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Unit 3 respiratory system and gas exchange
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Unit 3 respiratory system and gas exchange



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  • 1.  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.
  • 2. Gas exhange surfacemust be: Alveoli filled with air (gas) External•Moist respiration Carbon dioxide oxygen•Thin•Large in relation ofsize of body Blood – part of circulatory system contain red pigment Process: Diffusion of – hemoglobin, to gasses (oxygen and transport gasses carbon dioxide Internal respination oxygen Carbon dioxide Body cells surrounded by tissue fluid
  • 3.  Is the process whereby an organism uses oxygen and food to produce energy (ATP) and 2 by products e.g. water and carbon dioxide Glucose + O2 ATP + H2O + CO2Therefore gaseous exchange is necessary for to get oxygen for cellular respiration.
  • 4.  Consists of:1. Nose2. Air passages:  Pharynx  Trachea  Bronchus  Bronchioles3. Lungs – Alveoli
  • 5.  Nose has a nasal cavity that leads to the pharynx. Nasal cavity is lined with cilia and hairs and goblet cells that make mucus (anti- septic and moisten air)– filter the air – dust, pollen and other foreign material sticks to it. 3 x turbinate bones divide the nasal cavity into 4 passages – This enlarges the surface of the nasal cavity – For warming, cleaning and moisten of air. Several surface blood vessels help to warm air.
  • 6.  Pharynx – pass air form nose to trachea via larynx. Trachea: long, straight tube kept open by C- shaped cartilage rings. Trachea – lined with cilia and goblet cells (mucus production) – traps foreign particles
  • 8.  Trachea divides in a right and left bronchus – consist of C-shaped cartilage rings and lined with Right bronchus-short goblet cells (mucus) Branch in 3 Left bronchus – Bronchi branch in long, branch in 2 lung to form bronchioles – branch further and cartilage rings disappears – lead air to air sacs of lung. Bronchiole
  • 9.  Right lung (3 lobes - shorter) and left lung (2 lobes – longer, narrow) Spongy, elastic pink organ. Consists of several air sacs called alveoli. Alveoli are grouped together and form the endings of the bronchioles.
  • 10.  Lined with single layer squamous epithelial cells – Thin easy diffusion of gas. Alveoli is surrounded by a network of blood capillaries – gasses diffuse into and out of blood. Alveoli is lined with moist layer – oxygen dissolves in moisture and diffuses through alveoli wall into blood capillary.
  • 11. Pulmonary vein Pulmonary (Oxygenated artery blood) (Deoxygenated blood)Turbinate bones Pharynx Alveoli Trachea BronchusBronchioleDiaphragm SEM TEM
  • 12.  INSPIRATION  EXPIRATION Air inhaled Air exhaledRib cageexpands Rib cageas rib getsmuscles smaller ascontract rib muscles relax When pressure in lungs increase –When pressure in air is pushed out INSPIRATIONlungs decrease – Diaphragm EXPIRATION Diaphragm contracts relaxesair rush in (moves down) (moves up)
  • 13.  Air moves in and out of the body via the same route. All terrestrial vertebrates do this except for birds. The lungs are not completely emptied during each breathing cycle. The air entering mixes with used air remaining in the lungs. This help to conserve water, but decreases gas-exchange efficiency
  • 14.  A spyrometer can be used to determine how much air enters the lungs. Your lungs has a volume of +/- 5 liters. During a normal breath, only 0.5 liters of air is exchanged – This air is known as tidal volume. During forced breathing, as much as 3.5 liters of air can be exchanged, this is known as vital capacity. (The fitter you are, the higher your vital capacity.) +/- 1.5 liters of air always remains in the lungs – this air is known as residual air/volume.
