Control of Heart Rate in Humans

Starter Label heart diagrams

Structure of the heart deoxygenated blood to the lungs oxygenated blood to the body deoxygenated blood from the body oxygenated blood from the lungs

Learning Objective Success Criteria Know how we control heart rate Outline the hormonal and nervous mechanisms involved in the control of heart rate

Cardiac Cycle Using the key words below in pairs write a paragraph to describe the cardiac cycle Pacemaker, Atrio-Ventricular node, myogenic, Sino-Atrial node, Atria, Ventricles, Purkyne Tissue When finished swap with another pair and see if you can improve their work

Think about what happens: when you walk down a quiet road late at night and you’re afraid your being followed Or before an exam.

sympathetic Nervous System Increases the heart rate, to increase oxygen supply to the muscles. Increases the ventilation rate, so that more oxygen can be absorbed in the lungs. Decreases peristalsis in the gut so there is more blood available for the heart and lungs. Other parts of the body also respond to enable increased sensory awareness eg pupils dilate

Parasympathetic Nervous System Relaxing responses - decreases over all physical activity, so it is associated with rest. It decreases heartbeat rate It decreases ventilation rate It increases peristalsis in the gut, so that food can be digested

Nervous Control of Heart Rate Nerves from cardiovascular centre in medulla oblongata (in brain) supply heart Connect to SAN Effect frequency of beats Action potentials sent down the accelerator nerve (sympathetic NS) increase heart rate Action potentials sent down the vagus nerve (parasympathetic NS) decrease heart rate

Hormonal Control of Heart Rate Heart muscle responds to adrenaline in blood

Normal conditions Resting heart rate controlled by SAN Varies from person to person Frequency of 60-80 beats per min This can be controlled by the cardiovascular centre in the medulla oblongata

Factors that affect Heart Rate Movement of limbs detected by stretch receptors in muscles Send impulse to cardiovascular centre Increases heart rate Production of CO2 during exercise Reduces blood pH Detected by chemoreceptors in carotid arteries, aorta and brain

Factors that affect Heart Rate Decrease in CO2 after exercise Reduces activity of accelerator nerve Decrease in heart rate Adrenaline secretion Increases heart rate Blood pressure Monitored by stretch receptors in walls of carotid sinus Blood pressure too high, impulse sent to cardiovascular centre, impulse sent down vagus nerve

Artificial Pacemaker Read a section of information on artificial pacemakers and make notes about its development, forming a timeline

Heart Rate Jan 11 [5]

Heart Rate Jan 11 Markscheme