Session 4: Phagocytosis, Complement, Oedema

Question 1

What happens to a microbe following adherence to a phagocyte?

Answer 1

The microbe is ingested into a phagosome (phagocytic vesicle) which fuses with a lysosome to form a phagolysosome.
The microbe is ingested by enzymes within the lysosome.
Indigested material is discharged from the phagocyte.

Question 2

Complement consists of a group of serum proteins that activates what?

Answer 2

• Inflammation
• Destruction of cells
• Opsonisation

Question 3

Are the enzyme precursors normally active?

Answer 3

No, they are normally active

Question 4

Enzyme precursors are activated mainly by which pathway?

Answer 4

The “classic pathway”

Question 5

What is the “class pathway” activated by?

Answer 5

Antigen-antibody reaction

Question 6

The “classic pathway” is the C1 or the C3b pathway?

Answer 6

C1

Question 7

The “C3b” pathway is known as the what?

What is it activated by?

Answer 7

The alternative pathway

Activated by reaction with antigens such as bacterial cell wall

Question 8

True or false: Both the classic and alternative pathways follow the same sequence after C3

Answer 8

True

Question 9

What happens following activation of C3?

Answer 9

• Inflammation
• Opsonisation
• Membrane attack complexes causes cell lysis

Question 10

What is oedema?

Answer 10

Accumulation of an excessive amount of watery fluid in cells, tissues or serous cavities

Question 11

What is lymphoedema?

Answer 11

Swelling (especially in subcutaneous tissues) as a result of obstruction of lymphatic vessels or lymph nodes and the accumulation of large amounts of lymph in the affected region

Question 12

Is lymphoedema pitting or non-pitting?

Answer 12

It is initially pitting, but non-pitting after initial stages

Question 13

Why does lymphoedema become non-pitting?

Answer 13

The fluid cannot move into tissues when pressed as it becomes segregated off by fibroblasts into compartments

Question 14

Is ferrous oxide (FeO) red or brown?

Answer 14

Red

Question 15

Is Ferric Oxide (Fe203) red or brown?

Answer 15

Brown

Question 16

During phagocytosis, macrophages oxidise _____________________ to ______________________

Answer 16

Ferrous oxide

Ferric oxide

Question 17

Is Capillary Hydrostatic Pressure (CHP) highest at the arteriole or venous end?

Answer 17

Arteriole end

Question 18

Is Capillary Oncotic Pressure (COP) highest at the arteriole or the venous end?

Answer 18

Venous end

Question 19

Does high hydrostatic pressure cause fluid to leave or to enter the capillary?

Answer 19

To leave to capillary and move into interstitial fluid

Question 20

Does high oncotic pressure cause fluid to leave or to enter the capillaries?

Answer 20

To enter the capillary from the interstitial fluid

Question 21

Midcapillary, is the net movement of fluid in or out of the capillary? Why?n

Answer 21

There is no net movement midcapillary, as the hydrostatic pressure=the oncotic pressure

Question 22

What, in terms of fluid movement, is the result of the differences in hydrostatic and oncotic pressure at the arteriole end, the middle of the capillary and the venous end?

Answer 22

The arteriole end: filtration out of the capillary
Midcapillary: No net movement
The venous end: Reabsorption of fluid into the capillary

Question 23

What is normal arteriolar capillary hydrostatic pressure?

Answer 23

35mmHg

Question 24

What is the normal venular capillary hydrostatic pressure?

Answer 24

15mmHg

Question 25

Normal blood colloid oncotic pressure is what?

Answer 25

25mmHg

Question 26

Hypoproteinemia (low blood protein) leads to what in terms of oncotic pressure?

Answer 26

This leads to lowering of capillary oncotic pressure which causes fluid to leave the capillary and move into interstitial fluid, presenting as oedema

Question 27

At the arteriole end _______, _________ and other nutrients have the greatest concentrations in the blood and so they move ____________ by diffusion.

Answer 27

Oxygen Glucose Out

Question 28

At the venous end __________ and other waste products have greatest concentrations in ________________ so they move out by ______________.

Answer 28

Carbon dioxide Interstitial fluid Diffusion