Download The Digestive System

Student name: ______________________________ Block: _____ Date: _________
The Digestive System The process of breaking down the food we eat into small molecules that the body can
use is called ​
______________​
. Our bodies use these small molecules as
____________ and building blocks to form new cells and allow our bodies to function
and to __________. Digestion is carried out in the ​
Digestive System​
, and is helped
along by special proteins called ​
____________​
.
The Digestive System is essentially a single long ​
____________ that begins at your
mouth and ends at your anus. The tube changes shape and size as it goes along, and
different parts of the digestive process are carried out at different points along the
tube. The digestive system is full of trillions of ​
____________ that aid the process of
digestion, and use indigestible material to produce vitamins which our body uses.
Digestion happens in 4 stages:
Student name: ______________________________ Block: _____ Date: _________
-
Ingesting
-
Digesting
-
Absorbing
-
Eliminating
Stage 1: Ingesting Ingestion is the starting point of the digestive
process. ​
Ingestion occurs when food enters the
body through the mouth.
Stage 2: Digesting Mouth​
: Digestion begins in the mouth with
______________
and
chemical
digestion.
Mechanical digestion occurs when food is broken
down into pieces small enough to ____________
by the teeth and tongue. Food also reacts with an
___________ called amylase in saliva which
breaks down complex carbohydrates. The food is
formed into a ball called a _________.The bolus is covered by saliva, aiding
swallowing.
Esophagus​
: When swallowed, the bolus
moves past the epiglottis which directs it
into the ____________, a tube leading to
____________​
. The bolus is pushed down
the esophagus to the stomach by the
muscles in the esophagus in a process
called __________.
Stomach​
: In the stomach food is bathed in
gastric juices; hydrochloric acid, mucus,
and enzymes. Proteins in the food are
broken down by the enzyme pepsin and by
hydrochloric
acid,
while the stomach
contracts to mix the food up to aid
digestion. The stomach is lined with a
__________ that protects it from the acidic
gastric juices. The food, now a liquidy mix
Student name: ______________________________ Block: _____ Date: _________
called chyme, continues on to the next step.
Small intestine​
: Food enters the small intestine, a ​
_______ long, 2.5cm wide tube,
from the stomach. In the first meter of the small intestine, the digestion of food is
completed by enzymes and bile, which break down carbohydrates, protein and fats.
The enzymes are produced by an organ called the ___________, while bile comes
from the liver, and is stored in the gallbladder. Trillions of bacteria in the small
intestine also assist in the digestion of food and absorption of nutrients.
Stage 3: Absorption Small intestine​
: For the remaining 5 metres of the small intestine, nutrients are
absorbed from the food by tiny finger-like structures called ​
__________ lining the
Student name: ______________________________ Block: _____ Date: _________
inside of the intestine. The villi increase the surface area of of the small intestine by
500x, greatly speeding absorption.
Large intestine​
: The large intestine, a 1.5m long, 5cm wide tube, absorbs
__________ and _________ ​
from the food. By the time the food leaves the large
intestine, 90 percent of the water has been reabsorbed.
Stage 4: Elimination Any remaining undigested material, called feces, is now mixed with waste from the
body, such as dead red blood cells. Feces is stored in the rectum until it is expelled
through the anus in a process called elimination. The full digestive process from
ingestion to elimination takes about ​
____________​
hours.
Homework Problems​
​
(Answer in full sentences)
1. How many stages of digestion are there?
2. Describe the function of an enzyme and give an example.
3. What is a bolus?
4. Describe how a bolus is moved down the esophagus to the stomach.
5. What is the function of the mucus coating on the stomach wall?
6. Where are the enzymes in the small intestine produced, and what do they do?
7. How is the surface area of the small intestine increased?
8. What is the main function of the large intestine?
9. Describe the process of elimination in the digestive system.
10.Which organs and structures carry out digestion? Briefly mention the role of
each in digestion.