Lesson 6 - Controlling the heart Flashcards
(12 cards)
meaning intrinsic rhythmicity
the intrinsic rhythm of contraction and relaxation of the cardiac muscle making up the heart
meaning sinoatrial node (SAN)
a group of cells in the right atrium. It is the area of the heart with the fastest intrinsic rhythm and acts as the heart’s own natural pacemaker. The sinoatrial node sets up a wave of electrical excitation that causes the atria to start contracting, which initiates the heartbeat
meaning annulus fibrosus
consists of non-conducting tissue that provides support for the heart and spreads between the atria and the ventricles, preventing the wave of excitation that spreads through the atria from passing directly into the ventricles
meaning atrioventricular node (AVN)
a group of cells stimulated by the wave of excitation from the SAN and atria. It imposes a delay before transmitting the impulse to the bundle of His
meaning bundle of His
a group of conducting fibres in the septum of the heart. They ensure that the atria has stopped contracting before the ventricle starts. The bundle of His splits into 2 branches and carries the wave of excitation on into the Purkyne tissue
meaning purkyne tissue
made up of conducting fibres that penetrate down through the septum of the heart, spreading between and around the ventricles. As the wave of excitation travels through the tissue, it sets of the contraction of the ventricles, starting at the apex (bottom) and so squeezes blood out of the heart
meaning electrocardiogram (ECG)
used to investigate the rhythms of the heart by producing a record of the electrical activity of the heart
what are 3 factors which affect heart rate
- age
- level of physical activity
- stress
how does physical activity affect heart rate
during physical activity, the muscles need more oxygen, so the heart must beat faster to supply oxygenated, glucose-carrying blood to the tissues and remove the increased waste products
in simple words, how is the cardiac cycle controlled
the speed at which the wave of depolarisation spreads through the heart, with the hesitation of the AVN stimulates the bundle of His, making sure that the atria has stopped contracting before the ventricles starts. It is these changes in the electrical excitation of the heart that causes the repeating of the cardiac cycle
how is an EGC taken
- Your skin is wiped with alcohol to remove any grease or sweat so the electrodes make good contact. Sometimes, a special gel is applied to ensure the electrodes conduct electricity as effective as possible.
- 12 electrodes and leads are attached to your body
- as the recordings are made, information is fed back from each of the electrodes, giving 12 views of the heart
what is an EGC used for
- to indicate different heart conditions
- ## to monitor patients with heart disease
