Ki's Cell 220 Lecture 8

What are the three types of muscle tissue?

skeletal, cardiac, smooth

Where is skeletal Muscle tissue found?

attached to bones

Where is cardiac muscle tissue found?

Heart(myocardium)

Where is Smooth Muscle Tissue found?

walls of hollow organs

What are the properties of Muscle Tissue?

electrical excitability, contractility, extensibility, elasticity

Electrical Excitability

the ability to respond to a stimulus and convert it into an action potential

Contractility

ability to shorten forcibly when stimulated

Elasticity

The ability of a material to bounce back after being disturbed

Extensibility

the ability to be stretched or extended

What are the characteristics of Cardiac Muscle?

"Y" shaped or branched fibers

Uninucleate or binucleate

Intercalated discs

Striated

Auto-rythmatic

involuntary

What are intercalated discs?

junctions between cells that anchor cardiac cells

What are the characteristics of Smooth Muscle?

Fusiform shape, uninucleate, no striations, fatigue resistant, involuntary

What is a fusiform shape?

wide at middle and tapered at ends

What are the characteristics of Skeletal Muscle?

Large cylindrical shape, Multinucleate(Fusion of Myoblasts), innervated at neuromuscualr junctions, striated, voluntary, vascular

What are the functions of Skeletal Muscle?

Movement, Maintenance of posture, Temperature regulation, Storage and movement of materials, Support abdominal organs, Joint stabilization

What is the Endomysium?

a thin layer of connective tissue that surrounds each muscle fiber

What is the Perimysium?

The connective tissue that surrounds fascicles.

What is the Epimysium?

The thin connective tissue that surrounds entire muscle

What is deep fascia?

dense irregular connective tissue around muscle

What is a muscle fiber?

a single muscle cell

What is a facicle?

bundle of muscle fibers

What creates the Muscle-tendon connection?

Collagen Fibers of Endomysium, Perimysium, and Epimysium are continue with tendons.

What do tendons do?

Tendons connect muscles to bone or skin

What is aponeurosis?

flat tendon

What is the structure of a muscle cell/fiber?

Nucleus, Mitochondrion, Sacrolemma, Myofibril composed of Sacromere.

What is Sacrolemma?

plasma membrane of a muscle cell

What is a Sacromere?

it is one unit of repeating structural and function unit of skeletal muscle

What is the sarcoplasmic reticulum?

muscle cell's smooth endoplasmic reticulum, used to store calcium ions that lines the outside of myofibrils.

What is actin filament?

thin filament of sacromere

What is the z disc?

It is protein that holds the thin filament in place creating a border between sacromere.

What is myosin filament?

thick filament of sacromere

How are thick filaments composed?

thick string of myosin molecules with heads that have both Actin and ATP binding sites

How are thin filaments composed?

Troponin, Tropomyosin, Actin with binding sites for myosin

What is Troponin?

a regulatory protein that moves tropomyosin aside & exposes myosin binding sites when Ca+ is released during muscle contraction

What is Tropomyosin?

A protein that covers the myosin binding sites

How does Sliding Filament Mechanism of Sacromere Contraction work?

The heads of the myosin filament bind to the actin filaments and pull them closer to the M line.

What is the Myelin sheath?

covers the axon of some neurons and helps speed neural impulses

What is the axon terminal?

End of axon where neurotransmitter is released.

What is the neuromuscular junction?

point of contact between a motor neuron and a skeletal muscle cell

What is a nerve impulse/action potential?

propagation of the excitable change along the cell membrane

What is a synaptic vesicle?

Vesicle that release Ach into the junction when the axon is stimulated by the action potential.

What is the synaptic cleft?

gap between nerve and muscle

What is the motor end plate?

The exact spot where the nerve and muscle meet where receptors are found.

What is the Terminal cisternae of the sacroplasmic reticulum?

Enlarged, specialized compartments of the sarcoplasmic reticulum that serve as a reservoir for calcium ions (Ca2+).

What is the T-tubule system?

Invaginations of the sarcoplasmic reticulum into the z-lines of the myofibrils delivering ions for excitation-contraction coupling.

What is a triad?

T-tubule plus 2 terminal cisternae.

What are the steps of muscle contractions?

An action potential arrives at neuromuscular junction, ACh is released, binds to receptors, and opens sodium ion channels, leading to an action potential in sarcolemma, Action potential travels along the T-tubules, Calcium is released by sarcoplasmic reticulum, thick and thin filament interaction leads to muscle contraction, muscle shortens and produces tension

What are the steps of muscle relaxation?

Calcium is resorbed; ATP is required, thick and thin filament interaction relaxes, muscle lengthens and relaxes