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Biology > 5:1:4 Hormonal Communication > Flashcards

5:1:4 Hormonal Communication Flashcards

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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

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2
Q

Label the endocrine system

A
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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)
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4
Q

Describe how hormones are first and second messengers

A
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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)
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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)
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7
Q

What is the pancreas

A
  • Organ found in the abdomen of animals
  • Functions as an endocrine and exocrine gland
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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

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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
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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
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11
Q

How is the histology of the pancreas studied

A
  • Sections are stained and viewed under the microscope
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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
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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
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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
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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
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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

Biology (25 decks)

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