  • 15.  Normal breathing rate for adults: 12 – 20 ventilations per minute. Respiratory Center in the Medulla Oblongata of the brain controls breathing. The respiratory center send impulses through the phrenic nerve to the diaphragm and through the intercostal nerve to the intercostal muscles to either contract or relax. (Contract during inspiration and relax during expiration)
  • 16. Brain Respiratory center automatically regulates breathing Intercostal nerves stimulate the intercostal muscles Intercostal musclesPheric nerve stimulatesthe diaphragm Diaphragm
  • 17.  Gas exchange between  Gas exchange between air in lungs and blood blood and tissue fluid Movement driven by  Movement driven by diffusion gradient. ( [] to diffusion gradient. ( [] []) to [])  Gasses exerts Gasses exerts pressure, the amount pressure, the amount of of pressure each gas pressure each gas exerts exerts is called – is called – partial partial pressure (PO2 pressure (PO2 and PCO2) and PCO2) EXTERNAL RESPIRATION INTERNAL RESPIRATION
  • 18.  If PO2 differs across a membrane – oxygen will diffuse from a high to a low pressure. If PCO2 differs across a membrane – carbon dioxide will diffuse from a high to a low pressure. During inspiration the alveoli fills with air – higher PO2 and lower PCO2 than blood. Oxygen diffuse from alveoli into blood and carbon dioxide diffuse from blood into alveoli.
  • 19.  When blood reaches the tissue, cellular respiration in cells causes the tissue fluid to have a lower PO2 and a higher PCO2 than the blood. Thus oxygen diffuse from a high pressure in the blood to a low pressure in the tissue fluid and eventually in the tissue cells. Carbon dioxide diffuse from a high pressure in the tissue fluid to a low pressure in the blood.
  • 20.  Most oxygen is transported by hemoglobin (red pigment protein in erythrocytes). Oxygen combines with hemoglobin to form oxyhemoglobin. Hb + O2 = HbO2 Hemoglobin Oxygen Oxyhemoglobin A small amount of oxygen is transported in solution in the blood plasma.
  • 21.  Consist of 4 polypeptide chains (protein – 2 alpha and 2 beta). Each chain is associated with a heme group. Each heme group contains an iron atom. Iron binds with oxygen. Each red blood cell carries 250 million Hb molecules = 1 Billion Oxygen molecules
  • 22.  Most CO2 is transported as bicarbonate ions (HCO3-) HOW? FIRST CO2 binds with water to form carbonic acid (H2CO3) CO2 + H2O = H2CO3 Then carbonic acid dissosiates to form hydrogen and bicarbonate ions. H2CO3 = H+ + HCO3-
  • 23.  A small amount of carbon dioxide is transported by the Hemoglobin molecules in the form of carbaminohemoglobin (HbCO2). CO2 + Hb = HbCO2 The higher the amount of hydrogen ions in the blood the lower the pH. Therefor hydrogen ions bond with the globin part of Hb to keep the pH normal in the blood.
  • 24.  The following lower respiratory tract disorders are caused by exposure to infectious pathogens and / or polluted air, including tobacco smoke.  Pneumonia  Pulmonary Fibrosis  Pulmonary Tuberculosis  Emphysema  Bronchitis  Asthma
  • 25.  Alveoli fill with pus and fluid making gas exchange difficult X-ray of a patient with pneumoniaBacteria streptococcuscan cause pneumonia
  • 26.  Fibrous connective tissue builds up in lungs, reducing their elasticity and Oxygen diffusion.
  • 27.  Caused by a bacillus bacterium
  • 28.  Alveoli burst and fuse into enlarged air spaces. – Surface area for gas exchange is reduced.
  • 29.  Airways are inflamed due to infection (acute) or due to an irritant (Chronic). Coughing brings up mucus and pus.
  • 30.  Airways are inflamed due to irritation and bronchioles constrict due to muscle spasms
  • 31.  Smoking causes almost 90% of all lung cancers and is also a major cause of emphysema.Healthy normal Lung of alung of a non- smokersmoker
  • 32. Lung with largetumors causinglung cancer