Human Bio: Chapter 6

Name the parts of the skeletal system

bones, joints, cartilages, ligaments, tendons

What are the 2 divisions of the skeletal system?

axial and appendicular

What are the 5 functions of the skeletal system?

1. Support

2. Mineral and Triglyceride Storage

3. Blood Cell Production

4. Production

5. Movement

Matrix always contains _____, _____, ____, _____, ____.

Collagen, ground substance, organic molecules, water, and minerals

T/F: proteoglycans make up a large amount of ground substance

True

Proteoglycans attract _______.

Water

Proteoglycans help tissue _____________.

Withstand compression

Tendons are

Muscle to bone

Ligaments are

Bone to bone

Cartilage is

Pad/cushion areas around bone

Cells embedded with cartilage are called _____.

Chondrocytes

What is an osteoblast?

Formation of bone matrix; repair/remodel of bone tissue; produce collagen and proteoglycans (ossification)

What is an osteocyte?

Mature cells that maintain bone matrix

What is an osteoclast?

Cells that break down matrix; bone cells release minerals through osteolysis

Most minerals are in a form of _________.

Calcium phosphate

T/F: mineral component gives weight-bearing strength and is responsible for 3/4 of the weight of the 206 bones in an adult.

False- it's responsible for 2/3 of the weight

Osteocytes are located in spaces called ______, in the _________.

Lacunae; lamellar matrix

Canaliculi is

Small channels that run through the matrix to transport nutrients and remove waste

Compact bone is made of a repeating functional unit called_____.

Osteon

Osteon is made up of concentric circles of ________.

Lamella w/ embedded lacunae; and surrounds the central canal

What are perforating canals?

They allow for blood vessels in the central canals to linked to other vessels

Spongy bone is located @ the ______ of ______ & at the center of other bones.

Epiphysis; long bones

Spongy bone contains _____ interconnecting rods and spaces that contain ______.

Trabiculae; bone marrow

T/F: spongy bone has no osteons

True

Spongy bone is found in locations w/ ______ arriving from many different directions.

Stresses

______ bone is much lighter than ______ bone and reduces weight of skeleton and makes it easier for muscles to move.

Spongy; compact

What are the 4 general shapes of bones?

Long, short, irregular, flat

What is an example of a long bone?

humerus, femur

What is an example of a short bone?

carpals and tarsals

What is an example of a flat bone?

Sternum, cranial bones

What is an example of an irregular bone?

Vertebrae, hip bones, facial bones

Which bone shape has compact bone on the inside w/ hollow central marrow cavity?

Long bone

The epiphysis are wider portions at each end, made up of _____.

Spongy bone

What is an epiphyseal plate?

Site of growth between diaphysis & epiphysis; solidifies into epiphyseal line when full adult height is reached

What is a medullary cavity?

Center of diaphysis; holds red/yellow marrow

What is periosteum?

Membrane around bone's outer surface; contains blood vessels/nerves; tendons/ligaments attach here

What is endosperm?

Membrane that lines the medullary cavity; contains osteoblasts & osteoclasts; involved in growth & repair

Ossification is _______.

Formation of bone by osteoblasts

Intramembranous ossification is_______.

Bone formation occurs within connective tissue membranes

Endochondral ossification is________.

Bone formation that occurs inside hyaline cartilage

Both intramembranous and endochondral bone formation result in ______ and _____ bone.

Compact, spongy

Intramembranous ossification occurs primarily in the ______ when osteoblasts begin to produce bone within connective tissue, known as mesenchyme.

Skull

In intramembranous ossification, osteoblasts line up ________, & begin depositing bone matrix to form trabiculae, which radiate out from centers of the ossification centers.

On the surface

____ or more _________ exist in each flat skull bone and mature skull bones result from fusion of these centers as they enlarge.

2, ossification centers

Intramembranous ossification generally occurs during the ________ of fetal development, & forms the bones of the skull, mandible, and the clavicle.

First 2 months

Endochondral ossification is initially formed is a ________, which is bone formation in the diaphysis of a long bone.

Primary ossification center

__________ is bone formation in the epiphysis.

Secondary ossification center

What are the steps in endochondral ossification?

