Biology Chapter 6: Skeletal System Review

Questions and Answers

Which is a function of the skeletal system? (Select all that apply)

Support (correct)

Storage (correct)

Providing levers for muscle activity (correct)

Hematopoietic site (correct)

A bone with approximately the same width, length, and height is most likely?

a short bone

The shaft of a long bone is properly called the?

diaphysis

Sites of hematopoiesis include all but?

Medullary cavities in bones of a healthy adult Signup and view all the answers

An osteon has?

a central canal carrying blood vessels, concentric lamellae, osteocytes in lacunae, canaliculi that connect lacunae to the central canal Signup and view all the answers

The organic portion of the matrix is important in providing all but?

Hardness Signup and view all the answers

The flat bones of the skull develop from?

fibrous connective tissue Signup and view all the answers

The remodeling of bone is a function of which cells?

osteoblasts and osteoclasts Signup and view all the answers

Bone remodeling in adults is regulated and directed mainly by?

mechanical stress, and PTH Signup and view all the answers

Where within the epiphyseal plate are the dividing cartilage cells located?

between the resting zone and the hypertrophic zone Signup and view all the answers

Wolff's law is concerned with?

the shape of a bone being determined by mechanical stresses placed on it Signup and view all the answers

Formation of the bony callus in fracture repair is followed by?

bone remodeling Signup and view all the answers

The fracture type in which the bone ends are incompletely separated is?

greenstick Signup and view all the answers

The disorder in which bones are porous and thin but bone composition is normal is?

osteoporosis Signup and view all the answers

Compare bone to cartilage tissue relative to its resilience and speed of regeneration.

Cartilage consists primarily of water, is surrounded by perichondrium containing blood vessels, while bones are susceptible to fractures and regenerate at different rates. Signup and view all the answers

Describe in proper sequence the events of endochondral ossification.

A bone collar forms around the diaphysis of the hyaline cartilage model. Cartilage in the center of the diaphysis calcifies and then develops cavities. The periosteal bud invades the internal cavities and spongy bone forms. The diaphysis elongates and a medullary cavity forms. The epiphyses ossify. Signup and view all the answers

Osteocytes residing in lacunae of osteons of healthy compact bone are located quite a distance from the blood vessels in the central canals. How can this be explained?

Nutrients are relayed from one osteocyte to another via canaliculi. Signup and view all the answers

As we grow, our long bones increase in diameter, but the thickness of the compact bone of the shaft remains relatively constant. Explain this phenomenon.

The epiphyseal plate maintains a constant thickness due to balanced rates of cartilage growth and bony tissue replacement. Signup and view all the answers

Describe the process of new bone formation in an adult bone.

An osteoid seam marks areas of new matrix deposits by osteoblasts, transitioning to mineralized bone at the calcification front. Signup and view all the answers

Compare and contrast controls of bone remodeling exerted by hormones and by mechanical and gravitational forces.

PTH regulates remodeling in response to calcium levels, while mechanical stressors determine the shape and architecture of bone. Signup and view all the answers

Study Notes

Functions of the Skeletal System

Provides structural support for the body.
Serves as a hematopoietic site (blood cell formation).
Acts as a storage area for minerals and lipids.
Offers levers for muscle activity.

Bone Classification

Short bones are characterized by equal width, length, and height.

Long Bone Structure

The diaphysis is the shaft of a long bone.

Hematopoiesis Sites

Healthy adult bones do not use medullary cavities for hematopoiesis.

Osteon Composition

Contains a central canal with blood vessels.
Features concentric lamellae.
Houses osteocytes in lacunae.
Includes canaliculi connecting lacunae to the central canal.

Matrix Composition

The organic component of bone matrix does not contribute to hardness.

Skull Bone Development

Flat bones of the skull originate from fibrous connective tissue.

Bone Remodeling

Osteoblasts and osteoclasts are responsible for bone remodeling.

Bone Remodeling Regulation

Influenced primarily by mechanical stress and parathyroid hormone (PTH).

Epiphyseal Plate

Dividing cartilage cells are situated between the resting zone and the hypertrophic zone.

Wolff's Law

States that the shape of a bone is influenced by mechanical stresses placed upon it.

Fracture Repair Process

Formation of the bony callus during fracture repair is succeeded by bone remodeling.

Fracture Types

A greenstick fracture results in incompletely separated bone ends.

Osteoporosis

Characterized by porous and thin bones, yet normal composition.

Bone versus Cartilage

Cartilage is more resilient due to high water content and receives nutrients via diffusion from the perichondrium's blood vessels.
Bones are prone to fractures; larger bones take longer to heal compared to smaller ones.

Endochondral Ossification Sequence

Formation of a bone collar around the diaphysis occurs first.
Central cartilage calcifies and develops cavities next.
The periosteal bud invades these cavities, leading to the formation of spongy bone.
The diaphysis elongates, creating a medullary cavity.
Finally, ossification occurs in the epiphyses.

Osteocyte Nourishment

Osteocytes are nourished by nutrients relayed through canaliculi, connecting them to the central canal.

Long Bone Growth Dynamics

Long bones increase in diameter without increasing the compact bone thickness, as the rate of cartilage growth balances its replacement with bony tissue.

New Bone Formation

An osteoid seam indicates new matrix deposits by osteoblasts.
The calcification front is where unmineralized osteoid transitions to mineralized bone and requires about a week for proper maturation before calcification.

Bone Remodeling Controls

Parathyroid hormone (PTH) regulates remodeling by stimulating osteoclasts to release calcium into the blood, while hormonal controls dictate if and when remodeling occurs.
Mechanical stress from activities influences bone remodeling and architecture, with thickening occurring in response to demands placed on long bones.

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Test your knowledge of the skeletal system with these flashcards. Covering important functions, types of bones, and terminology, this quiz offers a comprehensive review of Chapter 6. Perfect for students preparing for exams in biology.