Muscle material for Lab & midterm 2

What are the 3 specific types of muscle tissue?

Skeletal muscle, cardiac muscle, and smooth muscle

What is skeletal muscle?

• (multicell nuclei) per cell

• Striated, voluntary

• attached to bone fascia & other muscle

• appear long &cylindrical in shape

• Fxn: body movement, helps posture, makes heat

What is cardiac muscle?

• (single nucleus) per cell

• Striated, involuntary

• Found in the heart

• Fxn: to pump blood throughout the body, maintaining circulation.

What is smooth muscle?

• (single nucleus) per cell, spindle shape

• Non-striated, involuntary

• Found in walls of hollow organs( stomach, intestines, blood vessels, skin)

• Fxn: regulates flow of substances, maintains internal pressure

Whats a muscle?

an organ, consist of skeletal muscle tissue & CT; muscle has belly & tendons at each end

What is a Fasicle?

• A bundle of muscle fibers surrounded by connective tissue, contributing to the overall structure of a muscle

• visible to unaided eye

What is a muscle fiber?

• A single cell of skeletal muscle, capable of contraction

• containing multiple nuclei and organized into fascicles.

What is a myofibril?

• Threadlike structures (organelles) in muscle cells

• Visible in light microscope , run parallel to cell axis

• Striated apprearance

What is the hierarchy arrangement of muscles?

Muscle > Fascicle > Muscle fiber > Myofibril> Myofilament > Muscle proteins

What is Sarcolemma?

• Plasma mbn

• The thin membrane that surrounds a muscle cell, playing a key role in transmitting electrical impulses and maintaining the cell's integrity

What is Sacroplasm?

• Cytoplasm of a muscle cell, containing various organelles, myoglobin, and nutrients essential for muscle function

What is Sarcoplasmic Reticulum?

• (modified) endoplasmic reticulum, stores calcium

What are Myofilaments?

• composed of muscle proteins: filaments slide past eachotherduring contraction

• Proteins are actin( thin filaments, light), Myosin (thick filaments, dark)

• Titin - anchors to thick filaments of Z discs

What is sarcomere?

• functional unit of muscle fiber, short segment of myofilament

• Smallest functional unit of the muscle fiber

What does the Sarcomere organization include?

• Z discs, A band(dark), I band(light), M lines(middle)

How are a bands formed?

Array of thick filaments , region of thick and thin filament overlap

What is the Sliding Filament theory of contraction?

• explains how muscles contract

• Myosin heads attach to actin, forming cross-bridges

• Myosin pulls actin toward the center of the sarcomere, shortening the muscle

• ATP (from mitochondria) is needed to detach and reset myosin heads

• Result: muscle shortens and produces force

What is the function of Muscle tissue?

• Motion- relies on integrated function of bones, joints& muscles

• Movement- of substances within body( Heart, vessels, GI, urine, sperm, ova

• Maint of posture- Stabilizes body posture

• Heat Production- Working muscles convert 75% E to heat, only 25% to motion

• Support soft tissues- abdominal wall & pelvic floor

• Guard entrances/ exits- mouth, bladder, anus

Tendon of orgin:

Attaches to least moveable bone, most proximal bone(can be more than 1)

Tendon of insertion:

Attaches to most moveable, most distal bone(only 1)

Endomysium:

Areolar CT, surrounds each muscle fiber, contains capillaries

Neuromuscular Junction:

• site where neuron interfaces with Sarcolemma of muscle fiber

• can be seen with light microscope

• Consist of Axon terminal, synaptic cleft, motor end plate

• is the synapse between a motor neuron and a muscle fiber. It enables the transmission of impulses that stimulate muscle contraction

Motor end plate=

Hold receptors for neurotransmitters

Light =

I Bad, contains only parts of thin filaments, made of actin

Dark =

A Band, contains all of thick filaments, made of myosin and ends of thin filaments

Perimysium=

Dense regular CT surrounds bundles of 10/100 fibers= fasicles ( loaded with blood supply)

Fascia=

sheet or broad band of fibrous CT deep to skin or around muscles or other organs

Superficial fascia=

-subq layer, areolar CT w/ adipose (under skin)

fxn: insulate fat storage, protection, pathway for AVLN to enter & exit muscles

Deep fascia=

Dense irregular CT, lines of body wall holds muscles together separates them into functional groups

M line is made of

• protein that holds thick filaments is found in the middle of H zone

Myoepithelial cells

in some exocrine glands, facilitate secretion

Myofibroblasts=

• In CT, participate in wound contraction

Identify this image

Skeletal muscle tissue

Identify this image

Identify this image

Cardiac muscle

Rotator Cuff (SITS)

• Supraspinatus

• Infraspinatus

• Teres minor

• Subscapularis

Quadriceps Femoris

• Rectus femoris

• Vastus lateralis

• Vastus medialis

• Vastus intermedius

Hamstring Muscles

• Biceps femoris

• Semimembranosus

• Semitendinosus

All of the following are true of the movement capabilities of joints except

The strength of the joint is determined by the strength of the muscles that attach to it and its joint capsule

Which of the following is not a fxn of synovial fluid

Increase osmotic pressure within the joint

A joint in which the articular surfaces can slide in any direction?

Multiaxial

A twisting motion of the foot that turns the sole inward is:

Inversion

The ligaments that limit the anterior and posterior movement of the femur and maintain the alignment of the femoral and tibial condyles are the …

Cruciate ligaments

Each of the following changes in skeletal muscles is a consequence of aging except

A. muscle fibers become smaller in diameter

B. Muscles become less elastic

C. Muscle fibers increase their reserves of glycogen

D. The number of myosatellite cells decreases

C. Muscle fibers increase their reserves of glycogen

The fxn of neuromuscular synapse is ..

To facilitate chemical communication between a neuron and a muscle fiber

The direct energy supply produced by the skeletal muscles in order to enable them to contract is

ATP

Another name for the muscle that is the prime mover is

Agonist

The bundle of collagen fibers at the end of a skeleton muscle that attaches the muscle to bone is called a(n)

A. Fascicle

B. Myofibril

C. Motor Unit

D. None of the above

None of the above

Which of the following is not a muscle of the rotator cuff?

A. Supraspinatus

B. Subclavius

C. Subscapularis

D. Teres Minor

Subclavius

Which of the following muscles is a flexor of the elbow?