Transmission of COVID-19 and Body's Response

Question 1

What are three methods of transmission COVID-19 adheres to?

Answer 1

1. Transmission by contact
2. Infection by droplets
3. Airbourne transmission

Question 2

Describe transmission by contact

Answer 2

Involves the spread of pathogens by actual physical contact. The contact may be direct by touching an infected person, or indirect, touching an object that has been touched by an infected individual.

Question 3

What is an example of indirect contact?

Answer 3

Indirect contact may involve an infected individual coughing or sneezing on a desk, which is then used by an uninfected person.

Question 4

Describe infection by droplets

Answer 4

Occurs when tiny droplets of moisture containing pathogenic organisms are emitted when breathing, talking, sneezing, or coughing. The droplets may be breathed in by others or may settle on food or utensils to be later ingested with food.

Question 5

Describe airborne transmission

Answer 5

When moisture in exhaled droplets evaporates, many bacteria are killed, but viruses and some bacteria remain viable and can cause infection when inhaled. As these particles are lighter, they remain viable for a greater distance than those transmitted by droplets.

Question 6

What are the 2 responses of the immune response/system?

Answer 6

1. Humoral response/antibody-mediated immunity
2. Cell-mediated response

Question 7

What is antibody-mediated immunity?

Answer 7

Provides resistance to pathogens and toxins before they enter the cell.

Question 8

Outline the steps of antibody-mediated immunity

Answer 8

1. APC presents the antigen to a specific B-cell and T-cell helper cells
2. The APC and T helper cells release cytokines which activate more B cells
3. Activated B cells undergo mitosis.
4. Most B cells become plasma cells and secrete antibodies to circulate in the blood, lymph and extracellular fluid.
5. Antibodies combine with specific antigens to form an antigen-antibody complex and destroy inactive non-self antigens.
6. The remaining clones become memory cells which circulate all tissues in case of reinfection.

Question 9

What is cell-mediated immunity?

Answer 9

Provides immunity after the pathogen has entered the cell.

Question 10

Outline the steps of cell-mediated immunity

Answer 10

1. Pathogen is engulfed by the macrophages and the APC presents the antigen on the surface
2. Help T cells only recognise antigens bound to MHC II
3. CYtokines are released by macrophages and helper T cells
4. Cytokines stimulate T cells to form clones. They are sensitised, enlarged and divide.
5. Most T cells become killer T cells or helper T cells and migrate to the place where large numbers of antigens are resent. Some become memory cells
6. Cytokines attract macrophages
7. Killer T cells release cytokines that cause the death of infected cells