The defense system of the human body is made up of entire organs and vessel systems like the lymph vessels, but also of individual cells and proteins. The inner and outer surfaces of the body are the first barriers against pathogens (germs). These surfaces include the skin and all mucous membranes, which form a kind of mechanical protective wall.
Several things support this protective wall:
<span><span>- The body’s own antibacterial substances can disable different pathogens from the environment at an early stage. A certain enzyme found in saliva, the airways and tear fluid destroys the cell walls of bacteria.
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- Many pathogens that are breathed in get stuck to mucus in the bronchi and are then moved out of the airways by hair-like structures called cilia.
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- Most pathogens that enter the body together with food are usually stopped by stomach acid.
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- Normal flora, harmless bacteria that reside on the skin and many mucous membranes in the body, also help to protect the body.</span></span>
The cough and sneeze reflex can also help to remove pathogens.
Hope this helps (:
Answer:
Unconditioned stimulus.
Explanation:
Classical conditioning may be defined as a type of learning procedure in which the biological procedure is used to pair up with the previous nerve stimulus. This stimulus result in the response of an individual.
The Pavlov experiment with the dog explains the process of classical conditioning. The ringing of bell (conditioned stimulus) is paired with unconditioned stimulus (meat presentation).
Thus, the meat presentation is unconditioned stimulus.
The correct answer is mitosis.
Mitosis is a part of the cell cycle and it is actually a cell division. The mother cell is divided to produce two new genetically identical daughter cells. It is important that during the mitosis is that each daughter cell gets a full set of chromosomes.
