Respiratory System - Assignment Example

Respiratory System Q1. Respiration and ventilation Ventilation describes inspiration and expiration while respiration describes how gases are exchanged between alveoli and the blood, and also between the cells and the blood. In simple terms, respiration entails all aspects of breathing. Both respiration and ventilation are crucial in an organism. However, ventilation entails constant process of taking in oxygen and taking out carbon dioxide. Respiration, on the other hand, involves the breakdown of oxygen by the body to enhance easier use by the body. Ventilation is purely physical process while respiration can be regarded as a chemical process. Ventilation takes in oxygen into the lungs and respiration supplies this oxygen into the body through the blood stream. Ventilation is voluntary while respiration is involuntary. Ventilation is, therefore, a component of respiration (Tortora & Derrickson 2009, p. 920-930). Respiration refers to the process used by organisms in exchanging gases with the environment, and it entails the use of oxygen and elimination of carbon dioxide. Oxygen and carbon dioxide are the two gases that are most in both ventilation and respiration. Respiratory system comprises of the nasal passages, larynx, the pharynx, the trachea, bronchi and the lungs. On the other hand, ventilation describes the inhalation and exhalation processes. It refers to breathing process. In inhalation, lungs are inflated with air that brings oxygen into the body and during exhalation, lungs releases carbon dioxide into the environment. The respiratory system organs ensure entry of oxygen into the body and release of carbon dioxide out of the body. Inhalation and exhalation involve conducting air towards or away from lungs through a series of some cavities, openings and tubes (Michael & Albert 2001, p.10-13). Structures of the respiratory system and their adaptation to ventilation Respiratory tract The coarse hair, mucus and cilia in the respiratory tract clean, warms and moistens the air. Hair is in the nostril region while mucus and cilia are found in the rest of the nasal cavity. Hair and cilia in the nose are used in screening air while in trachea cilia moves upward and carry the food particles in the pharynx. The heat given by the blood vessels warms the air while the wet surfaces moisten the air. As air moves out during exhalation, it cools and dries up. During cooling, moisture is deposited on lining of the nose and the trachea (Michael & Albert 2001, p.10-13). Nose Nose opens at the nostrils which lead to nasal cavities. Nasal cavities contain ciliated cells that act as the odour receptors. The cells contain nerves that lead to the brain. Nasal cavities communicate with cranial sinuses in the skull. Any inflammation of the duct stimulates accumulation of fluid. The hollow spaces in the nose enhance filtering, warming and moistening the air (Michael & Albert 2001, p.10-13). Pharynx Pharynx is funnel-shaped and links oral and nasal cavities to larynx. Tonsils in the pharynx contain lymphocytes that protect against inhaled foreign antigens. Larynx Larynx acts as air passage between the pharynx and trachea. Larynx moves up against epiglottis when swallowing food; the flap tissue prevents food from entering into the larynx. Alveoli Alveoli are contained in the lungs, and each sac is surrounded by the blood capillaries. The walls of alveoli contain the squamous epithelium or the flattened cells that enhance the exchange of gases. The surfactant in the alveoli reduces the surface tension and prevents lungs from closing. During inhalation, the air moving in and out, tidal volume, is small. The vital capacity can be increased through expansion of the chest and lungs. During inspiration, external intercostal muscles and the lungs will contract. Diaphragm is dome shaped, and it will lower and contract during inhalation. The volume of the thoracic cavity increases, lungs expand, and the pressure in the alveoli decreases. This allows air to floe naturally flows outside the body (William, Frank & Victor 2007, p. 15). In exhalation, diaphragm is pressed up; rib cage moves downwards and the alveoli are prevented from collapsing by the surfactant. The intercostal muscles contract forcing rib cage move inward and downward during deep breathing. The contraction of the abdominal muscles pushes on the diaphragm increasing the thoracic cavity. This expels air out of the body (Tortora & Derrickson 2009, p. 920-930). Q2. Conditions for effective gaseous exchange Gaseous exchange takes place in the lungs. Effective gaseous exchange requires that the air sacs be of large surface area. The alveoli are bunched together to increase the surface area for the diffusion of the gases. Small surface area lowers the level of the intake of oxygen and the supply of oxygen to the muscles. The cell wall should be thin to allow quick diffusion to take place. The epithelial cells in alveoli and the capillaries are flattened and one cell thick. Also, the distance between alveoli and the capillaries is thin. This allows gases reach the blood vessels and bind with haemoglobin at a faster rate (William, Frank & Victor 2007, p. 15). The area should be moist to enhance solubilisation of the gases for easier diffusion across the membrane. The two gases, oxygen and carbon dioxide will dissolve in this membrane, and this enhances easier transportation since water can easily diffuse in and out of alveoli. Water contains a soapy surfactant that reduces surface tension and prevents collapsing of the alveoli. There should be a steep concentration gradient for the gases. Gases move from high to low concentration always. The gradient is maintained by the flow of the blood on one side and air on the other side. Oxygen diffuses down the concentration gradient from air into the blood while carbon dioxide diffuses out (William, Frank & Victor 2007, p. 15). The pleural fluid moistens the lungs and enhances flexibility. The alveoli should have a large surface