CH6 Bone Tissue and the Skeletal System

Endochondral ossification follows five steps.

(a) Mesenchymal cells differentiate into chondrocytes. (b) The cartilage model of the future bony skeleton and the perichondrium form. (c) Capillaries penetrate cartilage. Perichondrium transforms into periosteum. Periosteal collar develops. Primary ossification center develops. (d) Cartilage and chondrocytes continue to grow at ends of the bone. (e) Secondary ossification centers develop. (f) Cartilage remains at epiphyseal (growth) plate and at joint surface as articular cartilage.

Where two bones meet Bone Markings Examples

Articulations Knee joint

Long Bone: Features Function(s) Examples

Cylinder-like shape, longer than it is wide Leverage Femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges

Inhibits osteoclast activity and stimulates calcium uptake by bones

Calcitonin

Stimulates absorption of calcium and phosphate from digestive tract

Calcitriol

form the hydroxyapatite crystals that give bone its hardness

Calcium

Passage in bone Bone Markings Examples

Canal Auditory canal

Types of Fractures: A fracture in which the skin remains intact

Closed (or simple)

Types of Fractures: Several breaks result in many small pieces between two large segments

Comminuted

Irregular Bone: Features Function(s) Examples

Complex shape Protect internal organs Vertebrae, facial bones

Rounded surface Bone Markings Examples

Condyle Occipital condyles

Ridge Bone Markings Examples

Crest Iliac crest

Short Bone: Features Function(s) Examples

Cube-like shape, approximately equal in length, width, and thickness Provide stability, support, while allowing for some motion Carpals, tarsals

Flat surface Bone Markings Examples

Facet Vertebrae

Slit through bone Bone Markings Examples

Fissure Auricular fissure

Structural component of bone

Fluoride

Hole through bone Bone Markings Examples

Foramen Foramen magnum in the occipital bone

Elongated basin Bone Markings Examples

Fossa Mandibular fossa

Small pit Bone Markings Examples

Fovea Fovea capitis on the head of the femur

Types of Fractures: A partial fracture in which only one side of the bone is broken

Greenstick

Prominent rounded surface Bone Markings Examples

Head Head of femur

Holes and depressions Bone Markings Examples

Holes Foramen (holes through which blood vessels can pass through)

a condition characterized by abnormally low levels of calcium, can have an adverse effect on a number of different body systems including circulation, muscles, nerves, and bone.

Hypocalcemia

Types of Fractures: One fragment is driven into the other, usually as a result of compression

Impacted

Slight, elongated ridge Bone Markings Examples

Line Temporal lines of the parietal bones

Structural component of bone

Magnesium

Opening into canal Bone Markings Examples

Meatus External auditory meatus

Types of Fractures: Occurs at an angle that is not 90 degrees

Oblique

Reduces inflammation that may interfere with osteoblast function

Omega-3 fatty acids

Types of Fractures: A fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection

Open (or compound)

Stimulates osteoclast proliferation and resorption of bone by osteoclasts; promotes reabsorption of calcium by kidney tubules; indirectly increases calcium absorption by small intestine

Parathyroid hormone

Prominence feature Bone Markings Examples

Process Transverse process of vertebra

Raised markings Bone Markings Examples

Projections Spinous process of the vertebrae

Protruding Bone Markings Examples

Protuberance Chin

____ fills the spaces in the spongy bone.

Red marrow

is where hematopoiesis—the production of blood cells—takes place. Red blood cells, white blood cells, and platelets are all produced

Red marrow

resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed. & Injury, exercise, and other activities

Remodeling

These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a joint.

Sesamoid bone

Promote osteoblastic activity and production of bone matrix; responsible for adolescent growth spurt; promote conversion of epiphyseal plate to epiphyseal line

Sex hormones

Air-filled space in bone Bone Markings Examples

Sinus Nasal sinus

Sesamoid Bone: Features Function(s) Examples

Small and round; embedded in tendons Protect tendons from compressive forces Patellae

Sharp process Bone Markings Examples

Spine Ischial spine

Types of Fractures: Bone segments are pulled apart as a result of a twisting motion

Spiral

Groove Bone Markings Examples

Sulcus Sigmoid sulcus of the temporal bones

Flat Bone: Features Function(s) Examples

Thin and curved Points of attachment for muscles; protectors of internal organs Sternum, ribs, scapulae, cranial bones

Stimulates bone growth and promotes synthesis of bone matrix

Thyroxine

Types of Fractures: Occurs straight across the long axis of the bone

Transverse

Small, rounded process Bone Markings Examples

Tubercle Tubercle of humerus

Rough surface Bone Markings Examples

Tuberosity Deltoid tuberosity

Needed for calcium absorption

Vitamin D

Supports bone mineralization; may have synergistic effect with vitamin D

Vitamin K

contains adipose tissue; the triglycerides stored in the adipocytes of the tissue can serve as a source of energy

