Flashcards in Hormonal Communication Deck (53)
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1
What is the endocrine system?
A communication system
Consisting of hormone secreting glands
2
What are the 2 types of hormone?
Protein based (adrenaline, insulin, glucagon)
Steroid (oestrogen, testosterone)
3
Where do protein hormones bind?
On the cell surface membrane
don't enter the cell as they aren't soluble in phospholipid membrane
4
Where steroid hormones act/ bind?
Can enter the cell as they are soluble in the membrane
enter the nucleus and have a direct impact on the DNA
5
Name glands in the endocrine system
Pituitary gland
thyroid gland
thymus
adrenal gland
pancreas
ovaries (females)
testes (males)
6
What are Target cells?
The cell that the hormone is intended to effect
7
What must a target cell have in order for a non-steroid hormone to act?
A specific receptor on the cell membrane that is complementary to the shape of the hormone
8
What is the first messenger?
Something that binds to the cell surface causing a change inside the cell
e.g non-steroid hormones
9
What is the second messenger?
A molecule released inside the cell as a result of the first messenger
stimulates a change in activity of the cell
10
What is activated when a hormone binds to the receptor on the cell surface membrane?
G protien
11
What does the G protein do once it is activated?
Activates an effector molecule
This is normally an enzyme that activates a second messenger
12
What is the most common effector molecule and what second messenger does it form?
Adenyl cyclase
converts ATP to cAMP
13
Where are the adrenal glands found?
Just above the kidneys
14
What are the 2 sections of the adrenal gland?
adrenal cortex
adrenal medulla
15
What are the 3 layers of the adrenal cortex?
Zona glomerulosa - outermost layer, secretes mineralocorticoids
Zona fasciculata - middle layer, secretes glucocorticoids
Zona reticularis - inner layer, secretes precursor to sex hormones
16
What does the zona glomerulosa secrete?
mineralocorticoids
17
What does the zona fasciculata secrete?
glucocorticoids
18
What does the zona reticularis secrete?
Precursor molecules to sex hormones
19
What does the adrenal medulla secrete?
Adrenaline
20
What type of hormones are made by the adrenal cortex? (steroid or non-steroid)
Steroid Hormones
21
How do steroid hormones work?
Pass through cell membrane
Bind with a receptor in the cytoplasm
Hormone-receptor complex passes into the nucleus
binds to receptor on the DNA
Drives production of mRNA which makes a specific protein
22
What is the function of mineralocorticoids?
Control Na+ and K+ concentrations in blood
as a result control blood pressure
23
What is the function of glucocorticoids?
control the metabolism of carbohydrates, fats andf proteins
e.g Cortisol can stimulate the production of glucose from stores
24
What kind of hormone is adrenaline?
non-steroid
25
What are the effects of adrenaline?
Relaxes smooth muscle in the bronchioles
Increased SV of heart
Increased HR
Vasoconstriction (increases blood pressure)
Stimulates glycogen to glucose conversion
Dilating pupils
Increases mental awareness
Inhibits action of the gut
Causing body hair to stand up
26
What is an exocrine gland?
A gland that releases hormones through a duct
27
In what way is the pancreas different to most other hormone-secreting organs?
It has both Endocrine and Exocrine functions
28
What is the exocrine function of the pancreas?
Secreting digestive enzymes into the small intestine through the pancreatic duct
29
Where in the pancreas are the digestive enzymes produced?
Acini
30
What is the structure of an Acinus?
exocrine cells that surround a tiny tubule
these tubules converge to form intralobular ducts that then converge to form the pancreatic duct
31
What are the three main enzymes in the pancreatic fluid?
Pancreatic amylase
Trypsinogen - inactive form of the protease Trypsin
Lipase
32
What is the name of the endocrine cells of the pancreas?
Islets of Langerhans
33
Which cells produce insulin?
Beta cells
34
Which cells produce Glucagon?
Alpha Cells
35
How is insulin released from the Beta cells? (long answer)
K+ channels are normally open so K+ can flow out
When glucose concentration is too high glucose move into Beta cell
It is metabolised into ATP
ATP closes K+ channels
accumulation of K+ alters the potential difference across membrane
This causes Ca2+ channels to open and Ca2+ to rush in
Ca2+ causes vesicles containing insulin to bind with cell membrane and are released by exocytosis
36
What is the name given to someone who's blood sugar falls too low?
Hypoglycaemia
37
What is the name given to someone who's blood sugar gets too high?
Hyperglycaemia or Diabetes if it is consistently too high
38
If blood glucose gets too high what will the body do to correct it?
Beta cells in the islets of Langerhans will secrete insulin to convert glucose to glycogen
39
What is the name given to the process where glucose is converted to glycogen?
Glycogenesis
40
Describe the hormone action of insulin on the cells?
Insulin is a non-steroid hormone so binds to surface receptor on the hepatocytes
Activates the enzyme tyrosine kinase which phosphorylates inactive enzymes within the cell
Cascade of reactions causes glucose transporter proteins to be released allowing more glucose into the cell to be converted to glycogen and fats
41
If blood glucose gets too low, what will the body do to correct it?
Alpha cells in the islets of Langerhans will secrete glucagon to convert glycogen to glucose
42
What is the name given to the process where glycogen is converted to glucose?
glycogenolysis
43
How does Glucagon work?
Glucagon is a non-steroid hormone so binds to surface receptor on the hepatocytes
Activates G-protein which activates adenyl cyclase
adenyl cyclase converts ATP to cAMP
cAMP activates enzyme catalysed reactions causing glycogenolysis
44
Why is blood glucose concentration control an example of negative feedback?
A change is brought about in order to oppose the change in blood glucose
If it is too high, insulin will reduce it
If it is too low, glucagon will increase it
45
What is Diabetes mellitus?
A condition where the body is unable to control blood glucose concentrations
Causes hyperglycaemia after a meal rich in carbohydrates or lipids
Causes hypoglycaemia after exercise or fasting
46
What causes Type 1 diabetes?
Autoimmune response in which the immune system attacks and destroys beta cells in the islets of Langerhans
Can be post viral
47
How can Type 1 diabetes lead to hypoglycaemia?
Because they cannot produce sufficient insulin they are unable to create glycogen stores when blood glucose is high (e.g after a meal)
This means when blood glucose is low there are no stores of glycogen to be hydrolysed and so they become hypoglycaemic
48
What causes Type 2 diabetes?
Where the person is able to produce insulin however this insulin is unable to have an effect on the hepatocytes
Blood glucose is almost always too high in Type 2 diabetes
49
What factors can bring an earlier onset of Type 2 diabetes?
Obesity
Lack of exercise
high sugar diet
Family history
Ethnicity (Asian or Afro-Caribbean)
50
What are the treatments for Type 1 diabetes?
Insulin injections (most common)
Insulin pump therapy - a small device pumps insulin into the bloodstream at a controlled rate
Islet cell transplant - Healthy beta cells transplanted into host
Pancreas transplant
51
What are the treatments for type 2 diabetes?
Lifestyle changes e.g:
Diet
More regular exercise
weight loss
in severe cases may use insulin injections
52
How has insulin become more available in recent years
Used to be extracted from pigs and cows
Produced by a GM bacteria
this allows mass production and made insulin a lot cheaper
53
