Hormones: Maintaining Blood Homeostasis (AQA GCSE Biology)

Higher Tier Only

Both the liver and pancreas are involved in maintaining blood glucose concentration within a narrow range.

The blood glucose concentration of an athlete was monitored over the course of a day. One hour after the athlete has eaten a meal, their blood glucose concentration rises.

Explain why it is important that negative feedback brings a raised blood glucose concentration back down.

Figure 1 shows some of the blood vessels associated with the liver.

The two veins associated with the liver are:

• The portal vein, delivering blood from the small intestine to the liver

• The hepatic vein, which connects the liver to the vena cava.

The concentration of glucose can be measured from samples of blood taken from the hepatic vein and the portal vein.

Suggest and explain how the concentration of glucose in these two blood vessels would differ 1 hour after a meal.

Higher Tier Only

Three hours after having eaten, the athlete runs on a treadmill for one hour.

The athlete’s blood glucose concentration decreases as he runs.

Describe how the body responds when the blood concentration begins to decrease.

Individuals with diabetes cannot control their blood glucose levels. There are two types of diabetes: Type 1 and Type 2.

Compare and contrast the causes of, and treatments for, each type of diabetes.

A blood test can be used to see how the body responds to glucose. The blood glucose concentration can be measured before and after drinking a glucose drink.

It is important that patients do not eat or drink anything other than water before the blood test.

Suggest why.

Figure 1 shows the results of a blood glucose tolerance test for two people (A and B).

Figure 1

Which patient has diabetes?

Justify your answer.

Look at the data in Table 1.

Table 1

Calculate the percentage (%) of the population of the USA estimated to have diabetes.

You should include both diagnosed and undiagnosed people in your calculation.

Give your answer to 2 significant figures.

Many functions of the human body are controlled by chemicals called hormones.

What is a hormone?

The kidney is responsible for maintaining the water balance of the body.

Describe how hormones and kidneys regulate the water balance of the blood.

The kidneys filter the blood to produce urine, a mixture of minerals ions, urea and water. The pores of the kidney have a diameter of about 6 nanometres.

Table 1 shows the size of a number of molecules dissolved in blood plasma.

Table 1

Identify which substance from the table in Table 1 would not be found in the urine of a healthy person.

Suggest what the substance you identified in question 3(c) is and explain why it is not found in the urine of a healthy person.

Another substance not found in the urine of a healthy individual is substance M.

Suggest an explanation for this.

The endocrine system, in combination with the nervous system, play a key role in regulation of many internal conditions in the human body.

Describe how the detection of a stimulus by a receptor of the nervous system can result in stimulation of the endocrine system. 

(i) Identify the gland referred to as the 'master gland' in the endocrine system.

[1]

(ii) Suggest why this gland is referred to as the 'master gland'.

[1]

Higher Tier Only

An investigation was carried out into the effect of a high protein diet on excretion in terms of synthesis of urea and production of urine.

The results can be seen in the table 1.

Table 1

Explain why an increase in dietary protein may result in an increase in synthesis of urea in the human body.

Suggest the link between the synthesis of urea and the volume of urine production shown in table 1.

Higher Tier Only

Diabetes insipidus is a disease which results in the inability to produce enough of the hormone ADH.

In a medical study, the ADH levels in the blood of 8 people were measured.

Four of the people A, B, C and D do not have diabetes insipidus.

The other four people E, F, G and H do suffer from the disease.

The results are shown in Table 1.

Table 1

Calculate the mean ADH level in the people without diabetes insipidus.

Higher Tier Only

Suggest why there is a wide range of ADH levels in individuals without diabetes insipidus.

Higher Tier Only

Explain why diabetes insipidus is likely to result in large volumes of urine production.

Table 1 shows some features that can be found in the endocrine system. 

Table 1

Complete Table 1 by listing descriptions for each feature of the endocrine system.

Androgenic anabolic steroids are synthetic derivatives of the male hormone testosterone.

They have approved medical uses in male patients with disorders of the testicles or pituitary gland.

Some of the effects of these substances are shown below in Figure 1.

Figure 1

Suggest why androgenic anabolic steroids are a banned substance in sport.

Pancreatic cancer is a lethal disease characterised by progressive weight loss, fatigue and a sudden-change in previously well-controlled blood sugar levels.

Suggest what causes these symptoms.

The hypothalamus is the section of the brain that links the nervous system and the endocrine system in order to maintain homeostasis.

Suggest which gland in the endocrine system the hypothalamus targets?

Higher Tier Only

Pituitary tumours are usually abnormal, benign growths in the pituitary gland, that can impact important surrounding structures, such as nerves or blood vessels. Consequently, patients suffering from a pituitary tumour usually have the tumour and a large part of their pituitary gland removed, which can impact the amount of hormones produced.

Suggest the side effects of female patient, after having a pituitary tumour removed.

Some individuals suffer from starvation even though they eat sufficient amounts of food.

Identify which condition of A - D could explain this.

Higher Tier Only

When participating in intense physical exercise a person's overall rate of metabolism increases.

Which hormones are released to allow the blood glucose levels to meet the increased metabolic demands of exercise?

Higher Tier Only

Figure 2 shows the blood glucose levels of a healthy individual.

Explain the events that most likely occur at points A to D.

Figure 2

The insulin receptor (INSR), is a transmembrane receptor that is activated when insulin binds to it. The binding of insulin triggers a signalling pathway that activates glucose transporters in the cell membrane. 

Some people suffer from a mutation in the INSR gene. 

Suggest the effect of such a mutation. 

A scientist was interested in finding out how much water was lost from the human body on a particular day.

They measured the volume of fluid consumed and the volume of urine excreted.

Explain why measuring the volume of urine excreted would not be an accurate assessment of water lost.

A small number of patients with diabetes are given a pancreas transplant.

Out of these patients, only about 15% suffer from type II diabetes.

Explain why pancreas transplants are not often used for the treatment of type II diabetes.

Glucose tolerance tests can be used to assess if a patient has diabetes. During the test, a patient (who has fasted for eight hours) drinks a sugary solution and the glucose concentration of the blood is measured at regular intervals.

Figure 2 shows the results of a blood glucose tolerance test for a patient with diabetes (patient A).

Figure 2

Patient B who does not suffer from diabetes, undertook the same glucose tolerance test. The glucose concentration in their blood prior to drinking the sugary solution was 5 mmol / L .

Draw a curve on the graph in Figure 2 to show the results you would predict for patient B.

In the glucose tolerance test, diabetes is diagnosed if the concentration of glucose in the blood is higher than 7 mmol / L from at least two different tests.

Explain why the results may sometimes be inaccurate. 

Table 2 shows the composition of urine in a healthy individual.

Table 2

Explain what the missing values in Table 2 would most likely be.

Higher Tier Only

Following the consumption of drinks containing caffeine, urine production increases when compared to consuming the same volume of a non-caffeinated drink.

Suggest a biological mechanism for why this may happen.

Explain how a dialysis machine filters blood.

Explain why the majority of doctors consider kidney transplants to be a preferable solution compared to dialysis, for patients with kidney failure.

Table 3 shows the number of single organ transplants that were performed in the UK in 2018.

Table 3

Suggest why kidney transplants were the most frequent organ transplant.