Hormonal Communication - 5 Flashcards
What is the endocrine system
Made of endocrine glands
What are endocrine glands
Specialised cells that secrete hormones directly into the bloodstream
What are exocrine glands
Specialised cells that secrete chemicals through ducts onto a surface
Examples of exocrine glands
Sweat
salivary
mammary
Mucous
What are hormones
Messenger molecules released by endocrine glands into the blood
Act as signals for target organs
Can be steroid, proteins, glycoproteins or polypeptides
What are the two types of hormones
Non-steroid
Steroid
What are non-steroid hormones
Often proteins
Do not enter the cell
Bind to receptors in the cell surface membrane
Name 3 types of non-steroid hormones
Adrenaline
Insulin
Glucagon
What are steroid hormones
Enter the cell
Have a direct effect on the DNA in the nucleus
Name 2 types of steroid hormones
Oestrogen
Testosterone
How do Non-steroid hormones work
Hydrophilic
The hormone is the first messenger
Cannot pass directly through cell membrane
Binds to specific receptors on cell surface of target cell
When hormone binds with complementary receptor, a G protein is activated
This activates an enzyme called adenyl cyclase,
Adenyl cyclase converts ATP to cAMP which is known as the second messenger
Camp acts directly on another protein
How to steroid hormones work
Lipid soluble
Pass through plasma membrane
Bind to steroid hormone receptors in cytoplasm or nucleus forming a hormone-receptor complex
Complex acts as a transcription factor
What hormones are produced from the adrenal cortex
Aldosterone
Cortisol
What hormone is produced from the adrenal medulla
Adrenaline
What does aldosterone do
Controls Na+ and K+ levels in the blood
What does cortisol do
Controls metabolism in the liver by decreasing synthesis of glycogen
What does adrenaline do
prepares the body for action
What is the exocrine function of the pancreas
Secretes digestive enzymes into pancreatic duct
What is the endocrine function of the pancreas
Secretes hormones directly into the blood
How does the exocrine function of the pancreas secrete enzymes
Pancreatic cells surround small tubules which drain into the pancreatic duct
Pancreatic cells produce pancreatic juice
What is pancreatic juice made up of
Amylase
Trypsinogen
Lipase
How does the endocrine function of the pancreas secrete hormones
Hormones are secreted from the cells in the islets of langerhans
Alpha cells manufacture and secrete glucagon
Beta cells manufacture and produce insulin
Hormones released directly into the blood
What is glycogenesis
The formation of glycogen from glucose
What is glycogenolysis
The breaking of glycogen to form glucose
What is Gluconeogenisis
Making new glucose
How does the body react to raised glucose levels
Alpha and beta cells in the isle of Langerhans detect a change in blood glucose levels
Alpha cells decrease glucagon secretion
Beta cells increase insulin secretion
This targets the hepatocytes and muscle cells
More glucose channels placed on the membrane, so more glucose enters
Glycogenesis occurs
Glucose converted to fats
More glucose used in respiration
How does the body react to low glucose levels
Alpha and beta cells in the isle of Langerhans detect a change in blood glucose levels
Alpha cells increase glucagon secretion
Beta cells decrease insulin secretion
This targets the hepatocytes
Glycogenolysis occurs
Glucose goes into blood
Uses fatty acids in respiration
Gluconeogenesis occurs
How are insulin levels in beta cells regulated
Cell membrane has potassium and calcium ion channels
Potassium ion channels normally open
When blood glucose concentration is high, glucose moves into the cell
Glucose is metabolised to produce ATP
ATP closes potassium ion channels
Build up of K+ ions alters the potential difference
This causes calcium ion channels to open
Calcium ions cause the vesicles of insulin to fuse with the cell membrane
releasing insulin by exocytosis
What is diabetes mellitus
Disease in which the body can no longer control its blood glucose levels
Pancreas either doesn’t produce enough insulin or body cant effectively respond to the insulin
What can diabetes mellitus cause
Hyperglycaemia or hypoglycaemia
What is type 1 diabetes
Patients are unable to produce insulin
usually develops during childhood
An autoimmune response which destroys beta cells
What is type 2 diabetes
Cant use insulin to control blood glucose levels effectively
beta cells don’t produce enough insulin or body cells don’t respond to insulin
What causes type 2 diabetes
Excess body weight
Physical inactivity
Overeating of refined carbohydrates
What are treatments for type 1 diabetes
Regular blood glucose monitoring
insulin injections
What are treatments for type 2 diabetes
Regulation of carbohydrate intake
Exercise
Weight loss
Drugs
Insulin injections
What are sources of insulin
Extracted from animals
Stem cells
Genetically engineered bacteria
Advantages of genetically modified insulin
Produced in a pure form so less likely to produce allergic reactions
Produced in higher quantities
Cheaper production costs
No ethical concerns
Advantages of stem cell therapy
Donor availability wont be an issue
Reduced likelihood of rejection
Removal of the need for insulin injections
Disadvantages of stem cell therapy
We do not know how to fully control the growth of stem cells
Concerns of formation of tumours due to unlimited cell growth
Ethical concerns
