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• 13:44, 5 January 2023 Nikolas talk contribs created page 49. Mechanisms of vasoconstriction and vasodilatation (Created page with "We’ve talked a lot about vasoconstriction and vasodilation, but we haven’t yet discussed how these processes occur. Vessels have varying amount of smooth muscle in their walls, especially the arteries and arterioles. Vasoconstriction occurs when this smooth muscle contracts, and vasodilation occurs when this smooth muscle relaxes. I won’t describe the exact mechanism of smooth muscle contraction, but I will describe how different vasodilators and vasoconstrictors...") Tag: Visual edit
• 13:42, 5 January 2023 Nikolas talk contribs created page 48. Reflex control mechanisms of circulation (Created page with "== Cardiovascular reflexes == There are many cardiovascular reflexes involved in the normalization of rapidly changing blood pressure. These reflexes are not involved in the long-term regulation of blood pressure. Like all reflexes these reflexes follow the following sequence of events: # A stimulus occurs, which stimulates a receptor # An afferent nerve is activated # The afferent nerve stimulates a reflex centre, often in the CNS # The reflex centre stimulates an eff...") Tag: Visual edit
• 13:42, 5 January 2023 Nikolas talk contribs created page 47. The function and importance of baroreceptors in the regulation of circulation (Created page with "Baroreceptors are small receptors located within the walls of vessels. Like the name suggests these receptors detect changes in the blood pressure (by detecting changes in the stretch of the wall of the vessels). If a baroreceptor detects a change in blood pressure it can send a feedback signal to the autonomic nervous system to regulate the blood pressure back to normal. The baroreceptors are especially important in many cardiovascular ''reflexes'' which regulate the b...") Tag: Visual edit
• 13:41, 5 January 2023 Nikolas talk contribs created page 46. Autoregulation of blood flow in tissues and organs (Created page with "The cerebral, coronary and renal circulations (and so some extent the skeletal muscle circulation) are autoregulated, meaning that their blood flow is regulated so that it is constant independently of the arterial blood pressure. The mechanism of autoregulation is explained in the previous topic and in the topics of the respective circulations. Category:Physiology 1") Tag: Visual edit
• 13:41, 5 January 2023 Nikolas talk contribs created page 45. Local control of the vascular smooth muscle (Created page with "Most organs and tissues can regulate their own blood flow in response to their own needs. These needs can be: * They need more oxygen * They need more nutrients * They need to remove more CO2 * They need to remove more H+ * etc. The way tissues regulate their own blood flow is called ''local regulation''. This regulation is important to ensure that blood flow is sufficient to meet the tissues’ metabolic needs, but it is also important to ensure that the blood flow is...") Tag: Visual edit
• 13:40, 5 January 2023 Nikolas talk contribs created page 44. Control mechanisms of the circulatory system. General considerations (Created page with "The circulatory system is regulated by many different mechanisms: * Neuronal mechanisms * Cardiovascular reflexes * Humoral mechanisms * Local mechanisms == Neuronal mechanisms == As already described, many parts of the circulatory system are innervated by the parasympathetic and, more importantly, the sympathetic nervous system. This includes the heart and blood vessels. Generally, sympathetic activation causes: * Increased heart rate * Increased myocardial contracti...") Tag: Visual edit
• 13:37, 5 January 2023 Nikolas talk contribs created page 43. Nervous control of the heart (Created page with "There are two major regulatory nervous systems in the body, the parasympathetic and the sympathetic. The heart is innervated by both systems. The two systems have mostly opposite effects. We usually think of the parasympathetic and sympathetic systems as being either “on” or “off”, but that’s not the case. Both systems can be active anywhere from 0% to 100% of full activity. == Parasympathetic activation of the heart == The major parasympathetic nerve of the...") Tag: Visual edit
• 13:37, 5 January 2023 Nikolas talk contribs created page 42. Skeletal muscle circulation. Cutaneous circulation (Created page with "== Skeletal muscle circulation == The blood flow to the skeletal muscle is not low in rest, when it accounts for 15% of the cardiac output. However, during exercise the blood flow may increase 15 – 25 fold. During exercise: During exercise the sympathetic nervous system will be activated. This has multiple effects: * The heart will be stimulated, so that cardiac output increases * The splanchnic blood flow will be reduced * Veins will vasoconstrict, which increases...") Tag: Visual edit
• 13:36, 5 January 2023 Nikolas talk contribs created page 41. Splanchnic circulation (Created page with "The splanchnic organs include the stomach, small intestine, large intestine, pancreas, spleen, kidney and liver. The splanchnic circulation refers to all blood flow which originates from the celiac trunk, superior mesenteric artery and inferior mesenteric artery. The splanchnic organs receive a lot of blood flow in rest, as it is during rest that the gastrointestinal tract and kidneys works the most and therefore requires the most blood. In rest around 20% of the blood...") Tag: Visual edit
