RBC's & Haemostasis Flashcards
Describe the relative proportions of oxygen carried in the blood via Hb and dissolved in plasma.
70x oxygen bound to Hb than dissolved in plasma.
What type of respiration occurs in Hb and how does its efficiency compare to a normal somatic cell.
How much of a RBC is Hb in terms of a) dry mass b)wet mass?
Anaerobic as it lacks organelles including mitochondria.
Glucose is decarboxylated to product 2xlactate and 2ATP compared to 36ATP molecules generated in aerobic respiration.
a) 95%
b) 35%
Describe the structure of Hb and how it differs to foetal Hb.
Hb is a tetramer composed of 4 subunits; 2 alpha + 2 beta
Each subunit is bound to a haem group.
Foetal Hb also has 4 subunits; 2 alpha + 2 gamma
Foetal Hb has a greater affinity for oxygen
Adults have a very low percentage of foetal Hb.
Describe the haem group in Hb.
The haem group is responsible for oxygen transport, it is a porphyrin ring which makes it rigid, 2D and highly coloured due to the sharing of electrons. It is also conjugated to a ferrous group (Fe2+)
Describe the Bohr effect.
Takes place response to high carbon dioxide partial pressure.
High CO2, decreases the pH of the blood and this leads to a decreased affinity of Hb for O2 causing dissociation to respiring tissues.
Outline the respiratory thresholds.
What happens in order for the body to increase respiratory drive?
95- normal
90-poor
88- critical. INCREASE RESP DRIVE
H+ ions detected in cerebrospinal fluid.
CO2 is a gas and can travel to CSF quickly where it reacts with blood to form carbonic acid and H+ ions. In this sense an increase respiratory drive is more dependent on CO2 concentration than H+ ions in blood as it takes longer for these to be detected as they are only detected in the carotid bodies.
Describe the appearance, function, frequency and location of erythrocytes.
Appearance: Red (oxy-HB), 2umx7um, biconcave
Function: transport O2/CO2, lifespan approx. 120 days, flexible and stack themselves in vessels
Frequency: 5million/uL. PCV: 40-52% women; 36-48% men
Location: post birth- bone marrow. >20yo- membraneous bone
Describe the cell lineage that cells follow in haematopoeisis.
Multipotent haematopoietic stem cell (Haemotocytoblast)
Common myeloid progenitor
Reticulocyte
Erythrocyte
What is erythropoietin and how may it be used in the “real world”?
Cytokine which drives erythropoiesis. Made in kidney in response to kidney hypoxia.
Performance enhancer.
Describe what a Reticulocyte is.
How can detection of is help us find out whats going on in the blood?
Erythrocyte precursor cell
Still contains nucleus and organelles.
Lifespan- 2 days
Low reticulocyte count means low levels of erythropoiesis taking place
High reticulocyte count may indicate haemolytic anaemia.
Describe Methaemoglobinamia
Condition in which iron(II) in Hb is oxidised to iron(III) and thus unable to transport oxygen.
CAUSES:
- congenital globin mutations
- NADH hereditary diseases
- toxic agents
Describe Polycythaemias, both physiologically and pathologically.
Increases blood volume due to increased RBC’s. Also increases viscosity
Physiologically: in people that live at high altitudes.
Pathologically: clog blood vessels (risk of thrombosis), asymptomatic, no cure, all ages. JAK2 mutation.
Describe the bodies iron requirement.
65% iron in body in Hb. 30% intracellularly stored in FERRITIN(very easily accessible) in liver, bone marrow and blood and HAEMOSIDERIN (less accessible). 4% IN myoglobin
Iron stored in reticuloendothelial system in spleen, liver, RBCs, WBCs, bone marrow
Usage: 1mg/day (excpetions, menstruation, pregnancy, peptic ulcers)
What is the use of Vitamin B12 & Folic acid?
Important in fast dividing tissues (growth)
- DNA formation
- Nuclear maturation
- RBC’s, skin, gametogenesis,
Describe a type of anaemia caused by Folic acid & Vit-B12 defence?
Megaloblastic anaemia
Other causes - lymphoma, old age, diet, malnutrition, veganism
Treatment-
Oral folic acid
Intramuscular hydroxocobalamin