Endocrine

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Question 1

Name two hormones that cause an increase in blood sugar levels. (2)

Glucagon and adrenalin

Name two hormones that are secreted by the anterior lobe of the pituitary gland. (2)

Human growth hormone, TSH, LH, FSH, prolactin.

State four functions of adrenalin. (4)

Increases heart beat and blood pressure.

Increases rate and depth of breathing.

Converts stored glycogen in liver to glucose.

Constricts blood vessels in skin.

Increases muscle tension.

Decreases peristalsis & blood flow to intestine.

Dilates pupils.

Dilates bronchioli.

In order to stabilize the condition of an injured person after an accident, he was injected intravenously with adrenalin. The graph below illustrates the changes that occurred in the pulse rate of this person after the injection was administered.

Study the graph and answer the questions that follow:

Question 2

When is adrenalin produced in the body? (1)

When the body experiences stress.

State the pulse rate before the injection. (1)

60 beats per minute.

What is the pulse rate ONE minute after the injection was given? (2)

Approximately 97 beats per minute.

Explain the significance of an increase in the pulse rate of a person. (2)

More blood flows to vital organs.

How many minutes after the injection was given was the patient’s pulse rate 80 beats per minute? (2)

Half a minute and at three minutes.

Mention a possible danger of injecting a healthy person with adrenalin after he has eaten a large meal. (2)

Adrenalin will cause less blood to flow to the stomach and intestines. This could result in the person experiencing abdominal cramps.

Question 3

Where is insulin produced? Describe how insulin causes the blood glucose level to decrease. (5)

B-cells of Islets of Langerhans in the pancreas.

Insulin converts glucose to glycogen, which is stored in the liver and muscles.

Insulin also promotes the absorption of glucose into body cells.

Insulin causes excess glucose to be converted to fats and stored.

Suggest one reason why insulin is injected, not taken orally (by mouth). (3)

Insulin is a protein. Proteins are digested / broken down in the stomach. Hence insulin is not taken in orally.

Diabetics usually inject insulin into fatty tissue rather than directly into the bloodstream. Explain why this is done. (3)

Insulin injected into fat will be released slowly into the blood. Hence the person’s glucose levels will be controlled over a few hours. If injected into the blood, the person’s glucose level will drop drastically.

State ONE advantage and ONE disadvantage of nasal sprays instead of injections to administer insulin. (3)

Advantage: Painless

Disadvantage: Can never be sure of exact dosage. / Degree of discomfort. / Expensive.

During strenuous exercise the blood glucose level begins to rapidly decrease. Describe how the body reacts to increase the blood glucose level to normal. (4)

Pancreas will secret hormone glucagon which will convert stored glycogen into glucose. Hence glucose level will return to normal level.

Two patients, one of whom is diabetic, were told to fast overnight and then had their blood glucose levels monitored in a clinic. Both were given glucose solution to drink 30 minutes after the start of the investigation. Examine the changes in their glucose levels over 2 hours:

Study the graph and answer the questions that follow:

Question 4

What is the blood glucose concentration (g/cm³) of the person with diabetes mellitus at 90 minutes? (1)

0,25 g/cm³

How many minutes after the ingestion of glucose did the glucose concentration reach its highest level in the normal person? (1)

15 minutes

Describe TWO differences in the pattern of the blood glucose concentration for the person with diabetes mellitus and a normal person. (4)

Blood glucose level of a person with diabetes is higher than that of a normal person at all times.

There is a greater increase in blood glucose level of a person with diabetes mellitus after ingestion of glucose compared to the normal person.

Takes longer for person with diabetes mellitus to stabilise compared to a normal person

(Any 2)

Explain the reason for the differences mentioned in question above. (2)

Because the person with diabetes mellitus does not produce insulin / is insulin resistant.

Name TWO hormones that have the opposite effect to that of insulin. (2)

Glucagon and adrenalin

Set 1

Set 2

Set 1

Set 2

Study the flow diagram below of a homeostatic mechanism used to regulate the concentration of salts in the human body.

Question 5

Define homeostasis. (2)

The process by which the human body is able to maintain a constant internal environment

Name organ A (1)

Hypothalamus

Name gland B (1)

Adrenal gland

Name hormone C (1)

Aldosterone

Describe the response by the effector at D. (2)

Walls of renal tubules become more permeable allowing for a greater re-absorption of sodium ions from the filtrate/into the blood capillaries.

Questions source: DBE (Authorisation 11798)

- Greg Gopaul -