Human health and disease by mohan bio

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Human health and disease by mohan bio

  1. 1. CHAPTER 8 : HUMAN HEALTH AND DISEASES
  2. 2. • Health: • Health is defined as a state of complete physical, mental and social well-being. • When people are healthy, they are more efficient at work. This increases productivity and brings economic prosperity. • Health also increases long life and reduces infant and maternal mortality. • The good health is maintained by balanced diet, personal hygiene and regular exercise.
  3. 3. • The health is affected by – 1. Genetic disorders . 2. Infections. 3. Life style including Diet, rest and exercise. Drug and alcohol abuse also affect our health adversely. • Diseases are grouped into infectious and noninfectious. • Diseases which are easily transmitted from one person to another are called infectious diseases. • Diseases which are not transmitted from one person to another are called non infectious diseases.. • Cancer is the non-infectious that cause death.
  4. 4. • COMMON DISEASES IN HUMANS: • organisms belonging to bacteria, viruses, fungi, protozoans, helminths, etc., cou ld cause diseases in man. Such disease causing organisms are called pathogens. • TYPHOID: • Pathogen: Salmonella typhi (bacterium) • Organs affected: small intestine, migrate to other organs through blood. • Method of transmission: contamination of food and water.
  5. 5. • Symptoms: • High fever (390 to 400 C) • Weakness, stomach pain, constipation, headache and loss of appetite. • Intestinal perforation may leads to death. • Test: Typhoid fever could be confirmed by Widal test.
  6. 6. • PNEUMONIA: • Pathogen: Streptococcus pneumoniae and Haemophilus influenzae. • Organs affected: Alveoli of lungs, alveoli get filled with fluid.
  7. 7. • Method of transmission: Inhaling the droplets/aerosols released by infected person. • Symptoms: • Fever, chills, cough and headache. • In severe cases the lips and finger nails turn gray to bluish colour.
  8. 8. • COMMON COLD: • Pathogen: Rhino viruses. • Organs affected: nose and respiratory passage • Method of transmission: • Direct inhalation of droplets from infected person. • Through contaminated objects like pen, books, cups, computer key board.
  9. 9. • Symptoms: • Nasal congestion and discharge, sore throat, hoarseness, cough. tiredness, etc., • It usually last for 3-7 days.
  10. 10. • MALARIA: • Pathogen: Plasmodium. (P. vivax, P. malariae, P. ovale, P. falciparum) • Malignant malaria caused by P. falciparum is fatal. • Organs affected: liver, RBC. • Method of transmission: By biting of female anopheles mosquito (vector)
  11. 11. • Symptoms: high fever and chill, fever occurs on every alternate day, vomiting.
  12. 12. • life cycle of malaria parasite: • The malarial parasite requires two hosts – human and Anopheles, to complete their life cycle. • Life cycle of plasmodium starts with injecting sporozoites through the bite of infected female Anopheles mosquitoes. • The parasite initially multiplied within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture.
  13. 13. • There is release of a toxic substance called hemozoin from the ruptured RBCs. It is responsible for the chill and high fever. • From the infected human the parasite enters into the body of Anopheles mosquito during biting and sucking blood. • Further development takes place in the body of Anopheles mosquitoes.
  14. 14. • The female mosquito takes up gametocytes with the blood meal. • Formation of gametes and fertilization takes place in the intestine of mosquito. • The zygote develops further and forms thousands of sporozoites. • These sporozoites migrated into the salivary gland of mosquito. • When the mosquito bite another human sporozoites are injected.
  15. 15. • AMOEBIASIS (Amoebic dysentery) • Pathogen: Entamoeba histolytica a protozoan parasite. • Organs affected: large intestine of man • Method of transmission: • House fly acts as mechanical carrier. • Contamination water and food with faecal matter. • Symptoms: • Loose motion and abdominal pain. • Stools with excess mucous and blood clots.
  16. 16. • ASCARIASIS: • Pathogen: Ascaris lumbricoids (nematode) • Organs affected: intestine of man • Method of transmission: Contaminated water, vegetables, fruits. • Symptoms: • Internal bleeding, muscular pain, fever, anemia. • Blockage of the intestinal passage.
