Circulatory system consists of three independent parts, closely related topographically and functionally: the circulatory system with a central body - the heart, the lymphatic system, organs hemodialysis and lymphopoiesis.
Circulatory system consists of the heart and the system of blood vessels, which are divided into arteries (blood vessels that carry blood from the heart), veins (blood vessels that carry blood to the heart) and microvasculature.
Heart
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| Heart, cardiovascular system of animals |
Heart (cor, kardia) - the central body of blood and lymph, located in the chest cavity from III to VI-VII ribs inside okoloserdechnoy bag (pericardium). Heart is from 0.4 to 1% of body weight. The wall of the heart consists of three layers: the inner (endocardial), middle (infarction) and outer (epicardial). The shape of the heart is a hollow cone-shaped formation, which distinguish top (downward and back) and the base (directed forward and upward). Heart of a four mammals. At the core are two atria (right and left), and most of the heart ventricle form two (left and right), separated by interventricular septum. The muscular layer of the heart (myocardium) in the atria has two layers of striated muscle, and in the ventricles - five layers. Muscles are attached to a special fibrous skeleton of the heart, from four fibrous rings, two of which are located between the atria and ventricles, and two - at the mouth of arterial vessels. The heart has a special valve apparatus which facilitates unidirectional blood flow. This unit has four valves: two stulkovyh - between the atria and ventricles (right tricuspid, left bicuspid or mitral) and two pockets (crescent) The mouth of blood vessels.
Cardiac muscle is characterized by four features:
1-avtomatyya - the ability to contract rhythmically influenced by impulses arising in the very heart muscle, and possible special thanks to the neuromuscular system, which consists of sinoatrial, atrioventricular node and bundle branch block;
2-excitability - impulse excitation of the stimulus;
3-conductivity - spreading the excitement of sinoatrial node around the heart;
4-contractility - the ability to meet the reduction only to single pulse excitation.
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| cardiovascular system of animals |
Activity of the heart is cyclical. In isolated cardiac cycle during contraction (systole), representing 40% of the duration of the cardiac cycle, and during relaxation (diastole) - 60% of the duration of the cardiac cycle.Minute volume flow, the amount of blood ejected ventricle of the heart (right or left) in 1 min (20-30 l of a horse, cattle up to 35 l in small ruminants to 4 liters in dogs to 1 5 l).
Systolic volume flow, the amount of blood ejected by the ventricle of the heart per systole (calculated as a private in the distribution of minute volume on the number of cuts in 1 min). This rate in horses is 850 ml in cattle - 580 ml, small livestock - 55 ml in dogs - 14-25 ml.
Regulation of the heart is provided by neural and hormonal mechanisms. Neural mechanisms of regulation related to the activity of the autonomic nervous system and the presence of some vessels reflex zones (accumulation of chemo-and pressosensornyh receptors).Hormonal mechanisms regulating hormones made by the adrenal medulla and the thyroid gland, and potassium ions (urezhayut and weaken the heart reduction), calcium (stimulates cardiac contraction) and other chemicals.
Blood vessels
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| Blood vessels, cardiovascular system of animals |
Blood vessels are a system of hollow tubes, which are grouped in two circulation - large and small. Vessel wall consists of three layers: the inner (tunica intima), middle (tunica media) and outer (tunica adventicia). In arterial vessels are well developed middle layer, which contains muscle and elastic components. The venous system is two to three times more volume arterial. The biggest development in venous vessels is the outer shell. Small (functional) circulation begins in the right ventricle of the heart common trunk of the pulmonary artery, which is divided into lung parenchyma network of capillaries that pass in the pulmonary veins, which carry blood to the left atrium. Large (systemic) circulation starting from the left ventricle and is composed of the following vessels: aorta, major arteries, capillaries, main veins that form two venous pool (cranial and caudal hollow veins) that carry blood to the right atrium. Aorta begins arc, which departs from the right brachiocephalic trunk that carries blood to the head, neck and right half of the right thoracic limb. Doug continues caudally in the thoracic, abdominal, and middle sacral median tail artery.
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| venous, cardiovascular system of animals |
Aorta at its very commencement of the coronary arteries supplying the heart. Chairman krovosnabzhaetsya two common carotid artery (arteria carotis communis), each of which is divided into the external carotid artery with numerous branches to the head and of the internal carotid artery for blood supply to the brain. The neck is blood on the branches of the subclavian arteries (right and left), which depart from the aortic arch (right brachiocephalic trunk is an extension). Subclavian arteries going to the extremities as underarm, shoulder and median. From the thoracic and abdominal aorta away parietal artery (supplies the wall cavity) and visceral (supplies the internal organs). In thoracic visceral artery depart within the esophageal-bronchial trunk. In abdominal visceral branches is fraught artery (supplies the stomach, spleen, liver, duodenum), cranial mesenteric artery (supplies the thin section and part of the large intestine), caudal mesenteric artery (supplies the descending portion of the colon and rectum), kidney and adrenal arteries and arteries to the gonads (ovarian in females, males Semennikova). Then abdominal artery divided into external iliac (supplies the pelvic limb) and internal iliac (supplies the pelvic cavity) artery. The external iliac artery should be on pelvic limb (on the thigh is called the femur), then goes into the popliteal, at the lower leg in front bolshebertsovuyu which the foot becomes dorsalnuyu artery of the foot.
