Blood Flashcards
Average circulating blood volume in adult make
5L: 1L in lungs, 3L in systemic venous circulation, 1L in heart and arterial circulation
Functions of blood
- Carriage of physiologically active compounds (plasma)
- Clotting (platelets)
- Defence (WBC)
- Carriage of gas (RBC)
- Thermoregulation
- Maintenance of ECF pH
Composition of Blood
- Plasma (4% body weight and 95% water 5% P/ions/nutrients (glucose))
- RBC
- WBC
- Platelets
Explain plasma in more detail
Circulates biologically active molecules and compounds with its composition normally kept within strict limits.
How are plasma proteins subdivided?
- Albium - abundant (60%) - is transpost protein/vehicle for lypids and fat soluble proteins/vitimans
- Globulin - subdivided into a, B, gamma globulins (48%) - help transport lipids and fat soluble vitimans
- Fibrinogen and other clotting factors (2%) - clotting process
plasma P not taken up by cells but perform their functions in the circulations (unlike hormones which use blood as a vehicle)
Colloid Oncotic Pressure
Plasma P can’t cross capillary membrane so displace water, creating a grad that pulls water into plasma from ISF (osmosis).
Net direction of movement determined by balance between colloid oncotic pressure (favours movement into capillary) and capillary hydrostatic pressure (blood pressure) which favours movement out of capillary.
results in conc of fluid remainign unchanged although volume of Plasma and ISF alters - ISF acts as fluid resivoir
Hypoproteinaemia
Abnormally low levels of circulating plasma protein
Causes: prolonged starvation, liver disease. intestinal diseases, nephrosis
Common characteristic: oedema due to loss of oncotic pressure
Explain Erythrocytes
Red Blood Cells:
Most abundant with a lifespan of **120 days **- highly flexible, biconcave, non-nucleated, become more ridged with age
Densely packed with haemoglobin, with O2 saturation determining colour
What is Eythropoiesis
RBC Formation: controlled and accelerated by hormone erythropoietin
Describe Leukocytes
White Blood Cells: nucleated and larger than RBC and involved in defence against pathogens
List all the WBC
WBC:
* Granulocytes
Neutrophils
Eosinophils
Basophils
* Argranuloyctes
Monocytes
Lymphocytes (B cells and t cells (T helper and T killer cells))
Give facts of Leukopoiesis
White Blood Cell Formation: controlled by a cocktail of cytokines (proteins/peptides released from one cell type which act on another)
* Colony Stimulating Factors (e.g. Granulocyte CSF)
* Interleukins
Explain process of Leukopoiesis
Cytokines are released from mature WBC and stimulate both mitosis and maturation of leukocyte.
Differential stimulation of leukopoiesis in response to infection:
* Bacterial inc neutrophils
* Viral inc lymphocytes
Thus, cytokine cocktail is dynamic, changing its compostion in response to infection to infulence which WBC will be preferentially stimulated.
Explain platelets (as part of the composition of blood)
Not cells; membrane bound cell fragments (from megakaryocytes) and rarely nucleated - formation goverened by Thrombopoietin.
Haematocrit
Measures proportion of RBC in blood