AP 1 Lec 10 Muscles

Anatomy & Physiology I
Lecture 10: The
Muscular System
Prof. Magidah Alaudi,
M.Sc.
[e-mail]

The Structural and Functional
Organization of Muscles
• About 600 human skeletal muscles
• Constitute about half of our body weight
• Three kinds of muscle tissue
– Skeletal, cardiac, smooth

• Specialized for one major purpose
– Converting the chemical energy in ATP into the mechanical energy of motion; Contraction and Movement

• Myology—the study of the muscular system

The Functions of Muscles
• Movement
– Locomotion
– movement of body parts and body contents:
•
•
•
•
•
•

breathing circulation feeding and digestion defecation urination childbirth – Role in communication: speech, writing, nonverbal communications

• Stability
– Maintain posture by preventing unwanted movements
– Antigravity muscles: resist pull of gravity and prevent us from falling or slumping over – Stabilize joints

The Functions of Muscles
• Control openings and passageways
– Sphincters: internal muscular rings that control the movement of food, bile, blood, and other materials within the body • Heat production by skeletal muscles
– As much as 85% of our body heat

• Glycemic control
– Regulation of blood glucose concentrations within its normal range Skeletal Muscle Tissue
• Large body muscles responsible for movement • Long and thin
• Usually called muscle fibers • Do not divide

• Multinucleated cells
• Striated VOLUNTARY muscle • New fibers are produced by stem cells (myosatellite cells) Cardiac Muscle Tissue
• Called cardiocytes
• Form branching networks connected at intercalated discs
– Contain GAP junctions

• Striated INVOLUNTARY muscle
• Regulated by pacemaker cells

Smooth Muscle Tissue
•

Found in walls of hollow, contracting organs –

•
•

blood vessels; urinary bladder; respiratory, digestive, and reproductive tracts

Non-striated INVOLUNTARY muscle
Can divide and regenerate

Classification of Muscle Cells
– Striated (muscle cells with a banded appearance)
–