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Gas Exchange. By: An indian and a jew. How it all started. Respiratory structures are adapted for gas exchange in air or water. External Gas exchange, creature uses their body surface for gas exchange Gills are adapted for respiration in water

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gas exchange

Gas Exchange


An indian and a jew

how it all started
How it all started

Respiratory structures are adapted for gas exchange in air or water.

  • External Gas exchange, creature uses their body surface for gas exchange
  • Gills are adapted for respiration in water
  • Trachea and lungs are adapted for terrestrial respiration

All respiratory systems must be:

(1) Moist


(3)Large in relation to the body.

cellular respiration
Cellular Respiration
  • Cell respiration releases energy in the form of ATP so that this energy can be used inside the cell.
  • Cell respiration occurs in the mitochondria and cytoplasm of cells.
  • Oxygen is used in this process and carbon dioxide is produced.
external gas exchange
External Gas Exchange
  • Small animals with a large body surface use this and exchange gas externally
  • Is not very efficient but is good enough to support small animals.
  • Hydras and worms use this.
fish lungs a k a gills
Fish Lungs A.K.A Gills
  • Gills are outward extensions of the pharynx
  • Adapted by marine animals for gathering oxygen in water.
  • Fish use Countercurrent exchange-O2 rich water goes in the opposite direction of O2 poor blood.
  • Concurrent Exchange- O2 rich water goes in the same direction as O2 poor blood.
  • Countercurrent Exchange is more effective in extracting H2O.
  • Uses much more energy than lungs.
tracheal system
Tracheal System
  • Tracheae- Tiny air tubes that take oxygen directly to the cells.
  • Tracheoles- tinnier air tubes that branch off from Tracheae
  • Walls lined with chitin for support.
  • Used by bugs and other small terrestrials.
  • Not very efficient
  • It is fairly effective and costs very little energy to operate since oxygen is abundant in the air
  • Uses some muscles and pressure to easily manipulate gases.
  • Actually has more surface area than most body parts.
  • Is controlled by the brain.
some words you need to know
Some words you need to know.
  • Respiration- The sequence of events that result in gas exchange between the body’s cells and the environment.
  • External Respiration- The gas exchange between the air and the blood within the lungs. Blood transports oxygen from the lungs to the tissues.
  • Internal Respiration- The gas exchange between the blood and the tissue fluid. Blood then transports CO2 to the lungs.
  • Ventilation- The inspiration and expiration of air. The exchange of gas between the lungs and the atmosphere. (A.K.A Breathing)
  • Inspiration-The act of moving air into the lungs.
  • Expiration-The act of moving air out of the lungs.
  • The Nasal Cavity takes in air.
  • The pharynx filters, warms, and moistens air and conducts it into the lungs.
  • Air goes to the glottis (when the epiglottis is closed), then to the larynx, and then into the trachea.
  • Then it splits into 2 Bronchi which enter the Lungs, and then they split into many bronchioles with alveoli at the ends.
  • There is a huge capillary network in the lungs that surrounds the alveoli for gas exchange.
  • Blood delivers the oxygen to the tissues and bring back CO2 to lungs.

It is involuntary and the respiratory centers in the medulla oblongata control it. Can be influenced by nervous and chemical input.

respiratory centers
Respiratory Centers
  • Is located in the medulla oblongata and controls respiration.
  • It is sensitive to H+. When the pH decreasesfrom an increase in H+ it increases our breathing rate.
  • It detects H+ through receptors in the body.
  • Chemoreceptors called Carotid bodies (Carotid arteries) and Aortic bodies (Aorta).
  • It is a horizontal muscle that divides the thoracic cavity from the abdominal cavity.
  • Inspiration- It contracts and goes down and the chest moves up.
  • Expiration- It relaxes and goes up and the chests moves down.
  • Plays an important function in maintaining pressure in the lungs.
ventilation cont
Ventilation Cont.…


  • The external intercostal muscles contract. This moves the ribcage up and out. 
  • The diaphragm contracts. As it does so it moves down and becomes relatively flat. 
  • Both of these muscle contractions result in an increase in the volume of the thorax which in turn results in a drop in pressure inside the thorax.
  • Pressure eventually drops below atmospheric pressure. 
  • Air then flow into the lungs from outside the body, through the mouth or nose, trachea, bronchi and bronchioles. 
  • Air continues to enter the lungs until the pressure inside the lungs rises to the atmospheric pressure.
ventilation cont1
Ventilation Cont.…


