5.1.4 Hormonal Communication Flashcards

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1
Q

Define Endocrine gland

A

group of cells which are specialised to secrete hormones into the blood

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2
Q

Define Exocrine gland

A

group of cells which are specialised to secrete enzymes into ducts

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3
Q

Define hormone

A

chemical messengers which travel in the bloodstream

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4
Q

Define target tissue

A
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5
Q

What are 8 endocrine glands?

A
  • Pituitary gland
  • Thyroid gland
  • Adrenal gland
  • Pineal gland
  • Thymus
  • Pancreas
  • Ovary
  • Testes
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6
Q

What is the general role of the pituitary gland and the hormones it releases?

A
  • produces growth hormones which control growth of bones and muscle
  • antidiurectic hormone (ADH) which increases reabsorption of water in kidneys
  • gonadotrophins which control development of ovaries and testes
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7
Q

What is the general role of the thyroid gland and the hormones it releases?

A
  • produces thyroxine which controls rate of metabolism
    and
    -the rate of glucose that is used up in respiration, promotes growth
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8
Q

What is the general role of the adrenal gland and the hormones it releases?

A
  • produces adrenaline which increases heart and breathing rate and raises blood sugar level
    (flight/fight response)
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9
Q

What is the general role of the testis and the hormones it releases?

A
  • produces testosterone which controls sperm production and secondary sexual characteristics
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10
Q

What is the general role of the pineal gland and the hormones it releases?

A
  • produces melatonin which affects reproductive development and daily cycles
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11
Q

What is the general role of the thymus and the hormones it releases?

A
  • produces thymosin which promots production and maturation of white blood cells
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12
Q

What is the general role of the pancreas and the hormones it releases?

A
  • produces insulin which converts excess glucose into glycogen in the liver
  • produces glucagon which converts glycogen back into glucose in the liver
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13
Q

What is the general role of the ovary and the hormones it releases?

A

-produes oestrogen which controls ovulation and secondary sexual characterstics
- progesterone + oestrogen which controls ovualtion and secondary sexual characteristics
-progesterone prepares uterus lining for recieving an embryo

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14
Q

Do endocrine glands secrete hormones or enzymes?

A

endocrine glands release hormones into the bloodstream

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15
Q

How does hormonal communication occur?

A
  1. endocrine gland secrete hormones into the blood stream
  2. the hormones travel to target cells
  3. the target cells have specific (to hormone) receptors
  4. after binding they coordinate a specific response
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16
Q

What are the 2 types of hormones?

A

-Steriod hormones
-Non-steriod hormones

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17
Q

Can steriod or non-steriod (peptide) hormones pass through the cell surface membrane?

A
  • steriod hormones can pass through the cell surface membrane
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18
Q

Why can non steriod hormones not pass through the cell surface membrane?
What do non-steriod hormones work? (mechanism)

A
  • non-steriod hormones cannot pass through because they are hydrophilic and the cell surface membrane has a hydrophobic core
    Instead:
    1. horomone binds to specific receptor (1st messenger) on c.s.m of target cell
    2. hormone binding to receptor activated enzyme on c.s.m to turn ATP into cAMP (second messenger)
    3. cAMP triggers cascade of reactions
    e.g. adrenaline
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19
Q

Why can steriod hormones pass through the cell surface membrane?
How do steriod hormones work? (mechanism)

A
  • they are lipid soluble so can diffuse through the lipid component of the c.s.m
  1. hormones diffuse through cell surface membrane
  2. hormones bind to steriod hormone receptors in cytoplasm/nucleus (dependant on which hormone)
  3. now there is a hormone receptor complex
  4. if receptor in nucleus: the hormone receptor complex acts as a transcription factor (facilitates/inhibits DNA transcription)
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20
Q

What is the location of the adrenal gland in the body?

A
  • adrenal gland found ontop of each kidney
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21
Q

What is the structure of the adrenal gland

A
  • adrenal gland has 2 sections
  • the inner region is the adrenal medulla (produces non essential hormones)
  • the outside is the adrenal cortex (produces vital hormones)
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22
Q

Which hormones does the adrenal medulla produce?

A

adrenal medulla: (produces non-essential hormones)
- produces peptide hormones (non-steriod)
-

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23
Q

Which 2 hormones does the adrenal medulla release? and what are their roles?

A

1) adrenaline
- increases heart rate
- increases blood glucose concentration
-2) noradrenaline
- increases heart rate
- widens pupils
- widens air passages to lungs
- vasoconstriction in blood vessels in non-essential organs = higher blood pressure

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24
Q

Which hormones does the adrenal cortex produce?

A

adrenal cortex: (vital to life hormones)
- produces steriod hormones

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25
Q

Which 3 hormones does the adrenal cortex release? and what are their roles?

A

1) glucocorticoids
regulates:
- glucose+protein metabolism
- blood pressure
- immune response
- suppress inflammatory reactions
2) mineralocorticoids
- maintain salt and water conc
3) androgens
- release small amounts of sex hormones which have v.little impact

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26
Q

Define Histology

A

the study of the microscopic anatomy of cells and tissues

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27
Q

What are the 2 roles of the pancreas?

