Growth and development Flashcards
prenatal development stages
Ovum
Embryonic
Fetal
Ovum Phase
Shortest phase
cleavage-massive increase in cell # and decrease in cell size
increase in DNA, with no protein synthesis
Embryonic phase
formation of ectoderm, mesoderm, and endoderm
starts to take form
Fetal phase
Starts to look like something else, organ and tissue development
Muscle cells
cells that are designed for a specific type of tissue or structure are called determined or committed cells
myoblasts (muscle regulatory genes)
capable of making new myoblasts
don’t contain contractile proteins
differentiate
stop dividing
align
membrane fuse to form an immature muscle fiber (myotube)
myotube (more=bigger muscle)
Scaffolding for the formation of muscle fibers
What will myoblasts do to the myotubes
myoblasts will align themselves along the primary myotubes
What do myotubes and myoblasts do together
fuse together to form secondary tube
What happens after formation of secondary tube
intervention occurs
splinter away (receives a nerve)
forms myofibers
Myogenesis
occurs during the firs 2/3 of prenatal development
What matures quicker and slower?
bone and muscle - quicker
fat - slower
Determinant growth
grow to a given size (mammals)
Indeterminate growth
no predetermined size, will grow to available nutrients and environment, can create muscle fibers
Post natal growth
Phase 1-4 and myogenesis
Phase I
15-20% total growth
slow growth of all tissue
organs, bone, muscle
Phase II
75% of total growth
organ and bone growth complete
muscle hitting maximal growth
fat accumulates slowly
Phase III
80-90% of growth complete and of muscle deposited
rapid accumulation of fat
Phase IV
90-95% of additional growth is fat
5-10% of gain is muscle
Myogensis
Muscle coming to be
Hypertrophy
Hyperplasia
Hypertrophy
Increase in cell size (post natal)
Hyperplasia
Increase in cell # (prenatal)
Muscle growth
increase in muscle fiber
radial
longitudinal
radial muscle growth
fibers split to form new myofibers
induced hypertrophy
longitudinal muscle growth
stretch induced hypertrophy
bone growth
add sarcomeres
growth occurs at the end of the muscle
Protein turnover
process of building protein
replacing it with newly synthesized protein
protein accretion
more synthesis than degradation
atrophy
more degradation than synthesis
protein degradation
proteolysis breaking down proteins into peptides and amino acids
lysosomal system
sarcoplasmic proteins
25-30%
calpain system
post mortem tenderness
majority of protein degradation
ubiquitin-proteosome proticolytic pathway
binds to protein, targets the protein for degradation
Satellite cells
differentiate and enter the cell
create more DNA units
more protein synthesis
hypertrophy
factors that affect growth
genetics, nutrition, hormones, growth promotants
Genetics
double muscled, increases in fibers and myotubes, mutation of myostatin gene
Nutrition
Poor nutrition can affect muscle size
Sex hormones
testosterone, increase bone growth, increase protein synthesis
estrogen
facilitates fat deposition, stimulates muscle growth, very anabolic in ruminants
Growth hormone or somatropin
production of insulin, increase protein synthesis and decrease protein degradation, increases lipolysis
Insulin
increases storage of glucose and glycogen, fatty acids, amino acids
Leptin
decrease food intake, increase energy expenditure, decrease fat mass
Growth promotants
increase muscle cell size, beef and swine implants
