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1.24.1.11 - Erythropoiesis - Coggle Diagram
1.24.1.11 - Erythropoiesis
blood
fluid
7% protein
1% other
92% water
cells
neutrophils
basophils
erythrocytes - 90% of blood cells
eosinophils
T lymphocytes
B lymphocytes
NK cells
monocytes
thrombocytes (platelets)
erythrocytes
structure
lipid bilayer
biconcave disc shape increases surface area 20-30%
elasticity/deformability - passage of capillary diameter as small as 3-4 um
failure of Na+ ion movement across erythrocyte cell membrane leads to swelling and loss if the normal biconcave disc morphology
species variation
cat
variation in size
scarce central pallor (less concave)
smaller erythrocytes
dog
central pallor
uniform size
ruminant
variation in size
crenation (spiky appearance)
camelid
ellipsoid
horse
rouleux formation - clustering of RBCs in standing blood
avian and reptile
larger
early stages are rounded and may be binucleate
nucleated
occasional cells lose their nucleus and are termed erythroplastids
features of erythrocytes
there are no organelles
no mitochondria
energy is derived by anaerobic metabolism of glucose
avoiding consumption of any oxygen they are carrying
no nucleus in mammalian erythrocytes
allows biconcave shape
increased space for haemoglobin
division stem cells
erythrocytes are metabolically active
requires energy
maintaining electrolyte gradients across plasma membrane
haemoglobin molecules
roles of erythrocytes
transport of co2 from cells to lungs
transport of o2 from lungs to cells
haemoglobin
CO2 + H20 ⇌ H2CO3 ⇌ H+ + HCO3-
hydrogen carobnate can dissolve in plasma
effect of pH on blood
haemoglobin
represents 95% of erythrocyte protein
structure
globin, two pairs of polypeptides, 2 alpha and 2 beta/gamma/delta/epsilon
central haem group containing an iron atom the can bind a molecule of o2
regions of high o2 concentration
regions of low o2 concentration
hypoxic tissues
haemoglobin also binds nitroc oxide - causes dilation of blood vessles
affinity from carbon monoxide is stronger than for oxygen
functions of the MSK system
mineral homeostasis
storage
support
blood cell formation
protection
movement
blood cell formation
haematopoiesis
process occurs in red bone marrow and spleen
red marrow founds at ends of long bones and in flat bones - ribs, pelvis, skull
continuous process of replenishment
formation of blood cellular components
white blood cells
platelets
red blood cells
erythropoiesis
from stem cells - no nucleus in mature RBCs
embryo
yolk sac
liver/spleen
shift to bone marrow in later foetal stage
adult
sinusoidal capillaries with larger intercellular gaps to allow passage of cells
inactive marrow is replaced by fat but can be reactivated from circulating stem cells
nucleus becomes progressively smaller
normoblast to reticulocyte to erythrocyte
haemoglobin levels gradually increase
formation requires
copper
folic acid
iron
vitamins b2,b6,b12
protein
iron deficiency
physiological anaemia in newborns
blood loss
internal or external parasites
haemorrhage
internal
external
erythropoetin
hormone that controls rate of erythrocyte production
source
embryonic
yolk sac, liver, kidney, spleen, bone marrow
adult
kidney
erythrocyte breakdown
aging red blood cells
become more fragile
may become swollen due to failure of normal membrane function
loss of sialic acid residues from their surface
normal lifespan of red blood cells is very variable
process
damaged rbcs phagocytised by macrophages
recycling of haemoglobin
red cell turnover in mammals bird and reptiles correlates directly with basal heat production - higher the metabolic rate = higher red blood cell turnover
lifespan of transfused erythrocytes is shorter
iron metabolism after rbc breakdown
free iron is toxic
iron molecules released from haem
conveyed to bone marrow by transferrin
stored as insoluble iron in macrophages and hepatocytes as ferritin
transferrin
serum protein involved in iron transport
ternasferrin iron complexes bind to cell surface receptors
internalisation of itransferrin-iron-receptor complex
low intracellular pH within endosomes
dissociation of iron fron trc
trc dissociate at the cel surface
ferritin
rleeases iron in a controlled fashion - buffer against iron definciency and overload
primary intracellular iron storgae prtoein keepin iron in a soluble and non toxic form
haemosiderin
iron within deposits of haemoseridin is very porly available to supply iron when needed
large seposits may lead to organ damage
intracelluilar complex of ferritin, denatured ferritin and other material
abnormal rbc breakdown
mycoplasma haemofelis
neonatal erytholysis
blood group incompatibility
maternal antibodies taken up through colostrum lyse rbcs
foals kittens
otherwise normal erythrocytes may be removed from circulation if they are infected or antibody coated