A

Acts as:
- exocrine gland
- endocrine gland

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28
Q

What does the exocrine gland do (pancreas) ?
(4 steps)

A

exocrine gland:
1. produces enzymes
2. enzymes are secreted into ducts
3. ducts lead to pancreatic duct
4. enzymes are released into duodenum (top of s. intestine)

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29
Q

What does the endocrine gland do (pancreas)?

A

endocrine tissue (the islets of langerhans):
- produce and secretes hormones insulin and glucagon into the bloodstream

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30
Q

Draw a labelled diagram of a pancreas section and label it
snaprevise

A

on flashcard

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31
Q

What shape and colour do the pancreatic acini (exocrine tissue) appear under the microscope?

A

colour: darker stained
shape: small berry like clusters

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32
Q

What shape and colour do the islets of langerhans appear under the microscope?

A

colour: lightly stained
shape: large spherical clusters

33
Q

Define Islet of Langerhans

A

endocrine tissue which secretes insulin and glucagon directly into bloodstream
- made up of alpha+beta cells

34
Q

Define a (alpha) - cell

A

produce and secrete glucagon
- make up the islet of langerhans

35
Q

Define B (beta) - cell

A

produce and secrete insulin
- make up the islet of langerhans

36
Q

Define pancreatic acini

A
  • makes up exocrine tissue
  • collection of cells around a tubule which secrete enzymes
  • pancreatic acini makes up most of the pancreas
37
Q

How do the enzymes secreted by acini in the pancreas travel to the small intestine?

A
  1. Enzymes produced at the acini enter the tubules/ducts (which are surrounded by acini)
  2. enzymes travel through the pancreatic duct into the duodenum (top of small intestine)
38
Q

What are insulin and glucagon responsible for?

A

controlling blood glucose concentration

39
Q

What two hormones does the pancreas produce?

A

insulin and glucagon

40
Q

Which 3 digestive enzymes does the pancreas produce (exocrine tissue)? What is their role?

A

1) amylase - breaks down starch to –> simple sugars
2) Proteases - break down proteins to–> amino acids
e.g. trypsin
3) Lipases - break down lipids -to -> fatty acids + glycerol

41
Q

Define insulin

A
  • hormone secreted by B islet cells which regulates blood glucose concentration when b.g.c is too high
42
Q

Define glucagon

A
  • hormone secreted by a islet cells which regulates blood glucose concentration when b.g.c is too low
43
Q

How do you differentiate between alpha and beta cells?

A
  • differential stain
  • beta cells stain blue
  • alpha cells stain pink
44
Q

What controls the release of hormones from the adrenal medulla?

A
  • stimulation of the sympathetic nervous system
45
Q

What controls the release of hormones from the adrenal cortex?

A
  • hormoenes released from pituitary gland signal adrenal cortex to release hormones
46
Q

Define glycogenesis

A
  • birth of glycogen
  • converting glucose into glycogen
47
Q

Define glycogenolysis

A
  • breaking, glycogen
  • converting glycogen to glucose (in liver and muscle cells)
48
Q

Define gluconeogenesis

A
  • new birth of glucose
  • converting amino acids and glycerol into glucose
49
Q

What is the normal blood glucose concentration?

A

90 mg cm-3

50
Q

what do hepatocyte cells make up?

A

liver

51
Q

What are the two hormones which regulate blood glucose concentration?

A
  • insulin and glucagon
52
Q

Which hormone is released when blood glucose concentration is too high?

A

insulin

53
Q

How does insulin regulate blood glucose concentration?
(steps)

A
  1. B cells in islets of langerhans detect high levels of insulin
  2. B cells release insulin into bloodstream
  3. insulin binds to glycoprotein receptors
  4. a) increases rate of glucose uptake into cells
    b) increases glycogenesis rate
    c) inhibits glucagon release from a cells
    d) increases rate of respiration (increase need for glucose)
    e) increases rate of glucose to fat conversion
  5. decrease blood glucose concentration
54
Q

What are 3 other factors that affect blood glucose concentration?

A
  1. respiration
  2. diet
  3. alcohol consumption
55
Q

Which body cells have insulin receptors?

A

all body cells have insulin receptors (except RBCs)

56
Q

Why must insulin be constantly secreted to maintain its effect?

A
  • insulin is a protein so it is constantly being broken down by the liver
  • needs to be released continuously to maintain its effect
57
Q

Why is it important that insulin is constantly being broken down by enzymes?

A
  • so insulin doesnt continue to have its effect after blood glucose concentration reurns to normal
  • prevents hypoglycaemia (low blood sugar)
58
Q

Where does negative feedback come in with insulin?

A
  • decrease in blood glucose concentration detected by beta cells and insulin secretion reduced
59
Q

How does glucagon regulate blood glucose concentration?

