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what is growth
expanison of tissues
how is growth expressed
as per unit of measure over time
what type of growth in occurs postnatally
hypertrophic
what is hyperplasia
increase in number of cells
what is the result of hyperplasia
near exponential growth of cells
what is the main component of prenatal growth
hyperplasia
what happens during hypertrophy
cells increase in size from anabolic activity
what does hypertrophy result in
linear like whole body growth
what is a major component of postnatal growth
hypertrophy
what happens during positive growth
growth is greater than break down (anabolism>catabolism)
what is true growth
increase in structure tissues
what is another name for true growth
fat free growth
what is fat accumulation
aggregate increase of adipose tissue that rapidly increases during postnatal phase 4
what is development
continual progression toward higher tissue complexity
what is reversible growth
postitive growth followed by negative growth
what type of growth would we see during pregnancy/lactation
reversible growth
what type of growth would we see during dieting
reversible growth
what type of growth would we see during sickness/illness/injury
reversible growth
where does reversible growth occur
in adipose tissue
what is irreversible growth
tissues that can’t function with negative growth
what is negative growth
situations in which catabolism is greater than anabolism
what type of growth would we see during weaning
negative growth
what type of growth would we see during reducing plane of nutrition
negative growth
what type of growth would we see during lactation
negative growth
what type of growth would we see during breeding season
negative growth
what is lag phase critical to
determining absolute amount of growth
what causes lag phases
stressors
what is compensatory growth
rebound growth after a lag phase
what is the most ideal type of compensatory growth
recovering weight for age
what is the most typical type of compensatory growth
extending growing period
what is growth stunting a result of
nutrient restricting and critical time combination
why is growth stunting after weaning so bad
that is the critical time for tissue development
what changes first of the skeletal and body areas
the head
what changes second of the skeletal and body areas
distal limbs
what changes third of the skeletal and body areas
shoulder
what changes fourth of the skeletal and body areas
hind quarter
what changes fifth of the skeletal and body areas
rib and loin
what tissue develops first
nervous tissue
what tissue develops second
vital organs
what tissue develops third
bone
what tissue develops fourth
muscle
what tissue develops fifth
fat
what are carcass components
bone muscle fat
what are non carcass components
nervous tissue, most organs
what grows faster: muscle or bone
muscle
when does the muscle to bone ratio increase
as animals become older and heavier during primary growth phase
when does the rate of fat deposition increase
it become rapid past the inflection point on animals growth curve
what are the correlation between mature size and
daily gain, time to reach mature size weights at immature ages
what is different about larger animals growth rate
it is faster but takes longer to approach mature wight
what is chronological age
actual number of age
what is physiological. age
stage of development based on physical or chemical development such as height weight composition puberty etc
when does 15% of total growth occur
phase 1
when does nerual tissue have a faster rate of growth
phase 1
when does 75% of. total growth occur
by end of phase 2
when do organs and skeletal bone growth near completion
by the end of phase 2
when does muscle growth begin to ramp up
by the end of phase 2
when does puberty occur
by the end of phase 2
when does 80-90% of total growth occur
by the end of phase 3
when does adipose tissue production begin to ramp up
by the end of phase 3
why does stunting occur
nutritional deficiencies cause animals to break down vital cells for growth to sustain life and the break down of these cells can not be undone
what type of fat develops first
internal
what type of fat develops second
intermusclar
what type of fat develops third
subcutaneous
what type of fat develops last
intramuscular
what is physical composition
relative porportion of muscle fat and bone resulting from form change of differential growth
what makes up chemical composition
water crude fat protein ash
why is shape, apperance and composition not static
it changes from day to day
what carcass component grows at high rates
fat
what is the composition of lean muscle
70-75% water, 20-25% protein, 1-12/14% fat
what is the composition of subcut fat
10-40% water, <12% protein, 40-60/75% fat
what is chemical maturity
when a fat free body protein/ash concentration plateaus
when does protein acceleration plateau
maturity or mature body size
what is body composition influenced by
rate of gain
why to old cows have a lower dressing percentage
metabolic changes, expanded GI tract, adipose and skeletal muscle may be depleted
what is k is Huxleys unequal growth equation
growth ratio or growth coefficient
what does k>1 mean
tissue is growing faster than whole, but later developing
what does k=1 mean
growing at same rate as whole
what does k<1 mean
growing slower than whole, but earlier developing
what is a totipotent stem cell
it can develop into any type of cell including placenta and germ cell layer
what is a pluripotent stem cell
embryonic can develop into most cells
what is a multipotent stem cells
can development into secialized cells; exist in embryonic and adult phases
what part of the germ embryonic layers is the area of muscle development
the mesoderm
when does the process of cellular differentiation occur
when multipotent stem cells give rise to muscle precursor cells
what are somite patterning
dorsal portion of somite differentates into dermomytome
what do somites eventually become
skeleton, muscles
what happens with out pax 3
there is no limb development
what do multipotent stem cells differentiate into
MPC’s in the somite via transcription factors
what does the MPC’s expression of Pax3/Pax 7 lead to
proliferation or differentiation
what plays a role in attracting MPC’s to the limb bud
hepatocyte growth factor and C-Met receptor
what happens after the MPC migrates to the limb bud
Pax 3 expression decreases and myogenic regulatory factors expression increase
What are the MRFs needed for functional muscle
MyoD, MyF5, Mrf4, myogenin
what does the expression of MyoD and MyF5 play a key role in
conversion of MPCs to committed myoblasts
what do myoD and myf5 aid in
myoblasts being able to be synthesize mysoin and actin
what does the expression of myogenin do
fusing and formation of myotubes
what are myogenin and mrf4 necessary for
to cause cascade of event/protein synthesis for fusion and development myotube
what can a defect in myogenin cause
myoblasts being present but no final development of skeletal muscle
what does myogenin expression allow
myoblasts to form into primary and secondary myotubes
after myogenin expression what is a myotube
mutlinucleated, can mature into a muscle fiber, sythesize additional myofibrillar proteins into myofibril assembley, no divison occur
what is double muscling
when there is a struggle to regulate myoblasts resulting in more individual muscle cells
what signals somite patterning
the notocord through broad signalling pathways
