8.1. The circulatory system
A subsection of Biology, 9700, through 8. Transport in mammals
Listing 10 of 175 questions
The liver receives blood from the hepatic artery and from the hepatic portal vein. The hepatic portal vein transports blood from the digestive system. Hepatocytes are the main cell type of the liver. They have a wide range of functions, including: • the synthesis of triglycerides and plasma proteins • detoxifying waste • energy storage. The hepatic artery branches from the main artery that transports blood from the heart. Name the main artery that transports blood to the hepatic artery. Blood arriving at the liver enters specialised blood vessels known as sinusoids. is a diagram of part of a sinusoid and surrounding hepatocytes. A second type of cell found in the liver, a Kupffer cell, is also shown. Kupffer cells are phagocytic cells of the immune system. sinusoid large gap between endothelial cells Kupffer cell hepatocyte Suggest one advantage of having large gaps between the endothelial cells of the sinusoid, as shown in . In addition to removing bacteria present in the blood inside the sinusoid, Kupffer cells are also able to remove old or damaged red blood cells. Describe the mode of action of a Kupffer cell in removing and breaking down a damaged red blood cell. is a transmission electron micrograph of part of a hepatocyte showing some cell structures. The peroxisome shown in is a spherical organelle bound by a single membrane. It carries out a variety of enzyme-catalysed metabolic reactions, including detoxification. Some of these reactions require oxygen. peroxisome glycogen granules lipid droplet Describe the evidence visible in , apart from the presence of a peroxisome, that indicates some of the functions of a hepatocyte. Add labels to to identify the location of any cell structures, if not already labelled, that are part of your evidence. The mitochondria in are larger than the peroxisome. State one other difference, visible in , between a peroxisome and a mitochondrion. Some of the enzymes used within mitochondria can be synthesised by the organelle. Peroxisomes cannot synthesise any of the enzymes that they contain. Suggest why a mitochondrion can synthesise enzymes, but a peroxisome cannot synthesise enzymes. One of the enzymes present in peroxisomes is catalase. This enzyme catalyses the breakdown of hydrogen peroxide to harmless products. Suggest why it is useful to the cell for this reaction to take place within peroxisomes.
9700_w23_qp_22
THEORY
2023
Paper 2, Variant 2
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In the mammalian circulatory system, red blood cells travel through different types of blood vessel as they pass from the heart to respiring tissues and back to the heart. shows the types of blood vessels through which red blood cells travel in the circulatory system. heart arteries capillaries veins Complete by writing the names of the missing types of blood vessels through which red blood cells travel. Water is the main component of blood. It has an important role in the transport of substances around the body. shows the ionic compound sodium chloride dissolving in water. Cl – Cl – Na+ Cl – Na+ Cl – Na+ Cl – Na+ Cl – Na+ Cl – Cl – Cl – Na+ Na+ Cl – Na+ Cl – Na+ Cl – Cl – Cl – Na+ Na+ Cl – Na+ Cl – Cl – Cl – H O diagram not to scale With reference to , explain how water acts as a solvent for sodium chloride. shows a Galapagos penguin, Spheniscus mendiculus, swimming in the water. Penguins are birds that live on land but spend a lot of time swimming underwater hunting for food. Penguins can remain underwater for up to twenty minutes. During this time they do not breathe but their tissues continue to respire. Haemoglobin in the red blood cells of penguins has a higher affinity for oxygen than haemoglobin in other birds that do not swim underwater. shows the oxygen dissociation curve for a bird that does not swim underwater. Draw a line on to suggest the position of the oxygen dissociation curve for penguin haemoglobin. Penguin haemoglobin is very sensitive to a decrease in pH caused by an increase in the carbon dioxide concentration in the blood. Explain how a decrease in pH affects penguin haemoglobin, and suggest how this helps the penguin to swim underwater for a long time. The heart rate of a penguin decreases while it is swimming underwater. Heart rate is regulated by a group of specialised cells in the wall of the right atrium. The activity of these cells is modified by nerve impulses. Name the group of specialised cells in the wall of the right atrium that regulates heart rate.
9700_w24_qp_21
THEORY
2024
Paper 2, Variant 1
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Complete Table 5.1 by numbering each event to show the sequence occurring in the initiation and control of one heart beat. Use 1 as the first event in the sequence. Table 5.1 event sequence impulses pass down septum through conducting fibres known as the bundle of His atrioventricular node sends out impulses impulses travel across atrial walls impulses reach base of ventricles (apex of heart) impulses pass up through Purkyne fibres in ventricle walls sinoatrial node sends out impulses Explain the circumstances that cause the closing of the semi-lunar valves during the cardiac cycle. At the arterial end of a capillary bed in muscle tissue, the hydrostatic pressure is high enough to cause the formation of tissue fluid. Explain the differences between the composition of blood and the composition of tissue fluid at the arterial end of a capillary bed.
9700_w14_qp_22
THEORY
2014
Paper 2, Variant 2
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Questions Discovered
175