Lecture 21 3/7/24

Question 1

What are the main secretory products of the endocrine pancreas?

Answer 1

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

Question 2

Which molecule is produced by pancreatic delta cells?

Answer 2

somatostatin

Question 3

Which molecule is produced by PP cells?

Answer 3

pancreatic peptide

Question 4

Which molecules are secreted by enterochromaffin cells?

Answer 4

-serotonin
-substance P

Question 5

What are the potential sources for glucose?

Answer 5

-food (exogenous)
-glycogen (endogenous)

Question 6

Which element is needed for glucose absorption?

Answer 6

Na+

Question 7

What can potentially form glucose?

Answer 7

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

Question 8

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

Answer 8

D-glucose

Question 9

What are the characteristics of the liver and glucose homeostasis?

Answer 9

-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

Question 10

What process is driven by glucagon?

Answer 10

glycogenolysis

Question 11

What process is driven by insulin?

Answer 11

glycogenesis

Question 12

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

Answer 12

-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

Question 13

Which enzymes are most important for glycogen synthesis?

Answer 13

-hexokinase
-glycogen synthase

Question 14

What are the characteristics of glucokinase?

Answer 14

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

Question 15

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

Answer 15

-glycogen phosphorylase
-glucose-6-phosphatase

Question 16

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

Answer 16

-increases glycogen synthase activity
-inhibits glycogen phosphorylase activity

Question 17

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

Answer 17

-increases glycogen phosphorylase activity
-inhibits glycogen synthase activity

Question 18

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

Answer 18

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

Question 19

What range of blood glucose is seen in diabetes?

Answer 19

200-700 mg/dl

Question 20

What blood glucose level indicates hypoglycemia?

Answer 20

40 mg/dl or less

Question 21

Why does starvation not cause a dramatic drop in glucose?

Answer 21

liver glycogen can provide glucose for up to 12 hours

Question 22

Which hormones are hyperglycemic hormones?

Answer 22

-GH
-cortisol
-catecholamines
-glucagon

Question 23

Which hormone is a hypoglycemic hormone?

Answer 23

insulin

Question 24

What are the physiologic causes of hyperglycemia?

Answer 24

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

Question 25

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

Answer 25

-catecholamines -GH

Question 26

Which hormone is involved with stress-associated hyperglycemia?

Answer 26

cortisol

Question 27

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

Answer 27

-progesterone -estradiol

Question 28

What is fructosamine?

Answer 28

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

Question 29

Why is fructosamine used to detect hyperglycemia?

Answer 29

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

Question 30

What is glycated hemoglobin?

Answer 30

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

Question 31

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

Answer 31

magnitude and duration of hyperglycemia

Question 32

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

Answer 32

degradation/loss of the parent molecule

Question 33

What is the effect of glucose on beta cells?

Answer 33

stimulates beta cells, leading to insulin secretion

Question 34

What is the effect of insulin of alpha cells?

Answer 34

insulin inhibits alpha cells

Question 35

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

Answer 35

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

Question 36

How does insulin affect muscle?

Answer 36

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

Question 37

How does insulin affect adipose tissue?

Answer 37

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

Question 38

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

Answer 38

GLUT4

Question 39

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

Answer 39

secondary active transport of sodium and glucose

Question 40

What is the role of GLUT 1 through 7?

Answer 40

diffusion of glucose into various tissues

Question 41

Which GLUT is the only one that is insulin dependent?

Answer 41

GLUT4

Question 42

What is the role of PIP3?

Answer 42

determines the ability of vesicles to fuse/internalize

Question 43

What is the role of hormone sensitive lipase?

Answer 43

breaks down triacylglycerol into free fatty acids and glycerol

Question 44

How does insulin inhibit hormone sensitive lipase?

Answer 44

decreasing synthesis of cAMP at the adenylate cyclase

Question 45

What is considered severe hypoglycemia?

Answer 45

glucose concentration fluctuates between 15 and 50 mg/dl

Question 46

What is considered mild hypoglycemia?

Answer 46

glucose concentration fluctuates between 60 and 70 mg/dl

Question 47

What signs are associated with severe hypoglycemia?

Answer 47

-neuroglucopenia -disorientation -convulsion -unconsciousness -shock

Question 48

What signs are associated with mild hypoglycemia?

Answer 48

-sympathoadrenal signs -nervousness -tremor -weakness -sweating

Question 49

What are the stimulatory effects of glucagon and epi?

Answer 49

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

Question 50

What are the stimulatory effects of GH and cortisol?

Answer 50

-interfere with glucose uptake by muscle and fat

Question 51

What are the characteristics of GLUT 1 and 3?

Answer 51

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

Question 52

How do insulin and leptin act on the hypothalamus?

Answer 52

-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

Question 53

How does hypoglycemia impact the adrenal medulla?

Answer 53

activates autonomic nervous system and stimulates epinephrine and norepinephrine release