Gaseous Exchange PDF

GASEOUS EXCHANG E  GASEOUS EXCHANGE Breathing / ventilation: mechanical process that moves air in and out of the respiratory organs. Gaseous exchange: exchange of gases; oxygen and carbon dioxide Cellular respiration: release of energy from glucose  WHY IS GASEOUS EXCHANG...

GASEOUS EXCHANG E  GASEOUS EXCHANGE Breathing / ventilation: mechanical process that moves air in and out of the respiratory organs. Gaseous exchange: exchange of gases; oxygen and carbon dioxide Cellular respiration: release of energy from glucose  WHY IS GASEOUS EXCHANGE NECESSARY? Supplies the body with oxygen Removal of CO2 Failure to remove causes carbonic acid to be formed Lowers pH REQUIREMENTS OF EFFICIENT GAS EXCHANGE ORGANS Large: maximise gas exchange Thin and permeable: easy and quick diffusion Moist: gases can dissolve Well-ventilated: brining fresh air to gas exchange surface Well-protected: prevent desiccation and injury Transport system: blood supply close to gas exchange surface GASEOUS EXCHANGE IN VARIOUS ORGANISMS INSECTS BONY FISH MAMMALS SURFACE AREA AND VOLUME OF ORGANISM As organism size increase; surface area to volume decreases Surface area – amount of oxygen can be absorbed Volume indicates amount of oxygen the organism requires. Unicellular organisms: large surface area compared to volume; rely on diffusion Large multicellular organism: small surface area compared to volume; lungs or gills COMPONENTS OF BREATHING SYSTEM Air passages Two lungs Respiratory muscles (intercostal and diaphragm) Respiratory centre in the brain  AIR PASSAGES: NASAL PASSAGES Function Anatomy Warms and moistens air Increase surface area Mucous membrane containing rich supply Cilia involved in movement and of blood vessels trapping of dust Turbinate bones: division by 3 bony plates Ciliated epithelium with goblet cells  PHARYNX (THROAT) Anatomy Connects nasal cavity with larynx Function Food and air passage  LARYNX (VOICE BOX) Anatomy Vocal cords Epiglottis Function Sound production Prevents food from entering larynx (closes glottis) TRACHEA (WINDPIPE) Anatomy C-shaped cartilaginous rings Lined with cilia Lined with goblet cells Function Takes air to and from lungs Keeps trachea open Movement of mucus Produces mucous for moisture and trapping foreign particles  BRONCHI Anatomy Two branches – left and right O-shaped cartilaginous rings Lined with cilia and goblet cells Function Movement of air to and from lungs  BRONCHIOLE (SMALL BRONCHI) Anatomy Narrow branches Lined with cilia and goblet cells Function Take air to and from alveoli  LUNGS Protection by rib cage Two membranes - Pleural membranes Contains pleural fluid Lungs are divided into lobes Right: three Left; two Consist of sac-like structures: infundibulum 🡪 smaller air sacs: alveoli  LUNGS ARE SUITED FOR THEIR FUNCTION Alveoli increase surface area Alveoli only 1 cell layer thick Moisture in alveoli Capillaries surround alveoli Surrounded by a double membrane Blood supply: Pulmonary artery 🡪 deoxygenated blood Pulmonary veins 🡪 oxygenated blood  VENTILATION – INHALATION / INSPIRATION Active process Diaphragm contracts Top to bottom increases External intercostal muscles contract Ribs move outwards Thoracic cavity enlarges Pressure in lungs decrease and become lower than atmospheric pressure Air flows into the lungs  EXHALATION / EXPIRATION Passive process Diaphragm relaxes and moves upwards External intercostal muscles relaxes and moves inward Pressure in lungs increase and become higher than atmospheric pressure Air flows out of the lungs EXTERNAL GASEOUS EXCHANGE ▪ Higher concentration of O2 in the alveolus than in the capillary ▪ O2 dissolves in the moisture and diffuses through alveolus wall and wall of capillary into the blood EXTERNAL GASEOUS EXCHANGE ▪ Higher concentration of CO2 in the capillary than in the alveolus ▪ CO2 diffuses