TRANSPORT SYSTEMS Flashcards
BLOOD
- The blood in the human body carries substances
- distributes it around the body through a large network of blood vessels.
- In adults, there are 5 to 6 litres of blood in the body
- which consists of two parts which are fluid called plasma and blood cells suspended in the plasma.
Plasma
- THE LIQUID (non cellular) COMPONENT OF BLOOD
- Plasma contains 90 percents of water with a huge range of substances dissolved or suspended within it.
- This includes nutrients absorbed from the alimentary canal, oxygen absorbed from the lungs, chemicals synthesised by body cells for instance hormones and waste materials produced by all cells to be eliminated from the body by excretion.
Blood cells
There are three distinct groups which are classified according to their functions.
• Erythrocytes which is known as the red blood cells distribute oxygen and to a lesser extent, carbon dioxide between the lungs as well as all the body cells.
• Leukocytes which is known as the white blood cells are mainly concerned with the protection of the body to fight against infection and foreign and unknown substances.
• There are several types of leukocytes which carry out protective functions is several ways. there is a cell that is larger and there are less numerous compared to the erythrocytes.
• Platelets which is known as thrombocytes are tiny cell fragments that play an essential part in the body clotting.
CARDIOVASCULAR SYSTEM
- The cardiovascular system consists of a network of blood vessels and the heart.
- The system circulating blood and lymph through the body which consist a network of the heart, blood vessels, blood, lymph and the lymphatic vessels and glands.
Blood vessels
There are three types of vessels which are:
• arteries, which carry blood away from the heart
• Veins, which return blood to the heart
capillaries, which link the arteries and veins
• Capillaries are the tiny blood vessels that are structured with very thin walls that consist only one layer of cells enabling an exchange of substances such as nutrients, oxygen and cellular waste products that is between the blood and body tissues.
• Blood vessels form a massive network that transports blood:
the lungs (the pulmonary circulation), where oxygen is absorbed from the air in the lungs and the same time, the carbon dioxide is excreted from the blood into the air.
• Cells in all other parts of the body (general or systemic circulation)
Heart
- The heart is a muscular sac which consists of four chambers which are the left and right atrium and the left and right ventricle.
- This pumps the blood to distribute around the body and maintain the blood pressure.
- The heart muscle is involuntary which means that it is not under conscious control.
- At rest, the heart will squeeze which contracts between 65 and 75 times per minute. • The rate is will raise when the body demands oxygen are increased which occurs for example during exercise.
- The rate at which the heart beats can be counted by taking the pulse. It can be easily be felt from the superficial artery which can be pressed gently against a bone, usually at the wrist.
LYMPHATIC SYSTEM
The lymphatic system consists of a series of lymph vessels, which begin-ended tubes in the tissue spaces between the blood capillaries and tissue cells. The structure of this is that there are similar veins and blood capillaries but the pores in the walls of the lymph capillaries are larger than those of the blood capillaries. Lymph is tissue fluid that also contains material drained from tissue spaces which include plasma proteins and sometimes the bacteria or cell debris. It is transported along lymph vessels and returned to the blood bloodstream near the heart. There are collections of lymph nodes situated at various points along the length of the lymph vessels. Lymph is filtered as it passes through these nodes which removes microbes and other materials. Other lymphatic organs include the spleen and the thymus.
