5:1:4 Hormonal Communication Flashcards
1
Q
What is the endocrine system
A
A system of endocrine glands which produce hormones, which are chemical messengers to be carried in the blood and transfer information to control functions
2
Q
Label the endocrine system
A
3
Q
What do hormones do
A
- They are transported directly into the bloodstream, by endocrine glands
- They are transported around the body to target cells/tissues to bring about a response
- They only affect cells with receptors that the specific hormone can bind to to create and effect (complementary binding)
4
Q
Describe how hormones are first and second messengers
A
5
Q
Describe how first and second messengers carry out the action of a hormone
A
- The first messenger is the hormone that brings the information from the endocrine gland, and bind to the receptor on the cell surface membrane
- The second messenger inside the camel causes the effect (e.g. cAMP)
6
Q
Describe the structure and function of the adrenal glands
A
- Situated above each kidney, and consist of a central medulla and outer cortex
- Cortex produces steroid hormones (e.g. aldosterone to regulate salt/water in blood, and cortisol the stress hormone to regulate metabolism)
- Medulla produces adrenaline, which is produced at times of stress/excitement to prepare the body for emergency situations (fight or flight)
7
Q
What is the pancreas
A
- Organ found in the abdomen of animals
- Functions as an endocrine and exocrine gland
8
Q
What is the difference between endocrine and exocrine glands
A
Endocrine glands secrete hormones directly into the blood, whilst exocrine glands secrete substances via a duct
9
Q
What is the exocrine function of the pancreas
A
- To produce pancreatic juice (contains digestive enzymes) to be delivered to the small intestine to assist digestion
- These enzymes are secreted by exocrine tissue
10
Q
What is the endocrine function of the pancreas
A
- To product the hormones glucagon and insulin
- Islets of langerhans produce hormones within the pancreas, which contain alpha cells which secrete glucagon, and beta cells which secrete insulin
11
Q
How is the histology of the pancreas studied
A
- Sections are stained and viewed under the microscope
12
Q
What are the factors affecting blood glucose concentration
A
- Absorption in the gut following carbohydrate digestion
- Hydrolysis of glycogen stores
- Non-carbohydrates that have been converted to glucose
13
Q
How is blood glucose concentration controlled
A
- If the concentration of glucose in the blood decreases, cells may not have enough glucose to respire
- If the concentration of glucose in the blood increases, this can disrupt the normal function of cells
- Blood glucose in controlled by two hormones secreted by the islets of langherhans in the pancreas
- The islets of langherhans contain alpha cells which secrete glucagon, and beta cells which secret insulin
- These hormones act as receptors to control blood glucose levels
14
Q
Describe how the body responds to a decrease in blood glucose concentration
A
- The decrease is detected by the alpha cells, which start secreting glucagon and the beta cells which stop secreting insulin
- The decrease of blood insulin conc. reduces the use of glucose by liver and muscle cells
- Glucagon binds to receptors in the cell surface membrane of liver cells, causing a conformational change that activates the G protein
- The activated G protein activates enzyme adenylyl cyclase, which catalyses the conversion of ATP to the second messenger cyclic AMP
- cAMP binds to protein kinase A enzymes and activated them, causing them to activate glycogen phosphorylase enzymes which catalyse the breakdown of glycogen to glucose in a process called glycogenolysis
15
Q
How does adrenaline increase blood glucose concentration
A
- It binds to different receptors on the surface of liver cells that activate the same enzyme cascade and lead to glycogenolysis to produce glucose
- It also stimulates the breakdown of glycogen stores in muscles during exercise
16
Q
Describe how the body responds to an increase in blood glucose concentration
A
- The beta cells in the pancreas detect the increase in blood glucose levels, due to the glucose molecules entering the beta cells via facilitated diffusion
- The cells respire the glucose and produce ATP
- High ATP levels cause the potassium channels in the beta cells to close, changing the membrane potential
