6.4.3
Controlling Blood Glucose Concentration
Insulin
Insulin
When blood glucose concentration increases above the optimum concentration (90mg 100cm−3), insulin returns the level to normal through negative feedback. The steps involved are:


1) Detection by beta cells
1) Detection by beta cells
- High blood glucose concentration is detected by the beta (β) cells in the pancreas.
- Beta cells are located in the islets of Langerhans.


2) Secretion of insulin
2) Secretion of insulin
- Beta cells respond to high blood glucose concentration by secreting a hormone called insulin into the blood.
- Insulin travels in the blood to the liver and muscle cells.


3) Binding to muscle cells
3) Binding to muscle cells
- Insulin binds to receptors on the muscle cell membranes.
- The muscle cells insert more glucose channel proteins in the cell membrane. This causes:
- The rate of uptake of glucose by muscle cells to increase.
- The rate of respiration in the muscle cells to increase.


4) Glycogenesis
4) Glycogenesis
- Insulin binds to receptors on the liver cell membranes.
- The liver cells produce enzymes that convert glucose to glycogen.
- Glycogen is stored in the liver cells' cytoplasm.
- This process is called glycogenesis.


Importance of insulin
Importance of insulin
- The role of insulin in lowering blood glucose concentration is important for maintaining an optimum blood water potential.
- If blood glucose levels were not reduced by insulin, the blood water potential would decrease.
- Water in the cells in the body would diffuse out, causing the cells to shrink and die.
Glucagon
Glucagon
When blood glucose concentration decreases below the optimum concentration (90mg 100cm−3), glucagon, like insulin, returns the level to normal through negative feedback. The steps involved are:


1) Detection by alpha cells
1) Detection by alpha cells
- Low blood glucose concentration is detected by the alpha (α) cells in the pancreas.
- Alpha cells are located in the islets of Langerhans.


2) Secretion of glucagon
2) Secretion of glucagon
- Alpha cells respond to low blood glucose concentration by secreting a hormone called glucagon into the blood.
- Glucagon travels in the blood to the liver cells.


3) Glycogenolysis
3) Glycogenolysis
- Glucagon binds to receptors on the liver cell membranes.
- The liver cells produce enzymes that convert glycogen to glucose.
- This process is called glycogenolysis.


4) Gluconeogenesis
4) Gluconeogenesis
- Binding of glucagon to liver cell membranes also causes the release of enzymes that form glucose from glycerol and amino acids.
- This process is called gluconeogenesis.


5) Rate of respiration
5) Rate of respiration
- Glucagon also slows the respiration rate in cells.
- Slowing respiration slows the rate at which glucose is used up.


Importance of glucagon
Importance of glucagon
- The role of glucagon in increasing blood glucose concentration is important for survival.
- If blood glucose levels were not increased by glucagon, there would not be enough glucose available for respiration.
- If there is not enough glucose for respiration, there will be no energy available for survival.
Adrenaline
Adrenaline
Adrenaline is a hormone that is secreted in response to low blood glucose concentration. It is also released during exercise and in times of stress. The steps of the adrenaline response are:


1) Secretion of adrenaline
1) Secretion of adrenaline
- Adrenaline is secreted from the adrenal gland in response to low blood glucose concentration, exercise and stress.


