Grade 10 IB Science: Digestive Systems

What are the four stages of Digestion

Ingestion, Digestion, Absorption, Egestion

What happens in Ingestion

Taking in of nutrients

What happens in Digestion

Breakdown complex nutrients into simpler components

What happens in Absorption

Transport of digested nutrients to the tissues of the body..

What happens in Egestion

Removal of wastes from the body

What does the Mouth and Teeth do?

Teeth bite food into a soft pulp that is easy to swallow. Chewing mixes the food with watery saliva. A form of Mechanical digestion

How many salivary glands around the mouth and face do we have?

6

Tongue

Forms food into a bolus

What does the Hard Palate do?

Contains food, important for sound

What does the soft Palate do?

Muscle holding uvula

Uvula

Blocks the nasal Passage when swallowing

Molars

Teeth-grinding

Canine

Teeth-shredding

Incisors

Teeth-blade-like

How does the mouth and teeth break down the food? (Part 1) (Step 1)

Salivary glands release saliva (amylase) - molecule that breaks down starch into simple sugars. A type of chemical digestion

How does the mouth and teeth break down the food? (Part 2) (Step 1)

Bolus passes through the pharynx into the esophagus.

How does the mouth and teeth break down the food? (Part 3) (Step 1)

The bolus is prevented from entering the trachea by the epiglottis

What is the Esophagus?

Esophagus is a muscular tube.

What is the process of the Esophagus? (Step 2)

Takes food from the throat and pushes it down into the stomach. It moves food by waves of muscle contraction called peristalsis - a wave of contraction and relaxation. Gravity is not necessary for this process to occur.

What is the Stomach?

Has thick muscles that contract to mash the food into a soup called chyme. Both chemical and mechanical.

What does the Stomach do?

The stomach lining produces strong digestive juices to breaking down and emulsifies foods. Do not absorb anything, just helps break it down.

What is the process of the Stomach? (Part 1) (Step 3)

Two valves control the entrances of food into and out of the stomach.

What is the process of the Stomach? (Part 2) (Step 3)

Pyloric Sphincter- opening to the small intestine.

What is the process of the Stomach? (Part 3) (Step 3)

Esophageal Sphincter- opening esophagus and stomach.

What is the Small Intestine? (Part 1)

Very long - about 20 feet

What is the Small Intestine? (Part 2)

More enzymes (like amylase, break down macromolecules).

What is the Small Intestine? (Part 3)

Nutrients are small enough to pass through the lining of the small intestine, and into the blood.

What is the Small Intestine? (Part 4)

Absorption begins

How does the Small Intestine break down food? (Part 1) (Step 4)

The small intestine consists of finger-like projections called villi (singular villus), which increase the surface area of the small intestines.

How does the Small Intestine break down food? (Part 2) (Step 4)

Each villus is covered with microvilli to increase absorption.

What are the three consecutive sections? (Part 3) (Step 4)

Duodenum, Jejunum, Ileum,

What does the duodenum do?

Chime enters through pyloric sphincter receives secretions from pancreas and liver.

What does the jejunum do?

Performs most of digestion/absorption

What does the ileum do?

Last part of the small intestine before large intestine.

How many functions does the pancreas have?

2 main functions

What does the pancreas do? (Part 1) (Step 5)

Pancreatic juice containing enzymes to digest food in the intestine.

What does the pancreas do? (Part 2) (Step 5)

Produce hormones insulin and glucagon to regulate blood sugar.

What does the Liver do? (Part 1) (Step 6)

The liver secretes bile, which is essential for digestion.

What does the Liver do? (Part 2) (Step 6)

Bile is stored in the gall bladder and released into the small intestine via the common bile duct.

What does the Liver do? (Part 3) (Step 6)

Serves to detoxify blood of harmful substances like alcohol and nicotine.

What does the Gall Bladder do? (Part 1) (Step 7)

Bile is stored in the gall bladder and released into the small intestine.

What does the Gall Bladder do? (Part 2) (Step 7)

Aids the digestion of fats in the small intestine.

How many consecutive sections do the Large Intestines have?

Caecum, Colon, Rectum, Anus

What does the Caecum do?

pouch connected to large intestine - contains the appendix.

What does the Colon do?

absorbs water leaving more solid material which the body cannot use. Indigestible material is stored for before leaving body.

What does the Rectum do?

holds feces

What does the Anus do?

anal sphincter control excretion of waste.