Visualizing Human Bio Ch 6

Movement

A defining characteristic of animal life.

Human movement

Humans move by applying tension to the bones and joints of the skeletal system.

Tension application

Tension is applied by the muscular system; the skeletal and muscular systems work as a unit.

Muscle and bone arrangement

Movement is possible because of the unique arrangement of muscle and bone.

Skeletal muscle function

All human skeletal muscles have a similar function and structure (they contract, or get shorter, to produce movement).

Muscle relaxation

Muscles can relax to their original (resting) length or even elongate beyond that point.

Skeleto-muscular system functions

Works together to perform several key functions: provide movement and locomotion, manipulate the environment, protect organs in the thoracic and abdominopelvic cavities, help maintain homeostasis by generating internal heat, maintain upright posture and bipedalism.

Skeleton functions

The skeleton produces blood cells and stores and releases minerals such as calcium and phosphorus (used in muscular contraction).

Bone and muscle

Both bone and muscle are living tissue.

Movement production

Separately neither can produce movement.

Muscular tissue contraction

Muscular tissue contracts (gets shorter).

Bone pulling mechanism

When the muscle shortens, it pulls on the bone. Bones are held together by joints, most of which permit movement between the bones.

Joint movement

Pulling on one bone causes movement at the accompanying joint.

Bone formation

Bones are a form of connective tissue produced by immature bone cells called osteoblasts.

Ossification types

Ossification (bone formation) can be endochondral (formed within cartilage) or intramembranous (formed within membranes); most bones are endochondral.

Bone growth process

Growth occurs at the outer surface of the bone; cells within the membrane that covers the bone, the periosteum, differentiate into osteoblasts and begin to add matrix to the exterior.

Osteoblasts maturation

Accumulating matrix entraps these osteoblasts, which mature into osteocytes, creating new bone tissue around the exterior of the bone.

Intramembranous ossification

Intramembranous ossification forms the flat bones of the skull, clavicle, and mandible.

Dermal bones

Bones are laid down within embryonic connective tissue; they form deep in the dermis of the skin and thus are often called dermal bones.

Compact bone

Compact (dense) bone material usually occurs at the edges of the bone and is composed of many individual osteons.

Central canal of osteon

The central canal of the osteon houses the blood and nerve supply for the bone tissue.

Spongy bone

Spongy: less organized than compact bone (lacks osteons).

Trabeculae

Struts that form in spongy bones in response to stress.

Epiphyses

The ends of the bones that include the epiphyseal plate.

Epiphyseal plate

An area of cartilage where long bones continue to grow during childhood and adolescence.

Epiphyseal line

The remnant of the epiphyseal plate that forms when bones cease growing.

Hyaline cartilage

A layer found wherever two bones meet, preventing bone from grinding against bone at a joint.

Bone marrow

The substance housed in the central canal of the long bone.

Bone remodeling

The process where bones change shape throughout life, despite ceasing to grow in length at maturity.

Osteoclasts

Large cells that break down the bony matrix and release calcium and other minerals into the bloodstream.

Osteoblasts

Cells that build the mineral structure of bones by pulling calcium and minerals from the bloodstream.

Osteoid

An organic matrix secreted by osteoclasts that is converted to bone.

Calcium in bones

Calcium is removed and added in response to blood calcium levels and stress on the bones.

Physiological processes

Processes such as nerve impulse transmission and muscle contraction that require calcium stored in bones.

Blood calcium regulation

When blood calcium levels drop, osteoclasts release stored calcium; when levels rise, osteoblasts create new matrix.

Bone repair

The process that takes about three months to complete.

Closed reduction

When alignment of a fracture is possible without disturbing the skin.

Open reduction

The skin must be cut, and often metal screws, plates, or pins are used to fix the bones in place.

Complete immobilization

May not be ideal for healing bones; limited movement, stress, or partial weight-bearing activities can help the bones grow.

The skeleton

Divided into the axial skeleton and the appendicular skeleton.

Axial skeleton

The central axis of the body, comprised of 8 cranial bones, 14 facial bones, the hyoid bone, ribs, and vertebrae.

Appendicular skeleton

The appendages (arms, legs, hands, and feet) and girdles holding them to the central axis.

Cranial bones

Surround and protect the brain.

Parietal bones

Paired cranial bones that protect the upper sides of the head.

Temporal bones

Paired cranial bones that protect the middle sides of the head and support the ears.

Frontal bone

A single cranial bone at the forehead that protects the frontal lobe of the brain.

Occipital bone

The entire back of the skull, a single bone.

Facial bones

Protect the entrances to the respiratory and digestive systems, and the sensory organs.

Maxillae

Make up the front of the mouth.

Mandible

The only bone of the skull attached by a movable joint, articulates with the temporal bone at the temporomandibular joint (TMJ).

Vertebrae

Bones that allow upright posture and protect vital organs of the thoracic cavity.

Adult vertebral column

Contains 24 vertebrae, one sacrum, and three to five coccyx bones (tailbone).

Sacrum

Five fused vertebrae that form a solid base for the pelvic girdle.

Typical vertebra

Composed of three parts: the vertebral body, the vertebral arch, and the vertebral articular processes.

Vertebral column regions

Divided into the cervical region, the thoracic region, and the lumbar region.

Lumbar region

The thickest and strongest region of the vertebral column.

Intervertebral disc

A pad of fibrocartilage between each vertebra.

Disc

Serves as a shock absorber, preventing vertebrae from rubbing each other and crushing under the body's weight and allowing for limited motion between vertebrae.

True ribs

Seven pairs of ribs that attach directly to the sternum or make a direct connection with the costal cartilage, which is directly associated with the sternum.

False ribs

Five pairs of ribs that either attach to the costal cartilage (ribs 8, 9, and 10) or have free lateral ends (floating ribs 11 and 12).

Sternum

Also known as the breastbone, it protects the anterior of the chest.

Pectoral girdle

Consists of the clavicle and scapula, connecting to strong back muscles and allowing for greater range of motion in the shoulder joint.

Humerus

The longest and strongest bone in the upper appendicular skeleton.

Ulna

The bone on the pinky finger side of the forearm.

Radius

The bone on the thumb side of the forearm.

Pelvic girdle

Composed of the hip bones and lower vertebrae, denser, stronger, and less flexible than the appendicular girdle.

Hip bone

Emerges from three bones that fuse in early puberty.

Femur

Articulates at the junction of the three bones that make up the hip bone.

Acetabulum

The curved recess that serves as a socket for the head of the femur.

Pelvis

Technically made of two hip bones, the sacrum, and the coccyx.

Feminine pelvic girdles

Wider for giving birth, typically less than 90 degrees.

Joints

Link the skeletal system together; they exist whenever two bones meet and are classified by function or structure.

Muscular tissue

Contractile tissue that includes skeletal muscle, cardiac muscle, and smooth muscle.

Skeletal muscle

A contractile tissue composed of protein filaments arranged to move the skeletal system.

Origin

The end of a skeletal muscle that remains stationary when the muscle shortens.

Insertion

The end of a skeletal muscle that moves during contraction.

Myofibrils

Inside skeletal muscle cells, they contain nested, elongated structures that include microfilaments composed of actin and myosin.

Sarcomeres

Contractile units in skeletal muscle tissue that are stacked end to end in the myofibrils.