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HUBS 191 > Homeostasis of plasma glucose and Diabetes Mellitus > Flashcards

Homeostasis of plasma glucose and Diabetes Mellitus Flashcards

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1
Q

what are the normal range for plasma glucose concentration

A
  • 3.5 to 6 mmol/L when fasting (not eaten)
  • 3.5 to 8 mmol/L when not fasting (eaten)
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2
Q

why is blood glucose concentration so important

A
  • the brain cells are largely dependent on glucose as energy source
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3
Q

what can other cells use when glucose levels are low

A

they are able to use alternative substrate for ATP production

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4
Q

where is the pancreas located and what is the structure

A

in the curve of duodenum and consists of head, body and tail

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5
Q

what are 99% of pancreatic cells clustered into

A

acini

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6
Q

what do acini secrete

A

secretes enzymes

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7
Q

where does the acini secrete enzymes into

A

into ducts which empty into intestine - the exocrine gland

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8
Q

what are exocrine glands

A

organs or groups of cells that produce and release substances like sweat, tears, saliva, or digestive juices through ducts or openings onto a body surface or into the digestive tract

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9
Q

what are pancreatic islets or Islets of Langerhans

A

they are small clusters of endocrine cells that are scattered amongst the acini

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10
Q

what is the function of pancreatic islets

A

responsible for regulating blood sugar

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11
Q

what are the 4 types of endocrine cells in the pancreas

A
  1. alpha cells
  2. beta cells
  3. delta cells
  4. Pancreatic Polypeptide (PP cells)
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12
Q

what is the function of alpha cells in the pancreas

A

they secrete glucagon which increases BGL

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13
Q

what is the function of beta cells in the pancreas

A

they secrete insulin which decrease BGL

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14
Q

what type of hormone is insulin

A

a protein hormone

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15
Q

where is insulin synthesised

A

initially synthesised on rER of beta cells as preprohormone with A, B and C chains

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16
Q

how is the preprohormone of insulin changed to become a functioning hormone

A

the C chain is removed in the golgu apparatus and packaged into secretory vesicles, the insulin and C peptide is released from the beta cell when the BGLs rise

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17
Q

how long does insulin circulate the plasma

A

insulin circulates the plasma unbound and mostly cleared from circulation within 10-15 min

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18
Q

how can you tell when a person is creating their own insulin

A

when there is evidence of C chain in their blood as medical insulin would already be functional - won’t contain C chain

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19
Q

how does insulin correct hyperglycemia

A

by facilitating glucose uptake into cells of mostly body tissue

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20
Q

why does insulin facilitate glucose uptake

A

as without insulin, glucose can not be utilized by most cells for energy and blood glucose levels will be too high

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21
Q

what does insulin have to bind to when they want to enter the cell

A

insulin binds to 2 alpha subunits

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22
Q

what attaches to beta subunits to be able to go into a cell

A

beta subunits get phosphate groups attached from ATP

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23
Q

why do beta subunits get a phosphate group attached

A

the beta subunits are then able to phosphorylate proteins inside the cell that mediate the insulins effect - which are the substrates that insulin responds to

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24
Q

when insulin binds to the cell surface, what other structure is added to the surface in order for glucose to enter cells

A

GLUT4 transport proteins are inserted into the cell membrane of muscle and fat cells to transport glucose into the cell

