topic 3.3

Question 1

what is immunodeficiency?

Answer 1

it occurs when the body’s immune system is unable to prevent and/or fight infections

Question 2

explain the two types of immunodeficiencies

Answer 2

1. primary - chiefly affects immune system
2. secondary - affects immune function as consequence of its effects elsewhere in body

Question 3

explain human immunodeficiency virus (HIV)

Answer 3

HIV destroys helper T cells, causing immune deficiency + increased susceptibility to secondary infections + cancer as Th control humeral and cell-mediated immune responses

Question 4

explain pathophysiology of HIV

Answer 4

• HIB infects dendritic cells in mucous membranes, which transports virus to helper T cells in lymph nodes
  2. virus replicated within CD4+ cells, slowly weakening immune system
• if CD4+ count falls below 200 cells mm3, individual has AIDS

Question 5

what is immunity?

Answer 5

the body’s ability to resist infection

Question 6

what is active immunity?

Answer 6

• occurs when body exposed actual infectious substance or to vaccine that creates own antibodies in response
• involves development of immunological memory against antigen + provides protection against subsequent exposures

Question 7

what are the two kinds of adaptive immunity?

Answer 7

1. natural (acquired through infection)
2. artificial (acquired through vaccine)

Question 8

what is passive immunity?

Answer 8

• occurs when body receives antibodies against infectious substance
• aim = provide protection against pathogen

Question 9

what are the two forms of passive immunity?

Answer 9

1. natural - e.g. baby receives nutrients through placenta + breast milk
2. artificial - immunoglobin preparations given following possible exposure to infectious pathogens

Question 10

do both active and passive forms of immunity form immunological memory?

Answer 10

no, only active forms of immunity will result in immunological memory

Question 11

what type of immunity would vaccinations resulting in no illness and the formation of antibodies be?

Answer 11

artificial active immunity

Question 12

define the immune response?

Answer 12

what occurs after exposure to an antigen and it consists of two steps, primary and secondary

Question 13

what is the primary step of the immune response?

Answer 13

after first exposure, the antigen is recognised and processed and antibodies are created. this usually is 1-2 weeks in duration

Question 14

what is the secondary step in the immune response?

Answer 14

this is when repeat exposure to the same antigen occurs. it is much more rapid and produces more antibodies than in the primary response

Question 15

in simple terms, how do vaccinations work?

Answer 15

vaccinations ‘prime’ the adaptive immune response to antigens of particular pathogens

Question 16

what is the difference between vaccination and immunisation?

Answer 16

vaccination = administration of vaccine
immunisation = immunity to infectious agent attained

Question 17

what is antiserum?

Answer 17

antiserum provides humoral products of immunity transferred from either human or animal source with pre-existing natural immunity

Question 18

what is the mechanism of action of antiserum injection?

Answer 18

injection of antiserum leads to a form of passive immunity, which provides immediate but short-term protections against harmful substances