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Physiology > Exam 3: Ch 19 Regulation of Metabolism > Flashcards

Exam 3: Ch 19 Regulation of Metabolism Flashcards

1
Q

Pancreatic Islets of Langerhans

A
  • Contain 2 cell types involved in energy homeostasis:
    • a cells
    • b cells
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2
Q

a cells

A
  • secrete glucagon
    • when glucose levels are low,
    • causes increased glucose by stimulating glycogenolysis in liver
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3
Q

b cells

A
  • secrete insulin
    • when glucose levels are high
    • reduces blood glucose by promoting its uptake by tissues
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4
Q

Normal fasting glucose level

A

65–105 mg/dl

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5
Q

After a meal is absorbed, blood glucose levels

A
  • rise to ~ 140 – 150 mg/dl

- This rise stimulates secretion of insulin and inhibits glucagon secretion

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6
Q

Insulin & glucagon normally prevent

A

levels from rising above 170mg/dl after meals or falling below 50mg/dl between meals

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7
Q

Insulin Overall effect is to promote

A

anabolism

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8
Q

anabolism

A
  • Promotes storage of digestion products (not only glucose)
  • Inhibits breakdown of fat & protein
  • Inhibits secretion of glucagon
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9
Q

Insulin: Anabolism stimulates

A

insertion of GLUT4 transporters (transport by facilitated diffusion) in cell membrane of skeletal muscle, liver, & fat

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10
Q

Oral Glucose Tolerance Test

A
  • Assesses ability of b cells to secrete insulin & insulin’s ability to lower blood glucose
  • Responses to drinking a glucose solution are measured
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11
Q

Oral Glucose Tolerance Test

in non-diabetics

A

glucose levels return to normal within 2 hrs

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12
Q

Oral Glucose Tolerance Test

in diabetics

A

Diabetes mallitus causes blood glucose >200 mg/dl after 2 hrs

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13
Q

Glucagon

A
  • Maintains blood glucose concentration above 50mg/dl
  • Stimulates glycogenolysis in liver
  • Stimulates gluconeogenesis, lipolysis, & ketogenesis
    • Skeletal muscle, heart, liver, & kidneys use fatty acids for energy
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14
Q

Effects of ANS on Insulin & Glucagon

A

ANS innervates islets

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15
Q

Activation of parasympathetic NS

A

stimulates insulin secretion

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16
Q

Activation of sympathetic NS

A

NS stimulates glucagon & inhibits insulin

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17
Q

Effects of Intestinal Hormones

A

Insulin levels increase more rapidly after glucose ingestion than after intravenous glucose infusion

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18
Q

after intravenous glucose infusion

due to hormones secreted by intestine during meals

A
  • “in anticipation” of glucose rise: all stimulate insulin secretion
  • GIP; GLP-1; CCK
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19
Q

GIP

A

= gastric intestine peptide (secreted by duodenum),

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20
Q

GLP-1

A

= glucagon-like peptide (secreted by ileum),

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21
Q

CCK

A

= cholecystokinin

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22
Q

Diabetes mallitus

A

characterized by chronic high blood glucose levels (hyperglycemia)

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23
Q

hyperglycemia

A

the major cause of kidney failure and amputations, and is the 2nd leading cause of blindness

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24
Q

Type I (insulin dependent or IDDM)

A
  • due to insufficient insulin secretion by beta cells
  • 5 – 10% of total cases
  • requires exogenous insulin
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25
Q

Type II (insulin independent or NIDDM)

A
  • due to lack of efficiency of insulin at target cells

- 90 – 95% of total cases

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26
Q

Type 1diabetes (formerly “juvenile on set”)

A

= b cells of islets are destroyed by autoimmune attack, thus beta cells secrete little or no insulin

