Whole Blood, Haematology (physiology) Flashcards
What are the functions of blood? (5)
-Reduce fluid loss at injury sites.
-Immunity
-Thermoregulation
-Regulation of pH and electrolytes.
-dissolved in hormones, gases, nutrients and metabolic wastes.
Characteristics of blood (5)
Physicochemical characteristics
Colour variations
Blood pH
Blood temperature
Contribution to body weight.
How do we determine haematocrit?
Haematocrit= Height of RBC’s/ Total height
What do we call the blood cells that are not in plasma?
Formed elements
What is haematocrit?
It is the PERCENTAGE of total blood volume that is occupied by packed RBC’s.
What is packed cell volume?
It is the amount/VOLUME of the total blood volume that is occupied by packed RBC’s.
What is the clinical significance of determining PCV/Hct? (3)
It helps with diagnosis and treatment of anaemia and polycythaemia.
-Determine the hydration status
-Decision of blood transfusion
What does the value of haemoglobin reflect in the blood?
It reflect the oxygen carrying capacity of RBC’s.
What are the causes of elevated haematocrit? (6)
-Polycythaemia vera
-Dehydration
-Heart disease
-Lung disease
-Kidney cancer
-Genetic disease
What causes lowered haematocrit? (8)
-Sickle cell anaemia
-Thalassemia
-Cancer
-Kidney failure
-Autoimmune diseases
-Bone marrow disorders
-Nutrient deficiencies
-Chronic bleeding
Given Hct and plasma volume, how can we calculate blood volume?
BV= PV/1-Hct
What is erythrocyte sedimentation rate (ESR)?
It is the rate at which cells sediment (settle down).
How do we determine the ESR? (4)
-Add an anticoagulant (e.g heparin) to the fresh blood sample.
-Sample must be in a narrow vertical tube (westergen tube)
-Read the rate of sedimentation after an hour.
-Height of the cell-free, clear column of plasma at the upper level of the tube=ESR.
What is the value of the ESR that declares a pathology?
> 100mm/hr
What are the factors that affect ESR? (6)
-Blood viscosity
-Specific gravity of RBC
-Increase in the size of RBC
-RBC count
-Increased fibrinogen
-Rouleaux formation