Transcript Circulation
The 3 main parts of The Circulatory system The Heart The Blood Vessels Blood The 3 main parts of The Circulatory system Blood circulates through a network of vessels throughout the body to: – provide individual cells with oxygen and nutrients – help dispose of metabolic wastes. The heart pumps the blood to move it through the blood vessels. What is Blood tissue? Blood is made up of about 45% solids (cells) and 55% fluids (plasma). The plasma is largely water, containing proteins, nutrients, hormones, antibodies, and dissolved waste products. Functions of blood and circulation: Circulates OXYGEN and removes Carbon Dioxide. Provides cells with NUTRIENTS. Removes the waste products of metabolism to the excretory organs for disposal. Protects the body against disease and infection. Clotting stops bleeding after injury . Transports HORMONES to target cells and organs. Helps regulate body temperature. Parts of The Heart The Atria -Receiving Chambers The Ventricles -Pumping Chambers The Valves -Controls Flow The Septum -Divides the Heart The Heart The heart is a hollow, muscular organ about the size of a fist It beats over 100,000 times a day to pump blood around the body's 60,000 miles of blood vessels. The right side of the heart receives blood and sends it to the lungs to be oxygenated. The left side receives oxygenated blood from the lungs and sends it out to the tissues of the body. The Heart has three layers: The ENDOCARDIUM (inner layer), The EPICARDIUM (outer layer), and MYOCARDIUM (middle layer). The heart is protected by the PERICARDIUM which is the protective membrane surrounding it. The heart has FOUR CHAMBERS, in the lower heart the right and left Ventricles, and in the upper heart the right and left Atria. In a heart beat... In a normal heart beat the atria contract while the ventricles relax, then the ventricles contract while the atria relax. There are VALVES through which blood passes between ventricle and atrium, these close in such a way that blood does not backwash during the pauses between ventricular contractions. The walls of the left ventricle are thicker as it has to pump blood to all the tissues, compared to the right ventricle which only pumps blood as far as the lungs. A single heart beat The right and left ventricles are divided by a thick wall (the VENTRICULAR SEPTUM), babies born with "hole in the heart" have a small gap here, which is a problem since oxygenated and deoxygenated can blood mix. All babies have this hole until birth. Normally, the foramen ovale closes at birth and heals shut very quickly. If this flap of tissue fails to cover the hole and heal completely the child has a “hole in the Heart” Electrical Stimulus • • • • SV node AV node Bundle of His Purkinje Fibres http://web.buddyproject.org /web019/web019/heart.html CHECK THIS OUT! Types of Blood Vessels Arteries -Carry blood away from the Heart -The Aorta is the largest artery Veins -Carry blood to the Heart -Veins contain valves -The Vena Cava is the largest vein Capillaries -Known as the “Distribution Pipes” Arteries Thick, muscular, hollow tubes which are highly ELASTIC – allows them to DILATE (widen) and CONSTRICT (narrow) as blood is forced down them by the heart Arteries branch and re-branch, becoming smaller until they become small ARTERIOLES which are even more elastic. – Arterioles force blood into the capillaries (high pressure). Veins VENULES (very small veins) merge into VEINS which carry blood back to the heart (low pressure). The vein walls are similar to arteries but thinner and less elastic. Veins possess valves at intervals to prevent the backflow of blood as it moves against the force of gravity back to the heart. Valves only open one direction Faulty valves and weak vein walls can lead to varicose veins How do veins return blood to the heart if they are not muscular of elastic? 3 strategies: – Valves prevent backflow (only open one way) – Heart is pumping and pushing blood from behind to keep it moving forward – As muscles around the vein contract, the veins are squeezed forcing the blood along CAPILLARIES Distribute the nutrients and oxygen to the body's tissues (blood pressure) and remove deoxygenated blood and waste by diffusion. They are extremely thin, the walls are only one cell thick and connect the arterioles with the venules (blood cells travel single-file). No cell in the body is more than 2 cells away from a capillary Blood is made up of: plasma (which accounts for about 3 liters) red blood cells white bloods cells and platelets. Vitamins, electrolytes and other nutrients are dissolved in the blood and carried to the body's cells and organs. The Composition of Blood Blood Composition The Plasma (Fluid) makes up 55% of the blood volume. 