1. Chondroblasts build a cartilage model, then become chondrocytes

2. Cartilage model hardens (calcifies)

3. Osteoblasts invade calcified cartilage and a primary ossification center forms the diaphysis

4. Secondary ossification centers form the epiphysis

5. Original cartilage model is almost completely ossified; remaining cartilage is known as articular cartilage

During bone growth, when cartilage is broken down, the enclosed cartilage is digested away which opens up a _______.

Medullary cavity

Bone replaces _____ through the action of _____.

Cartilage, osteoblasts

Dying chondrocytes are replaced by ______.

Osteoblasts

Bones grow in width by the periosteum & the existing matrix _______.

Appositional growth

What are the requirements for bone growth?

Mineral supply, vitamin D3, hormones, & vitamins A, B, C, D, K

T/F: timing of epiphyseal closure varies from bone-bone and from person-person

True

Bones are remodeled in response to what 2 factors?

1. Free calcium levels in the blood

2. Pull of gravity & muscles on the skeleton

Bone remodeling involves:

-removal of existing bones by osteoclasts

-deposition of new bones by osteoblasts

In young adults ____ of the skeletal mass is replaced each year.

1/5

T/F: spongy bone is replaced more often than compact

True

In adults, osteocytes in lacunae continuously _____ & _____ surrounding calcium salts.

Remove, replace

Remodeling bone (esp. spongy bone) is based on:

Appropriate stress & exercise

T/F: muscle is a major storage site for calcium

False- bone is major storage site

Calcium homeostasis is maintained by _____ & ______.

Parathyroid hormone, calcitonin

Parathyroid hormone (increase or decrease) formation/activation of osteoclasts.

Increase

A closed fracture is

Simple; completely internal and only seen on x-rays

An open fracture is

Compound; project through the skin and are at most risk for infection

What are the steps in bone repair?

1. Broken bone causes bleeding and a fracture hematoma forms

2. Cells of periosteum/endosteum divide to form a callus(internal/external)

3. Cartilage model forms first, then osteoblasts enter the callus and form spongy bone; continues for 4-6 weeks after injury

4. Cancellous bone is slowly remodeled to form compact & cancellous bone

When placed under stress, tissue becomes stronger through ________ & production of collagen fibers.

Increased decomposition of mineral salts

Without mechanical stress, bone does not remodel normally because ________.

Resorption out-spaces bone formation

When there's an absence of mechanical stress, bone weakens through decreased # of ______ and demineralization (loss of bone minerals).

Collagen fibers

What is osteopenia?

Inadequate ossification that naturally occurs in aging as early as 30-40 years old

Osteoblasts _____.

Slow

Osteoclasts _____.

Remain constant

What is osteoporosis?

Loss of bone mass that impairs normal function and can lead to more fractures

T/F: osteoporosis is more severe that osteopenia

True

Osteoporosis is more common in what gender?

Females

For women, osteoporosis usually accelerates after _____ due to decline in circulating estrogen.

Menopause

Foramen is

A large hole/opening

Fossa is

depression

Process is

Projection

Condyle is

Smooth, round ended

Meatus is

Canal-like passageway

Tubercle is

Lump of bone

Axial skeleton forms the _____.

Longitudinal axis of the body

The axial skeleton contains ____ bones.

80

How many bones are in the skull?

22 (8 cranial, 14 facial)

How many bones are in the thoracic cage?

25

How many bones in the vertebral column?

26

The axial skeleton is framework for support/protection of the ____, ____, and ____.

Brain, spinal cord, organs in the ventral body cavity

The axial skeleton provides surface area for muscle attachment such as:

Move head, neck, and trunk

Respiration

Stabilize elements of the appendicular skeleton

The skull houses the ____ & ____.

Brain, sensory organs

What skull bone encloses the brain?

Cranium

The facial bones also include associated bones, _____ and _____.

6 auditory ossicles, 1 hyoid bone

Skull bones are joined together by _____-interlocking immovable joints.

Sutures

The ______ is the only bone attached by a freely moveable joint.

Mandible

The cranium is composed of __ _____ bones.

8 flat

Frontal-

Forehead

Parietal-

Superior/lateral (top sides of the head)

The parietal bone meets midline @ _____ suture.

Saggital