A
  1. alpha cells of islets of langerhans dectect decrease in blood glucose concentration
  2. alpha cells release glucagon directly into bloodstream
  3. glucagon binds to its receptors (only on liver and fat cells)
  4. a) increases gluconeogenesis rate
    b) reduces amount of glucose absorbed by cells (more left in blood)
    c) increase glycogenesis
  5. alpha cells detect normal blood glucose levels
60
Q

What kind of hormone are insulin and glucagon?

A

antagonistic

61
Q

How is insulin secreted by beta cells in response to high blood glucose concentration?
(control of insulin secretion mechanism)

A
  • when blood glucose conc. rises above set level, beta cells of islets of langerhans detect it and release insulin: (mechanism)
    at normal blood glucose conc.
    1. K+ channels in plasma membrane of beta cells are open
    2. K+ ions diffuse out of cell
    3. Inside of cell at resting potential -70mV
    blood glucose conc. rises
    1. glucose enters b cell by glucose transporter
    2. mitochondria metabolises glucose producing ATP
    3. ATP binds to K+ channels and causes them to close (ATP sensitive K+ channels)
    4. K+ stops diffusing out of cell and builds up inside
    5. this depolarises the plasma membrane an potential difference inside cell wrt to outside reduces to -30mV
    6. depolarisation causes voltage gated Ca2+ channels to open
    7. Ca2+ ions enter the cell
    8. causes secretory vesicles to release insulin by exocytosis
62
Q

What is diabetes

A

when the pancreas doesnt produce enough insulin/the body doesnt respond to it

63
Q

What is type 1 diabetes?

A
  • patients are unable to produce insulin
    ( b cells in islets of langerhan do not produce insulin)
64
Q

What is type 2 diabetes?

A
  • body cells do not respond to insulin/or beta cells do not produce enough insulin
65
Q

How is type 1 diabetes caused?

A

autoimmune disease
- bodies immune system recognises body cells as foreign

66
Q

How is type 2 diabetes caused?

A
  • glycoprotein insulin receptors on cell surface membrane do not work properly
67
Q

What is hyperglycaemia?

A
  • raised blood glucose concentration above norm
68
Q

What is hypoglycaemia

A
  • blood glucose conc below norm
  • = unconsciousness/death
69
Q

Why might someone with diabetes usually have a b.g.c that is too high but not too low?

s+c

A
  • diabetes means b cells cannot produce insulin/or body cells do not react to insulin
  • so there is glucagon to raise b.g.c but no insulin to lower b.g.c
  • without insulin injections b.g.c will not go to norm
70
Q

Why might a person with diabetes struggle to raise blood glucose concentration when it is too low?

s+c

A
  • hypoglycemia (low b.g.c) occurs when there is too much insulin in blood
  • when eating something sugary they inject more insulin so b.g.c never increase
71
Q

table to compare Type 1 and Type 2 diabetes
- include potential causes
- what the problem is at a cellular level
- what problem is in respect to insulin
- the overall problem and treatments + symptoms
on paper flashcard

A
72
Q

How do insulin injections work?

A
  • increase amount of glucose absorbed by cells and cause glycogenesis to occur
  • results in reduction of blood glucose concentration
73
Q

What can be used if exercise and diet is not enough to control blood glucose concentration in type 2 diabetes?

A
  • drugs - stimulate insulin production
  • drugs which slow down rate at which body absorbs glucose
  • insulin injections
74
Q

What are 4 benefits of using insulin produced from genetically engineered bacteria rather than from pigs to treat diabetes?

A
  1. GMB insulin produced in pure form so no allergic reaction - antibodies are more similar to human ones
  2. insulin produced in larger quanities - higher yield of insulin
  3. production costs cheaper - bacteria do not require expensive food/resources - take up less space/time/less labour
  4. less ethical/religious concerns compared to cows/pigs
75
Q

How can stem cells be used to treat diabetes?

A

totipotent stem cells developed from embroys:
- totipotent stem cells differentiated into B cells of the islets of langerhans
- just a few b cells can restore pancreas functioning

76
Q

What are the benefits of stem cell treatment for type 1 diabetes over insulin injections/whole pancreas transplants?

A
  1. donor availability not an issue - unlimited source of b cells can be produced from stem cells/ pancreas’ available in small numbers
  2. less likely for rejection - embroyonic stem cells generally not rejected/stem cells can be made from SCNT
  3. less likely for rejection so no need for immunosuppressent drugs - less likely to catch infections due to low immunity
  4. no longer need insulin injections
  5. permanent cure
77
Q

What are 2 disadvantages of using stem cells to treat type 1 diabetes?

A
  1. difficult to control differentiation and cell growth - can form tumours
  2. ethical issues with using embryos
78
Q

Why is stem cell treatment not likely to be suitable for treating type 2 diabetes?

A
  • in type one beta cells in inslets of langerhans arent working properly (not producing insulin) and can be fixed by stem cell b cells because it is only 1 type of cell
  • in type 2 diabetes glycoprotein insulin receptors on all cells in body cannot respond to insulin so all cells that are unresponsive to insulin cannot be replaced.
  • (type 1 small one cell problem/type 2 larger harder problem)