The heart is the only organ containing cardiac muscle
Medulla Oblongata
working on my circadian rhythmicity
Kenneth Clarke Fisher has written: 'Heart rhythmicity of embryo fish. 1. The effect of temperature on te hear rate of trout embryos'
medulla oblongata, in the brain stem.
Christopher John McCabe has written: 'Genetic aspects of rhythmicity in Drosophila melanogaster'
a pacemaker that initiated each contraction of a heart beat "Autorhythmic cells: cardiac or smooth muscle fibers that are self-excitable; act as the heart's pacemaker and conduct the pacing impulse through the conduction system of the heart; self-excitable neurons in central nervous system,as in the inspiratory area of the brain stem." -Principles of Anotomy and physiology, TORTORA, DERRICKSON, 11th edition, Wiley & sons, Inc. (c) 2006 by bio. Sci. textbooks, Inc. and Bryan Derrickson
- rhythmicity : capability of rhythmic self-excitation therefore no need for external control -conductivity: conduction of action potential along specialised muscle cells. -excitability: ability of muscle fibers to get exited . -contractility; ability of cardiac muscle to contract . It also has a long refractory period meaning it cant tetanus
Autorhythmicity is the tendency for the sinoatrial node of the heart to have a low threshold for depolarization leading to the heart contracting on a regular basis, i.e. in a regular rhythm, without external stimulus from the nervous system.
The rhythmicity of breathing is primarily controlled by the brainstem, particularly the medulla oblongata and pons. Neurons in these areas generate rhythmic patterns of activity that regulate the contraction of respiratory muscles. Additionally, sensory input from chemoreceptors and mechanoreceptors helps modulate the rhythm based on the body’s metabolic needs, such as changes in carbon dioxide and oxygen levels. This complex interplay ensures that breathing remains automatic yet adaptable to various physiological demands.
there is a specific group of cells found in the medula (part of the brain stem) which regulate the rhythm of breathing, hence the name (of this cellular formation) the Medulary Rhythmicity Center.
The heart is an involuntary muscle.Involuntary muscles are smooth muscles that are not directly controllable at will. Voluntary muscles are controllable like those found in your arms, legs, hands, etc.
These cells look just like regular heart cells. But some create rhythmical impulses and they directly control the heart rate. The sinoatrial node (SA node) is a group of these cells positioned on the wall of the right atrium. Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the primary pacemaker. Further down into the heart at a junction between the artium and ventricles is the AV node which is called the secondary pacemaker. The last part of electrical conducting system of the heart is the Bundle of His which include left and right branches of this bundle, and the Purkinje fibers. These will also produce a spontaneous action potential at a rate of 30-40 beats per minute, if the SA and AV node both do not function.