Bone Structure and Function Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What type of bone is roughly cube-shaped and includes the bones of the wrist and ankle?

Flat bones

Irregular bones

Long bones

Short bones (correct)

Which type of bone cells are responsible for bone resorption?

Osteoprogenitor cells

Osteocytes

Osteoblasts

Osteoclasts (correct)

What is the structural layer of bone that provides dense and solid material?

Spongy bone

Articular bone

Compact bone (correct)

Cancellous bone

Which type of bone are vertebrae classified as?

Irregular bones Signup and view all the answers

What role do osteoblasts serve in bone health?

They rebuild bone tissue Signup and view all the answers

Which bone structure is primarily responsible for maintaining bone tissue?

Osteocytes Signup and view all the answers

What is the primary composition of bone tissue?

Connective tissue and extracellular matrix Signup and view all the answers

Which component of bone cells promotes the digestion of bone matrix?

Enzymes from osteoclasts Signup and view all the answers

What forms the embryonic skeleton before week 8?

Hyaline cartilage and fibrous membranes Signup and view all the answers

Which process describes the replacement of hyaline cartilage with bone?

Endochondral ossification Signup and view all the answers

Which of the following bones are formed through intramembranous ossification?

Frontal and parietal bones Signup and view all the answers

What are mesenchymal cells before they differentiate into osteoblasts during ossification?

Embryonic connective tissue Signup and view all the answers

What is the ossification center?

The starting point of bone formation Signup and view all the answers

What is primarily produced during the initial stages of intramembranous ossification?

Spongy bone Signup and view all the answers

What is one main requirement for osteoblasts during their activity in ossification?

A source of oxygen and nutrients Signup and view all the answers

Which type of bone development is more complex, involving the breakdown of existing cartilage?

Endochondral ossification Signup and view all the answers

What is the primary function of T-tubules in muscle fibers?

To allow rapid transmission of action potentials Signup and view all the answers

Which proteins are primarily involved in muscle contraction?

Myosin and Actin Signup and view all the answers

What role does the heavy chain of myosin play in muscle contraction?

Acts as a motor domain that binds ATP Signup and view all the answers

How are thick filaments structured in skeletal muscle?

Myosin tails cluster in the center with heads at the ends Signup and view all the answers

What type of protein is G-actin, and how does it usually exist in muscle fibers?

A globular protein that polymerizes into F-actin Signup and view all the answers

What is the significance of the myosin-binding site on G-actin?

It facilitates the formation of crossbridges Signup and view all the answers

What structural arrangement do thin filaments exhibit in a myofibril?

Two twisted polymers of F-actin Signup and view all the answers

Which accessory proteins are linked to the structure of myofibrils?

Titin and Nebulin Signup and view all the answers

What occurs to chondrocytes near the center of the cartilage model as they enlarge?

They become deprived of nutrients. Signup and view all the answers

What is formed when blood vessels grow into the perichondrium surrounding the cartilage shaft?

A periosteum that initiates bone growth. Signup and view all the answers

What does the presence of osteoclasts accomplish during endochondral ossification?

They degrade spongy bone to create a medullary cavity. Signup and view all the answers

What defines the primary ossification center in the context of endochondral ossification?

The point where bone first appears in the diaphysis. Signup and view all the answers

Around birth, most long bones have which of the following characteristics?

Cartilaginous epiphyses and a bony diaphysis. Signup and view all the answers

What triggers the differentiation of fibroblasts into osteoblasts during endochondral ossification?

The breakdown of calcified cartilage. Signup and view all the answers

During endochondral ossification, what primarily happens to the cartilage model as growth occurs?

The cartilage is transformed into spongy bone. Signup and view all the answers

What happens to the epiphyseal cartilage during endochondral ossification while the diaphysis is elongating?

It continues to grow in thickness. Signup and view all the answers

What happens to the length of the A band during muscle contraction?

It remains constant during muscle contraction. Signup and view all the answers

What initiates the power stroke in muscle contraction?

The release of calcium ions. Signup and view all the answers

What is the role of ATP in muscle contraction?

