be leaky?

Back 23

because some water and solutes can be absorbed between the cells

Front 24

what is the function of GI stem cells?

Back 24

they are rapidly dividing, undiffentiated cells that continuously produce new epithelium in the crypts and gastric glands

Front 25

lamina propria

Back 25

is subepithelial connective tissue that contains nerve fibers and small blood and lymph vessels into which absorbed nutrients pass. This layer also contains wandering immune cells such as macrophages and lymphocytes

Front 26

peyers patch

Back 26

small nodules formed in the intestine from lymphnoid tissue adjoining the epithelium

Front 27

muscularis mucosae

Back 27

seperates the mucosa from the submucosa. contraction of this layer alters the effective surface area for absorption by moving the villi back and forth

Front 28

what are the two nerve networks in the enteric system?

Back 28

submucosal plexus and the myenteric plexus

Front 29

the muscularis externa consists of what types of muscles?

Back 29

two layers of smooth muscle
an inner circular layer
and an outer longitudinal layer

Front 30

what nerve plexus controls and coordinates the motor activity of the muscularis externa?

Back 30

myenteric plexus

Front 31

what is the outer covering of the entire digestive tract?

Back 31

serosa

Front 32

what is the serosa an extension of?

Back 32

the peritoneal membrane

Front 33

what are the sheets called that hold the intestines in place so that they don't become tangled?

Back 33

mesentary

Front 34

what are the two purposes of motility in the GI tract?

Back 34

1. moving food from the mouth to the anus.
2. mechanically mixing food to break it into uniformly small particles.

Front 35

tonic contractions

Back 35

are sustained for a few minutes or hours occur in some smooth muscle spinchters and in the anterior portion of the stomach

Front 36

phastic contractions

Back 36

contraction-relaxation cycles lasting only a few seconds, occur in the posterior region of the stomach and in the small intestine

Front 37

slow wave potentials

Back 37

cycles of smooth muscle contraction and relaxation are associated with depolarization and repolarization

Front 38

interstitial cells of cajal

Back 38

slow waves originate in modified smooth muscle cells called cells of cajal and pass into smooth muscle cells through gap junctions

Front 39

migrating motor complex

Back 39

between meals when the tract is largely empty, a series of contractions begins in the stomach and passes slowly from section to section, each taking about 90 minutes. AKA housekeeper function that sweeps food remnants and bacterial out of the upper GI into the large intestine

Front 40

Peristalsis

Back 40

progressive waves of contraction that move from one section of the GI tact to the next. Circular muscles contract just behind a mass or bolus of food. This pushes the bolus foward into a receiving segment.

Front 41

segmental contractions

Back 41

segments of the intestine alternately contract and relax. Circular muscles contract while longitudinal muscles relax. this causes mixing and contact with the absorptive epithelium

Front 42

in a typical day, how many liters of fluid pass through the lumen of a GI tract. How much of that is excreted

Back 42

9 liters
.1 liters excreted

Front 43

what happens during acid secretion?

Back 43

1. H+ from inside the parital cell is pumped into the stomach lumen by a H+-K+-ATPase in exchange for K+.
2. Cl- follows H+ through an open chloride channel
3. HCl stays in the lumen
4. HCO3- goes to the blood, made from CO2 and OH-

Front 44

what is the alkaline tide?

Back 44

from acid secretion, bicarbonate is formed in the parietal cells and then goes to the blood

Front 45

what is the purpose of bicarbonate secretion?

Back 45

to secrete bicarbonate into the exocrine pancreas and the duodenum.

Front 46

what is the enzyme needed for production of bicarbonate?

Back 46

carbonic- anhydrase

Front 47

what is exchanged for what for bicarbonate secretion on the apical membrane (lumen of pancreas)

Back 47

HCO3- for Cl

Front 48

what is exchanged for what for bicarbonate secretion on the basolateral membrane (interstitial fluid)

Back 48

H+ is exchanged for Na+

Front 49

acini

Back 49

lobules in the exocrine portion of the pancreas that secrete digestive enzymes, and duct cells secrete NaHCO3.