- This change causes the voltage gated calcium channels to open, and the beta cells recieve an influx of Ca2+ ions
- This causes the beta cells to secrete insulin, which moves in vesicles through the bloodstream and stimulates the uptake of glucose by muscle and fat cells and the liver
17
Q
Describe the action of insulin
A
- Muscle, fat, and liver cells possess glucose transporter protein, which are the target cells of insulin
- They allow the uptake of glucose molecules via facilitated diffusion, and are insulin sensitive
- Insulin binds to receptors on the target cells, which stimulates then to activate more glucose transporter proteins to their cell surface membrane, increasing the rate of glucose uptake
- Additionally, insulin increases the uptake of glucose in the liver by stimulating glycogenesis
- As glucose enters the liver an enzyme converts it to glucose phosphate, then to glycogen, lowering the glucose concentration
18
Q
How is blood glucose concentration regulated by a negative feedback control mechanism
A
- Receptors (alpha and beta cells) detect whether glucose levels are too high/low
- This is communicated through the hormone system (using glucagon and insulin)
- Effectors (liver/muscle/fat cells) react to bring the level back to normal
19
Q
What is glycogenesis
A
- The synthesis of glycogen from glucose molecules
- Insulin triggers this process after it detects high blood glucose molecules
20
Q
What is glycogenolysis
A
- The breakdown of glycogen to produce glucose molecules
- Glucagon triggers this process after detecting low blood glucose levels
21
Q
What is gluconeogenesis
A
- The synthesis of glucose molecules from non-carbohydrate molecules
- Triggered by glucagon which activates enzymes in the liver which convert the non-carbohydrate molecules
22
Q
What is diabetes
A
- A condition in which the homeostatic control of blood glucose has failed or deteriorated
- Insulin function is disrupted allowing blood glucose concentration to rise
- Type I and type II
23
Q
What is type I diabetes
A
- A condition where the pancreas fails to produce sufficient insulin to control blood glucose levels, normally beginning in childhood as an autoimmune response by attacking the beta cells
- The lack of insulin affects glucagon stores, resulting in fatigue
- High levels of blood glucose can result in organ damage
24
Q
How is type I diabetes treated
A
- Insulin injections after monitoring blood glucose levels and diabetes appropriate diet
- Insulin injections can be fast or slow acting depending on the different levels of control
25
Q
What is type II diabetes
A
- More common and usually develops in those aged 40 and over
- Pancreas still produces insulin, but the receptors have reduced/don’t respond therefore have reduced sensitivity to insulin
- This causes a reduced glucose uptake which leads to high blood glucose concentrations, leading to beta cells producing excess insulin which damages them
26
Q
What are treatments for type II diabetes
A
- Sugar and fat controlled diets
- Exercise regimes
27
Q
What are known risk factors of type II diabetes
A
- Obesity
- Physical inactivity
- High blood pressure
- High blood cholesterol
- Generics
28
Q
Why is high blood pressure associated with diabetes
A
- High blood glucose concentration lowers the water potential of the blood, causing water to move into the tissues via osmosis
X Causing a larger volume of blood in the circulatory system
29
Q
How can stem cells produce insulin
A
- Stem cells can be treated to differentiate into pancreatic beta cells
- These cells can be transplanted into the pancreas of the diabetic individual to allow them to produce insulin
- This is only an early stage research idea
30
Q
How can insulin be produced using GM bacteria
A
- DNA can be altered by adding nucleotides from another source
- The transgenic organism is classed as GM, and it’s recombinant DNA is used to produce proteins which can be manipulated to the original form of insulin
- Bacteria plasmids are modified to include the human insulin gene, which are then inserted into bacteria and then the body
- Administered intravenously instead of orally so the enzyme protease doesn’t digest it before it reaches the bloodstream
31
Q
What are the advantages of producing insulin using GM bacteria
A
- Identical to human insulin
- Reliable supply available
- Fewer ethical/moral/religious concerns
- Fewer rejection problems, side effects or allergic reactions
- Cheaper to produce
- Useful for those who have animal insulin intolerance