It provides energy for the sliding motion of filaments. Signup and view all the answers

What occurs to the I band and H zone during muscle contraction?

They almost disappear. Signup and view all the answers

What happens to myosin heads after completing a power stroke?

They release actin and re-cock to bind a new actin molecule. Signup and view all the answers

How does myosin act as an ATPase during muscle contraction?

By hydrolyzing ATP to ADP and Pi, releasing energy. Signup and view all the answers

What does the term 'cocked' refer to in myosin heads?

The state where potential energy is stored in the myosin head. Signup and view all the answers

What is the primary function of the sliding filament theory?

To illustrate how muscles can contract without changing their length. Signup and view all the answers

What role does troponin play in muscle contraction?

It regulates the positioning of tropomyosin. Signup and view all the answers

What must occur for tropomyosin to shift to the 'on' position?

Calcium binds to troponin C. Signup and view all the answers

What happens when calcium concentration in the cytosol decreases?

Tropomyosin returns to the 'off' position. Signup and view all the answers

What is the rigor state in muscle contraction?

Myosin is tightly bound to G-actin without any nucleotides. Signup and view all the answers

What is the effect of ATP binding on the myosin head?

It decreases the actin-binding affinity of myosin. Signup and view all the answers

During which phase does myosin bind to a new actin molecule after ATP hydrolysis?

In the cocked position. Signup and view all the answers

What is the primary trigger for the muscle contraction process to initiate?

Calcium signaling. Signup and view all the answers

What allows the contractile cycle to repeat during muscle contraction?

Uncovered myosin-binding sites on actin. Signup and view all the answers

Study Notes

Musculoskeletal System

The musculoskeletal system is composed of bones, cartilage, and ligaments
Provides support and protection for the body
Site of hematopoiesis (blood cell production)
Stores calcium and phosphorus
Allows body movement
Skeletal system is composed of dynamic living tissues: osseous tissue, cartilage, fibrous CT, blood, and nervous tissue.
Continuously rebuilds and remodels itself throughout a lifetime
Works in conjunction with other organ systems

General Osteology and Arthrology

Osteology: The study of bones
Bones: Organs of the skeletal system.
Skeletal System: Bones and associated cartilages.
Arthrology: The study of joints (fulcrum of movement)
Endoskeleton: Internal skeleton (endo- = inside)

Skeletal System

Composed of bones in the skeleton, cartilage, and other connective tissues that stabilize or connect the bones
Includes:
- bones
- cartilage
- ligaments
- Other connective tissues, which stabilize or connect the bones.

Functions of The Skeletal System

Support: Framework for the entire body, supports legs, pelvic girdle, vertebral column, mandible (teeth), and various organs/tissues
Protection: Shields against trauma. Protects brain, lungs, heart, and spinal cord
Movement: Skeletal muscles use bones as levers to move the body
Reservoir: Reservoir for minerals (99% of body's calcium, and 85% of body's phosphorous) and adipose tissue (found in the marrow of certain bones)
Hematopoiesis: Also known as blood cell formation, occurs in the marrow of certain bones.

Cartilage

Characteristics:
- Weaker than bone
- More flexible than bone
- Cells in an abundant matrix
Types: Hyaline, fibrocartilage, elastic
Functions:
- Supporting soft tissues
- Providing a gliding surface at articulations (joints)
- Providing a model for the formation of most bones

Types of Cartilage

Hyaline cartilage: Most abundant type, has a perichondrium (membrane), associated with synovial joints, most bones first modeled in hyaline cartilage.
Fibrocartilage: Has collagen fibers, intervertebral discs, pubic symphysis
Elastic cartilage: Has elastic fibers, ear, respiratory tubing

Classification of Bones by Organization

Axial skeleton: Forms the long axis of the body (skull, vertebral column, rib cage)
Appendicular skeleton: Bones of the upper and lower limbs and girdles (shoulder bones and hip bones), attaches to the axial skeleton and involved in locomotion and manipulation of the environment

