Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 135

1 Which of the following layers of the heart is composed predominantly of branched cardiac muscle fibres?a) The endocardiumb) The epicardiumc) The myocardiumd) The visceral pericardium

2 The bicuspid (mitral valve) is locateda) Between the left atrium and left ventricleb) Between the right atrium and right ventriclec) At the origin of the pulmonary arteriesd) At the origin of the aorta

3 During which phase of the cardiac cycle does 70 per cent of the atrial blood volume pass into the ventricles?a) Isovolumetric contractionb) Passive ventricular fillingc) Ejectiond) Atrial systole

4 Which of the following resting heart rates would be referred to as tachycardia?a) 90 bpmb) 45 bpmc) 112 bpmd) 75 bpm

5 Which of the following areas of the cardiac conductive system acts as the heart’s natural pacemaker?a) The atrioventricular bundle (bundle of His)b) The Purkinje fibresc) The atrioventricular node (AVN)d) The sinoatrial node (SAN)

6 Angina pectoris is usually associated with occlusion ofa) The aortab) The coronary arteriesc) The carotid arteriesd) The pulmonary arteries

7 Which of the following blood vessels do not carry oxygenated blood?a) The pulmonary veinsb) The coronary arteriesc) The aortad) The pulmonary arteries

8 The major baroreceptors that continually measure arterial blood pressure are located ina) The vena cavaeb) The pulmonary arteriesc) The jugular veinsd) The aortic arch and carotid sinuses

9 Antidiuretic hormone (ADH), which is also known as vasopressin, is released whena) Blood pressure decreasesb) The blood is diluted by drinking too much waterc) The kidneys need to eliminate calcium (Ca)d) Blood pressure increases

10 Which of the following statements relating to the renin angiotensin aldosterone system (RAAS) is true?a) The system is activated when blood pressure is highb) Angiotensinogen is produced by the kidneyc) Angiotensin-II is a powerful vasoconstrictord) Renin is produced by the liver

Chapter summary

The cardiovascular system, consisting of the heart and blood vessels, functions as the major transport system. Blood acts as the transport medium and is continually circulated throughout the body in the blood vessels. Arteries are muscular, thick-walled vessels that usually carry oxygenated blood under high pressure away from the heart, while veins are thin-walled blood vessels equipped with valves that usually carry deoxygenated blood under low pressure towards the heart.

Capillaries are the smallest blood vessels and found in complex networks termed capillary beds which permeate the tissues of the body and function to distribute blood. The right-hand side of the heart pumps deoxygenated blood to the lungs via the pulmonary circuit, while the left-hand side pumps oxygenated blood to all other areas (organ systems) via the systemic circuit. The heart is anchored in a relatively central position within the thorax (retrosternal) and protected by a compound membrane termed the pericardium. To function as an efficient pump, the chambers of the heart contract and relax in a five-phase sequence termed the cardiac cycle.

The events of the cardiac cycle are precisely timed and coordinated by the cardiac conductive system. The electrical activity of this system can be recorded on an electrocardiogram. Blood pressure (BP) is a product of cardiac output (CO) and the peripheral resistance (PR) afforded by the blood vessels (BP = CO × PR). Ideally, blood pressure is maintained at around 120/80 mmHg by a combination of neural and hormonal mechanisms.