RESPIRATORY SYSTEM
Figure 6.1 Differences between Respiration (Animals) and Photosynthesis (Plants)
Nasal & Bucal Cavity - Where air enters the body
Pharynx - Throat
Larynx - Voice Box
Epiglottis - Flap of skin to make materials go in the correct tubes (food/water in esophagus, air in trachea)
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Introduction
Energy is locked up in food molecules such as glucose. Living organisms release energy by consuming these molecules and breaking them down. In all living organisms, food molecules are broken down by a reaction called oxidation.
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Oxidation - A chemical reaction in which a molecule gains oxygen or loses hydrogen (Refer to redox reactions in MYP Chemistry).
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Cellular Respiration - Actual respiration (the oxidation of food substances with the release of energy in living cells), breakdown of glucose in the mitochondria to make ATP.
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Respiration System - Organs in animals that exchange gases with the environment
Gas exchange between oxygen & carbon dioxide
needed
waste
Diffusion of Gases through Skin
- Low metabolic rate because respiration is directly proportional to metabolism. Diffusion takes time through skin due to the low concentration gradient, resulting in low metabolism
- Only in aquatic animals
- Water provides a better concentration gradient to be maintained for longer
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Specialized Structures
1. Gills - Aquatic animals (take in water, diffuse oxygen, get rid of water)
2. Spiracles - Insects (Through body, take oxygen throughout body)
3. Lungs - Terrestrial Vertebrates (most of them)
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Counter current Exchange
Urine flows in one direction, while blood flows in the other direction throughout the body. Results in a constant gradient being maintained
Blood
Urine
Aerobic & Anaerobic Respiration
Aerobic Respiration - The breakdown of food substances in the presence of oxygen with the release of a large amount of energy. Carbon dioxide and water are released as waste products.
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Anaerobic Respiration - The breakdown of food substances in the absence of oxygen, releasing less energy than aerobic respiration
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Anaerobic respiration is mainly used by microorganisms that live in areas where there is little to no oxygen. However, many organisms that respire aerobically can respire anaerobically as well.
Yeast
E.g. in the presence of oxygen, yeast will respire aerobically and produce carbon dioxide, water and large amounts of energy. But, in an oxygen deficit atmosphere, yeast will produce ethanol (a type of alcohol), carbon dioxide and energy (less than in aerobic respiration).
The excess energy is trapped in the ethanol, but without oxygen the yeast is unable to break it down further.
The process of creating alcohol is through anaerobic of respiration.
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Energy Conversion in Muscle Cells
During vigorous muscular contractions/exercise, your muscles will first respire aerobically (this is why you start panting heavily to remove carbon dioxide quicker and take in more oxygen), however after maximum aerobic respiration is unable to produce enough energy to meet the demand, the muscles start to respire anaerobically to create extra energy. In the process, lactic acid is formed. The equation is
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Since there is insufficient oxygen to meet the demands of vigorous muscular contractions, the muscles incur an oxygen debt, and lactic acid slowly builds up in the muscles (after a lot of lactic acid builds up it causes fatigue and muscular pains). When the body eventually rests, the breathing rate will continue to be faster for some time to provide enough oxygen to repay the oxygen debt. Lactic acid is also gradually removed from the muscles and transported to the liver where the remaining lactic acid is transformed into glucose.
Trachea
- Produce mucus constantly (trap inhaled particles)
- Cilia Lining (Refer to Cells): Constantly moving up to take away inhaled particles away from lungs to towards the mouth to the GI tract to dissolve it
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Bronchi (Sing. Bronchus)
- Two Bronchi (left and right)
- Bronchi separate into bronchioles
- At the end of each bronchiole is a sack of alveoli surrounded by cappilarries
Alveoli
- Lungs have single cell thick alveoli
- Moist, thin walled packets
- Alveolus (singular)
- Oily surfactant prevents the alveolar walls from collapsing and sticking together; also traps bacteria if all defense mechanisms of lungs fail
- Walls of capillaries and alveoli share same membrane (diffusion made easier)
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Diaphram
- Thick muscles separating digestive and respiratory system
- Relax (volume of long decreases; air goes out) and contract (volume of lung increases; air rushes in) -> antagonistic muscles
- The intercoastal (internal and external) muscles line the ribs.
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*If external muscles relax, diaphram relaxes, breathe out
*If external muscles contract, diaphram contracts, breathe in
How is CO2 removed from your lungs?
Figure 4. Diagram of an alveolus
1. Tissue cells produce CO2 during aerobic respiration
2. CO2 diffuses from tissue into capillaries into RBCs.
3. CO2 reacts with water in RBCs to form carbonic acid (catalysed by enzyme carbonic anhydrase - present in RBCs)
4. Carbonic acid is converted to hydrogencarbonate ions which diffuse out of the RBCs. Most of CO2 is carried in blood plasma as hydrogencarbonate ions.
5. In lungs, the ions diffuse back into the RBCs where they are converted to carbonic acid, and then back into water and CO2.
6. The CO2 diffuses out of the blood capillaries into the alveoli, where it is expelled into the atmosphere when you breathe out.
Diseases
External Nostrils
Nasal Passages
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
Smoking tobacco
Nicotine - Increases heartbeat rate and blood pressure, increases risk of blood clots in the arteries - leads to increased risk of coronary heart disease
Carbon monoxide - Reduces ability of blood to carry oxygen, narrows lumen of arteries & increase in blood pressure
Tar - Increases risk of cancer in lungs, dust particles trapped in air passages cannot be removed due to cillia being paralyzed, increased risks of chronic bronchitis and emphysema
Irritants - Dust particles in air passages cannot be removed, increased risks of chronic bronchitis and emphysema
Chronic Bronchitis
- Due to prolonged exposure to irritant particles
- The epithelium lining of the air passages become inflamed
- Excessive mucus is secreted by the epithelium
- The cilia on the epithelium are paralyzed; mucus and dust particles cannot be removed
- Air passages become blocked, breathing becomes difficult
- Persistent coughing, leads to an increased risk of getting lung infections
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Emphysema
- Persistent and violent coughing due to bronchitis may lead to emphysema
- Oily surfactant no longer on alveoli, causes them to become dry and brittle (easily breakable)
- The partition walls between the alveoli break down due to persistent and violent coughing
- This results in a decreased SA:V for gaseous exchange
- Lungs lose their elasticity and become inflated with air
- Breathing becomes difficult, wheezing and severe breathlessness result
- When a person has chronic bronchitis and emphysema, s/he suffers from chronic obstructive lung disease.
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Lung Cancer
- Risk of lung cancer increases when a person smokes tobacco
- Cancer is the uncontrolled division of cells producing outgrowths or lumps of tissues.
