Unit 11Digestive System

•4 functions of the
digestive system:
•1. Ingestion- taking in
food

•2. Propulsion-
movement of food

•3. Digestion &
absorption- breaking
down food & taking in
nutrients

•4. Egestion- elimination
of waste

1. Alimentary canal
(gastrointestinal tract)
• mouth
• pharynx
• esophagus
• stomach
• small intestine
• large intestine

2. Accessory organs
• teeth
• tongue
• salivary glands
• liver
• gall bladder
• pancreas

•All areas of the alimentary canal contain a
four-layer arrangement of tissues:

Mucosa

Submucosa

Contains glands, nerve fibers and blood vessels

-functions:

1. secreting mucus, digestive enzymes, & hormones
2. absorption of nutrients
3. protection from pathogens (lymphatic tissue)

Serosa
(visceral peritoneum)
-membrane that secretes a slippery, watery fluid
-reduces friction as digestive organs contract and move

Muscularis
Layer of muscle extending in two directions:

-circular layer
-longitudinal layer

•Teeth are accessory digestive organs.

•They are responsible for beginning the
mechanical digestion process

Incisors: Used for cutting
pieces of food

Canines (cuspids): tear
and pierce

Premolars (bicuspids):
used for crushing

Molars (tricuspids):
used for grinding

Enamel: hard, protects tooth

Dentin: calcified connective tissue

Pulp cavity: contains blood vessels and nerves
Gingivae (gum): provides seal around tooth

Cementum- covers the dentin in the root

Bone of jaw

artery

vein

•The digestive system has multiple
functions and is generally divided
into 2 portions: the alimentary
canal and the accessoryorgans.
Teeth begin the process of
mechanical digestion by tearing
and grinding food.

Multiple Select

What are some function of the digestive system?

• Ingestion

• Egestion

• Enzyme release

• Propulsion

• release gastric juices

Multiple Choice

What are the two types of digestive systems?

• Mechanical and Chemical
• Physical and Biological
• Simple and Complex
• Fast and Slow

Categorize

Options (12)

mouth

pharynx

esophagus

stomach

small intestine

large intestine

teeth

tongue

salivary glands

liver

gall bladder

pancreas

Organize these options into the right categories

Alimentary canal

Accessory organs

Match

Match the following

• Incisors

• Canines

• Premolars

• Molars

Chewing and Cutting

Tearing and Holding

Crushing and Grinding

Grinding and Crushing

• Chewing and Cutting

• Tearing and Holding

• Crushing and Grinding

• Grinding and Crushing

Reorder

Reorder the following from superficial to deep

• sercosa

• muscularis

• submucosa

• mucosa

1

2

3

4

• 1
• 2
• 3
• 4

Toddlers have only 20
teeth, compared to an
adult’s 32.
The incisors come in
first (6-8 months)
followed by the canines
and molars.
Even after these teeth
are replaced with
permanent teeth,
molars come in during
teens and early
twenties.

•Salivary glands produce
saliva:

•99% water

•Mucus (lubricates food for
swallowing)

•Amylase (breaks down starch)

•Lysozymes (kills bacteria)

•Antibodies (mark foreign
invaders)

•Hard palate: forms the bony roof of the mouth

•Soft palate: forms the rest of the mouth

•Uvula: prevents swallowed food from entering the
nasal cavity

•Tongue: helps to push food down towards the
esophagus

•Deglutition
(swallowing) has
2 major phases:
•1. The buccal
phase

•2. The
pharyngeal-esopha
geal phase

•The buccal phase:

•After chewing
(mastication) and
being mixed with
saliva, the food lump
is called a bolus.

•It is forced into the
pharynx by the
tongue.

•This is a
consciously-controlle
d process.

•The
pharyngeal-esophage
al phase:
•A thin flap of skin
called the epiglottis
blocks the larynx
and the uvula blocks
the nasal cavity.

•This causes food to
travel to your
esophagus instead
of into your
respiratory system.

•The bolus is propelled down the
esophagus using waves of muscle
contractions.

•This process is called peristalsis.

•Peristalsis is involuntary and caused by the
parasympathetic nervous system rather
than gravity.

•Mastication forms a bolus in the
mouth, which is swallowed. After
deglutition, the bolus moves past
the epiglottis and down the
esophagus by involuntary
contractions called peristalsis.

Multiple Choice

What is peristalsis?

• Involuntary muscle contractions in the intestines
• Voluntary muscle contractions in the intestines
• Involuntary muscle contractions in the stomach
• A type of bone structure

Multiple Choice

What is deglutition?

• Swallowing
• Digestion
• Breathing
• Chewing

Open Ended

How do child's teeth differ from adult teeth?

Multiple Choice

Saliva contains

• Enzymes, antibodies, and mucus
• Hormones, vitamins, and minerals
• Proteins, carbohydrates, and fats
• Water, salt, and sugar