• 13:35, 5 January 2023 Nikolas talk contribs created page 40. Cerebral circulation. The concept of “blood-brain barrier” (Created page with "== Cerebral circulation == The cerebral circulation supplies the brain with blood. It originates from four large arteries, two carotid and two vertebral arteries. These four arteries form a structure called the ''circle of Willis'' at the base of the brain. From the circle of Willis arteries which supply the brain originate. The brain constitutes about 2% of the body weight, but it receives 15% of cardiac output in rest, around 700 mL/min. === Regulation of cerebral ci...") Tag: Visual edit
• 13:35, 5 January 2023 Nikolas talk contribs created page 39. The coronary circulation (Created page with "The coronary circulation is the one which supplies the heart, especially the myocardium, with oxygenated and nutrient-rich arterial blood. The myocardium doesn’t receive any oxygen or nutrients from the blood which is pumped out by the heart, so it needs its own circulation. The myocardium requires a lot of oxygen, as it is contracting all the time with large force. All tissues supplied by arteries can increase the amount of oxygen they extract from the blood if neces...") Tag: Visual edit
• 13:34, 5 January 2023 Nikolas talk contribs created page 38. The pulmonary circulation. Control of lung vessels (Created page with "== Pulmonary circulation == The pulmonary circulation is responsible for transporting deoxygenated blood to the lungs to be oxygenated, and to transport the blood back to the heart. When blood passes through the capillaries around the alveoli oxygen enters the blood from the alveoli while CO2 leaves the blood and enters the alveoli. The pulmonary circulation also partly provides nutrients and oxygen to the lung tissue itself, but the lungs have another circulation which...") Tag: Visual edit
• 09:57, 5 January 2023 Nikolas talk contribs created page 37. Circulation in the vein. Effect of gravity on circulation (Created page with "== Venous circulation == The venous circulation has two roles: * To return blood from the tissues to the heart * To store blood When we talk about “storing” blood in the venous circulation we don’t mean that venous blood lies stagnated in the venous circulation. We mean rather that the diameter of the veins is very large, which means that the veins contain a lot of blood volume. === Structure of veins: === Veins have a thinner vessel wall than the arteries. Thei...") Tag: Visual edit
• 09:57, 5 January 2023 Nikolas talk contribs created page File:Jugular pulse curve.png
• 09:57, 5 January 2023 Nikolas talk contribs uploaded File:Jugular pulse curve.png
• 09:56, 5 January 2023 Nikolas talk contribs created page File:The phases of the Valsalva manoeuvre.png
• 09:56, 5 January 2023 Nikolas talk contribs uploaded File:The phases of the Valsalva manoeuvre.png
• 09:54, 5 January 2023 Nikolas talk contribs created page 36. The properties, production and the movement of lymph (Created page with "== Lymphatic system == The lymphatic system contains a fluid called ''lymph''. The system has multiple functions: * Draining excess interstitial fluid from the interstitium into the blood * Carrying proteins and other large proteins, which are too large to be absorbed into the capillaries. * Absorbing fats from the <abbr>GI</abbr> tract * Transport of lymphocytes, antibodies and pathogens All tissues have lymphatic vessels, which eventually drain into the thoracic duct...") Tag: Visual edit
• 09:53, 5 January 2023 Nikolas talk contribs created page 35. Circulation through the capillaries (Created page with "== Structure of the microcirculation == The microcirculation is the blood flow in the smallest vessels, the arterioles, metarterioles, capillaries, and venules. It is at the level of the microcirculation where nutrients and gases are exchanged with the tissues. Blood flows from the arterial system and ends in the arterioles. So-called ''metarterioles'' branch off from the arterioles and connect the arterioles and the venules. Capillaries branch off from the metarteriole...") Tag: Visual edit
• 09:52, 5 January 2023 Nikolas talk contribs created page File:Starling forces.png
• 09:52, 5 January 2023 Nikolas talk contribs uploaded File:Starling forces.png
• 09:52, 5 January 2023 Nikolas talk contribs created page File:Starling equation 2.png
• 09:52, 5 January 2023 Nikolas talk contribs uploaded File:Starling equation 2.png
• 09:51, 5 January 2023 Nikolas talk contribs created page File:Starling equation 1.png
• 09:51, 5 January 2023 Nikolas talk contribs uploaded File:Starling equation 1.png
• 09:51, 5 January 2023 Nikolas talk contribs created page File:Structure of the microcirculation.png
• 09:51, 5 January 2023 Nikolas talk contribs uploaded File:Structure of the microcirculation.png
• 09:48, 5 January 2023 Nikolas talk contribs created page 34. The arterial and the venous pulse. Basic principles of hemodynamics. (Created page with "When we talk about the pulse, we refer to the ''arterial'' pulse. The arterial pulse is the periodic, tactile vibration which can be felt at different points on the body. The pulse is the result of the heart pumping. When the heart pumps, a pressure wave propagates along the arterial blood vessels, and when this pressure wave reaches a pulse point a pulse can be felt. The pulse rate is the same as the heart rate in normal cases. The arterial pulse wave which propagates...") Tag: Visual edit
