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5.4 Hormonal Communication - Coggle Diagram
5.4 Hormonal Communication
Hormonal Communication
Role of Endocrine System
It uses hormones to send information about changes in the environment around the body to bring about a designated response.
It consists of endocrine glands that secrete hormones directly into the bloodstream.
These glands include the pancreas, adrenal glands, and the pituitary gland. The pituitary gland, located at the brain's base, produces various hormones that regulate the release of other hormones from different glands.
Role of Hormones
These glands include the pancreas, adrenal glands, and the pituitary gland. The pituitary gland, located at the brain's base, produces various hormones that regulate the release of other hormones from different glands.
The process where hormones act as chemical messenger.
Hormones are produced by endocrine gland cells.
When stimulated , glands release hormones to their target cells.
The blood carries hormones to their target cells.
They attach to receptors on or inside the target cells.
The cells then respond to the hormones
Non- Steroid and Steroid Hormones
Non Steroid
Water Soluble (Hydrophillic)
Cannot diffuse across the phospholipid bilayer
Example- Adrenaline
Mechanism- Binds to receptors on the cell surface membrane of the target cells to acivate second messangers.
Steroid
Lipid Soluble (Hydrophobic)
Can diffuse across the phospholipid bilayer
Example- Oestrogen
Mechanism- Bind to receptor in the cytoplasm or the nucleus, forming a hormone receptor complex that acts as a transcription factor.
Comparing Neuronal and Hormonal Communication
Neuronal
Signals- Nerve Impulses
Transmission- By Neurones
Speed- Very Rapid
Spread- Localised
Duration of Effect- Short
Hormonal
Signals- Hormones
Transmission- By Blood
Spread- Widespread
Speed- Slow
Duration of Effect- Long
Adrenal Glands
Location and Structure of the Adrenal Gland
The adrenal glands are a pair of small, triangular endocrine glands located above each kidney. They are essential components of the body's endocrine system.
The adrenal glands consist of two main regions, surrounded by a capsule
Adrenal cortex – The outer region of the glands, responsible for producing vital steroid hormones.
Adrenal medulla – The inner region at the centre of the glands, known for producing catecholamine hormones.
Hormones Produced by Adrenal Cortex
Glucocorticoids- Regulate metabolism by controlling the conversion of fats, proteins, and carbohydrates to energy. Control blood pressure and stress responses. Regulate the immune response and suppress inflammation. Examples- Cortisol, corticosterone
Mineralocorticoids- Maintain blood pressure by balancing salt and water in the blood and body fluids. Examples- Aldosterone
Androgens- Regulation of sexual characteristics and cell growth. Examples- Testosterone
Adrenal and Noradrenaline
Adrenaline
Increases heart rate and blood pressure to increase blood flow to the muscles and brain.
Increases blood glucose levels.
Increases breathing rate.
Dilates bronchioles.
Noradrenaline
Increases heart rate.
Expands air passages.
Dilates pupils.
Narrows blood vessels in organs like the gut to reduce blood flow to regions that aren't helpful in the stress response.
Pancreas
The Role of the Pancreas as an Exocrine Gland
The pancreas predominantly consists of exocrine glandular tissue, made up of pancreatic acini. The acini contain acinar cells that produce digestive enzymes like amylases, proteases, and lipases, as well as alkaline pancreatic juice.
These substances travel through the pancreatic duct and are released into the duodenum, the initial segment of the small intestine where they assist in the digestion process.
The Role of the Pancreas as an Endocrine Gland
The pancreas can act as an endocrine gland using special cell clusters called the islets of Langerhans. The cells within the islets secrete different hormones directly into blood vessels.
Two types of islets
Beta (β) cells - They secrete the hormone insulin.
Alpha (α) cells - They secrete the hormone glucagon.
Insulin and glucagon are crucial in regulating blood glucose levels.
Glucose is essential for cellular respiration.
Extreme blood glucose levels can lead to osmotic imbalances in cells, potentially causing cell death.
How Insulin and Glucagon Control Blood Glucose
Increase in Blood Glucose
Beta cells secrete insulin
Decreased glucagon secretion
More glucose taken up by cells
Glycogenesis (Synthesizing glycogen from glucose)
Increased respiration
Decrease in Blood Glucose
Alpha cells secrete glucagon
Decreased insulin secretion
Less glucose taken up by cells
Decreased respiration
Glycogenolysis (Breakdown of glycogen into glucose)
Gluconeogenesis (Synthesizing glucose in the body from non-carbohydrate precursors)
The control of insulin secretion from β cells
1.Glucose enters β cells via transporter proteins.
Increased cellular respiration produces more ATP in mitochondria.
ATP prompts the closure of potassium ion channels.
This causes an increase in potassium ion concentration inside the cell.
The rise in potassium levels leads to depolarisation, opening calcium ion channels.
The calcium ion influx stimulates insulin release through exocytosis.
Diabetes
What is diabetes mellitus?
Diabetes mellitus is a condition characterised by improperly regulated blood glucose levels.
One sign of diabetes is glucose in urine, indicating that the kidneys are unable to reabsorb all glucose from the filtrate into the blood. This suggests that blood glucose levels exceed a healthy threshold.
People with diabetes often use a biosensor to monitor their blood glucose concentration using a small blood sample.
Type 1 and type 2 diabetes
Features of type 1 diabetes
Often results from an autoimmune disease destroying insulin-producing beta cells in the pancreas.
Leads to no insulin production and high blood glucose levels.
Typically develops in childhood or early adulthood.
Features of type 2 diabetes
Occurs when beta cells don't produce enough insulin or the body's cells resist insulin.
Results in higher than normal blood glucose levels.
Commonly develops later in life and is associated with obesity.
Treatments
Type 1
Regular insulin injections for most individuals.
Use of an insulin pump providing continuous insulin administration.
Pancreas transplants of healthy islet cells to enable some insulin production.
Careful blood glucose monitoring and a diet balanced with insulin dosage.
Exercise to help regulate blood glucose and insulin requirements.
Type 2
Diet control to reduce sugar intake.
Regular physical activity.
Medications to increase cells' sensitivity to insulin.
Medications to stimulate more insulin production in cells.
In some cases, insulin therapy is necessary to manage blood glucose levels.
Stem Cell Research
Stem cells have the unique ability to develop into any cell type. Research is exploring the use of stem cells to create new insulin-producing β cells.
How are they used?
Growing stem cells into β cells. Implanting these β cells into the pancreas of individuals with type 1 diabetes. This allows them to produce their own insulin.
Genetically Modified Bacteria
Genetically modified (GM) bacteria can be used to produce insulin for medical purposes.
Benefits
Reduced production costs.
Capability to produce insulin in large quantities.
Enhanced effectiveness.
Lower risk of allergic reactions.
Avoids ethical and religious concerns associated with animal-derived products.