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27
Q

Glucose is unable to enter resting muscle or adipose cells

A

–> rate of fat synthesis lags behind rate of lipolysis –> fatty acids are converted to ketone bodies, leading to ketosis (↑ [ketone] in blood) producing ketoacidosis (↓ pH) –> glucose and ketones in urine (glucosuria or ketonuria) + ↑ H2O excretion because glucose and ketones act like osmotic diuretics (severe dehydration)

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28
Q

–> ↑ glucagon levels stimulate

A

glycogenolysis in liver, which ↑ [glucose] in blood also ↑ [ketone] in blood–>serious electrolyte imbalances–> coma or death

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29
Q

Type II diabetes

A

due to lack of efficiency of insulin at target cells)=

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30
Q

Type II diabetes slow to develop

A

heredity plays a role and occurs most often in overweight people

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31
Q

Type II diabetes involves

A

insulin resistance; usually accompanied by normal-to-high insulin levels

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32
Q

Type II diabetes treatable by

A
  • exercise & diet
    • b/c being over weight causes insulin resistance, thus ↑ caloric expenditure and shrinking fat cells ↑ insulin responsiveness
  • Is not usually accompanied by ketoacidosis
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33
Q

Hypoglycemia

A

abnormally low blood [glucose]

34
Q

Reactive hypoglycemia

A

is over secretion of insulin due to an exaggerated response of  cells to a rise in glucose

35
Q

Hypoglycemia

occurs in

A

people who are genetically predisposed to type II diabetes

36
Q

Hypoglycemia controlled by

A

eating less carbohydrates and eating many small meals throughout the day

37
Q

Hypoglycemia symptoms

A

include tremors, hunger, weakness, blurred vision, & confusion

38
Q

Anabolic effects of insulin are antagonized by

A

Glucagon

39
Q

(catecholamines) epinephrine and norepinephrine are made by

A

the adrenal medulla in response to sympathetic innervation

40
Q

The actions of epinephrine and norepinephrine are similar to

A
  • glucagon,

- stimulating glycogenolysis (release of glucose from liver), & lipolysis (release of fatty acids from adipose)

41
Q

Adrenal Hormones - Metabolic Effects of Epinephrine & Norepinephrine

  • glucagon is released during
A
  • fasting to ↑ blood [glucose] and during the flight or flight response,
  • epinephrine and norepinephrine are released to ↑ blood [glucose]
42
Q

cortisol (a glucocorticoid) is made by

A

the adrenal cortex in response to sympathetic innervation

43
Q

Cortisol is secreted

A

response to ACTH from Ant. Pit.

44
Q

ACTH is often released in

A

response to stress, including fasting & exercise where it supports effects of glucagon

45
Q

Cortisol promotes

A

lipolysis, ketogenesis, & protein breakdown (in muscles) –> Protein breakdown increases amino acid levels for use in gluconeogenesis in liver

46
Q

Thyroid secretes mostly

A 
inactive tetraiodothyronine (thyroxine =T4
in response to TSH from Ant. Pit.
47
Q

basal metabolic rate = BMR is determined by

A

physical activity, eating, and HEAT

48
Q

T3 helps set BMR by

A
  • regulating cell respiration and heat;

- also necessary for growth & development, especially of CNS

49
Q

T3 produces

A

uncoupling proteins (like those in brown fat) so↓ [ATP] controls BMR b/c stimulates heat production via [ATP] ↓, cellular respiration ↑, thus thyroxine ↑ metabolic heat (calorigenic effect)

50
Q

BMR is essential for

A

cold adaptation

51
Q 
Growth Hormone (GH) Secretion
- GH (somatotropin) is from
A

Ant. Pit.

stimulated by ↓ blood [glucose] and ↑ [aa] via GHRH (from hypothalamus)

52
Q

GH (somatotropin) stimulates

A

growth in children & adolescents

53
Q

GH (somatotropin) Has important metabolic effects in adults

A
  • is increased during fasting
  • stimulates protein synthesis
  • stimulates fat breakdown
  • decreases glucose use by most tissues b/c of ↓ rates of glycolysis due to ↑ lypolysis
54
Q

