Continuation

• What is the main topic discussed in the video?

  Cell specialization
• Why are specific cells and concepts discussed in the video important for the HL curriculum?

  They are examples of how cells are differentiated and specialized for specific functions
• What must cells maintain to ensure homeostasis?

  A threshold of surface area to volume ratio
• What happens if the surface area to volume ratio drops too low?

  The cell becomes too large
• How do some cells adapt to increase their surface area to volume ratio?

  By containing specific adaptations that enhance their surface area
• What are the two examples of specialized cells mentioned in the video?

  • Red blood cells
  • Cells lining the proximal convoluted tubule of the kidney
• What is the primary function of red blood cells?

  To carry and transport nutrients
• How does the shape of red blood cells contribute to their function?

  The biconcave disc shape increases the surface area to volume ratio
• What is the role of the proximal convoluted tubule in the kidneys?

  To reabsorb useful nutrients from the filtrate back into the blood
• What adaptations do the cells lining the proximal convoluted tubule have?

  They have a layer that is one cell thick and specialized structures on their surfaces
• What are microvilli and where are they found?

  Microvilli are projections that increase surface area for absorption, found on the apical surface of proximal convoluted tubule cells
• What is the function of the surfactant produced by type 2 alveolar cells?

  To reduce surface tension in the alveoli
• What are the two types of cells that make up alveoli?

  Type 1 and type 2 alveolar cells
• How do type 1 alveolar cells facilitate gas exchange?

  They are wide and extremely thin, allowing for quick diffusion of gases
• What is the significance of intercalated discs in cardiac muscle cells?

  They allow for the propagation of electrical signals for coordinated contractions
• What are the differences between skeletal and cardiac muscle cells?

  • Skeletal muscle: long, voluntary, multiple nuclei
  • Cardiac muscle: shorter, involuntary, usually one nucleus, connected by intercalated discs
• What is the primary function of sperm cells?

  To fertilize egg cells
• How do egg cells differ from sperm cells in terms of movement?

  Egg cells are moved passively down the female reproductive tract
• What adaptation allows sperm cells to reach the egg for fertilization?

  The tail packed with mitochondria for movement
• What happens to the plasma membrane of an egg cell when a sperm cell enters?

  The chemical composition changes to prevent other sperm from entering
• What are the roles of sperm and egg cells in sexual reproduction?

  • Sperm: smaller, motile, delivers genetic material to the egg
  • Egg: larger, contains nutrients for the developing zygote