Pharm2812 Exam

SECTION B: SHORT ANSWER QUESTIONS

1. Give four non-specific host defence mechanisms. Explain how each acts to keep us healthy.  Mechanism and Explanation:

Non- specific host defences protect us against any pathogen regardless of species. They can be physical, chemical or biological:

Physical Barriers:

• Skin:

• Dry, acidic environment helps prevents growth
• Dead cells (keratin cells)discourage colonisation
• Normal flora of the skin competes with bacteria

• Flushing Mechanisms:

• Lacrimal apparatus: a group of structures that manufactures and drains away tears thus inhibiting colonisation of microbes on the eye.
• Saliva: helps dilute microorganisms in the mouth and wash them away
• Urine: cleansing of the urethra by the flow of urine.

Chemical Barriers:

• Proteins:

• Complement: group of proteins in plasma. Circulate body in inactive form until activated by foreign substances; promote inflammation and lysing of cells.
• Interferon: anti-viral proteins that protect neighbouring cells by binding to them and stimulating further production of anti-virals.

Biological Barriers:

• Inflammation:

• Acute inflammation: response is intense for a short period of time. Usually a result of tissue injury and infection. Steps are:

1. Increase blood flow
2. Rise in temp
3. Fibrin clots which isolates site
4. Phagocytic action continues until bacteria destroyed

• Chronic inflammation: response less intense, long lasting and difficult or impossible to remove.

2. Give two specific host defence mechanisms. Explain how each acts to keep us healthy.  Mechanism and Explanation:

Specific host defences include production of proteins called antibodies and specialised lymphocytes:

• Humoral Immunity:

• Involves production of antibodies by B-cells
• Defends primarily against bacteria, bacterial toxins and viruses
• Stimulation of B-cells by an antigen results in product of long-term memory cell.

• Cell Mediated Immunity:

• Involves specialised lymphocytes called T-cells
• T-cells regulate activation and proliferation of other immune cells such as macrophages
• Effective against bacteria and viruses

• Cytokines: chemical messengers in immune system.

3. Give four major factors that contribute to the emergence of infectious diseases. Explain how each factor is involved. Factor and Explanation:

• Human demographics and behaviour e.g. age, hygiene, socio-economic status
• International travel and commerce e.g. spread of disease
• Microbial adaption and change e.g. antibiotic resistance
• Breakdown of public health measures e.g. tuberculosis

4. Give four factors that have contributed to the rise of tuberculosis in recent years and explain how each has contributed to this rise. Factor and Explanation:

• HIV: unsafe sex, drug use, sharing of needles
• Movement of people
• High risk populations
• Breakdown of public health measure: Poorly managed programmes

5. Cell morphology can be used to classify bacteria. Draw and name the FIVE most common morphologies of bacterial cells. Give an example of a bacterium with each morphology (state the genus and species name).