Respiration Chapter 34

Atmospheric Pressure Pressure exerted by the weight of the air on objects on Earth’s surface At sea level = 760 mm Hg Oxygen is 21% of air

Fick’s Law Describes the rate at which a substance (such as oxygen) will diffuse across a membrane (such as a respiratory surface) Rate is proportional to the pressure gradient across the membrane and to the surface area of the membrane

Surface-to-Volume Ratio As animal size increases, surface-to-volume ratio decreases Respiratory surfaces tend to be large and thin moist Small, flattened animals can use the body surface as their respiratory surface Larger animals have special structures to increase respiratory surface gills or lungs tracheal tubes

Invertebrate Respiration Examples of respiratory surfaces

Fish Gills Bony fish respiration

Countercurrent Flow Blood flow runs in the opposite direction of water flow over the filaments This enhances movement of oxygen from water to blood respiratory surface direction of water flow direction of blood flow oxygenated blood back toward body oxygen-poor blood from deep in body

Vertebrate Lungs Originated in some fishes as outpouching from gut wall Allow gas exchange in oxygen-poor aquatic habitats and on land salamander reptile

Avian Respiration Lungs are inelastic and connect to a series of air sacs Air is drawn continually though each lung air sacs air sacs lung air sacs

Avian Respiration Bird respiration

Human Respiratory System

Respiration The two systems that supply oxygen and eliminate carbon dioxide are the Cardiovascular System Respiratory System Failure of either of the two systems: disrupts homeostasis promotes cell death from oxygen starvation and waste product overflow

Respiration 5 activities of the respiratory process: Ventilation air moving from atmosphere into our lungs External respiration moving O2 and CO2 to and from our alveoli and pulmonary vessels Transport of gases how O2 and CO2 are carried in the blood Internal respiration moving of O2 and CO2 in and out of the tissues of the body Cellular respiration how tissues use O2 to produce ATP

Organs Nose – Openings – internal nares Nasal cavity divided by the nasal septum Functions of the Nose Interior structures warm, moisten and filters air Receives olfactory stimuli Provides a resonating chamber for speech sounds

Air Passage Air passes through nasal convolutions Mucous membrane lines the cavity and shelves traps particles More surface area for warming (from capillary beds) filtering moistening air

Pharynx Composed of skeletal muscle lined with mucous membrane Passageway for air and food Resonating chamber for speech sounds

Larynx Voice Box connects pharynx with trachea Thyroid forms front wall (triangular) Adam’s apple Epiglottis – (epi-above; glottis-tongue) leaf shaped covered by epithelium on top of larynx “leaf” free – trap door

Trachea Wall is lined with mucous membrane and supported by cartilage Pseudo stratified ciliated columnar epithelium makes up the inside of the trachea Ciliated columnar cells cilia Goblet cells mucous

Lungs Pleural membrane double layer that encloses and protects each lung Parietal pleura membrane outer layer is attached to the wall of the thoracic cavity and diaphragm Visceral pleura covers the lungs themselves Pleural cavity space between the two membranes contains fluid to reduce friction 19

Bronchi The trachea divides into a right and left primary bronchus The right is more vertical, shorter and wider than left more objects lodge here Structured like the trachea Incomplete rings of cartilage Lined with pseudo stratified ciliated epithelium

Secondary Bronchi One leads to each lobe of the lungs Right lung=3 lobes Left lung= 2 lobes Secondary bronchi break down to tertiary bronchi bronchioles terminal bronchioles

Alveolus Alveolus cup-shaped projection lined with epithelium Alveolar sacs two or more alveoli that share a common opening Gas exchange takes place here at the alveoli Arteriole and venule surround alveolus to form a capillary network Lungs contain 300 million alveoli large surface area

Oxygen Transport Most oxygen is carried bound to hemoglobin in red blood cells Hemoglobin has a great affinity for oxygen when it is at high partial pressure in pulmonary capillaries Lower affinity for oxygen in tissues, where partial pressure is low

alpha globin alpha globin heme beta globin beta globin a) Hemoglobin b) Myoglobin

Globin and hemoglobin structure Oxygen Transport Globin and hemoglobin structure

Bicarbonate Formation H2CO3 carbonic acid CO2 + H2O HCO3– bicarbonate + H+ 3 ways CO2 transported: some is dissolved in the plasma 7% some binds to hemoglobin 23% most carbon dioxide is transported as bicarbonate 70%

Animation: CO2 Tissues to Blood Right click slide / Select play

CO2 produced during cellular respiration lowers blood pH and decreases the affinity of hemoglobin for O2 Bohr shift Hemoglobin also assists in preventing harmful changes in blood pH and plays a minor role in CO2 transport 30

