BIO 235 Assignment 3

Assignment 3 Weight: 5% Minimum Pass Grade: 50% Each question is worth 10 marks. 1. Fill in the words or phrases that best complete each sentence. Be as specific as possible. 1. Erythrocytes contain the enzyme carbonic anhydrase, which catalyzes the conversion of metabolically produced CO2 and water into carbonic acid. 2.Most old erythrocytes are removed from circulation and destroyed by cells called machrophages, as they rupture passing through the narrow capillaries of the organ called the spleen, liver and red bone marrow. 3.Undifferentiated cells called stem cells reside in the bone marrow, where they continuously divide and differentiate to give rise to each of the types of blood cells. 4.The process of leukocytes squeezing through the capillary walls to exit the vasculature is known as diapedesis. Once they leave the bloodstream to fight a pathological condition, they never return 5.The genetically-determined glycoprotein and glycolipid antigens found on the surface of an erythrocyte are called agglutinogens, and a person with agglutinins that react with type A and blood type B has type O blood. 6.During embryonic development, ninety-nine percent of the cardiac fibers are specialized for the function called contraction, whereas the remainder is specialized for inherent and rhythmical electrical activity (Autorhythmic) . 7.The action potential delay at the AV node ensures that atrial excitation and contraction are complete before ventricular excitation and contraction commence. 8.The end systolic volume (ESV) is the volume of blood in the ventricle after ejection has been completed. An increase of this volume occurs when the stroke volume is decreased. 9.The three cations, K+, Ca2+, and Na+ have an important effect of heart function. Increased blood levels of Na+ blocks Ca2+ inflow and results in a decrease in the force of contraction, while an excess of K+ blocks the generation of action potentials. 10. An increase in parasympathetic activity stimulation has the following effect on stroke volume: decreases stroke volume; an increase in parasympathetic activity weakens atrial contractility.