Session 4: Phagocytosis, Complement, Oedema Flashcards
What happens to a microbe following adherence to a phagocyte?
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.
Complement consists of a group of serum proteins that activates what?
- Inflammation
- Destruction of cells
- Opsonisation
Are the enzyme precursors normally active?
No, they are normally active
Enzyme precursors are activated mainly by which pathway?
The “classic pathway”
What is the “class pathway” activated by?
Antigen-antibody reaction
The “classic pathway” is the C1 or the C3b pathway?
C1
The “C3b” pathway is known as the what?
What is it activated by?
The alternative pathway
Activated by reaction with antigens such as bacterial cell wall
True or false: Both the classic and alternative pathways follow the same sequence after C3
True
What happens following activation of C3?
- Inflammation
- Opsonisation
- Membrane attack complexes causes cell lysis
What is oedema?
Accumulation of an excessive amount of watery fluid in cells, tissues or serous cavities
What is lymphoedema?
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
Is lymphoedema pitting or non-pitting?
It is initially pitting, but non-pitting after initial stages
Why does lymphoedema become non-pitting?
The fluid cannot move into tissues when pressed as it becomes segregated off by fibroblasts into compartments
Is ferrous oxide (FeO) red or brown?
Red
Is Ferric Oxide (Fe203) red or brown?
Brown
During phagocytosis, macrophages oxidise _____________________ to ______________________
Ferrous oxide
Ferric oxide
Is Capillary Hydrostatic Pressure (CHP) highest at the arteriole or venous end?
Arteriole end
Is Capillary Oncotic Pressure (COP) highest at the arteriole or the venous end?
Venous end
Does high hydrostatic pressure cause fluid to leave or to enter the capillary?
To leave to capillary and move into interstitial fluid
Does high oncotic pressure cause fluid to leave or to enter the capillaries?
To enter the capillary from the interstitial fluid
Midcapillary, is the net movement of fluid in or out of the capillary? Why?n
There is no net movement midcapillary, as the hydrostatic pressure=the oncotic pressure
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?
The arteriole end: filtration out of the capillary
Midcapillary: No net movement
The venous end: Reabsorption of fluid into the capillary
What is normal arteriolar capillary hydrostatic pressure?
35mmHg
What is the normal venular capillary hydrostatic pressure?
15mmHg
Normal blood colloid oncotic pressure is what?
25mmHg
Hypoproteinemia (low blood protein) leads to what in terms of oncotic pressure?
This leads to lowering of capillary oncotic pressure which causes fluid to leave the capillary and move into interstitial fluid, presenting as oedema
At the arteriole end _______, _________ and other nutrients have the greatest concentrations in the blood and so they move ____________ by diffusion.
Oxygen
Glucose
Out
At the venous end __________ and other waste products have greatest concentrations in ________________ so they move out by ______________.
Carbon dioxide
Interstitial fluid
Diffusion
