Muscle Tissue

z line, i band, a band

1 2 3

sliding, shortening

4. Muscle contraction a. Contraction occurs through a __________movement of the thick and thin filaments over each other. b. Head groups of myosin form temporary linkages between the thick and thin filaments. After binding to the actin molecules the myosin head groups generate movement and pull the thick filaments over the thin filaments, thus _______________the length of the sarcomere. Energy for this process is generated by hydrolysis of ATP by the myosin head groups, which have ATP-ase activity.

Myosin, actin, ATP

b. Within sarcomeres thick and thin myofilaments overlap. 1) _________ heads project from the thick filaments to thin filaments. The myosin heads bind both _______(forming transient bridges between the thick and thin filaments) and ________

nuclei, cardiac muscle cells

green arrows = __________ blue circles = ___________

triad

specialized structure of skeletal muscle that aids in depolarization of the sarcolemma (caused by action potential) causeing Ca2+ release from SER leading to muscle contraction.. It consists of a central tubule called the transverse, or T-, tubule that represents an invagination of the sarcolemma. The central tubule is surrounded on either side by an expanded portion of the sarcoplasmic reticulum called the terminal cisternae. In humans, this is located at the AI junction of the sarcomere

regenerate

1. Cardiac muscle does not have satellite cells and does not _______________ 2. Damaged cardiac muscle is replaced by a fibrous scar tissue

myosin, actin, myosin, actin, sarcomeres

A-band - is the darker band. It consists of ________ , with some overlapping _______. H-band - is the lighter region in the middle of the A-band. It is an area where only ________ is present. I-band - is the lighter band. It consists of ________filaments. Z-line - is the dark line seen in the middle of the I-band. It represents the anchoring point of the actin filaments of two adjacent __________.

Purkinje

Cardiac Innervation 1. Innervated by autonomic nervous system (i.e. involuntary) 2. System of highly modified cardiac muscle cells forms a pacemaker regions of the heart and ramified throughout the organ as the ______________ system, thus coordinating contractions of the myocardium as a whole in each cardiac cycle.

ANF

Atrial cardiac muscle cells are smaller and with less T tubules than the cells of ventricles. a. They release the peptide hormone, ________________ that acts on target cells in the kidney to affect Na+ excretion and water balance.

shorter, intercalated discs

CARDIAC MUSCLE Structure 1. The cardiac muscle cells (fibers) are cylindrical and __________ than skeletal muscle fibers 2. The cells have a single, centrally located nucleus. 3. Cardiac muscle fibers split into a small number of branches that connect with similar branches from adjacent fibers. This results in a formation of a three dimensional network of cell. Between the adjacent cardiac muscle cells are specialized intercellular junctions called ___________________. They bind cardiac muscle cells together and serve to anchor myofibrils

Mitochondria

Cardiac muscle _____________are more numerous (at least 40% of cytoplasmic volume) than in skeletal muscle (2% of the cell volume).

myofibrils, myosin, actin

Each muscle fiber contains a parallel array of cytoplasmic filaments called ___________. formed by arrangements of thick ________ filaments and thin _________ filaments.

Multinucleated

Internal organization of the skeletal muscle fiber 1. Long, cylindrical or spindle-shaped muscle fibers. a. _____________ with peripherally located nuclei. b. Embryonal progenitor cells, myoblasts aggregate and fuse to produce syncytial, multinucleated myotubes. Some myoblasts do not fuse, retain the ability for mitosis and become future satellite cells. Satellite cells are skeletal muscle stem cells and they can enter mitosis after muscle damage.

hyperplasia, hypertrophy

Regeneration 1. Due to the presence of satellite cells in the endomysium, skeletal muscle has a limited capacity for regeneration after injury. a. The increase in number muscle cells - _________________ 2. Typically, an increase in the skeletal muscle mass results from the enlargement of individual muscle fibers - ____________

hollow, low

SMOOTH MUSCLE found in the walls of _________ organs (e.g. intestines, blood vessels, trachea) Often forms sheets or layers of varied thickness Specialized for continuous contractions of relatively _______force, producing diffuse movements through contraction of the whole muscle mass, rather than contraction of individual motor units. SER is not well developed and lacks T tubules Thin and thick filaments are not organized into sarcomeres, thus the cells are not striated

A

Sarcomere - is the smallest repetitive subunit of the contractile apparatus in skeletal muscle. With the light microscope, it can be seen to consist of alternating light and dark bands. Runs from Z-line to Z-line ________-band - is the darker band. It consists of myosin, with some overlapping actin.

sarcoplasmic reticulum, Ca2+

Sarcoplasmic reticulum and transverse tubule system a. In the sarcoplasm (cytoplasm of the muscle fiber) between parallel myofibrils are mitochondria and cisternae of the ________________(smooth ER of the muscle fiber) Changes in sarcoplasmic ______ concentration are essential for muscle contraction.

