⛤Digestion⛤

Front 1

Mechanical digestion

Back 1

-brought about by mastication (in the oral cavity) and the smooth muscle contractions in the alimentary canal

Front 2

Mastication

Back 2

-chewing, the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes.

Front 3

Peristaltic waves

Back 3

->contractions move the food bolus through the esophagus to the stomach.

->involuntary movements of the longitudinal and circular muscles,

->Peristaltic waves occur in the esophagus, stomach, and intestines.

---smooth muscle tissue contracts in sequence to produce a peristaltic wave, which propels a ball of food (called a bolus while in the esophagus and upper gastrointestinal tract and chyme in the stomach) along the tract.

Front 4

Chyme

Back 4

thick semifluid mass of partially digested food and digestive secretions that is formed in the stomach and intestine during digestion.

--mix the food with the chemical digestive processes fr. Stomach..

Bolus turns to Chyme

Front 5

Segmentation Contractions.

Back 5

occurs in both the large and small intestine, but mostly in the small intestine. Segmentation is a contraction of circular muscles that surround the intestine. It helps digest the chyme, which is what is left of our digesting food, along with stomach enzymes, as it enters the duodenum from the stomach

Front 6

Interstitial Cells of Cajal (enteric brain)

Back 6

serve as a pacemaker which creates the bioelectrical slow wave potential that leads to contraction of the smooth muscle. Intramuscular Interstitial cells of Cajal (ICC-IM) are involved in the stimulation of smooth muscle cells, neurotransmitters act through them.

-----------contractions are under the control of the interstitial cells of Cajal (enteric brain)

mediate the motility of different portions of the alimentary canel(passage along which food passes through the body from mouth to anus,aka digestive tract).

Front 7

Colon possesses WHAT 2 major motor activities..

Back 7

segmentation and peristalsis(Contractions move the bolus through the large intestine to the rectum, where waste can be stored for a brief time)..

Front 8

Distention

Back 8

Ingestion of food elicits activity in the colon, which then moves the stool by mass action into the rectum. The distention of the rectal wall initiates the defecation reflex. This is the reason that eating causes the urge to defecate.

state of being distended, enlarged, swollen from internal pressure.

Front 9

Defecation Reflex

Back 9

first step occurs when a mass movement triggers a defecation reflex. A mass movement is a maintained, high-intensity contraction of the circular muscle in the colon, which will propel feces toward the rectum.

Front 10

Chemical Digestion of food is necessary for?...

Back 10

⛤➡nutrient absorption....

involves the catabolic breakdown of polymers into monomers, which are small enough to be absorbed by the intestinal mucos

Front 11

Catabolic

Back 11

breakdown of polymers into monomers, which are small enough to be absorbed by the intestinal mucosa. This catabolism is mediated by enzymes and other chemicals produced within the gastrointestinal tract (GI tract) and its accessory organ.

mediating agent (as an enzyme or hormone) in a chemical or biological process

enzymes aid in hydrolysis reactions, and require specific environmental conditions to exert their optimal effect. The effectiveness of a particular enzyme is determined by the temperature, pH, and enzyme to substrate ratio along the GI tract.

Front 12

CATABOLISM: what kind of reaction does these enzymes do?.

Back 12

➡enzymes aid in "Hydrolysis Reactions", and require specific environmental conditions to exert their optimal effect. The effectiveness of a particular enzyme is determined by theTemperature,

PH, and enzyme to substrate ratio along the GI tract.

Front 13

hydrolysis reactions,

Back 13

reaction involving the breaking of a bond in a molecule using water.

-Catabolism

-breakdown of polymers into monomers,

Front 14

Effectiveness of a particular enzyme is determined by?

Back 14

temperature, pH, and enzyme to substrate ratio along the GI tract

Front 15

Carboydrate digestion

Back 15

-begins in the mouth with salivary amylase.

-stops digestion in stomach becuz pH difference..

- digestion continues in the duodenum through the action of pancreatic amylase.

Front 16

Salivary Amylase

Back 16

--Secreted in salivafrom salivary glands (parotid, submandibular, and sublingual glands),

--it begins to break down starch into maltose.

--The mouth has a pH near 7, which is the optimum for salivary amylase

--action of salivary amylase is stopped by the low pH of the gastric juice in the stomach (pH of around 2).

Front 17

Pancreatic Amylase.

Back 17

--Pancreatic enzyme

--Starch digestion continues in the duodenum

--This enzyme mediates the hydrolysis of starch into maltose (disaccharide), maltotriose (trisaccharide), and branched oligosaccharides.

Front 18

Many dietary carbohydrates are in the form of disaccharides & do not begin digestion until reaching?....... where?..

Back 18

--- sucrose (table sugar), lactose (milk sugar), and maltose (grain sugar).

----

These do not begin digestion until reaching the duodenum. In order for absorption to take place, the brush border enzymes s located in the apical surface plasma membrane of the small intestinal mucosal cells must hydrolyze these larger molecules.

➡enzyme Sucrase digests Sucrose into glucose and fructose.

➡enzyme Lactase digests Lactose into glucose and galactose.

➡ enzyme Maltase digests Maltose into two glucose molecules

Front 19

Protein digestion begins ?..

Back 19

--in the stomach with the combined actions of the enzyme pepsin and the chemical hydrochloric acid.

Front 20

zymogen

Back 20

inactive enzyme,

Front 21

Pepsinogen,

Back 21

--zymogen or inactive enzyme, is secreted by the chief cells in the gastric pits.