area to enhance exchange of gases. The level of oxygen in the body should exceed that of carbon dioxide to maintain homeostasis and balance in the respiratory system. The alveoli in the lungs should be many to enhance maximum gaseous exchange (Gary & Kevin 2007, p.16). Q3. Role of the nervous system in generating normal breathing rhythm The nervous system coordinates and controls activities in the body through transmission of signals to and from the brain to signals to the various body parts. The neurons conduct the impulses between peripheral and the central nervous system. The glial cells surrounding the neurons enhance the signal transmission. Sensory neurons transmit stimuli from the nose to central nervous system. Brain will in turn process the stimuli and send the message back to the other parts of the respiratory system, and this triggers a reaction to the stimulus. Neurons use electrochemical neurotransmitters to transmit impulses among the other neurons (Tortora & Derrickson 2009, p. 920-930). The heart is unable to keep constant beating rhythm, but it can contract on its own accord. As a result, the nervous system has to come into play. Impulses from the brain control the rate of heart beat. Slowing down of heart rate depends on the need at a certain time. Brain composes of three parts, the cerebrum, cerebellum and brain stem. The medulla oblongata form lower section of the brain stem, and it forms the main controlling area for breathing. Pons and midbrain controls autonomic functions that transports nerve signals. Autonomic nervous system coordinates the blood pressure, the heart rate, breathing rate. The inspiratory and expiratory neurons maintain normal breathing rhythm. Inspiratory neurons become active during inspiration and inactive during expiration while expiratory neutrons are active during expiration and inactive during inspiration. Neutrons are sent to intercostals muscles and the diaphragm with messages that enhance contraction and relation at regular intervals (Michael & Albert 2001, p.10-13). Central receptors and peripheral chemoreceptors are two types of verves that control the level of oxygen in the blood. Central receptor is found in the medulla. When there is a decrease in oxygen, the message is sent to the respiratory center by the nerves to increase the breathing rate and the depth of breathing. The two receptors censor the carbon dioxide. The central receptor monitors the carbon dioxide levels in the cerebrospinal fluid. This surrounds the brain and spinal cord. Increased levels of carbon dioxide trigger the receptors that send the impulses to respiratory centre so as to increase the rate of breathing and allow diffusion of more oxygen in the blood and carbon dioxide out through the capillaries (William, Frank & Victor 2007, p. 15). Breathing is an involuntary action. Breathing is usually controlled by central nervous system that works together with peripheral nervous system. Sympathetic Nervous System controls the activity of certain systems in the body. It avails oxygen into the body muscles during exercises. This increases the heart beat and the breathing rate. Parasympathetic Nervous System lowers the heart beat after exercises and enables heart beat return to its normal rate. The automatic nervous system controls the breathing rate (Tortora & Derrickson 2009, p. 920-930). The sensor that controls the breathing rate is located in the aortic arch which is near the heart and the left lung. The sensor detects low or high oxygen or carbon dioxide levels during breathing and sends signals to respiratory centre within the brain that responds accordingly. The response can trigger increased breathing rate that is controlled by the sympathetic nervous system, or it can slow the rate of breathing using the parasympathetic nervous system. The nervous system transmits information to the brain at a rate of 20 times per minute irrespective of the changes in the levels of oxygen in the blood. This enhances a typical breathing rate. Neurons refer to special cells that transmit information to the respiratory system from the brain. Information is passed by the neurons from the brain through the spinal cord and back to the brain. Brain and spinal cord form the central nervous system (Tortora & Derrickson 2009, p. 920-930). The pathways for the nerves branch throughout the body forming the peripheral nervous system. Medulla oblongata is reached by neurons, after which they pass information to the Pons. The information is passed back to the medulla oblongata, through the spinal cord into the peripheral nervous system that carries out the response required. During breathing, diaphragm is supplied with the spinal nerves, C3-C5 while the intercostals muscles have the spinal nerves T1-T12. The signals sent by the CNS causes the contraction of respiratory muscles at specified intervals thus controlling the rate of breathing. During conscious breathing, cerebella cortex overrides the respiratory system (Michael & Albert 2001, p.10-13). Normally, the chemicals sent by the hormones to the blood affect the breathing rhythm. The heart can beat at a faster rate or slower rate based on the stimulation of the heart by the nerves. Acetylcholine chemical slows the heart rate. The chronic nervousness may elevate the heart rates for long periods due to anxiety. Also, environmental factors may alter the rate of heart beat; hence the normal breathing rate is affected. Any change in the environment triggers the CNS to send messages to the medulla, and the response may be increased or slowed down heart rates (William, Frank & Victor 2007, p. 15). References List Gary, T., & Kevin, P. (2007). Anatomy & Physiology of Breathing. p.16. Michael, P., & Albert, J. B. (2001). Physiology of Respiration. p.10-13. Tortora, G. J., & Derrickson, B. (2009). Principles of anatomy and physiology. Hoboken, NJ, John Wiley & Sons. pp. 920-930. William, M., Frank, K., & Victor, K. (2007). Exercise Physiology, Energy, Nutrition & Human Performance. p. 15. Read More