ABSTRACT The document is an assignment in Biology that is mainly explaining transport in man under the blood circulatory system. Author: Blessed SIlwimba N 11A Biology HOLIDAY ASSIGNMENT Question one: Transport in man Question 1 Transport in man; the blood circulatory system a) Blood is a red liquid which consists of the suspension of cells in aqueous solution some of them are red blood cells, white blood cells and platelets. Red blood cells also known as erythrocytes are biconcave discs which consist of spongy cytoplasm in an elastic membrane, they are produced in the red bone marrow, when they are produced they contain a nucleus which is later lost thus they have no nuclei and in their cytoplasm is a red pigment called hemoglobin which gives blood its colour, it has an infinity of oxygen and this is because of their absence of nuclei which increases the surface area, in transportation of oxygen its hemoglobin combines with oxygen to form oxy-hemoglobin. White blood cells are also called leucocytes, they are classified into two types which are agranulocytes and granulocytes. Agranulocytes are leucocytes that do not show granules in their cytoplasm e.g. neutrophils and lymphocytes. Granulocytes are leucocytes that show granules in their cytoplasm. E.g. neutrophils, basophils and eosinophil, unlike erythrocytes they contain a nucleus and are larger and fewer than red blood cells, and they can change their form, most of them are of a type called phagocytes which can move by flowing action of their cytoplasm and can pass out of blood capillaries by squeezing between the cells of the capillary wall. They ingest and destroy bacteria and dead cells by flowing around, engulfing and digesting them. Platelets are fragments of the red bone marrow they are also known as thrombocyte. Platelets play an important role in clotting action of the blood. There are about 400,000 of the millimeter of blood and they appear as tiny round or oval structures, they form temporary platelet plays to stop bleeding when injury occurs, they also secrete clotting factors to promote blood clotting. b) The heart is a muscular pumping organ which pumps blood to all parts of the body, it has several parts which facilitate pumping. It has a vena cava that carries deoxygenated blood into the right atrium. The pulmonary artery which transports deoxygenated blood to the lungs, unlike the pulmonary artery the pulmonary vein transports oxygenated blood to the heart, the right atrium is a chamber that pumps blood to that right ventricle through tricuspid valve. The Aorta transports blood to all parts of the body, the tricuspid valve opens when the right atrium pumps deoxygenated blood into the right ventricle while the bicuspid valve opens when the left atrium pumps oxygenated blood into the left ventricle. The septum separates the heart into the left and right side, the semilunar valves open for blood to flow out of the heart. c) There are many diseases of the circulatory system some of them are caused by unhealthy diet while others are genetic. Atherosclerosis is the hardening and narrowing of the arteries, it is typically caused by a diet high in fat which leaves fatty deposit stuck together and make the arteries hard and less flexible. It leads to blood pressure which can lead to strokes, it can be managed by having a diet consisting less fat, by taking the required amount of fat needed in the body. Another circulatory disease is coronary thrombosis which is the forming of blood clot (thrombus) in arteries normally caused by stress, stress releases adrenaline which increases heart rate and blood pressure. It occurs as a result of blood clotting inside vessels preventing blood flow, this may lead to heart attack, if it is the coronary artery which is blocked with a thrombus or it may be cerebral thrombosis. If blockage occurs in artery going to the brain then all the parts of the brain receiving oxygenated blood will be damaged resulting into death. It can be managed or prevented by following a healthy diet and exercise plan as recommended by their physician after experiencing coronary thrombosis. Below is an illustration of coronary thrombosis. Hypertension is another circulatory disease of which blood applies too much force against the walls of the blood vessels, it is normally caused by taking a diet containing too much saturated fats, it can be managed by reducing salt, usually the amount of salt taken in a day is 9g and 12g but the recommend is 5g per day, moderating alcohol at least two drinks for men and 1 for women each day, eating more fruits and vegetables, having regular exercise at least 30 minutes each day. The image below illustrates hypertension. Another disease is Peripheral artery disease (PAD) which refers to diseases of the blood vessels located outside the heart and brain. They are most often caused by a buildup of fatty deposits in the arteries. PAD is also known as peripheral arterial disease or peripheral vascular disease (which includes both arteries and veins). It can be managed by Regular physical activity which is the most effective treatment, a doctor will often recommend a program of supervised exercise training. The patient may have to start off slowly. Simple walking regimens, leg exercises, and treadmill exercise programs three times a week. Diet changes and adjustments can also help manage PAD as many individuals with PAD have elevated cholesterol levels. A diet low in saturated fat, trans fat, and cholesterol, as well as plenty of fruit and vegetables, can help lower blood cholesterol levels. Smoking cessation is also one of the management ways as tobacco smoke greatly increases the risk of PAD, smokers may have four times the risk of developing PAD than nonsmokers. Stopping smoking will help to slow the progression of PAD and other heart-related diseases. There are various things that are needed in blood clotting such as thromboplastin which in the presence of calcium ions activates the inactive prothrombin to thrombin, vitamin k which is essential for the synthesis of thrombin by the liver. Thrombin catalyses’ the conversion of fibrinogen to insoluble fibrous fibrin. Fibrin forms a mesh or network of fibres on a wound which the forms a clot. It is important to screen blood before transfusion as to prevent transmitting infections to the person receiving, it is also important as to know the blood groups that can share that blood type, to also remove all impurities that might occur in the blood. Blood is also tested for certain proteins (antibodies) that may cause problems in a person receiving a blood transfusion.