Front 50

what secretes NaCl in the digestive tract?

Back 50

crypt cells in the small intestine and colon secrete an isotonic NaCl solution

Front 51

what is the active step in NaCl secretion?

Back 51

Cl- secretion, followed by Na+ and water moving through the paracellular pathway.

Front 52

how does chloride enter the cell in NaCl secretion?

Back 52

through NKCC transporter

Front 53

how does chloride exit the cell in NaCl secretion?

Back 53

via an apical CFTR channel.

Front 54

what is the purpose of NaCl secretion?

Back 54

the saline mixes w/ mucus secreted by goblet cells to help lubricate the contents of the gut.

Front 55

mucins

Back 55

the glycoproteins that make up mucus

Front 56

mucus is made in what 3 places?

Back 56

1. mucus cells in the stomach
2. goblet cells in the intestine
3. salivary glands

Front 57

what are the 3 key components of bile?

Back 57

1. bile salts that facilitate enzymatic fat digestion
2. bile pigments such as bilirubin are waste products of hemoglobin degradation
3. cholesterol which is excreted in the feces

Front 58

what are bile salts made of?

Back 58

steroid bile acids and amino acids which act as detergents to solubulize fats during digestion.

Front 59

what is saliva composed of?

Back 59

water, ions, mucus and proteins such as enzymes and immunoglobuluins

Front 60

which part of the autonomic system controls saliva secretion?

Back 60

parasympathetic innervation is the primary stimulus for secretion of saliva

Front 61

how are carbohydrates digested in the saliva?

Back 61

amylase breaks starch down to sugar (Maltose)

Front 62

how are carbohydrates digested in the stomach?

Back 62

acid denatures amylase

Front 63

how are carbohydrates digested in the duodenum?

Back 63

pancreatic amylase continues to break down dissacharides. the process of chyme entering the small intestine activates CCK which tells the pancreas to secrete pancreatic enzymes

Front 64

what are the brush border enzymes in the small intestine used to break down carbohydrates?

Back 64

lactase
maltase
sucrase
which completes the breakdown of dissacharides to monosacharides

Front 65

what absorbs the monosaccharides after they are broken down by the carbohydrate enzymes?

Back 65

the liver

Front 66

what are the three major pancreatic proteases?

Back 66

Trypsin, Chymotrysin, and Carboxypeptidase

Front 67

how do trypsin and chymotrypsin break down proteins?

Back 67

cleave proteins into smaller peptides and single amino acids

Front 68

how does carboxypeptidase break down peptides?

Back 68

cleaves on amino acid at a time for the carboxyl end of a protein

Front 69

Aminopeptidase and dipeptidase

Back 69

futher break down di and tri peptides

Front 70

are di and tri peptides absorbed?

Back 70

yes

Front 71

where does fatty acid digestion take place?

Back 71

in the small intestine

Front 72

what is the enzyme that breaks down triglycerides?

Back 72

pancreatic lipase

Front 73

what helps to break down large fat drops into smaller dorps in the small intestine?

Back 73

segmentation

Front 74

what enzyme digests glyercides?

Back 74

lipase

Front 75

how do bile salts break down lipid droplets?

Back 75

they hydrophobic regions of bile salts associate with the surface of lipid droplets. While the polar side chains interact with water, creating a stable emulsion of small water-soluble fat droplets.

Front 76

colipase

Back 76

a protein cofactor secreted by the pancreas it diplaces bile salt, thus allowing lipase to access the fats inside the bile salt coating

Front 77

chylomicrons

Back 77

once the micelle is absorbed, they are resynthsized into triglycerides and combine with cholesterol and proteins to form chylomicrons.

Front 78

lacteals

Back 78

lymph vessels that chylomicrons move through b/c they are too large to go anywhere else.