The Mechanism of the Respiratory System - Essay Example

?Question The respiratory system cannot work without the help of the cardiovascular system. The mammalian heart has double circulation. These two circulations are concerned with oxygenated and deoxygenated blood. The right ventricle pumps the deoxygenated blood towards the lungs via the pulmonary artery. This blood is coming from the respiring tissues of the body, which means it is rich in CO2, which is then converted into hydrogen carbonate ions and carried towards the alveolus of the lungs. Here the exchange between oxygen and carbon dioxide takes place. Since CO2 has a higher concentration in the blood than in the alveolar cavity, a diffusion gradient is formed, causing the CO2 to move out of the blood and then exhaled. There is a higher concentration of O2 in the alveolar cavity than in the blood entering the capillary network. Oxygen dissolves in the film of water found on the surface of the alveolus and then this dissolved oxygen diffuses across the epithelial cells of the alveoli and the capillaries into the blood plasma. This oxygen diffuses into the red blood cells, where it combines with hemoglobin to form ox hemoglobin. (Gillian Pocock, 2006) This oxygenated blood flows back into the left atrium via the pulmonary vein where the heart will pump the blood around the body again to supply oxygen to the respiring cells, thereby completing the second part of its circulation. Without the proper functioning of the cardio vascular system, the lungs will be unable to perform their primary function, i.e. to convert deoxygenated blood into oxygenated blood. References Gillian Pocock, C. D. R., 2006. Human physiology: the basis of medicine. 3, illustrated ed. s.l.:Oxford University Press. Question 2-Homeostasis: Negative feedback is a mechanism used to bring the system back to its normal state by triggering a counter response. The negative feedback mechanism in all living things is homeostasis. This mechanism helps to control and regulate the internal environment of any organism. The internal environment of any multi cellular organism is tissue fluid that bathes the body cells. Keeping the conditions of the tissue fluid such as its pH temperature and salt content at relatively constant levels is called homeostasis. Example 1: One of the examples of the negative feedback mechanism is the regulation of blood glucose levels. The normal blood glucose level is 90mg/100cm3 of blood. In the pancreas there are special cells called islets of Langerhans that respond to the glucose levels in the blood. Alpha cells of the pancreas detect low blood glucose levels and the beta cells detect high blood glucose levels. Alpha cells respond by secreting glucagon that converts glycogen in the liver into glucose. Glucagon increases blood glucose levels by increasing the break down of glycogen into glucose, and by making sure that more glucose is released form the liver. While the beta cells respond by secreting insulin that causes the liver to increase the amount of glucose converted into glycogen and start storing it. Beta cells also increase the rate at which glucose is transported to target cells, and increases its utilization in ATP-synthesis .These are self-regulatory negative feedback mechanisms thus causing the blood glucose levels to return back to normal. (Chiras, 2011) Example 2: The regulation of body temperature is also achieved by homeostasis. The changes in the external environment are detected by nerve endings in our skin and the nerve impulses are sent to the hypothalamus. The hypothalamus is the part of the brain that acts as a control center. If there is an increase in temperature, the hypothalamus will then send nerve impulses to the sweat glands of the body to cause more sweat to reach the sweat ducts, and as the sweat reaches the sweat pores it evaporates causing the body to cool down as the latent heat is given off to the environment. The arteries dilate as well and more blood flows into the capillary networks as a result more heat is lost to the surrounding. As a result the body temperature return backs to normal. An Opposite effect occurs if the temperature of the surroundings lowers. (Frederic P Miller, 2009) References: Chiras, D. D., 2011. Human Biology. s.l.:Jones & Bartlett Learning. Frederic P Miller, A. F. V. J. M., 2009. Homeostasis. s.l.:VDM Publishing House Ltd.. Question 3(Membranes): Passive transport includes all the other processes in the list. These processes occur as a result of differences in the concentration of substances, inside and outside, which is also known as the concentration gradient. The term “concentration gradient” means the difference in concentration between the two regions. Because substances can diffuse down the concentration gradient, they do not require energy for this movement. I.e. unlike active transport they do not require chemical energy, as this movement is a spontaneous process. (Tortora, 2004) Diffusion of a solute across a membrane. Diffusion is the spontaneous movement of particles to fill a given space uniformly. And the particles are going to move form an area of high concentration to an area of low concentration i.e. down the concentration gradient, until the concentration is the same throughout. The steeper the gradient the faster is going to be the rate of diffusion. This movement of particles does not require any energy. (Bailey, n.d.) Osmosis is a special type of passive diffusion in which water molecules move from an area of high water potential to an area of low water potential (high to low concentration) through a partially permeable membrane. For example: absorption of water into the root hair cells of a plant occurs through osmosis. Facilitated diffusion is another type of passive transport mechanism that allows molecules or particles to travel across