Human Biology First Stage LAB:5 - PDF

Human Biology First Stage LAB:5 human body protection Assistant Lecturer Dunya.A.Mohammed human body protection... The line of defence includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include : ❖ Skin is the oute...

Human Biology First Stage LAB:5 human body protection Assistant Lecturer Dunya.A.Mohammed human body protection... The line of defence includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include : ❖ Skin is the outer covering of the body. it protects everything inside the body. It acts as a barrier between invaders (pathogens) and your body. ❖ Tears, mucus and saliva your nose, mouth and eyes are obvious entry points for pathogens. However, tears, mucus and saliva contain an enzyme that breaks down the cell wall of many bacteria. ❖ Cilia very fine hairs (cilia) lining your windpipe move mucus and trapped particles away from your lungs. Particles can be bacteria or material such as dust or smoke. ❖ Stomach acid kills bacteria and parasites that have been swallowed. ❖ Urine flow Your urine flow flushes out pathogens from the bladder area. ❖ Neutrophils these are white blood cells that can find, kill and ingest pathogens seeking an entrance into the body. These cells primarily attack bacteria. ❖ T helper cells these cells are like the bosses. They give instructions to other cells by producing signals. Each T helper cell only looks out for one type of pathogen. ❖ Cytotoxic (killer) T cells these are killer cells. They punch holes in the walls of the pathogen cell so that the contents ooze out. ❖ Macrophages these cells ‘eat’ (ingest) or clean up the mess of dead cells. ❖ B cells these produce antibodies, which lock onto the antigen of invading bacteria and immobilise them until the macrophage consumes them. Some B cells become memory cells after being activated by the presence of antigen. These cells are able to live for a long time and can respond quickly following a second exposure to the same antigen. Immunity -The state of being resistant to reinfection with a pathogen -The state of protection against foreign pathogen Antibody Antibody, also called immunoglobulin, are Y-shaped proteins that are produced by the immune system in response to the presence of a foreign substance, called an antigen. Antibodies recognize and latch onto antigens in order to remove them from the body. A wide range of substances are regarded by the body as antigens, including disease- causing organisms, viruses, bacteria and toxic materials or other chemicals.  Antigen is any substance that stimulate immune system to produce antibodies against it. Antigens include toxins, chemicals, bacteria, viruses, or other substances that come from outside the body. Body tissues and cells, including cancer cells, also have antigens on them that can cause an immune response. Hormone A chemical substance produced in the body that controls and regulates the activity of certain cells or organs. Many hormones are secreted by special glands, such as thyroid hormone produced by the thyroid gland. that are secreted directly into the blood, which carries them to organs and tissues of the body to exert their functions. Hormones are essential for every activity of life, including the processes of digestion, metabolism, growth, reproduction, and mood control. Enzymes Are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells. They serve a wide range of important functions in the body, such as aiding in digestion and metabolism. Some enzymes help break large molecules into smaller pieces that are more easily absorbed by the body. Other enzymes help bind two molecules together to produce a new molecule.