CHP 10 Gaseous Exchange PDF

CHP 10: Gaseous Exchange & Its Control FSPB 0034 BIOLOGY DR NOORHASYIMAH ISMAIL Content 10.1 Introduction 10.2 Respiratory Pigment 10.3 Regulation of Gas Exchange in Human 10.4 Mechanism of Gas Exchange in Animals  Gaseous Exchange & Its Control LEARNING OBJECTIVES By the end of...

CHP 10: Gaseous Exchange & Its Control FSPB 0034 BIOLOGY DR NOORHASYIMAH ISMAIL Content 10.1 Introduction 10.2 Respiratory Pigment 10.3 Regulation of Gas Exchange in Human 10.4 Mechanism of Gas Exchange in Animals  Gaseous Exchange & Its Control LEARNING OBJECTIVES By the end of this topic, students should be able to: 1. Describe the structure of hemoglobin and its characteristics as a respiratory pigment. 2. Explain mechanism of gas exchange in human and animals. 3. Explain the regulation and control of gas exchanges in human.  10.1 Introduction 10.1.1 Overview The Human Transport of Gases Mechanisms of Gas Respiratory Exchange in Animals System in the Human Body  10.1 Introduction 10.1.1 Overview ★ Lungs are large, paired, spongy organs. ★ Located in the thoracic cavity (chest). ★ Each lung is covered by pleural membrane. ★ Right lung consists of three lobes. ★ Left lung consists of two lobes. ★ Air passage: nostrils → nasal cavities → pharynx → larynx → trachea → bronchi → bronchioles → alveoli  10.1 Introduction 10.1.1 Overview Overview of Cellular Respiration Checkpoint question Humans cannot survive for more than a few minutes without O2. Why?  10.2 Respiratory Pigment 10.2.1 Erythrocyte & Hemoglobin ★ Most organism needs respiratory pigments to transport O2 & CO2 ★ Respiratory pigment is a molecule that increases the ability to transport respiratory gases. ★ In most vertebrates, 2 types of pigment are: ★ An erythrocyte or red blood cell (RBC) has no Hemoglobin (pigment in nucleus & lacks organelles ⇒ maximizes space for hemoglobin in RBC erythrocytes) ★ RBC also has no mitochondria ⇒ WHY? Myoglobin (pigment in muscles)  10.2 Respiratory Pigment 10.2.2 Hemoglobin Hemoglobin carries O2, helps transport CO2, and buffers the blood Most animals transport O2 bound to proteins called respiratory pigments. O2 does not readily dissolve in blood, so O2 does not tend to move from the air into the blood on its own. The O2 binds to respiratory pigment to be transported throughout the body. A blue, copper-containing pigment is used by many mollusks and arthropods. Red, iron-containing hemoglobin is used by almost all vertebrates and many invertebrates, transports oxygen and CO2, and buffers blood.  10.2 Respiratory Pigment 10.2.2 Hemoglobin ★ Consists of 4 polypeptide chains or Structure of Hemoglobin (Hb) subunits ★ 2 α-chains and 2 β-chains ★ Each chain is attached to one heme (iron- porphyrin) ring ★ An iron atom is located in the center of heme ring ★ Each iron atom can bind with one molecule of O2 ★ One Hb molecule can bind with four O2 molecules ★ Made up of a protein known as globin in red blood cells ★ Conjugated protein with a quaternary structure  10.3 Regulation of Gas Exchange in Human 10.3.1 Gas Exchange in Human Gas exchange, the interchange of O2 and CO2 between an organism and its environment, provides O2 for cellular respiration and removes its waste product, CO2. Three phases of gas exchange occur in humans and other animals with lungs: 1. breathing, 2. transport of gases by the circulatory system, and 3. exchange of gases with body cells: Body tissues take up O2 from the blood and release CO2 to the blood.  10.3 Regulation of Gas Exchange in Human 10.3.1 Gas Exchange in Human In mammals, branching tubes convey air to lungs located in the chest cavity Inhaled air then passes through the pharynx The diaphragm and larynx into the trachea, bronchi, and separates the abdominal cavity from bronchioles to the alveoli. the thoracic cavity and Specialized secretions called surfactants helps ventilate the lungs. prevent the moist surfaces of alveoli from sticking shut. In mammals, air is inhaled through the nostrils into the Mucus and cilia in the respiratory passages nasal cavity, protect the lungs. filtered by hairs and mucous surfaces, warmed and humidified, and sampled for odors.  