2) Binding to liver cells
2) Binding to liver cells
- Adrenaline binds to receptors on the liver cell membrane.
- Adrenaline induces two reactions in the liver cells:
- Activation of glycogenolysis (glycogen → glucose).
- Inhibition of glycogenesis (glucose → glycogen).
- Adrenaline also promotes secretion of glucagon from the pancreas and inhibits secretion of insulin.
1Biological Molecules
1.1Monomers & Polymers
1.2Carbohydrates
1.3Lipids
1.4Proteins
1.4.1The Peptide Chain
1.4.2Investigating Proteins
1.4.3Primary & Secondary Protein Structure
1.4.4Tertiary & Quaternary Protein Structure
1.4.5Enzymes
1.4.6Factors Affecting Enzyme Activity
1.4.7Enzyme-Controlled Reactions
1.4.8End of Topic Test - Lipids & Proteins
1.4.9A-A* (AO3/4) - Enzymes
1.4.10A-A* (AO3/4) - Proteins
1.5Nucleic Acids
1.6ATP
1.7Water
1.8Inorganic Ions
2Cells
2.1Cell Structure
2.2Mitosis & Cancer
2.3Transport Across Cell Membrane
2.4Cell Recognition & the Immune System
3Substance Exchange
3.1Surface Area to Volume Ratio
3.2Gas Exchange
3.3Digestion & Absorption
4Genetic Information & Variation
4.1DNA, Genes & Chromosomes
4.2DNA & Protein Synthesis
4.3Mutations & Meiosis
4.4Genetic Diversity & Adaptation
4.5Species & Taxonomy
4.6Biodiversity Within a Community
4.7Investigating Diversity
5Energy Transfers (A2 only)
5.1Photosynthesis
5.1.1Overview of Photosynthesis
5.1.2Photoionisation of Chlorophyll
5.1.3Production of ATP & Reduced NADP
5.1.4Cyclic Photophosphorylation
5.1.5Light-Independent Reaction
5.1.6A-A* (AO3/4) - Photosynthesis Reactions
5.1.7Limiting Factors
5.1.8Photosynthesis Experiments
5.1.9End of Topic Test - Photosynthesis
5.1.10A-A* (AO3/4) - Photosynthesis
5.2Respiration
5.3Energy & Ecosystems
6Responding to Change (A2 only)
6.1Nervous Communication
6.2Nervous Coordination
6.3Muscle Contraction
6.4Homeostasis
6.4.1Overview of Homeostasis
6.4.2Blood Glucose Concentration
6.4.3Controlling Blood Glucose Concentration
6.4.4End of Topic Test - Blood Glucose
6.4.5Primary & Secondary Messengers
6.4.6Diabetes Mellitus
6.4.7Measuring Glucose Concentration
6.4.8Osmoregulation
6.4.9Controlling Blood Water Potential
6.4.10ADH
6.4.11End of Topic Test - Diabetes & Osmoregulation
6.4.12A-A* (AO3/4) - Homeostasis
7Genetics & Ecosystems (A2 only)
7.1Genetics
7.2Populations
7.3Evolution
7.3.1Variation
7.3.2Natural Selection & Evolution
7.3.3End of Topic Test - Populations & Evolution
7.3.4Types of Selection
7.3.5Types of Selection Summary
7.3.6Overview of Speciation
7.3.7Causes of Speciation
7.3.8Diversity
7.3.9End of Topic Test - Selection & Speciation
7.3.10A-A* (AO3/4) - Populations & Evolution
8The Control of Gene Expression (A2 only)
8.2Gene Expression
8.2.1Stem Cells
8.2.2Stem Cells in Disease
8.2.3End of Topic Test - Mutation & Gene Epression
8.2.4A-A* (AO3/4) - Mutation & Stem Cells
8.2.5Regulating Transcription
8.2.6Epigenetics
8.2.7Epigenetics & Disease
8.2.8Regulating Translation
8.2.9Experimental Data
8.2.10End of Topic Test - Transcription & Translation
8.2.11Tumours
8.2.12Correlations & Causes
8.2.13Prevention & Treatment
8.2.14End of Topic Test - Cancer
8.2.15A-A* (AO3/4) - Gene Expression & Cancer
8.3Genome Projects
Jump to other topics
1Biological Molecules
1.1Monomers & Polymers
1.2Carbohydrates
1.3Lipids
1.4Proteins
1.4.1The Peptide Chain
1.4.2Investigating Proteins
1.4.3Primary & Secondary Protein Structure
1.4.4Tertiary & Quaternary Protein Structure
1.4.5Enzymes
1.4.6Factors Affecting Enzyme Activity
1.4.7Enzyme-Controlled Reactions
1.4.8End of Topic Test - Lipids & Proteins
1.4.9A-A* (AO3/4) - Enzymes
1.4.10A-A* (AO3/4) - Proteins
1.5Nucleic Acids
1.6ATP
1.7Water
1.8Inorganic Ions
2Cells
2.1Cell Structure
2.2Mitosis & Cancer
2.3Transport Across Cell Membrane
2.4Cell Recognition & the Immune System
3Substance Exchange
3.1Surface Area to Volume Ratio
3.2Gas Exchange
3.3Digestion & Absorption
4Genetic Information & Variation
4.1DNA, Genes & Chromosomes
4.2DNA & Protein Synthesis
4.3Mutations & Meiosis
4.4Genetic Diversity & Adaptation
4.5Species & Taxonomy
4.6Biodiversity Within a Community
4.7Investigating Diversity
5Energy Transfers (A2 only)
5.1Photosynthesis
5.1.1Overview of Photosynthesis
5.1.2Photoionisation of Chlorophyll
5.1.3Production of ATP & Reduced NADP
5.1.4Cyclic Photophosphorylation
5.1.5Light-Independent Reaction
5.1.6A-A* (AO3/4) - Photosynthesis Reactions
5.1.7Limiting Factors
5.1.8Photosynthesis Experiments
5.1.9End of Topic Test - Photosynthesis
5.1.10A-A* (AO3/4) - Photosynthesis
5.2Respiration
5.3Energy & Ecosystems
6Responding to Change (A2 only)
6.1Nervous Communication
6.2Nervous Coordination
6.3Muscle Contraction
6.4Homeostasis
6.4.1Overview of Homeostasis
6.4.2Blood Glucose Concentration
6.4.3Controlling Blood Glucose Concentration
6.4.4End of Topic Test - Blood Glucose
6.4.5Primary & Secondary Messengers
6.4.6Diabetes Mellitus
6.4.7Measuring Glucose Concentration
6.4.8Osmoregulation
6.4.9Controlling Blood Water Potential
6.4.10ADH
6.4.11End of Topic Test - Diabetes & Osmoregulation
6.4.12A-A* (AO3/4) - Homeostasis
7Genetics & Ecosystems (A2 only)
7.1Genetics
7.2Populations
7.3Evolution
7.3.1Variation
7.3.2Natural Selection & Evolution
7.3.3End of Topic Test - Populations & Evolution
7.3.4Types of Selection
7.3.5Types of Selection Summary
7.3.6Overview of Speciation
7.3.7Causes of Speciation
7.3.8Diversity
7.3.9End of Topic Test - Selection & Speciation
7.3.10A-A* (AO3/4) - Populations & Evolution
8The Control of Gene Expression (A2 only)
8.2Gene Expression
8.2.1Stem Cells
8.2.2Stem Cells in Disease
8.2.3End of Topic Test - Mutation & Gene Epression
8.2.4A-A* (AO3/4) - Mutation & Stem Cells
8.2.5Regulating Transcription
8.2.6Epigenetics
8.2.7Epigenetics & Disease
8.2.8Regulating Translation
8.2.9Experimental Data
8.2.10End of Topic Test - Transcription & Translation
8.2.11Tumours
8.2.12Correlations & Causes
8.2.13Prevention & Treatment
8.2.14End of Topic Test - Cancer
8.2.15A-A* (AO3/4) - Gene Expression & Cancer
8.3Genome Projects

Unlock your full potential with GoStudent tutoring
Affordable 1:1 tutoring from the comfort of your home
Tutors are matched to your specific learning needs
30+ school subjects covered