Mammalian Gas Exchange Revision Carousel Flashcards
Define the term diffusion.
Net movement of a substance from an area of high concentration to an areas of low concentration
-Passive
-Doesn’t require ATP
Define the term facilitated diffusion.
Movement of molecules from a high concentration to a low concentration across a partially permeable membrane via specific channel or carrier proteins
-passive
-Doesn’t require ATP
What is a channel protein?
A protein which created a fluid filled pore in the cell membrane through which ions and small polar molecules can pass
What is a carrier protein?
A protein which changes shape to allow larger molecules to pass through the membrane.
-In FD-requires no energy
-IN AT-requires ATP
What types of molecule can diffuse directly across the phospholipid bilayer?
-Small molecules such as oxygen and carbon dioxide
-Lipid soluble molecules such as steroid hormones and alcohol
State 3 main factors that affect the need for an exchange system.
SA:V ratio
Size
Level of Activity
Explain why smaller organisms have a lower demand for oxygen than larger organisms.
-Smaller organisms have a larger SA:V ratio than larger organisms
-Simple diffusion can be sufficient for unicellular organisms but due to many-layered multicellular organisms it would be too slow
-Multicellular organisms therefore need transport systems
Describe and explain 3 features of a good exchange surface/
-Large SA by folded walls providing more space for molecules to pass through
-Thin, permeable barrier to reduce diffusion distance
-Good blood supply keeping high concentration gradients for rapid diffusion
Describe how human alveoli are adapted to reduce diffusion distances.
-Alveolus and capillary wall are one cell thick and contain squamous flattened cells
-Capillaries are in close contact with alveoli walls
-Capillaries are narrow to restrict RBC movement
Describe the role of surfactant in alveoli.
Coats the internal surface of the alveoli to reduce cohesive forces between water molecules, preventing collapse
Why do alveolar walls contain elastic fibres?
To stretch during inspiration and recoil, pushing air out, during expiration
Which tissue type comprises alveolar walls?
Squamous Epithelium
The trachea is lined with ciliated epithelial tissue and goblet cells. Describe the functions of these.
GC-produce mucus onto tracheal lining, trapping dust and microorganisms
Cilia-beat and move the mucus away from lungs and towards throat
The trachea and bronchi are lined with cartilage. Describe why.
-C-shaped rings of cartilage line the tubes which prevents collapse during inspiration.
-C shape allows food to pass down oesophagus behind trachea
Describe how the nasal cavity is adapted for exchange.
-Large SA with good blood supply, warming air to body temperature
-Line with hair to secrete mucus to trap dust and MO’s, protecting from infections
-Moist surfaces to increase the humidity of the incoming air, reducing evaporation from exchange surfaces
