Human Biology Basics

Heart Structure

• The heart is a muscular organ that pumps blood throughout the body
• It is divided into four chambers:
  • Right atrium (upper right chamber) receives oxygen-depleted blood from the body
  • Right ventricle (lower right chamber) pumps blood to the lungs to pick up oxygen
  • Left atrium (upper left chamber) receives oxygen-rich blood from the lungs
  • Left ventricle (lower left chamber) pumps blood to the rest of the body
• The heart has four valves that ensure blood flows in one direction:
  • Tricuspid valve (between right atrium and ventricle)
  • Pulmonary valve (between right ventricle and lungs)
  • Mitral valve (between left atrium and ventricle)
  • Aortic valve (between left ventricle and aorta)

Blood Types

• There are four main blood types, determined by the presence or absence of specific antigens on the surface of red blood cells:
  • A (has A antigen)
  • B (has B antigen)
  • AB (has both A and B antigens)
  • O (has neither A nor B antigen)
• The Rh factor is another antigen that can be present or absent, resulting in:
  • Rh-positive (has the antigen)
  • Rh-negative (does not have the antigen)
• Blood type is inherited from parents and determines compatibility for transfusions

Vision Physiology

• The eye is a complex sensory organ that detects light and transmits signals to the brain
• Light enters the eye through the cornea, pupil, and lens, and is focused onto the retina
• The retina contains specialized cells called photoreceptors (rods and cones) that convert light into electrical signals
• The optic nerve transmits these signals to the brain, where they are interpreted as visual information
• The eye has a blind spot, where the optic nerve meets the retina, with no photoreceptors

Digestive System

• The digestive system is responsible for breaking down food into nutrients that can be absorbed and utilized by the body
• The process of digestion involves:
  • Mechanical breakdown (chewing, grinding) in the mouth and stomach
  • Chemical breakdown (enzymes) in the mouth, stomach, and small intestine
  • Absorption of nutrients in the small intestine
  • Elimination of waste in the large intestine
• The digestive system includes:
  • Mouth (teeth, tongue, saliva)
  • Esophagus (food tube)
  • Stomach (gastric acid and enzymes)
  • Small intestine (absorption of nutrients)
  • Large intestine (water absorption, storage, and elimination)

Test your knowledge of human biology fundamentals, including the heart's structure and function, blood types, vision physiology, and the digestive system. Understand how the body's systems work together to maintain overall health.