Heart Education Awareness Resource and Training through eLearning (HEARTe)


Integration of the heart on body systems

The activity of the heart and cardiovascular (CV) system is regulated to ensure adequate blood supply to all tissues and organs throughout the body. There are three main systems involved in the regulation of the CV system: the nervous system, the kidneys and the endocrine system. The rate of the beating heart is normally determined by the pacemaker of the heart i.e. the sino-atrial node. The rate of the pacemaker is modulated by the autonomic nervous system.

Full body picture, with rollovers on each point, a sentence for each and how they interact with the heart.

  • The nervous system
    The autonomic nervous system (ANS) is a complex system which has many influences on the mechanisms affecting the whole body.
    Principally, the ANS is composed of the sympathetic (SNS) and the parasympathetic (PNS) systems which control the heart and cardiovascular system. The SNS is stimulated by nor-adrenaline, released from the sympathetic nerves, and adrenaline, produced in the adrenal glands, which help raise heart rate, increase myocardial automaticity, conduction and contractility.
    The PNS slows the heart rate and slightly reduces the force of muscular contraction, mainly through the action of the vagus nerve. Inhibition of the vagus nerve will increase heart rate and force of contraction, for example, during exercise. Changes in arterial pressure can stimulate pressure receptors, or baroreceptors, in the aortic arch and carotid sinus which, in turn, affect vagal nerve activity and either slow or increase the heart rate to increase or decrease BP (for example on exercising or increased activity).
  • Kidneysmedical flowchart detailing relationship between kidney function, angiotensin, salt, and blood pressure
    The kidneys also affect BP (cardiac output and vascular resistance) by activation of systems, including the renin-angiotensin- aldosterone (RAA) control system in response to a fall in BP.
    The ANS responds by reducing parasympathetic stimulation and increasing sympathetic stimulation. This increases heart rate; increases the force of cardiac contraction; and causes vasoconstriction (increased peripheral resistance ) to obtain an increase in arterial BP. By regulating vascular tone and sodium and water excretion, these mechanisms increase systemic BP, increase venous return to the heart and increase cardiac output.
  • Lungs
    The lungs are responsible for gaseous exchange i.e. the transfer of oxygen form the lungs into the blood stream and removal of carbon-dioxide from the blood stream to the lungs.
    The function of the heart and lungs are interconnected and regulated by a number of mechanisms, including chemoreceptors (chemical-sensing cells). These are found in the cardiovascular system (carotid artery and aorta) and monitor the chemical characteristics of the blood (i.e. oxygen, carbon dioxide and hydrogen levels) to help regulate function of both cardiovascular and respiratory systems. The primary influence of chemoreceptors is on respiration. So, for example, if they sense a decrease in oxygen concentration and an increase in the carbon-dioxide levels the heart rate and breathing rate and depth increase to eliminate the waste products from the blood.

Page last reviewed: 20 May 2020