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Saturday, 15 December 2018

December 15, 2018

Some Important Microbial Human Beings





Pathogens - Disease - Method of spread - Notes


VIRUSES

• Poxvirus - Smallpox - Air bone - Serious disease now eradicated

• Paramyxovirus - Measles - Air bone and close contact - Child hood disease,; measles vaccine gives protection

• Paramyxovirus - Mumps - Air bone and close contact - Childhood disease

• Herpesvirus  - Chickenpox - Air bone and close contact - Child hood disease

• Picornavirus- Poliomyelitis (infantile paralysis) - Through food and water contaminated with faeces; droplets; and direct contact - No specific treatment; major outbreak sweeps the world every 11 years

• Variety of viruses - Common cold - Air bone - No specific treatment

• Arbovirus - Yellow fever - Bite of infected Aedes mosquito (biological method) - Serious disease; vaccine gives protection

• Rhabdovirus  - Hepatitis A (Infective hepatitis) - Through contaminated food , water and palm wine - Common cause of jaundice

• A DNA virus - Hepatitis B (Serum hepatitis) - Through infected blood and blood products given via transfusions and injections - Carriers help to spread the disease

• Retrovirus (human immunodeficiency virus or HIV) - Acquired immune deficiency syndrome or AIDS (infected people may not shoe signs of the disease for years, but can spread it to others) - Through sexual contact; blood transfusion; infected needles and injection syringes; and infected mother to unborn child - Virus attacks and destroys body defense (immune) system, making the person susceptible to all microbial infections and some cancers; eventual death

BACTERIA

• Vibrio cholerae - Cholera - Through food and water contaminated with faeces; flies and carriers important in causing God contamination - Vomiting and diarrhea cause dehydration of body leading to death unless fluid is given through the blood vessels

• Salmonella typhi - Typhoid - Same as for cholera - High fever followed lager by bloody diarrhoea due to intestinal ulcers; treated with antibiotics

• Shigella dysenteriae  - Bacteria dysentery - Same as for cholera - Abdominal pain and diarrhoea

• Salmonella sp. - Food poisoning - Mainly through infected meat, poultry, eggs and milk; also via food contaminated by faeces - Diarrhoea and vomiting usually subside in 2 to 4 days

• Clostridium tetani - Tetanus or lockjaw - Through soil, dust or faeces - Spines germinate and multiply rapidly in oxygen starved environment found in cuts and wounds

• Corynebacterium diphtheriae  - diphtheria - Air bone - Toxin causes tissue damage; vaccine gives protection

• Mycobacterium tuberculosis - Tuberculosis - Air bone ; drinking milk from infected cattle - Serious childhood disease; vaccine gives protection

• Bordetella pertussis - Whooping cough - Airborne - serious childhood disease vaccine gives protection

• Neissera gonorrhoeae - Gonorrhoea - Direct contact through sexual intercourse - Venereal disease

• Treponema pallidum - Syphillis - Same as for gonorrhea - Serious venereal disease; long incubation period

• Treponema pertenue - Yaws  - Direct skin contact , and through files - Common in children now eradicated

PROTOZOA

• Entamoeba histolytica - Amoebic dysentery - Through food and water contaminated with faeces containing amoebic cysts; flies act as carries between faeces and food - Diarrhoea and abdominal pains

• Trypanosoma gambiense - Sleeping sickness - Through bite of infected tsetse fly - Serious disease found only in tropical Africa; affects nervous system

• Plasmodium sp. - Malaria - Bote of infected anopheles mosquito - Diseases characterized by bouts of chills, fever and sweating

FUNGI

• Dermatophytes: filamentous fungi that grow on skin hair and nails  - (I) Tinea versicolor - Direct skin contact - A common type of body ringworm with yellow patches in chest, neck, face and back

(ii) Onu madu  - Direct skin contact - Characteristic rash mainly on groins and folds of buttocks

(iii) Athlete's foot - Direct skin contact - Itchy , smelly patches between toes
December 15, 2018

Summary of the Main Organ Systems Found in the Human Body






Name of System - Main  organs in the system  - Main function

• Digestive system - Gut, liver and pancreas - To digest and absorb food

• Respiratory system - Windpipe and lungs - To take in oxygen and get rid of carbon dioxide

