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General Biology: Human and Animal Respiratory Systems

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  • What are the three main phases of gas exchange in humans?

    Ventilation (breathing air in and out), external respiration (oxygen and carbon dioxide exchange between lungs and blood), and internal respiration (gas exchange between blood and body tissues).

  • Name four types of respiratory surfaces and the animals that use them.

    Diffusion (simple organisms), gills (fish and aquatic animals), tracheal system (insects), and lungs (amphibians, reptiles, mammals).

  • How does oxygen availability in air compare to cold and warm fresh and salt water?

    Air contains more oxygen than water. Cold water holds more oxygen than warm water. Freshwater holds more oxygen than saltwater.

  • How do fish gills maximize oxygen exchange?

    Gills have thin filaments with many lamellae providing a large surface area and use countercurrent flow to maximize oxygen diffusion into blood.

  • Why is breathing air easier than breathing water?

    Air has higher oxygen concentration and is less dense and viscous than water, requiring less energy to move over respiratory surfaces.

  • Describe the tracheal system of insects.

    A network of air tubes (tracheae) that deliver oxygen directly to tissues without using blood for transport.

  • Why do flying insects need to ventilate their tracheal systems?

    Flying increases oxygen demand, so insects actively ventilate to increase airflow and meet metabolic needs.

  • What respiratory adaptations did the fossil animal Tiktaalik have?

    Tiktaalik had both gills and lungs, showing adaptations for breathing in water and air during the transition to land.

  • What is the path of air in the human respiratory system?

    Air passes through the nose/mouth → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.

  • What are the main structures of the respiratory system and their functions?

    Nose/mouth: air entry; pharynx/larynx: air passage and voice; trachea/bronchi: air tubes; alveoli: gas exchange sites.

  • Why do alveoli need surfactants?

    Surfactants reduce surface tension in alveoli, preventing collapse and aiding lung expansion during breathing.

  • How is vertebrate metabolic rate related to its respiratory system?

    Higher metabolic rates require more efficient respiratory systems to supply oxygen and remove carbon dioxide.

  • Describe the structures and functions of the mammalian respiratory system.

    Includes nose, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli; functions to conduct air and exchange gases.

  • What is the impact of smoking on human health?

    Smoking damages respiratory tissues, reduces lung function, increases risk of diseases like cancer and emphysema.

  • How does negative pressure breathing work in humans?

    Diaphragm and rib muscles expand the chest cavity, lowering pressure inside lungs and drawing air in.

  • What part of the brain controls breathing and what gas does it monitor?

    The medulla oblongata controls breathing by monitoring carbon dioxide levels in the blood.

  • How does blood transport gases between lungs and tissues?

    Oxygen binds to hemoglobin in red blood cells for transport; carbon dioxide is carried dissolved, as bicarbonate, or bound to hemoglobin.

  • What are the functions of hemoglobin?

    Hemoglobin binds oxygen in the lungs, transports it to tissues, and helps carry carbon dioxide back to the lungs.