The heart & circulation

The diagram shows the human circulatory system, with blood vessels labelled A to N.

The table lists some of the blood vessels in the human circulatory system. Complete the table by giving the correct letter for each blood vessel. The first one has been done for you.

Use letters from the diagram to answer these questions.

Which blood vessel contains blood with the highest concentration of oxygen?

Which blood vessel carries blood at the highest pressure?

Which blood vessel is an artery that carries blood with a high concentration of carbon dioxide?

Scientists have developed a synthetic material that can be used to replace damaged arteries. State two properties that this synthetic material should have so that it can act as a suitable replacement for damaged arteries.

Blood is circulated through the body in blood vessels.

The table lists some blood vessels. Complete the table by naming an organ supplied with blood by each blood vessel.

A student uses this apparatus to compare the strength of arteries and veins.

This is the student’s method.

• cut a cross-section from an artery and from a vein to make rings of tissue

• hang a ring of tissue from the hook

• add 10 g masses to the ring of tissue one at a time

• record the total mass at which the ring of tissue breaks

• repeat the method with the other ring of tissue

Explain the results that you would expect the student to obtain.

Give one way that the student could modify his investigation to improve the reliability of his results.

Give one way that the student could modify his investigation to improve the accuracy of his results.

The diagram shows the structure of the human heart.

Explain how you know that X is the right side of the heart.

Give the name of chamber A.

On the diagram, label the pulmonary artery.

Explain the difference in the structure of the walls of chamber A and chamber B.

Give the name of structure C.

Describe the function of structure C.

Sometimes a baby is born with a hole between chambers A and B. Suggest the effects that this condition may have on the baby.

A student wants to investigate the effect of exercise on heart rate.

Describe how the student could measure heart rate.

Explain how the student could ensure that the results obtained would allow a valid comparison to be made.

Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. Glucose control Many years ago some scientists wanted to find out more about the role of the pancreas in digestion. They used surgery to remove the pancreas from dogs to see what would happen. During this investigation a laboratory assistant noticed that flies collected around the dogs’ urine. This urine was later found to contain large amounts of glucose. Urine from dogs with a pancreas does not contain glucose. Another scientist used string to tie a knot around the pancreatic duct of rabbits, which closed the duct. This meant that no pancreatic enzymes could reach the small intestine. It was noticed that when this was done, the cells in the pancreas that made enzymes died, but no glucose appeared in the rabbit urine. Other scientists made pancreas extract by crushing up a pancreas in water. They injected this extract into dogs that had their pancreas removed. They found that the blood glucose level in these dogs was much reduced. These investigations and observations suggest that the pancreas has two different functions. Some of the cells produce enzymes needed for digestion. Other parts of the pancreas are not involved in digestion but are important in controlling blood glucose levels. We now know that pancreas extract contains two hormones involved with the regulation of blood glucose levels – insulin and glucagon. High blood glucose levels are detected by the pancreas. This stimulates the pancreas to release insulin. The role of insulin is to lower blood glucose levels. The insulin is released from specialised cells directly into the blood. The insulin travels in the blood to target cells that are in the liver and in large muscles. Insulin causes these cells to absorb glucose and use it to make an insoluble storage carbohydrate called glycogen. The second hormone called glucagon is released by different cells in the pancreas when the blood glucose level falls too low. Glucagon causes liver and muscle cells to change glycogen into soluble glucose.

Explain what is meant by the term digestion (line 2).

Explain why dogs that had their pancreas removed produced urine that contained glucose (lines 4 and 5).

Name two enzymes produced by cells in the pancreas (lines 8 and 9).

Suggest why rabbits that have had their pancreatic duct tied can still regulate their blood glucose levels (lines 10 and 11).

The scientists who injected pancreas extract into dogs should have carried out a control experiment (line 13). Explain the control experiment they should have carried out.

Name the blood vessel that transports hormones into the liver (line 24).

Suggest one advantage of storing glycogen in cells rather than storing glucose in cells (lines 25 and 26).

A number of different substances and structures are involved in the control of blood glucose.

Describe the stimulus.

Name the structure that acts as a receptor.

Name a structure that acts as an effector.

Describe the response.

The diagram shows a section through a human heart.

The blood in vessel X is transported to an organ.

Name the organ.

State two changes to the blood in this organ.

What is the function of the part labelled Y?

The diagram shows the contraction and relaxation of the atria and ventricles during several heartbeats. Each square represents a time of 0.1 second.

For how long do the ventricles contract during one heartbeat?

How many heartbeats does the diagram show?

Use the diagram to calculate the heart rate of this person in beats per minute. Show your working.

_........ beats per minute

The diagram shows a mammal heart with glass tubes, X and Y, securely attached to the vena cava and the pulmonary artery. Water was poured into tube X, and rose up tube Y until both tubes were filled to the level shown.

When water was poured into tube X, two chambers in the heart were filled with water. Name these two chambers.

The ventricles were squeezed once by hand.

Suggest what would happen to the level of water in tube X and in tube Y when the ventricles were squeezed.

Explain why no water came out of the aorta when the ventricles were squeezed.