Lecture 21 3/7/24 Flashcards

1
Q

What are the main secretory products of the endocrine pancreas?

A

-insulin (prod. by beta cells)
-glucagon (prod. by alpha cells)

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2
Q

Which molecule is produced by pancreatic delta cells?

A

somatostatin

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3
Q

Which molecule is produced by PP cells?

A

pancreatic peptide

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4
Q

Which molecules are secreted by enterochromaffin cells?

A

-serotonin
-substance P

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5
Q

What are the potential sources for glucose?

A

-food (exogenous)
-glycogen (endogenous)

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6
Q

Which element is needed for glucose absorption?

A

Na+

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7
Q

What can potentially form glucose?

A

-glycogen
-glucogenic amino acids
-glycerol
-propionate (ruminants)

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8
Q

What is the principal product of carb. digestion and principal circulating sugar?

A

D-glucose

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9
Q

What are the characteristics of the liver and glucose homeostasis?

A

-liver takes up glucose and coverts it to glycogen and fatty acids
-liver glycogen is broken down to glucose via glucagon and catecholamines
-liver mass sustains glycemia

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10
Q

What process is driven by glucagon?

A

glycogenolysis

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11
Q

What process is driven by insulin?

A

glycogenesis

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12
Q

Why is it important that the liver contains glucose-6-phosphatase, but the brain and muscle do not?

A

-this enzyme allows for release of glucose into blood
-liver drives blood levels of glucose
-muscle and brain want to keep glucose and use it

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13
Q

Which enzymes are most important for glycogen synthesis?

A

-hexokinase
-glycogen synthase

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14
Q

What are the characteristics of glucokinase?

A

-hexokinase found in liver and pancreas
-higher activity when glucose concentrations are higher compared to other hexokinases

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15
Q

Which enzymes are involved in the release of glucose into the blood from glycogen?

A

-glycogen phosphorylase
-glucose-6-phosphatase

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16
Q

How does insulin impact the enzymes that function in glucose storage and release?

A

-increases glycogen synthase activity
-inhibits glycogen phosphorylase activity

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17
Q

How does glucagon impact the enzymes that function in glucose storage and release?

A

-increases glycogen phosphorylase activity
-inhibits glycogen synthase activity

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18
Q

What are the normal ranges for glucose in the blood in animals?

A

domestic animals: 60-120 mg/dl
ruminants: 40-80 mg/dl

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19
Q

What range of blood glucose is seen in diabetes?

A

200-700 mg/dl

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20
Q

What blood glucose level indicates hypoglycemia?

A

40 mg/dl or less

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21
Q

Why does starvation not cause a dramatic drop in glucose?

A

liver glycogen can provide glucose for up to 12 hours

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22
Q

Which hormones are hyperglycemic hormones?

A

-GH
-cortisol
-catecholamines
-glucagon

23
Q

Which hormone is a hypoglycemic hormone?

A

insulin

24
Q

What are the physiologic causes of hyperglycemia?

A

-postprandial/after meal
-excitement/fright
-stress-associated
-estrus/diestrus

25
Q

Which hormones are involved in hyperglycemia due to excitement/fright?

A

-catecholamines
-GH

26
Q

Which hormone is involved with stress-associated hyperglycemia?

A

cortisol

27
Q

Which hormones are involved in estrus/diestrus-related hyperglycemia?

A

-progesterone
-estradiol

28
Q

What is fructosamine?

A

ketoamine formed from the irreversible non-enzymatic linking of glucose to albumin

29
Q

Why is fructosamine used to detect hyperglycemia?

A

the half-life of fructosamine is around 2-3 weeks, and therefore indicates longer term hyperglycemia

30
Q

What is glycated hemoglobin?

A

non-enzymatic addition of glucose to hemoglobin, with a half-life of 2-3 months

31
Q

What is the formation of ketoamines in the blood positively correlated with?

A

magnitude and duration of hyperglycemia

32
Q

What does the removal of ketoamines from the blood depend on?

A

degradation/loss of the parent molecule

33
Q

What is the effect of glucose on beta cells?

A

stimulates beta cells, leading to insulin secretion

34
Q

What is the effect of insulin of alpha cells?

A

insulin inhibits alpha cells

35
Q

What is the mechanism of action of glucose on a beta cell?

A

-glucose enters beta cell via GLUT2 ->
-glucose metabolism increases ATP ->
-ATP closes K+ channels ->
-membrane depolarization ->
-opening of Ca2+ channels ->
-Ca2+ influx ->
-insulin secretion

36
Q

How does insulin affect muscle?

A

-stimulates uptake of K+
-stimulates uptake of glucose -> glycogen synthesis
-stimulates uptake of AAs -> protein synthesis

37
Q

How does insulin affect adipose tissue?

A

-stimulates uptake of K+
-stimulates uptake of glucose -> synthesis of glycerol, fatty acids, and triglycerides

38
Q

Which transporter is used for glucose in muscle and adipose tissue?

A

GLUT4

39
Q

What is the role of sodium-glucose linked transporter (SGLT) 1 and 2?

A

secondary active transport of sodium and glucose

40
Q

What is the role of GLUT 1 through 7?

A

diffusion of glucose into various tissues

41
Q

Which GLUT is the only one that is insulin dependent?

A

GLUT4

42
Q

What is the role of PIP3?

A

determines the ability of vesicles to fuse/internalize

43
Q

What is the role of hormone sensitive lipase?

A

breaks down triacylglycerol into free fatty acids and glycerol

44
Q

How does insulin inhibit hormone sensitive lipase?

A

decreasing synthesis of cAMP at the adenylate cyclase

45
Q

What is considered severe hypoglycemia?

A

glucose concentration fluctuates between 15 and 50 mg/dl

46
Q

What is considered mild hypoglycemia?

A

glucose concentration fluctuates between 60 and 70 mg/dl

47
Q

What signs are associated with severe hypoglycemia?

A

-neuroglucopenia
-disorientation
-convulsion
-unconsciousness
-shock

48
Q

What signs are associated with mild hypoglycemia?

A

-sympathoadrenal signs
-nervousness
-tremor
-weakness
-sweating

49
Q

What are the stimulatory effects of glucagon and epi?

A

-activate hepatic glycogenolysis
-leads to more glucose for brain and heart

50
Q

What are the stimulatory effects of GH and cortisol?

A

-interfere with glucose uptake by muscle and fat

51
Q

What are the characteristics of GLUT 1 and 3?

A

-insulin-independent
-GLUT 3 has higher affinity for glucose than any other GLUT; good for low glucose levels

52
Q

How do insulin and leptin act on the hypothalamus?

A

-inhibit neuropeptide Y production while promoting alpha-MSH and gamma-MSH production
-inhibition of NPY prevents activation of hypothalamus hunger center
-aMSH and yMSH stimulate satiety center

53
Q

How does hypoglycemia impact the adrenal medulla?

A

activates autonomic nervous system and stimulates epinephrine and norepinephrine release