Biol 111: Chapter 39
What are the three stomach digestive functions?
-Stores food and controls the rate of passage to the small intestine. -Mechanically mixes and breaks down food. -Secretes substance use in chemical digestion.
Mammal adaptations:
-Teeth adapted to different diets -Multiple stomach chambers in ruminants -Carnivore has a shorter gut than grazers
____________ are actively transported into a brush border cell, then into interstitial fluid inside a villus, then enter blood.
Monosaccharides
Major Organs
Mouth Esophagus Stomach Small Intestine Large Intestine Rectum Anus
What does the complete digestive system include?
Mouth, pharynx, esophagus, stomach, small and large intestines, and anus.
What are the functions of the stomach?
The stomach receives food from the esophagus and stretches to store it.
Pharynx
Throat
Fluid Absorption: Step 1
Transport proteins move salts, sugars, and amino acids from the intestinal lumen, into brush border cells, then into an interstitial fluid in a villus.
Fat Absorption: Step 3
Triglycerides combine into proteins to make lipoproteins.
Food is moved through the _________ by peristalsis through a sphincter to the ______, which adds acids and enzymes to food and mixes them together.
esophagus, stomach
The ______ ______ is wider than the small intestine, but also much shorter. (only about 1.5 meters (5 ft.) long)
large intestine
The ______ _______ absorbs water and ions, and compacts wastes, which collect in the rectum, and are expelled from the anus.
large intestine
Food is _______ digested in the mouth and _____ into the pharynx by swallowing.
partially, forces
Bolus
One swallow of food.
In the small intestine, chyme mixes with secretions from the _________ and _____.
pancreas and liver
Enzymes embedded in the _______ membrane of the brush border cells split disaccharides into monosaccharide.
plasma
In the small intestine, pancreatic amylase breaks down ____________.
polysaccharides
Stretch ________ in the rectum trigger the defeaction reflex.
receptors
Protein digestion began in the _________, where pepsin broke proteins into polypeptides.
stomach
The ________ is a muscular, stretchable sac with a sphincter at either end.
stomach
How many digestive functions does the stomach have?
three
______ ______ cells function in both digestion and absorption.
Brush border
In the ______, salivary amylase broke polysaccharides into disaccharides.
mouth
Stomach ______ secretes gastric fluid containing hydrochloric acid and enzymes that begin protein digestion.
mucosa
Human have a complete digestive system lined with _____ ______ ________.
mucus-covered epithelium
Function of Brush Border Cells:
-Digestive enzymes at the surface of a microvillus break down sugars, protein fragments, and nucleotides. -Many transport proteins facilitate the movement of nutrients into the microvillus.
Digestion in the Stomach
-Gastrin signals secretion of acid and pepsinogens -Acid unfolds proteins -Pepsin breaks proteins into peptides
Bird adaptations:
-Size and shape of beaks adapted to different diets -Crops and gizzards
Digestive System
A body cavity or tube that mechanically and chemically breaks food down to small particles, then to molecules that can be absorbed into the internal enivornment.
Emulsifiaction
A mixture of fat and water.
Incomplete digestive system
A saclike gut with one opening in the body surface for food to enter and waste to leave.
HDL
High-density lipoproteins (Good cholesterol).
The ________ ______ starts at the stomach and extends through the intestines to the terminal opening.
gastrointestinal tract
Many folds and projections of the small intestinal lining ______ its surface area for absorption.
increase
Emulsifier
A substance that stabilizes emulsifications amphipathic.
Complete digestive system
A tubular gut with an opening at both ends.
Planarian
A type of flatworm. (an example of incomplete digestive system)
Fourth function of Complete Function System
Absorption of nutrients into extracellular fluid.
_______ ______ positioned adjacent to the gut secrete substances into its interior. These substances aid in digestion of food and absorption.
Accessory organs
_______ in the colon make vitamin B12, which is absorbed through the colon lining.
Bacteria
Interstitial
Between cells
____ is a mixture of salts, pigments, cholesterol, and lipids that emulsifies fats into small drops that enzymes can break down into fatty acids and monoglycerides.
