glucose regulation

Question 1

what is blood sugar?

Answer 1

amount of glucose in the blood

Question 2

how is energy released from glucose?

Answer 2

cellular respiration

Question 3

what is the equation for cellular respiration?

Answer 3

glucose + oxygen&raquo_space; carbon dioxide + water + energy

Question 4

what are the sources of blood glucose?

Answer 4

diet = glucose released from the breakdown of other carbs
breakdown of glycogen = broken down in the liver or muscles cells
gluconeogenesis = production of new glucose molecules from non-carbohydrates

Question 5

what happens when there is a rise in glucose levels?

Answer 5

= hyperglycemia

- stimulates insulin secretion

Question 6

what happens when there is a decrease in glucose levels?

Answer 6

= hypoglycemia

- inhibits insulin secretion

Question 7

what factors influence our blood glucose levels?

Answer 7

• eating takes place + types of food eaten
• the amount of physical + mental activity
• the presence of insulin, glucagon + adrenaline

Question 8

what is glycogen?

Answer 8

• stored glucose
• a molecule made of long chains of glucose molecules
• 500g stored

Question 9

what is the function of the liver in glucose regulation?

Answer 9

= convert glucose into glycogen for storage or glycogen to glucose for release into the blood

Question 10

where is the liver’s blood supply?

Answer 10

• mainly through the hepatic portal vein
• brings blood directly from the stomach, spleen, pancreas, and small + large intestines
  = has the first chance to absorb nutrients from digested food

Question 11

what can happen to glucose in the liver?

Answer 11

• be removed from the blood by liver to provide energy for liver functioning
• be removed by the liver and be converted into glycogen for storage
• continue to circulate in the blood, available for body cells to absorb and use as a source of energy
• be converted into fat for long-term storage if it is in excess of that required to maintain both normal blood sugar and tissue glycogen levels

Question 12

define glycogenesis

Answer 12

= formation of glycogen from other carbohydrates, especially glucose
- stimulated by insulin

Question 13

the function of glycogen?

Answer 13

• cannot be used by cells = must be converted into glucose or simple sugars
• maintain blood sugar levels and supply energy for liver activity
• in muscle cells = provides glucose required for muscle activity

Question 14

what happens when the level of glucose in the blood drops below normal?

Answer 14

• glycogen stored in the liver and muscle cells can be broken down into glucose

Question 15

define glycogenolysis

Answer 15

= breakdown of glycogen to glucose

- stimulated by glucagon

Question 16

define gluconeogenesis

Answer 16

creating new glucose from fats and proteins

Question 17

define lipogenesis

Answer 17

conversion of glucose into fats

Question 18

define lipolysis

Answer 18

breakdown of lipids

Question 19

what and where are the islets of langerhans?

Answer 19

= clusters of hormone-secreting cells

- located in the pancreas

Question 20

what are the two cells in the islets?

Answer 20

• alpha cells = secrete glucagon

- beta cells = secrete insulin

Question 21

role of insulin?

Answer 21

= decrease blood glucose levels

Question 22

how does insulin decrease blood glucose levels?

Answer 22

• enables entry of glucose into cells
• promotes the conversion of glucose into glycogen in the liver and muscles
• promotes fat storage
• promotes protein synthesis

Question 23

role of glucagon?

Answer 23

= increase blood glucose levels

Question 24

how does glucagon increase blood glucose levels?

Answer 24

• converts liver glycogen into glucose

- promotes gluconeogenesis

Question 25

describe adrenaline

Answer 25

• released by the adrenal medulla in times of danger + stress
• inactivates enzymes which synthesizes glycogen from glucose

Question 26

what are the two parts of the adrenal gland?

Answer 26

• medulla = inner part

- cortex = outter part

Question 27

describe the adrenal cortex

Answer 27

• outer part
• secretes cortisol
• stimulated by adrenocorticotropic hormone (ACTH)

Question 28

describe the functions of cortisol

Answer 28

• stimulate protein breakdown in muscles
• stimulate the conversion of amino acids into glucose in the liver
• stimulates glycogenolysis (glycogen > glucose)

Question 29

describe the adrenal medulla

Answer 29

• inner part

- synthesises adrenaline + noradrenaline

Question 30

what are the functions of adrenaline?

Answer 30

• increase the blood glucose level

- stimulate the breakdown of glucose in liver

Question 31

describe the high blood glucose feedback loop

Answer 31

stimulus = high glucose levels in the blood
receptor = chemoreceptors in islets of Langerhans beta cells
modulator = B cells in islets of Langerhans produce and secrete insulin into the bloodstream in response to high blood glucose levels
effector = liver, all cells, adipose tissue
response = liver takes up glucose from the blood and converts it into glycogen in the process called glycogenesis 
feedback = negative feedback. Response decreases blood glucose levels

Question 32

feedback loop for low blood glucose

Answer 32

stimulus = low blood glucose 
receptor = chemoreceptors in the islets of langerhans alpha cells
modulator = alpha cells release and make glucagon
effector = liver + adipose tissue 
response = gluconeogensis 
feedback = negative resulting in an increase in blood glucose levels