SBI3U – Anatomy
Date: ___________________
10.2 – The Human Digestive System: Part 1
Digestive Tract Organs (contains food)
Accessory Organs: (aid digestion)
Mouth
Salivary Glands
Esophagus
Liver
Stomach
Gallbladder
Duodenum
Pancreas
Jejunum
Ileum
Ascending colon
Transverse colon
Descending colon
Rectum
Anus
GASTROINTESTINAL TRACT (GI): (__________________________)  _________________ long approx.
6 Regions:
1. Oral cavity (mouth)
2. Pharynx (throat)
3. Esophagus
4. Stomach
5. Small Intestine
6. Large Intestine
1. Mouth/Oral Cavity

Mastication  _______________________

Smell or sight of food can trigger the _______________________________ to secrete saliva

SALIVA watery fluid that ____________________________, _______________________,
enables ______________ in mouth

Food + saliva = ____________________ (a small, round, soft mass of chewed food)

Initial digestion of carbohydrates begins in the mouth with the help of ______________ enzyme
(________________________________________)
2. Pharynx
 throat; _________________________________________
What is the role of the epiglottis?
_____________________________________________________________________________________
Figure 1: Pharynx
3. Esophagus

_________________________ through which food (bolus) passes from the mouth to the
stomach

Initiates _______________________  involuntary rhythmic _________________________
which moves food down GI tract

___________________________________  relaxes to allow _____________ to enter the
stomach; otherwise closed to prevent acid from entering esophagus
Figure of Peristalsis
4. Stomach

muscular, J-shaped, left side of the abdominal cavity, below the diaphragm

Stomach walls folded (accordion), allowing stomach to _____________ after a meal
Functions of the Stomach:
i.
_____________________________________________________________________
ii.
Stomach muscles _______________________________ to churn and mechanically break up
pieces of food and mix them with _____________________________.
iii.
Chemical breakdown of food using gastric juices (mucous + Hydrochloric acid – HCl,
enzymes)

mucous  ___________________________________

HCl  __________________________________________

Pepsin  _________________________________________________
Result of breakdown is __________________ (thick liquid of digested food with gastric juice)
4. _______________________________  controls flow of ______________ with contractions and
squeezes liquefied food particles into small intestine (duodenum)
Figure 3: Folds in the Stomach wall
5. Small Intestine
Digestion is completed in small intestine

Macromolecules are broken down and absorbed by intestinal cells and move into the
___________________________________

Small diameter (___________), however it is approx. __________________

Large Surface area (10x increase in SA due to villi)

Absorption of __________________________________________________________
Figure 4: Sections of the Small Intestine
Segments of the Small Intestine
1. duodenum  ___________________, first 25-30 cm of small intestine; most digestion occurs
here. As food passes through, it receives secretions from two organs:
_____________________________________
2. jejunum  ~ 2.5 m, continues breakdown of remaining __________________________;
specialized lining then absorbs these nutrients
3. ileum  ~ 3 m, absorbs remaining nutrients, pushes _______________________ material into
the large intestine
Absorption of Nutrients
 most absorption of nutrients takes place in small intestine
 The inner lining, is folded and covered with tiny finger-like projections called ___________  a
design that
________________________________________________________________________
 Each villi is covered with even tinier fingerlike projections called ___________________ which
cover the cell surfaces
Figure 5: Capillaries (tiny vessels) allow nutrients produced by digestion to travel to the cells of the body
6. Large Intestine
 __________ diameter; only ___________ long
 Manufacturing of vitamins

Uses waste material to synthesize vitamins such as ___________
 Absorbs water from the remaining indigestible food matter, and then useless waste material is
____________________
To DO: p. 414 #7 – 12
10.2 – The Human Digestive System: Part 2
Liver

____________ internal organ, ~1.5 kg

Main Functions:
o
Conversion of ____________________________________________, and vice versa
o
Processes nutrients and stores nutrients for release into bloodstream (i.e. glycogen,
vitamins, etc.)
o
__________________________ of harmful substances and excretes them via urine
(i.e. bacteria, old red blood cells)
o
____________________________  sent to gall bladder
Note: This organ has the ability to heal and regenerate itself
Gall Bladder

Pear-shaped, ~ 3 inches long

Bile made in the liver is __________________ in the gall bladder

Bile is released into small intestine for the digestion of lipids

Greenish-yellow fluid with bile salts

Bile emulsifies ________

Bile salts act like detergent, breaking fat into smaller fat droplets (__________________)

Fat droplets then chemically broken down by digestive enzymes (___________________)
Bile
Enzymes in the Pancreas

Pancreas fluid contains many enzymes that chemically breakdown _____________, _________,
and _______________ in the small intestine

Fluid also contains ________________________:
o
Very important role
o
Alters the pH of _________________ from strongly acidic (pH 1) to
___________________ (pH 8) in the duodenum so that enzymes can work efficiently
Factors Affecting Enzymes

__________________
o

Affects the rate at which an enzyme functions to break down complex molecules
______
o
Pepsin works in the acidic environment inside the stomach
o
most enzymes such as trypsin work in pH values of 6 – 8
See Table 10.5 on p.416
Large Intestine

Storage of ______________ materials

_________________ reaches colon undigested
o
dietary ___________ provides bulk
o
egestion is more frequent
o
bowel movements _______________________ from body
o
Less fibre = ____________________________ = more time for toxins to affect the colon
o
fibre reduces cholesterol levels
To Do: p. 417 #13 – 18
p. 419 # 1 – 16