Chapter: Endocrine Control of GH Flashcards
GH is children causes
- a continuous net protein synthesis
- increase in lenght, diameter, size, and the number of cells in the soft tissues and long bones
Characteristics of fetal growth
- GH from the fetal pituitary plays NO role in fetal growth (growth facilitated by placenta hormones)
- genetic and nutritional factors effect fetal growth
postnat growth occurs
during the first 2 years of life
pubertal growth occurs
during adolescent
Secretion of ______ during pubertal growth increases protein synthesis and bone growth
androgen
a marked acceleration in _______________ is due to lengthening of long bones
linear growth
________ promotes protein synthesis and bone growth in pubertal boys
testosterone
what 2 hormones act on the bones to achieve full adult height by the end of adolescence
testosterone and estrogen
what are the 4 factors affecting growth
- genetic factors
- an adequate diet
- free chronic diseases and stress
- normal level of GH hormones
genetic factors
determine an individuals maximum growth
adequate diet
- protein and amino acid rich diet
an inadequate diet in infancy and childhood can causes
stuning in brain and growth development
___% of total growth occurs in the first 2 years of life
70
effect of chronic diseases and stress on growth
- cortisol acts as an anti-growth hormone by protein breakdown (protein degration), inhibiting the growth of long bones and GH secretion
what other hormones effect GH secretion
thyroid, sex hormones, and insulin
bone thickness
- achieved by adding new bone cells by osteoblast tot the periosteum (bones outer surface)
Bone growth (linear growth)
- 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
4 metabolic effects of GH
- 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
GH promotes the growth of soft tissues and the skeleton by,
- hyperplasia
- hypertrophy
hyperplasia
increases the number of cells
hypertrophy
increases the size of cells
Growth promoting actions of GH on soft tissues
- 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
feedback of GH
Negative feedback
hypothalamus –> hypophysiotrophic hormones (GHRH/GHIH)–> anterior pituitary –> target tissues/endocrine gland
Somatomedin / insulin-like growth factor (IGF-1)
- 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