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Heart Concept map, The heart:
An extremely sophisticated muscle,…
Heart Concept map
The Cardiovascular system:
- Its main purpose is to circulate gases, nutrients, wastes, and other substances to and from the cells of the body (20.3)
Heart:
- Located within the thoracic cavity, medially between the lungs in the space known as the mediastinum (19.1)
- It pumps blood throughout the body in a network of blood vessels (19.1)
Blood Vessels:
- How are blood is carried throughout the body (20.1)
- Arteries carry blood away from the heart, branching out into smaller vessels (20.1)
- Arterioles branch into capillaries, nutrients and waste are exchanged here, they will then combine with other vessels that exit capillaries to form venules, a larger blood vessel that returns blood to the heart. (20.1)
The heart:
- An extremely sophisticated muscle, constantly pumping blood through the body (Ch. 19 intro)
Pericardium:
- The membrane which separates the heart from other mediastinal structures, consisting of two layers (Key terms)
Superficial:
- The superficial layer is the Fibrous Pericardium, made of tough, dense connective tissue (19.1)
- Protects the heart while also maintaining its position in the thorax (19.1)
Deep:
- The deep layer is a Serous membrane, it is more delicate and consist of two layers: Parietal layer, fused with the superficial layer, and inner visceral pericardium / epicardium (19.1)
- Between the pericardium and epicardium is lubricating serous fluid. This Helps reduce friction as the heart contracts (19.1)
Chambers:
- The heart consist of four chambers, the left and right side have one atrium and ventricle each(19.1)
- The atria act as a receiving chamber, contracting to push blood into the lower chambers. (19.1)
- The ventricles are the primary pumping chambers, propelling blood to the lungs or to the rest of the body (19.1)
Atria:
- receiving chamber, contracts to push blood into the lower chambers (19.1)
- The right atrium receives blood from the systemic circuit that flows into the right ventricle (Key terms
- The Left atrium receives blood from the pulmonary circuit that flows into the left ventricle
Ventricles:
- serve as the primary pumping chambers of the heart, propelling blood into the lungs or the rest of the body (19.1)
- The left ventricle is the major pumping chamber that ejects blood into the systemic circuit via the aorta and receives blood from the left atrium (Key terms)
- The right ventricle is also a major pumping chamber on that ejects blood into the pulmonary circuit via pulmonary trunk and receives blood from the right atrium (Key terms)
Sides:
- The heart can be broken up into two sides, each having one atrium and one ventricle (19.1)
Left (Systemic Circuit):
- Transports oxygenated Blood to all of the tissues of the body and returns deoxygenated blood and CO2 to the heart to be sent back to the pulmonary circulation (right side of the heart) (19.1)
Right (pulmonary Circuit):
- Blood flow to and from the lungs (Key terms)
- Picks up oxygen and delivers Co2 for exhalation (19.1)
- provides gas exchange through the arteries, veins, and capillaries that run from the heart, through the body and back to the lungs (key terms)
The Heart (continued)
Two systems regulating Heart Activity:
- auto rhythmicity - the ability to initiate an electrical potential at a fixed rate that spread rapidly from cell to cell to trigger the contractile mechanism (19.2)
- Despite cardiac muscle having auto rhythmicity, heart rate and other activities are regulated via the nodal system and ANS
Autonomic Nervous system:
- The system responsible for homeostatic reflexes, coordinating control of cardiac and smooth muscle, as well as glandular tissue (Key terms)
- Both sympathetic and parasympathetic stimulations flow through nerve fibers near the base of the heart; the cardiac plexus. (19.4)
- Sympathetic stimulation releases NE (norepinephrine); this can increase heart rate and force of contraction, temporarily constricting blood vessels to organs not essential for flight-or-fight response. It will also redirect blood to flow to the liver, muscles, and heart. (19.4, 20.4)
- Parasympathetic stimulation releases ACh (acetylcholine) causes the heart rate to decrease(19.4)
Intrinsic Nodal System:
- The conduction system of the heart
- Embryonic heart cells can generate an electric impulse followed by a contraction. When two cells join, the cell with the higher inherent rate sets the place, spreading the impulse from faster to slower cells, triggering a contraction. The fastest cell assumes control. (19.2)
- This system is composed/includes the sinoatrial node, atrioventricular node, atrioventricular Bundle branches, and the Purkinje Cells
The heart (continued)
Heart Wall:
The heart wall is made of 3 layers which are unequal in thickness. From superficial to deep, it is the outer Epicardium, a thick Myocardium, and the inner lining Endocardium (19.1)
Myocardium:
- The thickest layer of the 3, built upon a framework of collagenous fiber, plus the blood vessels that supply the myocardium and the nerve fibers that help regulate the heart (19.1)
- The contraction of this layer is what helps pump blood through the heart and into major arteries (19.1)
Endocardium:
- joined to the myocardium with a thin layer of connective tissue (19.1)
- it lines the chambers where the blood circulates and covers the heart valves (19.1)
- composed of endothelium reinforced with a thin layer of connective tissue that binds to the myocardium (Key terms)
Epicardium:
- a macroscopic layer compared to other visceral serous membranes (19.1)
- It consist of simple squamous epithelium called mesothelium, reinforced with loose, irregular, or areolar connective tissue that attaches to the pericardium (19.1)
- This mesothelium also secretes a lubricating serous fluid which fills the pericardial cavity to reduce friction when the heart contracts (19.1)
Ventricle Filling & atrial contraction:
- At the beginning of the cycle, both ventricles and atria are relaxed
- Blood flows into the right atrium from the superior and inferior venae cavae and the coronary sinus. Blood flows into the left atrium from the 4 pulmonary veins. 2 atrioventricular valves, tricuspid and mitral valves, open up so blood flows into the atria and into the ventricles
- When the atria contract, depolarization follows. As the atria muscles contract from the superior portion of the atria toward the atrioventricular septum, pressure rises within the atria and blood is pumped into the ventricles. (19.3)
This is also referred to the "atrial Kick"
Ventricular Systole:
- follows the depolarization of the ventricles. (19.3)
- when the muscles in the ventricle contract, it's not high enough of blood pressure to open the semilunar valves. However, blood pressure quickly rises above that of the atria that are now relaxed and in diastole. The increase in pressure causes blood to flow back to the atria, closing both tricuspid and mitral valves. This phase is also called Isovolumetric contraction (19.3)
- The second phase is ventricular ejection. The contraction of the ventricular muscle has raises the pressure in the ventricle greater than the pulmonary trunk and aorta. Blood pumps through the heart and pushes the pulmonary and aortic (semilunar) valves open. (19.3)
Isovolumetric Relaxation:
- Initial phase of the ventricular diastole when pressure in the ventricles drop below pressure in the two major arteries, pulmonary trunk, and aorta. Blood attempts to flow back into the ventricles, closing the semilunar valves to prevent back flow (key terms)
- in the second phase the ventricular muscle relaxes and pressure on the blood within the ventricles drop further and will drop below the pressure in the atria. When this occurs, blood flows back from the major veins into the relaxed atria and into the ventricles. Both chambers become diastole, atrioventricular valves open, and semilunar valves close. (19.3)
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The Cardiac Cycle:
- The period of time between the onset atrial constriction (atrial systole) and ventricular relaxation (ventricular diastole) (key terms)
- The period of contraction that the heart undergoes while it pumps blood into circulation is called systole (19.3)
- The period of relaxation that the heart undergoes as the chambers fill with blood is called diastole. (19.3)
Both atria and ventricles undergo both periods (19.3)