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A2 BIOLOGY OCR > Hormonal communication > Flashcards

Hormonal communication Flashcards

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1
Q

Whats the difference between endocrine and exocrine glands

A
  • ENDOCRINE:
    • Contains cells that produce a hormone and release it straight into blood
    • Ductless
  • EXOCRINE:
    • Produce a chemical which isn’t directly released into the blood
    • Have a duct which carries secretion to another place
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2
Q

Describe the characteristics of protein/non-steroid hormones (e.g. insulin)

A
  • Not able to cross cell surface membrane so DONT enter cell
  • Hydrophillic so can’t pass through plasma membrane
  • Bind to specific receptors on membrane of target cells
  • Triggers a cell signalling cascade in cell
  • Often requires second messengers
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3
Q

Describe the characteristics of steroid hormones (e.g. progesterone)

A
  • Can pass through cell surface membrane and enter cell
  • Acts upon the DNA in the nucleus
  • Pass through plasma membrane and binds to steroid specific receptor in cytoplasm/ nucleus
  • Forms hormone-receptor complex that acts as a transcription factor for a gene
  • Acts to facilitate or inhibit a specific gene
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4
Q

Whats the function of the adrenal cortex

A
  • Uses cholesterol to produce certain steroid hormones (e.g. mineralocorticoids, glucocorticoids and androgens)
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5
Q

Describe what mineralocorticoids are.

A

ALDOSTERONE:

  • helps control blood pressure by maintaining the balance between salt and H2O conc in the body
  • its release is mediated by kidney
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6
Q

Describe what glucocorticoids are.

A

CORTISOL:
- involved in regulation of metabolism
- helps regulate blood pressure and cardiovascular function in response to stress
CORTICOSTERONE:
- works with cortisol to regulate immune response and suppress inflammatory reactions

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7
Q

Describe what androgens are

A
  • Hormones are converted elsewhere in body to female and male hormones however these are steroid hormones so are also produced in much larger amounts by the ovaries and testes
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8
Q

Whats the function of the adrenal medulla

A
  • Hormones here are released when the sympathetic nervous system is stimulated
  • Occurs when the body is stressed
  • produces peptide (catacoholamine) hormones
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9
Q

Describe the action of hormones

A
  • hormones act as first messengers because it carries the chemical message from the endocrine gland to the receptor o the target cells.
  • This then activates an enzyme in the cell which catalyses the production of a molecule inside the cell called a signalling molecule
  • the signalling molecule is the second messenger as it activates a cascade of reactions inside the cell
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10
Q

Whats adrenaline?

A
  • hormone that increases heart rate by sending blood quickly to muscles and brain
  • Also rapidly raises blood glucose conc levels by converting glycogen to glucose in the liver
  • first messenger that is an amino acid derrivative and can’t enter target cell
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11
Q

Whats noradrenaline?

A
  • Works with adrenaline in response to stress producing effect such as increasing heart rate, widening of pupils , widening of air passages and narrowing of blood vessels in non-essential organs
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12
Q

What are the actions of adrenaline?

A
  • Triggers the liver cells to undergo glycogenolysis so glucose is released into bloodstream
  • Allows respiration to increase so more energy is available for muscle contraction
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13
Q

What is cyclic AMP?

A
  • second messenger that not only relays signal molecules but amplifies their strength
  • cAMP is made from ATP by the enzyme andenylyl cyclase which is found on inner side of plasma membrane
  • Adenylyl cyclase is activated when first messengers e.g. hormones active adenylyl cyclase stimulatory G-protein coupled receptors
  • When activated the adenylyl cyclase convert ATP to cAMP which then activates protein kinase enzymes
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14
Q

How does adrenaline work?

A
  • Its a first messenger that binds to specific receptors and activates an enzyme in the membrane called adenylyl cyclase
  • this then catalyses the production of a second messenger called cyclic AMP from ATP and activates a cascade making more glucose available to the cell 9by catalysing breakdown of glucose to glycogen
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15
Q

Describe the structure of adrenal glands

A
  • Has inner part (medulla) and outer (cortex) that have diff functions
  • Have good blood supply
  • On the top of the kidneys
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16
Q

Describe the structure and function of the pancreas/islets of langerhans

A
  • gland under the stomach
  • composed largely of exocrine tissue
  • produces digestive enzyme and pancreatic juice which are secreted into duodenum via pancreatic duct
  • has endocrine tissue called islets of Langerhans –> found in clusters around blood capillaries and secrete hormones directly into blood
  • IoL made up of two types of cell (alpha and beta)
17
Q

Difference between alpha and beta cells

A 
ALPHA: 
- bigger and more numerous
- Makes glucAgon
BETA:
- smaller (nucleus takes up more room)
- makes insulin
  • A stain can be used to identify each
18
Q

Difference between endocrine and exocrine tissue

A 
ENDO (islets of langerhans)
- Lightly stained
- Large spherical clusters
- Produce and secrete hormones
EXO (pancreatic acini)
- Darker stained
- Small, berry-like clusters 
- Produce and secrete digestive enzymes
19
Q

How does insulin work?

