Gas Exchange and Transport - Essay Example

Gas Exchange and Transport TAQ 440 words) Respiratory System Component Structure Function Nose and nasal cavity The nose is composed of muscle, bone, skin, and cartilage. The nasal cavity is a hollow space lined with little hairs and mucus membranes (Petechuk, 2012: p21). The nose provides protection and support for the nasal cavity. The hair and mucus in the nasal cavity filter air, trapping harmful particles (Petechuk, 2012: p21). Mucus in nasal cavity moisturizes incoming air. Pharynx Funnel-shaped, muscular organ divided into nasopharynx, oropharynx, and the laryngopharynx (Petechuk, 2012: p22). Funnels air from the nasal cavity into the respiratory tract (Petechuk, 2012: p22). Larynx Consists of the epiglottis that is a membrane flap The vocal folds The circoid and thyroid cartilage (Petechuk, 2012: p22). Vocal folds made of mucus membrane The thyroid and circoid cartilages protect and support the larynx and the vocal cords. Vocal folds tense and vibrate in order to create sound The epiglottis switches access between the trachea and oesophagus (Petechuk, 2012: p22). Trachea Long and tubular organ with a length of ~5 inches. Have C-shaped hyaline cartilage rings with ciliated columnar epithelium (Petechuk, 2012: p23). The C-shaped hyaline cartilaginous rings ensure the trachea is always open (Petechuk, 2012: p23). Ciliated columnar epithelium produces mucus to trap foreign particles, while the cilia conduct the mucus to the pharynx. Bronchi and bronchioles The bronchi have C-shaped cartilaginous rings and ciliated columnar epithelium Bronchioles have no cartilage, substituting it for elastin and muscle. They also have ciliated columnar epithelium (Jakab, 2010: p12) Rings of the bronchi ensure they are always open. The ciliated columnar epithelium produces mucus and uses ciliary movement to refine inhaled air further. Muscles in bronchioles enable them to control airflow into the lungs as required by varying activity levels, for example (Jakab, 2010: p12). Lungs These are cone shaped, concave organs Spongy texture Porous Highly elastic membrane Contains millions of alveoli with epithelial lining and surrounded by capillaries (Jakab, 2010: p13). The elastic membrane enables lungs to expand during inhalation The thin epithelium layer allows diffusion of gases between alveoli and erythrocytes (Jakab, 2010: p13) Muscles of respiration (diaphragm and intercostal muscles) The diaphragm is a thin, elastic sheet of muscle. Intercostal muscles span the ribs and are composed of external and internal layers, whose fibres run in opposite directions (Jakab, 2010: p14). The diaphragm’s elasticity allows it to contract and pull air into the lungs The internal and external intercostal muscles expand and contract alternately. Thus, contraction of external muscles and expansion of internal muscles raises the ribs and outwards, pulling air into the thoracic cavity (Jakab, 2010: p14). References Petechuk, D. (2012). The respiratory system. Westport, Conn: Greenwood Press. Jakab, C. (2010). The respiratory system. North Mankato, MN: Smart Apple Media. TAQ 2 a) (150 words) i. Breathing In Figure 1: Breathing in (tutorvista.com, 2014) When breathing in, as shown in figure 1, external intercostals contract, moving the sternum and ribs outwards and upwards and increasing chest width. Simultaneously, the diaphragm contracts and descends, increasing chest depth. Thoracic capacity increases, in turn reducing inter-pleural pressure, causing the elastic lung tissue to stretch and expand so as to fill the thoracic cavity (LeVert, 2012: p21). As alveoli air pressure falls below atmospheric pressure, air moves from the atmosphere into the alveoli. ii. Breathing out Figure 2: Breathing out (tutorvista.com, 2014) When breathing out, as in figure 2, external intercostals relax, moving the sternum and ribs inwards and outwards and reduce chest width. At the same time, the diaphragm relaxes and ascends, reducing chest depth. The thoracic capacity is reduced and inter-pleural pressure increases, causing the elastic lung tissue to recoil (LeVert, 2012: p22). This increases air pressure in the