Hepatic circulations in animals The hepatic blood supply from the hepatic artery and portal vein is governed by hepatic arterial vascular resistance, the arterial tone in the vascular beds of the gastrointestinal tract, pancreas, and the spleen and the intrahepatic portal venous vascular resistance. The total hepatic blood flow in humans, cats and dogs contributes […]

Blood flow to rumen and spleen in animals Rumen blood flow Feeding and the products of rumen digestion, carbon dioxide and volatile fatty acids, increases rumen blood flow. Splenic Circulation In certain mammals (dog, cat, horse, guinea pig) the spleen serves as a reservoir of blood. Normally blood is stored in the venous sinuses and

Splanchnic circulation in animals The splanchnic circulation consists of three parts: The mesenteric bed, supplying the gastrointestinal tract; The splenic bed and The hepatic bed. A unique feature of this circulatory system is that the combined outflow from the mesenteric and splenic constitutes the major portion of the inflow of the hepatic through the portal

Skeletal muscle circulation in animals Under normal resting condition, blood flow to the skeletal muscle is 15% and this varies according to the activity of the muscle. Blood flow to the skeletal muscle is controlled by the alpha adrenergic sympathetic system tone on the blood vessels. The neurotransmitter substance involved is the norephinephrine which stimulates

Cutaneous circulation in animals The skin is supplied by a dense network of cutaneous arterioles under the dermis layer. These arterioles inturn divide into metarterioles which inturn give rise to capillary loops. These capillary loops provide a greater surface area for heat exchange mechanism. The venules form an extensive sub papillary venous plexus. Arteriovenous anastomoses

Cerebral circulation in animals Cerebral circulation constituents about 14% of the cardiac output. The arteries that supply the brain are the anterior, middle and posterior arteries of both sides through a common arterial pathway, the circle of Willis. In most of the species this circle is supplied by the internal carotid arteries and vertebral arteries, whereas

Shock in animals Shock is an acute circulatory state in which the cardiac output is insufficient to maintain adequate blood flow to the tissues. Any condition causes a sudden decrease in circulating blood volume or increase in volume of the vascular system reduces the mean circulatory pressure results in shock. Causes of shock Shock may

Adjustment of circulation during exercise The response of circulatory system to exercise is an integration of nervous system, endocrine, musculoskeletal and cardiovascular system. During exercise the demands on the circulatory system greatly varies. In the most of the human beings there is an increase in oxygen consumption to five fold within in a few minutes

Control of veins in animals On sympathetic stimulation adrenaline causes venous constriction but has no influence on peripheral resistance to increase venous return to the heart to maintain normal cardiac output and BP. In dog and cat, the sympathetic vasoconstrictor fibres (spinal nerves from lumbar 2-4) control the vasomotion in the veins of the hind

Control of capillaries Local control of blood flow – Capillaries regulate the local blood supply to the tissues according to the need of the tissues. Micro circulation Metabolic control of blood flow to an organ is the most important local control mechanism. Increased blood flow in tissues in response to increased metabolic rate is called