Lecture 9 Flashcards
What can the fluid material circulation the cardiovascular system do
maintains homeostasis
What does Plama contain
v Rich in protein – albumin, globulins, Ig, fibrinogen v Regulatory substances, nutritional substances, salts, waste v Removal of fibrinogen-fibrin → serum
What are the percentages of material in plasma
• 90-92% water. • 6-7% proteins • Albumin – colloid osmotic pressure • Globulin – enzymes, antibodies • Fibrinogen – polymerizes into fibrin during coagulation or clot formation • 2-3% • Fats • Carbohydrates (glucose) • Electrolytes » Bicarbonate, calcium, chloride, magnesium, phosphorus, potassium, sodium • Gases (O2, CO2) • Chemical messengers
What is the name for red blood cells
erythrocytes
what is the name for white blood cells
- leukocytes
What are the amount of RBC(erythrocytes) in mammals
v Present in large numbers (500-1000 x > leukocytes)
v Measured in millions (106/mm3 (µl), 109/ml or 1012/L)
v Variation in number (6-14 x106/mm3) and size (4-12 µm) in
domestic species
v RBC number varies in an individual
• nutritional state, physical activity, age
What is the structure composition of RBC
v commonest blood cell v Water (60%) + haemoglobin (40%) v Biconcave disk – maximises surface area v No nucleus in mammals (exceptions – foetus) v Stains eosinophilic v Ultrastructure: • homogenous, electron dense • no organelles in mature mammalian RBC • Haemoglobin
What is the function of RBC
v Carry O2, CO2 & H+ (buffering role)
v Life-span is about 80 d in cats; 100-
120 d in dogs & humans; 150 d in
horses, cattle & sheep
What are Reticulocytes
immature red blood cells v 1% of the red cells in the human body. v develop and mature in the red bone marrow v circulate for about a day in blood before developing into mature RBC v Mammalian reticulocytes do not have a cell nucleus v Mammalian reticulocytes do have a reticular (mesh-like) network of ribosomes (basophilic stain) v Increase in circulating reticulocytes indicates increased RBC production
What animal’s RBC lose their nucleus and mitochondria
mammals
What was the reason for losing nucleus and mitochondria
v Allows them to carry more haemoglobin, and
more oxygen
• Doesn’t seem to be a problem in other groups
• Birds do have air sacs
v Bi-concave disc aids diffusion
v No mitochondria, so don’t use the oxygen
they carry
• Produce energy by glycolysis
v Short answer – we don’t know why
mammalian RBC loose their organelles
How oxygen can a haemoglobin carry
4
Where does majority of the CO2 go to
89% go to erythrocyte
11 go to the blood
How does CO2 enter the cell
Aquaporin (AQP1)
Rhesus
Why can RBC carry CO2
Most is transported by the RBC as bicarbonate ions or combined with haemoglobin v RBC have high levels of carbonic anhydrases so more bicarbonate is produced than in plasma v Cl-HCO3 exchanger transports bicarbonate out of RBC, promoting formation of more bicarbonate within the RBC
How do CO2 cross the RBC plasma membrane
Classical membrane
diffusion
v Diffusion through pores –
“gas channels”
What are involved in haemostasis (clotting)
platelets
Structure of platelets
v Small, ovoid bodies
v Cytoplasmic pieces ‘budded off’ from
megakaryocyte
Lifespan of platelets
Lifespan 8-10 days (sequestered in the
spleen)
What is the composition of the platelet granules
• Dense granules
v ADP, serotonin (a vasoconstrictor), calcium
• Alpha granules
v Thrombospondin, fibrinogen
How does platelets clot blood
aggregation and coagulation
What is aggregation for blood clotting
platelet adherence
Aggregation – associated with endothelial cell injury;
formation of platelet plug
What is coagulation for blood clotting
fibrin formation
– initiated at larger sites of injury;
formation of a clot (thrombus)
What events does injury trigger
2 events v The activation and deposition of platelets at a wound site v Activation of the coagulation pathway • Prothrombin converted to thrombin • Thrombin causes fibrinogen to polymerize into fibrin v These lead to the formation of a fibrin seal on the deposited platelets v “Plugs the leak”
What is haematocrit
Packed cell volume (PCV),
What are Haemopoietic stem cell (HSC)
multipotent cell
v they can form any
blood cell line
v Myeloid and lymphoid
How do the stem cell differentiate
Controlled by lineageindependent and
lineage-specific
cytokines and growth
factors
What is the role of hamopoiesis
• To maintain homeostasis:
v Short lifespan of mature blood cells requires continual
replacement throughout life
• Enable a rapid response to life-threatening conditions
:
v Blood loss
• RBC numbers are tightly regulated
v Infection
• WBC numbers increase to fight infection
What cells need to be removed and replaced?
dangerous cell types:
v Neutrophils and eosinophils
• Once activated they are damaging to surrounding tissues
Where are the sites of haomopoiesis for embryo
Yolk sac, liver and spleen
Where are the sites of haomopoiesis for foetus
Liver, spleen and bone marrow
Liver, spleen and bone marrow juvenile
• Bone marrow – reducing sites with age
• Bone marrow – reducing sites with age adult
Bone marrow – proximal ends of
femurs, pelvic flat bones, vertebrae
skull, ribs and sternum
What does haemopoietic stem cells (HSC) interact with in the bone marrow
v Stromal fibroblasts
v Osteoblasts
v Endothelial cells
v Extra-cellular matrix
What does receptors on HSC bind to
v Stromal adhesion molecules
v Membrane bound stromal growth
factors
v Soluble growth factors
What does receptor binding control
gene
expression and directs development
What cause erythrorpoiesis? (differentiating into erythrocyte)
Stimulated by
erythropoietin (EPO
What causes thrombopoiesis?? (differentiating into megakarycyte)
Stimulated by
thrombopoietin (TPO)
What is erythropoiesis controlled by
controlled by erythropoietin (EPO) produced by fibroblast-like cells in the cortex and outer medulla of the kidney v Shortens cell cycle time v Increased rate of maturation v Increased rate of release from bone marrow
When does exocytosis of nucleus happen during erythropoiesis?
When normoblast form into reticulocyte
When does the mitochondria and ribosomes be lost
When Reticulocyte form into erythrocyte
What does increase presensce of circulating reticulocytes
Indicative of recent increase in
erythropoiesis
What does Decrease in oxygen delivery to tissues leads to
o tissues leads to the
p
What causes Decreases in oxygen level (hypoxia)
§ Low blood volume § Anaemia § Low haemoglobin § Poor blood flow § Pulmonary disease
Anaemia
reduction in the ability of blood to carry oxygen
Polycythaemia
abnormally increased number of RBC
v Bone marrow cancer or abnormal erythropoietin production
Erythrocytes
Oxygen and carbon dioxide transport
Platelets
Haemostasis
Erythropoiesis
Role of hypoxia and erythropoietin
