1.UNIT 9:RESPIRATORY SYSTEM ANDGASEOUS EXCHANGE

2. BREATHING Sequence of events that results in gas exchange. In terrestrial vertebrates it includes 3 steps:1. Ventilation: Inspiration and expiration.2. External respiration: Gas exchange between air (in lungs) and blood. Blood then transport Oxygen to the body tissue cells.3. Internal respiration: Gas exchange between blood and tissue fluid. Blood then transports carbon dioxide to the lungs. 3. Gas exhange surfacemust be:Alveoli filled with air (gas) ExternalMoistrespiration Carbon dioxide oxygenThinLarge in relation of sizeof body Blood part of circulatory system contain red pigment Process: Diffusion ofhemoglobin, togasses (oxygen and transport gassescarbon dioxide Internal respination oxygen Carbon dioxide Body cells surrounded by tissue fluid 4. Cellular respiration Is the process whereby an organism usesoxygen and food to produce energy (ATP) and2 by products e.g. water and carbon dioxide Glucose + O2ATP + H2O + CO2Therefore gaseous exchange is necessary to getoxygen for cellular respiration. 5. HUMAN RESPIRATORY SYSTEM Consists of: 1. Nose 2. Air passages: Pharynx Trachea Bronchus Bronchioles3. Lungs Alveoli 6. Nose has a nasal cavity thatleads to the pharynx. Nasal cavity is lined with cilia NOSEand hairs and goblet cells thatmake mucus (anti-septic andmoisten air) filter the air dust, pollen and other foreignmaterial sticks to it. 3 x turbinate bones divide thenasal cavity into 4 passages This enlarges the surface of thenasal cavity For warming,cleaning and moisten of air. Several surface blood vesselshelp to warm air. 7. AIRPASSAGES Pharynx pass air formnose to trachea via larynx. Trachea: long, straighttube kept open by C-shaped cartilage rings. Trachea lined with ciliaand goblet cells (mucusproduction) trapsforeign particles 8. Lining of airpassagesCILIA (SEM) TRACHEAL LINING 9. AIRPASSAGES: BRONCHI AND BRONCHIOLES Trachea divides in a rightand left bronchus consist of C-shapedcartilage rings and linedRight bronchus-shortwith goblet cells (mucus)Branch in 3 Left bronchus long, Bronchi branch in lung tobranch in 2form bronchioles branch further andcartilage rings disappears lead air to air sacs oflung.Bronchiole 10. LUNGS Right lung (3 lobes - shorter)and left lung (2 lobes longer,narrow) Spongy, elastic pink organ. Consists of several air sacscalled alveoli. Alveoli are grouped togetherand form the endings of thebronchioles. 11. ALVEOLI Lined with single layersquamous epithelial cells Thin easy diffusion of gas. Alveoli is surrounded by anetwork of blood capillaries gasses diffuse into and out ofblood. Alveoli is lined with moistlayer oxygen dissolves inmoisture and diffuses throughalveoli wall into bloodcapillary. 12. Pulmonary vein Pulmonary artery(Oxygenated (Deoxygenatedblood) blood)Turbinate bonesPharynxAlveoliTracheaBronchusBronchioleDiaphragm SEMTEM 13. BREATHING - The process whereby air (gasses) move in and out of the body.EXPIRATIONINSPIRATION INSPIRATION Air inhaledEXPIRATION Air exhaledRib cageexpands asRib cage getsrib muscles smaller as ribcontractmuscles relaxWhen pressure inlungs increase air isWhen pressure inpushed out DiaphragmDiaphragmlungs decrease air contracts (moves relaxes (movesrush in down)up) 14. TIDAL VENTILATION MECHANISM Air moves in and out of the body via the sameroute. All terrestrial vertebrates do this except for birds. The lungs are not completely emptied duringeach breathing cycle. The air entering mixes with used air remaining inthe lungs. This help to conserve water, but decreases gas-exchange efficiency 15. Determining lung capacity A spyrometer can be used to determine how much airenters the lungs. Your lungs has a volume of +/- 5 liters. During a normal breath, only 0.5 liters of air isexchanged This air is known as tidal volume. During forced breathing, as much as 3.5 liters of air canbe exchanged, this is known as vital capacity. (The fitteryou are, the higher your vital capacity.) +/- 1.5 liters of air always remains in the lungs this airis known as residual air/volume. 16. RESPIRATORY CENTER Normal breathing rate for adults: 12 20ventilations per minute. Respiratory Center in the Medulla Oblongataof the brain controls breathing. The respiratory center send impulses throughthe phrenic nerve to the diaphragm andthrough the intercostal nerve to theintercostal muscles to either contract or relax.(Contract during inspiration and relax duringexpiration) 17. Nervous control of breathing BrainRespiratory center automaticallyregulates breathingIntercostal nervesstimulate theintercostal musclesIntercostal musclesPheric nerve stimulates thediaphragmDiaphragm 18. GAS EXCHANGE Gas exchange between air inlungs and blood EXTERNAL RESPIRATIONINTERNAL RESPIRATION Movement driven by diffusion Gas exchange betweengradient. ( [] to [])blood and tissue fluid Gasses exerts pressure, the Movement driven byamount of pressure each gasdiffusion gradient. ( [] toexerts is called partial [])pressure (PO2 and PCO2) Gasses exerts pressure, the amount of pressure each gas exerts is called partial pressure (PO2 and PCO2) 19. EXTERNAL RESPIRATSION If PO2 differs across a membrane oxygen willdiffuse from a high to a low pressure. If PCO2 differs across a membrane carbondioxide will diffuse from a high to a lowpressure. During inspiration the alveoli fills with air higher PO2 and lower PCO2 than blood. Oxygen diffuse from alveoli into blood andcarbon dioxide diffuse from blood into alveoli. 20. INTERNAL RESPIRATION When blood reaches the tissue, cellularrespiration in cells causes the tissue fluid tohave a lower PO2 and a higher PCO2 than theblood. Thus oxygen diffuse from a high pressure inthe blood to a low pressure in the tissue fluidand eventually in the tissue cells. Carbon dioxide diffuse from a high pressure inthe tissue fluid to a low pressure in the blood. 21. TRANSPORT OF OXYGEN Most oxygen is transported by hemoglobin(red pigment protein in erythrocytes). Oxygen combines with hemoglobin to formoxyhemoglobin.Hb +O2 = HbO2HemoglobinOxygenOxyhemoglobin A small amount of oxygen is transported insolution in the blood plasma.