Disease and Man Form 5 Biology PDF

Class: Form 5 Biology Topic: Disease and Man Objectives: 1. Define disease. 2. Distinguish between pathogenic, deficiency, hereditary and physiological disease. 3. Discuss methods of treatment and control of the 4 main types of disease. 4. Identify the stages in the life cycle of the mos...

Class: Form 5 Biology Topic: Disease and Man Objectives: 1. Define disease. 2. Distinguish between pathogenic, deficiency, hereditary and physiological disease. 3. Discuss methods of treatment and control of the 4 main types of disease. 4. Identify the stages in the life cycle of the mosquito. 5. Discuss the role of the mosquito as a vector in the transmission of disease. 6. Suggest appropriate methods of control of each stage of the life cycle of the mosquito. 7. Identify the social and economic implications of disease in plants and animals. Objective 1: Define disease. A disease is a condition that impairs the normal functioning of cells, tissues or organs which leads to impairment in the health of the whole organism. Objective 2: Distinguish between pathogenic, deficiency, hereditary and physiological disease. Objective 3: Discuss methods of treatment and control of the 4 main types of disease. There are 4 main categories of disease: 1. Pathogenic 2. Deficiency 3. Hereditary 4. Physiological Pathogenic Disease Disease caused by invading organisms like viruses, fungi, bacteria, protozoa and worms is classified as being pathogenic. A pathogenic organism lives on or inside an organism called the host. Examples include: - Virus : influenza - Fungi : Athlete’s foot (tenia pedis) - Bacteria : syphilis (treponema pallidum) - Protozoa : amebiasis (amoeba) - Worms : tape worm infection Pathogenic diseases, in general, are treated by trying to kill the invading organism and treating the symptoms of the disease. Control involves limited exposure to circumstances that may increase one’s risk of infection. COVID-19 is an example of a pathogenic disease as it is caused by a virus. Treatment at this time consists of administering monoclonal antibodies which kill the virus as well as supportive care. What are some of the things that can be done to control the spread? - Social distancing - Mask wearing - Hand washing - Hand sanitizing - Staying out of crowded areas Deficiency Disease A disease caused by the deficiency of a nutrient, vitamin or mineral in a diet is classified as being a deficiency disease. Some common deficiency diseases include: - Vitamin C deficiency: scurvy - Iron deficiency : anemia - Protein deficiency : kwashiorkor Control of deficiency diseases involves education about maintaining a balanced diet and actually maintaining a balanced diet. Treatment of deficiency diseases involves administering or consuming the deficient nutrient, vitamin or mineral. Hereditary Disease Disease caused by genes passed from one generation to the next is classified as being a hereditary disease. Some common hereditary diseases are: - Sickle cell anemia - Hemophilia - Cystic fibrosis The only method for trying to control hereditary diseases is through genetic counseling. Genetic counseling is the process through which knowledge about the genetic aspects of illnesses is shared by trained professionals with those who are at an increased risk or either having a heritable disorder or of passing it on to their unborn offspring. Most hereditary diseases are treated by treating the symptoms of the disease with the majority of hereditary diseases having no cure however, advances in stem cell research and genetic engineering have shown promise in the treatment of hereditary diseases. Physiological Disease Disease caused by the malfunction of an organ in the body is classified as being physiological. Some examples of common physiological diseases are: - Asthma - Glaucoma - Heart attack - Diabetes (Type 2) - Hypertension These diseases are very often heavily influenced by human behaviour e.g. diet and exercise and so control targets these areas. Treatment often involves altering the behaviour that caused/causes the problem and can include medication. Objective 4: Identify the stages in the life cycle of the mosquito. Eggs are laid in a single file onto the surface of the water. Larvae emerge from eggs and hang down from the surface of the water and breathe through air tubes. They feed on microorganisms present in the water. They swim by twitching. The larvae molts 4 times to form the comma-shaped pupa. This is the non-feeding stage. They too,hang from the surface of the water and breathe through airtubes. The pupa splits along the back and the adult climbs out onto the surface of the water and flies away. Objective 5: Discuss the role of the mosquito as a vector in the transmission of disease. A vector is an organism that carries disease-causing pathogen from host to host. Vectors spread pathogenic diseases. The mosquito is an example of a disease vector. They spread yellow fever, malaria, dengue, zika and chikungunya in their saliva. Objective 6: Suggest appropriate methods of control of each stage of the life cycle of the mosquito. If the vector can be controlled then the disease it spreads can be controlled as well. Some methods of control of mosquitoes include: - Draining stagnant water (prevents mosquitoes from laying eggs) - Spreading a thin layer of oil over the surface of water (keeps the larvae and pupa from breathing so suffocates them) - Insecticides (kill the adult) - Mosquito nets (prevent adult from biting) - Clearing bush around home where adult mosquitoes rest. - BHC (benzene hexachloride) fog effective for up to 30 days and targets all life stages. - Fish that feed on the larval and pupal stages can be introduced into the water if possible. - Biological control: adding bacteria Bascillus thuringiensis to the water. Larvae eat the bacteria and bacteria multiply in their gut causing the gut to burst and killing the larvae. Objective 7: Identify the social and economic implications of disease in plants and animals. - The grief and fallout caused from loss of life due to disease is an important social factor. - The loss of skilled workers and working hours which impact productivity is an important economic factor. - Cost of treatment of disease. - Loss of livestock and agricultural crops can have detrimental economic consequences.