Control of arterioles in animals Control of arterioles in animals involves Neural regulation and Hormonal regulation Neural regulation by vasomotor centers It is located bilaterally in the medullary reticular formation and lower pons and includes the Vasoconstrictor and Vasodilator centers. This centre receives sensory signals through vagus and glossopharyngeal nerves. The output signals from these centers regulate […]

Vasomotor mechanism and reflexes Vasomotor mechanism and reflexes deals with the maintenance of the diameter of the blood vessels (arteries and arterioles) to maintain BP, thus regulates the blood flow to various organs or tissues according to their demand. Functions of Vasomotor mechanism Regulates blood flow to different organs according to their demand. i.e. shifting of blood

Nervous Regulation of arterial pressure in animals Baroreceptor reflex Arterial blood pressure is monitored by pressure sensitive nerve endings known as baroreceptors; Carotid sinus and aortic body located in the carotid bodies and aortic arch are sensitive to stretch of the arterial wall. The frequency of impulses generated from baroreceptors is proportional the BP. They send afferent

Regulation of arterial pressure in animals Two mechanisms regulate the arterial pressure. Rapidly acting short term regulatory mechanism operates through nerves or hormones and Long term control of arterial pressure. When the BP undergoes change, after few hours to few days the nerves loose their power to control pressure because receptors adapt. Long-term mechanisms come

Factors influencing production and maintenance of blood pressure Heart beat During systole, the arterial pressure increases. The rate at which blood enters the arterial system exceeds the rate at which it drains through arterioles and capillaries, increasing the pressure. During diastole, the BP decreases since blood passes out of arteries into capillaries. When other three

Determination of arterial blood pressure Arterial blood pressure helps in diagnosing the defects of heart and circulatory system. It can be measured by two means- The direct and The indirect (clinical) methods. Direct method Experimentally the carotid artery can be connected to any of the following devices such as, the mercury manometer, membrane manometer or the

Mean circulatory filling pressure Mean circulatory filling pressure eventual pressure in the static circulatory system when there is no pressure difference between the aorta and the vena cava and the pressure throughout the circulatory system which is called mean circulatory filling pressure, and it is  is 7 mm Hg. This pressure is caused by the

Blood Pressure in animals Blood Pressure in animals is the pressure exerted by the circulating blood against any unit area of the blood vessel wall. Stephen Hales (1730) demonstrated the existence of pressure in the blood vessels. Average pressure in the aorta is 98 mm Hg and the mean pressure in veins is 3 mm

Blood Flow and Velocity in animals Blood Flow The blood flows at a steady rate through a long smooth vessel with each layer of blood remaining in the same distance from the wall i.e it flows in streamlines. The central portion of the blood stays in the centre of the vessel. This type of flow

Hemodynamics and Distribution of blood in the systemic circulation Physiology of circulation (Hemodynamics) Circulation is a continuous circuit through which the same amount of blood flow through each subdivision of circulatory system is maintained by the heart. In a resting animal about 25% of the blood volume is in the central circulation (pulmonary and coronary circulation) and