Chapter 5.2 Regulation of Blood Sugar ✓

Question 1

What form is sugar in the blood?

Answer 1

Glucose

Question 2

What does ‘blood sugar refer to?

Answer 2

Refers to the amount of glucose in the blood

Question 3

Why do all cells need a constant source of glucose?

Answer 3

Because it is a source of energy for all the cells’ activities e.g movement, reproduction, synthesising molecules, active transport etc.

Question 4

What is the formula of cellular respiration?

Answer 4

Glucose + Oxygen -> Carbon dioxide + Water + Energy

Question 5

What food contributes to the body’s source of glucose and how?

Answer 5

Carbohydrates. They are broken down into glucose during digestion and the absorbed into the blood through the walls of the small intestine.

Question 6

What form is glucose stored as?

Answer 6

Glycogen (it is a molecule made of long chains of glucose)

Question 7

Where does glucose get stored in and how many grams can glucose be stored in the body?

Answer 7

-500g of glycogen can be stored in the body
-About 100g stored in the liver and the rest in skeletal muscle cells

Question 8

Write a summary/diagram of glucose-glycogen conversion

Answer 8

Glucose -> Glycogen
-Blood glucose level high such as after a meal

Glycogen -> Glucose
Blood glucose level low such as during exercise

Question 9

Where is the liver located?

Answer 9

Located in the upper abdominal cavity just below the diaphragm

Question 10

What is the role of the liver in controlling the blood sugar concentration?

Answer 10

The liver is able to convert glucose into glycogen for storage or glycogen to glucose for release into the blood

Question 11

Which blood vessel supplies most of the liver’s blood and from which organs does it receive this blood?

Answer 11

The hepatic portal vein supplies the liver with blood and the organs it receives it from are the:
-Stomach
-Spleen
-Pancreas
-Small and large intestines

Thus the liver has the first chance to absorb the nutrients from digested food.

Question 12

What happens to the carbohydrates after a meal, and where are they absorbed in the digestive system?

Answer 12

After a meal, carbohydrates are absorbed as glucose in the blood capillaries of the villi in the small intestine

Question 13

What is the role of the hepatic portal vein in glucose transport after absorption?

Answer 13

It carries glucose from the small intestine to the liver

Question 14

What are the possible fates of glucose once it reaches the liver?

Answer 14

It can be:
-Used by the liver for energy
-Stored as glycogen in the liver and muscles
-Remain in the bloodstream for body cells to use
-Converted to fat for long-term storage if in excess

Question 15

Define glycogenesis

Answer 15

The process whereby glucose molecules are chemically combined in long chains to form glycogen molecules

Question 16

What hormone stimulates glycogenesis and where is it secreted from?

Answer 16

Insulin, secreted from the pancreas, stimulates the process of glycogenesis

Question 17

Can glycogen be used directly by cells?

Answer 17

No it must convert back to glucose

Question 18

Define glycogenolysis

Answer 18

The process of converting glycogen back to glucose

Question 19

What stimulates the process of glycogenolysis and where is it secreted?

Answer 19

Glucagon, secreted from the pancreas, stimulates the process of glycogenolysis
-It occurs between meals

Question 20

Define gluconeogenesis

Answer 20

Conversion of fats or proteins into glucose

Question 21

Define Islets of Langerhans

Answer 21

Clusters of endocrine cells in the pancreas; secrete the hormones insulin and glucagon

Question 22

What are the two different types of cells in the Islets of Langerhans

Answer 22

Alpha cells
Beta cells

Question 23

What do alpha cells secrete?

Answer 23

Glucagon

Question 24

What do beta cells secrete?

Answer 24

Insulin

Question 25

How does insulin decrease blood glucose levels?

Answer 25

It does so by: -accelerating the transport of glucose from the blood into body cells, especially those of the skeletal muscles -accelerating the conversion of glucose into glycogen in the liver and skeletal muscles (glycogenesis) -stimulating the conversion of glucose into protein (protein synthesis) -stimulating the conversion of glucose into fat (lipids) in adipose tissue, or fat storage tissues; a process called lipogenesis

Question 26

Define lipogenesis

Answer 26

The production of lipids (fats)

Question 27

How does glucagon cause an increase in blood glucose levels?

