8: Transport in Humans Flashcards
Why do small organisms not need a transport system?
The substances are transported throughout their body by diffusion or streaming of the cytoplasm.
Why do large multicellular organisms need a transport system?
Cells in different parts of the body are far away from each other. Diffusion is too slow and becomes inefficient. Therefore, to ensure the supply of useful substances to target cells and removal of waste from the body, a transport system is developed in them.
What are the systems included in the human transport system?
Circulatory system, lymphatic system
What are the three main parts of the human circulatory system and their functions?
Blood: it carries useful substances and waste to and from body cells.
Blood vessels: they form a system of tubes that distribute blood throughout the body; the smallest blood vessels allow exchange of materials between blood and body cells.
Heart: it acts as a pump to give the force to drive blood throughout the body.
What are the four components of blood?
Plasma, red blood cells, white blood cells, blood platelets
What are the properties and functions of plasma?
Plasma contains mostly water with various substances dissolved or suspending in it.
It is the medium for transporting substances throughout the body, and it helps distribute heat throughout the body to maintain body temperature.
List 7 substances that the plasma transports.
Water, carbon dioxide (both as a gas and in the from of hydrogen carbonate ions), nutrients, urea, hormones, antibodies, and fibrinogen.
What are the shapes of red blood cells, white blood cells, and blood platelets?
Red blood cells have a biconcave disc shape, while white blood cells and blood platelets have irregular shape.
What are the sizes of red blood cells, white blood cells, and blood platelets?
Phagocytes are the largest type of cell, followed by lymphocytes and red blood cells having similar size. Blood platelets have the smallest size.
Rank the number per volume of red blood cells, white blood cells, and blood platelets in blood.
Red blood cells are the most abundant, followed by blood platelets and lastly white blood cells.
Compare the nuclei of mature red blood cells, white blood cells, and blood platelets.
Mature red blood cells and blood platelets have no nuclei. Phagocytes have a lobed nucleus while lymphocytes have a large round nucleus.
Rank the lifespan of mature red blood cells, white blood cells, and blood platelets.
Red blood cells have the longest lifespan, followed by blood platelets and lastly white blood cells.
Compare the colour of mature red blood cells, white blood cells, and blood platelets.
Mature red blood cells are red in colour due to the presence of haemoglobin. White blood cells and blood platelets are colourless.
Compare the sites of production and destruction of red blood cells, white blood cells, and blood platelets.
Red blood cells and blood platelets are produced in the bone marrow and destroyed in the liver and spleen. White blood cells are produced in the bone marrow and spleen; some of them are killed by germs and passed out through faeces.
What is haemoglobin in red blood cells broken down into?
Iron, which is reused to make red blood cells, and bile pigment, which is excreted as part of bile.
What are the characteristics of a blood smear of a patient with anaemia?
There is a reduced number of red blood cells, since anaemia is the deficiency of haemoglobin or red blood cells.
What are the characteristics of a blood smear of a patient with leukaemia?
There is an increased number of white blood cells, since leukaemia usually leads to the production of a large number of abnormal white blood cells.
What is the function of red blood cells?
They contain haemoglobin which carries oxygen from the lungs to all parts of the body.
What is the function of white blood cells?
They protect our body against diseases by killing germs.
What is the function of blood platelets?
They are involved in blood clotting which prevents further blood loss and the entry of germs into our body through the cut wounds.
What are 5 types of blood vessels in humans?
Arteries, arterioles, capillaries, venues, and veins
What is the largest artery in humans?
Aorta
What is the largest vein in humans?
vena cava
What are the layers of the walls of arteries and veins?
There are 4 layers:
The outer layer is fibrous tissue, the middle layers consist of smooth muscles and elastic tissues, while the inner layer is the endothelium.
What are the differences in thickness of the layers of the walls of arteries and veins?
Arteries have a thicker layer of smooth muscles and elastic tissue and a smaller lumen, while veins have a thinner layer of smooth muscles and elastic tissue and a larger lumen.
