Human Health and Diseases — BIOLOGY STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYHuman Health and Diseases5 Marks
Question
Describe different ways in which epithelial surface offers the innate immunity.
✓
Answer
Skin and mucous covering, when intact protects the body against the invasion by pathogens. The healthy skin has bactericidal activity due to the salts present in drying sweat.
Sebaceous glands in the skin produce secretions and long chain of fatty acids. These are bactericidal and fungicidal.
Respiratory tract is provided with mucosa which prevents entry of microorganisms to a large extent.
The inhaled particles are arrested through hair in the nasal passage. The particles that pass beyond nasal passage are caught by mucus lining the epithelium. They are swept back to pharynx. Then they are either swallowed or coughed out.
The cough reflex is an important defence mechanism of respiratory tract.
There is saliva in the mouth which has inhibitory effect on microorganisms. Gastric secretions has acidity and hence microorganisms are destroyed in stomach.
The flushing action of urine eliminates bacteria from the urethra. Semen too has antibacterial substances, e.g. Spermine and zinc.
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