In order to become the active pepsin, pepsinogen requires an acid environment. This is provided by the parietal cells, also located in the gastric pits, which secrete HCl

Front 22

parietal cells

Back 22

secrete HCl under stimulation by the paracrine hormone histamine (released from the ECL cells by gastrin and the parasympathetic nervous system)

Paracrine signaling is a form of cell-to-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behavior of those cells.

Front 23

As chyme exits the stomach and enters the duodenum, the HCl is neutralized??....

Back 23

by the alkaline pH of pancreatic juice and pepsin becomes inactive. Protein digestion continues however, mediated by the proteinases (enzyme) in pancreatic juice and in the brush border enzymes.

Front 24

Where are trypsinogen, chymotrypsinogen, and procarboxypeptidase are secreted from??.

Back 24

PANCREASe

Front 25

enterokinase converts trypsinogen into trypsin. Trypsin catalyzes the conversion of chymotrypsinogen and procarboxypeptidase to chymotrypsin and carboxypeptidase,

Back 25

Enterokinase.

Front 26

What does Trypsin and chymotrypsin do??...

Back 26

Trypsin and chymotrypsin form short polypeptides, dipeptides, and some free amino acid

Front 27

What does Carboxypeptidase do amd aminopepdidase

Back 27

Carboxypeptidase works at the carboxyl end of a protein and breaks off one amino acid at a time. It is also a brush border enzyme. Another brush border enzyme is aminopeptidase, which works at the amino end of a polypeptide chain and, like carboxypeptidase, cleaves off one amino acid at a time

Front 28

Lipid digestion

Back 28

--does not occur until the duodenum. Because lipids are hydrophobic, they do not mix with the chyme; instead they float on the surface.

Front 29

Very low density lipoproteins (VLDLs)

Back 29

Very low density lipoproteins (VLDLs) transport endogenous triglycerides (fats made by the liver) to body cells.

Front 30

Low density lipoproteins (LDLs)

Back 30

Low density lipoproteins (LDLs) transport endogenous cholesterol to organs, including blood vessels.

Front 31

High density lipoproteins (HDLs)

Back 31

High density lipoproteins (HDLs) remove cholesterol from organs and return it to the liver.

-----Experts believe HDL acts as a scavenger, carrying LDL cholesterol away from the arteries and back to the liver.

Front 32

lipoproteins

Back 32

Molecules called lipoproteins carry cholesterol in the blood. Two important kinds of lipoproteins are low-density lipoprotein (LDL) and high-density lipoprotein (HDL)

Front 33

pancreatic nucleases.

Back 33

The nucleic acids are hydrolyzed into nucleic monomers by pancreatic nucleases.

Pancreatic nucleases enter the duodenum in the pancreatic juice

Front 34

wat are the nucleic acid brush border enzymes..?

Back 34

Brush border enzymes called "Nucleosidases" and "Phosphatases" break down the nucleotides into free bases, pentose sugars, and phosphate groups. These products are actively transported into the epithelial cells and move into the blood capillaries. The products then enter the liver via the hepatic portal system.

Front 35

Nucleic Acid digestion

Back 35

Occure in the small intestine by pancrease enzyme and brush border

Front 36

Fat soluble vitamin

Back 36

Fat soluble vitamin (A, D, E, and K) absorption is coupled with the absorption of lipids. These vitamins dissolve readily in fat droplets and are incorporated into micelles.

Front 37

Water soluble vitamin

Back 37

Water soluble vitamin (B vitamins and C) are absorbed by diffusion, except for B12. It must bind to intrinsic factor secreted by the stomach to be absorbed in the ileum. B12 is required for the synthesis of hemoglobin, so a deficiency in this vitamin causes pernicious anemia. Gastric ulcers can also lead to this anemia by interfering with the production of intrinsic factor.

Front 38

B12

B12

Back 38

B12. It must bind to "intrinsic factor" secreted by the stomach to be absorbed in the ileum. B12 is required for the "synthesis" of hemoglobin, so a deficiency in this vitamin causes "pernicious anemia." Gastric ulcers can also lead to this anemia by interfering with the production of intrinsic factor

Front 39

Electrolyte absorption

Back 39

Electrolyte absorption occurs along the small intestine.

Front 40

Benedict’s Test.

Back 40

Maltose and glucose are referred to as reducing sugars and can be detected using the Benedict’s Test.

Benedict’s reagent can be used to determine if maltose is present.

Blue - (no maltose)

Green +

Yellow ++

Orange +++

Red ++++ (most maltose)

Front 41

Lugol’s iodine

Back 41

Lugol’s iodine can be used to determine if starch is still present..

Dark blue/black => positive (+) for starch..

Reddish/ orange => negative (-) for starch...

Dark blue/black colors indicate the presence of starch while green, yellow, orange, and red colors indicate the presence of maltos...

Front 42

Digestion by Trypsin (of BAPNA)

Back 42

optical density (absorbance) of the solution can be measured using a spectrophotometer. The more ‘yellow’ the solution, the higher the absorbance reading, and therefore the more digestion of BAPNA by trypsin has occurred.

Front 43

pancreatin solution

Back 43

pancreatin solution (which contains the proteolytic enzyme trypsin) to digest a chromogenic (color producing compound) substrate called BAPNA. BAPNA is a colorless ester that is recognized by trypsin as a substrate, and when trypsin cleaves the p-nitroaniline group from the compound, the solution turns yellow.

Front 44

Phenol red

Back 44

pH indicator

----red=> basic

---yellow=> acidic

As the lipids are enzymatically digested by lipase, fatty acids are released and the pH of the solution decreases. Using "phenol red" as an indicator, we can observe directly the change in pH as the solution changes from red (basic solutions) to "yellow (acidic solutions). "