SCI/P/4: EXCRETION

This Unit is about Excretion for example the skin, Teeth among others.

EXCRETION

THE SKIN

  1. It is found on the body surface
  2. It has pores (small openings) on it.
  3. It has hair on it

Uses of the skin to people

  1. Protects the body against external injuries.
  2. Protects the body against germs.
  3. Used in the making of Vitamin D.
  4. The skin regulates body temperature.

Care for the skin:

  • Bathing daily to remove germs.
  • Do not play rough games that can lead to injury on the skin.
  • Put on clean clothes
  • Avoid sharing clothes with infected people.

Diseases of the skin:

  1. Scabies
  2. Ring worm
  3. Herpes-zoster
  4. Athletes foot.

WATCH THE VIDEO BELOW TO LEARN ABOUT THE PART OF SKIN

HUMAN TEETH

  1. Set of teeth
  2. permanent teeth
  3. milk teeth
  4. incisors
  5. canine molars(wisdom teeth)

A tooth is a hard bone-like structure in vertebrates used for breaking food into smaller pieces.

Sets of teeth.

  1. Milk teeth (deciduous teeth)
  2. Permanent teeth.
This structure of the Teeth shows the different types of Teeth, the age they grow and the age bracket they are lost.

N.B: There are 20 milk teeth.

Milk teeth start growing the age of 6 months and at the age of around 7 years, these teeth begin to fall out and are replace by permanent teeth.

Permanent teeth

  1. This is the second and final set of teeth in mammal’s growth.
  2. They are the ones that replace the milk teeth.
  3. A person starts developing permanent teeth at 13 years.
  4. An adult normal person has 32 permanent teeth consisting of incisors, canines, premolars and molars.

Types of teeth

  1. Incisors
  2. Canines
  3. Molars (wisdom teeth)

Diagram showing the structure of the teeth

 

 

 

 

 

 

TYPES OF TEETH

INCISORS

  1. They are used for cutting and biting food
  2. They are chisel shaped.

AN INCISOR TOOTH                                                                                                  

  THE INTERNAL  PARTS OF AN INCISOR  TOOTH

incisor

  CANINES

  1. They are used for tearing food.
  2. They are sharp cone-shaped.

PREMOLARS

  1. They are used for grinding food.
  2. They are broad, blunt and flat ridged.

premolar

MOLARS

  1. They are used for grinding and chewing food.
  2. They are broad, blunt and flat ridged.

jaws

N.B: Dental formula is the arrangement of teeth in the jaws.

THE INTERNAL PARTS OF A TOOTH

The InfoVisual.info site uses images to explain objects.
The InfoVisual.info site uses images to explain objects.

FUNCTIONS OF PARTS OF A TOOTH

ENAMEL

  • The hardest part of the tooth.
  • It is the hardest substance in the body made up of calcium and phosphorus.
  • It prevents wear and tear of the tooth.

DENTINE

  1. It keeps replacing the enamel as it may wear off due to friction.

PULP CAVITY

  1. It is the most sensitive part of the tooth.
  2. It has the blood vessels and sensory nerves.

BLOOD VESSELS

They carry digested food and oxygen to the tooth.

THE SENSORY NERVES

  1. They are sensitive to heat, pain and cold.
  2. The tooth begins paining when bacteria destroys the pulp cavity.

CEMENT

It fixes the tooth into the jaw bone.

THE GUM

It gives extra support to the tooth in the jaw bone.

JAW BONE

  1. It holds the tooth in position
  2. It protects the tooth.

THE VIDEO BELOW SHOWS THE STRUCTURE OF A TOOTH AND THEIR FUNCTIONS

DISEASES OF THE TEETH

  • Tooth decay (dental carries)
  • It is caused by bacteria.
  • Bacteria acts on sugar and starch, remains on the teeth producing lactic acid that wears and tears the enamel and makes a hole in the dentine and pulp cavity.
  • Pain begins when bacteria destroys the pulp cavity.

NB: Dental amalgam (cement) can be used to fill the holes made on the teeth.

Periodental disease (Gum disease) – This affects the gum.

Disorders of teeth

  • Impacted teeth.
  • Broken teeth
  • Tooth cracks

Disorders of the mouth

  1. Thrush
  2. Cancer
  3. Burning tongue

CARE OF OUR TEETH (DENTAL HYGIENE)

  • Brush the teeth after every meal.
  • Avoid drinking very hot and cold things.
  • Avoid eating too many sweets.
  • Rinse your mouth with water and salt after every meal.
  • Eat plenty of fresh fruits and vegetables.
  • Visit a dentist regularly for checkups.
  • Eat a balanced diet.

Things we use for brushing teeth.

  1. Tooth brush
  2. Tooth paste
  3. Clean water
  4. Small sticks

How to brush our teeth

  1. Brushing teeth should be up and down movement of the tooth brush but not sideways.
  2. Then clean tooth brush and keep it in a container.

N.B: We brush our teeth regularly to;

  • Prevent tooth decay
  • Prevent bad breath

VIDEO TO SHOW HOW TO TAKE CARE OF YOUR TEETH

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