what are the different elements of blood
plasma (water, proteins, solutes)
red blood cells (RBCs/ erythrocytes) - carry O2, CO2, buffer pH
white blood cells (WBCs / leukocytes) - immune defence
platelets (thrombocytes) - clotting
what’s hematocrit
the percentage of blood volume occupied by packed RBCs
How is hematocrit calculated?
Blood is centrifuged, RBCs settle at bottom, % of total volume occupied by RBCs = hematocrit
What is hematocrit used for?
indicator of oxygen-carrying capacity and to detect anemia, polycythemia, dehydration, etc
What is the composition of plasma?
92% water
7% plasma proteins
1% solutes (ions, nutrients, wastes, hormones, gases)
What is the main function of plasma proteins?
maintain colloid osmotic pressure, pH buffering, transport, clotting, immune defense
What would happen if someone did not have enough plasma proteins?
water would leave blood vessels, oedema (swelling) because osmotic balance is lost
What are the 3 main classes of plasma proteins?
- albumin (transport, osmotic pressure)
- globulins (a, B transport/clotting; y = antibodies
- fibrinogen (clotting; absent in serum)
What’s the difference between plasma and serum?
- plasma = has clotting factors (fibrinogen)
- serum = plasma without clotting factors
What are the 3 main functions of RBC
- carry O2 (hemoglobin)
- carry CO2 ( as bicarbonate or carbamino-Hb)
- buffer blood pH
Explain the 2 concepts that allow us to have an S-shaped dissociation curve
hemoglobin subunits switch between R-state (high O2 affinity) and T-state (low O2 affinity)
cooperatively: once one O2 binds, others bind more easily; once one is released, others release more easily
What does “oxygen saturation” represent on a dissociation curve?
the % of hemoglobin binding sites occupied by O2 at a given partial pressure
Would you rather see a right shift or a left shift of your oxygen dissociation curve?
right shift = lower Hb affinity - easier O2 unloading in tissues (good during exercise, fever, low pH)
left shift = higher Hb affinity - harder to unload O2 (bad for tissue oxygenation) so physiologically, a right shift is preferred in active tissues
Draw an oxygen dissociation curve
- X-axis: pO2 (mmHg, 0-100)
- Y-axis: O2 saturation (%)
- S-shaped curve: ~100% sat at 100 mmHg (lungs), ~75% sat at 40mmHg (tissues), ~20% sat at 20mmHG (active tissues)
Explain / draw the pathway controlling the production of RBC
- low O2 - kidney produces EPO - bone marrow increases RBC production
- once O2 restored - EPO production decreases
Explain the physiological processes responsible for the change in colour of a bruise
RBC break - Hb released - broken into biliverdin (green) - then bilirubin (yellow) - finally absorbed/healed
Name 3 physiological factors that might lead to an anemia diagnosis
- nutrient deficiency (iron, folic acid, B12, B6)
- increased RBC destruction (e.g. Vit E deficiency, sickle-cell)
- blood loss or low EPO
What is the difference between macrocytic and microcytic anemia?
- macrocytic: large RBCs ( B12, folate deficiency)
- microcytic: small RBCs ( iron deficiency, impaired Hb synthesis
Why wouldn’t we all want to have polycythemia?
too many RBCs - blood to viscous - poor perfusion, increase risk of clots
WBC are separated in granulocytes and agranulocytes. explain the difference
- granulocytes (have granules): neutrophils, eosinophils, basophils
- agranulocytes (no granules): monocytes, lymphocytes
Name the main function of the WBC covered in lecture
- neutrophils: phagocytose bacteria, release enzymes/pyrogens
- eosinophils: fight parasites, allergy involvement
- basophils: allergies, inflammation, release histamine/heparin
- monocytes: differentiate into macrophages/dendritic cells
- lymphocytes: acquired immunity (B = antibodies, T = cell-mediated, NK = innate killing)
What are the 4 steps of diapedesis?
- cytokine release/chemokine attraction
- rolling (weak binding to selectins)
- firm adhesion (integrins)
- migration (pseudopodia through vessel wall)
What is the difference between innate and acquired immunity?
- innate: fast, non-specific, no memory (macrophages, neutrophils, NK, barriers)
- acquired: slow (first exposure, specific, has memory (B/T cells)
Name 4 components of innate immunity
- physical/chemical barriers (skin, mucosa)
- cellular defenses (macrophages, neutrophils, NK, mast cells)
- soluble factors (complement, cytokines, interferons)
- inflammation response