A
  • lowers blood glucose conc
  • increases permeability of cell membranes to glucose so cells take up more
  • also activates enzymes that convert glucose into glycogen so its stored in cytoplasm (by glycogenesis)
  • also increases rate of respiration of glucose esp in muscle cells
20
Q

How does glucagon work?

A
  • raises blood glucose conc
  • activates enzymes that break down glycogen into glucose (glycogenolysis)
  • Also promotes formation of glucose from fatty acids and amino acids (glyconeogenesis)
  • also decreases rate of respiration of glucose in cells
21
Q

What happens when theres a rise in blood glucose conc

A
  • pancreas detects change and beta cells secrete insulin and alpha cells stop secreting glucagon
  • insulin bind to effectors and liver and muscle cells respond to decrease in blood glucose conc (e.g. glucogenesis)
22
Q

Describe the control of insulin secretion by beta cells

A

HIGH BLOOD GLUCOSE CONC DETECTED
- more glucose enters beta cells by facilitated diffusion causing rate of respiration to increase
POTASSIUM ION CHANNELS CLOSE
- Rise in ATP triggers K+ ion channels in plasma membrane to close and so K+ ions can’t enter beta cell so build up outside cell making inside of beta cell less negative
- plasma membrane of beta cell depolarised
CALCIUM ION CHANNELS OPEN
- Depolarisation triggers Ca+ ion channels to open so Ca+ enter beta cell
- This causes vesicles to move and fuse with the beta cell membrane releasing insulin by exocytosis

23
Q

What is Type 1 diabetes

A

-auto-immune disease where body attacks + destroys beta cells meaning people can’t produce insulin
- Can result in death if untreated
- risk slightly increased if theres family history
- can lead to HYPERglycaemia and HYPOglycaemia
HYPER = blood glucose conc too high (longterm effects)
HYPO = blood glucose conc too low (act drunk/ can lead to coma)

24
Q

What is Type 2 diabetes

A
  • inability to produce enough insulin or respond to insulin
  • usually acquired later in life than type 1
  • linked with obesity and poor diet
  • risk is increased in certain ethnic groups (asian, african) and if theres family history of it
25
Q

How do you treat type 1 diabetes?

A
  • Insulin injections (insulin pump)
  • Islet cell transplantation (usually needs insulin therapy alongside it)
  • ## Eating healthy diet, regular exercise etc.
26
Q

How do you treat type 2 diabetes?

A
  • Diet/Exercise
  • Weight loss
  • Drugs (e.g. metformin)
27
Q

What was the old way of producing insulin and what were its -ves?

A
  • Used to be produced from slaughtered animals pancreas (e.g. cows/ pigs
    NEGATIVES:
    -ethical concerns (vegetarians, religious groups etc)
    -not as effective as human insulin
  • Supply vs demand = expensive
  • Cost (not cost effective)
  • Disease transfer possibility
28
Q

What are the alternatives to the old way of producing insulin?

A
  • Pancreas transplant (type 1 only)
  • B cell transplant
  • Stem cells
    1) embryonic from IVF (totipotent) but ethical issues
    2) umbilical cord (pluripotent = not as good)
  • SCNT
29
Q

What are the advantages and disadvantages of SCNT

A
  • SCNT is using GM bacteria to produce insulin
    ADVANTAGES:
  • cheaper than extraction from animal pancreases
  • larger quantities can be produced using GM bacteria
    -GM bacteria make human insulin which is more effective and less likely to trigger an allergic response
  • More ethical
30
Q

How do hormones and nervous mechanisms effect heart rate?

A

BARORECEPTORS:
- detect blood pressure in aorta and carotid artery and send nerve impulses along sensory neurones to cardioregulatory centres in medulla oblongata to increase or decrease heart rate (via SAN)
CHEMORECEPTORS:
- detect chemical composition of blood
- in medulla of brain, carotid artery and aorta and detect O2, CO2 conc and pH in blood
PARASYMPATHETIC NEURONES:
- secrete acetylcholine which binds to receptors in the SAN which reduces rate of impulses sent from SAN to heart muscle so heart rate decreases
SYMPATHETIC NEURONES:
- secrete noradrenaline when they connect to SAN which binds to receptors in SAN and increases rate of impulses so increases heart rate

A2 BIOLOGY OCR (11 decks)

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