  17. 17. • FILARIASIS OR ELEPHANTIASIS: • Pathogen: Wuchereria (W.bancrofti and W. Malayi) (nematode parasite) • Organs affected: lymphatic vessels of the lower limbs, genital organs. • Methods of transmission: biting of infected female culex mosquito. • Symptoms: • Chronic inflammation of the organs. • Abnormal swelling of lower limb, scrotum, penis. • Hence the disease named as elephantiasis or Filariasis.
  18. 18. • RING WORMS: • Pathogen: Microsporum, Trichophyton and Epidermophyton (fungi) • Organs affected: Skin, nails, folds of skin, groin. • Method of transmission: • Acquired from the soil. • Using towel, clothes or even comb of infected individuals. • Symptoms: • Appearance of dry, scaly lesions in skin nails and scalp. • Lesion accompanied with intense itching.
  19. 19. • PREVENTION AND CONTROL OF INFECTIOUS DISEASES: • Maintenance of personal and public hygiene. • Personal hygiene includes Consumption of clean drinking water, food vegetable fruits. Keeping the body clean. • Public hygiene includes Proper disposal of waste and excreta • Periodic cleaning water reservoirs, pools. • Avoiding close contact with the infected persons. • For vector borne diseases controlling vectors and the breeding places. • Avoiding stagnation of water in and around residential areas. • Use of mosquito nets. • Window and doors must be fitted with wire mesh. • All these precautions are use full for vector borne disease like dengue and Chickungunya, malaria and filarial etc.
  20. 20. Immunity: Immunity is the ability of an organism to resist infection or to overcome infection. • There are two types of immunity: 1. Innate (non-specific) Immunity. 2. Acquired (specific) Immunity. • Innate or Non-specific Immunity: It is the inborn or natural immunity. It is of two types, 1. Surface barrier. 2. Cellular and Biochemical barrier. • Surface barrier: It is the first line body defense. It includes the external barriers that checks the entry of pathogens into body. • It is identified as physical barrier and Physiological (chemical) barrier.
  21. 21. Physical barrier: The important physical barrier are skin, hair and cilia of nasal cavity, mucous lining and muscular action. Skin: • The skin prevents entry of pathogens. • The sweat produced by sweat gland and oil produced by sebaceous gland are bactericidal and fungicidal properties.
  22. 22. • Mucus lining: The mucus lining found in respiratory tract, digestive tract, urinary tract and reproductive tract secretes mucus. The mucus traps the microbes and makes them immobilize. Physiological barriers: Chemical secretion like lysozymes, skin secretion, saliva and ear wax forms physiological barriers. Lysozyme: • It is an antibacterial enzyme present in tears, nasal secretion, saliva, and most of the body fluids. It lyses the bacterial cell. Skin secretion : • The sweat and sebum has antibacterial and antifungal properties. It avoids the growth of bacteria and fungus on skin.
  23. 23. Saliva: • The saliva contains lysozyme that lyses the bacteria. • Gut secretion: • The gastric juice contains dil HCl. It kills the microbes enters through food. • Ear wax : • The ear wax secreted in external auditory canal is bactericidal in nature. It repels the insects. It traps the dust.
  24. 24. Cellular and biochemical barrier: It is the second line body defense. It includes 1. Phagocytes 2. Natural killer cells (NK cells) 3. Interferons. 4. Inflammatory response. • Phagocytes: The process of engulfing and destroying the microbe by some cells is called phagocytosis. • The cells that involves in phagocytosis are called phagocytes. • The neutrophils and monocytes (macrophages) types of WBC are the important phagocytic cells.
  25. 25. Process of phagocytosis
  26. 26. • Natural killer cells (NK Cells): • Natural killer cells are non-phagocytic large lymphocytes. • It mainly recognizes the viral infected cells and tumor cells. • It destroys them by secreting cytolysin. Hence these are called killer cells.