Bile
Fluid Absorption: Step 3
Capillaries in the virus distribute water and solutes through the body.
________ digestion of proteins begins in the stomach.
Chemical
_______ passes into the small intestine.
Chyme
Esophagus
Connects the pharynx and stomach.
__________ of stomach muscles break up food and mix it with acidic gastric fluid. They also move the resulting mixture (the chyme) into the small intestine.
Contractions
Herbivore
Designed for grinding. Think enamel. Longer gut.
Carnivore
Designed for tearing. Thin enamel. Shorter gut.
________ begins when teeth mechanically break down food into smaller bits.
Digestion
Third function of a Complete Function System
Digestion of food into absorbable molecules.
Fifth function of Complete Function System
Elimination of solid residues.
Fat Absorption: Step 1
Fatty acids and monoglycerides combine with bile salts to form micelles, which aid diffusion into brush cells (bile salts stay in the lumen).
What type of digestive system do humans have?
Humans have a complete digestive system with a tubular, mucosa-lined gut.
Fat Absorption: Step 2
In the brush border cells, monoglycerides and free fatty acids recombine into triglycerides.
Chyme
Is a mixture of food and gastric juices in the stomach.
________ (fat) digestion in the small intestine requires enzymes and bile, which produces by the liver and stored in the gallbladder.
Lipid
Fat Absorption: Step 4
Lipoproteins enter the interstitial fluid by endocytosis.
Fat Absorption: Step 6
Lipoproteins in the interstitial fluid enter the lymphatic system, then the circulatory system.
LDL
Low-density lipoproteins (Low cholesterol).
One function of a Complete Digestive System
Mechanical processing and motility.
__________ enzymes break down larger molecules into units that can be absorbed.
Pancreatic
Sphincter
Ring-like muscle that is located at either end of the stomach.
Accessory Organs
Salivary Glands Pharynx Liver Gallbladder Pancreas
Second function of a Complete Digestive System
Secretion of digestive enzymes into the lumen.
Fluid Absorption: Step
Water follows the solutes by osmotic gradient.
Peristalsis
Wave-like contraction that forces food down the esophagus.
The large intestine completes the process of _______ then ________ _____, and compacts them as feces.
absorption, concentrates wastes
The _________ colon begins at the cecum, where the appendix is attached.
ascending
Structural variations in ____, _____, and ______ of the gut and adaptations that allow an animal to exploit a particular type of types of food.
bills, teeth, and regions
Teeth consist mostly of ________ ______; the crown is covered by a hard layer of enamel.
bonelike dentin
Enzymes at the surface of brush border cell break peptide fragments into amino acids, which are actively transported into ________ _____ _____, ___________ _______, and ______.
brush border cells, interstitial fluid, and blood
The ___ completes the process of absorption, then concentrates, stores, and eliminates wastes.
colon
The _______ colon attaches to the rectum.
descending
Most __________ and __________ take place at the surface of the small intestine.
digestion and absorption
Accessory organs such as _________ ______, _______,______, and ________ secrete enzymes and other substances that aid in the breakdown of food and absorption of nutrients.
salivary glands, pancreas, liver, and gallbladder
In the _____ _______, carbohydrates, lipids and proteins are digested by secretions from liver and pancreas; nutrients and water are absorbed.
small intestine
Is statement true for the small or large intestine? Brush border cells at the surface have membrane extensions (microvilli) that project into the lumen.
small intestine
Is this statement true for the small or large intestine? Multicelled, fingerlike absorptive structures (villi) with lymph and blood vessels extend from folds.
small intestine
Most fluid that enters the gut is also absorbed across the wall of the _____ _______.
small intestine
The _____ ______ has a highly folded lining with many projections that make its surface area enormous.
small intestine
Salivary amylase secreted by salivary glands begins the breakdown of _______.
starch