5.1.4 Hormonal Communication COMPLETE Flashcards
DEFINITION- Hormone
Molecules secreted from endocrine glands directly into the bloodstream, carry signal from a gland to a tissue
DEFINITION- Endocrine Gland
A group of cells that secrete hormones directly into blood capillaries, i.e. insulin
DEFINITION- Exocrine Gland
Secrete molecules into ducts, i.e. bile, saliva
DEFINITION- Target Cells
Cells that possess a specific receptor on their plasma membrane
DEFINITION- First Messenger
They bind to a receptor on the plasma membrane causing the release of a secondary messenger (i.e. a hormone)
DEFINITION-Cyclic AMP
A secondary messenger, converted from ATP which activates many enzyme controlled reactions
DEFINITION- Second Messenger
Stimulates a response within the cell, promoted by hormones
DEFINITION- Pancreatic Duct
Carries the pancreatic juice to the small intestine
DEFINITION- Islets of Langerhans
Contain Alpha and Beta cells that secrete glucagon and insulin
DEFINITION- Insulin
Hormone that stimulates glucose being converted into glycogen (Beta)
DEFINITION- Glucagon
Hormone that stimulates glycogen back into glucose (Alpha)
DEFINITION- Glucose
A simple sugar that is used as a fuel in many organisms
DEFINITION- Glycogenesis
Glucose -> Glycogen (Liver)
DEFINITION- Gluconeogenesis
Amino Acids + Glycerol -> Glucose
DEFINITION- Glycogenolysis
Glycogen broken down into Glucose
DEFINITION- Adrenal Medulla
Part of the Adrenal Glands that secrete adrenaline when the body’s stressed
DEFINITION- Adrenal Cortex
Part of the adrenal gland that secretes steroid hormones
DEFINITION- Hepatocytes
Liver Cells
DEFINITION- Diabetes Mellitus
Regulation of glucagon and insulin doesn’t work so blood glucose levels are not regulated properly
DEFINITION- Hyperglycaemia
High Blood glucose causing damage to nerves and vessels
DEFINITION- Hypoglaecemia
Low blood glucose levels that may lead to loss of consciousness
DEFINITION- Exocytosis
Transportation of products through the cytoplasm and cell membrane
DEFINITION- Adrenaline
Stress hormone that is secreted to increases heart rate and breathing.
Fancy name for Diabetes
Diabetes Mellitus
Non steroid Hormones
e.g. adrenaline and insulin
derivatives from amino acids are water soluble and bind to the plasma membrane receptors generating a secondary messenger response
First Messengers
Bind to receptor on the cell surface membrane causing t release of a second messenger. Often act via a G protein
Second Messenger
Once G protein is activated, Adenylyl cyclase catalyses the conversion of ATP into cAMP which starts a cascade of enzyme controlled reactions
Steroid Hormones
e.g. testosterone and oestrogen
Lipid soluble so passes directly through the cell surface membrane and binds with a specific receptor in the cytoplasm
ADRENAL CORTEX- Mineralocorticoids
Control levels of Na+ and K+ in the blood. Maintaining blood pressure by increasing and decreasing their absorption
ADRENAL CORTEX- Glucocorticoids
Released in response to stress, stimulate glucose production by controlling metabolism of carbohydrates, fats etc.
ADRENAL CORTEX- Androgens
Taken in by the ovaries and testes and converted into sex hormones e.g. oestrogen
Adrenal Cortex Hormones
- Mineralocorticoids
- Glucocorticoids
- Androgens
Protein Kinases
Enzymes activated by cAMP which trigger the conversion of glycogen to glucose.
Location of the exocrine tissues in pancreas
ACINUS, cells found in groups surrounding tiny tubules
Exocrine details for pancreas
Pancreatic juice is released from cells and secreted into tubules at the centre of the group. These join to form interlobular ducts which join to form the pancreatic duct, joining to the duodenum.
Endocrine location in the pancreas
Islets of Langerhans, which are a group of lightly stained cells
Alpha Cells
Produce glucagon
Beta Cells
Produce insulin
Insulin Secretion from beta cells (Process )
- K+ diffuse out through channels, RP of -70mV
- Glucose enters cells via facilitated diffusion and becomes ATP
- K+ channels shut as sensitive to ATP levels
- K+ stop diffusing out so MP -30mV
- Change in MP cause Ca2+ channels to open
- They diffuse into cell and cause vesicles of insulin to be released
Glucose -> ATP
Glucose is phosphorylated by the enzyme Glucokinase , then its metabolised into ATP
Normal blood glucose concentration
90mg/100cm3
Reaction to high blood glucose
GLYCOGENESIS- glucose converted into glycogen in the liver and muscles. More used in respiration, converted into fats, more glucose transporter proteins
Reaction to low blood glucose
GLYCOGENOLYSIS - glycogen broken down into glucose in the liver
GLUCONEOGENESIS- amino acids and glycerol converted into glucose in the liver
More fatty acids used for respiration
Relationship between Insulin and Glucagon
ANTAGONISTIC, as have opposite effects so concentrations will fluctuate.
Type 1 Diabetes
- Beta cells cant produce insulin
- Unknown cause
- Symptoms are manageable
Type 2 Diabetes
- Can’t effectively use the insulin
- Beta cells don’t produce enough insulin/ not the proper response from insulin receptor
- Cells lose the responsiveness to insulin
- Result of of excess body weight and eating refined carbs
Type 1 treatments
- Regular insulin injections
- Prick finger to test blood for glucose
- insulin injections increase glucose absorbtion
Type 2 treatments
- Regulate carb intake and exercise to lose weight
- Drugs can stimulate insulin production
Advantages of GM Insulin
- Pure form so less likely to cause allergic reactions
- Can produce higher quantities
- Cheaper production costs
- Overcome ethical concerns withering animals
Stem Cells for diabetes treatment
- Replace the faulty beta cells in the islets of langerhans
- Demand for transplants outweighs the availability
- Beta cell injections usually less likely to be rejected than organ transplants
