Life Science, Cells - Assignment Example

1. Explain why water is such an important compound in biology, with reference to its various properties. Explain, using a diagram if you wish, how a salt or other ionic compound may dissolve in water. Ans. Water is critical for sustaining life. Water functions as a reactant in metabolic reactions, as a solvent for organic and inorganic substances, as a transportation medium for dissolving chemicals and as a support mechanism for plants and organisms (Biology 2011). When dissolving salt in water, the positive poles of some water molecules will attract the negatively charged salt ions and the negative poles of other water molecules will attract the positively charged salt ions. The ionic bonds break and the water molecules enclose the free ions (Intro Solution: the Role of Charge 2011). 2. Describe the different phases in cell division, for both somatic and reproductive cells. Ans. Mitosis (somatic cells) occurs in four phases: prophase, metaphase, anaphase and telophase. In prophase, the chromosomes coil and condense into a spindle. Centrioles travel to opposite poles of the spindle; the nuclear membrane separates. In metaphase, the sister chromatids (with its respective centromere) stand at opposites in the spindle’s center. In anaphase, each chromatid becomes a new chromosome. The chromosomes uncoil, forming new nuclear membranes in telophase. Meiosis (reproductive cells) occurs in reduction division (where the sex cells first divide) and equal division(mitosis)(Beta-Theta.Com 2011). 3. Describe and give example of how both benign and malignant tumours may cause harm in the body. Ans. Benign tumours grow slowly but cause harm in the body if they become large, causing local pressure symptoms. For example, tumours born from the cells in hormone glands can cause excess hormone levels leading to unwanted effects. Malignant tumours are cancerous and cause definite harm in the body. These tumours grow quickly, attacking nearby tissues and organs; this causes secondary tumours that spread in the same manner. For example, cancerous blood cells (leukaemia) are formed in the bone marrow and then travel through the bloodstream (Cancersocietygh.com 2008). 4. Describe the resting membrane potential in neurons. Explain how electrical signals are generated and explain the difference between a graded and action potential. Ans. Electrical signals are generated when ion channels open or close in the cell membrane. The membrane potential of a cell that exists for an extended time frame without changing considerably is called the resting membrane potential in neurons. A graded potential is when the membrane potential changes in a neuron. Graded potentials occur in non-excitable cells and in excitable cells (only when there is no excitation). An action potential is when the membrane potential changes quickly in excitable cells, the charge reversing momentarily (Medscape (2) 2011). 5. Explain how blood calcium homeostasis is maintained by parathyroid hormone, calcitonin and calcitriol. Ans. Parathyroid hormone (PTH) is the most important regulatory hormone; PTH decreases when serum calcium concentrations increases. During normal loss (urine, stool) of calcium and when the body absorbs less calcium (in aging), the PTH increases its secretion. Administering sufficient calcium prevents this calcium loss and PTH synthesis. Calcitonin (released by the thyroid gland) will reduce the amount of calcium in the blood by increasing the amount of calcium in the bone. Calcitriol is a form of vitamin D that encourages calcium absorption in the body (Health-Diets.Net 2011). 6. With reference to the actions of cortisol in the body, explain why prolonged stress may increase the risk of cardio-vascular disease and type 2 diabetes. Ans. Cortisol is an essential hormone in the body and is involved in blood pressure regulation and insulin release. Cortisol is released to the body’s ‘fight or flight’ reaction to stress. Stress causes a high level of cortisol release in the body. It is important for the body to relax and return to normal mode. When the body fails to relax after a stressful event, high and continued levels of cortisol result in increased abdominal fat (risk of cardio-vascular disease) and insulin resistance (type 2 diabetes)(Scott 2008, 2010). 7. Explain what happens to haemoglobin when a red blood cell is broken down. Ans. Haemoglobin is taken out of the red blood cell and used to produce more iron. After a red blood cell breaks down, haemoglobin usually leaks into the blood and breaks down into globins and heme groups. The heme groups open up and the iron atom seeps out, rapidly attaching itself to a plasma protein (transferrin). Transferrin takes the iron through the blood for further haemoglobin production or for storage in the liver. Thus, the iron atom is reused to produce more haemoglobin in the body. (Tamarkin 2011). 8. Discuss the factors that contribute to development of DVT on long haul flights. Suggest ways to decrease the risk. Ans. Long haul flights involve extensive sitting. This immobility causes blood to stagnate in the legs. Typically, blood in the veins form microscopic clots that the body routinely breaks down. When this routine changes, a blood clot (thrombus) forms in the leg’s deep venous system, this is called deep vein thrombosis (DVT). The thrombus becomes dangerous if it travels and lodges in the lung. Frequent muscle movement, such as walking and stretching, decreases the risk of DVT. Diagnosis and treatment of DVT can prevent pulmonary embolism (Wedro 2011). 