  27. 27. • Interferon: • Interferon are the antiviral glycoprotein produced by viral infected animal cell. It protects the neighboring cells from viral infection. • It mainly stimulates neighboring cells to synthesis a protein that interfere with viral replication. It also activates macrophages and NK cells to recognize infected cells.
  28. 28. Interferon:
  29. 29. • Inflammatory response: It is the localized response to injury, infection or irritation. The symptoms are getting redness, swelling, pain, increasing body temp etc. • Acquired (specific) immunity: • It is the defense mechanism acquired by healthy person against specific pathogens and infection. It forms the third line body defense. • Lymphocytes are the important components activating specific body defense. • The two types of lymphocytes are T- lymphocyte and B – lymphocyte.
  30. 30. • T – lymphocytes • The undifferentiated lymphocytes originate from the stem cells of bone marrow, • Some of them migrate to thymus gland and differentiated into Tlymphocyte. .
  31. 31. • B– lymphocytes: • The undifferentiated lymphocytes originate from the stem cells of bone marrow. • some migrate to Bursa equivalent and differentiated into B-lymphocyte. • Bursa equivalent is a hypothesized lymphoid tissue in bone marrow. • (Bursa equivalent is found in mammals, Bursa fabricius is found in birds.)
  32. 32. • Antigen: Any foreign substance that enters our body and stimulates immune response is called antigen. Antigen has two properties: • Antigenicity: It is the ability of an antigen to generate specific immune response to produce antibody. • Immunogenicity. • It is the ability of an antigen to react with specific antibody. • Biochemically antigens are proteins, large polysaccharides, lipids, fatty acids or nucleic acids. Sometimes entire pathogen acts as antigen.
  33. 33. Antibody or immunoglobin (Ig) • The protein molecule that produced by Blymphocytes against a specific antigen is called antibody. • These are mainly classified in to 5 types. They are, IgM, IgA, IgD,IgE, IgG. ( MADE-G) • IgM is a pentamer and is a mega globulin. It is the first reaches the injured site. • IgA is the secretory antibody. • IgD it binds to B - Lymphocytes and acts as a surface receptor. • IgE play imp role in allergy. • IgG crosses placenta and protects foetus.
  34. 34. Structure of Antibody. • Antibody is mainly known as immunoglobulin. It is a Y shaped made up of four polypeptide chains. • Among four chains two are longer chains called heavy chains. • Two are smaller called light chain. • The four polypeptide chains are held together by di-sulphide bond.
  35. 35. • Each chain contains constant and variable region. • In constant region the amino acid sequence are constant and same in all antibodies. • In variable region the amino acid sequence varies with different antibodies. • The variable region is present at the tip of Y arm forms antigen binding site.
  36. 36. Role of B – lymphocytes: • The lymphocytes produced at bone marrow differentiates in bursa equivalent in to B – lymphocyte. • When the antigen enters in to the body number of B – lymphocytes stimulated to produce antibody. • Once the antigen specific antibody producing B – lymphocyte activated, it multiplies rapidly to produce number of cloned cells. • The cloned B – lymphocytes differentiates in to plasma cells. These cells produces specific antibody against antigen in large quantity. • The cloned B – lymphocyte that undifferentiated remains as memory B cells. When the same antigen enters again in future, memory cells response rapidly to destroy them.
  37. 37. Cell mediated immunity ( CMI ): It is the immunity mediated by T – lymphocytes. Role of T – lymphocytes: • The lymphocytes produced at bone marrow differentiates in thymus in to T – lymphocyte. It does not produce any antibody. It directly acts on antigen. • When the antigen enters in to the body, the antigen specific T – lymphocyte stimulated and becomes active. • The activated T – lymphocyte multiplies rapidly to produce number of cloned cells.
  38. 38. According to function of T – lymphocyte, these are identified in to , • Killer T-cells: These T - cells recognizes specific pathogen and destroys by lyses. • Helper T – cells: These T – cells helps in stimulating antigen specific B – cells to produce antibody. • Suppressor T – cells: These T – cells suppress the immune response of both B and T cells, when infection is controlled. • Memory T – cells: These T – cells are programmed to recognize and response to the specific antigen that enters in future.

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