  • The internal intercostal muscles contract. This moves the ribcage down and in. 
  • The abdominal muscles contract. This pushes the diaphragm up, back into a dome shape. 
  • Both of these muscle contractions result in a decrease in the volume of the thorax. 
  • As a result of the decrease in volume, the pressure inside the thorax increases. 
  • Eventually the pressure rises above atmospheric pressure.
  • Air then flows out of the lungs to outside of the body through the nose or mouth. 
  • Air continues to flow out of the lungs until the pressure in the lungs has fallen back to atmospheric pressure.
  • (Breathing)
why you need to ventilate
Why you need to Ventilate
  • To maintain the concentration gradients of oxygen and carbon dioxide in the alveoli. 
  • The body needs oxygen to make ATP via cell respiration.
  • The body needs to get rid of carbon dioxide, a product of cell respiration.
  • Oxygen needs to diffuse from the alveoli into the blood. Carbon dioxide needs to diffuse from the blood into the alveoli.
  • To do so there must be a high oxygen concentration and a low carbon dioxide concentration in the alveoli. 
  • A ventilation system makes this possible by getting rid of the carbon dioxide in the alveoli and bringing in more oxygen.
gas exchange1
Gas Exchange
  • Gas exchange is the biological process of swapping one gas for another. (What happens in the alveoli)
  • Oxygen diffuses into the capillaries from the air in the alveoli and carbon dioxide diffuses out of the capillaries and into the air in the alveoli. 
  • It occurs in the alveoli in the lungs.
  • Gases have partial pressures, which exert pressure on other things.
alveoli and their special features
Alveoli and their Special Features
  • Great numbers of them increase the surface area for gas exchange.
  • Wall made up of single layer of cells and so are the walls of the capillaries so diffusion distance is small allowing rapid gas exchange. 
  • Covered by a dense network of capillaries which have low oxygen and high carbon dioxide concentrations. This allows oxygen to diffuse into the blood and carbon dioxide to diffuse out of the blood.  
  • Some cells in the walls secret fluid allowing gases to dissolve. The fluid also prevents the sides of alveoli from sticking together.
reactions with hemoglobin
Reactions with Hemoglobin
  • Hemoglobin (Hb)-A special molecule that has a special part in aiding our breathing. Commonly forms bonds with oxygen and CO2
  • Oxyhemoglobin (HbO2)-Used by RBCs to carry oxygen. (Common)
  • Carbonic anhydrase- is an enzyme that speeds up the breakdown of carbonic acid and the formation of bicarbonate ions.
  • Bicarbonate ion (HCO3-)-The from in which Carbon is transported in the blood. (common)
  • Carbaminohemoglobin(HbCO2)-Some carbons from bonds with hemoglobin to form this. (Rare)
  • Reduced hemoglobin-(HbH+)- maintains your body’s ph.
  • Exhale:HbO2 separates when blood reaches the tissues where it diffuses and releases the oxygen. The CO2 then either attaches to the Hb and forms HbCO2 or CO2 combines with water to form Carbonic acid (H2CO3) which dissolves into H+ and a Bicarbonate ion (HCO3-).
  • Inhale: The H+ and HCO3- combine into carbonic acid and form water and CO2, which is catalyzed by carbonic anhydrase, and is then expired. The O2 comes in and forms HbO2 with the Hemoglobin.
bohr shift
Bohr Shift
  • Bicarbonate Ion- HCO3- acts as a buffer so the blood will not get too acidic.
  • The reaction is reversed when the blood reaches the lungs.
  • Bohr Shift: The more CO2 in the blood, the more acidic (low pH) the blood becomes. Decreasing the pH causes hemoglobin to release its’ oxygen easier. This is needed during exercise to supply the body with O2.
dangerous stuff bro
Dangerous Stuff Bro…
  • Bronchitis-Infection of the Bronchi, treatable.
  • Pneumonia- Your lungs are filled with bacteria due to an infection, treatable.
  • Pulmonary Tuberculosis- Caused by tubercle bacillus(a bacterium), treatable.
  • Carbon Monoxide (CO)-poisonous because it forms strong bonds with Hemoglobin and is difficult to remove, incurable.
  • Asthma-disorder caused by really sensitive airways, causes spasms, incurable, treatable.
  • Emphysema-Damaged alveoli cause lack of oxygen, incurable, harmful.
  • Lung Cancer=Some bad cellsTumorMetastasis GG.
  • Smoking=BAD