What is the significance of the thick wall of arteries?
They allow the arteries to withstand high blood pressure due to the pumping action of the heart.
How does the thick layer of elastic tissues in arteries maintain a continuous blood flow?
The thick layer of elastic tissue of the arteries allows them to distend and recoil. When the heart relaxes, the arteries recoil due to the elasticity of their walls, which causes the blood to flow forwards.
How is the amount of blood flow to different parts of the body regulated?
In the arterioles, the thick layer of muscles contract or relax to change the size of the lumen. This regulates the amount of blood flow to different parts of the body.
What is the significance of the large lumen of veins?
They reduce the resistance to the blood flow inside the veins.
How is a continuous forward blood flow maintained in the veins?
Valves are present in veins to prevent the backflow of blood.
The force for blood flow in veins is mainly provided by the contraction of skeletal muscles lying next to the veins. When the muscles contract, the veins are squeezed and the blood is forced to flow towards the heart.
Compare the locations of arteries and veins.
Arteries are located deep inside the body while veins are located closer towards the body surface.
Compare the directions of blood flow of arteries and veins.
Arteries carry blood away from the heart while veins carry blood towards the heart.
Compare the sources of the force for blood flow in arteries and veins.
The force for blood flow in arteries is provided by the pumping action of the heart. The force for blood flow in veins is provided by the contraction of skeletal muscles that squeeze the vein.
Compare the blood pressure in arteries and veins.
The blood pressure in arteries is higher due to the pumping action of the heart. The blood pressure in veins is lower, since the blood has flowed for a long distance and has overcome great resistance of the walls of blood vessels.
In which artery / arteries is deoxygenated blood transported?
Pulmonary artery, umbilical artery
In which vein / veins is oxygenated blood transported?
Pulmonary vein, umbilical vein
What are the features of capillaries?
Their lumen is only slightly larger than the diameter of a red blood cell. The capillary wall is made up of one-cell thick endothelium, which is differentially permeable. There is no muscle layer in the capillary walls.
List 3 ways in which capillaries are adapted for the exchange of materials between the blood and body cells?
- The capillary bed is highly branched, which provides a large surface area for rapid exchange of materials between the blood and body cells.
- Each artery eventually branches into a very large number of capillaries. The total cross-sectional area is much greater in the capillary beds than in any other part of the circulatory system. Blood flows slowly in the capillaries, which allows a longer time for exchange of materials between the blood and body cells.
- The one-cell thick capillary wall provides a short distance for the rapid diffusion of materials between the blood and body cells.
What is blood pressure?
Blood pressure is the force exerted on the wall of the blood vessel by the blood flow per unit area.
Explain the blood pressure in arteries and arterioles.
Blood pressure is high due to the pumping action of the heart. It also changes periodically as the heart contracts and relaxes.
Explain the blood pressure in capillaries.
The blood pressure in capillaries drops significantly compared to that in the arteries and arterioles. The small diameter of the capillaries results in a high resistance to blood flow, so the blood pressure has a significant drop.
Explain the blood pressure in veins and venules.
The blood has overcome great resistance of the blood vessel walls after travelling a long distance from the heart. The blood pressure drops to nearly zero.
Explain the rate of blood flow in arteries and arterioles.
The rate of blood flow in the arteries is high due to the pumping action of the heart. When the arteries branch into arterioles, the total cross-sectional area of the arterioles increases, so the flow rate drops.
Explain the rate of blood flow in capillaries.
The total cross-sectional area of capillaries is the greatest in the circulatory system. The rate of blood flow drops to nearly zero, providing more time for the exchange of materials between the blood and body cells.
Explain the rate of blood flow in veins and venules.
The force from the pumping heart can no longer drive blood forwards. The rate of blood flow increases due to the contraction of skeletal muscles lying next to the veins, and the decrease in total cross-sectional area of veins and venules compared to capillaries.
