Life Sciences Gr.11 Lesson 36 Gaseous exchange (Human gas exchange, functions and adaptations of the ventilation system)

Life Sciences: Gaseous Exchange

  • Presenter: Dr. Grizelda van Wyk

  • Grade 11 Lesson 36

Functions of Gaseous Exchange System

  • Primary Function: To facilitate the exchange of gases necessary for human survival.

    • Inhalation: Oxygen is taken from the air into the lungs.

    • Alveoli Role: Oxygen-rich air reaches the alveoli where exchange occurs.

    • Diffusion: Oxygen diffuses into the bloodstream for transport to body cells.

    • Exhalation: Carbon dioxide produced from cellular respiration is expelled from the body.

Location of Gaseous Exchange

  • Two main sites for gas exchange:

    1. External Gaseous Exchange: Occurs in the alveoli.

    2. Internal Gaseous Exchange: Occurs between blood and body tissues.

Alveolar Structure and Function

  • Anatomy of Alveoli:

    • Air enters alveoli with high oxygen concentration.

    • Surrounding capillaries carry deoxygenated blood.

    • Major Components:

      • Bronchioles

      • Pulmonary venules (oxygenated blood)

      • Pulmonary arterioles (deoxygenated blood)

Gaseous Exchange in Alveoli

  • Oxygen Concentration: Inhaled air has a higher oxygen concentration than blood in capillaries.

  • Carbon Dioxide Concentration: Inhaled air has a lower carbon dioxide concentration compared to blood.

  • Process:

    • Oxygen diffuses into blood.

    • Carbon dioxide diffuses from blood into alveoli for exhalation.

Gaseous Exchange at Cellular Level

  • Carbon Dioxide Release: Cells produce high carbon dioxide due to respiration.

  • Diffusion: Carbon dioxide diffuses from cells into blood for transport back to lungs.

  • Transport Mechanism:

    • Majority carried as bicarbonate ions in blood plasma.

    • Transported to heart and then to lungs for exhalation.

Oxygen Transport in the Blood

  • Main Transport Method: Oxygen primarily carried by red blood cells via hemoglobin.

  • Forms Oxyhemoglobin for effective transport to body cells.

Summary of Gaseous Exchange and Transport

  • Continuous oxygen intake at alveoli surface.

  • Carbon dioxide transport from cells back to alveoli for removal from the body.

Activities

Activity 1

  1. Identify epithelial tissue labeled 1 and 2:

    • Type 1: Thin squamous epithelium

    • Type 2: Erythrocytes (red blood cell)

  2. Pigment in red blood cells: Hemoglobin

  3. Blood types at capillary:

    • At A: Deoxygenated blood

    • At B: Oxygenated blood

Activity 2

  1. Oxygen form in blood: Oxyhemoglobin

  2. Structural adaptations of alveoli:

    • Rounded shape increases surface area for gaseous exchange.

    • Thin lining facilitates rapid diffusion of gases.

    • Richly supplied with blood capillaries for efficient transport.

    • Moist surface aids gases entering in dissolved form.

Activity 3

  • Carbon Dioxide Exchange:

    • High carbon dioxide concentration in cells from respiration.

    • Diffusion into blood.

    • Transported mainly as bicarbonate ions.

    • Returned to heart, then exhaled from lungs.

Activity 4

  • Gaseous Exchange Process:

    • High oxygen concentration in inhaled air compared to surrounding blood.

    • Oxygen diffusion into blood and carbon dioxide from blood to alveoli for exhalation.