Blood L2-4 Flashcards
blood functions
gas transport/ exchange
solute distribution
immunity
body temp
blood clot regulation
acid-base homeostasis preservation
BP stability
blood constituents
erythrocytes
leukocytes
thrombocytes
soluble materials
plasma
cellular elements
plasma constituents and functions
water/ plasma proteins/ globulins/ fibrinogen
thermoregulation
transport
plasma proteins
serum albumin > large protein
liver-synthesised
osmotic pressure/ lipid and steroid hormone transport
globulins
bind/ transport ions/ hormones/ lipids
immune proteins
electrophoresis function
identifies plasma proteins for diagnostics
erythrocytes
~35% Hb
primary oxygen transport
80-96 femtolitre volume
microcytic
small RBC
found in Fe-deficiency anaemia
macrocytic
large RBC
folate-deficiency anaemia
erythropoiesis
RBC formation
26 day feedback loop
starts in bone marrow, ends in vessels
cirrhosis
disorder
causes?
progressive decrease in plasma production proteins
causes: viral hepatitis, cancer, alcoholism
number oxygen per Hb
4
haemoglobin components/ structure
4 subunits> 2 alpha, 2 beta
4 Fe-containing haem to reversibly bind O2 molecules
haem
iron-containing pigment
porphyrin ring w 1 Fe central atom
4 types of globin
alpha (2 genes on ch16)
beta (1 gene on ch11)
delta
gamma
HbA
97%
2a 2b
HbA2
~2.5%
2a 2delta
HbF
foetal
2a 2gamma
Hb binding factors
oxygen partial pressure
no. free oxygen binding sites in molecule
2 forms of Hb
taut
relaxed
taut Hb
decreasing oxygen affinity/ partial pressure
releases oxygen
relaxed Hb
increasing oxygen affin/ partial pressure
firm oxygen binding
what does Hb bind to?
O2, CO2, H+ of carbonic acid, CO, NO
haemoglobinopathies
abnormal globin chain production
thalassemia types
minor
intermediate
major
thalassemia
decreased production / absence of normal globin chains
defect at gene expression/ recessive
gross deletion of >1 globin genes
sickle cell anaemia
Glut-6-val mutation in B sub-unit
therefore polymerises at low partial pressure
causes ischaemia/ infarction
RBC life-span reduction
sickle cell trait
heterozygotes
rarely symptomatic
Glucose-6-phosphate
rate-limiting enzyme in pentose phosphate pathway required for energy and glutathione production
lacking in sickle cell RBCs
a-thalassemia
from India
a-globin deficiency
excess beta chains/ unstable b tetramers
B-thalassemia
mediterranean
b-globin deficiency
a chain excess/ no tetramers
RBC membrane damage therefore toxic aggregates at high conc
Fe overload
electrophoresis a-thalassemia
decreasing HbA
HbH presence
electrophoresis b-thalassemia
decreasing HbB
haemostasis
arrest of bleeding from a broken blood vessel
platelets
anuclear cell fragments
budded off of megakaryocytes
megakaryocyte
large bone marrow cell
thrombopoietin
hormone produced in liver/ kidney regualting megakryocyte/ platelet production
stimulates megakaryocytic extended arm via bone marrow sinusoids to vessels
no. platelets per megakaryocyte
1000-3000
platelet storage/ activation
stored in spleen
activated by sympathetic nervous system
platelet life span and end
~7-10 day life span prior to apoptosis/ phagocytosis in spleen/ liver
dense tubular system
regulates platelet activation by calcium release
thromboxane A2 synthesis site
platelet granule types
alpha > clotting mediators
delta > platelet activators/ clotting agent/ contain ADP/ Ca2+/ serotonin
vascular spasm
vessel damage releases vasoconstrictors, slowing blood flow and therefore minimising blood loss
endothelial surfaces adhere via platelets sticking to exposed collagen
platelet plug formation
von willebrand’s factor aid sticking
plug seals break in vessel lining fro compaction/ vasoconstriction/ clotting cascade stimulation
prostacyclin PG12
Normal blood vessel lining release
inhibits platelet aggregation
restricts platelet plug to damaged region
final step of blood clotting
fibrinogen conversion to fibrin (soluble> insoluble)
fibrin plug enmeshes RBC’s
cascade of reactions in clotting
fibrinogen > (thrombin)> fibrin monomers> (factor VIII)> fibrin polymer
2 thrombin stimulating pathways
intrinsic > initial stimuli exposed to collagen
extrinsic > initial stimuli blood contact exposing tissue factor
anti-clotting systems
anti-thrombin
thrombomodulin
tissue factor pathway inhibitor
thrombin receptor
anti-thrombin
inhibits clotting factors
enhanced by heparin
thrombomodulin
expressed by endothelial cells
binds thrombin
decreases coagulant effects/ inactivates factors V / VIII
tissue factor pathway inhibitor
binds to factor III/VII, prevents activation
binds factor X directly
thrombin reeptor
stimulates PGI/ NO/ ADP to inhibit aggregation
