5.4 Hormonal Communication Flashcards
Define the endocrine system
A communication system using hormones as signalling molecules.
Define a hormone
cell signaling molecules that are produced by endocrine glands and are secreted into the blood to be carried to a target cells/tissue.
Define a target cell
cells that possess a specific receptor on their plasma membrane. Shape of receptor complimentary to hormone
What are the two types of hormone?
Peptide
Steroid
Name some examples of peptide hormones.
Adrenaline, insulin, glucagon
Name some examples of steroid hormones.
Oestrogen and testosterone.
How do hormones reach target cells?
They are secreted into capillaries that travel through glands.
How do steroid hormones activate cells?
They dissolve through the cell surface membrane and bind to internal receptors
How do peptide hormones activate cells?
They bind to external receptors on the plasma membrane
Where is the adrenal gland found?
On top of the left kidney
What is the outer layer of the adrenal gland?
The cortex
What is the middle layer of the adrenal gland?
The medulla
what type of hormones does the cortex secrete?
Steroid
What type of hormone does the medulla secrete?
peptide
What is the proper word for steroid hormones?
Corticosteroids
Name the three steroid hormones
Mineralocortocoids
Glucocorticoids
Androgens
Name the peptide hormone
Adrenaline
Give an example and the function of a mineralocorticoid
Aldosterone
Increases absorption of Na+ in the kidneys
Cl- in the blood
Controls water retention and blood pressure
Give an example and a function of a glucocorticoid
Cortisol
Increase of carbohydrate metabolism during stress
Give an example and function of an androgen
The building blocks of oestrogen and testosterone
Promote reproductive development
How are the receptor sites different for peptide and steroid hormones?
On the CSM vs. inside cell
Why do different hormones need different receptor sites
Hormones have different shapes
Different complimentary receptor needed for each hormone
Target cells only possess receptor complimentary to hormone
What is the role of acini in the pancreas
produce pancreatic enzymes that drain into the acinar lumen in the center
What are the roles of the alpha and beta cells in the islets of Langerhans?
Alpha- glucagon
Beta-insulin
Describe the exocrine tissues in the pancreas
-lobules containing many acini
-acini made of cells surrounding lumen, digested enzymes secreted into duct
-ducts collect together to form intralobular ducts
-these combine to form the main pancreatic duct
Describe the endocrine tissues in the pancreas
-Islets of Langerhans
-apha cells secrete glucagon into the pancreatic blood vessels
-beta cells secrete insulin into the pancreatic blood vessels
Describe the process in which beta cells in the pancreas are stimulated to secrete insulin
- K+ ions normally diffuse out of K+ ion channels
2.Increase in blood glucose conc. -> glucose diffuses into cell
3.Glucose metabolised into ATP
4.ATP closes K+ ion channels - Buildup of K+ conc. changes potential difference
- Causes Ca2+ ion channels to open and Ca2+ ions to diffuse in
- Ca2+ ions cause vesicles containing insulin to fuse to CSM.
Define glycogenisis
The creation of glycogen in the liver by removing glocose from the blood
Define gluconeogenisis
Formation of new glucose from other biological molecules such as lipids and amino acids
Define glycogenolysis
The breakdown of glycogen supplies in the liver and muscle tissues
Describe the process that occurs when the blood glucose concentration drops and is returned to homeostasis.
What two processes occur during this?
- Decrease in blood glucose concentration detected by 𝛼-cells in the islets of langerhans
- 𝛼-cells secrete glucagon
-glucagon detected by receptors on liver cells
-glycogen -> glucose - glucose -> blood
Mainly glycogenolysis but also gluconeogenesis
Describe the process that occurs when the blood glucose concentration increases and is returned to homeostasis.
What process occurs during this?
- Increase in blood glucose concentration is detected by 𝛽-cells in the islets of langerhans
- 𝛽-cells secrete insulin
- receptors on liver and muscle cells detect insulin
- liver and muscle cells remove glucose from blood and convert it into glycogen in a process called glycogenesis
What kind of feedback system controls blood glucose concentration
negative feedback
Describe negative feedback
A system which reverses a change applied to it through antagonistic effectors
Describe the process that occurs when insulin binds to receptors on liver cells
- Insulin binds to receptor
- Activates Tyrosine Kinase enzyme
- Phosphorylates (activates) inactive enzymes that cause…
- Vesicles containing glucose transport proteins to fuse to CSM
- More glucose diffuses in and is converted to glycogen
- More glucose is converted to fats and used for respiration
Describe the process that occurs when glucagon binds to receptors on liver cells
- Glucagon binds to receptor on CSM
- Activates G protein
- Activates adenyl cyclase, causing the activation of cAMP
- cAMP then activates inactive enzymes to…
- Convert glycogen to glucose (glycogenolysis)
- More fatty acids used in respiration
- Amino acids and lipids converted to glucose (gluconeogenesis)
Define Diabetes mellitus
A condition in which blood glucose concentration cannot be controlled effectively
How does type 1 diabetes occur? What is the problem?
Autoimmune disease
(could also occur as a result of a viral attack)
The pancreas can no longer produce insulin and store glycogen
How does type 2 diabetes occur? What’s the problem?
obesity, lack of regular exercise, family history
Can produce insulin but not enough. Probs because receptors become less receptive
How do we treat type one diabetes?
- Insulin injections: blood glucose concentration can be monitored and insulin injected as required
- Insulin pump: automatically injects required amount of insulin
- Islet cell transplant: healthy 𝛽 cells are transplanted
- Complete pancreas transplant
- Stem cells from bone marrow or embryo
What are the treatments for type 2 diabetes?
- Lifestyle changes
- There are some medications that slow down the amount of glucose released into the blood from the liver
Where do we get insulin from?
GMO bacteria
What are the advantages of using insulin from bacteria?
- An exact copy of human insulin so faster acting and more effective
- Less chance of developing tolerance to insulin
- Lower risk of infection
- Cheaper to manufacture vs. extracting from animals
- Less likely to have moral obligations vs. from a pig
