Respiration and Circulation Chapters 22 and 23

Copyright © 2009 Pearson Education, Inc. – The process of gas exchange is called respiration, the interchange of –O 2 and the waste product CO 2 –Between an organism and its environment Introduction: Surviving in Thin Air

Copyright © 2009 Pearson Education, Inc Gas Exchange Three phases 1. Breathing 2. Transport of oxygen and carbon dioxide in blood 3. Body tissues take up oxygen and release carbon dioxide Cellular respiration requires a continuous supply of oxygen and the disposal of carbon dioxide

Lung Exchange of gases with body cells Cell Capillary Mitochondria Breathing Circulatory system Transport of gases by the circulatory system CO 2 O2O2 O2O

Copyright © 2009 Pearson Education, Inc exchange across moist body surfaces Respiratory surfaces  Diffusion through skin – amphibians, worms  Lungs in birds, mammals, reptiles, amphibians  Book lungs in spider  Tracheal tubes in insects  Gills in fishes; amphibians

Cut CO 2 O2O2 Cross section of respiratory surface (the outer skin) Capillaries

Copyright © 2009 Pearson Education, Inc Cold water holds more oxygen than warm water Fresh water holds more oxygen than salt water Turbulent water holds more oxygen than still water

Copyright © 2009 Pearson Education, Inc Compared to water, using air to breathe has two big advantages –contains higher concentrations of O 2 –lighter and easier to move

Tracheae Air sacs Opening for air Body cell Tracheole Air sac Trachea Body wall CO 2 O2O2

Oxygen-rich blood Bronchiole Alveoli Oxygen-poor blood Blood capillaries Nasal cavity Left lung Pharynx Larynx Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) (Esophagus)

Lung Heart

Copyright © 2009 Pearson Education, Inc Pressure and Ventilation Breathing is the alternate inhalation and exhalation of air (ventilation) Inhalation occurs when 1. The rib cage expands 2. The diaphragm moves downward 3. The pressure around the lungs decreases 4. And air is drawn into the respiratory tract

Copyright © 2009 Pearson Education, Inc Exhalation occurs when 1. The rib cage contracts 2. The diaphragm moves upward 3. The pressure around the lungs increases 4. And air is forced out of the respiratory tract

Copyright © 2009 Pearson Education, Inc Breathing is usually under automatic control Breathing control centers in the brain sense and respond to CO 2 levels in the blood A drop in blood pH increases the rate and depth of breathing

Cerebrospinal fluid Pons Medulla Brain Nerve signals trigger contraction of muscles Diaphragm Rib muscles 1 Breathing control centers respond to pH of blood 2 Nerve signals indicating CO 2 and O 2 levels 3 CO 2 and O 2 sensors in aorta

Copyright © 2009 Pearson Education, Inc Most animals transport O 2 bound to proteins called respiratory pigments –Copper-containing pigment is used by –Molluscs –Arthropods –Iron-containing hemoglobin –Is used by almost all vertebrates and many invertebrates –Transports oxygen, buffers blood, and transports CO 2

O 2 loaded in lungs O 2 unloaded in tissues Iron atom Polypeptide chain Heme group O2O2 O2O2

Copyright © 2009 Pearson Education, Inc – A human fetus –exchanges gases with maternal blood in the placenta – In the placenta, capillaries of maternal blood and fetal blood run next to each other –The fetus and mother do not share the same blood

The Path 1. Oxygen in lungs (alveoli) move into capillaries 2. CO 2 moves from capillaries into lungs 3. O 2 is bound to hemoglobin (red blood cells) and is transported throughout the body 4. O 2 moves out of capillaries into fluid around cells and into cells 5. CO 2 moves out of cells into fluid and into capillaries 6. CO 2 is coverted to bicarbonate and carried to lungs  converted back to CO 2

Right atrium To lung From lung Semilunar valve Atrioventricular (AV) valve Left atrium To lung From lung Semilunar valve Atrioventricular (AV) valve Right ventricle Left ventricle

The Path 1.Leaves left ventricle to aorta 2.Moves from aorta to arteries to arterioles to capillaries 3.Exchanges gases and nutrients with cells 4.Moves from capillaries to venules to veins 5.Moves to right atrium  to right ventricle 6.Moves to lungs for gas exchange 7.Moves to left atrium  to left ventricle

Connective tissue Capillary Venule Smooth muscle Arteriole ArteryVein Valve Epithelium Basal lamina Epithelium Smooth muscle Epithelium Connective tissue

Nuclei of smooth muscle cells Red blood cell Capillary

Copyright © 2009 Pearson Education, Inc Blood pressure –Highest in arteries –Lowest in veins measured as –Systolic pressure—caused by ventricular contraction –Diastolic pressure—low pressure between contractions