Chapter 10 Muscle Tissue

Contractile proteins contain?

Myosin and actin

Epimysium

Encircles whole muscle

Creatine phosphate is synthesized by?

Excess ATP

smooth muscle tissue is found in?

Found in walls of hollow internal structures (blood vessels, airways), most organs in the abdominopelvic cavity, and in skin attached to hair follicles

Satellite cells in muscle

Retain capacity to fuse and regenerate functional muscle fibers

Synapse occurs between which two parts of the muscle tissue?

Somatic motor neuron and a skeletal muscle fiber

maximum tension when at an optimal zone of overlap between?

thick and thin filaments

the zone of overlap of contains?

thick and thin filaments lie side by side

regulatory proteins contain?

tropomyosin and troponin

What are the four steps of the contraction cycle?

-ATP hydrolysis -attachment of myosin to actin to form cross bridges -power stroke, and detachment of myosin from actin

What is the process of excitation-contraction coupling?

-Action potential along sarcomere and into T tubules -Ca ions released from SR -Calcium combines with troponin -Conformational change -Troponin-tropomyosin complex moves -Myosin-binding sites free -Myosin heads bind to actin -Contraction cycle begins

What happens during the detachment of myosin from actin?

-Myosin head is still attached to actin -ADP binds to the myosin head -myosin head detaches from actin

The process of the power stroke is?

-Pocket on myosin head where the ADP is bound opens -rotates myosin head toward the centre of sarcomere -releases ADP -Myosin head detaches from the actin

What are the parts of the NMJ?

-Synaptic end bulb -Synaptic vesicles -Neurotransmitters (ACh) -Motor end plate -ACh receptors -Synaptic Cleft

What occurs during the attachment of myosin to actin to form cross bridges?

1. Myosin head is then energized 2. Myosin binding sites on actin 3. Releases previously hydrolyzed phosphate group

What is the process of the contraction cycle of a muscle?

1. SR releases Ca ions 2. Ca Ions bind to the troponin 3. Troponin-tropomyosin then uncover binding sites 4. Contraction cycle begins

thin filaments of myofibrils are about how big compared to thick?

1/2 the diameter of thick filaments

Creatine phosphate vs. ATP is?

3-6x more plentiful

Muscle constitues what percentage of total body weight?

40-50%

Sarcoplasmic Reticulum (SR)

A fluid-filled system of membranous sacs that encircles each myofibril

What is released across the synaptic cleft?

ACh

What occurs in ATP hydrolysis?

ATP is converted to ADP+Phosphate group and reaction energizes myosin head

Contractility

Ability of muscle tissue to contract forcefully when stimulated by an action potential

Elasticity

Ability of muscle tissue to return to its original length and shape after contraction or extension

Extensibility

Ability of muscle to stretch without being damaged, allows muscle to contract forcefully even if it is already stretched

Electrical excitability

Ability to respond to certain stimuli by producing electrical signals, such as action potentials (impulse)

Which two types of cellular respiration occur during muscle metabolism?

Anaerobic and aerobic respiration

Perimysium

Connective tissue surrounding a fascicle

What type of molecules are unique to muscle fibers?

Energy-rich molecules

Sarcolemma

Fiber's plasma membrane

What is the life process of making myoblasts?

Hundreds of myoblasts, fusion, mature skeletal muscle fiber

What occurs during excitation-contraction coupling?

Increased Ca Ions concentration in cytosol starts muscle contraction; a decrease stops it

deep layer of connective muscle tissue

Lines the body wall and limbs and holds muscles with similar functions together Allows free movement of muscles, carries nerve and blood and lymph vessels, and fills spaces between muscles

In muscle metabolism, production of ATP occurs in?

Muscle fibers

Connective tissues surround?

Muscle fibers and whole muscles

creatine phosphate is present in?

Muscle metabolism

muscle action potential arise at the?

Neuromuscular Junction(NMJ)

smooth muscle features

Non-striated, involuntary

Myoglobin

Oxygen-binding protein only in muscle fibers

What are the main functions of muscle tissue?