1, oxidative phosphorylation

Skeletal muscle fiber types Type ___ (aerobic, slow, oxidative) a. Small size fibers b. Slow contractions for long time periods, resistant to fatigue (e.g. true back muscles) c. Major source of ATP is _____________________ d. Numerous mitochondria e. High density of surrounding blood capillaries f. High levels of myoglobin, oxygen binding protein (red fibers) g. Low glycogen content, many mitochondria

2a, oxidative phosphorylation

Skeletal muscle fiber types Type __________ (fast, intermediate oxidative-glycolytic) fibers a. Medium size fibers b. Fast contractions, less resistant to fatigue than type I (e.g. major leg muscles) c. Major source of ATP is _______________ d. Numerous mitochondria e. High density of surrounding blood capillaries f. High levels of myoglobin (red fibers) g. Intermediate glycogen content

Voluntary, Neuromuscular junction, acetylcholine

Skeletal muscle innervation ____________ innervation by the peripheral nervous system _____________________ between unmyelinated axonal terminal and individual muscle fiber (motor end plate) • Neurotransmitter - _______________

a-actinin, dense bodies, desmin

Smooth muscle Bundles of thick and thin filaments crisscross obliquely through the cell. b. Thin actin filaments attach to ________________________ located in __________________ (functionally similar to Z discs) that are located throughout the sarcoplasm and near the sarcolemma 5. Abundant intermediate filaments, mostly ___________, are present. Like actin they also attach to the above

striation, Single, Involuntary

Smooth muscle Lack of ____________ • Spindle-shaped cells • __________ nucleus • ____________ innervation

very capable

Smooth muscle is ____________ (very capable/not capable) of regeneration

skeletal

There is a mix of muscle types in _________ muscles Differentiation into muscle types is partly controlled by its innervation, and fibers of a single motor unit are of the same type.

intercalated discs, functional syncytium

Transverse regions of _______________ (perpendicular to the long axis of the cell) have many desmosomes and fasciae adherentes. d. The longitudinally oriented portions of each disc have many gap junctions. This allows for a quick spread of ions between cells - _______________

2b, anaerobic glycolysis

Type ___________ (fast, white glycolytic) (i.e eyeballs) a. Large size fibers b. Fast contractions, susceptible to fatigue; capable of fast, precise, and fine movements (e.g. extraocular muscles) c. Major source of ATP is ________________ d. Relatively sparse mitochondria e. Lower density of surrounding blood capillaries f. Low levels of myoglobin (white fibers) g. High glycogen content

H

____-band - is the lighter region in the middle of the A-band. It is an area where only myosin is present.

I

_______ -band - is the lighter band. It consists of actin filaments

Z line

_________ - is the dark line seen in the middle of the I-band. It represents the anchoring point of the actin filaments of two adjacent sarcomeres.

cardiac, intercalated disks

_________ muscle, arrows are pointing to _________

Muscle spindles, intrafusal fibers

__________ - stretch detectors, part of muscle proprioceptor system. a. Approximately 2 mm long, consists of a few thin muscle fibers called ________________ encapsulated by modified perimysium. Several sensory nerve fibers penetrate each muscle spindle and wrap around individual ones b. Changes in length of the surrounding (extrafusal) muscle fibers caused by body movements are detected by the muscle spindles and the sensory nerves relay this information to the spinal cord.

cardiac, capillaries

____________ muscle, arrows point to __________

cardiac, intercalated disks

______________ muscle, arrows are pointing to ___________

Myasthenia gravis

_______________ o Autoimmune disease in which autoantibodies to neurotransmitter ACh receptors in muscle cells block the binding of ACh

skeletal

________________ muscle

Motor unit

________________: a group of muscles innervated by a single spinal nerve a. In precisely controlled muscles (e.g. extraocular muscles or hand muscles is small. b. In muscles with less precision (e.g. erector spinae), can have more than 100 muscle fibers

skeletal, perimysium, endomysium

__________________ muscle Attached to bone by tendons or aponeuroses and surrounded by CT layer called the epimysium (deep fascia) The muscle belly can be subdivided into smaller units called fascicles; each fascicle is surrounded by CT layer called the ____________(2) Each fascicle is formed by a bundle of muscle cells a. Each muscle cell is called a muscle fiber, vary in diameter and length b. Each muscle fiber is surrounded by an external lamina and a thin layer of CT called the ______________(1)

skeletal

__________________ muscle Fibers may be very long The cytoplasm of skeletal muscle cells stains pink with routine H&E, and displays distinct striations or stripes which reflect the presence of repeating contractile units called sarcomeres. Cells have multiple nuclei which are located at the periphery of the cell.

motor end plates

_____________________

Smooth

______________muscle -long, spindle-shaped cells with thick middles and tapered ends.The cytoplasm of the cell stains pink with H&E, and is homogenous without striations. There is a single centrally located nucleus that is usually described as vermiform or wormlike. Because the cells are so long, the nucleus is frequently not seen in cross-section.

Neuro

__________pathies - lost innervation to the muscle Occurs in diseases caused by degeneration of motor neurons (e.g. amyotrophic lateral sclerosis (ALS), Guillain-Barré syndrome)

Myo

_________pathies o Innervation to the muscle remains intact o Include hereditary muscular dystrophies o Can be a result of aging, malnutrition, and immobilization