• Circulatory System - Heart , blood vessels - To carry oxygen and food round the body

• Excretory system - Kidneys, bladder, liver - To get rid of  poisonous waste substances

• Sensory system - Ears , eyes, nose , skin - To detect stimuli 

• Nervous system - Brain and spinal cord - To conduct messages from one part of the body to another

• Musculo skeletal system - Muscles and skeleton - To support and move the body

• Reproductive system - Testes and ovaries - To produce offspring
December 15, 2018

Movement in Insects





How muscles move exoskeleton in insects

In insects, muscles attached to the inner surfaces of the exoskeleton bring about movement of the legs, wings and other appendages.

Moving the legs: The exoskeleton in each leg consists of several tube like segments joined end to end. The adjacent leg segments are connected by flexible chitin membranes which can fold and unfold. Pairs of antagonistic muscles connecting adjacent leg segments bring about movements by their contractions.

Insect flight : Flying insects  may have one or two pairs of wings attached to their thoracic segments. They fly by moving their wings up and down independently to beat against the air. During the downstroke, the wings are pulled downwards and forwards; during the upstroke, they are pulled upwards and backwards. These strokes provide both forward thrust and uplifting power so that  the insect is propelled forwards in air.

    In most large insects, two sets of flight muscles are not attached directly to the wing bases. Instead, a vertical pair of muscles connects the roof of the thorax to the floor, and a longitudinal pair connects the front and back of the thorax. When the longitudinal muscles contract, the thoracic segment is shortened from front to back; at the same time, the vertical muscles relax.

This increases the height of the segment, causing the wings to move down. To raise the wings, the height of the thorax is decreased by contracting the vertical muscles and relaxing the longitudinal ones. These two pairs of muscles are known as indirect flight muscles.

Note : The thoracic segment is made of several separate hard plates of exoskeleton which form the roof, sides and floor, joined by strips of soft, flexible membrane.

   Each wing base is linked to an articulating surface which slides over a pivot. the articulating surface is part of the roof of the thorax, while the pivot is on the side of the thorax. This results in a very efficient lever system so that a small change in the height of the thorax brings about a large wing movement.

   A set of direct muscles attached to the floor and sides of the thorax twist and flex the wings during their flapping movement, and thus increase the uplift and the forward thrust.

When an insect soars upwards, the wings beat at a a faster rate. However, as it swoops downwards to rest, the wings beat at a slower rate. The wings of insects beat at a rate of 5 beats per second in certain large butterflies to about 400 to 500 beats per second on mosquitoes. In most grasshoppers, the wings beat at a rate of 15 to 50 beats per second.
December 15, 2018

Mouthparts of a Grasshopper





Mouth part - Function

• Mandible - Heavy, toothed, jaw like structure to cut and crush plant material

• Maxilla - Inner part of maxilla, directs food to mandibles, and also cuts and grinds the food

• Maxillary and labial palp - Sensory function

•  Labrum  - Helps to hold the food material, e.g. the leaf, in place

• Hypopharynx - Tongue like structure bearing openings of salivary glands

• Labium - Assists in manoeuvring food
December 15, 2018

The Primary Functions of Cell Organelles





Organelles  - Primary Functions

• Nucleus - Storage of hereditary information, control of cell activities

• Endoplasmic reticulum (ER)  - Distribution of proteins and  other materials throughout cell

• Ribosomes - Sites of protein synthesis

• Mitochondria - Sites  of chemical energy conversions for cell activities

• Chloroplasts - Sites of photosynthesis

• Golgi - Synthesis, Packaging and distribution of materials

• Lysosomes - Digestion , waste removal and transport of materials out of cell

• Vacuoles - Storage

• Centrioles - Involved in cell division
December 15, 2018

Differences between Plant and animals Cells





Plant Cell - Animal Cell

• Cellulose cell wall present - Cellulose cell wall absent

• Chloroplasts present - Chloroplasts absent

• A large central vacuole present - Small vacuoles may be present or absent

• Centrioles absent  - Centrioles present

• Cytoplasm less dense and found along the peripheral of the cell - Cytoplasm dense and granular, and fills cell completely

• Starch granules present - Glycogen granules present