Producing body movements, stabilizing body positions, regulating organ volume, moving substances within the body, producing heat

Triad

a T tubule with 2 terminal cisterns on either side

Fascia

a sheet or band of fibrous connective tissue that is deep to the skin and surrounds muscles and other organs of the body

Ach is terminated by?

acetylcholinesterase enzyme

Motion results from

alternating contraction (shortening) and relaxation of muscles

H zone of sarcomere

are in the centre of A-band, no thin filaments

M line of sarcomere

are in the centre of H zone

sarcomeres are the?

basic functional units of myofibril

During muscle contraction, myosin heads attach to and "walk" along thin filaments at?

both ends of the sarcomere, pulling thin filaments towards the M line

Aponeuroses

broad, flat layer tendon

myofibril consists of thin and flick filaments arranged in?

compartments called sarcomeres

What are the three types of muscle proteins?

contractile, regulatory, structural

tendon

cord of dense regular connective tissue that attaches a muscle to the periosteum of bone

the sarcoplasm is the (blank) of a muscle cell

cytoplasm

Terminal cisterns

dilated end sacs of the SR; against the T tubule

What are the properties of muscle tissue?

electrical excitability, contractility, extensibility, elasticity

Nerve impulses at synaptic end bulbs triggers?

exocytosis of synaptic vesicles

A-band of sarcomere

extends the entire length of thick filaments

T (Transverse) tubules open to the outside of the fibers and filled with?

extracellular fluid

Myofibrils are composed of

filaments, sarcomeres, and proteins

Bonding of ACh to its receptors in sarcolemma opens?

gated ion channels(Na+)

Glycogen is split into?

glucose, then used for ATP synthesis

Skeletal muscle is a separated organ composed of?

hundreds of cell fibers

myofibrils extends the entire?

length of the muscle

NMJ usually located at the?

midpoint of the muscle fiber

the release of acetylcholine stops when?

motor neuron action potentials cease

Although bones provide leverage and form the framework of the body, they cannot

move body parts themselves

blood vessels and nerves penetrate into?

muscle

During embryonic development, each skeletal muscle fiber arises from the fusion of hundreds of small mesodermal cells called

myoblasts

T (Transverse) tubules

nvagination of the sarcolemma that tunnel from the surface toward the center of each muscle fiber

sarcomeres have two thin filaments for every?

one thick filament

Z-discs of sarcomeres

pass through the centre of each I-band

structural proteins keep thick and thin filaments in?

proper alignment

The power stroke is triggered by the?

release of phosphate group

I-bands of sarcomere

rest of thin filaments, no thick filaments

Calcium ion active transport pumps

return calcium ions to the sarcoplasmic reticulum

Endomysium

separates individual muscle fibers from one another

thin filaments slide inward, z discs come together, shortening the sarcomere, then?

shortens the muscle fibers and shortens the entire muscle

What are the three types of muscle tissue?

skeletal, cardiac, smooth

Sarcoplasmic Reticulum (SR) is similar to?

smooth ER in non-muscle cells

cardiac muscle features

striated and involuntary

Skeletal muscle tissue features

striated and voluntary

Forcefulness of contraction depends on?

the length of the sarcomere before contraction begins

inflow of Na+ makes ICF more (+) charged, which changes?

the membrane potential and triggers a muscle action potential

structural proteins contain?

titin, myomesin, nebulin, dystrophin

Skeletal muscle tissue functions

to move bones of the skeleton

sarcomeres are separated by?

z discs

Myofibrils are contractile elements of?

Skeletal muscle

Acetylcholine (ACh)

Acetyl+choline

Potential propagates along the?

Sarcolemma and through the T tubule system

calcium release channels

Sarcoplasmic Reticulum close

Superficial (or SQ layer) connective tissue

Separates muscle from skin, pathway for nerves and vessels for muscles

What is the function of the Sarcoplasmic Reticulum?

Storage of calcium ions in a relaxed muscle fiber and releases calcium from terminal cisterns to trigger muscle contraction