membranes with the aid of special transport proteins. Some molecules are unable to diffuse through the lipid bilayer of membranes for examples, sodium ions, chloride ions and glucose. Ion carrier proteins and channel proteins are fixed in the cell membranes, which allow these molecules and ions to be transported into the cell. The opening and closing of the ion passage ways are controlled by the cell itself. The carrier proteins, bind to the specific molecules, change their shape and then dump them into the cell. The transport of ions down an electro chemical gradient or chemiosmosis is the movement of ions down an electrochemical gradient through a selectively permeable membrane. It is related to the movement of hydrogen ions from a region of higher concentration to a region of lower concentration, generating ATP in the process. This, again, is a passive process, not requiring any form of energy for the movement. References: Bailey, R., n.d. Diffusion and Passive Transport. About.com. Tortora, G. J., 2004. Principles of human anatomy. s.l.:John Wiley & Sons. Question 4: (a) In the mammalian circulatory system the blood flows from a region of higher pressure to a region of low pressure. If there was no difference in pressure, the blood would be unable to flow to the various regions of the body, i.e. lungs, liver, abdomen, etc. Thus, the flow of blood is as a result of changes in pressure. Mammals have double circulation, which means that during one circulation the blood passes twice through the heart. This would enable blood pressure to be maintained. These two circulations are known as pulmonary and systematic circulation. Having a double circulation is an advantage because the oxygenated and de-oxygenated blood is not allowed to mix and as a result the person stays active. In this type of circulation, blood is pumped for the second time after it loses pressure in the capillary bed of the lungs. Therefore, via double circulation, pressure is restored after blood has passed through the lung capillaries. (Toby Fagan, 2002) The heart is divided into four chambers, two upper atrial chamber and two comparatively thicker walled lower ventral chambers. These chambers are divided from the center into the left and right parts, via the septum. The right and the left sides of the heart consist of separate valves and arteries, specific to the pulmonary and systematic circulations. When the atrium of the heart contracts the blood enters the left ventricle. The walls of the left ventricle are thicker than that of the right ventricle because of the greater pressure with which it has to pump the blood. That is, its job is to pump the blood to the rest of the body via the aorta. This is one of the reasons why the walls of the aorta are also very thick. As the left ventricle fills up with blood the pressure in the chamber increases and at one stage the walls of the atrium form another pressure and as it contracts the pressure causes the bi-cuspid valves to open and blood would enter into the left ventricle. As more and more blood enters into the left ventricle, the walls of the ventricle create another pressure opposite to the blood pressure and this causes the bi-cuspid valves to close and the semi-lunar valves to open. Now the blood enters into the main aorta and from there it circulates throughout the body. Later, de-oxygenated blood from the superior and inferior vena cava is carried to the right atrium and then the blood circulation continues. (Noble, 2005) The pulmonary circulation is concerned with the heart and lungs. The pulmonary artery and the pulmonary vein are the only two blood vessels involved in this circulation and a as result of this circulation, the de-oxygenated blood gets oxygenated as it goes to the lungs for gaseous exchange. When right atrium contracts the blood is entering via the tri-cuspid valves into the right ventricle an then the right ventricle contracts , the semi-lunar valves open and the tri-cuspid valve closes and as a result of this, blood would be entering into the pulmonary artery. After the blood gets oxygenated, it enters into the left atrium via the pulmonary vein and since the distance is short as compared with the systematic circulation, the pulmonary circulation operates at comparatively low pressure. This allows an efficient exchange of gases in the lungs, and also this low pressure would also not damage the delicate tissues of the lungs. (Encyclopaedia Britannica, 1991) (b) When the heart is detached from the body, it continues to beat because of the myogenic nature of the cardiac muscles. This means that it is able to generate electrical impulses without any external stimuli. That is it can continue beating rhythmically, without any nerve supply. This is because of the multiple pace maker cells, which are present in the heart muscle, which can continue to generate electrical impulses on their own. The key cell is called the sinus node. This is located on the upper side of the atria and is also called the Sino atrial node. This controls the rate at which the heart beats and thus controls the generation of the action potential. (Anon., 2008) When the heart is isolated from the body, it is deprived of essential nutrients and oxygen, and this leads to the occurrence of certain homeostatic changes. The tissues of the heart need a moist environment to survive, and if they are exposed to dry air for too long, the cells can dry out and hence, fall apart. To prevent this from occurring, the heart is kept in a special isotonic solution called the Ringer’s solution. This lactated solution consists of ions such as sodium and potassium, so that the heart can continue generated the action potential, and the cells don’t dry out. Anon., 2008. Signal transduction in the cardiovascular system in health and disease. s.l.:Springer. Chiras, D. D., 2011. Human Biology. s.l.:Jones & Bartlett Learning. Encyclopaedia Britannica, i., 1991. The New Encyclopaedia Britannica: Marcop?dia. s.l.:Encyclop?dia Britannica. Noble, A., 2005. The cardiovascular system. s.l.:Elsevier Churchill Livingstone. Toby Fagan, R. S., 2002. Cardiovascular system. s.l.:Elsevier Health Sciences. Question 5: Criteria Website 1- Teach Net Website 2- The Lung Association Ranking Comparison Anatomy information & Explanation of Structures Very few diagrams, only detailed diagram of the alveoli.