Yellow marrow

a thin layer of cartilage that reduces friction and acts as a shock absorber.

articular cartilage

is where two bone surfaces come together

articulation

The nerves sense pain, and it appears the nerves also play roles in regulating ___ (2), hence their concentrations in metabolically active sites of the bone.

blood supplies and in bone growth

The periosteum contains ____(3) that nourish compact bone. ____ (2) also attach to bones at the periosteum.

blood vessels, nerves, and lymphatic vessels Tendons and ligaments

The process in which matrix is resorbed on one surface of a bone and deposited on another is known as ____.

bone modeling

channels within the bone matrix.

canaliculi

The only short bones in the human skeleton are in the ____ and the ____.

carpals of the wrists tarsals of the ankles

The walls of the diaphysis are composed of dense and hard ____.

compact bone

The two layers of ____ (2) work together to protect the internal organs

compact bone and the interior spongy bone

is the tubular shaft that runs between the proximal and distal ends of the bone.

diaphysis

Flat bones, like those of the cranium, consist of a layer of ____ (spongy bone), lined on either side by a layer of compact bone

diploë

In ____ ossification, bone develops by replacing hyaline cartilage.

endochondral

The medullary cavity has a delicate membranous lining called the ____ , where bone growth, repair, and remodeling occur.

endosteum

The periosteum covers the entire outer surface except where the ____ meet other bones to form joints. In this region, the epiphyses are covered with ____

epiphyses articular cartilage

The wider section at each end of the bone is called the ____, which is filled with ____.

epiphysis spongy bone

Bone also serves as a site for ____ and ____.

fat storage blood cell production

Increases length of long bones, enhances mineralization, and improves bone density

growth hormone

is an opening or groove in the bone that allows blood vessels and nerves to enter the bone

hole

The ____ crystals give bones their hardness and strength, while the collagen fibers give them ____ so that they are not brittle.

hydroxyapatite flexibility

a condition characterized by abnormally high levels of calcium, the nervous system is underactive, which results in lethargy, sluggish reflexes, constipation and loss of appetite, confusion, and in severe cases, coma.

hypercalcemia

The flat bones of the face, most of the cranial bones, and the clavicles (collarbones) are formed via ____

intramembranous ossification.

Each osteocyte is located in a space called a ____ and is surrounded by bone tissue.

lacuna

found at the borders of adjacent lamellae.

lacunae

Each osteon is composed of concentric rings of calcified matrix called ____

lamellae

The hollow region in the diaphysis is called the _____, which is filled with yellow marrow.

medullary cavity

Each epiphysis meets the diaphysis at the____

metaphysis

the narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline (transparent) cartilage in a growing bone.

metaphysis

The arteries enter through the ____, small openings in the diaphysis

nutrient foramen

When the bone stops growing in early adulthood (approximately 18-21 years), the cartilage is replaced by ____ tissue and the epiphyseal plate becomes an ____.

osseous epiphyseal line

early osteoblasts appear in a cluster called an ____.

ossification center

is the bone cell responsible for forming new bone and is found in the growing portions of bone, including the periosteum and endosteum.

osteoblast

Four types of cells are found within bone tissue:

osteoblasts, osteocytes, osteogenic cells, and osteoclasts

The cell responsible for bone resorption, or breakdown

osteoclast

the primary cell of mature bone and the most common type of bone cell

osteocyte

These osteogenic cells are undifferentiated with high mitotic activity and they are the only bone cells that divide.

osteogenic cell.

uncalcified matrix, which calcifies (hardens) within a few days as mineral salts are deposited on it, thereby entrapping the osteoblasts within.

osteoid

The microscopic structural unit of compact bone

osteon

also known as Volkmann's canals

perforating canal

The outer surface of the bone is covered with a fibrous membrane called the ____

periosteum

By the second or third month of fetal life, bone cell development and ossification ramps up and creates the ____, a region deep in the periosteal collar where ossification begins

primary ossification center

is an area of a bone that projects above the surface of the bone

projection

is the next layer toward the diaphysis and contains stacks of slightly larger chondrocytes.

proliferative zone

The longitudinal growth of bone is a result of cellular division in the ___ and the maturation of cells in the ____.

proliferative zone zone of maturation and hypertrophy

is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix.

reserve zone

After birth, this same sequence of events (matrix mineralization, death of chondrocytes, invasion of blood vessels from the periosteum, and seeding with osteogenic cells that become osteoblasts) occurs in the epiphyseal regions, and each of these centers of activity is referred to as a ____.

secondary ossification center

the lacunae and osteocytes are found in a lattice-like network of matrix spikes called ____.

trabeculae

Intramembranous ossification begins in ____ during fetal development and continues on into adolescence.

utero

the zone closest to the diaphysis, are dead because the matrix around them has calcified.

zone of calcified matrix

are older and larger than those in the proliferative zone.

zone of maturation and hypertrophy