Body Systems

Cardiovascular & Circulatory System

  • Primary function: transports nutrients to and waste products from cells.
  • Consists of the heart, blood, and blood vessels.
  • Nutrients travel via the hepatic portal vein to the liver, then to the heart via the inferior vena cava.
  • The heart pumps nutrient-rich blood to the lungs for oxygen, then to the body.
  • Arteries decrease in size to capillaries, slowing blood flow for nutrient and waste exchange.
  • Blood composition: 78% water, 22% solids.
  • Plasma: 95% water, contains proteins, ions, glucose, lipids, vitamins, minerals, waste products, gases, enzymes, and hormones.
  • Blood samples indicate overall health.

Central Nervous System

  • Brain contains over one hundred billion neurons.
  • The central nervous system includes the brain, spinal cord, and nerve bundles.
  • Primary function: senses environmental changes and creates reactions.
  • Nerve impulses travel via movement of charged atoms (sodium, potassium, calcium, chloride).
  • Nerves communicate via neurotransmitters (chemicals built from amino acids).
  • Adequate protein intake ensures necessary amino acids for CNS.
  • Gut bacteria contribute to neurotransmitter and hormone production, influenced by diet.
  • The brain uses 20% of the body's fuel, primarily glucose.
  • Lipids are critical for CNS, cholesterol for myelin sheath, and omega-3 fatty acids for brain development and neuron activity.

Respiratory System

  • Humans can't survive without breathing for more than 3 minutes.
  • Cells require oxidative metabolism for ATP regeneration.
  • Oxygen is a reactant for oxidative phosphorylation, carbon dioxide is a waste product.
  • The accumulation of carbon dioxide primarily drives the need to breathe.
  • The respiratory system exhales carbon dioxide and inhales oxygen.
  • Process involves muscles moving air, passageways, and gas exchange surfaces covered by capillaries.
  • The cardiovascular system transports gases between lungs and tissues.
  • Functions: provides oxygen, removes carbon dioxide, and maintains acid-base balance.
  • Non-vital functions: sensing odors and producing speech.
  • Lungs perform gas exchange via pulmonary circulation.
  • Blood delivers oxygen and picks up carbon dioxide.
  • The pulmonary artery carries deoxygenated blood to the lungs.
  • Alveoli release carbon dioxide, and the lungs exhale it and take up oxygen.
  • Oxygenated blood drains via pulmonary veins to the body.