alveoli above atmospheric pressure, leading to air in the alveoli being forced out into the atmosphere. b) (150 words) Both lungs have ~300 alveoli each, which expand when air enters the lungs through the bronchi and bronchioles. Blood-filled capillaries surround these alveoli. Both the alveoli and the capillaries have one-cell thick membranes, which makes for a thin blood-air barrier between the interior of the alveoli and the blood (Fishman et al, 2011: p39). Thus, oxygen easily diffuses into the blood. Carbon dioxide produced by the body as a waste product is also transported by blood to the lung capillaries, where it flows into the alveoli by diffusion without facilitation. In this case, oxygen molecules are at a higher concentration in the alveoli compared to the lungs, while CO2 is at a higher concentration in the blood compared to the alveoli (Fishman et al, 2011: p39). This enables the flow of oxygen in inhaled air into the blood, while carbon dioxide in the blood flows into the alveoli. References Fishman, A. P., Geiger, S. R., Macklem, P. T., Mead, J. (2011). The respiratory system: The Mechanics of Breathing. Bethesda, Md: American Physiological Society. LeVert, S. (2012). The lungs. New York: Benchmark Books/Marshall Cavendish. tutorvista.com. (2014). Breathing Mechanism. Retrieved September 25, 2014, from http://www.tutorvista.com/content/biology/biology-ii/respiration/breathing-mechanism.php#inspiration-or-inhalation TAQ 3 (150 words) Figure 3: Regulation of breathing (lanecc.edu, 2013) As shown in figure 3, the activity of the external intercostal muscles, diaphragm, and respiratory muscles is regulated through nerve impulse transmission from the brain, specifically through the intercostal and phrenic nerves (Honda, 2012: p43). Respiratory depth and rhythm is essentially controlled in the pons and the medulla. Whereas the medulla sets the breathing rhythm through the self-exciting inspiratory centre, the pons centres smooth out these basic expiration and inspiration rhythms. It is these impulses between the medulla and the pons centres that maintain the human respiration rate per minute, which are ~12-15 inhalations/expirations. When one is engaged in a demanding physical activity, the brain respiration centres increase the rate of impulses sent to the muscles of respiration, enabling deeper and more vigorous breathing, in a process referred to as hyperpnea (Dempsey & Pack, 2011: p60). Still, physical activity does not always result in an increase in the breathing rate. References Dempsey, J. A., & Pack, A. I. (2011). Regulation of breathing. New York: M. Dekker. Honda, Y. (2012). Control of breathing and its modelling perspective. New York: Plenum Press. lanecc.edu. (2013). Regulation of Breathing. Retrieved September 25, 2014, from http://media.lanecc.edu/users/driscolln/RT127/Softchalk/regulation_of_Breathing/regulation_of_Breathing_print.html TAQ 4 (412 words) Disorder Cause Symptoms Interventions Prognosis Asthma Triggered by infections like flu, Also triggered by tobacco smoke, cold weather, allergens, and air pollution (Ganguly, 2014: p44) Frequent coughing Shortness of breath Chest pain or tightness Wheezing Asthma has no cure but can be managed Anti-inflammatory drugs reduce mucus production and swelling in airways (Ganguly, 2014: p44) Bronchodilator medication relax the airways, enabling air flow and improve breathing Asthmatic children can outgrow symptoms, while long-term anti-inflammatory medication may also make symptoms disappear forever (Ganguly, 2014: p44). However, it may still recur later in life in presence of a trigger Chronic obstructive pulmonary disease (COPD) Long term occupational exposure Tobacco smoke Pollution exposure Genetic risk factors Production of sputum Shortness of breath Wheezing Barrel chest and tripod positioning (Ganguly, 2014: p47) No known cure Supplemental oxygen, reduction of exposure to pollution, and cessation of smoking used to manage the disorder (Ganguly, 2014: p47) Non-invasive ventilation aids in breathing support Worsens with time and causes death Results in disability COPD worsening varies with presence of risk factors that predict poor