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”
