The human heart pumps blood through the arteries, which connect to smaller arterioles and then smaller capillaries. In this assignment, we will discuss the arterial blood pressure from several aspects, include definition, normal values for blood pressure, the most important factors affecting it, the mechanism involved in arterial blood pressure regulation, and the relevance between the pressure and the eye. Definition of blood pressure, it’s Normal value, and the factors that determine arterial blood pressure under physiologic conditions. Blood pressure refers to the force exerted by the blood against the inner walls of the blood vessels . This pressure produces when the heart contracts during the heartbeat cycle, which forces blood out
The bag is then inflated until the air pressure in the cuff overcomes the arterial pressure and obliterates the arterial lumen. This is confirmed by palpating the radial pulse that disappears when the cuff-pressure is raised above the arterial pressure. The pressure is then raised further by 20 mm Hg and then slowly reduced. When the pressure in the cuff reaches just below the arterial pressure, blood escapes beyond the occlusion in to the peripheral part of the artery and the pulse starts reappearing. This is detected by the appearance of sound heard in the stethoscope and pressure at which the sounds are first heard is the systolic pressure.
As the blood leaves the ventricles, the pressure in the aorta and pulmonary artery surpasses the ventricular pressure. Consequently, the semi lunar valves shut and the chordae tendineae attached to the valves prevent them from inverting, thus preventing back-flow. The shutting of these valves can be heard as the second heart beat (S2). At this point, the ventricles are in isovolumic ventricular relaxation as both sets of AV valves and semilunar valves are closed. Both the T wave and P wave are similarly shaped but they represent different phases of the cardiac cycle, repolarisation and depolarisation
Therefore, platelets undergo degranulation the exocytosis of their cytoplasmic granules and release of factors that promote hemostasis. Aggregation is occurs when serotonin (vasoconstrictor), ADP (attracts more platelets and stimulates their degranulation), and thromboxane A2 (stimulates degranulation and vasoconstriction) are released. Thus it can quickly seal a small break in blood vessel. Coagulation is the last process of the hemostasis. It has three ways; intrinsic, extrinsic and common pathways.
When the right atrium contracts, it pushes the blood cells through a valve which leads to another chamber in the heart. This valve is called the tricuspid valve. It is named this because it has three leaflets. It is a one way valve, which normally only allowing blood to travel from the right atrium to the right ventricle. There are certain conditions where the flow can reverse.
An electrocardiogram is a reading of the electrical activity of the heart made from electrodes placed on the surface of the skin (2010, 01). Electrocardiogram reading shows the sum of the electrical potential generated by the cells in the heart at any moment (2010, 01). The points on an electrocardiogram will show depolarization or repolarization of a portion of the heart. Depolarization is the signal for contraction (VanPutte, 2011). Repolarization is the recharging of the heart after each heartbeat (VanPutte, 2011).
Sometimes other signs and symptoms precede sudden cardiac arrest. These may include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting. But sudden cardiac arrest often occurs with no warning. Unlike other muscles in the body, which rely on nerve connections to receive the electrical stimulation they need to function, the heart has its own electrical stimulator — a specialized group of cells called the sinus node located in the upper right chamber (right atrium) of the heart. The sinus node generates electrical impulses that
UNIVERSITY OF SHARJAH COLLEGE OF MEDICINE MUSCLOSKELETAL UNIT PHYSIOLOGY PRACTICAL HANDOUT PREPARED BY: DR SUNDUS AL-OMAR ACADEMIC YEAR (2011-2012) Nerve Conduction Velocity Theory background The nerve impulse is a wave of depolarization immediately followed by a wave of repolarization, collectively called an action potential, occurring on the plasma membrane of a nerve fiber. Changes in ion conductance across the nerve fiber membrane are responsible for the initiation and propagation of the action potential. Experimentally, these changes can be the result of electrical current applied through electrodes. Once initiated, an action potential is usually propagated without decrement in amplitude or velocity along the plasma membrane of a nerve fiber. In the peripheral nervous system, nerve fibers of various diameters and functions (motor and sensory) are bundled together by connective tissue to form nerves.
Among other things, the right atrium is the attachment point for the sinoatrial node. The sinoatrial node or SA node is the primary pacemaker site for the heart. It is innervated by the parasympathetic nervous system from the vagus nerve. The parasympathetic nervous system controls the vegetative functions of the body. As it pertains to the parasympathetic nervous system, the SA node provides the control of the heart’s rate in distress through the release of acetylcholine.
2. . The P wave of a normal electrocardiogram indicates: F. A. Atrial depolarization G. B. Ventricular depolarization H. C. Atrial repolarization I. D. Ventricular repolarization J. E. Tachycardia 3. . Blood in the pulmonary veins enters: K. A. Right atrium L. B. Left atrium M. C. Right ventricle N. D. Left ventricle O. E. Lung 4. .