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Patho 2 > 1 - Insulin and Glucagon > Flashcards

1 - Insulin and Glucagon Flashcards

1
Q

The pancrease aids in glucose control by secreting which two hormones:

A

glucagon

insulin

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2
Q

What are the two major types of tissues in the pancreas?

A
  1. Acini - secrete digestive juices into the duodenum
  2. Islets of langerhans - secrete insulin and glucagon directly into the blood
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3
Q

Describe the three major types of islet cells:

A
  1. Alpha - 25%, secrete glucagon
  2. Beta - 60%, secrete insulin and amylin
  3. Delta - 10%, secrete somatostatin
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4
Q

In the pancreas, cell-to-cell communication leads to control of secretion.

Insulin inhibits ______

Amylin inhibits _______

Somatostatin inhibits ________

A

glucagon secretion

insulin secretion

insulin and glucagon secretion

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5
Q

Insulin effects the metabolism of ______

A

protein, fat, AND carbohydrate metabolism

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6
Q

Human insulin is composed of two amino acid chains connected by _______

A

disulfide linkages

When the two AAs are split apart, insulinf’s functional activity is lost

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7
Q

In a patient who is taking insulin to control their glucose, how can you tell how much insulin their pancreas is producing?

A

Checking C peptide levels by radioimmunoassay

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8
Q

What is the halflife of endogenous insulin?

A

6 minutes

cleared within 15 minutes

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9
Q

What happens when insulin binds with its receptor on a cell?

A

within seconds the membrane increases the uptake of glucose (EXCEPT IN NEURONS)

the cell membrane becomes more permeable to amino acids, K, and Phos

Prolonged changes take place due to DNA transcription activation

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10
Q

When exercising, how do your muscle cells increase their glucose uptake?

A

When they contract it mobilizes GLUT 4 from intracellular storage to the depot, which increases glucose permeability

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11
Q

After eating, large amount of glucose is moved into the muscles. What happens to this glucose, assuming you don’t immediately exercise?

A

stored as muscle glycogen , which can be used later by the muscle for energy

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12
Q

Insulin causes most of the glucose absorbed after a meal to:

A

be rapidly stored in the liver as glycogen

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13
Q

Describe how insulin causes glucose uptake by the liver

A
  1. activates liver phosphorylase to stop any further breakdown of glycogen
  2. increases the activity of glucokinase, which phosphorylates glucose as it enter the cell so that it’s trapped inside the cell
  3. increases the activities of glycogen synthase to polymerize the units into glycogen
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14
Q

When blood sugar falls, how does glucose get released back into the blood from the liver?

A

by decreased amount of insulin

pancrease stops secreting insulin and the liver stops inhibiting glucose breakdown

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15
Q

What happens when the amount of glucose consumed is more than can be stored in the liver as glycogen?

A

insulin promotes the conversion of glucose into fatty acids

fatty acids are packaged as LDLs

LDLs are transported to the adipose tissue and deposited as fat

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16
Q

Which organ has a glucose level that is completely unaffected by insulin?

A

The brain!

Most brain cells are permeable to glucose and can use glucose without the intermediation of insulin

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17
Q

Why does insulin increase fat storage?

A

Insulin increases glucose use, which means less fat is used for energy

promotes fatty acid synthesis

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18
Q

What effect does insulin have on protein formation?

A

promotes formation

prevents degradation

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19
Q

An insulin deficiency has what effect on plasma fatty acids?

Plasma amino acids?

A

Increased (since glucose can’t be used)

Increased (more protein being broken down in the absence of insulin)

20
Q

Insulin acts synergistically with ________ to promote growth

A

growth hormone

21
Q

How do beta cells know when to secrete insulin?

A

have a large number of glucose transporters that keep glucose influx into the cell proportional with serum blood glucose levels

when glucose is phosphorylated in the cell if gets stuck and triggers closure of potassium channels

closing the K channels depolarizes the membrane, which causes an influx of calcium

calcium triggers vessicular release of insulin

22
Q

How do sulfonylureas work?

A

stimulate insulin secretion by binding to the ATP-sensitive potassium channels (the same ones glucose binds to) in order to cause depolarization

depolarization releases insulin

23
Q

What are incretins?

