Introduction
The cardiovascular system provides appropriate organ and tissue perfusion at rest and at times of stress by regulation of blood pressure (BP). BP can be expressed as the product of cardiac output (CO) and peripheral resistance. The arterial pressure level at any given time reflects the composite activities of the heart and the peripheral circulation.(Jones, 2004). Nervous system, hormonal and Kidney factors control blood pressure.
1. Nervous System
1.1 CO – Cardiac output
CO may be increased or decreased by autonomic nervous system activity that travels between reflex centers in the medulla oblongata and the SA node of the heart. Control of CO is governed by two kinds of mechanisms: primary mechanisms, which operate quickly for acute …show more content…
Sympathetic fibers extend between the medulla and the heart joining the SA and AV nodes. Some sympathetic fibers terminate in the myocardium of the ventricles. The sympathetic nerves transmit their message to the muscle cells of the heart and arteries by the release of norepinephrine (NE), which increases both the heart rate and stroke volume. Sympathetic stimulation increases BP. (Winberg, 2014).
1.1.2 Parasympathetic nervous system - Parasympathetic fibers
Heart activity may be altered by the cardiac center in the medulla oblongata of the brain. This reflex center is connected to the heart by way of autonomic fibers, specifically; parasympathetic fibers extend from the medulla by way of the vagus nerve (CN X) to the heart where they branch to the SA and AV nodes. The effect of parasympathetic impulses reaching the heart is to slow the heart rate by the release of acetylcholine (Ach). Parasympathetic stimulation reduces BP (Winberg, 2014).
1.2. Peripheral
The cardiovascular system provides appropriate organ and tissue perfusion at rest and at times of stress by regulation of blood pressure (BP). BP can be expressed as the product of cardiac output (CO) and peripheral resistance. The arterial pressure level at any given time reflects the composite activities of the heart and the peripheral circulation.(Jones, 2004). Nervous system, hormonal and Kidney factors control blood pressure.
1. Nervous System
1.1 CO – Cardiac output
CO may be increased or decreased by autonomic nervous system activity that travels between reflex centers in the medulla oblongata and the SA node of the heart. Control of CO is governed by two kinds of mechanisms: primary mechanisms, which operate quickly for acute …show more content…
Sympathetic fibers extend between the medulla and the heart joining the SA and AV nodes. Some sympathetic fibers terminate in the myocardium of the ventricles. The sympathetic nerves transmit their message to the muscle cells of the heart and arteries by the release of norepinephrine (NE), which increases both the heart rate and stroke volume. Sympathetic stimulation increases BP. (Winberg, 2014).
1.1.2 Parasympathetic nervous system - Parasympathetic fibers
Heart activity may be altered by the cardiac center in the medulla oblongata of the brain. This reflex center is connected to the heart by way of autonomic fibers, specifically; parasympathetic fibers extend from the medulla by way of the vagus nerve (CN X) to the heart where they branch to the SA and AV nodes. The effect of parasympathetic impulses reaching the heart is to slow the heart rate by the release of acetylcholine (Ach). Parasympathetic stimulation reduces BP (Winberg, 2014).
1.2. Peripheral