CHAPTER 22 Respiration: The Exchange of Gases Modules 22.1 – 22.4

Surviving in Thin Air The air at the height of the world’s highest peak, Mt. Everest, is very low in oxygen Even expert mountain climbers do not always survive the journey Thin air can weaken muscles, damage the digestive system, cloud the mind, and sometimes fill the lungs with blood

Geese have adaptations that allow them to fly over the Himalayas Their efficient lungs draw more oxygen from the atmosphere Their hemoglobin has a high affinity for oxygen They have a large number of capillaries to deliver this oxygen- rich blood to tissues and muscles

1 2 3 O2 Lung CO2 Breathing Circulatory system Transport of gases by the circulatory system Mitochondria 3 Servicing of cells within the body tissues O2 CO2 Capillary Cell Figure 22.1

Cut Cross section of respiratory surface (the skin covering the body) CO2 O2 Capillaries Figure 22.2A

Air sacs Tracheae Opening for air Body cell Tracheole Air sac Trachea Air Body wall Figure 22.5A, C

Body surface Respiratory surface (gill) CO2 Capillaries O2 Figure 22.2B

Lungs in land vertebrates Tracheae in insects Lungs in land vertebrates Body surface Body surface Respiratory surface (tracheae) Respiratory surface (within lung) O2 Body cells (no capillaries) CO2 O2 Capillary CO2 Figure 22.2C, D

Figure 22.5B

The human respiratory system Nasal cavity Pharynx (Esophagus) Left lung Larynx Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) Figure 22.6A

Figure 22.6C Oxygen-rich blood Oxygen-poor blood Bronchiole Alveoli Blood capillaries Figure 22.6B

Figure 22.10A

O2 O2 Heme group Iron atom O2 loaded in lungs O2 unloaded in tissues Polypeptide chain Figure 22.10B

TISSUE CELL CO2 produced INTERSTITIAL FLUID CO2 BLOOD PLASMA WITHIN CAPILLARY CO2 Capillary wall CO2 H2O RED BLOOD CELL Hemoglobin picks up CO2 and H+ H2CO3 Carbonic acid HCO3– + H+ Bicarbonate HCO3– Figure 22.11A

ALVEOLAR SPACE IN LUNG CO2 CO2 CO2 CO2 H2O Hemoglobin releases CO2 and H+ H2CO3 HCO3– + H+ HCO3– Figure 22.11B

22.8 Breathing ventilates the lungs Rib cage expands as rib muscles contract Rib cage gets smaller as rib muscles relax Air inhaled Air exhaled Lung Diaphragm INHALATION Diaphragm contracts (moves down) EXHALATION Diaphragm relaxes (moves up) Figure 22.8A

Brain Cerebrospinal fluid BREATHING CONTROL CENTERS—stimulated by: Pons Medulla CO2 increase / pH decrease in blood Nerve signal indicating low O2 level Nerve signals trigger contraction of muscles O2 sensor in artery Diaphragm Figure 22.9 Rib muscles

Figure 22.7A, B