10.3 Regulation of Gas Exchange in Human 10.3.1 Gas Exchange in Human Checkpoint question What keeps the bronchi free of any dust or pollen breathed in?  10.3 Regulation of Gas Exchange in Human 10.3.2 Negative Pressure Breathing Negative pressure breathing ventilates your lungs Breathing is ventilation of the lungs through alternating inhalation and exhalation. In humans and other mammals, ventilation occurs by negative pressure breathing, a system in which air is pulled into the lungs. The contraction of rib muscles and the diaphragm expands the thoracic cavity, reducing air pressure in the alveoli and drawing air into the lungs.  10.3 Regulation of Gas Exchange in Human 10.3.3 Breathing Control Center Breathing control centers in the brain coordinate breathing with body needs by sensing and responding to the pH of the cerebrospinal fluid, which indicates CO2 level in the blood. A drop in blood pH triggers an increase in the rate and depth of breathing. Checkpoint question How is the increased need for O2 during exercise accommodated by the breathing control centers?  10.3 Regulation of Gas Exchange in Human 10.3.4 Transport of Gases Blood transports respiratory gases The heart pumps oxygen-poor blood to the lungs, where it picks up O2 and drops off CO2. Oxygen-rich blood returns to the heart and is pumped to body cells, where it drops off O2 and picks up CO2. A mixture of gases, such as air, exerts pressure. Each kind of gas in a mixture accounts for a portion of the total pressure of the mixture. Thus, each gas has a partial pressure. Molecules of each kind of gas diffuse down a gradient of their own partial pressure, moving from regions of higher partial pressure to those of lower partial pressure.  10.3 Regulation of Gas Exchange in Human 10.3.5 Human Fetus & Mother’s Blood CONNECTION: The human fetus exchanges gases with the mother’s blood Fetal hemoglobin attracts O2 more strongly than does adult hemoglobin. This enhances oxygen transfer from maternal blood in the placenta. At birth, rising CO2 in fetal blood stimulates the breathing control center to initiate breathing.  10.4 Mechanism of Gas Exchange in Animals 10.4.1 Respiratory Surfaces & Organs Respiratory surfaces must be thin and moist for diffusion of O2 and CO2 to occur. Some animals use their entire skin as a gas exchange organ. In most animals, gills, a tracheal system, or lungs provide large respiratory surfaces for gas exchange. © 2018 Pearson Education Ltd. Skin as respiratory organ  10.4 Mechanism of Gas Exchange in Animals 10.4.1 Respiratory Surfaces & Organs © 2018 Pearson Education Ltd. Gills Trachea Lung Checkpoint question How does the structure of the respiratory surface of a gill or lung fit its function? 22.2 Animals exchange O2 and CO2 across moist body surfaces Respiratory surfaces must be thin and moist for diffusion of O2 and CO2 to occur. Some animals use their entire skin as a gas exchange organ. In most animals, gills, a tracheal system, or lungs provide large respiratory surfaces for gas exchange. Checkpoint question How does the structure of the respiratory surface of a gill or lung fit its function? © 2018 Pearson Education Ltd.  10.4 Mechanism of Gas Exchange in Animals 10.4.2 Respiratory Surfaces & Organs: Gills VISUALIZING THE CONCEPT: Gills are adapted for gas exchange in aquatic environments Gills absorb O2 dissolved in water. In a fish, gas exchange is enhanced by ventilation, the flow of water (or air) over the respiratory surface, and countercurrent exchange, the transfer of a substance such as oxygen between two fluids flowing in opposite directions.  10.4 Mechanism of Gas Exchange in Animals 10.4.3 Respiratory Surfaces & Organs: Trachea The tracheal system of insects provides direct exchange between the air and body cells There are two big advantages to breathing air: 1. Air contains a much higher concentration of O2 than does water. 2. Air is much lighter and easier to move than water. The tracheal system of insects, with respiratory surfaces at the tips of tiny branching tubes inside the body, transports O2 directly to body cells and moves CO2 away from them and greatly reduces evaporative water loss. The largest tubes, called tracheae, connect to external openings spaced along the body. End of CHP 10 Any questions?