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25
how does insulin increase the glucose entry in skeletal muscles
more GLUT4 transport proteins will be inserted into the cell membrane as the amount of insulin binding to the cell increases
26
what effect does insulin have on skeletal muscles
- increased glucose entry into muscle cells via GLUT4 - increased glycogen synthesis in the muscle (assuming they are exercising at the time) - increased transport of amino acids into muscle (and other cells) - increase protein synthesis - inhibition of proteins
27
how do muscles get energy when glucose and insulin levels are low
muscles use fatty acids then for energy and the exercise itself causes the translocation of GLUT4 to cell membrane in skeletal muscle
28
how does insulin effect adipose (fat tissue)
- increased glucose transport into adipose cells via GLUT4 via facilitated diffusion - increased synthesis and storage pf triacyl glycerides - insulin inhibits lipolysis (TAGs to fatty acids)
29
what effects does insulin effect on the liver
1. uptake of glucose and conversion to glycogen 2. fatty acid synthesis 3. inhibits glycogenolysis 4. inhibits gluconeogenesis 5. suppresses the formation of ketone bodies (breaking down of fats into ketones)
30
how does insulin effect the uptake of glucose and conversion to glycogen in the liver
entry of glucose into hepatocytes is mainly via GLUT2 which is insulin dependent
31
how does insulin effect fatty acid synthesis in the liver
when the quantity of glucose entering liver cells is more than that can be stored as glycogen (or used for hepatocyte metabolism) then insulin promotes conversion of excess glucose into fatty acids
32
what happens to the excess glucose when it can not be stored
the fatty acids are packaged into VLDL as triglyceride and enters the bloodstream to be transported to other tissues
33
what is glycogenolysis
the breakdown of glycogen to glucose
34
what is gluconeogenesis
the production of new glucose from non-carbohydrate sources eg: - amino acids - glycerol - lactate
35
how is insulin used as a signal to the body that it is full
- by promoting the uptake and storage of nutrients Insulin signals to the body that it's full by facilitating glucose uptake into cells, reducing blood sugar levels, and initiating fat storage
36
how will the body respond when there is no insulin the body
- mobilizing glycogen stores in muscle and liver - breaking down protein to its constituent amino acids which can be used for energy or to make new glucose in the liver - mobilizing fat stores to increase lipid levels in blood - increasing ketone production as it can be used as an energy source for various tissues including the brain
37
what type of hormone is glucagon
a polypeptide hormone
38
where is glucagon secreted
secreted by alpha cells of pancreatic islets
39
what stimulates the secretion of glucagon
secreted in response to hypoglycemia (low blood glucose) or exercise
40
how does glucagon exert its effect
exerts its effect primarily on the liver via activation of receptors that utilize cAMP as a second messenger
41
what are the functions of the enzymes that is activated by glucagon
1. causes breakdown of glycogen to glucose 2. promote production of new glucose by hepatocytes 3. promotes release of glucose from liver cells into blood 4. promote breakdown of triglycerides and release of fatty acids from adipose
42
what is type 1 Diabetes Mellitus
a chronic autoimmune condition where the body's immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas - essentially no insulin production by beta cells
43
what is thought to be the cause of type 1 diabetes mellitus
the autoimmune destruction of pancreatic beta cells, thought to be due to some environmental trigger such as a viral infection combined with genetic predisposition
44
what are some acute symptoms of type 1 diabetes mellitus
- passing urine frequently - very thirsty and drinking lots - excessive hunger - tiredness - weight loss - decreased concentration - mood changes - tummy pain
45
what are chronic effects of type 1 diabetes mellitus
- poor healing - increased infection risk - cardiovascular disease - renal disease - diabetic retinopathy - diabetic neuropathy
46
what is diabetic retinopathy
Diabetic retinopathy is a serious complication of diabetes that affects the retina, the light-sensitive lining at the back of the eye
47
what is diabetic neuropathy
Diabetic neuropathy is a type of nerve damage that can occur in people with diabetes, caused by persistently high blood sugar levels damaging nerves, especially in the legs and feet
48
what is the treatment for type 1 diabetes
insulin - other dietary and exercise management strategies may also be involved
49
what is a risk of the treatment of insulin
the risk of hypoglycemia
50
what symptoms does hypoglycemia have in related to the SNS
- tachycardia - palpations - diaphoresis - tremor - pallor - anxiety
51
what symptoms does hypoglycemia have in related to inadequate blood glucose for normal brain function
- headaches - dizziness - irritability - fatigue - confusion - visual changes - hunger
52
what are 2 modern ways of monitoring blood glucose levels
1. continuous glucose monitors work (CGMs) 2. CGMs coupled to insulin pump
53
how does continuous glucose monitors work (CGMs)
a subcutaneous BGL sensor transmits to device and the person can adjust insulin dose accordingly
54
how does CGMs coupled to insulin pump work
a subcutaneous BGL sensor transmits to the device and the pump algorithm adjusts the infusion rate of insulin accordingly - this can utilize a feedforward and negative feedback system
55
what is type 2 diabetes mellitus
the body has a reduced sensitivity to the effects of insulin - hyposensitivity
56
what are common causes of type 2 diabetes mellitus
- inactivity - poor diet - obesity
57
how does type 2 diabetes mellitus lead to hyposecretion
insulin secretion may be high at the early stages of the disease and later on in the disease the beta cells may be worn out. - leading to progressively lower insulin secretion and worsening blood glucose control
58
what is the treatment for type 2 diabetes
1. aim to reduce weight by 10-15% early on in the disease to achieve remission 2. metformin which improves insulin sensitivity of cells and reduces hepatic gluconeogenesis 3. drugs that cause glucose to be lost in urine (SGLT2 inhibitors) 4. drugs that increase insulin secretion - GLP 1 receptor agonists - sulphonyl urea drugs 5. Acarbose - slows down absorption of glucose in intestines
59
what is polyuria
passing large amounts of urine
60
what is polydipsia
excessive drinking or thirst
61
what is polyphagia
excessive hunger
62
what is gestational diabetes
a condition where a pregnant woman develops high blood glucose levels during pregnancy, usually between 24 and 28 weeks
63
what are other conditions can cause raised blood glucose
- diseases that damage the pancreas such as pancreatitis or cystic fibrosis - some medications such as glucocorticoids

HUBS 191 (34 decks)

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