Cross section of the respiratory surface (the outer skin) Capillaries CO 2 O2O2 Body surface Respiratory surface (gills) Capillary CO 2 O2O2
Figure 22.3 Oxygen-poor blood Water flow between lamellae Lamella Blood flow through capillaries in a lamella Oxygen-rich blood Blood vessels Gill arch Operculum (gill cover) Gill filaments Diffusion of O 2 from water to blood Countercurrent exchange Water flow, showing % O 2 Blood flow in simplified capillary, showing % O Water flow
Air sacs Tracheoles Tracheae Opening for air Air sac Body cell Tracheole Trachea Body wall CO 2 O2O2 Body surface Respiratory surface (tips of tracheae) CO 2 O2O2 Body cells (no capillaries)
Figure 22.2D CO 2 O2O2 Body surface Capillary Respiratory surface (within lung) O2O2 CO 2
O2O2 H2OH2O Light Sugar O2O2 CO 2 H2OH2O and minerals Plants - Gas exchange thru leaves
Dermal tissue system Ground tissue system Vascular tissue system Key Sheath Stoma Guard cells Vein Phloem Xylem Eudicot leaf Cuticle Upper epidermis Lower epidermis Mesophyll Stoma = site of CO 2 / O 2 exchange
Guard cells Stoma closing Vacuole Stoma H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O K Stoma opening H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O Guard cells of stomates CLOSE when too much water is lost. When water is plentiful, guard cells actively transport K+ INTO cell, water follows, and stoma open.
Nasal cavity Pharynx Larynx (Esophagus) Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) Blood capillaries Bronchiole Alveoli CO 2 O2O2 Oxygen-poor blood From the heart To the heart Oxygen-rich blood Left lung Alveoli are well adapted for gas exchange with high surface areas of capillaries. – O 2 diffuses into the blood and – CO 2 diffuses out of the blood. Alveoli are site of gas exchange in lungs!
CO 2 in exhaled air Alveolar epithelial cells O 2 in inhaled air Air spaces Alveolar capillaries of lung CO 2 O2O2 O2O2 CO 2 -rich, O 2 -poor blood O 2 -rich, CO 2 -poor blood Heart Tissue capillaries O2O2 CO 2 Interstitial fluid Tissue cells throughout the body CO 2 O2O2 Gas Exchange occurs by passive diffusion!!! Gasses diffuse towards regions of lowest partial pressure. (Partial pressure = measure of concentration of gas dissolved in liquid)
Figure 22.10_1 Alveolar capillaries of lung O2O2 CO 2 CO 2 -rich, O 2 -poor blood O 2 -rich, CO 2 -poor blood Heart Tissue capillaries O2O2 CO 2 [CO 2 ] LOWEST in alveoli and tissue capillaries [CO 2 ] HIGHEST in tissues and blood arriving to lung from tissues [O 2 ] LOWEST in blood at tissues and in blood arriving at lung [O 2 ] HIGHEST in alveoli and blood arriving TO tissues
1 2 Cerebrospinal fluid Brain Nerve signals trigger contraction of the rib muscles and diaphragm. Diaphragm Rib muscles Breathing control center responds to the pH of blood and cerebrospinal fluid. 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. Medulla Breathing is automatically controlled
Cerebrospinal fluid Medulla Brain Nerve signals trigger contraction of the rib muscles and diaphragm. 1 Diaphragm Rib muscles Breathing control center responds to the pH of blood and cerebrospinal fluid. 2 Heart CO 2 and O 2 sensors in the aorta Nerve signals indicate CO 2 and O 2 levels. 3 Additional sensors in aorta may monitor O2 levels