lymphocytes

Question 1

what is the size of lymphocytes?

Answer 1

7-14 µm

Question 2

what are some features of lymphocytes?

Answer 2

• are non-granular
• have a large nucleus
• only a small amount of the cytoplasm is visible due to the size and shape of the nucleus

Question 3

what are the three different cells that a lymphoid progenitor can form:

Answer 3

1. B-lymphocyte
2. T-lymphocyte
3. Natural Killer (NK) Cell

Question 4

what is a lymphoid progenitor (aka lymphoblast)?

Answer 4

this is a precursor to other mature blood cell types such as T-lymphocytes, B-lymphocytes and Natural Killer cells

Question 5

what is a natural killer cell?

Answer 5

a large granular lymphocyte

Question 6

what type of microscope must be used to distinguish between different types of lymphocytes?

Answer 6

an electron microscope

Question 7

where are B-cells conditioned (matured)?

Answer 7

in the Bone marrow

Question 8

where are T-cells conditioned (matured)?

Answer 8

In the Thymus

Question 9

what is the common progenitor cell that T and B cells share called?

Answer 9

It is called the small lymphocyte

Question 10

what are B-lymphocytes responsible for?

Answer 10

Humoral immunity

Question 11

what are the two cell types that B-cells can differentiate into once activated?

Answer 11

• Plasma cells
• Memory B-cells

Question 12

what do plasma cells produce a lot of?

Answer 12

plasma cells produce a lot of antibodies

Question 13

what do memory B-cells function as?

Answer 13

they function as immunological memory

Question 14

how do antibodies travel?

Answer 14

antibodies travel via the body fluids such as blood, lymph and interstitial fluid

Question 15

what are body fluids all known as?

Answer 15

body fluids are also known as the humours

Question 16

what is the difference between humoral vs. cell mediated immunity

Answer 16

humoral immunity produces antigen specific antibodies and cell mediated immunity does not

Question 17

what are T-cells responsible for?

Answer 17

Cellular immunity

Question 18

what are the functions of T-helper cells?

Answer 18

• to respond to antigen presentation by “professional” cells.
• to help/mediate other leucocytes by secreting cytokines

Question 19

what are examples of “professional” cells?

Answer 19

• B cells
• Macrophages
• Dendritic cells

Question 20

what are examples of T-helper cells using cytokines on other leucocytes?

Answer 20

1. T-helper cells activating B lymphocytes
2. T-helper cells activate macrophages
3. T-helper cells regulate T lymphocyte action

Question 21

what is the function of T cytotoxic cells?

Answer 21

These cells respond to antigen presentation by “Non-professional” cells

Question 22

what is an example of a T-cytotoxic cells function?

Answer 22

The T-cytotoxic cell’s response to any nucleated cell that has been infected or damaged

Question 23

what are Natural Killer Cells a feature of?

Answer 23

innate (non-specific) immunity

Question 24

what are the functions of Natural Killer cells?

Answer 24

• provide immune surveillance
• attracted by interferon-ɑ which is secreted by infected cells
• secrete interferon-𝛄 when they attack something to stimulate macrophages

Question 25

what is immune surveillance?

Answer 25

it is when natural killer cells travel around tissues looking for cells with abnormal plasma membranes

Question 26

How can NK cells kill infected cells?

Answer 26

By releasing perforins, which create a network of pores in the cell membrane of infected cells

Question 27

how do perforins cause infected cell death?

Answer 27

they allow the free passage of ions, proteins and other intracellular material which the infected cell needs. This means the cell cannot maintain its internal environment.

Question 28

Describe the steps for NK cells killing an abnormal cell.

Answer 28

1. Recognition of abnormal cell and adhesion to cell 2. Realignment of Golgi apparatus 3. secretion of perforin 4. Lysis of abnormal cell

Question 29

what might a high count of lymphocytes indicate?

Answer 29

- Viral infection - Some leukaemia

Question 30

what might a low count of lymphocytes indicate?

Answer 30

- prolonged illness - immunosuppression - cortisol treatment