blood Flashcards
vol of blood in normal adult
5.5L
how much of blood is haematocrit
45%
polycythaemia
bone marrow tumours
symptoms of polycythaemia
- red complexion
- headache
- blurred vision
- confusion
- stroke/coma
what is absolute erythrocytosis
raised RBC mass, normal plasma volume
what is apparent erythrocytosis
normal RBC mass, reduced plasma volume
plasma components
- water
- solutes
3, proteins - albumin
- globulins
- fibrinogen
what do albumins do and where are they made
made in liver, contribute to colloid osmotic pressure
what do globulins do and where are they made
made in liver and lymphoid tissue, clotting factors, enzymes and antibodies
what do fibrinogens do and where are they made
liver, forms fibrin strands for blood clotting
what does transferrin do and where are they made
liver, iron transport
erythrocytes size and conc
7-8 µm, 5 million/µl
why can erythrocytes easily pass through capillaries
they are highly flexible
how many Hb molecules in a single RBC
250,000,000
how long to RBCs survive
120 days
sites of haematopoiesis
yolk sac, liver/spleen, bone marrow
where is red bone marrow in adults
sternum, ribs and upper ends of long limb bones
how is erythropoiesis controlled
- kidneys detect reduced O2- carrying capacity of blood
- less O2 delivered to kidney so erythropoietin secreted
- erythropoietin triggers erythropoiesis by bone marrow
- additional RBCs increase O2-carrying capacity of blood
CO2 effect on RBCs
binds irreversibly to polypeptide chains, carbonic anhydrase found in RBCs
CO effect on RBCs
occupies O2 binding sites, leads to CO poisoning, Hb has 4x more affinity for CO than O2
NO effect on RBCs
vasodilator, allows blood to circulate
Fe in diet effect on blood
- absorbed by active transport
- transferrin transports Fe in plasma
- liver stores Fe as ferrin
- bone marrow uses Fe to make Hb
- spleen converts Hb to bilirubin
- liver metabolises bilirubin and excretes it as bile
3 steps of haemostasis
- vascular spasm
- formation of thrombus
- formation of blood clot
what do platelets (thrombocytes) contain
- mitochondria
- SER
- cytoplasmic granules
what secretes vWf
megakaryocytes, platelets and endothelial cells
what does vWf do upon damage
- binds to collagen
- platelets binds to it and trigger stickiness
- secretion
what do platelets secrete after binding to vWf
serotonin, ADP, epinephrine
what halts clot formation
prostacyclin, nitric acid
how does clot formation halt
- exposed collagen binds and activates platelets
- platelet factors released
- attracts more platelets
- platelets aggregate into plug
platelet function factors: Collagen
from subendothelial extracellular matrix, injury exposes platelets to collagen
platelet function factors: vWf
activated by exposure to collagen, links platelets to collagen
platelet function factors: serotonin
from secretory vesicles of platelets, activated by platelet activation, aggregates platelets
platelet function factors: ADP
from platelet mitochondria, activated by platelet activation and thrombin, aggregates platelets
platelet function factors: platelet activating factor (PAF)
from platelets/neutrophils, activated by platelet activation, aggregates platelets
platelet function factors: Thromboxane A2
from phospholipids, activated by PAF, aggregates platelets
platelet function factors: platelet-derived growth factor (PDGF)
from platelets, activated by platelet activation
what triggers fibrinogen
coagulation cascade
how do anticoagulants work
- inhibit platelet adhesion
- inhibit coagulation cascade + fibrin production
causes of coaggulation disorders
- liver disease
- cirrhosis
- vit K deficiency
- haemophilia
- low blood platelets
examples of anticoagulants
heparin, antithrombin II
how does warfarin work as an anticoagulant
blocks vitamin K which is a cofactor in factor II, VII, IX, and X synthesis
type A haemophilia
factor VIII deficiency, 80% of cases
type B haemophilia
factor IX deficiency, treated w gene therapy
4 key players in lymphatic system
- histamines
- interleukins
- bradykinin
- complement cascade
function of antibodies
- activate B lymphocytes
- act as opsonins
- cause antigen clumping
- activate antibody dependent cellular activity
- trigger mast cell degeneration
- activate compliment