(anatomy well-explained) Detailed diagram of the respiratory tract, but less detail about the internal structures. Anatomy not explained properly. Website 1=3 Website 2=2 Website 1 contains better info regarding anatomy of the alveoli with brief explanation; Website 2 does not contain detailed info regarding anatomy of the alveoli and other related structures. Definitions, and terms used Proper Medical terms used , good definitions Very general definitions and common terms used. Website 1- 3 Website 2-1 Website 1, contains better, more significant definitions, extra links are also provided; whereas website 2 contains general terms, mostly for the understanding of children. Additional links Many links to other websites provided, such as link 1, how lungs work. Internal links not working properly, and hardly any links to other websites. Website 1- 4 Website 2-1 Website 1 provides many additional links, which contain good information and more detail regarding the anatomy and functioning of the lungs. Whereas website 2, has insufficient information regarding the anatomy and has hardly any external links. Website layout and colors Neat and systematic layout. Really colorful website, with a lot of tabs. Website 1-3 Website 2-2 Question 6: (a) The first few days after Peter broke his leg, must have been extremely painful if he tried to walk or even move his left leg. This is because apart from the broken bone, the muscle tissue around the bone must have been damaged causing it to become inflamed and extremely painful. This is why the doctor must have advised him to not move his left leg at all, and give it as much rest a possible. Meanwhile, Peter must have been putting all his body weight on his right leg instead, causing strain on the right leg’s muscles and even some muscular pain. (Wistar, 1817) But with the passage of time, the muscles must have grown stronger and increased in mass, causing the size of the leg to become larger. Whereas the muscles of the left leg, become limp and flaccid, since they have been without exercise for seven weeks. The muscles attached to directly to the bones are called the skeletal muscles. Even though the leg has been in arresting position, the resting position must have caused a tension in the muscles called the muscle tone. A muscle which is in the state of rest has a smaller muscle tone, causing the muscle to be soft and limp. This helps hold the bones into place, along with additional cast, so that the fractured bone is repaired. (Gunn, 2002) The bone is repaired is in four stages. Firstly at the point of the fracture, there are a lot of capillaries and tissue cells which are broken, causing a clot to form. This clot is also known as a hematoma. The formation of this hematoma blocks the blood supply to the bone and the surrounding tissue, causing the cells to be deprived of nutrition. The cells become painful and swollen as a result. Then the immune system of the body takes over sending white blood cells to the area of the clot. The white blood cells secrete antibodies to digest any harmful bacteria that maybe present at the site. Then the fibroblastic cells and the osteoblast cells produce collagenous fibers which form a matrix and join the broken ends of the bone. At this stage a spongy sort of bone has been formed. This spongy bone is then hardened by a firm type of callus. This makes the bone stiffer, and this deposition continues until the bone matrix is rigid. The final and the comparatively longer stage is called bone remodeling. (b) The answers to Peter’s questions: ’Why does my repaired leg look as if it has shrunk’? This is because the muscles of the left leg have shrunk due to continued inactivity for the past seven weeks. The muscle tissue has become limp and soft, causing it to seem smaller and reduced in size. Whereas the right leg, has been prone to more stress and activity during these few weeks, causing it to become stronger and increase in size. ‘It is thin and weak especially when compared to the other leg…..will it ever go back to normal’? Since the leg has undergone severe internal trauma and has been without any exercise for the past few weeks, it is weak. But with time as u slowly begin to move your leg and put your weight on it, it should become stronger. It is recommended however, to regularly visit a physiotherapist, who could walk you through the initial stages, as it could be detrimental for the leg if you put a lot of strain on it all at once. ‘And should I be careful with it? I am worried that it might break again’? Yes, of course, you need to be extremely careful with it. Even though the cast has come off, this doesn’t mean that your leg is completely repaired. The healing process is still going on , and will take several months to complete. Trying to walk fast or even run at this stage, could be harmful and could interfere with the healing process. ‘Do you think I be able to play football again’? Yes, you will be. But not immediately. You need to let your leg mend completely before you start playing again, else it could get damaged again. It will probably take a few more months till you can play again. References: Gunn, C., 2002. Bones and joints: a guide for students. s.l.:Elsevier Health Sciences. Wistar, C., 1817. A system of anatomy for the use of students of medicine, Volume 2. s.l.:Thomas Dobson. Read More