Venous system creates two vena cava. Cranial vena cava (v. cava cranialis) collects blood from the head (on the jugular veins), neck and thoracic limbs (branches of the subclavian vein), as well as the chest wall (right azygos vein in dogs and horses).
The left azygos vein in pigs and cattle runs directly into the heart. Caudal vena cava (v. cava caudalis) collects blood from the pelvic cavity (internal iliac veins), pelvic limb (external iliac vein) and paired abdominal organs (kidneys, adrenals, gonads). From odd abdominal organs (the gastrointestinal tract) veins empty into the portal vein, and it is in the liver, which produce excellent vascular network of the liver and liver already cleared of toxic products in the blood of hepatic veins enters the caudal vena cava. The colon is located in the pelvic cavity, so most of the blood from it enters the caudal vena cava, bypassing the liver barrier. This feature is used in the administration of soluble substances through the rectum.
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| Arterial, cardiovascular system of animals |
Arterial and venous part of the circulatory system are connected to each other by elements of the microvasculature, which include arterioles prekapillyarov, capillaries, and venules postkapillyary.These elements provide metabolism between blood and tissue and drainage shall deposit function.The movement of blood through the vessels is due to the work of the heart, the elastic-elastic properties of the arterial wall suction as the chest cavity (it is negative pressure), valvular veins (the folds of the inner layer of the vascular wall) and working muscles. Movement of blood vessels (blood flow) is characterized by parameters such as velocity, blood pressure, rhythmic contraction of the arterial wall (pulse). These parameters correspond to the laws of hydrodynamics (including Bernoulli law, which establishes the relationship between the diameter of the vessel, pressure and velocity). Thus, in the arteries, which have a minimum overall diameter, observed maximum pressure and flow velocity.
Regulation of blood flow is reduced to change the diameter of blood vessels that are in constant tone, and the number of circulating blood. This process involves the autonomic nervous system andcardiovascular reflex zones (nervous regulation), and adrenal hormones, pituitary, kidneys and central nervous system neurotransmitters (substances involved in the transmission of nerve impulses).At rest, about half the mass of blood is in the blood depots: 20% in liver, 16% in spleen and 10% in the subcutaneous tissue.
lymphatic system
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| lymphatic system, cardiovascular system of animals |
The lymphatic system is an auxiliary education venous system of the body and performs the following functions:
1-immune (associated with the activity of lymphocytes), drainage (removal of excess fluid from the tissues);
2-barrier-filtration (delay in lymph node tissues of toxins, bacteria, viruses and foreign particles);
3-transport (transport protein, some vitamins, fat).
The structure of the lymphatic system consists of lymph capillaries, vessels, nodes, collectors, trunks and ducts. Lymph - a colorless transparent liquid, similar in chemical composition to blood plasma. It contains proteins (less than in the blood), nitrogenous substances, glucose, salt, enzymes, hormones, vitamins and antibodies. In lymph no red blood cells and platelets, but it is able to coagulate due to the presence of fibrinogen and several other clotting factors. For lymphatic capillaries typical blind beginning in tissues. Association, they form the lymphatic heart. Lymphatic vessels are equipped with valves (like the valves in the veins), so that they have expansion and contraction. Lymph nodes are bean-shaped form and may be superficial and deep. Group lymph nodes that collect lymph from the total body surface, forming limfotsentr. The most important is limfotsentrami parotid (collects lymph from the brain skull), mandibular (collects lymph from the front of the skull), retropharyngeal (regionarny is for the whole head), superficial and deep neck (collect lymph from the neck), mediastinum (regionarny for thoracic ), axillary (collects lymph from the thoracic limbs), groin (collects lymph from the abdominal wall and pelvic limbs), mesenteric, and abdominal (regional to the abdominal cavity). The major lymphatic collectors have thoracic lymph duct (collects lymph from 3/4 of the body except the right half of the head, neck, right thoracic limb and the right half of the chest wall) right lymphatic duct (collects lymph from the right half of the head, neck, right thoracic limb and the right half of the chest wall). Both ducts open into kranyalnuyu vena cava. Thus the whole lymph collected in kranyalnuyu vena cava. In the process of moving lymph vessels involved but sticks feature thoracic cavity, the pressure difference in the lymph capillaries and ducts, muscles of the body, particularly the diaphragm, rhythmic contraction of lymph vessels and pulsation thoracic duct. Innervated lymph elements sympathetic nerve fibers, and the speed of movement of lymph varies reflex.
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| lymphatic system, cardiovascular system of animals |
Bodies hemo-lymphopoiesis and perform production of blood cells and thus participate in the maintenance of homeostasis and immune response. Stroma for all of this group is reticular tissue and parenchyma - lymphoid tissue. All bodies develop early in the course of individual development and the birth of the animal is already fully formed, but after birth are early involution (regression). Depending on the topography (location), functions and structure of all the organs of hemo-lymphopoiesis and be divided into central and peripheral. In central include bone marrow and thymus (thymus). These bodies formed cells that can differentiate cells own body against foreign (antihennezavisimoe differentiation).They are always located in well-protected areas of the body (bone marrow, thymus in the chest cavity on the chest).In peripheral organs hemo-lymphopoiesis and related lymph nodes, spleen, lymphoid formation gastrointestinal (tonsils, Peyyerovyh plaques, solitary follicles of the intestine), respiratory and urinary channels. All these bodies are located towards the possible introduction of infection or passing atypical substances produced in the body.
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