outcome, such as obstruction of air flow and shortness of breath (Ganguly, 2014: p47) Aortic Aneurism Atherosclerosis Hypertension Local artery injury Bicuspid aortic valves at birth (Sutton, 2010: p19) Marfan Syndrome Aging Abdominal, chest, or back pains Pulsation in the naval region Endovascular or open surgery is the disorder’s definite treatment Strict control of blood pressure to decrease aneurysm expansion Use of occasional beta-blockers, statins, and smoking cessation enables management of the disorder in frail patients (Sutton, 2010: p19). Medical treatment of thoracic aorta gives a higher chance of survival than surgery, which increases risk of death to ~30% (Sutton, 2010: p19). Deep Vein thrombosis Prolonged sitting Being bed-ridden Localized trauma Obesity Pregnancy Sometimes has no symptoms (Sutton, 2010: p19) Swelling in affected leg Pain in the leg Anti-coagulants reduce and prevent clot formation Thrombolytics break up the clots Filters inserted into the vena cava prevent loose clots from reaching the lungs (Sutton, 2010: p19) Compression stockings prevent and manage leg swelling Usually disappears without major issues, but could return. Long term swelling and pain also persists in the elderly Clots in the thigh have a higher likelihood of accessing the lungs than those in the lower leg (Sutton, 2010: p19) References Ganguly, N. K. (2014). Studies on respiratory disorders. New York: Humana Press Sutton, A. L. (2010). Blood and circulatory disorders sourcebook. Detroit, MI: Omnigraphics. TAQ 5 (300 words) The main blood components of the blood are plasma, erythrocytes, leukocytes, and platelets. Plasma is the blood’s liquid component, in which the platelets, erythrocytes, and leukocytes, proteins, antibodies and salts are suspended. Albumin protein prevents leakage of blood into the tissues, while also binding and transporting such substances as some drugs and hormones (Taylor-Butler, 2012: p41). Finally, it also acts as a water reservoir for tissues, prevents collapse of blood vessels and maintains circulation and blood pressure, and regulates body temperature by carrying heat from core tissues to peripheral organs. Erythrocytes, on the other hand, contain haemoglobin that transports oxygen to the tissues for metabolic needs, while also carrying waste CO2 to the lungs for expulsion. In addition, they also release ATP, S-nitrosothiols, nitric oxide, and hydrogen sulphide when they undergo shear strength (Taylor-Butler, 2012: p42). These compounds relax and dilate blood vessels to promote normal or increased blood flow. Leukocytes are primarily responsible for offering defence against infections and there are 5 major types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Neutrophils are the most numerous and ingest fungi and bacteria, thus killing and digesting them. Lymphocytes are made up of T cells and natural killer cells that protect the body from viral infections and detect some cancer cells, as well as B cells that produce antibodies (Ring, 2013: p22). Monocytes ingest damaged or dead blood cells, while eosinophils are involved in allergic responses along with the basophils, cancer cell destruction, and killing of parasites. Finally, platelets are cell-like particles that aid in the process of clotting to prevent excessive blood loss. They gather and cluster at bleeding sites to form a clot or plug that seals the vessel. They also convert fibrinogen to fibrin, which traps blood cells, leading to coagulation, while summoning more platelets (Ring, 2013: p22). References Ring, S. (2013). Blood. Philadelphia: Chelsea Clubhouse Books. Taylor-Butler, C. (2012). The circulatory system. New York: Childrens Press. TAQ 6 1) See attached pdf file 2) (400 words) The heart contracts continuously and regularly so as to pump blood to the lungs and the rest of the body, which is the result of electrical impulses that are generated and conducted by cardiac cells. Cardiac conduction refers to the rate of electrical impulse conduction that result in relaxation and contraction of heart muscle (Peto, 2013: p51). This constant cycle of relaxation and contraction of heart muscle (cardiac cycle) causes