through the wall of capillary and alveolus wall into the alveolus INTERNAL GASEOUS EXCHANGE In tissues ▪ Cellular respiration: needs O2 and produces CO2 ▪ Levels of O2 decreases and levels of CO2 increases ▪ O2: capillary → cell ▪ CO2: cell → capillary  TRANSPORT OF OXYGEN AROUND THE BODY 98% of oxygen binds to haemoglobin 2% dissolved in blood plasma  CARBON DIOXIDE TRANSPORT 7% dissolved in water and transported by blood plasma 23% combines with haemoglobin to form carbaminohaemoglobin Carbonic anhydrase splits CO2 at the lung surface 70% combines with water to form carbonic acid 🡪 transported as bicarbonate ions (HCO3) H atoms lower blood pH🡪 more O2 dissociate H ions attach to globin and acts as a buffer Carbonic anhydrase dissociates CO2 at lungs  Oxyhaemoglobin is split to release oxygen to cells Carbonic acid is present in blood and aids in dissociation of oxygen from haemoglobin. The amount of oxygen required at a site depends on the amount of carbonic acid present. Bӧhr effect  LUNG CAPACITY Amount of air that enters of leaves the lungs Spirometer Total volume = 5 L Tidal volume = 0.5 L normally inhaled/exhaled Vital capacity = exhaled with force; 3.5 L Residual volume = air remaining in lungs after forced exhalation; 1.5 L GASINHOUD/ GAS CONTENT  RESPIRATORY CENTRE Diagram page 2.39 Respiratory centre in Medulla oblongata of the brain Detects CO2 levels in blood and controls rate and depth of breathing. Nerve impulses is sent to breathing muscles to increase rate and depth. Coordination of all voluntary activity in body Autonomic Muscle tone, control; heart, balance respiratory, salivation, swallowing  EFFECTS OF ALTITUDE ON GASEOUS EXCHANGE Increase in altitude 🡪 less oxygen Hypoxia Nausea, headaches, dizzy Body needs to acclimatise Initial 🡪 🡪 Secondary: production of erythropoietin (hormone) 🡪 stiumulate red bone marrow to make more red blood cells EFFECTS OF SMOKING Cigarettes contains over 4000 harmful or poisonous substances. Nicotine Stimulates adrenalin Nicotine travels in blood Arteries narrow Increased heart rate and blood pressure; fatty acid addictive  Tar Carcinogenic Cancer – lung, mouth, trachea Damage to cilia Excess mucus production 🡪 infections Damage to alveoli Inflammation to air passages 🡪 chronic bronchitis  Carbon monoxide Colourless, poisonous Combines with haemoglobin Increased risk of heart attack Passive smoking SMOKING LEGISLATION IN SA RESPIRATORY DISEASES ▪Tuberculosis (TB) ▪Asthma ▪Hay fever ▪Bronchitis ▪Emphysema ▪Lung cancer  TUBERCULOSIS (TB) ▪ Mycobacterium tuberculosis (bacteria) – deadly ▪ Causes inflammation in the lungs ▪ infected person that coughs or sneeze can spread bacteria in droplets of saliva SYMPTOMS MANAGING Cough regularly ▪ Antibiotics for 6 months Coughing blood ▪ Side-effects – nausea and liver Chest pain damage Headache Fever Fatigue Weight loss ASTHMA ▪ Get asthma attacks and struggle to breathe ▪ Smooth muscles of the lining of bronchi or bronchioles contract ▪ Airways become narrow ▪ Caused by dust, pollen or polluted air ▪ Inhaler is required ▪ Relax smooth muscles – dilate airways  HAY FEVER ▪ Allergic reaction in the nasal passages ▪ Caused by dust or pollen ▪ Symptoms – watery eyes, runny nose and sneezing  BRONCHITIS ▪ Inflammation in the lining of bronchi ▪ Swelling of muscle and excessive release of mucus ▪ Caused by infection, polluted air or smoke ▪ Symptoms – cough regularly, shortness of breath and chest pains  EMPHYSEMA ▪ Alveoli walls are damaged ▪ Reduce gas exchange surface ▪ Caused by smoke ▪ Symptoms – coughing and shortness of breath ▪ Incurable LUNG CANCER ▪ Uncontrolled division of cancer cells (tumor) in the lung tissue ▪ Caused by smoke or other toxins in the air ▪ Symptoms – cough regularly, coughing up blood, shortness of breath and chest pains ▪ Treatment – physical removal, chemotherapy or radiotherapy