Classification of Bones by Shape

Long bones: Much longer than they are wide (all limb bones except the patella), consist of a shaft plus 2 expanded ends
Short bones: Roughly cube shaped (wrist and ankle)
Flat bones: Thin, flattened, and usually a bit curved (scapulae, sternum, costae, and most skull bones)
Irregular bones: Have irregular shapes that fit none of the 3 previous classes (vertebrae, hip bones, some skull bones)

Bone Structure

Bones are organs, composed of multiple tissue types:
- Bone tissue (osseous tissue)
- Fibrous connective tissue
- Cartilage
- Vascular tissue
- Lymphatic tissue
- Adipose tissue
- Nervous tissue
Osteons (Haversian systems) are cylindrical structural units functioning as weight-bearing pillars, that are arranged parallel to one another along the long axis of compact bone

Bone Cells

Osteoprogenitor cells: Stem cells, derived from mesenchyme, produce other stem cells and osteoblasts
Osteoblasts: Synthesize and secrete collagen and other organic components, initiate calcification, found in periosteum and endosteum
Osteocytes: Mature bone cells, trapped by the matrix, no longer secrete matrix, responsible for maintaining bone tissue
Osteoclasts: Huge cells derived from fusion of monocytes, digest bone matrix, part of normal bone growth, concentrated in the endosteum

Bone Matrix

Consists of organic and inorganic components (1/3 organic, 2/3 inorganic by weight).
Organic components: Secreted by osteoblasts, composed of several materials, collagen fibers, and other organic materials provide bone resilience
Inorganic components: Consists mainly of calcium phosphate and calcium hydroxide (form compound hydroxyapatite), contain smaller amounts of magnesium, fluoride, and sodium, give bone its hardness.

Structure of Long Bone

Diaphysis: Shaft
Epiphyses: Expanded ends (proximal and distal)
Metaphysis: Region between diaphysis and epiphyses
Epiphyseal line: Remnant of epiphyseal plate
Articular cartilage: Hyaline cartilage covering epiphyses
Medullary cavity: Marrow cavity

Structure of Short, Irregular and Flat Bone

Thin plates of periosteum-covered compact bone on the outside and endosteum-covered spongy bone within.
Have no diaphysis or epiphyses since they are usually not cylindrical
Contains bone marrow between trabeculae, but no marrow cavity
In flat bones, the internal spongy bone layer is known as diploë, resembling a stiffened sandwich

Bone Marrow

General term for soft tissue
Occupies medullary cavity of long bones and among trabeculae of spongy bone
Two types:
- Red bone marrow: Blood cell-forming tissue (hematopoietic)
- Yellow bone marrow: Fatty marrow

Ossification (Osteogenesis)

Bone tissue formation.
In embryos, leads to the bony skeleton.
As children & young adults, part of bone growth and repair.
In adults, part of bone remodeling & repair.
Begins in embryo (eighth-twelfth weeks): from mesenchyme OR hyaline cartilage models.
Intramembranous ossification: Development of bone from a fibrous membrane.
Endochondral ossification; Replacement of hyaline cartilage with bone.

Bone Growth

Interstitial growth: Occurs in epiphyseal plate as chondrocytes undergo mitosis; growth in length
Appositional growth: Occurs within periosteum; growth in diameter

Bone Remodeling

Continual deposition of new bone tissue and removal (resorption) of old bone tissue
Helps maintain calcium and phosphate levels in body fluids
Occurs at periosteal and endosteal bone surfaces

Wolff's Law

Bones adapt to loads under which they're placed
- Increased loading leads to stronger bones
- Decreased loading leads to weaker bones

Axial Skeleton

Includes the skull, vertebral column, and thoracic cage

Appendicular Skeleton

Includes the bones of the upper and lower limbs, also includes the girdles (pectoral girdle and pelvic girdle)

The Skull

Cranial and facial bones form the cranium
- complete, rounded structure that surrounds and encloses the brain
- facial bones protect the entrances to the digestive/respiratory systems
- attach to facial muscles
Mandibular bone makes up the lower jaw; Forms lower jaw
Cavities of the skull: large cranial cavity, orbits, oral cavity, nasal cavity, and paranasal sinuses

