Cells and Tissues of the IS

Question 1

What are the three types of capillaries?

Answer 1

• Continuous (least permeable, most common - skin, muscles)
• Fenestrated (large fenestrations, more permeable than continuous - brain, kidney)
• Sinusoidal (most permeable, very specialised locations - spleen, bone marrow)

Question 2

Describe the key properties of Neutrophils.

Answer 2

• Rapidly deployed
• Highly expendable
• 50-70% of blood leukocytes
• approx. 7hr half life
• 1-2 day lifespan
• Only ~5% in blood circulation -> the rest stay in the bone marrow until mobilised

Question 3

Describe the key properties of Eosinophils.

Answer 3

• Make up 1-3% of circulating leukocytes
• Increased in allergic individuals and in people with parasitic worms (helminths)
• Play a role in type I hypersensitivity (hayfever, etc.)

Question 4

Describe the key properties of Basophils.

Answer 4

• Make up <1% of circulating leukocytes

- Important for initiation of inflammation, paraistic infections and allergic reactions

Question 5

Describe the key properties of Monocytes.

Answer 5

• Precursor for Macrophages and Dendritic cells
• 1-6% of circulating leukocytes
• half life of approx 1 day
• some phagocytic capability

Question 6

Describe the key properties of Lymphocytes.

Answer 6

• Make up 20-40% of circulating leukocytes
• long lived
• Recirculate from peripheral blood lymphatic system
• T & B cells -> morphologically indistinct
• It’s when these guys are activated that shit gets real

Question 7

How can you identify leukocytes?

Answer 7

Depends on which ones you’re trying to differentiate

• Morphology
• Staining
• Cell surface markers

Question 8

CD4 fun facts..?

Answer 8

• An adhesion molecule that binds MHC II molecules
• signal transduction
• usually Th+ and Tc-

Question 9

CD8 fun facts..?

Answer 9

• Binds MHC I molecules
• signal transduction
• usually Th- and Tc+

Question 10

Describe the key properties of Dendritic cells.

Answer 10

• specialise in presenting antigen to naive T cells
• derived from EITHER myeloid or lymphoid precursor
• Variable life span (days to weeks)
• MAIN ACTIVATORS OF T CELLS

Question 11

Describe the key properties of Mast Cells.

Answer 11

• Mononuclear
• Precursors are non-granulated (mast cells are granulated)
• In tissues, differentiate into mature mast cells
• Important for surveillance