O2 saturation of hemoglobin (%) 100 pH 7.4 80 pH 7.2 Hemoglobin retains less O2 at lower pH (higher CO2 concentration 60 O2 saturation of hemoglobin (%) 40 20 Figure 34.25b Dissociation curves for hemoglobin at 37°C (part 2: variable pH) 20 40 60 80 100 PO2 (mm Hg) (b) pH and hemoglobin dissociation 31

Partial Pressure Gradients

Partial Pressure Gradients 3 pressures involved in pulmonary ventilation Atmospheric pressure air outside the body Intrapulmonary pressure pressure within alveoli of the lungs Intraplueral pressure pressure within the pleural cavity space between visceral and parietal pleural membrane

Breathing Moves air into and out of lungs Occurs in a cyclic pattern called the respiratory cycle One respiratory cycle consists of inhalation and exhalation 12 – 20 adults 15 – 30 children 25 – 50 infants

Inhalation Diaphragm flattens External intercostal muscles contract Volume of thoracic cavity increases Lungs expand Air flows down pressure gradient into lungs

Normal Passive Exhalation Muscles of inhalation relax Thoracic cavity recoils Lung volume decreases Air flows down pressure gradient and out of lungs

Rib cage expands as rib muscles contract. Rib cage gets smaller as relax. Air inhaled. Air exhaled. Lung Diaphragm Figure 34.22 Negative pressure breathing Inhalation: Diaphragm contracts (moves down). 1 Exhalation: Diaphragm relaxes (moves up). 2 37

Active Exhalation Muscles in the abdomen and the internal intercostal muscles contract This decreases thoracic cavity volume more than passive exhalation A greater volume of air must flow out to equalize intrapulmonary pressure with atmospheric pressure

4 Respiratory Volumes Tidal volume (500 mL) normal quiet breathing Inspiratory reserve volume (3100 mL) forced inhalation Expiratory reserve volume (1200 mL) forced exhalation Residual volume (1200 mL) air left in lungs after expiratory volume

Control of Breathing Medulla oblongata sets main rhythm Magnitude (depth) of breathing depends on concentration of oxygen and H+ Brain detects H+ increases breathing Carotid bodies and aortic bodies detect drop in oxygen, increase breathing

Homeostasis: Blood pH of about 7.4 Stimulus: Rising level of CO2 in tissues lowers blood pH. Figure 34.23-1 Homeostatic control of breathing (step 1) 41

Homeostasis: Blood pH of about 7.4 Stimulus: Rising level of CO2 in tissues lowers blood pH. Carotid arteries Figure 34.23-2 Homeostatic control of breathing (step 2) Sensor/control center: Aorta Cerebro- spinal fluid Medulla oblongata 42

Homeostasis: Blood pH of about 7.4 Stimulus: Rising level of CO2 in tissues lowers blood pH. Response: Signals from medulla to rib muscles and diaphragm increase rate and depth of ventilation. Carotid arteries Figure 34.23-3 Homeostatic control of breathing (step 3) Sensor/control center: Aorta Cerebro- spinal fluid Medulla oblongata 43

Homeostasis: Blood pH of about 7.4 CO2 level decreases. Stimulus: Rising level of CO2 in tissues lowers blood pH. Response: Signals from medulla to rib muscles and diaphragm increase rate and depth of ventilation. Carotid arteries Figure 34.23-4 Homeostatic control of breathing (step 4) Sensor/control center: Aorta Cerebro- spinal fluid Medulla oblongata 44

Humans at High Altitude Permanent residents of high areas have More vascularized lungs Larger ventricles in heart More mitochondria in muscle Acclimatization Changes in rate of breathing, heart output Kidney secretes erythropoitein; red cell production increases

hemoglobin of llamas hemoglobin of humans hemoglobin of other mammals (combined range)

Carbon Monoxide (CO) Colorless, odorless gas Competes with oxygen for binding sites in hemoglobin Binding capacity is at least 200 times greater than oxygen’s Exposure impairs oxygen delivery

The Bends Pressure increases with depth Increases N2 dissolved in blood Can bubble out if diver ascends too fast Pain in joints, impaired vision, paralysis

Heimlich Maneuver Heimlich maneuver

Emphysema An irreversible breakdown in alveolar walls Lungs become inelastic May be caused by a genetic defect Most often caused by smoking

Bronchitis Irritation of the ciliated epithelium that lines the bronchiole walls Air pollutants, smoking, or allergies can be the cause Excess mucus causes coughing, can harbor bacteria Chronic bronchitis scars and constricts airways

Impacts, Issues Video Up In Smoke

Impacts, Issues-Up In Smoke Filmy gunk from pathogens promotes: asthma attacks bronchitis colds Nicotine: constricts blood vessels raises blood pressure makes blood stickier and clots more likely Costs of smoking: clogged arteries heart attacks strokes lung cancer