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Digestive System
http://health.howstuffworks.com/adam-200142.htm
Swenson
Salivary Glands
a. Secrete enzyme amylase (breaks down carbs)
b. cover food to produce bolus (Mucous lubricates food)
Tongue
a. moves food side to side to be chewed and keeps between teeth
b. moves bolus to back of throat
c. closes off mouth when swallowing
Trachea
A. Wind Pipe
B. Epiglottis – flap of skin that covers the trachea so food does not enter the wind pipe and cause you to choke.
Esophagus
a. Food to the stomach by peristalsis
Liver
a. produces and secretes bile which emulsifies fats
b. detoxifies blood
c. stores glycogen (animal form of starch)
d. Reduces/neutralizes acidse. bile breaks up fats
Gall Bladder
a. Stores bile
Stomach
a. churn/mix foodb. digestion of proteins starts herec. Gastric juice is acidic (HCl) and
contains pepsin (enzyme to digest proteins)
d. Gastrin (hormone) stimulates to release of gastric juice
e. vomiting-reverse peristalsisf. pyloric sphincter controls opening
and end of stomach
Bile Duct
a. duct or tube from gall bladder to small intestine
Trachea
a. wind pipe
b. protected by epiglottis during swallowing (covering)
Small Intestinea. 20 – 30 feet long b. parts of sm. Intestine are:c. duodenum – listed aboved. jejunum – has folds of skin
called the brush border membrane.
e. ileum – selective absorption of some nutrients. What remains is liquid stool
f. Final digestion occurs hereg. food is absorbed in simplest
forms – amino acids, fatty acids, glycerole.
h. Villi – small finger like projects that contain vessels to absorb food
Duodenum
a. Most of the digestion begins here (proteins, fats and carbs)
Pancreas
a. produces powerful digestive enzymes
b. Produces and secretes insulin – important in regulating blood sugar levels
Pancreas Duct a. A duct or tube from pancreas to small intestine
Appendix
Vestigial organ – “dead end”
a. May at one time have aided in digestion of cellulose but has no function today
Large Intestine (colon)a. Parts are: Cecum – large
entrance controlled by a sphincter that protects the small intestine from the large intestines concentrated bacteria,
b. Ascending colon – upwards,
c. Transverse colon – across, d. descending colon – down, e. sigmoid colon – end
f. reabsorbs waterg. Some solid wastes are stored before they enter rectum
Rectum
Rectum
a. Stores solid waste until full Anus
a. Controlled by sphincter muscle by peristalsis.
Digestion animation review
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter26/animation__organs_of_digestion.html
Digestive Processes
I. Ingestion
a. Takes food in – mouth
II. Peristalsisa. Muscular contractions along digestive
tract-esophagus small and large intestine
III. Absorption
a. Taking of digested food into blood stream
b. Occurs in Sm. Intestine
IV. Storage
a. Animal “starch” stored as glycogen in liver
V. Elimination
a. Solid waste eliminated from large intestine
VI. Mechanical Digestion
a. Physically chewing-mouth
b. Churning action-stomach
VII. Chemical Digestion
a. Uses enzymes
b. Starts carbohydrate breakdown in mouth
c. Starts protein breakdown in stomach
d. Carbohydrates, proteins, and fats are fully digested in Sm. Intestine
Types of Food
Food Type % Diet Purpose Digestive End Product
Fats <30% Store energy Glycerol + 3 Absorb Vitamins fatty acids
Protect organs
Carbohydrates 55% Energy source monosaccharides Absorption of food glucose
Fiber
Proteins >15% Growth Amino Acids
maintenance/repair
makes enzymes
What happens to the Digestive End Product (listed above):
Absorbed into blood and delivered to cells and organs
For Fats used or stored For Carbohydrates used for energy or stored For Proteins used to rebuild/enzymes Remember organisms are very efficiently adapted to
providing the nutrients they need. The complex process of changing one type of macromolecule into another is very complex with any one able to change into the other, through many steps and much energy input.
To speed Digestion organisms use chemicals and enzymes
Acids Gastric acid in stomach Contains HCl
Bile Secreted by liver-stored in gall bladder Emulsifies fats (dissolves-NOT digest)
Enzymes – each enzyme (made of protein) is regulated, with a special “job”
Jobs include Operate by “Lock and Key” approach Some examples Hydrolysis – (Breaking down polysaccharides to create
simple sugars)
Enzymes are:
1. Highly specific
2. Can speed up the same chemical reaction in either direction.
3. NOT used up in the reaction.
Lipase is an enzymethat digests fat.
Bile is a solutionthat emulsifies fats.
Together, they speedup the breakdownof fats in the digestivesystem.
Enzymes in Plants
Remember, Autotrophs make their own organic nutrients (simple sugars). How do plants do this?
Enzymes speed the necessary chemical reactions and give organisms the ability to control how much, where, and when these reactions occur Glucose is coupled together into starch in the roots of plants for storage.
The enzyme for this reaction is called: Sucrase The chemical reaction that occurs is a
Dehydration Synthesis, draw the structures of two glucose molecules being joined to create a disaccharide.
How do they work?
Enzymes function by binding to one or more of the reactants (substrate) in a reaction.
The exact location on the enzyme where substrate binding takes place is called the active site of the enzyme.
The shape of the active site just fits the shape of the substrate, somewhat like a lock fits a key.
In this way only the correct substrate binds to the enzyme
http://www.efhealing.com/images/enzymes.jpg
Types of Enzymes
Enzyme Made Here Acts Purpose
Amylase Mouth & Mouth & breaks polysacs to
Pancreas Sm. Intestine disacs (digests carbs)
Pepsin Gastric glands Stomach Starts digestion
of stomach
Rennin Stomach Stomach Coagulates (thickens)
protein in milk
Lipase Pancreas Sm. Intestine Reduces fats to fatty
acids and glycerol
(building blocks of fats)
Enzymatic Digestion of food types (Macromolecules)
Name the chemical process used by these enzymes to help digest fats, carbohydrates, and proteins:
Use diagrams of Macromolecules to fill in the chart below. Use circled numbers to indicate locations of hydrolysis
http://www.whfoods.com/genpage.php?tname=faq&dbid=16#digestion
Hydrolysis
Digestive Problems:
Lactose Intolerence -
Inability to digest milk sugar (enzyme lactase)
Appendicitis -
Bacteria gets in appendix and causes flu like symptoms and eventually shooting pain in right side. Surgically removed.
Tape worms
Parasite that stays in your intestines and absorbs all the nutrients. Get it from undercooked meat.
Diabetes
Cannot produce insulin in pancreas
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