WEEK 3: Blood Flashcards
What are the first key function of blood essential for survival?
- transport dissolved gas, nutrients, hormones & metabolic waste around the body.
What are the second key function of blood essential for survival?
regulate pH and ion composition in interstitial fluids by diffusion of ions and absorption acids
What are the third key function of blood essential for survival?
restrict fluid loss at injury sites through clotting
What are the fourth key function of blood essential for survival?
defense against toxins & pathogens through action of white blood cells
What are the fifth key function of blood essential for survival?
stabilise body temp by absorbing heat generated by active skeletal muscles
plasma VS serum?
plasma contains clotting factors, serum lacks fibrinogen hence does not clot
what is haematocrit
a measure of the proportion of red blood cells in plasma
If haematocriit is low, what does that suggest
iron deficiency
high haematocrit can also suggest what?
dehydration
What are the constituents of blood? (plasma + brief explanation of why)
plasma:
water (circulatory volume and medium 4 dissolved solutes) , electrolytes (volume regulation osmolarity, pH regulation, membrane potential) , nutrients (amino acids, lipids, sugars, metabolic wastes, hormones, O2) , plasma proteins (immunoglobins, albumin, pH buffering)
What are the celullar elements in blood?
- red (no nuclei) and white blood cells, lymphocytes, monocytes- become tissue macrophages and absorb foreign pathogens, neutrophils- destroy and engulf invading bacteria, eosinophils, basophils- involved in allergic response , platelets - important in haemostasis
Describe the 5 steps that occur when a decrease in blood flow occurs
- kidney detects low O2 carrying capacity of blood
- kidneys secrete erythropoietin into blood
- erythropoietin stimulates erythropoiesis by bone marrow
- additional circulating erythrocytes increase O2 carrying capacity of blood
- increased O2 carrying capacity relieves initial stimuli that triggered erythropoietin secretion
What makes up a higher proportion in blood cells?
neutrophils (60-70%) and lympocytes (25-33%)
erythrocyte and platelets
What makes up a lower proportion in blood cells?
eosinophil, basophil, monocyte,
respectively, how long does a leukocyte, lymphocyte erythrocyte and platelet live?
6 hrs- days, decades, 120 days and 8 days respectively
what is haemostasis?
the process by which blood clots to prevent excessive bleeding
What are the components of blood clotting?
platelets, coagulation factors and fibrinolytic factors work together to maintain hemostasis (stopping bleeding)
What is the process of hemostasis?
- platelets activate and adhere to injury site
- coagulation factors convert fibrinogen into fibrin - forming an insoluble mesh
- platelets contract, tighten the clot and stop blood flow
- thrombin is the key enzyme in this cascade-driven process
What genetic disorder can affect blood clotting
- Hemophilia
- Von willebrand disease
- they impair clot formation and can lead to excessive bleeding
what is a coagulation cascade?
the process of blood clot formation
How and why do platelets activate when injured?
Platelets go from inactive (round/smooth) to activated (irregular/sticky) upon injury, allowing them to form a plug at the injury site.
How is fibrinogen converted into fibrin
through thrombin, an enzyme that allows formation of a stable clot
what two pathways can a coagulation cascade follow?
Intrinsic pathway: activated by internal trauma in blood vessel
Extrinsic pathway: activated by external damage exposing tissue factor
What happens to the intrinsic and extrinsic pathway?
they converge into the common pathway and lead to thrombin activation-> convert fibrinogen into fibrin mesh -> stabilise the clot
Briefly explain and list three anticoagulant mechanisms
Warfarin: vit K antagonist that blocks synthesis of clotting factors
Dabigatran: directly inhibits thrombin, preventing fibrin formation
Heparin: activates antithrombin III, inhibits thrombin and prevents clot formation
What is the relevancy of anticoagulants?
They help prevent excessive clotting, by targetting steps of the cascade hence ensuring proper wound healing while preventing dangerous clots like thrombosis