60 50 40 30 The Solids (Cells) make up 45% of the blood volume. 20 10 0 Plasma Solids Blood Plasma 97% Water Other 3% -Antibodies and Proteins - Nutrients and Wastes Blood Solids Red Blood Cells(ERYTHROCYTES) - Carry oxygen - Contain Hemoglobin White Blood Cells (LEUKOCYTES) -Attack bacteria & other invaders Platelets (THROMBOCYTES ) -Control the blood clotting process ERYTHROCYTES (red cells) Small red disk shaped cells. They contain HAEMOGLOBIN, which combines with oxygen in the lungs and is then transported to the body's cells. The haemoglobin then returns carbon dioxide waste to the lungs. Erythrocytes are formed in the bone marrow in the knobby ends of bones. LEUKOCYTES (white cells) Help the body fight bacteria and infection. When a tissue is damaged or has an infection the number of leukocytes increases. Leukocytes are formed in the small ends of bones. Leukocytes can be classed as granular or non granular. There are three types of granular leukocytes: – eosinophils – neutrophils – and basophils There are three types of non-granular: – monocytes – T-cell lymphocytes – and B-cell lymphocytes White Blood Cells THROMBOCYTES (platelets) Aid the formation of blood CLOTS by releasing various protein substances. When the body is injured thrombocytes disintegrate and cause a chemical reaction with the proteins found in plasma, which eventually create a thread like substance called FIBRIN. The fibrin then "catches" other blood cells which form the clot, preventing further loss of blood and forms the basis of healing. How much blood is in the average person? Enough to fill one or two one-gallon milk jugs. Blood accounts for about seven percent of human body weight, and its density is only slightly more than that of pure water. A man weighing 154 pounds (70 kilograms) would have about 5.5 quarts (5.2 liters) of blood. A woman weighing 110 pounds (50 kilograms) would have about 3.5 quarts (3.3 liters) of blood. How much blood can a human lose? An adult human can lose 10-15% without clinical damage. If one loses 30% it can be fatal (haermorraghic [shock due to loss of blood]). An "average" adult male has some 5 litres of blood. Sudden loss of 1/3 of his blood can be fatal. However if the lose rate us slow (say: 24 hours) he can lose as much as 2/3 of the blood with much risk (well documented). So it's not only the amount of blood that one is losing but, the rate one loses it. It's also a matter of maintaining the blood pressure. Interesting.... In one day, your blood travels nearly 12,000 miles. Your heart beats around 35 million times per year. Your heart pumps a million barrels of blood during the average lifetime -enough to fill three supertankers. The spleen This is a large flat oval organ located below the diaphragm, it's main function is to STORE BLOOD. The size of the spleen can vary, for example it may enlarge when the body is fighting infection also it's size tends to decrease with age. It is a non-vital organ and it is possible to survive after removal of the spleen. – Perinicious anaemia is a Vitamin B12 deficiency resulting in a reduction in number of erythrocytes. – Aplastic anemia is a failure of the bone marrow to produce the enough red blood cells. – Septicaemia - bacterial toxins in blood. Vascular System Problems Aneurysm Arteriosclerosis Atherosclerosis Varicose veins Anemia Aneurysm A fluid-filled bulge found in the weakened wall of an artery which may eventually rupture and lead to cell death (common cause of strokes) Arteriosclerosis Degeneration of blood vessel due to accumulation of fat deposits along the inner wall. Atherosclerosis Blood vessels thicken, harden, wind, and lose their elasticity Varicose Veins Weakening of the veins that causes blood to pool and vessels to bulge. Anemia Reduction of blood oxygen due to low levels of hemoglobin or poor red blood cell production Resources http://www.studystack.com/studytable -896 From the Heart video Human Blood slide show Credits Graphics courtesy of Crystalcafe.com & The Franklin Institute online. Presentation by Steve Kennette Thanks to: Spartanburg School District #5 Duncan, S. C.