Human Biology in Notes
BIO 202
Chapter 6: The Skeletomuscular System
6.1 The Skeletomuscular System is Multifunctional and Dynamic
Movement is a defining characteristic of animal life
Humans move by applying tension to the bones and joints of the skeletal system
◦Tension is applied by the skeletal muscular tissue
The skeletal and muscular systems work as a cooperative unit
◦Skeletal muscles connect to bones
◦As the muscle contracts, it pulls on the bone, causing the bone to move
The Skeletomuscular System Performs
Several Key Functions
● Provides movement and locomotion
● Protects organs in the thoracic and abdominopelvic cavities
● Helps maintain homeostasis by generating internal heat
● Maintains upright posture and bipedalism
● Manipulates the environment
● In addition, the skeleton
○ ◦Produces blood cells (hematopoiesis)
○ ◦Stores and releases minerals such as calcium and phosphorus
○ ◦Calcium is required for skeletal muscle contraction – thus a vast calcium store is
readily available for skeletal muscles to tap into as they lie next to bones
The Skeleton holds the body together, while muscle provide movement
● The bones and muscles must work together to meet the internal and external demands
on the body
○ Both are made of living tissue but cannot work separate from each other
● Movement is possible because of the unique arrangement of muscle and bone
● are held together by joints, most of which permit movement between the bones
○ Pulling on one bone by muscles causes movement at the accompanying joint
● All human skeletal muscles have a similar function and structure
○ They contract, or get shorter, to produce movement
○ Muscles can relax to their original (resting) length
6.2 Bone is Strong and Light Tissue
Compact (dense) bone usually occurs at the outer edges of the bone and is composed of many
individual osteons
● Osteons are concentric rings of bone matrix laid by osteocytes
● The bone matrix consists of minerals (calcium and phosphate)
, ● The bone matrix also contains collagen fibers
○ These collagen become mineralized – turning solid and firm
○ This is in contrast to collagen fibers found in other connective tissues, which
remain flexible
Spongy bone usually forms within the deeper portions of the bone, providing inner support
● Spongy bone is porous, less organized than compact bone, and lacks osteons
● Spongy bone has trabeculae, or struts, that form in response to stress
● Trabeculae are composed of osteocytes
Osteon Structure
The center of each osteon contains a central canal (Haversian canal)
● The central canal of each osteon houses the blood and nerve supply for the bone
● Bone matrix is formed by osteoblasts and maintained by osteocytes
● Osteocytes live in lacunae (small lakes), which are small holes in bone matrix
● Canaliculi (tiny canals) extend between each lacuna, containing nutrient fluids
○ Material passes to (and between) osteocytes in lacunae as it flows through the
canaliculi
Perforating canals connect several central canals together to allow for communication
BIO 202
Chapter 6: The Skeletomuscular System
6.1 The Skeletomuscular System is Multifunctional and Dynamic
Movement is a defining characteristic of animal life
Humans move by applying tension to the bones and joints of the skeletal system
◦Tension is applied by the skeletal muscular tissue
The skeletal and muscular systems work as a cooperative unit
◦Skeletal muscles connect to bones
◦As the muscle contracts, it pulls on the bone, causing the bone to move
The Skeletomuscular System Performs
Several Key Functions
● Provides movement and locomotion
● Protects organs in the thoracic and abdominopelvic cavities
● Helps maintain homeostasis by generating internal heat
● Maintains upright posture and bipedalism
● Manipulates the environment
● In addition, the skeleton
○ ◦Produces blood cells (hematopoiesis)
○ ◦Stores and releases minerals such as calcium and phosphorus
○ ◦Calcium is required for skeletal muscle contraction – thus a vast calcium store is
readily available for skeletal muscles to tap into as they lie next to bones
The Skeleton holds the body together, while muscle provide movement
● The bones and muscles must work together to meet the internal and external demands
on the body
○ Both are made of living tissue but cannot work separate from each other
● Movement is possible because of the unique arrangement of muscle and bone
● are held together by joints, most of which permit movement between the bones
○ Pulling on one bone by muscles causes movement at the accompanying joint
● All human skeletal muscles have a similar function and structure
○ They contract, or get shorter, to produce movement
○ Muscles can relax to their original (resting) length
6.2 Bone is Strong and Light Tissue
Compact (dense) bone usually occurs at the outer edges of the bone and is composed of many
individual osteons
● Osteons are concentric rings of bone matrix laid by osteocytes
● The bone matrix consists of minerals (calcium and phosphate)
, ● The bone matrix also contains collagen fibers
○ These collagen become mineralized – turning solid and firm
○ This is in contrast to collagen fibers found in other connective tissues, which
remain flexible
Spongy bone usually forms within the deeper portions of the bone, providing inner support
● Spongy bone is porous, less organized than compact bone, and lacks osteons
● Spongy bone has trabeculae, or struts, that form in response to stress
● Trabeculae are composed of osteocytes
Osteon Structure
The center of each osteon contains a central canal (Haversian canal)
● The central canal of each osteon houses the blood and nerve supply for the bone
● Bone matrix is formed by osteoblasts and maintained by osteocytes
● Osteocytes live in lacunae (small lakes), which are small holes in bone matrix
● Canaliculi (tiny canals) extend between each lacuna, containing nutrient fluids
○ Material passes to (and between) osteocytes in lacunae as it flows through the
canaliculi
Perforating canals connect several central canals together to allow for communication
