Three classes of muscle

• Skeletal muscle - responsible for locomotion

• Cardiac muscle - responsible for the action of the heart

• Smooth muscle - responsible for the contraction of irregular shaped organs such as the intestines.

MUSCLE TISSUE

Skeletal muscle100 µm

Multiple nuclei

Muscle fiber

Sarcomere

Cardiac muscle

Nucleus Intercalateddisk

50 µm

Smooth muscle Nucleus

Musclefibers

25 µm

NERVOUS TISSUE

NeuronsProcess

Cell body

Nucleus

50 µm

Structure and Function of Skeletal Muscle

Skeletal Muscle

• Mammal body contains over 400 skeletal muscles

– Approx. 40-50% of total body weight

Skeletal Muscle

• Functions of skeletal muscle

– Force production for locomotion and breathing

– Force production for postural support

– Heat production during cold stress

– Saleable product in livestock production

Skeletal Muscles

• Muscles generally work in pairs to produce movement

• One muscle flexes (or contracts) the other relaxes

• This process is known as antagonism

Structure of Skeletal Muscle:Connective Tissue Covering

• Epimysium– Surrounds entire muscle

• Perimysium– Surrounds bundles of muscle fibers

• Fascicles

• Endomysium– Surrounds individual muscle fibers

Structure of Skeletal Muscle:Microstructure

• Sarcolemma– Muscle cell membrane

• Myofibrils– Threadlike strands within muscle fibers– Actin (thin filament)

• Troponin• Tropomyosin

– Myosin (thick filament)

CollagenousfiberElasticfiber

Chondrocytes

Chondroitinsulfate

Loose connective tissue

Fibrous connective tissue

100

µm

100 µm

Nuclei

30 µm

Bone Blood

Centralcanal

Osteon

700 µm 55 µm

Red blood cellsWhite blood cell

Plasma

Cartilage

Adipose tissue

Fat droplets

150

µm

CONNECTIVE TISSUE

Smooth MusclesLumen ofstomach

Mucosa. The mucosa is anepithelial layer that linesthe lumen.

Submucosa. The submucosa isa matrix of connective tissuethat contains blood vesselsand nerves.

Muscularis. The muscularis consistsmainly of smooth muscle tissue.

0.2 mm

Serosa. External to the muscularis is the serosa,a thin layer of connective and epithelial tissue.

Smooth muscle