5.4 Hormonal Communication Flashcards
D
Heart rate can be increased by the hormone adrenaline, which binds to cardiac cells.
Describe how adrenaline binds to cardiac cells.
Binds to receptor in cell surface membrane + glycoprotein
No production of hCG until 4 weeks
Rapid increase until 8 weeks
Levels peak at 8 weeks
Levels fluctuate after 19 weeks
hCG is a peptide hormone
Binds to cell surface receptor
Uses cAMP to bring about response in cell
Which molecule does oestrogen interact w when it changes cell activity
DNA
Cells produce more hCG than normal due to depression of genes synthesising more hCG
Regulation of metabolism
Glucocorticoids
What secretes adrenaline
Medulla
Aldosterone
Controls blood pressure by controlling na+ concentration in blood and water reabsorption
A
B
Why’s it necessary to increase concentration of glucose surrounding cells before measuring insulin secretion
Glucose causes release of insulin
Change in insulin secretion high enough to be measured
Why’s standard deviation better
Less affected by anomaly
Takes into account every value in the data
Aspects of experimental design needed to be considered when comparing blood glucose concentration in patients
Blood glucose measured same number of times a day
Take into account patients age
Contractions cause more oxytocin to be released which causes more contractions. What’s this an example of
Positive feedback
Neuronal communication
Fast and short term
Hormonal communication
Slow and long term
Exocrine function
Synthesis of products to be released into ducts
Hormones
chemical messengers, signalling molecules
Glands that produce hormones = endocrine glands
Endocrine glands
Pituitary gland
Thyroid gland
Thymus
Adrenal glands
Pancreas
Ovaries
Testes
Which gland produces ADH
Posterior pituitary
Types of hormones
Peptide and steroid
Peptide hormones
made from amino acids e.g. adrenaline, insulin and glucagon = not lipid soluble so binds to receptors at the cell membrane
Steroid hormones
usually made from cholesterol e.g. oestrogen and testosterone and progesterone = lipid soluble = receptor found inside a cell
Endocrine glands
ductless glands = bundle of cells next to eachother that make the hormones + release them directly into the blood = travels directly to the target tissue
Target cell/tissue
has complementary receptors for a specific hormone
Peptide hormones
- Hormone = first messenger
- When the hormone binds to its receptor on a target cell it activates a G protein
- G protein activates enzyme adenylyl cyclase
- Adenyl cyclase converts ATP to cAMP (cAMP = secondary messenger)
- cAMP causes an enzyme cascade
Steroid hormones
- steroid hormone crosses the cell membrane and binds to a complementary receptor in the cytoplasm = receptor-hormone complex
- Receptor-hormone complex goes into the nucleus and can bind to specific receptors on the chromosome + can act as a transcription factor = stops, starts, amplifies or dampens
Adrenal gland diagram
3 sections of adrenal cortex from outer to inner
GFR
zona glomerulosa
Zona fasciticulata
Zona reticularis
What type of hormones are in the adrenal cortex
Steroid hormones
Zona glomerulosa
produces mineralocorticoids e.g. aldosterone
Function of aldosterone
controls body’s salt concentration = affects blood pressure
Zona fasciculata
produces glucocorticoids e.g. cortisol.
Function of cortisol
stress hormone + helps when your blood sugar is low = allows you to release stored glucose from your liver
Zona reticularis
helps produce sex hormones = produces the precursors which are then released + go to the site e.g. testes + ovaries and become the complete sex hormone
Adrenal medulla
- produces adrenaline = fight or flight hormone = peptide hormone = increases heart rate, increases blood glucose concentration, increases blood flow to muscles, causes pupils to dilate, decrease blood flow to gut, dilation of bronchioles
Noradrenaline has the same typa functions
Where is the pancreas
Organ Behind the stomach
Pancreas endocrine role
to produce hormones e.g insulin and glucagon
Exocrine role of pancreas
to produce pancreatic juice = helps you digest food, contains pancreatic enzymes which includes amylase, trypsinogen (inactive protease until needed then converted to trypsin), lipase and sodium hydrogen carbonate
Exocrine cells in pancreas
- have a duct in a bundle known as acinis = make all digestive enzymes + release them into the duct in the middle which travels to the small intestines (duodenum)
Compare endocrine and exocrine in pancreas
- endocrine are ductless, exocrine has ducts
- Exocrine function of pancreas is to release digestive enzymes + pancreatic juice, endocrine function is to produce hormones
- Exocrine cells used = acinis, endocrine cells are alpha and beta cells found I. The islets of langerhans
Endocrine cells in pancreas
Alpha and beta cells
Alpha cells in pancreas
produce glucagon (increase blood glucose concentration)
Beta cells in pancreas
- beta cells produce insulin (decreases blood glucose concentration)
- Beta cells usually smaller than alpha cells
Pancreas cells diagram
Role of insulin
- once blood glucose concentration is really high = steep concentration gradient, glucose diffuses into the cell
- Glucose metabolised into ATP using glucokinase
- ATP closes the potassium ion channels = potassium builds up in the cell so charge becomes less negative
- Change in voltage opens voltage gated calcium ion channels
- Calcium ions enter which causes vesicles containing insulin to move towards the plasma membrane to fuse + release the content via exocytosis
Blood glucose concentration
normal blood glucose concentration is between 4-6 mmol dm^-3 = if below this then hypoglycaemia, if above this then hyperglycaemia
Hypoglycaemia
tiredness, if brain doesn’t get enough glucose it can lead to coma or death = brain cells die
