bio 20, digestive system 8.3-4

what are the 4 processes of digestion

1. mechanical

2. chemical

3. absorption

4. assimilation

explain mechanical digestion

the physical breaking down of food into smaller segments, a physical change to increase surface area, allowing for better chemical digestion

explain chemical digestion

the breakdown of food by enzymes a the molecular level, prepares monomers for absorption

explain absorption

the taking in of monomers into the bloodstream and lymphatic system

explain assimilation

the use of monomers with the cells of the body. monomers can be used to build large molecules, directly as in the case of glucose or stored for later use.

please go draw the schematic for the anatomy of the digestive system. indicate what the alimentary canel is.

this is me daring the digestive system

please label the anatomy of the digestive system

this is me labeling the digestive system

explain the role of the mouth in digestion

physically --> food is broken down by the teeth in a process called mastication and is mixed with salvia
chemically --> salivary amylase is present in salvia, which begins the digestion of starch to maltose. the pH is 7, best for this enzyme!

Explain the role of the esophagus

the food passes through the esophagus as a bolus, it is transported to the stomach by a sequence of muscles contractions know as PERISTALSIS

what is salivary amylase

enzyme that begins starch digestion in the mouth to maltose. does NOT fully digest starch.

What is peristalsis?

A sequence of muscle contractions known as peristalsis

Explain the role of the stomach in digestion.

a muscular sac that holds holds the food.
physically --> muscle contractions mix HCI, food and enzymes together, to give max contact between food and enzyme molecules to speed up chemical digestion
chemically --> site of the digestion of protein. HCI actives the enzyme pepsin, which acts on the protein molecules in the food, turning them into peptide chains

• ph. 1.5-2

• secretes mucus to protect interior of stomach from acid and enzymes, preventing ulcers.

• NOT PRIMARY SITE OF DIGESTION

explain what pepsinogen/pepsin is in the stomach

• pepsin is an enzyme that digests proteins,

• present in gastric juices. It is stored in an inactive form, pepsinogen

• and is activated by HCI on the stomach

lacteal

a lymph tubule located in the villus that absorbs fatty acids

capilliary

A narrow blood vessel that connects with arteries and viens

what is the small intestines role in digestion

• a long thin tube in-between the stomach and intestine

• primary site of digestion

• made of 3 regions: the duodenum, jejunum, ileum.

what is the role of the duodenum

firest section of small intestine

• main site of digestion

• digestive judices are secreted from the liver, gall bladder, pancreas and duodenal walls.

• some absorption occurs

What is the role of the jejunum?

primary site of absorption,

• as monomers come into contact with the wall of the jejunum they are absorbed via active of passive transport into the blood or lymphatic system

• some digestion occurs

what is the role of ileum

Final portion of the small intestine, absorbs B12 and bile salts and anything else not absorbed by jejunum. Empties into the large intestine.

• some digestion occurs

what does the liver do in digestion

produces bile that emulsifies fats

what does the gall bladder do in digestion

stores bile before it's released into the small intestine

what does the pancreas do in digestion

Produces enzymes for breaking down food, and neutralize stomach acid by producing bicarbonate

what is chyme

a mixture of partially digested food, water, and gastric juices from the stomach

how is chyme neutralized

by bicarbonate created in the pancreas

explain why emulsification is necessary to digest lipids

• lipids will form large groups called globules, since lipids are insoluble and lipase is water soluble, the lipase can only hydrolyze the outer side of the lipid globules

• by combining with bile salts, many more small droplets of fat are created, increasing surface area.

• this speeds up the digestion process and allows lipids to be complete digested in the small intestine

please draw the process of lipid digestion

this is me drawing the process of lipid digestion

explain the process of protein digesting

in the stomach, small polypeptide chains are created from proteins. they enter the duodenum and are broken down by proteases (pancreatic enzymes) creating even smaller poly peptides. peptidases (erepsin) are released and digest the chain to create amino acids.

please draw the process of digestion of proteins

this is me drawing the digestion of proteins

explain the digestion of carbohydrates

starch is partially broken down in the mouth, into disaccarches.

• pancreatic amylase (pancreas produces) breaks down remaining starch to disaccharides

• remaining starch and disaccharides enter the duoduem and are broken down by carbohydrase's (produced in pancreases).

• a bunch of diff enzymes convert disaccharides to monosaccharides, they are embedded in the membrane of the duodenum.

please draw the digestion of carbohydrates

this is me drawing the digestion of carbohydrates

explain what increases the aborption of nutrients in the small intestine

By increasing SA you increase absorption

1. long tubes

2. ruggaes

3. villi's

4. micro villis

explain the absorption of glucose

monosaccharides are absorbed via active transport, through the epithelial cells, and diffuse into the blood vessels

explain the aborption of amino acids

amino acids are absorbed through the epithelial cells via active transport and are diffused into the blood vessels

explain the absorption of fatty acids and glyverol.

1. glycerol and fatty acids absorbed via passive transport through the eptheial cells,

2. they resemble back into triglycerides

3. they are protein coated making them more soluble,

4. they diffuse into the lymph vessels.

explain the anamotmt of a villi and micro villi

villi are little tentacles on the digestive walls to increase surface area. on the villi are even more tentacles called micro villi. they are composed of a one cell thick wall, the epithelium, to aid with diffusion rate. a blood capillary which transports glucose and amino acids, and lacteals which transport fats.

please draw a micro villi

this is me drawing a microvilli

what is the purpose of the large intestine

absorb water, pass undigested material, absorp minerals and create feces. also removes mucus, naturally occuring bacteria and dead cells.

what is the role of cellulose in our diets

humans cannot digest cellulose, a material that makes up the walls of plant cells. Because of this it is the ideal material for increasing the bulk of the feces passing through the digestive track, keeping the track clear and allowing for the smooth passage of waste.

what does gastrin do

stimulates the release of HCI when food enters the stomach and touches the stomach lining

what does enterogastrone do?

decreases gastric juice production in the stomach when fatty meals are detected, slowing down digestion to give time for fat emulfication/digestion

what CCK do (Cholecystokinin)

Stimulates the release of bile salts when fatty chyme is releases into the duodenum

what does secretin do

simulates the release of pancreatic enzymes and bicarbonate as acidic chyme enters the duodenum.

where are lipase from

it is secreted by the pancreas

what activates trypsinogen

enterokinase/endopeptidase

what is dehydration synthesis/condensation reaction

a chemical reaction that links molecular units by removing H2O. creating by removing water

what is hydolysis

the adding of H2O to break covalent bonds. breaking by adding water

how to detect lipids in a solotuion

1. paper bag test

2. sudan IV test

turns red in presence of lipids

how to detect starch in a solution

use iodine —> turn from orange to dark black

how to detect proteins in a solution

biuret test —> blue to violet

how to detect mono/disaccarides

benedicts solution + heat, turn from blue to red, yellow, brown, green

what are the 3 carbohydrases

1. lactases

2. maltase

3. sucrases