Download Digestive System Powerpoint

Digestive System
Purpose
• The digestive system is the organ system that
breaks down food into carbohydrates,
proteins, fats, vitamins, and nutrients for the
body to use for energy
Nutrients
• A nutrient is a substance that the body breaks
down and uses to grow, repair, and function
6 Processes of Digestion
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Ingestion
Secretion
Mixing & Movement
Digestion
Absorption
Excretion
Alimentary Canal
• Also called the Gastrointestinal (GI) Tract
• A long, hollow, twisted, and coiled tube that
runs through the body
• It includes:
• Mouth, throat, esophagus
• Stomach, small intestine, large intestine,
rectum, anus
1. Ingestion
• Food enters the digestive system through the
mouth
• eating
2. Secretion
• Process by which a substance is released from
an organ or gland to assist in digestion
• The body secretes almost 2 gallons of
digestive fluids per day!
– Saliva
– Mucus
– Hydrochloric acid
– Bile
Saliva:
• produced by salivary glands
• Watery mixture with digestive enzymes
– Enzymes speed up a reaction
• Speeds up the break down of food into
simpler substances
• Moistens food
Hydrochloric acid
• strong acid that breaks food down in the
stomach
Mucus
• Lubricant: helps food to slide down esophagus
easily
• Protection: mucus lines
the stomach walls to
protect it from the strong
acid inside
• Produced by liver Bile
• Stored in gallbladder
• Released into the
small intestine
• Thick green fluid
• Breaks down large
fat droplets in the
small intestine
3. Mixing & Movement
• Mixing begins with
the chewing muscles
in the mouth
• Tongue(large muscle) helps to form the bolus:
soft, round mass of chewed food
3. Mixing & Movement (cont)
• The tongue helps to move the
food into the pharynx
• Movement continues as the food
moves through the digestive tract
3. Mixing & Movement (cont)
• Most of the mixing happens in the stomach
• Food is mixed with gastric juice
– Gastric juice is a mixture of mucus, hydrochloric
acid and enzymes, especially pepsin
Protease
• A protease is an enzyme that breaks down
proteins
• Pepsin is a protease in gastric juice
4. Digestion
• Digestion is the actual breaking down of
complex food into basic building blocks
2 types of Digestion
A)Chemical digestion: the breakdown of food by
chemical means through enzymes
• It happens in
– The mouth (saliva)
– Stomach( protease & hydrochloric acid)
– Small intestine (enzymes from pancreas and bile
from gallbladder)
– Large intestine (gut flora)
Gut Flora
• Symbiotic bacteria that break down some
materials
2 types of Digestion (cont)
• B) Mechanical Digestion: the physical breaking
down of food.
• It involves: chewing, churning,
& segmentation
5) Absorption
• This is the process by which substances are
passed from the digestive tract into the blood.
• The blood transports them to other parts of
the body
• Mostly occurs in the small
intestine
• Nutrients are absorbed into
capillaries
6)Excretion
• This is the removal of waste products
• Digestive waste products
accumulate in the large intestine
• Remaining water is absorbed
• Solid wastes (feces) are
stored in the rectum and
eliminated through anus.
Organ Systems related to Digestion
• 1) Nervous System: prepares for food by
contracting stomach or triggering salivary
glands
Organ Systems related to Digestion
(cont)
• 2)Endocrine System: releases hormones that
regulate body functions.
• Some of these hormones determine
production of digestive juices, control
stomach muscle contractions, control
absorption rate of nutrients
The Mouth
• Both chemical and physical digestion takes
place in the mouth
• It contains the teeth, tongue, and salivary
glands
Teeth
• Adult jaw contains
32 teeth
• 4 types of teeth
Incisors
• 8 total (4 top, 4 bottom)
• Chisel shaped
• Biting large pieces.
Cuspids
• Also called canine teeth
• 2 upper, 2 lower
• Cone-shaped
• For grasping &
tearing food
Bicuspids
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Also called premolars
4 top, 4 bottom
Flat surfaces
For grinding food
Molars
• Similar to premolars, but larger
• 6 on bottom, 6 top
A tooth is made of….
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Enamel: hard tissue on outside of tooth
Crown: the part of tooth above gum
Root: part of tooth that anchors it into gum
Cementum: a thin, bony material that fixes
the root to the jaw
• Dentin: largest part of tooth, hard bone-like
tissue under enamel
Salivary Glands
• Three sets of glands
• Release saliva for chemical digestion
Tongue
• Tongue: primary organ of taste
• Taste buds: send taste information
to brain where it is processed
• Shapes food into the bolus and
directs it into the pharynx
Esophagus
• Movement of muscle contractions which push
the food is called peristalsis
Structure of the Stomach
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Hollow, muscular sac
Below the diagram, left side
Can expand to about 2 liters
Food remains in stomach for 1-2 hours
Muscle contractions cause the bolus to mix
with gastric juice
• Now the bolus is called chime.
Small Intestine
• Long, hollow, muscular tube
• Between 18-23 feet
• Length provides surface
area and time for the absorption
of nutrients.
Villi
• Small folds in the small intestine
• Contain artery, vein, and capillaries
• The capillaries absorb nutrients into the blood
Duodenum:
• entrance to small intestine from stomach
• This is where the bile and other enzymes from
pancreas an gallbladder
Large Intestine
• Has a larger diameter than small
intestine
• Less than 5 feet long
• Function: 1) to absorb any remaining water,
electrolytes, and vitamins in the colon
• 2) remove wastes through rectum and anus.
Liver
• 2nd largest organ
• Under right rib cage