Bio 201- Unit 2

The structural divisions of the skeleton

Axial and appendicular skeleton

Axial skeleton

Encases body cavities to protect underlying organs

Appendicular skeleton

Suited for movement, support, and muscle attachment

Number of bones in body

206 bones

Depressions

Dent in bone, protect or attach

Facet (Depression)

Shallow surface where two bones articulate

Fossa (Depression)

Indentation into which another structure fits

Fovea (Depression)

Shallow pit

Groove (Depression)

Long indentation along which a narrow structure travels

Openings

Hole, enclose

Fissure (Openings)

Narrow slit in or between bone

Canal (Openings)

Tunnel through bone

Foramen (Openings)

Hole in bone

Projections

Protrude, attach

Condyle (Projections)

Rounded end of a bone

Crest (Projections)

Ridge

Head (Projections)

Round projection

Tubercle/Tuberosity (Projections)

Small rounded bony projection/Large tubercle

Epicondyle (Projections)

Small projection

Process (Projections)

Prominent bony projection

Spine (Projections)

Sharp process

Protuberance (Projections)

Outgrowth from a bone

Trochanter (Projections)

Large projection, only on femur

Line (Projections)

Long, narrow ridge

Cranial bones

Frontal, occipital, ethmoid, sphenoid, 2 temporal, 2 parietal

Major sutures on skull

Sagittal, coronal, squamous, lambdoid

Facial bones

2 maxillary, 2 zygomatic, 2 nasal, 2 lacrimal, 2 palatine, 2 inferior nasal conchal, mandible, vomer

Hyoid bone

Airway protection and speech

Features of vertebral column

7 cervical

12 thoracic

5 lumbar

5 fused sacral

3-5 fused coccygeal

Structure of intervertebral discs

Fibrocartilage pad found between body part of vertebrae

Function of intervertebral discs

Absorbs shock and binds vertebral column together

Components of the thoracic cage

Sternum, 12 pairs of ribs, thoracic vertebrae

Function of thoracic cage

Form protective peripheral boundary, shield the heart, great blood vessels

Compenents of the pectoral girdle

Clavicle, scapula, 30 bones of upper limb

Four regions of upper limb

Branchium, antebrachium, carpus, hand

Brachium

Humerus, only bone in arm

Antebrachium

Lateral radius and medial ulna

Hand

5 long bones, 14 phalanges

Carpus

8 short bones in 2 rows

Components of the pelvic girdle

Fused ilium, ischium, pubis (os coxae)

Four regions of the lower limb

Femoral, crural, tarsal, pedal

Femoral

Femur, only bone in thigh, and patella

Crural

Medial tibia and lateral fibula

Tarsal

7 short bones

Pedal

5 metatarsals and 14 phalanges

Functions of skeletal system

Protection, mineral storage, blood cell formation, fat storage, movement, and support

How bones are classified

Based on shape

Ex of long bones

Bones in arms and legs

Ex of short bones

Bones of wrist and ankle

Ex of flat bones

Ribs, pelvis, sternum, and most bones in skull

Ex of irregular bones

Vertebrae and certain skull bones

Ex of sesamoid bones

Patella

Structure of long bones

Periosteum, perforating fibers, diaphysis, epiphysis, marrow cavity, compact bone, spongy bone, endosteum, epiphyseal lines, and epiphyseal plates

Structure of short, flat, irregular, and sesamoid bones

Covered by periosteum with perforating fibers

Internally composed of 2 outer layers of thin compact bone and a middle layer of diploe with bone marrow

Unique structure of flat and irregular bones of skull

Contain hollow, air-filled spaces called sinuses to reduce bone weight

Diploe

Spongy bone, not in long bones

Red bone marrow

Consists of loose connective tissue, in adults only found in pelvis, proximal femur and humerus, thoracic cage, clavicle, scapulae, and some bones of skull

Yellow bone marrow

Composed of triglycerides, blood vessels, and adipocytes

Inorganic component in bone tissue ECM

Consists of minerals and makes up 65% of bones weight, predominantly made of calcium salts

Organic components in bone tissue ECM

MAkes up 35% remaining, consists of collagen, proteoglycans, glycosaminoglycans, glycoproteins, and bone-specific proteins

Main cell types in bone tissue

Osteoblasts, osteocytes, osteoclasts

Function of osteoblasts

Bone building cells that preform bone deposition

Function of osteocytes

Ability to recruit osteoblasts to build up or reinforce bone under tension

Function of osteoclasts

Responsible for bone resorption, break down organic matrix

Ossification

Process of bone formation

Another name for ossification

Osteogenesis

Intramembranous ossification

Forms many flat bones, including bones of the skull and clavicles, during fetal development

Endochondral ossification

Bone development for all bones below head except clavicles, uses bony collar ad secondary ossification centers

Long bone growth

Longitudinal growth, division of chondrocytes in epiphyseal plate, growth takes place at epiphysis on side closest to diaphysis

Appositional growth

Bones grow in width, osteoblasts lay down new bone, does not result in immediate formation

Bone resorption

The removal of minerals and collagen fibers from bone by osteoclasts

Bone deposition

Make organic matrix and faciliate formation of inorganic matrix

Physical factors that influence bone remodeling

Tension and stress, heavier loads (compression) increase tissue deposited in that bone

Hormonal factors that influence bone remodeling

Testosterone promotes bone deposition, estrogen inhibits osteoclast activity, as growth and sex hormones decline protein synthesis in bone decreases

Dietary factors that influence bone remodeling

Calcium ions, vitamin D, vitamin C, vitamin K, proteins

Calcium ions influence bone remodeling

Adequate to support bone remodeling,

Vitamin D influence bone remodeling

Adequate to promote calcium ion absorption

Vitamin C influence bone remodeling

Adequate for synthesis of collagen

Vitamin K influence bone remodeling

Adequate for synthesis of calcium ion binding glycoproteins secreted by osteoblasts

Protein influence bone remodeling

Adequate for osteoblasts to synthesize

Role of calcitonin in bone remodeling

Leads to bone deposition, pulls calcium ions out of blood to make inorganic ECM

Role of parathyroid hormone in bone remodeling

Increases osteoclast activity, breaks down inorganic ECM releasing calcium from blood crystals, inhbits calcium loss in urine

Role of vitamin D in bone remodeling

Important for absorption of calcium ion from the gut

Role of calcium ion in homeostasis

Bone stores most of calcium ions in body, used for done deposition and remolding as well as muscle contraction

Functional classification of joints

How they move

Synarthrosis, amphiarthrosis, diarthrosis

Synarthrosis

Does not allow any movement

Amphiarthrosis

Only a small amount of movement

Diarthrosis

Freely moveable, allowing a wide variety of specific movements

Structural classification of joints

How they're put together

Fibrous, cartilaginous, synovial

Fibrous joint

Fastened together by dense regular collagenous connective tissue, no joint space

Cartilaginous joints

Fastened together with cartilage, no joint space

Synovial joints

Have layer of hyaline cartilage on articulation surface of each bone, joint space is fluid filled cavity

Subclasses of fibrous joints

Suture, gomphosis, syndesmosis