Respiration in Humans

• The structure of the alveoli allows for efficient gas exchange in humans
• The respiratory system comprises various organs that facilitate gaseous exchange
• Living organisms rely on respiration to release energy from the breakdown of carbohydrates
• Energy is needed to carry out processes to sustain life
• In the human respiratory system, key parts include the larynx, trachea, bronchi, bronchioles, alveoli, and associated capillaries
• The alveoli's structure is suited for gaseous exchange
• Major toxic components of tobacco smoke are nicotine, tar, and carbon monoxide, with harmful effects on health
• Aerobic respiration in human cells releases energy by breaking down glucose in the presence of oxygen, while anaerobic respiration releases energy in the absence of oxygen
• During vigorous exercise, cells respire anaerobically, leading to an oxygen debt that is removed by rapid, deep breathing after exercise
• Muscle cells respire aerobically at a high rate during vigorous muscular contractions
• Anaerobic respiration occurs in muscle cells to meet increased energy demand during vigorous activity, leading to the formation of lactic acid
• Oxygen debt, or lactic acid, is removed after exercise through continued fast heart rate and deeper breathing
• Respiration in humans is similar to other organisms, with plants, small animals, and microorganisms used in experiments to investigate respiration
• Oxygen debt is the amount of oxygen required to remove lactic acid
• Carbon dioxide is given off during aerobic respiration and fermentation (anaerobic respiration)
• A hydrogencarbonate indicator can detect changes in carbon dioxide concentration
• The larynx, trachea, bronchi, bronchioles, alveoli, and associated capillaries play vital roles in human gaseous exchange
• The trachea is supported by C-shaped rings of cartilage
• The structure of an alveolus is suited for its function of gaseous exchange through adaptations like:

  • One-cell thick alveolar walls
  • Layer of moisture in alveolar walls
  • Close contact to capillary network
  • Numerous alveoli
• Gas exchange in the lungs occurs by diffusion, with oxygen dissolving into the film of moisture on the wall of the alveolus and then diffusing through the wall of the alveolus and the wall of the blood capillary into the red blood cells
• The oxygen and carbon dioxide concentration gradient between the alveolar air and the blood are maintained by a continuous flow of blood through the blood capillaries and continuous breathing, which causes air in the lungs to be constantly refreshed
• Inspired air differs from expired air in terms of oxygen and carbon dioxide levels, with inspired air having higher oxygen and lower carbon dioxide levels compared to expired air
• Tobacco smoke contains harmful chemicals like nicotine, tar, and carbon monoxide, which have various negative effects on health including increased heart rate, blood pressure, risk of cancer, and reduced oxygen transport capacity in the blood