Answer 27

It does so by: -stimulating glycogenolysis, the conversion of glycogen into glucose, in the liver -stimulating gluconeogenesis, the production of new sugar molecules from fats (lipids) and amino acids, in the liver. This involves the breakdown of lipids, lipolysis -having a mild stimulating effect on protein breakdown

Question 28

Define lipolysis

Answer 28

The breakdown of lipids (fats) in the body

Question 29

What two parts compose the adrenal gland?

Answer 29

The medulla (inner part) and cortex (outerpart)

Question 30

What gland secretes cortisol?

Answer 30

The cortex

Question 31

What hormone stimulates the adrenal cortex to release its hormone?

Answer 31

Adrenocorticotropic hormone (ACTH) from the anterior lobe of the pituitary gland

Question 32

What type of hormones does the adrenal cortex produce?

Answer 32

Glucocorticoids, mainly cortisol

Question 33

What are the functions of cortisol (a glucocorticoid)?

Answer 33

-Stimulates the conversion of glycogen into glucose in the liver -Stimulates protein breakdown in muscles and conversion of amino acids into glucose -Promotes the mobilisation of fatty acids from fat tissue for energy

Question 34

What hormones are produced by the adrenal medulla?

Answer 34

Adrenaline and noradrenaline

Question 35

How do adrenaline and noradrenaline affect blood glucose levels?

Answer 35

The stimulates the breakdown of glycogen in the liver and release glucose into the blood

Question 36

How does cortisol help regulate blood glucose?

Answer 36

By ensuring enough energy is available to cells through glucose production from glycogen, proteins and fats

Question 37

List the organs that play key roles in glucose homeostasis?

Answer 37

-Liver -Pancreas -Adrenal glands

Question 38

Describe what happens to glucose from ingestion to it passing through the liver.

Answer 38

-Carbohydrates are ingestion and begin to be broken down in the mouth by salivary amylase -In the small intestine, digestive enzymes break down carbohydrates down into glucose -Glucose is absorbed through the walls of the small intestine into the blood stream -Glucose travels through the hepatic protein vein to the liver -In the liver glucose is: -Used for immediate energy -Stored as glycogen if blood glucose levels are high (glycogenesis) -Or stored into the blood if glucose is needed

Question 39

Blood glucose levels increase after eating carbohydrates a) What is the key hormone that will initially be released? b) What organ produces this hormone? c) What cells within the organ produce this hormone d) What responses does the hormone lead to?

Answer 39

a) Insulin b) Pancreas c) Beta cells in the islets of Langerhans d) Insulin causes: -Glucose uptake by cells -Glycogenesis -Lowering of blood glucose leve;s

Question 40

Describe the role of the adrenal glands in controlling the level of glucose in the blood

Answer 40

Adrenal cortex releases cortisol which: -Stimulates gluconeogenesis -Reduces glucose uptake in tissues -Mobilises fats and proteins for energy Adrenal medulla releases adrenaline which: -Stimulates glycogenolysis -Inhibits insulin secretion Both hormones work to increase blood glucose levels during stress or fasting

Question 41

What is the word equation for cellular respiration and how does it relate to glucose homeostasis?

Answer 41

Glucose + Oxygen -> Carbon dioxide + Water + Energy (ATP) Relation to glucose homeostasis -Energy production: Cellular respiration converts glucose into ATP, providing energy for cellular functions -Blood glucose regulation: After carbohydrate intake, blood glucose levels rise. Insulin facilitates glucose uptake by cells, where its used in cellular respiration, thereby lowering blood glucose levels -Response to Low glucose: When blood glucose is low, the body can produce glucose through gluconegenesis or break down glycogen stores, ensuring a continuous supply of glucose for cellular respiration and maintaining energy production

Question 42

Use the Stimulus-Response-Feedback model to summarise how the pancreas response after strenuous activity

Answer 42

-Stimulus: Blood glucose levels drop after exercise due to increased energy use -Receptor: Chemoreceptors (Alpha cells in pancreas) detect low blood glucose levels -Message: Alpha cells release glucagon -Modulator: Pancreas processes the signal and releases glucagon -Message: Glucagon sent into the bloodstream -Effector: Liver receives glucagon -Response: Liver breaks down glycogen, releases glucose into the blood -Feedback: Blood glucose rises, reducing glucagon release; Negative feedback