Muscle Tissue

Muscle Tissue Characteristics

• Smooth muscle tissue is characterized by longitudinal cuts and is involuntary.
• Skeletal muscle tissue has striations and is voluntary.

Sarcomere Structure

• Z-disks anchor the actin filaments of two sarcomeres in a skeletal muscle.
• The A-band of a sarcomere contains only myosin (thick filaments).
• The I-band of a sarcomere contains only thin filaments (actin).
• The M-line of a sarcomere contains myosin and actin filaments.

Cardiac Muscle Characteristics

• Cardiac muscle tissue is found in the heart and is involuntary.
• Cardiac muscle tissue has striations, is branched, and has intercalated discs.

Muscle Function

• The main function of muscle tissue is to contract and produce movement.

Golgi Tendon Organs and Muscle Spindles

• The main function of Golgi tendon organs is to detect changes in muscle length and tension.
• Muscle spindles and Golgi tendon organs provide proprioception (sense of position and movement).

Cardiac Muscle Characteristics

• Intercalated discs provide connective forces between cardiac muscle cells.
• Actin and myosin are arranged in a hexagonal lattice in cardiac muscle.
• The conformational change of tropomyosin in cardiac muscle is triggered by calcium ions.
• T-tubules in cardiac muscle trigger calcium release from the sarcoplasmic reticulum.
• Titin connects to the z-line and attaches to the myosin filament.
• The trigger for all muscle contraction is the binding of calcium ions to troponin-tropomyosin complex.
• The source of internal (intracellular) Ca++ in muscle cells is the sarcoplasmic reticulum.

Neuromuscular Junction

• Botulinum toxin disrupts the neuromuscular junction.

Muscle Types

• Cardiac muscle is responsible for rhythmic contraction/relaxation due to slow leakage of Ca++.
• The sinoatrial (SA) node controls the rhythmic contraction of cardiac muscle.
• Smooth muscle is influenced by autonomic (sympathetic/parasympathetic) control and hormonal control.
• Cardiac muscle contains Purkinje fibers in the ventricles of the heart.
• Smooth muscle is specialized for slow, steady contraction.
• Smooth muscle is found in blood vessels, respiratory tract, digestive tract, uterus, bladder, and more.
• Smooth muscle uses calmodulin and myosin light-chain kinase (MLCK) instead of troponin and tropomyosin.
• Smooth muscle is innervated by post-ganglionic autonomic nerves.

Test your knowledge on muscle tissue and sensory characteristics in this quiz. Learn about Golgi tendon organs, nerve endings, skeletal, cardiac, and smooth muscles, as well as their classifications, vocabulary, structural organization, and contraction mechanisms. Discover the disruptions and sensory characteristics associated with muscle tissue.