Hyperglycaemia
if only happens once it’s fine, if permanently above 7 it can cause vascular damage + damage to organs. If above 7 for a long time = diabetes
If blood glucose rises too high
- insulin produced = peptide hormone
- When it binds to the receptor it activates an enzyme called tyrosine kinase = phosphorylates an inactive enzyme into an active enzyme
- Active enzyme promotes conversion of any glucose to glycogen (glycogenesis), any excess glucose into fat, promotes use of glucose into respiration and promotes addition of glucose transporters into the cell membrane = more glucose can enter your liver cells = less in blood so blood glucose concentration should decrease
Glycogenesis
Glucose to glycogen
Glycogenolysis
Glycogen to glucose
Gluconeogenesis
Glucose from amino acids + fats
If blood glucose drops too low
- glucagon released = works in G protein system
- converts glycogen to glucose (glycogenolysis), make glucose from amino acids + fats (gluconeogenesis)
Negative feedback loop for blood glucose concentration
How is someone classified as diabetic
- when your blood glucose concentration is above 7mmol dm^-3 for a prolonged period of time
Blood glucose and insulin graph
- Normal people when they eat something their blood glucose concentration will rise and then go back down
Type 1 diabetes
Results from shortage of beta cells = not enough insulin produced
autoimmune disease, when your own immune cells attack your beta cells which means you don’t produce insulin. Usually genetic or triggered by a virus. Because they don’t have insulin they don’t know how to store glucose into glycogen so even if they have a low glucose concentration they have nothing to release glucose from. This means they’re prone to getting hypoglycaemia as well as hyperglycaemia.
Type 2 diabetes
Insulin resistance = insulin still produced but livers cells no longer respond to insulin bc of damaged receptors Causes: obesity, lack of exercise, diet
What cells do glucagon and insulin primarily bind to
Liver cells
Type 1 diabetes treatment
- insulin injections
- Islet cell transplantation
- Complete pancreas transplant
- In the future = use stem cells to grow islet of langerhans cells and put those into patients
Type 2 diabetes treatment
- low sugar diet
- exercise
- manage weight
- If still can control diabetes then take medication = reduces release of glucose from the liver + promotes release of insulin from the pancreas (control glucose levels e.g. metformin)
How to get insulin for diabetes - past and advantages and disadvantages of it
From animal pancreas e.g. pig
Advantages: tried and tested method, early treatment kept people alive
Disadvantages: risk of allergic reaction, high production cost, ethical issues of animal products
Advantages of genetically modifying insulin
exact copy of human insulin so faster acting + more effective, less risk of infection, less chance of rejection due to immune response, cheaper, less likely to have moral objections
Why does diabetes cause excessive hunger
- The food eaten isn’t being processed into energy so the body assumed they aren’t getting energy and thus hungry
Why does diabetes cause weight loss
- Can’t use the glucose so your body breaks down fat stores for energy
Why does diabetes cause tiredness
- The cells aren’t taking in the glucose so it isn’t able to be converted into energy.
Why does diabetes cause dehydration
Low water potential so water moves out of the cells which mean they don’t have enough water = dehydrated so can’t carry out action so send message to brain that they’re dehydrated
State 3 differences between type 1 and type 2 diabetes
T1 = childhood. T2 = adulthood
T1 = doesn’t produce enough insulin, T2= inability to effectively use the insulin bc doesn’t bind to glycoprotein receptors
T1= insulin injections. T2= might not need insulin injections instead work on diet and environment
D
- IV: conc of GH injected
- DV: rate of growth
- control: animal species
- trial populations over several months
- control group to ensure validity
- method for assessing growth = growth rate to allow comparability
- ensure food consistent across all trial groups
- large sample size to reduce effect of anomalies
- ethical concerns = chickens should be reared in humane conditions
K = islet of langerhans
L = blood vessel
Suggest and explain which statistical test the researchers would have used to analyse their data.
Unpaired t-test because they’re comparing means
Probability less than 0.1% so results due to chance
Stem cell therapy is a potential future treatment for diabetes mellitus.
In the future, it might be possible to differentiate stem cells in a laboratory (in vitro) before they are implanted into the pancreas of a patient with diabetes.
Which type of diabetes mellitus is most likely to be improved by stem cell therapy?
- type 1 bc it results from shortage of beta cells so stem cell therapy might increase insulin production and type 2 diabetes usually results from insulin resistance rather than lack of insulin so unlikely to help type 2
Type of diabetes
Age
Gender
How to get insulin for diabetes - current
- from genetic modification
- transplant of pancreas
- transplant of stem cells
Advantages and disadvantages of human insulin
Advantages: less risk of allergic reaction, lower production cost, overcomes ethical issues of animal products
Disadvantages: side effects of pumps e.g. hard lumps forming under skin, people persuaded to change from previous insulin regime
Advantages and disadvantages of transplant as diabetes treatment
Advantages: no need for insulin injections, improved quality of life, stem cells turned into functioning b-cells
Disadvantages: need to take immunosuppressants, ethical issues associated with stem cells, risk of cancer with stem cells