Insulin-like Growth Factors (IGFs)

A

IGFs are similar to pro-insulin

produced by many tissues

55
Q

Insulin-like Growth Factors (IGFs)

are called

A

somatomedins because mediate many of GH’s effects

56
Q

Insulin-like Growth Factors (IGFs) examples

A
  • Ex. Liver produces & secretes IGF-1 in response to GH; IGF-1 in turn stimulates cell division & growth of cartilage
  • These actions are supported by IGF-2 which has more insulin-like actions
57
Q

Parathyroid hormone, 1,25-dihydoxyVit D, & calcitonin control

A
  • Ca2+ and P043- (phosphate) levels & activities

- via effects on bone formation & reabsorption, intestinal absorption, & urinary excretion

58
Q

Skeleton is a storage reservoir for

A

for Ca2+ & PO43-

59
Q

Bone is hardened with

A

calcium phosphate crystals (hydroxyapatite)

60
Q

Osteoblasts

A

make bone in response to calcitonin

61
Q

Osteoclasts

A

resorb bone in response to PTH

62
Q 
Parathyroid Hormone (PTH) and Bone
- PTH is secreted by
A

by parathyroid glands

- is most important hormone in control of Ca2+ levels

63
Q

PTH release is stimulated by

A

low blood Ca2+ levels

64
Q

PTH stimulates

A
  • Stimulates osteoclasts to reabsorb bone

- Stimulates kidneys to reabsorb Ca2+ from filtrate, & inhibits reabsorption of P043-

65
Q

PTH Promotes formation of

A

1,25 Vit D3

66
Q

Many cancers secrete

A

PTH-related protein that interacts with PTH receptors producing hypercalcemia

67
Q

hypocalcemia

A
  • Too little PTH
  • causes tetanus b/c it increases membrane permeability to Na+
    • over excitation of neurons and muscle fibers
68
Q

Calcitonin

A
  • secreted by C cells of thyroid gland

- works with PTH & 1,25 Vit D3 to regulate blood Ca2+ levels

69
Q

Calcitonin stimulated by

A

increased plasma Ca2+

70
Q

Calcitonin Inhibits

A

activity of osteoclasts

71
Q

Calcitonin stimulates

A
  • urinary excretion of Ca2+ & P043- by inhibiting reabsorption
    • Physiological significance in adults is not understood
72
Q

Estrogen, Testosterone, & Bone

  • Estrogen causes
A

epiphyseal discs (cartilaginous growth plates) to seal (ossify) which stops growth (in both men and women)

73
Q

Estrogen is made in

A

in ovaries (women) and in the epiphyseal discs from circulating testosterone (men)

74
Q

Estrogen is necessary for

A
  • is necessary for proper bone mineralization

- is necessary for prevention of osteoporosis

75
Q

post menopausal women have ↓ [estrogen] b/c

A

↓ ovarian action but men can make it in bone

76
Q

Estrogen stimulates

A

osteoblast activity & suppresses formation of osteoclasts

77
Q

TSH & Thyroxine

- Hyperthyroids are more prone to

A
  • osteoporosis

- Not well understood, but osteoblasts & osteoclasts have receptors for T3

78
Q

1,25 Vitamin D3 Synthesis begins in

A

skin in response to by sunlight and continues in the kidneys, where cholesterol derivative is converted to Vit D3

79
Q

1,25 Vitamin D3 Synthesis stimulated by

A

PTH

80
Q

1,25 Vitamin D3 directly stimulates

A

intestinal absorption of Ca2+ & P043-, when Ca2+ intake is inadequate, directly stimulates bone resorption

81
Q

1,25 Vitamin D3 stimulates kidney to

A

reabsorb Ca2+ and P043; simultaneously raising Ca2+ & P043- results in increased tendency of these to precipitate as hydroxyapatite

82
Q

Inadequate Vit D in diet & body causes

A

osteomalacia (adults) & rickets (children) = loss of bone calcification

Physiology (27 decks)

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