5.4 Hormonal Communication Flashcards
What is a Hormone?
molecules(proteins or steroids) that act as messengers in the blood after being secreted from a gland
Define ‘Secretion’
production and release of a USEFUL substance by a gland or cell; also, the substance produced
What’s a target cell?
cells that possess a receptor, complementary to a peptide hormone, on their plasma membrane
What is Endocrine communication?
Specialised glands secrete hormones into bloodstream.
Circulatory system carries hormone to target cell/ tissue.
What is the Endocrine system?
a communication system that uses hormones as signalling molecules
Where are the Adrenal Glands located?
Above the kidneys
Describe ‘First & second messenger’
- Fist messenger: non-steroid hormone that bind to their receptor and initiate an effect inside the cell
- Second messenger: stimulates a change in the activity of the cell
What is the structure of the Adrenal Glands?
triangle-ish
outer part=cortex
inner part =medulla
What are the three layers (Zones) of the Adrenal Cortex?
- Zona glomerulosa- outer
- Zona fasciculata - middle
- Zona retucularis - inner
What hormone does the Adrenal Medulla secrete?
Adrenaline & Noradrenaline in response to danger, stress or excitement as part of the fight or flight response.
Which hormones does the Cortex secrete?
- Outer layter, Mineralocorticoids e.g. aldosterone: controls concentration of Na+ & K+ ions in blood.(outer layer)
- Midddle layer, Glucocorticoids: stimulates an increase in blood glucose concentration.(middle layer)
What are some effects of Adrenaline?
- Increase heart rate
- Increase stroke volume
- Dilate pupils
- Stimulate conversion of glycogen to glucose
What’s the Pancreas?
small organ below stomach with endo and exo-crine functions
What are the two main Pancreatic functions?
- secrete hormones from islets of Langerhans(endocrine)
* secrete pancreatic juices into small intestines(exocrine)
What’s the difference between Exocrine and Endocrine glands?
- Exocrine secrete substances into ducts
* Endocrine secret substances directly into the bloodstream
Why is it important that blood glucose concentration remains stable?
- Maintain constant blood water potential: prevent osmotic lysis/ crenation of cells.
- Maintain constant concentration of respiratory substrate: organism maintains constant level of activity regardless of environmental conditions.
What are the two types of Hormones?
- Lipid-soluble (steroid) hormones, diffuse into cell & bind to complementary receptor in cytoplasm.
- Peptide hormones, bind to complementary receptor on cell-surface membrane
Define Glycogenesis
glucose converted to glycogen
Define Glycogenolysis
hydrolysis of glycogen to glucose
Define Gluconeogenesis
glucose FROM amino acids & glycerol
What is the role of Glycogen?
maintains blood glucose concentration by acting as a storage version of glucose
What is Glucagon?
the hormone that helps control blood glucose levels by stimulating the liver to convert glycogen to glucose
What is Insulin?
a hormone that helps control blood glucose levels by stimulating conversion of glucose to glycogen
What are Alpha cells?
make up endocrine tissue in the pancreas, secrete Glucagon
What are Beta cells?
make up endocrine tissue in the pancreas, secrete insulin
What Homeostatic mechanism controls blood glucose level?
Negative feedback
What’s the mechanism for Insulins release?
- Beta cells contain Ca & k ions channels with k+ channels open so k+, -70mv
- when glucose conc high glucose rushes in
- glucose makes ATP, causes K+ channels to close
- K+ no longer leaves cell, charge increases
- potential difference change makes Ca+ channels to open
- Ca enters cell and causes insulin secretion
Outline the role of Insulin when blood glucose concentration increases
- β cells in Islets of Langerhans in pancreas detect decrease & secrete Insulin into bloodstream.
- Insulin binds to surface receptors on liver & muscle cells activating glycogenesis.
- Glucose eters cells, stuff happens
- β cells detect that blood glucose concentration has returned to optimum & stop producing Insulin (negative feedback).
Outline the role of Glucagon when blood glucose concentration decreases
- 𝞪 cells in Islets of Langerhans in pancreas detect decrease & secrete glucagon into bloodstream.
- Glucagon binds to surface receptors on liver cells activating glycogenolysis & gluconeogenesis.
- Glucose diffuses from liver into bloodstream.
- 𝛼 cells detect that blood glucose concentration has returned to optimum & stop producing glucagon. (negative feedback)
Use the secondary messenger model to explain how Glucagon works
- Hormone-receptor complex forms.
- Conformational change to receptor activates G-protein.
- Activates adenyl cyclase, which converts ATP to cyclic AMP (cAMP).
- cAMP activates protein kinase A pathway.
- Results in glycogenolysis.
What are some of the effects of Insulin?
- Glucose in cells converted to glycogen
- More glucose enters cells (increases cell permeability to glucose)
- More glucose used in respiration
- Inhibits glycogenolysis
Define & Explain the causes of Type 1 Diabetes mellitus
Body cannot produce insulin due to autoimmune response which attacks 𝛽 cells of Islets of Langerhans
How can type 1 Diabetes be controlled?
• Injecting insulin
• Islet transplant
• Pancreas transplant
*maybe stem cells in future
Define Type 2 Diabetes mellitus
Body doesn’t produce enough insulin various causes including
What are some risk factors for type 2 Diabetes mellitus?
- Poor diet (sugar rich)
- Lack or exercise/ sedentary lifestyle
- Obesity
- Ethnic origin (Black& Asian)
How can type 2 Diabetes be controlled?
can be treated by lifestyle changes like
• Regular exercise
• Carefully monitor diet
• insulin injections
What is the main source of Insulin, why is it different from say years ago?
used to be pigs but now genetically modified bacteria
What are the advantages to using Bacteria Insulin?
- cheaper and more efficient to produce
- Exact copy of human insulin so fast & effective
- Less chance of immune rejection
- less likely to raise ethical concerns
what are Acini
groups of acinus cells that group together to form tubules that form the pancreatic duct
what is the role of ducts
how Fluids are transported in the EXOcrine system, they move through theses instead of the blood
what is hypoglyceamia
Low levels of blood glucose, cells
what is hyperglyceamia, what would
High levels of blood glucose, cells lose water
