Biology > Hormonal control > Flashcards

Hormonal control Flashcards

(46 cards)

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1
Q

homeostasis

A

the maintenance of a stable equilibrium in the conditions inside the body within a narrow limit

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2
Q

three key homeostatic mechanisms

A
  • thermoregulation
  • osmoregulation
  • control of blood glucose concentration
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3
Q

hormone

A

a chemical messenger produced by an endocrine gland that travels around the body in the bloodstream

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4
Q

endocrine gland

A

a group of cells that secrete hormones directly into the bloodstream

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5
Q

endocrine vs nervous system (3)

A

endocrine - slower, long-term, widespread
nervous - immediate, short-term, localised

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6
Q

what stimulates hormones to be produced? (3)

A
  • other hormones
  • nerve impulse
  • change in concentration of a specific substance
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7
Q

how do hormones reach target organs?

A
  • hormones are secreted directly into the blood plasma
  • hormones diffuse out of blood plasma and bind to specific complementary receptors in the plasma membranes of target cells (binding site)
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8
Q

steroid hormones

A
  • lipid soluble, pass through the phospholipid bilayer
  • hormone binds to receptors in the cytoplasm or the nucleus
  • hormone-receptor complexes act as transcription factors
  • example: oestrogen
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9
Q

non-steroid hormones

A
  • hydrophilic, cannot pass through the phospholipid bilayer
  • hormone binds to receptors in the plasma membrane
  • triggers a cascade reaction executed by second messengers
  • example: adrenaline
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10
Q

first messenger

A

the hormone secreted by an endocrine gland that signals the target cells

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11
Q

second messenger

A

the molecule that triggers the effect by causing a cascade reaction (cAMP in the response to adrenaline)

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12
Q

adrenal glands location

A

above the kidneys

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13
Q

adrenal gland structure and hormones

A

adrenal cortex - cortisol, corticosterone aldosterone and small amounts of oestrogen and testosterone (hormones are vital to life)
medulla - adrenaline, noradrenaline (non-essential hormones)

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14
Q

cortisol function (1)

A

primary stress hormone regulates metabolism of glucose, proteins and fats to release usable energy

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15
Q

corticosterone function (2)

A
  • regulate the immune response
  • suppress inflammatory reactions
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16
Q

aldosterone function (1)

A

regulates levels of Na and K salts and the water balance in the blood (to maintain blood volume and pressure)

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17
Q

adrenaline function (2)

A
  • increases heart rate to transport more blood to the brain and muscles
  • increase blood glucose concentrations by converting glycogen to glucose in the liver
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18
Q

noradrenaline function (4)

A
  • increases heart rate
  • widens pupils
  • widens air passages in lungs
  • vasoconstriction of blood vessels in non-essential organs (increases blood pressure)
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19
Q

exocrine function of the pancreas

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A
  • produce pancreatic juice containing digestive enzymes
  • delivered to small intestine
20
Q

endocrine function of the pancreas

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A

Islets of Langerhan:
- alpha cells secrete glucagon
- beta cells secrete insulin

21
Q

ABBA pneumonic

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A

ABBA

Alpha
Below (low [glucose], secrete glucagon)
Beta
Above (high [glucose], secrete insulin)

22
Q

Three ways in which glucose can enter the bloodstream:

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A
  • absorption in gut (from carb digestion)
  • glycogenolysis (hydrolysis of glycogen)
  • gluconeogenesis (convert lipids/lactate/amino acids into glucose)
23
Q

consequences of low blood glucose concentration

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A

cells don’t have enough glucose for respiration so don’t function properly

24
Q

consequences of high blood glucose concentration

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A

high blood pressure
(glucose lowers water potential in blood, water moves out of cells and into bloodstream)

25
what features might you see in a micrograph of pancreatic tissue?
- Islets of Langerhans (stained lighter) - exocrine tissue (surrounding tissue stained darker) - connective tissue - pancreatic ducts (empty) - blood vessels
26
sequence of responses if blood glucose concentration is too low
- detected by α cells - α cells secrete more glucagon, β cells secrete less insulin - glucagon binds to receptors of target cells in the liver causing a confirmational change in the receptors protein - activates a G protein which activates adenylyl cyclase - adenylyl cyclase catalyses conversion of ATP --> cAMP - cAMP acts a secondary messenger by causing an enzyme cascade - stimulates glycogenolysis and gluconeogenesis
27
how do the β cells detect and secrete insulin?
- glucose molecules enter β cells by facilitated diffusion - β cells respire glucose and produce ATP - high [ATP] closes K+ channels in the β cells to close changing membrane potential - voltage gated Ca2+ channels open which stimulate insulin containing vesicles to move towards plasma membrane - insulin releases into capillaries via exocytosis
28
outline the enzyme cascade in response to glucagon
- cAMP binds to protein kinase A enzymes - PKA activates phosphorylase kinase enzymes (by phosphorylating them) - phosphorylase kinase enzymes activate glycogen phosphorylase enzymes which catalyse glycogenolysis - gluconeogenesis also stimulated (glycerol/amino acids --> glucose etc)
29
sequence of responses when blood glucose concentration is too high
- detected by β cells - α cells secrete less glucagon, β cells secrete more insulin - insulin binds to specific receptors on target cells in liver - more glucose channels incorporated into plasma membranes which increases the permeability to glucose - more glucose diffuses into target cells - glucose used in respiration and glycogenesis
30
three examples of target cells of insulin
- skeletal muscle cells (increase rate of respiration) - fat storage cells (increase glycogenesis) - liver cells (increase glycogenesis)
31
reason for type 1 diabetes
- pancreas produces insufficient insulin - autoimmune response damaging β cells - lack of insulin affects glycogen stores (leading to fatigue)
32
type 1 diabetes treatments
- regular blood tests - insulin injections - appropriate diet - increase physical activity
33
what would be an appropriate diet for diabetic patients?
- five a day - minimal processed food - more polysaccharides than di/monosaccharides (slow release energy)
34
reasons for type 2 diabetes
receptors have reduced sensitivity to insulin (in liver and fat storage tissues) OR receptors have reduced in numbers
35
consequences of type 2 diabetes
- reduced glucose uptake --> high blood glucose concentration --> β cells produce a large amount of insulin which damages them
36
six risk factors of type 2 diabetes
- obesity - physical inactivity - high blood pressure - high blood cholesterol - genetics - specific ethnic groups
37
type 2 diabetes treatment
- appropriate diet (can be reversed if treated early) - increasing physical activity - drugs (stimulate insulin production or slow down rate of glucose absorptions from intestine or insulin injections depending on the cause)
38
why do diabetic patients have high blood pressure?
- high blood [glucose] - water diffuses into blood via osmosis - increases volume of blood - increases blood pressure
39
advantages of stem cell treatments for diabetes
- availability is less limited than pancreas donors - reduced likelihood of rejection - people no longer have to inject themselves
40
limitations of stem cell treatment in diabetes
- immunosuppressants must still be used for type 1 diabetes as it is an autoimmune disease - ethical concerns with the termination of embryos - tumours
41
gluconeogenesis
conversion of non-glucose sources into glucose
42
glycogenesis
conversion of glucose to glycogen
43
glycogenolysis
conversion of glycogen to glucose (in liver and muscle cells)
44
why is hormonal communication longer lasting than nervous communication?
hormones broken down less quickly than neurotransmitters
45
which adrenal hormones are controlled by the hypothalamus?
- cortisol - corticosterone
46
what stimulates aldosterone production?
signals triggered by the kidneys
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