The functions of blood are ?
Blood is the primary transport medium for a variety of substances that travel throughout the body.
- Oxygen is carried from the lungs to the cells of the body in red blood cells.
- Carbon dioxide is carried from the body’s cells to the lungs.
- Nutrients such as glucose, amino acids, vitamins and minerals are carried from the small intestine to the cells of the body.
- Cellular wastes such as water, carbon dioxide, lactic acid and urea are carried in the blood to be excreted.
- Hormones, which are internal secretions that help to control important body processes, are transported by the blood to target organs.
White blood cells are collectively called leucocytes and they play a major role in combating disease and fighting infection.
Blood helps to regulate heat in the body by absorbing large quantities of heat produced by the liver and the muscles. This is then transported around the body to help to maintain a constant internal temperature. Blood also helps to regulate the body’s pH balance.
Clotting is an effective mechanism in controlling blood loss from blood vessels when they have become damaged as in a cut. Specialised blood cells called thrombocytes, or platelets, form a clot around the damaged area to prevent the body from losing too
- Transport, heat regulation, secretion and clotting
- Defence, transport, absorption and clotting
- Transport, heat regulation, defence and clotting
- Sensation, heat regulation, defence and clotting
What makes up 55% of the composition of blood?
The blood consists of a variety of blood cells and a watery substance called blood plasma.
Blood is composed of 55% of fluid or plasma which is a clear, pale yellow, slightly alkaline fluid consisting of the following substances:
- 91 per cent of plasma is water
- 9 per cent remaining consists of dissolved blood proteins, waste, digested food materials, mineral salts and hormones
• 45% of blood is made up of the blood cells erythrocytes, leucocytes and thrombocytes.
- blood cells
Plasma is a straw-coloured fluid consisting of about 91% water.
7% of plasma is made up of proteins, most of which are synthesized by the liver. The plasma proteins include albumins, globulins and fibrinogen.
- Albumins regulate osmotic pressure. This helps to maintain the water balance between the blood and the tissues, so regulating blood volume.
- Globulins; This protein group includes antibodies (immunoglobulins) that play a vital role in immunity by attacking antigens. Alpha and beta globulins transport iron, fats and fat-soluble vitamins.
- Fibrinogen plays a vital role in blood clotting (covered later in this section).
2% consist of other solutes.
Which blood cell designed to protect the body against infection?
Components of Blood
Which of the following is a unique part of the structure of a vein?
Arteries take blood away from the heart (memory hint: Arteries = Away).
Arteries divide to form very small vessels called arterioles. Arterioles branch further to become capillaries.
Arteries expand as the blood is pumped from the heart, and then recoil to force the blood through the vessel. Arteries therefore have to be elastic and have the ability to contract.
Veins take blood back to the heart. Venous blood is under less pressure than arterial blood.
The lumen in a vein is larger than in an artery and the vein wall is weaker and thinner. This is particularly noticeable in the tunica media. Due to the reduced pressure under which the blood flows in the veins, most veins contain valves.
Valves prevent the back-flow of blood, so aiding its return to the heart.
- thick muscular wall
- thick elastic wall
- single cell layer thick
What is the function of the capillary?
Arteries divide to form arterioles, which continue to divide, getting smaller and smaller, until they become capillaries.
Capillaries are formed by the multiple division of the arteries. The capillaries allow the exchange of nutrients and waste and then, as the vessels leave the capillary network, they join to form venules.
Venules continue to merge until they become veins.
- prevent back-flow of blood
- supply cells and tissues with nutrients
- carry only deoxygenated blood
- carry only oxygenated blood
What is the function of an artery?
- carry blood towards the heart
- carry deoxygenated blood
- carry oxygenated blood
- carry blood under low pressure
Which is the correct sequence of structures through which the blood flows?
Arteries contain oxygenated blood. The exception to this is the pulmonary arteries. The pulmonary arteries take deoxygenated blood from the heart to the lungs.
Veins contain deoxygenated blood. The exception is the pulmonary veins. The pulmonary veins take oxygenated blood from the lungs to the heart.
- arteries, arterioles, capillaries, venules, veins
- arterioles, arteries, capillaries, veins, venules
- veins, venules, capillaries, arterioles, arteries
- venules, veins, capillaries, arteries, arterioles
What effect does the circulatory system have on the skin and muscles?
- It reduces the blood supply to the skin and muscle, nourishing the cells causing less cell renewal.
- The blood supply to the skin and muscle is reduced, nourishing the cells causing improved cell renewal.
- An increase of the blood supply to the skin and muscle nourishes the cells and causes less cell renewal.
- It would increase the blood supply to the skin and muscle, nourishing the cells and improving cell renewal.