Respiration: Gas Exchange

1
Chapter 22

• Respiration Gas Exchange

2
Gas Exchange

• Includes breathing, transport of gases, and gas
  exchange at cellular level
• Take in oxygen from air, transport it to cells
  through blood, deliver to cells for cellular
  respiration (production of ATP)
• Cells release carbon dioxide, transported to
  lungs, release to air.

3
Respiratory Surfaces

• Gas exchange occurs at moist tissues
• Gasses are dissolved in water to pass through
  membranes
• Large amount of surface area is necessary
• Single layer of cells for exchange
• May be skin, gills, trachae, lungs

4
Human Respiratory System

• Air enters through the nostrils, flows through
  the nasal passages to be warmed and humidified
• The air passes through the pharynx to the larynx
  (voice box)
• Air passing the vocal cords produces sounds
• The air then passes through the trachea and into
  the bronchi, bronchioles and alveoli

5
Gas Exchange in Lungs

• The inner surface of the alveoli is the
  respiratory surface
• Oxygen passes through the single layer of cells
  into the capillaries around each alveolus
• Carbon dioxide diffuses in the reverse direction-
  from the blood through the respiratory surface to
  the air

6
Breathing

• Includes inhalation and exhalation
• Pull air in by expanding chest cavity
• Ribs move out diaphragm moves down
• Decreases pressure inside relative to outside
• Air moves in
• Reverse occurs in exhalation
• Maximum amount of air exchanged is vital capacity

7
Breathing Control

• Breathing control centers in brain regulate
  normal breathing and coordinates breathing and
  need for gas exchange
• Breathing is regulated by CO2 level in blood
• CO2 decreases pH of blood (acidic)
• Metabolism increase? increase in CO2
• Acidity leads medulla to increase breathing rate
• Hyperventilating decreases CO2
• Oxygen has less effect on breathing than CO2

8
Gas Transport

• Blood transport the respiratory gases (O2 and
  CO2)
• Oxygen enters blood from alveoli
• O2 attaches to hemoglobin of red blood cells
• O2 leaves blood and enters tissue cells
• Carbon dioxide leaves tissue cells and enters
  blood and is transported as carbonic acid
• CO2 leaves blood in alveoli

9
Fetal Gas Exchange

• Fetal gas exchange occurs across the placenta
• O2 from mothers blood diffuses across placenta
  into fetal circulation
• Lungs function after birth

10
Smoking

• Smoking damages lung tissue (alveoli)
• Respiratory system is protected by mucus,
  ciliated cells, and macrophages
• Remove pollutants and irritants
• Chemicals in tobacco smoke irritates cells lining
  trachea and bronchi
• Interferes with normal cleansing
• Leads to many diseases
• Quitting smoking can reverse damage

11

• Smoking causes lung cancer and contributes to
  heart disease

• Smoking also causes emphysema
• Cigarette smoke makes alveoli brittle, causing
  them to rupture
• This reduces thelungs capacity for gas exchange

Figure 22.7A, B