9. Compare and contrast antibody and cell mediated immunity. Ans. Antibody mediated immunity (also called the humoral immune response) occurs when secreted antibodies are produced in B cells. These antibodies will attach to the antigens on the viral or bacterial surface and highlights them for destruction, leading to the riddance of the pathogen. Cell mediated immunity is an immune response to an antigen not involving antibodies (as in antibody mediated immunity). Instead, macrophages, natural killer cells and T-lymphocytes will be activated with the onset of various cytokine release (Medscape 2011). 10. Describe the steps in a type I hypersensitivity reaction. What is the purpose behind the body reacting this way? Ans. Allergic reactions occur when the body’s immune system reacts wrongly to a foreign antigen (allergen) that is otherwise non-threatening; this is the body’s initial response to the allergen. Type I hypersensitivity (anaphylactic reactions) is the body’s second response to the allergen, a reaction that is susceptible in those who have a hereditary trait towards these reactions. The body produces antibodies and histamines against the antigen, causing mucous secretion. In severe cases, breathing becomes difficult, blood pressure lowers and death results (The Microbial World 2006). 11. Describe the various ways bacteria and viruses cause disease in the body. Ans. Bacteria and viruses cause disease when viral and bacterial infections spread in the body through coughing/sneezing, touching an infected person, touching food with soiled hands and transmission of infected body fluids. Viruses are unable to reproduce alone, taking over a cell in order to replicate. However, bacteria are able to multiply on their own and already exist inside and outside our bodies. Bacteria cause diseases when they are meant to attack us or secure a place in the body where it should not inhabit (Worden 2010). 12. Explain what is meant by the oxygen-haemoglobin dissociation curve, and what it means if this curve moves to the left or right. List and briefly explain factors that decrease the affinity of haemoglobin for oxygen and whether they are physiologically beneficial. Ans. Oxygen-haemoglobin dissociation curves represent the blood’s oxygen content at oxygen’s different partial pressures. Increases in hydrogen ions, carbon dioxide, or 2,3-DPG decreases the affinity of haemoglobin for oxygen, shifting the curve to the right (decreases in hydrogen ions, etc. shifts the curve to the left). This is physiologically beneficial in high altitude environments where oxygen accessibility is reduced. Increases in body temperature decrease the affinity of haemoglobin for oxygen; this isn’t physiologically beneficial because the body experiences minimal temperature change (Encyclopaedia Britannica 1995). 13. Describe how the existence of chronic bronchitis may be a ‘vicious circle’ leading to further lung damage. Ans. In chronic bronchitis, due to a constant irritant (such as cigarette smoking), fluids permanently swell the lungs’ airways and reduce airflow to smaller, surrounding air passages. Lungs increase their production of mucuous but because the airways are blocked, coughing loses its force to eliminate the mucuous. The mucuous remains captive in this moist environment where bacteria begin breeding. Mucuous production increases to eliminate the irritant while bacteria continue growing and spreading, hence the ‘vicious circle’. This ‘vicious circle’ furthers lung damage by eventually causing emphysema (COPD 2011). 14. Based on the roles of the stomach, small intestine and large intestine, removal of which organ would carry the worst prognosis and why? Ans. Removal of the small intestine carries the worst prognosis because it forms 75% of the digestive tract and 90% of the surface of the digestive tract. The small intestine connects the stomach to the large intestine. The body absorbs crucial minerals, nutrients and vitamins after the small intestine does its role in breaking down and absorbing food (Vapiwala 2011). Incidentally, the small intestine can assume the functions of the stomach or large intestine. Surgery of the small intestine creates a surrogate stomach or surrogate large intestine (Newitz 2008). 15. Explain what is meant by the term ‘metabolism’. Explain why having a fast metabolism generally leads to weight loss and a slow metabolism to weight gain. Ans. Metabolism is the total energy (calories) the body burns to control its important functions. Every action of the body requires the burning of calories. Muscle, unlike fat, burns more calories for maintenance. The more muscle an individual has means a faster metabolism. The less muscle an individual has means a slower metabolism. Thus, a person who exercises builds more muscle tissue and is able to lose weight compared to a person who does not exercise (and has less muscle tissue) and instead gains weight (Moore 2011). 16. Outline the key differences between type 1 and type 2 diabetes. Ans. Type 1 and type 2 are two main types of diabetes. Type 1 is an inherited, autoimmune disease where the immune system attacks the cells of the pancreas (accountable for insulin production). Due to this attack, the pancreas is unable to make insulin and a lifetime of insulin medication is needed. Type 2 diabetes results later in life due to obesity, compromised eating habits, and no exercise. Here, the pancreas produces either more than necessary amounts of insulin or produces it in very low amounts (MedicineNet.com 2011). 