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HLST128: Physiology II > Chapter: Endocrine Control of GH > Flashcards

Chapter: Endocrine Control of GH Flashcards

1
Q

GH is children causes

A
  • a continuous net protein synthesis
  • increase in lenght, diameter, size, and the number of cells in the soft tissues and long bones
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2
Q

Characteristics of fetal growth

A
  • GH from the fetal pituitary plays NO role in fetal growth (growth facilitated by placenta hormones)
  • genetic and nutritional factors effect fetal growth
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3
Q

postnat growth occurs

A

during the first 2 years of life

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4
Q

pubertal growth occurs

A

during adolescent

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5
Q

Secretion of ______ during pubertal growth increases protein synthesis and bone growth

A

androgen

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6
Q

a marked acceleration in _______________ is due to lengthening of long bones

A

linear growth

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7
Q

________ promotes protein synthesis and bone growth in pubertal boys

A

testosterone

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8
Q

what 2 hormones act on the bones to achieve full adult height by the end of adolescence

A

testosterone and estrogen

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9
Q

what are the 4 factors affecting growth

A
  • genetic factors
  • an adequate diet
  • free chronic diseases and stress
  • normal level of GH hormones
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10
Q

genetic factors

A

determine an individuals maximum growth

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11
Q

adequate diet

A
  • protein and amino acid rich diet
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12
Q

an inadequate diet in infancy and childhood can causes

A

stuning in brain and growth development

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13
Q

___% of total growth occurs in the first 2 years of life

A

70

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14
Q

effect of chronic diseases and stress on growth

A
  • cortisol acts as an anti-growth hormone by protein breakdown (protein degration), inhibiting the growth of long bones and GH secretion
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15
Q

what other hormones effect GH secretion

A

thyroid, sex hormones, and insulin

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16
Q

bone thickness

A
  • achieved by adding new bone cells by osteoblast tot the periosteum (bones outer surface)
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17
Q

Bone growth (linear growth)

A
  • caused by division (proliferation) and multiplication of chondrocytes on the outer edge of the epiphyseal plate
  • enlargement of chondrocytes in the diaphysis widens the epiphyseal plate
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18
Q

4 metabolic effects of GH

A
  • increases the rate of protein synthesis
  • increased fatty acid mobilization by adipose tissue degration and increases fatty acid use by the body
  • decrease rate of glucose uptake by body tissues (increases blood glucose levels)
  • increase glucose output by the liver
19
Q

GH promotes the growth of soft tissues and the skeleton by,

A
  • hyperplasia
  • hypertrophy
20
Q

hyperplasia

A

increases the number of cells

21
Q

hypertrophy

A

increases the size of cells

22
Q

Growth promoting actions of GH on soft tissues

A
  • increases size of cells by cell division
  • prevents apoptosis (programmed cell death)
  • increases protein synthesis (uptake amino acids by cells)
  • stimulates the cellular machinery according to genetic code to accomplish protein synthesis
23
Q

feedback of GH

A

Negative feedback

hypothalamus –> hypophysiotrophic hormones (GHRH/GHIH)–> anterior pituitary –> target tissues/endocrine gland

24
Q

Somatomedin / insulin-like growth factor (IGF-1)

A
  • acts directly on bones and soft tissues to bring about most growth promoting actions
  • stimulates protein synthesis, cell division, lengthening, and thickening of bones
  • increases fatty acid levels in the blood by enhancing triglyceride / fat storage breakdown in the adipose tissue
  • increases blood glucose levels by decreasing glucose uptake by muscles
25
Q

IGF-2 functions

A
  • does not depend on GH level
  • important in fetal development
  • role in adults is unclear
26
Q

what are the 3 factors that control IGF-1 production

A
  • nutrition
  • age
  • various tissue-specific stimulating factors
27
Q

nutrition effect on IGF-1

A
  • inadequate food intakw decreases IGF-1 levels through sensitivity to GH in the tissue that produces IGF-1
  • EXAMPLE: fasting decreases IGF-1 levels but increases GH secretion
28
Q

Age effect on IGF-1

A

a dramatic increase in circulating IGF-1 levels accompanies the moderate increase in GH at puberty

29
Q

various tissue specific stimulating facts effect on IGF-1

A
  • increase IGF-1 production in a particular tissue
30
Q

Example on how various tissue specific stimulating facts effects IGF-1

A

gonadatropin and sex hormones stimulate IGF-1 in the testes, the ovaries and the uterus (fetal development)

31
Q

What are the 4 factors that influence GH secretion

A
  • GHRH/GHIH
  • Diurnal rhythms
  • excercise, stress, and hypoglycemia
  • amino acids
32
Q

GHRH/GHIH effect on Gh secretion

A
  • antagonistic factors that control GH secretion
  • negative feedback loop
  • somatomedins (liver) influence the anterior pituitary to inhibit the effects of GHRH an Gh release
33
Q

Diurnal rhythms effect on GH secretion

A
  • GH levels tend to be low and constant for most of the day
  • Gh levels are 5 times higher after one hour of deep sleep and drops over several hours throughout the day
34
Q

Amino acids effect on GH secretion

A
  • increasing the amino acid level after a high protein meal increases GH secretion
  • a decrease in blood fatty acid stimulates GH release
35
Q

cause of dwarfism

A
  • lack of GH from the anterior pituitary in a child
  • lack of growth hormone-releasing hormones from the hypothalmus
36
Q

Dwarfism symptoms

A
  • hyposecretion of GH in childhood
  • poorly developed musculature
  • excessive subcutaneous fat (less fat mobalized)
37
Q

Laron Dwarfism

A
  • failure of tissue to respond to GH (receptors are unresponsive)
  • reduced skeletal muscle mass and decreased bone density in adults
  • risk of developing heart failure
38
Q

Gigantism

A
  • tumor of GH producing cells in the anterior pituitary
  • overproduction of GH in childhood before the epiphyseal plate closes
  • individual may reach a high of 8ft or more
39
Q

Acromegaly casues

A
  • hypersecretion of GH after adolescence before the epiphyseal plate close, further growth in height is prevented
40
Q

Acromegaly symptoms

A
  • thickening of soft tissues (skin and bones become thick in the extremities and face)
  • jaw and cheekbone can fuse, giving ape-like appearance
  • hands and feet enlarge, and fingers and toes become thick
  • peripheral nerve disorder may occur from overgrown connective tissues that trap nerves
  • may result in visual disturbances
41
Q

thyroid hormone role in growth

A
  • essential for normal growth but does not promote growth
  • plays a permissive role in skeletal growth
42
Q

children whom experience hypothryroidism exhibit

A

stunted growth

43
Q

insulin effect on growth

A
  • serves as a growth promotor
  • Hyperinsulinemia increases growth and deficiency reverses it
  • it may excert its effects via IGF-1 receptors as both receptors appear to be similar structurally
44
Q

Androgens (testosterone and estrogen) effect on growth

A
  • powerfully stimulate protein synthesis
  • promotes linear growth, body weight and muscle mass
  • testicular androgen developes heavier musculature in males
  • androgenic growth promoting effects are exerted through GH
  • estrogen terminates linear growth by stimulating the conversion of the epiphyseal plate to bone

HLST128: Physiology II (14 decks)

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