B Unit III Notes 6, 7 and 8

Transcription

1 The Respiratory System Why do we breathe? B Unit III Notes 6, 7 and 8 Respiratory System We know that our cells respire to produce ATP (energy). All organisms need energy to live, so that s why we undergo cellular respiration. Think about the cellular respiration equation. Based on this information there are two main requirements for organisms to have a respiratory system: a. Large Respiratory Surface b. Moist Environment Based on this, we breathe in Oxygen and breathe out Carbon Dioxide. This is known as gas exchange. The carbon dioxide must be able to leave out cells, and the oxygen must be able to enter our cells. This is done through the process of diffusion. In humans and most other organisms, the respiratory surface the lungs.

2 All lungs must have: a. b. c. Moist Surface Area Mechanism for air to come in contact with lung surface Circulatory system to carry gases between lungs and other cells There are many different versions of lungs exist depending on the organism. (Fig on page 335) We use our lungs to breathe. Breathing can be subdivided into inhalation/ inspiration (breathing in) and exhalation/ expiration (breathing out). The main parts of the respiratory system you need to know: a. b. c. d. e. Inhalation exchange of oxygen and carbon dioxide between blood and the cells of the surrounding tissue. Exhalation exchange of oxygen and carbon dioxide between blood and air. Nasal cavity Trachea Bronchi Bronchioles Alveoli

3 Pathway of a Breath of Air 1. Air enters via the nostrils or the mouth 3. Goes into the pharynx next, otherwise known as the throat 4. Next travels into the glottis, which is closed by the epiglottis when eating. 5. Passes over the larynx, otherwise known as the voice box, which holds the vocal cords. 2. Goes into the nasal cavity or oral cavity, depending on how it came in. Cilia in the nasal cavity help filter out dust (see figure 10.5 on page 336) Capillaries in your nasal cavity help warm and moisten the air. This is why breathing through your nose is the better option. 6. Goes into the trachea, otherwise known as the windpipe. This is supported by semicircular cartilage rings (see figure 10.7), and carries the air into the bronchi (plural of bronchus) 7. The bronchi carry the air into the lungs, and more specifically, into the smaller branches called bronchioles. 8. The bronchioles now carry air into the alveoli, which are moist sacs at the end of the tract where the actual gas exchange occurs. These are just one cell thick and are surrounded by capillaries.

4 Passageway of Air Breathing Mechanics There is one other major part of the respiratory system that deals with the breathing in particular. It is this part that allows you to yell really loud, or sing from the pit of your stomach. We are referring to the diaphragm. This is the large tissue that is found below your lungs. Inhalation Rib (aka intercostal) muscles and cage contract, moving up and out Diaphragm contracts and pulls down Air moves into the lungs due to the negative pressure created by the diaphragm moving down.

5 Exhalation Rib muscles and cage relax, moving down and in Diaphragm relaxes and pushes up to its regular state. This movement of the diaphragm causes air to be pushed out of the lungs, allowing them to deflate Notes 7 Lung Capacity Think about the difference between and normal breath, and a deep breath. When you are relaxed and breathing normally, your body doesn t use up the full capacity of your lungs. Obviously, as your body s needs increase, so does the amount of air drawn into your lungs (example: during exercise ) Page 340 for definitions

6 Tidal Volume = 500mL Vital Capacity = 4800 ml Inspiratory Reserve Volume (IV) = 3100 ml Expiratory Reserve Volume (EV) = 1200 ml Residual Volume = 1200 ml Respiratory Efficiency = 6000 ml SPIROGRAPH

7 Pneumonia Notes 8 Respiratory Disorders See page 343 for the four most common lung disorders. Occurs when the alveoli in lungs fill with thick fluid, making gas exchange difficult or even sometimes impossible Impairs the alveolis ability to produce O2, Can be treated with antibiotics Two main types: lobar and bronchopneumonia It is worth knowing what all the disorders are but for this course we will focus on 3: 1. Pneumonia 2. Asthma 3. Lung Cancer Asthma A chronic obstructive disease that is characterized by extreme sensitivity of the lungs (due to various triggers see figure 10.7 on page 346) that cause the airway to react and become obstructed (due to inflammation) Lobar affects the lobe of ONE lung only, while bronchial affects patches throughout BOTH lungs. Usually caused by infection due to bacteria or viruses. Asthma Bronchioles also constrict due to the associated muscle spasms, making breathing even more difficult. Effects vary from mild to severe and around ¼ people affected by asthma as a child will outgrow it by adulthood. Symptoms usually occur in episodes called an asthma attack. During an attack three (3) main things happen: Airway swells Bronchial muscles tighten Mucous secreted into airway Can be treated by various medications (eg inhalers/ puffers)

8 Lung Cancer Lung Cancer Leading cancer killer in North America As the carcinoma (malignant tumor) grows, the abnormal cells multiply and take over the healthy tissue in the lungs. 87% of lung cancer cases have been confirmed to be caused by smoking. This is because a lot of substances in tobacco smoke cause cancer, which we call carcinogens. (This stat also includes second hand smoking) Can also be caused by exposure to radon Smokers lungs another image on page 344 Refers to the uncontrolled and invasive growth of abnormal cells in the lungs Lung Cancer Symptoms include: Chronic cough Coughing up blood Weight loss / loss of appetite Shortness of breath Chest pain fever Lung Cancer Treatment varies depending on how far the disease has spread: If caught in the early stages: surgery to remove the tumor If the disease has already progressed chemotherapy or radiation

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