APSC 4514 Exam 2

myogenesis

The formation of muscle through the muscle origins (dermatome and myotome) begining in uteroand continuing into postnatal development. It involves the differentiation of mesodermal cells into myoblasts, which then fuse to form muscle fibers

dermomyotome

where all muscle cells start from

myotome

The part of the somite that gives rise to the muscles of the trunk and limbs, derived from mesodermal cells.

Myogenenic regulatory factors

master genes that regulate muscle development and differentiation

early mrfs

myoD

My15

late mrfs

Myogenin

MRF4

indeterminant growth

a type of growth that continues throughout the organism's life, allowing for unlimited size. ex. fish

birth

every cell you have is determined at _____

double muscling

characterized by the presence of excess muscle fibers, resulting in increased muscle mass. It is often seen in certain breeds of cattle. d

swine

double muscling is not selected in _____ because they are already so muscular that the trait would provide no added benefit.

myostatin

double muscling results from a mutation of _____

tough

double muscling causes tough or tender meat? think about the connective tissue

negatively

myostatin _____ controls muscle mass because the mutation renders myostatin non-functional and muscle mass increases as a result. Differention is delayed

callipygo gene

causes muscle hypertrophy in sheep

mice

muscle hypertrophy in ____ is caused by follistatin gene- encoding an inhabitor of myostatin

follistatin

a protein that acts as a potent antagonist of myostatin (normally limits muscle growth)

Myogenin

determined MRF

determination/commitment

upregulation of MRF genes mean that the cell has no choice but to become a muscle cell when turned on

differentiation

skillset is to contract. It expresses the gene to contract

maturation

last step of myogenesis

myofibril

what is the unique organelle of the muscle cell

myoblast

what is a determined part of myogenesis

muscle fiber precursor cell

myoblasts, primary and secondary myotubles, muscle fibers

identify morphological aspects of myogenesis slide

true

primary and secondary myotubules differ depending on when they were formed

post mitotic

stop replication after formation

fiber size factors

gender

species

genetics

age

diet

adaptation

muscle used more often or at a higher workload will increase in size and strength

types of exercise

type 1

type 2A

type 2x

type 2B

endurance

_____ exercise increases the proportion of type 2A fibers

type 2B

increased proportion through weightlifting and sprinting exercises

concentric

shortens to cause movement

eccentric

lengthens to resist, control, or slow down movement

isometric (static)

generates muscle tension, but no change in the length of the muscle

isotonic (dynamic)

involves applying force with movement

muscle contraction occurs while muscle changes length

radial

_____ growth occurs in response to exercise

de novo synthesis of myofibrils

splitting of myofibrils

longitudinal

_____ growth occurs in response to stretch

addition of new sarcomeres

lengthening of the sarcomeres

interphase and mitotic phase

phases of cell cycle

anabolic steroids

testosterone and estrogen

both increase muscle mass

testosterone

differentiation of satellite cells

protein sysnthesis

cross-sectional area of both type 1 and type 2a fibers

estrogen

fiber size

overall muscle weight

muscle regeneration

growth hormone

insulin like growth factor-1 that increases msucle mass through:

differentiation of satellite cells

protein synthesis

protein degradation

adipose tissue

a heterogenous tissue with diverse functions that affetcs whole-body energy balance. type of connective tissue

Gap 1 phase

all cells enter here and this phase can be from 3-12 hours long depending on the circumstances

S-phase

period of time the cell dedicates to replication or synthesis

Gap 2 phase

ranges from about 2.4 to 2.5 hours in length for mnay muscle cell types and represents the stage when the intracellular architecture remodels itself to accommodate physical division of the cell mass in mitosis (M-phase)

Mitosis

the shortest lasting phase of the cell cycle (about an hour)

growth factors

often times these are small proteins that bind to cell surface receptors and signal to the nuclei the status of the environmental milieu

false

all growth factors are proteins. they do not include steroids

mitogens

factors that stimulate replication of cells; steroids are capable of binding receptors in the cellular cytoplasms and migrating to the nucleus to effect a response

true

growth factors can also inhibit replication

true

if non-muscle cells are genetically modified to express MRFs the cells will become myogenic

helix-loop-helix

specialized structure located in the nucleus of a muscle cell

don’t

myoblasts _____ contract because they do not contain contractile proteins or have not attained the level of specialization where contraction is possible

quiescent

not all myoblasts become differentiated. instead, they can remain _____ for long periods of time even though they have stopped replicating