Chapter 10: Cellular Respiration, Types of Muscle Fiber Flashcards
Events at Neuromuscular Junction NMJ (7)
- nerve impulses arrive at nerve ending, releasing ACh
- ach travels across synapse (diffusion) reaches muscle plasma mem. (sarcolemma)
- inc. in sodium ion permeability
- sodium ions travel down concentration gradient into muscle fiber, cause membrane to depolarize (-55 mv)
- action potential generated. (55mv=spread over sarcolemma surface)
- muscle fiber contract
- actylcholinesterase activity degrades ACh in synapse
resting membrane=?
must reach __ for contraction
- -70 mV
- -55 mV
sources for ATP production in muscle
- creatine phosphate
- anearobic cellular respiration
- aerobic cellular respipration
creatine phosphate
what does it store?
how is it obtained/synthesized?
most energy in muscle tissue is stored in the phosphate bond of creatine phosphate
- unique to muscle fibers
- obtained from food
- excess ATP released from relaxed muscles
- synthesis in liver + kidneys
ADP (A-P-P) + C-P —–>
ATP (A-P-P-P) + C + energy
anaerobic cellular respiration
where does it occur?
what type of energy release?
how much activity does it allow?
begins in cytoplasm and completes in mitochondria
- cytoplasm: 1 molecule of glucose converted into 2 molecules of pyurvic acid and 2 molecules of pyurvic acid + 2 molecules ATP (aka glycolysis, no CO2, exergonic)
- enough energy for 30-40 sec of activity
what is glucose oxidation?
what does it require?
series of chemical steps (mechanical steps)
each step requires different enzyme
for every glucose oxidized to CO2 and water, there is enough energy to produce _____
36 molecules of ATP
most of the ATP produced in a cell is by ______ (type)
mitochondria (endergonic)
how do cells obtain energy to produce ATP?
oxidizing fat + glucosse
glucose + oxygen = ?
CO2 + water + energy (exergonic)
what are the 2 seperate pathways in mitchondria?
krebb process + electron transport chain
end result of aerobic cellular respiration
____ used _____ produced
how much energy released?
pyurvic acid—> CO2
- oxygen used and water produced
- large amnt of energy released
2 molecules of pyurvic acid produced enough energy is released to make ___?
34 molecules of ATP
aerobic cellular respiration
___ produced in the _____
ATP production in mitochondria involving the complete oxidation of glucose, acids, or amino acids
where do muscle tissue recieve their oxygen supply from?
hemoglobin + myoglobin
aerobic respiration provides ____ % of ATP needed for muscular endurance more than ____ minutes
90, 30
muscle fatigue
more pyurvic acid is being produced than the mitochondria are capable of oxidizing
- each pyurvic acid is turned into lactic acid as it accumulates
- toxic effect
- large scale fatigue
oxygen debt
with prolonged strenuous activitY, ATP production occurs without oxygen
- excess ATP decrease the accumulation of lactic acid by converting it back into pyurvic acid
what is the size of oxygen debt?
the amnt of CO2 the mitochondria would have used to make the saem amnt of ATP
what does less ATP require?
mitochondrial use so production of ATP continues at high rate
- extra ATP used to decrease lactic acid in blood
- helps form phosphate stored in muscles
- when ATP gone so is oxygen debt
the tension a muscle can generate depends on?
of fibers that are contracting in unison
motor unit
group (150) of muscle fibers which recieve stimulation through the branches of a single spinal nerve
twitch contraction
response of all the fibers in a motor unit to a single stimulus (AP)
- 3 phases
3 phases of twitch response
- latent
- contraction
- relaxation
twitch response latent phase
instant of stimulation to beginning of contraction
- SR releases calcium to allow contraction to begin
twitch response contraction phase
dependent on?
start of contraction until max contraction
- dependent on calcium ions and formation of trigger complexes
twitch response Relaxation phase
begins to taper off as calcium is transported back into t-tubules and the SR
what happens btwn max contraction and full relaxation?
no new bridges and trigger complexes are formed
- existing trigger complexes are broken down by ATP binding to myosin
what is the refractory period?