pumping of blood in the body. Cardiac conduction occurs in four main phases. In stage one, the sinoatrial node contracts and generates nerve impulses, which travel across the wall of the heart and result in contraction of the atria. After these impulses reach the atrioventricular node, they are delayed for approximately 1/10th of a second, allowing the atria to contract and its contents to be emptied first. The impulses are then transmitted along the atrioventricular bundle, which branches into two bundles that carry impulses to the right and left ventricles. Finally, as the atrioventricular bundles divide to form Purkinje fibres at the heart’s base, the impulses cause the Purkinje fibres to trigger contractions in the ventricles’ muscle fibres, pumping blood to the pulmonary artery and the aorta (Peto, 2013: p52). Cardiac conduction is the force that drives the cardiac cycle. The cardiac cycle is made up of the diastole and systole phases. During the former, ventricles and atria are relaxed, allowing flow of blood into them, while, and in the latter, ventricles contract and blood is sent to the lungs and the rest of the body (Peto, 2013: p53). In the diastole phase, blood flows into the left and right atria and, as the valves between the ventricles and atria open, blood flows into the ventricles. The atrioventricular valves open as the sinoartrial node causes contraction of the atria, thus emptying blood into from atria into the ventricles. Blood flow-back is prevented by semi-lunar valves. During the systole phase of the cardiac cycle, there is contraction of the right and left ventricle that pumps blood out into the pulmonary artery and aorta respectively. During this process, the semi-lunar valves open and the atrioventricular valves close as the ventricles forcing blood out into either the aorta or pulmonary artery and preventing blood from flowing back into the atria (Peto, 2013: p53). When the heart is filled with blood and the blood is pumped out of the heart, this constitutes one cardiac cycle. References Peto, J. (2013). The heart. New Haven: Yale University Press. 3) (300 words) Blood vessel Structure Function Arteries The outer layer is composed of fibrous connective tissues that merge with loose connective tissue surrounding the arteries (Rogers, 2011: p37). Middle layer is composed of involuntary muscle and elastic connective tissue. It is also innervated to transmit nerve impulses The inner layer is composed of flat epithelial cells Carry oxygenated blood from the heart under high pressure, except for pulmonary arteries that carry deoxygenated blood to the lungs (Rogers, 2011: p37). Their contraction and relaxation ability enables control of blood pressure and volume Flat interior reduces friction as blood flows under high pressure (Rogers, 2011: p38) Veins Has three layers like the arteries Its middle layer, however, is thinner They also have semi-lunar valves (Rogers, 2011: p38). Conduct deoxygenated blood to the heart, except for pulmonary veins that carry oxygenated blood to the left atrium from the lungs (Rogers, 2011: p38) Carry waste products from tissues and organs, while the inferior vena cava also conducts digested food via the liver into the inferior vena cava. The semi-lunar valves in the veins prevent the blood from flowing back away from the heart, especially as it is under low pressure Capillaries They have an average diameter of 0.01 millimetres Their walls are also only made up of a layer of a endothelial cells, which makes them one-cell thick (Rogers, 2011: p38) The thin layer of the capillaries allow exchange of gases by diffusion between the blood in the capillaries and fluids of the tissue (Rogers, 2011: p38) The thin layer also enables exchange of nutrients and waste material via diffusion between the blood and the tissue fluids The thin diameter enhances blood pressure to quicken diffusion of nutrients and gases across its walls (Rogers, 2011: p38). References Peto, J. (2013). The heart. New Haven: Yale University Press. Rogers, K. (2011). The cardiovascular system. New York, NY: Britannica Educational Pub., in association with Rosen Educational Services. Read More