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
Viscosity
How thick/sticky blood is compared to water.
Plasma x1.8 thicker than water
Whole blood x3-4 thicker than water
What can viscosity depend on
- haematocrit - 50% inc in haematocrit inc viscosity by approx. 100%
- Temperature - inc in temp dec viscosity (vica versa)
- Flow rate - dec flow rate inc viscosity (vica versa)
Define Oncotic Pressure
the osmotic pressure generated by large molecules (especially proteins) in solution
Factors responsible for generation of oncotic pressure
Oncotic pressure, or colloid osmotic-pressure, is a form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel’s plasma (blood/liquid) that causes a pull on fluid back into the capillary.
Lifespan of Platelets
10 days
Function of RBC
Carry O2 from lungs to rest if body along capillaries, taking waste (CO2) back
Function of Erythropoietin
Hormone that is produced predominantly by interstitial cells in the kidney. Once it is made, it acts on red blood cells to protect them against destruction. At the same time it stimulates pluripotent stem cells of the bone marrow to increase the production of red blood cells (erythroblast or immature RBC).
Factors to inc secretion of erythropoietin
haemorrhage, anaemia, cardiac dysfunction, lung disease —> secretion enhanced when O2 delivery to kidneys is reduced (hypoxia).
Give the classifications of WBC
Defined by appearance on cytoplasm:
Granulocytes and include Basophils, Eosinophils and Neutrophils.
Agranulocytes, includes Lymphocytes and Monocytes.
Make diagram of each type of WBC
Okay!
Define/compare moncyte and macrophage
- Monocyte - a large phagocytic white blood cell with a simple oval nucleus and clear, greyish cytoplasm.
- macrophage - a large phagocytic cell found in stationary form in the tissues or as a mobile white blood cell, especially at sites of infection.
Monocyte and macrophage are two types of cells found in the immune system of organisms. They are considered as the front line of host defense. Monocytes are bean-shaped small cells whereas macrophages are irregular-shaped large cells. Both monocytes and macrophages are capable of secreting cytokines and chemokines
Unique function of platelets
Adhere to damaged vessel walls and exposed CT to mediate blood clotting (don’t adhere to healthy intact endothelium) - prevent and stop bleeding
Role of Thrombopoietin in platelet formation
Regulates the production of platelets. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that bud off large numbers of platelets.
Give normal haematocrit values and state how they might change in certain circumstances?
normally 40-50%
Changes with altitude, dehydration, anemia, large number of white blood cells due to long-term illness, infection or a white blood cell disorder such as leukemia or lymphoma, vitamin or mineral deficiencies, recent or long-term blood loss.
Colloid oncotic pressure definition
form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel’s plasma (blood/liquid) that causes a pull on fluid back into the capillary.
capillary hydrostatic pressure
capillary hydrostatic pressure favours the movement of fluid out of the blood vessel
