Circulation and Gas Exchange Chapter 42 Circulation and Gas Exchange

Chapter 42 Warm-Up How does the heart beat? What are the 3 types of blood cells and their function? What is the function of the lymphatic system? List the pathway of one molecule of O2 from the air into your pinky toe.

What you need to know: General characteristics of a respiratory surface How O2 and CO2 are transported in blood Pathway of O2 from airRBCtissues

Respiration Gas exchange supplies O2 for cellular respiration and disposes of CO2 Partial pressure = pressure exerted by a particular gas in a mixture of gases Gases always diffuse from higher partial pressure  lower partial pressure © 2011 Pearson Education, Inc.

Respiratory media: O2 in air or water Respiratory surface: body wall, skin, gills, tracheae, lungs Characteristics: Moist Large surface area-to-volume ratio Larger animals: associated with vascular system © 2011 Pearson Education, Inc.

Gills in aquatic animals Coelom Gills Gills Figure 42.22 Diversity in the structure of gills, external body surfaces that function in gas exchange. Tube foot Parapodium (functions as gill) (a) Marine worm (b) Crayfish (c) Sea star

Fish gills: absorb O2 through countercurrent exchange (blood flows opposite of water)

Tracheal systems in insects

Respiratory system in birds (lungs + air sacs)

Mammalian respiratory system

Pathway of O2 Nose/mouth: filtered, warmed, humidified Pharynx Larynx: contains vocal cords Trachea: windpipe; lined with cartilage Bronchi: branches to lungs Bronchioles Alveoli: air sacs for gas exchange Mucus: traps particles Cilia: sweeps particles up to pharynx

Alveoli

(a) The path of respiratory gases in the circulatory system Figure 42.30a 8 Exhaled air 1 Inhaled air 2 Alveolar spaces Alveolar epithelial cells CO2 O2 Alveolar capillaries 7 Pulmonary arteries 3 Pulmonary veins 6 Systemic veins 4 Systemic arteries Heart Figure 42.30 Loading and unloading of respiratory gases. Systemic capillaries CO2 O2 5 Body tissue (a) The path of respiratory gases in the circulatory system

Diaphragm: dome-shaped muscle separating thoracic/abdominal cavities

Control of Breathing in Humans Control center = medulla oblongata Responds to pH changes in blood High CO2  carbonic acid forms  lowers pH Sensors in the aorta and carotid arteries © 2011 Pearson Education, Inc.

Adaptations for gas exchange Hemoglobin: respiratory pigment in vertebrates 4 subunits, each with heme group with iron (Fe) Can carry 4 molecules of O2 Bohr shift: O2 dissociates from hemoglobin when blood pH is low Arthropods, mollusks: blue hemocyanin pigment contains copper (Cu) © 2011 Pearson Education, Inc.

How CO2 is transported Bicarbonate ions (70%) Hemoglobin (23%) Dissolved in plasma (7%) © 2011 Pearson Education, Inc.

Respiratory Adaptations of Diving Mammals Diving mammals have evolutionary adaptations that allow them to perform extraordinary feats For example, Weddell seals in Antarctica can remain underwater for 20 minutes to an hour For example, elephant seals can dive to 1,500 m and remain underwater for 2 hours High blood to body volume ratio Stockpile O2 and deplete it slowly Store oxygen in their muscles in myoglobin proteins © 2011 Pearson Education, Inc.

Respiratory Disorders Asthma: airways constricted Bronchitis: bronchi swollen and clogged Pneumonia: inflammation of lung caused by infection Tuberculosis (TB): infectious disease caused by M. tuberculosis Emphysema: lose elasticity of lung tissue Lung Cancer: abnormal cell growth in lungs