fibrinolysis
clot breakdown
fibrinolysis process
clots secrete PDGF beta, recruiting fibroblasts from surrounding tissue
forms scar tissue surrounding
plasmin fibrolytic enzyme dissolves
plasmin
tissue plasminogen factor activated > needs to bind to fibrin for activity
endothelial cell activated
clotting factors
proteases activating downstream factors
III, V, VIII glycoproteins
XIII transglutaminase
quantitative platelet defects
thrombocytopaenia
qualitative platelet defects
thrombopathy
coagulopathy
dysfunction/ deficiency of coagulation factors
acquired haemostasis disorders
renal disease
hepatic disease
vitamin K deficiency
drug-induced disorders
inherited haemostasis disorders
structural defects of vascular system
thrombotic disorder
thrombocytopaenia
thrombopathy
coagulopathy
thrombotic disorder
haemostasis alteration impairing clot formation combatting capacity
coagulopathy
deficiency of coagulation factors
haemorrhage
bruising/ contusion caused by Hb degradation to biliverdin/ bilizubin/ haemosiderin
biliverdin removal
plasmin and phagocytosis
thrombosis
excessive / unwanted clotting
thrombus
clot in vessel/ heart
embolus
detached mass able to travel in vessel
embolism
lodging of embolus
thrombo-embolism
blockage by thrombus
stenosis
abnormal narrowing of body passage
virchow’s triad
3 risk factors for thrombosis
1. blood stasis
2. vessel wall changes
3. thrombosis changes to blood
anticoagulants example
warfarin
heparin
warfarin
oral anticoagulant
inhibits vit K
heparin
injection
activates antithrombin III
when are anticoagulants used?
atrial fibrillation
aortic valve replacement
recent surgery
autoimmune diseases
thrombocytopaenia
low platelet count
thrombocytopaenia causes
autoimmune disease
drug-induced > platelet synthesis interference and immunologic destruction of platelets
clinical characteristics of thrombocytopaenia
easy bruising
petechial rash
excessive bleeding
mucous membrane bleeding
petchiae
pin-point haemorrhages w blood leakage from capillaries, ^vascular permeability/ platelet function failure
inherited coagulopathies
von willebrand’s disease
haemofilia A
haemofilia B
von willebrand’s disease
autosomal dominant
lack of VW factor
poor platelet aggregation
excessive gum bleeding
haemofilia A
x-linked recessive
factor VIII deficiency
haemofilia B
factor IX deficiency
haemofilia treatment
replacement of missing factor
blood groups
blood classification based on inherited antigenic substances on RBC surface and presence/ absence of rhesus D antigen
blood group discovery
karl landsteiner in vienna 1901 as A/B/C blood groups
RBC antigen substance
protein/ glycoprotein/ glycolipid mixture
why may someone’s complete blood group change in their life time?
infection
malignancy
bone marrow transplant
autoimmune disease
5 sugars in ABO system and most common 3?
fucose*
Galactose*
N-acetylglucosamine*
sialic acid
3 enzymes in ABO system
fucosyl transferase (FUT1)
N-acetylgalactosamine transferase (A transferase)
galactose transferase (B transferase)
2 genes in blood groups
ABO
H
ABO determination
terminal sugar structure on galactose of H substance on RBC surface
function of glycosyl transferases
transfer monosaccharides to polysaccharides
O allele encodes
truncated/ non-functional proteins
H gene
encodes fucosyl transferase/ FUT1
located on Ch19
dominant to h
bombay phenotype
hh
v rare/ no symptoms
transfuse w other hh
ABO gene
7 exon gene on Ch19
O-allele
deletioin on exon 6 > frameshift> inactive protein
A/B alleles
7 nuc substitutions
4 translate into amino acid differences in gene product
hh phenotype
no functional FUT1
May have A/B transferases
no sub. H / ABO antigens
blood type O
no A/B transferase
only H substance
blood type AB
both A/B transferase
add galactose/ N-acetylglucosamine to terminal galactose on H substance
antibodies belonging to A/B/O
A> beta
B> alpha
O> alpha/beta
agglutinogens
blood group antigens
agglutinins
antibodies against blood groups
adverse agglutinin reaction
cause RBC clumping
RBC lysis> kidney failure/ uncontrolled clotting/ circulatory shock
Rh+ genotypes
DD/ Dd
Rh- genotypes
dd
anti-Rh(D) antibodies
exposure required
destroy Rh(D)+ cells > RBC bound by IgG, engulfed by macrophages/ transported to liver/ spleen for removal
universal donor
O-
universal acceptor
AB+
newborn haemolytic disease process
Rh- mother has Rh + baby, causing anti-Rh antibody production, damaged foetal RBC w next Rh+ baby
newborn haemolytic disease symptoms
anaemia
jaundice
fatality
newborn haemolytic disease treatment
mother given anti-D immunoglobulin
class of ABO antibodies
IgM therefore don’t cross placenta