• 09:48, 5 January 2023 Nikolas talk contribs created page File:Arterial pulse curve.png
• 09:48, 5 January 2023 Nikolas talk contribs uploaded File:Arterial pulse curve.png
• 09:45, 5 January 2023 Nikolas talk contribs created page 33. Arterial blood pressure. Determinants of normal arterial blood pressure (Created page with "== Circulatory system == The circulatory system is divided into many different parts. The systemic circulation is the one which supplies all tissues of the body with oxygenated blood and nutrients. The vast majority of blood is in the systemic circulation. The systemic circulation begins at the aorta and ends at the superior and inferior vena cavae. It has an arterial and a venous side, where the arterial side contains oxygen-and-nutrient-rich blood and the venous side c...") Tag: Visual edit
• 09:43, 5 January 2023 Nikolas talk contribs created page File:MAP formula 2.png
• 09:43, 5 January 2023 Nikolas talk contribs uploaded File:MAP formula 2.png
• 09:43, 5 January 2023 Nikolas talk contribs created page File:MAP formula.png
• 09:43, 5 January 2023 Nikolas talk contribs uploaded File:MAP formula.png
• 09:42, 5 January 2023 Nikolas talk contribs created page File:Blood pressure in the different parts of the circulatory system..png
• 09:42, 5 January 2023 Nikolas talk contribs uploaded File:Blood pressure in the different parts of the circulatory system..png
• 09:41, 5 January 2023 Nikolas talk contribs created page File:Organisation of the circulatory system.png
• 09:41, 5 January 2023 Nikolas talk contribs uploaded File:Organisation of the circulatory system.png
• 09:39, 5 January 2023 Nikolas talk contribs created page 32. The heart-lung preparation (Starling’s laws) (Created page with "== Heart-lung preparation == Starling made the so-called heart-lung preparation, where the heart and lungs are disconnected from the systemic circulation and the systemic circulation is replaced with artificial tubes. The heart will pump blood through these tubes and back into the right atrium. The lungs are ventilated artificially. The resistance of the artificial tube system could be altered, which simulates changes in the peripheral vascular resistance in vivo. The h...") Tag: Visual edit
• 09:39, 5 January 2023 Nikolas talk contribs created page 31. Ventricular wall tension and the Laplace relationship (Created page with "As explained in the previous topic, the tension in the ventricular wall is directly related to the ventricle’s oxygen requirement. When the wall tension increases, the oxygen requirement increases too. === LaPlace’s law === thumb|LaPlace's law LaPlace’s law describes the relationship of pressure, radius of the lumen, the thickness of the wall and the wall tension in hollow organs like the ventricles and blood vessels. LaPlace’s law is...") Tag: Visual edit
• 09:38, 5 January 2023 Nikolas talk contribs created page File:LaPlace's law.jpg
• 09:38, 5 January 2023 Nikolas talk contribs uploaded File:LaPlace's law.jpg
• 09:34, 5 January 2023 Nikolas talk contribs created page 30. Metabolism and energetics of cardiac muscle (Created page with "== Myocardial metabolism == The heart requires a lot of energy, not just to contract but also to maintain ion gradients. The myocardium performs only ''aerobic'' (oxygen-dependent) metabolism and not ''anaerobic'' (oxygen-independent) metabolism. This means that the myocardium requires large amounts of oxygen. The oxygen is supplied by the coronary circulation. When the myocardium works harder it requires more energy and therefore more blood, so the coronary circulation...") Tag: Visual edit
• 09:33, 5 January 2023 Nikolas talk contribs created page 29. Cardiac output. Measurement, normal standards and physiological variations (Created page with "== Important terms == The cardiac output (CO) is the amount of blood the heart pumps out every minute. It’s normally 5 litres per minute. The end-systolic volume (ESV) is the amount of blood which is left inside the left ventricle after systole. The end-diastolic volume (EDV) is the amount of blood which is left inside the left ventricle after diastole, right before systole begins. The stroke volume (SV) is the amount of blood the heart ejects with each cardiac cycl...") Tag: Visual edit
• 09:33, 5 January 2023 Nikolas talk contribs created page File:Fick principle.png
• 09:33, 5 January 2023 Nikolas talk contribs uploaded File:Fick principle.png
• 09:32, 5 January 2023 Nikolas talk contribs created page File:Formula for MAP.png
• 09:32, 5 January 2023 Nikolas talk contribs uploaded File:Formula for MAP.png
• 09:31, 5 January 2023 Nikolas talk contribs created page 28. The heart sounds. Phonocardiography (PCG) (Created page with "The heart makes sounds when it beats. More specifically, what we consider “heart sounds” are actually the sound of turbulent blood flow which occurs as the valves close. These sounds are very silent but can be heard with a stethoscope, which amplifies the sounds. This is called ''auscultation'' and is an important part of physical examination of the patient. The heart makes two sounds in healthy people. These are called the first and second heart sounds, or S1 and S...") Tag: Visual edit