17. From a natural therapies perspective, suggest some simple strategies for decreasing the main diseases affecting the indigenous Australian population. Ans. The main diseases affecting the indigenous Australian population include cardiovascular disease, high blood pressure, STDs and diabetes (Better Health Channel 2010). From a natural therapies perspective, simple strategies can decrease this trend: by educating local service providers on mental health, drug and health problems, they can educate the indigenous Australian people. Health checks on children are also needed to detect and prevent child sexual abuse. Doctors and nurses are needed to provide primary health care; they can work together with local organizations for current solutions and future preventions (Berry 2007). 18. With reference to the carbonic acid-bicarbonate buffer system, explain how the urinary and respiratory systems work together to regulate pH in the body. Refer to the terms respiratory acidosis with metabolic compensation and metabolic acidosis with respiratory compensation as examples in your answer. Ans. In the carbonic acid-bicarbonate buffer system, the respiratory system (via lungs) controls carbon dioxide amounts and the urinary system (via kidneys) controls bicarbonate amounts. Both systems regulate the body’s pH. Failure to remove carbon dioxide from the blood results in acidosis; acidosis occurs when the pH < 7.35. Different lung malfunctions generate respiratory acidosis; the kidneys compensate by increasing the pH (metabolic compensation). Extreme accumulation or depletion of acids or bases generates metabolic acidosis; the lungs compensate by hyperventilating to increase the pH (respiratory compensation) (Vchembook 2011, 2011). 19. If a male has a vasectomy, will they still ejaculate when they have an orgasm? Explain how this method of birth control works. Ans. A vasectomy is an efficient method of male birth control. Post surgery, birth control must be used because the remaining sperm must be ejaculated (typically takes 15 to 20 times) from both vas deferens before the testicles begin producing less sperm. This is because only a tiny portion of the vas deferens (still contains previous sperm) is removed. After the remaining sperm ejaculates, the body will absorb any sperm it produces thereafter. The body will continue ejaculating equal amounts of semen during an orgasm. (FamilyDoctor.org 2010). 20. Explain how it is that a mother with blood group A and father with blood group B can have a child with blood group O. Ans. Human blood cell membranes hold different antigens. A child receives one antigen from the mother and one antigen from the father. Antigens A, B and O are the most important of which A and B are termed the ‘dominant’ ones. An A-type antigen or a B-type antigen actually disguises the O-type antigen. So, a mother with blood group A and father with blood group B can produce a child with blood group O (blood groups A, B or AB are also possible) (NetDoctor Medical Team 2006). References Berry, Katherine 2007, Indigenous Health-Crisis, Natural Therapy Pages Forums, viewed 11 May 2011, < http://www.naturaltherapypages.com.au/forum/archive/index.php/t-98.html>. Beta-Theta.Com, Biology Section, viewed 10 May 2011, . Better Health Channel 2010, Aboriginal health issues, viewed 12 May 2011, . Biology 2011, The Importance of Water, viewed 11 May 2011, . Cancersocietygh.com 2008, What are Cancer and Tumours? , viewed 10 May 2011, . COPD 2011, Chronic Bronchitis, viewed 11 May 2011, . Encyclopaedia Britannica 1995, Respiration and Respiratory Systems, viewed 11 May 2011, . FamilyDoctor.org 2010, Health information for the whole family, Vasectomy: What to Expect, viewed 10 May 2011, . Health-Diets.Net 2011, Health and Nutrition Database, Adapted from the Nutritional Health Bible by Linda Lazarides, viewed 11 May 2011, < http://www.health-diets.net/healthsearch/cabbage.htm>. Intro Solution: the Role of Charge 2011, Dissolving ionic compounds such as sodium chloride, viewed 11 May 2011, . MedicineNet.com, Diabetes Mellitus (cont.), What are the different types of diabetes? viewed 10 May 2011,< http://www.medicinenet.com/diabetes_mellitus/page3.htm>. Moore, Linda 2011, What is a Metabolism? , viewed 11 May 2011, < http://www.slimmingresources.com/what-is-a-metabolism>. NetDoctor Medical Team 2006, Blood Type Comparison - parents and child Paternity Determination by Blood Type, viewed 10 May 2011, . Newitz, Annalee 2008. ‘How Many of Your Internal Organs Can You Live Without?’, viewed 11 May 2011, . Scott, Elizabeth 2010, Chronic Job Stress is a Risk Factor for Heart Disease, About.com Guide, viewed 10 May 2011, < http://stress.about.com/od/stresshealth/a/jobstress.htm>. Scott, Elizabeth 2008, ‘Cortisol and Stress: How to Stay Healthy’, About.com Guide, viewed 10 May 2011, < http://stress.about.com/od/stresshealth/a/cortisol.htm>. Tamarkin, A. Dawn 2011, ‘Hemoglobin is a protein’, STCC Foundation Press, viewed 10 May 2011, . The Microbial World 2006, The immune system is not perfect-Allergies, viewed 11 May 2011, . Vapiwala, Neha MD 2011, Cancer Types, Cancer of the Small Bowel, viewed 12 May 2011, < http://www.oncolink.org/types/article.cfm?c=5&s=74&ss=778&id=9498&CFID=14458672&CFTOKEN=41480243>. Vchembook 2011, Metabolic Acidosis, viewed 10 May 2011, . Vchembook 2011, Respiratory Acidosis, viewed 10 May 2011, . Wedro, Benjamin C. MD 2011, MedicineNet, Inc, Deep Vein Thrombus, How Pie Prevents Blood Clots, viewed 11 May 2011, . Medscape 2011, Humoral immunity, viewed 11 May 2011, . Medscape (2) 2011, Membrane Potential, viewed 11 May 2011, < http://medscape.coml>. Worden, Dr. Jeni 2010, Viruses and bacteria, viewed 11 May 2011, . Read More

