Muscle Tissue Flashcards
What features distinguish the 3 types of muscular tissue?
controllability, striation, lining/direction of fibers, location of nucleus, # of nuclei
general functions of muscular tissue
> produce movement
Stabilize body positions and maintain posture
generates heat through thermogenesis
stores substances using sphincters and moves substances using peristaltic contractions
Describe 4 properties of muscular tissue
> excitable = responds to a stimuli
contractible = shorten in length
extensible = extend or stretch
elastic = return to original shape
What are 3 connective tissue layers in a skeletal muscle?
epimysium, perimysium, endomysium
Describe the microscopic anatomy of a skeletal muscle fiber
individual muscle fibers are bundled into fascicles and are surrounded by 3 C.T. layers that are extensions of the fascia
plasma membrane of the muscle fiber
sarcolemma
tunnel from surface that directs toward the center of a muscle fiber
Tranverse (T tubule)
cytoplasm of a muscle fiber
sarcoplasm
sarcoplasm appears stuffed with myofibrils
contractile organelles
what surrounds the myofibril
sarcoplasmic reticulum
what are inside myofibrils
filaments
what are the compartments for filaments called
sarcomeres
thin filaments composed of what protein
actin
what protein makes up thick filaments
myosin
what part of a sarcomere:
separates one sarcomere from another; narrow; plate-shaped
Z-disc
what part of a sarcomere:
darker middle part; extends entire length of thick filaments
A-band
what part of a sarcomere:
lighter, less dense area; contains rest of thin filaments; Z disc passes through
I-band
what part of a sarcomere:
located at the center of A-band; contains thick, but NOT thin filaments
H-zone
Outline the steps involved in the sliding filament mechanism of muscle contraction
- ATP hydrolysis
- Attachment
- Power Stroke
- Detachment
_________ - Myosin hydrolyzes ATP
- myosin enters ready state
- myosin binds (If Ca2+ releses, binds troponin and tropomysin) actin
- phosphate release, power stroke
- ADP release, “rigor”
- myosin binds ATP, unbinds actin
Describe how muscle action potentials are begun at neuromuscular junction.
- Release of ACh
- Activation of ACh receptors
- Production of action potential
- Termination of ACh activity
3 ways to produce ATP
creatinine phosphate, anaerobic glycolysis, aerobic respiration
formed from ATP when muscle is relaxed, transfers a high-energy phosphate group to ADP, forming ATP during muscle contraction
creatine phosphate
breakdown of muscle glycogen into glucose and production of pyruvic acid from glucose via glycolysis; no oxygen is needed; yields 2 molecules of lactic acid and 2 molecules of ATP
anaerobic glycolysis
O2 is required; Inside the mitochondria, pyruvic acid, fatty acids and amino acids are used. When O2 is present, glycolysis, krebs cycles, and the electron transport chain occur
aerobic respiration
phases of a twitch contraction
> Latent Period
contraction period
relaxation period
refractory period
brief delay between application of the stimulus and beginning of a contraction. The muscle action potential sweeps over the sarcolemma and calcium ions are released from the sarcoplasmic reticulum [twitch]
latent period
Ca2+ binds to troponin, myosin-binding sites on actin are exposed, and cross-bridges are formed. Peak tension develops in the muscle fiber. [twitch]
contraction period
Ca2+ is actively transported back into the SR, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases [twitch]
relaxation period
period of lost excitability [twitch]
refractory period
What type of contraction?
tension developed in the muscle remains almost constant while the muscle changes its length; used for body movements and for moving objects
isotonic contraction
What type of contraction?
muscle contraction in which the muscle shortens while generating force; reduces the angle at a joint
concentric isotonic contraction
What type of contraction?
muscle tension is less than the resistance (muscle lengthens); tension exerted by myosin cross-bridges resists movement of a load and slows the lengthening process
eccentric isotonic contraction
What type of contraction?
results in NO MOVEMENT; muscle force and resistance are equal; supporting objects in fixed position and posture; no change in length for muscle; important for maintaining posture and for supporting objects in fixed position; stabilize some joints
isometric contraction
What type of skeletal muscle fiber?
small, appear dark red, least powerful; fatigue resistant; slow-twitch; generates ATP mainly by aerobic respiration
slow oxidative (SO)
What type of skeletal muscle fiber?
intermediate in size, appear dark red, moderately resistant to fatigue; aerobic respiration and anaerobic glycolysis
fast oxidative-glycolytic fibers (FOG)
What type of skeletal muscle fiber?
large, white and powerful; generate ATP mainly by glycolysis; fatigue quickly
fast glycolytic (FG) fibers
muscle-muscle connection
fascia
sheet or band of fibrous connective tissue
fascia
skeletal muscle-bone connection
tendon
connects 2 muscle bellies
aponeurosis