why?
how long for each type of muscle?
time during which a muscle wont respond to a second stimulus
- muscle membrane cant immediately generate 2nd AP
- skeletal: 5millisec
- caridac: 300 millisec
wave summation
if application of 2nd stimulus occurs before muscle has completely relaxed, contracted stste of muscle is prolonged
incomplete (unfused) tetanus
what doe sit permit?
sustained muscle contraction is response to multiple stimuli (20/30 sec)
- permits partial relaxation btwn stimuli
complete (fused) tetanus
what does it lack?
sustained contraction in response to multiple stimuli (80/100 sec)
- lacks partial relaxation btwn stimuli
muscle tone
state of maintainied partial contraction of muscle
- small amnt of contraction is essential for maintaining posture
isotonic contractions
type of muscle tone
- tension doesnt change
- muscle shorten + lengthen to move a weight
isometric contractions
muscles dont shorten or lengthen
- no movement
- tension increases
- maintains posture
- supports objects in fixed position
how are skeletal muscle fibers classified?
red (dark) or white (light)
red (dark) muscle fibers
diameter
contraction
oxidative
function
fatigue?
blood supply?
myoglobin
mitochondria
metabolism
ATP
location
diameter: small
contraction: slow
oxidative: slow
function: posture, walking, sprinting
fatigue: not easily
blood supply: extensive
myoglobin: extensive
mitochondria: many
metabolism: aerobic
ATP: hydrolyzed slowly
location: middle of muscle
white (light) muscle fibers
diameter
contraction
oxidative
function
fatigue?
blood supply?
myoglobin
mitochondria
metabolism
ATP
location
diameter: large
contraction: fast
oxidative: fast
function: short suration activity (weight lifting)
fatigue: easily
blood supply: less than dark
myoglobin: les than dark
mitochondria: less than dark
metabolism: anaerobic glycolysis
ATP: hydrolyzed faster
location: periphery of muscle
most skeletal muscle contain mixture of ___ fiber types, with ___ proportions dependent on the action of the muscle
both, varying
cardiac muscle is only foudn in the walls of the ____
heart chamber (myocardium)
cardiac muscle description
- striated involuntary
- fibers are short, branched, contain 1 centrally located nucleus
- connect to adjacent fibers by intercalcated discs
cardiac muscle contractions last _____ than skeletal muscle contractions due to calcium ions entering through the intercalcated discs
10 times longer
Cardiac fibers contract __________?
independently of any nerve supply
where is smooth muscle found
how are they arranged?
walls of hollow viscera + small blood vessels
- fibers arranged in a network
smooth muscle anatomy
- involuntary +nonstriated
- fibers are fusiform shaped
- central nucleus
- sarcoplasm contains thick (myosin) + thin (actin) + intermediate filaments which arent organized into sarcomeres
- thin + intermediate filaments attached to dense bodies
smooth muscle physiology
duration of contraction and relaxation
duration of contraction and relaxation of smooth muscle is longer than in skeletal muscle due to slower movement of calcium ions
largest smooth muscle cells
gravid uterus
contraction of smooth muscle
- sliding of thick/thin filaments generate tension on intermediate filaments
- thin/intermediate filaments attach to dense bodies of the sarcolemma and corkscrew as the fibers contract slowly
- more intense contractions
smooth muscle tone
state of continued partial contraction allowed for by the prolonged presence of calcium ions
neuromuscular disease
problems involving somatic motor neurons, neuromuscular junctions, muscle fibers
myopathy
what is myopathy a symptom of?
disfunction of muscle fibers causing muscle weakness
- signifies a disease or disorder of the skeletal muscle tissue itself
myasthenia gravis
autoimmune disorder characterized by great muscular weakness
- caused by antibodies directed against ACh receptors at the neuromuscular junction
- more ACh receptors are affected as the disease progresses
- muscles become increasingly weaker
muscular dystrophies
inherited muscle destroying diseases that are characterized by degeneration of individual muscle fibers
- leads to progressive atrophy of the skeletal muscle
- most common: duchenne musc dys.
