Anatomy lecture - Chapter 10

Flashcards covering the properties, functions, types, and disorders of muscle tissue to aid in exam preparation.

Contractility

The ability of muscle cells to shorten, achieved through myofilaments, primarily actin and myosin.

Excitability

The capacity of muscle cells to respond to nerve signals, causing electrical impulses to travel through the plasma membrane.

Extensibility

The ability of muscle tissue to be stretched without damage; skeletal muscles can be stretched by opposing muscles.

Smooth muscle is stretched by substances within that hollow organ

▪ Food in stomach; urine in urinary bladder

Elasticity

The property of muscle tissue that allows it to return to its original shape after being stretched, recoil.

Skeletal Muscle Tissue

Muscle tissue that is striated, voluntary, and makes up about 40% of body weight.

Cardiac Muscle Tissue

Striated, involuntary muscle tissue found only in the heart.

Smooth Muscle Tissue

Non-striated, involuntary muscle tissue that constitutes the walls of hollow organs.

Sarcolemma

The plasma membrane surrounding muscle cells.

Sarcoplasm

The cytoplasm of muscle cells.

Neuromuscular Junction

The synapse or junction where the axon terminal of a motor neuron meets the muscle fiber.

T Tubules

Deep invaginations of the sarcolemma that convey action potentials into the muscle fiber.

Sliding Filament Mechanism

The process where myosin heads pull thin filaments toward the center of the sarcomere, resulting in muscle contraction.

Oxidative Fibers

Skeletal muscle fibers that produce ATP aerobically.

Glycolytic Fibers

Skeletal muscle fibers that produce ATP anaerobically by glycolysis.

Fast Glycolytic Fibers

Muscle fibers that contract rapidly, depend on anaerobic pathways, and tire quickly.

Muscular Dystrophy

A group of inherited diseases causing progressive muscle degeneration.

Sarcopenia

Age-related muscle wasting characterized by the loss of muscle mass and strength.

Functions of muscle tissue: Produce movement

– Skeletal muscle—attached to skeleton

▪ Moves body by moving the bones

– Smooth muscle—squeezes fluids and other

substances through hollow organs

Functions of muscle tissue: Open and close body passageways

– Sphincter muscles function as valves

▪ Open to allow passage of a substance

▪ Contract to close the passageway

Functions of muscle tissue: Maintain posture and stabilize joints

• Enables the body to remain sitting or standing

• Muscle tone helps stabilize many synovial joints

Functions of muscle tissue: Heat generation

• Muscle contractions produce heat

• Helps maintain normal body temperature

Connective tissue and fasicles

Sheaths of connective tissue bind a skeletal muscle and its fibers together

Epimysium

dense regular connective tissue surrounding entire muscle

Perimysium

fibrous connective tissue that surrounds each fascicle (group of muscle fibers)

Endomysium

a fine sheath of connective tissue wrapping each muscle cell

Connective tissue sheaths are continuous with

tendons

• When muscle fibers contract, pull is exerted on all

layers of connective tissue are tendon

• Sheaths provide elasticity and carry blood vessels

and nerves

Muscle attachements

• Origin—less movable attachment

• Insertion—more movable attachment

fig 10.4 fair ID- know all the ID

Nerves and blood vessels: Each skeletal muscle supplied by branches of

• One nerve

• One artery

• One or more veins

Direct attachments

CT fibers are short

Indirect attachments

CT forms a tendon or aponeurosis

myofibrils

Contractile elements within muscle fibers that consist of repeating units called sarcomeres, which contain actin and myosin filaments.

z disc (z line)

The boundary structure of a sarcomere that anchors the actin filaments and plays a crucial role in muscle contraction.

thin (actin) filaments

The protein strands in muscle fibers made primarily of actin. They interact with myosin during muscle contraction, forming cross-bridges.

thick (myosin) filaments

The protein strands in muscle fibers made primarily of myosin. They interact with actin during muscle contraction, facilitating the sliding filament mechanism. Contains ATPase enzymesthat hydrolyze ATP for energy.

A bands

Dark bands of sarcomeres that contain both actin and myosin filaments, contributing to the striated appearance of skeletal muscle.

H zone

The zone within the A band of a sarcomere that contains only myosin filaments, appearing lighter than the surrounding regions. It is where there is no overlap between actin and myosin during muscle contraction.

M line

The line in the center of the H zone of a sarcomere that serves as an anchor point for myosin filaments, stabilizing their position during muscle contraction.

I band

The lighter bands of a sarcomere that contain only actin filaments, located on either side of the A band. They appear less dense and are involved in muscle contraction.

Titin

A large protein that functions as a molecular spring, anchoring myosin filaments to the Z line in a sarcomere and contributing to the elasticity and stability of muscle fibers.

sarcoplasmic reticulum

A specialized organelle in muscle cells that stores and releases calcium ions, playing a crucial role in the regulation of muscle contraction.

terminal cisterns

enlarged areas of the sarcoplasmic reticulum that store calcium ions and are closely associated with the T-tubules, facilitating rapid calcium release for muscle contraction.

terminal boutons

The bulbous endings of nerve fibers that release neurotransmitters into the synaptic cleft, facilitating communication between neurons and muscle fibers.

synaptic cleft

The small gap between the terminal boutons of a neuron and the muscle fiber membrane where neurotransmitters are released, allowing for signal transmission.

slow oxidative fibers

slow oxidative fibers are also known as Type I muscle fibers. Type of muscle fibers that are resistant to fatigue, primarily using aerobic metabolism for energy and containing a high number of mitochondria and myoglobin.

fast  oxidative fibers

Fast oxidative fibers are also known as Type IIa muscle fibersType of muscle fibers that generate quick bursts of power and fatigue rapidly, primarily relying on anaerobic metabolism for energy. They have fewer mitochondria and myoglobin compared to slow oxidative fibers.

myofascial pain syndrome

A chronic pain disorder characterized by muscle pain and tenderness, often due to trigger points in the muscles.

fibromyalgia

A disorder characterized by widespread musculoskeletal pain, fatigue, and tenderness in localized areas, often accompanied by sleep disturbances and emotional distress.

myoblast

Embryonic precursor cells that develop into muscle fibers, playing a crucial role in muscle growth and repair.