Date | November 2016 | Marks available | 8 | Reference code | 16N.2.HL.TZ0.6 |
Level | Higher level | Paper | Paper 2 | Time zone | TZ0 / no time zone |
Command term | Explain | Question number | 6 | Adapted from | N/A |
Question
The human circulatory system is structured to serve the organs and tissues of the body efficiently.
Explain how circulation of the blood to the lungs and to other systems is separated in humans and what the advantages of this separation are.
Distinguish between the composition of the blood of the renal artery and the blood of the renal vein.
Markscheme
a. double circulation / pulmonary and systemic circulations
b. heart is a double pump / heart has separate pumps for lungs and other systems / left and right sides of heart are separate / no hole in heart (after birth)
c. deoxygenated blood pumped to the lungs and oxygenated to other organs/tissues/whole body (apart from lungs)
d. each side of the heart has an atrium and a ventricle
e. left ventricle/side pumps blood to the systems/tissues and right ventricle/side pumps blood to the lungs
f. left atrium receives blood from the lungs and right atrium receives blood from systems/tissues
g. left ventricle pumps blood via the aorta and right ventricle pumps blood via the pulmonary artery
h. left atrium receives blood via the pulmonary vein and right atrium receives blood via the vena cava
i. lungs require lower pressure blood / high pressure blood would damage lungs
j. high pressure required to pump blood to all systems/tissues apart from lungs
k. pressure of blood returning from lungs not high enough to continue to tissues / blood has to be pumped again after returning from lungs
l. oxygenated blood and deoxygenated blood kept separate / all tissues receive blood with high oxygen content/saturation
Points may be earned using an annotated diagram.
a. less urea/excretory waste products/creatinine in renal vein
b. less oxygen in the renal vein
c. more carbon dioxide in renal vein
d. less glucose in renal vein
e. concentration of sodium ions/chloride ions/pH at normal level in the renal vein whereas it is variable in renal artery
f. solute concentration/osmolarity/water balance at normal level in the renal vein whereas it is variable in renal artery
Allow answers in a table format. For all these mark points accept the converse as long as it is clear whether the artery or vein has the higher amount.
Answers relating to volume and pressure are not relevant to the question.