THE DIGESTIVE SYSTEM
BIO 12
12.1 THE DIGESTIVE TRACT p. 214
NAME_________
A/ DIGESTION:
- give 4 functions of the digestive system:
1.
2.
3.
4.
- during digestion, two main processes occur simultaneously. They are
mechanical and chemical digestion. Describe what occurs during each:
-mechanical digestion:
-chemical digestion:
B/ THE DIGESTIVE TRACT:
- refer to the diagram on page 214. Label the blank diagram below:
THE MOUTH:
- give two functions of the tongue:
1.
2.
-
The roof of the mouth separates the oral cavity from the nasal cavities and
consists of two parts, the hard palate and the soft palate. Give the difference
between each in terms their structure and location in the mouth:
-
Examine fig. 12.2: Where is the uvula located?
-
Give the location and function of the tonsils.
-
Give the location of the three pairs of salivary glands
-
In addition to providing lubrication for food to be swallowed, saliva contains
water and an enzyme called salivary amylase (or ptyalin). Give the function
of this enzyme:
-
Give the function of teeth as they relate to the function of mechanical digestion in
the mouth:
THE PHARYNX:
- After food has been chewed and mixed with saliva, it is now in the form of a
small ball that is ready to be swallowed. This mass is called a bolus. This bolus now
passes into the pharynx. Give two things that this region normally
receives:
1.
2.
- Before swallowing can properly take place, two things must happen. Describe
each in detail:
-
explain why swallowing is often referred to as a reflex action:
THE ESOPHAGUS:
- give the function of the esophagus:
-
the bolus moves along the esophagus by a process called peristalsis. describe this
process:
-
At the base of the esophagus, the bolus encounters a constriction or cardiac
sphincter. Give the purpose of this sphincter:
THE STOMACH:
- give the shape and approximate capacity of the stomach:
-
list two things that the stomach does:
-
the lining of the stomach is filled with millions of gastric pits that lead to gastric
glands. These glands secrete a liquid called gastric juice. Name
three important components of gastric juice and give the function of each
component:
1.
2.
3.
-
After about 2-6 hours the stomach empties out and the food leaves the stomach in
the form of a runny, acid mixture called chyme. Chyme is released a little at a time
through a sphincter a the base of the stomach at the entrance to the small intestine
called the pyloric sphincter.
THE SMALL INTESTINE:
- the small intestine is actually about 6 meters in length compared to the 1.5 m
length of the large intestine. So, why is it still referred to as the “small” intestine?
-
name the region of the small intestine that makes up the first 25 cm of its
length.
-
this region is connected by ducts from two organs. Name each organ and
give the secretions given by each organ:
-
what is the function of pancreatic juice?
-
what is the function of bile?
-
Your text states that the small intestine has a total surface area that is about
equivalent to a tennis court. Explain how a tube that is 6 m long could have such a
large surface area:
-
Name the finger-like projections that give the small intestine its huge surface
area:
-
In the space below, draw a single villus. Label the goblet cells, lacteal,
and blood capillaries:
-
give the primary function of the villi:
-
The two main parts of a villus are the blood capillaries and a lacteal. Which
type of nutrients are absorbed by each part?
-
after nutrients are absorbed by the villi, where do they go and how are they
transported?
HORMONES AND DIGESTIVE JUICES: p. 220
- read the first two paragraphs on page 220 and carefully examine figure 12.7.
Notice that the digestive juices (gastric juice, pancreatic juice and bile)
are controlled by three special hormones, CCK, Gastrin and Secretin.
Beside each hormone, give its source, and function:
Hormone
CCK
______ Source
Function
Gastrin
Secretin
THE LARGE INTESTINE:
- give 3 materials absorbed and 1 material stored by the large intestine:
-
name the small projection that lies at the blind end of the cecum:
-
suggest a possible function of this organ that is somewhat prone to
inflammation:
-
name the location and names of the 4 major parts of the colon:
- the last 20 cm of the large intestine is called the rectum which leads to the
anus where expulsion or defecation of feces occurs. Explain what occurs
during the defecation reflex. Examine figure 12.9 for help here:
-
feces are three quarters water and one quarter solid matter. List the
components of the solid portion of feces:
-
In addition to giving feces their distinctive odour and the production of gas,
give two benefits of bacteria such as E-coli in our large intestine