Question
Mammals have closed, double circulatory systems.
(a) Explain what are meant by the terms closed and double as applied to mammalian
circulatory systems.
closed ………………………………………………………………………………………………………………
double ………………………………………………………………………………………………………………
Fig. 5.1 shows a longitudinal section through a mammalian heart.
(b) Use label lines and the letters P, Q, R and S to label the following on Fig. 5.1:
P the right atrium
Q a semilunar valve
R a blood vessel that carries deoxygenated blood
S the position of Purkyne tissue
Catheters are small tubes that are inserted into blood vessels. A catheter was inserted into
an artery in the arm and then moved into the aorta and then into the left ventricle during a
diagnostic investigation. The catheter contained a device to measure the blood pressure in
the aorta and in the left ventricle. The results are shown in Fig. 5.2.
(c) (i) Calculate the heart rate during the period of the investigation.
Show your working.
answer …………………………………………..
(ii) Describe and explain the differences in pressure as the catheter moves from the aorta into the left ventricle.
Fig. 5.3 is an X-ray showing narrowing in the blood vessels supplying muscles in the heart.
A catheter is used to insert a dye into the blood vessels so that they appear clearly in the
X-ray. The arrows indicate where there is narrowing of the blood vessels.
(d) (i) Name the blood vessels shown in Fig. 5.3.
(ii) State the likely effect of narrowing of these blood vessels.
(e) Suggest ways in which the condition shown in Fig. 5.3 may be treated.
Answer/Explanation
Answer:
(a) closed blood travels, inside blood vessels / AW ;
double blood travels through the heart twice during one, complete circuit / circulation
of the body ; AW
A pulmonary and systemic, systems / circuits
(b) P to right atrium ;
Q to (semilunar) pulmonary or aortic valve ;
R to, vena cava / pulmonary artery ;
S to, septum / wall(s) of ventricles ;
(c) (i) 75 (beats per minute) ;;
if incorrect answer or no answer allow one mark for extraction from Fig. 5.2 or for correct
working
e.g.10 beats in 8 seconds
10/8 × 60
(ii) max 3 if only description or only explanation given
lowest pressure in aorta, is 10.8 kPa / varies between 10.8-11.2 kPa v in left ventricle
is 0 KPa ;
difference between highest and lowest is greater in the ventricle / AW ;
4.8 – 5.2 kPa for aorta, 16.0 kPa in left ventricle ;
reference pressure differences (in left ventricle) as a direct result of ventricular systole
and diastole ;
semilunar / aortic, valve prevents backflow from aorta into ventricle ;
(so) no / little, blood in ventricle, when fully contracted / AW ;
elastic recoil of artery maintains (diastolic) blood pressure ;
AVP ;
(d) (i) coronary arteries ;
(ii) insufficient, glucose / oxygen (to, cardiac / heart, muscle) ;
angina ;
heart attack / myocardial infarction / cardiac arrest ;
description of anaerobic conditions in muscle ;
(e) coronary (artery) by-pass (graft) operation ;
R by-pass unless qualified
A described
insertion of a (coronary) stent ; A described
heart transplant ;
angioplasty ; A described
AVP ; e.g. calcium-channel blockers / named
further detail of treatments e.g. anticoagulants after angioplasty