g9 science

• Acids release hydrogen ions when dissolved in water, making them corrosive to metals such as iron.
• A neutral solution has a pH value of 7.
• Bases are substances that react with acids to form salts and water.
• The pH scale measures the acidity or alkalinity of solutions on a logarithmic scale from 0-14.
• A neutral substance has a pH value of 7, while an acidic substance has a lower pH value (less than 7) and an alkaline substance has a higher pH value (greater than 7).
• The pH scale measures the acidity or alkalinity of a solution.
• Respiratory system


  Also known as the human breathing system, responsible for taking in oxygen and expelling carbon dioxide
• Parts of the respiratory system

  • Nose and mouth
  • Nasal cavity or nasal passageways
  • Pharynx
  • Larynx
  • Trachea
  • Lungs
  • Bronchi
  • Bronchioles
  • Alveoli
• Inhalation


  1. Oxygen enters the body

  2. Ribs move out, chest space increases

  3. Diaphragm muscle contracts, moves down
• Exhalation


  1. Carbon dioxide exits the body

  2. Ribs move in, chest space decreases

  3. Diaphragm muscle relaxes, moves up
• Circulatory system


  Also known as the cardiovascular system, the life support structure that nourishes cells and delivers materials in the body
• Major parts of the circulatory system

  • Heart
  • Blood vessels (arteries, veins, capillaries)
  • Blood
• The heart is a hollow muscle as big as your fist
• Parts of the heart

  • Right atrium
  • Left atrium
  • Right ventricle
  • Left ventricle
  • Tricuspid valve
  • Bicuspid valve
  • Pulmonary valve
  • Aortic valve
  • Superior vena cava
  • Inferior vena cava
  • Pulmonary artery
  • Pulmonary vein
  • Aorta
• Circulatory system function


  Air enters lungs, goes to left side of heart, pumped through body, oxygen and nutrients delivered to cells, carbon dioxide returned to right side of heart, expelled through lungs
• Types of circulation


  • Pulmonary circulation
  • Coronary circulation
  • Systemic circulation
• The circulatory system functions with other body systems to deliver different materials in the body, circulating vital elements like oxygen and nutrients while also transporting waste away