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Gas exchange in humans Flashcards iGCSE Biology

Gas exchange in humans Flashcards iGCSE Biology

iGCSE Biology Flashcards – All Topics

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[h] Gas exchange in humans Flashcards iGCSE CIE Biology

[q] Label

 

[a]

  • Label:
    • A: Bronchus;
    • B: Trachea;
    • C: Diaphragm;
 

[q] Breathing

[a]

  • Breathing In
    • External Intercostal Muscles: Contract
    • Internal Intercostal Muscles: Relax
    • Rib Cage: Pulled upwards and outwards
    • Diaphragm: Contract, flattens
    • Lung Volume: Increase
    • Lung Pressure: Decrease
    • Movement of Air: Enters Lung
  • Breathing Out
    • External Intercostal Muscles: Relax
    • Internal Intercostal Muscles: Contract
    • Rib Cage: Pulled downwards and inwards
    • Diaphragm: Relax, becoming dome-shaped 
    • Lung Volume: Decrease
    • Lung Pressure: Increase
    • Movement of Air: Exits lung
 

[q] Carbon Dioxide Concentration & the Brain

[a]

  • Stimuli: Carbon dioxide concentration increased in the blood
  • Process:
    • The brain detects increases in carbon dioxide concentration in the blood by a receptor.
    • Brain sends impulses to intercostal muscles/diaphram.
    • Intercostal muscles/diaphragm contact more frequently.
    • Rate of expiration of the carbon dioxide increases.
      • Reason: Carbon Dioxide is acidic in solution and can denature enzymes
  • This process is known as homeostasis.
  • stimulus (is CO2) ; A acidic / pH, of blood decreases.
  • (CO2 / pH) detected by the brain;
  • by a receptor;
    ref to (named) neurone in context;
  • brain sends impulses to, (intercostal) muscles / diaphragm / effectors;
  • (intercostal) muscles / diaphragm / effectors, contract more (frequently);
  • negative feedback / homeostasis;
  • reflex / automatic / involuntary;
 

[q] Characteristics of respiratory surfaces (Alveoli)

[a]

  • Large surface area: to allow faster diffusion of gases across the surface
  • One cell thick: to ensure short diffusion distance
  • Good ventilation with air: to maintain a high concentration gradient
    • ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs
  • Good blood supply: to maintain a high concentration gradient
    • ensures that the oxygen concentration in the alveoli is higher than in the capillaries so oxygen moves from the alveoli to the blood.
  • Moist: Gases dissolve in the moisture before diffusing across the membrane, and cells die if not kept moist
  • Permeable

 

[q] EXHALATION

[a]

  1. The diaphragm muscles relax, allowing the diaphragm to rise.
  2. The external intercostal muscles relax, while the internal intercostal muscles contract, pulling the ribs downwards to bring about a forced expiration

 

[q] Inspired and Expired Air

[a]

  • Inspired Air:
    • Oxygen Content (%): 21
    • Carbon dioxide Content (%): 0.04
    • Nitrogen Content (%): 78
    • Water Vapor Content: Lower (Variable depending on humidity)
    •  
  • Expired Air:
    • Oxygen Content (%): 16
    • Carbon dioxide Content (%): 4
    • Nitrogen Content (%):  78
    • Water Vapor Content: Higher (Saturated)
 

[q] Name the Green Stars

[a]

 

[q] Name the Yellow Stars

[a]

 

[q] Structure of the Lungs

[a]

  • Cartilage:
    • Forms incomplete rings around trachea / bronchi;
    • Keeps airways open;
    • Reduces resistance to movement of air;
    • Protects airways;
    • Sound production in larynx;
  • Ribs:
    • Protects the lungs and heart.
  • Intercostal muscles:
    • Internal and external intercostal muscles work antagonistically in pairs to expand and contract the rib cage during breathing.
  • Diaphragm:
    • Creates a change in volume and pressure in the thorax, helping ventilate the lungs
  • Alveoli:
    • Where gas exchange occurs
    • Comprised of tiny air sacs with a capillary network.
    • Oxygen from the air diffuses into the capillaries, whilst waste carbon dioxide diffuses out. 
    • Waste gases are then breathed out.
 
  • Forms incomplete rings around, trachea / bronchi;
  • Keeps (named) airways open;
  • Reduces resistance to movement of air;
  • Protects (named) airways;
  • Sound production in larynx;
 

[q] The role of goblet cells, mucus and ciliated cells

[a]

  • Found in: Bronchus
  • Goblet cells produce mucus;
    • Mucus traps particles and pathogens;
    • Mucus protects lining;
  • Cilia beat / wafting
    • To move mucus up away from lungs.
      • Reduces risk of pathogens entering lungs.
 

[q] Cartilage

[a]

  • Forms incomplete rings around trachea / bronchi;
  • Keeps airways open;
  • Reduces resistance to movement of air;
  • Protects airways ;
  • Sound production in larynx;
 

[q] Ribs

[a] Protects the lungs and heart.

 

[q] Intercostal muscles

[a] Internal and external intercostal muscles work antagonistically in pairs to expand and contract the rib cage during breathing.

 

[q] Diaphragm

[a] Creates a change in volume and pressure in the thorax, helping ventilate the lungs

 

[q] Alveoli

[a]

  • Where gas exchange occurs
  • Comprised of tiny air sacs with a capillary network.
  • Oxygen from the air diffuses into the capillaries, whilst waste carbon dioxide diffuses out. 
  • Waste gases are then breathed out.
 

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