A

hormones that enhance the rate of insulin release from pancreatic beta cells

also inhibit glucagon release from alpha cells

24
Q

prolonged secretion of which hormones can cause exhaustion of beta cells?

A

glucagon

GH

cortisol

progesterone and estrogen

25
Q

Stimulation of the ______ nerves to pancrease can increase insulin secretion

A

parasympathetic

26
Q

What is the effect of epinephrine on blood glucose levels?

A

causes glycogenolysis in the liver, releaseing large quantities of glucose into the blood

breaks down adipose cells and increases concentration of fatty acids

27
Q

Glucagon is also called the ________ hormone

A

hyperglycemic

28
Q

What is remarkable about the glycogenolysis pathway sparked by glucagon?

A

one of the most thoroughly studied examples of adenylyl cyclase - cAMP pathway

amplifying effect: each succeeding product of the pathway is produced in greater quantity than the preceding product

29
Q

Glucagon raises blood sugar via _______ and _______

A

glycogenolysis in the lvier

gluconeogenesis in the liver after all available glycogen stores are utilized

30
Q

Why is glucagon helpful in beta blocker overdose?

A

It increases heart rate and myocardial contractility by some mechanism other than the B1 recceptor that somehow bypases the need for beta receptor activation

31
Q

An increase in blood glucose ______ glucagon

Increased blood amino acids ______ glucagon

Exercise ______ glucagon

A

decreases

increases

increases

32
Q

What is the principle role of somatostatin?

A

extend the period over which food nutrients are assimilated into the blood

prevents rapid exhaustion of the food

33
Q

Somatostatin is also the same chemical substance as _____

A

growth hormone inhibition hormone

Makes sense, since insulin and GH have dual roles in promoting growth

34
Q

In severe hypoglycemia, low blood sugar in the cells of the ________ stimulates the SNS to release _______

A

hypothalamus

epinephrine from the adrenal cortex

35
Q

Which organs rely on glucose ONLY and cannot use fats for metabolism?

A

the brain

retina

germinal epithelium of the gonads

36
Q

Type 1 DM is associated with _____ insulin levels

Type 2 DM is associated with ______ insulin levels

A

decreased

increased

37
Q

Why does obesity cause insulin resistance?

A

Likely isn’t due to a decreased number of insulin receptors, but rather an alteration in secondary signalling

likely that toxic lipid accumulation in cells causes this abnormal signalling

38
Q

What are SgLT2 inhibitors?

A

Inhibit SGLT2 in the renal tubules, preventing reabsorption of glucose

39
Q

HbA1c is useful for testing glucose levels over past three months. Why?

A

lifespan of a RBC is 120 days

40
Q

Why is it problematic to try to just cut out carbs for patients with DM2?

A

It keeps BG low, but a lack of insulin still causes increased LDLs and protein deficiency.

It’s recommended to give diabetics a normo-carb diet and give enough insulin to cover the carbs eaten

41
Q

______ calcium causes nervous excitability

_______ calcium causes nervous depression

A

decreased

increased

42
Q

The anterior lobe of the pancreas, where endocrine action is most profound, is perfused by:

The posterior lob is perfused by:

A

superior mesenteric A

celiac A

43
Q

Insulin facilitates the intracellular transport of which three ions:

A

potassium

phosphate

magnesium

44
Q

What is amylin

A

cosecreted with insulin

regulates BG conentration by delaying gastric emptying and suppressing glucagon secretion after meals

satiety effect

ANTI-HYPERGLYCEMIC

45
Q

How do glucose levels effect glucagon release?

A

high glucose –> decreased glucagon

low glucose -> increased glucagon

46
Q

What is the difference between hypothalamic somatostatin and pancreatic somatostatin?

A

P somatostatin regulates islet cell function to inhibit secretion of insulin, glucagon, and polypeptide

essential in carbohydrate, fat, and protein metabolism

H somatostatin inhibits release of GH and TSH

47
Q

Somatostatin has what effect on somatotropes?

A

Keeps them “static”

(inhibits)

Patho 2 (24 decks)

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