5. Explain how blood calcium homeostasis is maintained by parathyroid hormone, calcitonin and calcitriol. Ans. Parathyroid hormone (PTH) is the most important regulatory hormone; PTH decreases when serum calcium concentrations increases. During normal loss (urine, stool) of calcium and when the body absorbs less calcium (in aging), the PTH increases its secretion. Administering sufficient calcium prevents this calcium loss and PTH synthesis. Calcitonin (released by the thyroid gland) will reduce the amount of calcium in the blood by increasing the amount of calcium in the bone.

Calcitriol is a form of vitamin D that encourages calcium absorption in the body (Health-Diets.Net 2011). 6. With reference to the actions of cortisol in the body, explain why prolonged stress may increase the risk of cardio-vascular disease and type 2 diabetes. Ans. Cortisol is an essential hormone in the body and is involved in blood pressure regulation and insulin release. Cortisol is released to the body’s ‘fight or flight’ reaction to stress. Stress causes a high level of cortisol release in the body.

It is important for the body to relax and return to normal mode. When the body fails to relax after a stressful event, high and continued levels of cortisol result in increased abdominal fat (risk of cardio-vascular disease) and insulin resistance (type 2 diabetes)(Scott 2008, 2010). 7. Explain what happens to haemoglobin when a red blood cell is broken down. Ans. Haemoglobin is taken out of the red blood cell and used to produce more iron. After a red blood cell breaks down, haemoglobin usually leaks into the blood and breaks down into globins and heme groups.

The heme groups open up and the iron atom seeps out, rapidly attaching itself to a plasma protein (transferrin). Transferrin takes the iron through the blood for further haemoglobin production or for storage in the liver. Thus, the iron atom is reused to produce more haemoglobin in the body. (Tamarkin 2011). 8. Discuss the factors that contribute to development of DVT on long haul flights. Suggest ways to decrease the risk. Ans. Long haul flights involve extensive sitting. This immobility causes blood to stagnate in the legs.

Typically, blood in the veins form microscopic clots that the body routinely breaks down. When this routine changes, a blood clot (thrombus) forms in the leg’s deep venous system, this is called deep vein thrombosis (DVT). The thrombus becomes dangerous if it travels and lodges in the lung. Frequent muscle movement, such as walking and stretching, decreases the risk of DVT. Diagnosis and treatment of DVT can prevent pulmonary embolism (Wedro 2011). 9. Compare and contrast antibody and cell mediated immunity. Ans. Antibody mediated immunity (also called the humoral immune response) occurs when secreted antibodies are produced in B cells.

These antibodies will attach to the antigens on the viral or bacterial surface and highlights them for destruction, leading to the riddance of the pathogen. Cell mediated immunity is an immune response to an antigen not involving antibodies (as in antibody mediated immunity). Instead, macrophages, natural killer cells and T-lymphocytes will be activated with the onset of various cytokine release (Medscape 2011). 10. Describe the steps in a type I hypersensitivity reaction. What is the purpose behind the body reacting this way? Ans. Allergic reactions occur when the body’s immune system reacts wrongly to a foreign antigen (allergen) that is otherwise non-threatening; this is the body’s initial response to the allergen.

Type I hypersensitivity (anaphylactic reactions) is the body’s second response to the allergen, a reaction that is susceptible in those who have a hereditary trait towards these reactions. The body produces antibodies and histamines against the antigen, causing mucous secretion. In severe cases, breathing becomes difficult, blood pressure lowers and death results (The Microbial World 2006). 11.

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