Sutures of the Skull

Immovable fibrous joints that form between cranial bones
Dense regular connective tissue forms the cranial bones together
Allows cranium to grow and expand during childhood

Muscular System

Three types of muscle tissue:
- skeletal
- cardiac
- smooth
Skeletal: Attached to bones, enable body movement
Cardiac: Only in the heart, moves blood through the circulatory system
Smooth: Primary muscle of internal organs and tubes

Skeletal Muscle

Make up the bulk of muscle in the body
Typically attached to bones by tendons of collagen
Origin: End near the trunk or more stationary bone
Insertion: End near the more distal or mobile attachment
- Flexor: Muscle causing bones to move closer
- Extensor: Muscle causing bones to move farther apart

Antagonistic pairs

Most joints contain antagonistic muscle pairs (flexors and extensors)
- Contraction pulling a bone in one direction, but also requires an opposing muscle preventing opposite motion.
Muscles pulling in opposite directions
E.g., biceps and triceps in the arm
Muscles acting in coordinated fashion

Motor unit

A motor neuron and the skeletal muscle fibres it controls .
- A motor neuron can innervate many muscle fibers
- A motor unit is the basic functional unit of contraction
Contraction is initiated when a somatic motor neuron fires an action potential, causing all muscle fibers in the motor unit to contract.

Basic Mechanics of Body Movement

Isotonic contractions: Muscle contracts, shortens, and/or moves a load (e.g., picking up a weight)
Isometric contractions: Muscle contracts but does not change length and does not move a load (e.g., holding a weight)

Bones and Muscles Around Joints (levers)

Lever: A rigid bar that pivots around a point (fulcrum)
Fulcrum: The flexible joint that forms the pivot point.
Load: Object pulled or pushed during movement.
Muscle force: Muscles attached create this force by contracting.
Lever systems: Bones act as levers, joints are fulcrums, and muscles provide force.

Classification of Joints

Fibrous joints: Held together by dense connective tissue.
- Gomphoses (e.g., teeth)
- Sutures (e.g., skull)
- Syndesmoses (e.g., tibia/fibula connection)
Cartilaginous joints: Joined by cartilage, lack a joint cavity.
- Synchondroses (e.g., epiphyseal plate)
- Symphyses (e.g., pubic symphysis)
Synovial joints: Has a fluid-filled synovial cavity between articulating bones; enclosed in a capsule and joined by ligaments
Synarthrosis: An immovable joint (e.g., suture of skull)
Amphiarthrosis: A slightly movable joint (e.g., symphysis pubis)
Diarthrosis: A freely movable joint (e.g., elbow joint)

Accessory Structures of Synovial Joints

Bursae: Fibrous sacs that contain synovial fluid reduce friction
Fat pads: Found around synovial joints act as packing material

Types of Synovial Joints

Classified by their shape:
Plane or gliding: Flat or slightly curved surfaces, small movements (e.g., intercarpal)
Hinge: Convex and concave surfaces, one axis of movement (e.g., elbow)
Pivot: Cylindrical surface rotating within a ring (e.g., proximal radioulnar)
Ellipsoid/condyloid: Oval articular surface within a depression, two axes of movement (e.g., wrist between radius & carpals)
Saddle: Articular surfaces with both a concave & convex region, two axes of movement (e.g., carpometacarpal of thumb)
Ball-and-socket: Spherical head fits within a cup-shaped socket, multiaxial movement (e.g., shoulder)

Other details

Sinuses: Hollows within bones in the skull that are lined with mucous membranes, lighten skull, serve as resonant chambers for voice.
Hyoid bone: U-shaped bone located in the neck; does not articulate directly with other bones in the skeleton; provides sites for attachment of ligaments and muscles of the neck and tongue

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on bone types, cells, and structures with this quiz. Questions cover the shape, function, and composition of bones as well as key processes like ossification. Ideal for students studying anatomy and physiology.