Podcast
Questions and Answers
What type of bone is roughly cube-shaped and includes the bones of the wrist and ankle?
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?
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?
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?
Which type of bone are vertebrae classified as?
What role do osteoblasts serve in bone health?
What role do osteoblasts serve in bone health?
Which bone structure is primarily responsible for maintaining bone tissue?
Which bone structure is primarily responsible for maintaining bone tissue?
What is the primary composition of bone tissue?
What is the primary composition of bone tissue?
Which component of bone cells promotes the digestion of bone matrix?
Which component of bone cells promotes the digestion of bone matrix?
What forms the embryonic skeleton before week 8?
What forms the embryonic skeleton before week 8?
Which process describes the replacement of hyaline cartilage with bone?
Which process describes the replacement of hyaline cartilage with bone?
Which of the following bones are formed through intramembranous ossification?
Which of the following bones are formed through intramembranous ossification?
What are mesenchymal cells before they differentiate into osteoblasts during ossification?
What are mesenchymal cells before they differentiate into osteoblasts during ossification?
What is the ossification center?
What is the ossification center?
What is primarily produced during the initial stages of intramembranous ossification?
What is primarily produced during the initial stages of intramembranous ossification?
What is one main requirement for osteoblasts during their activity in ossification?
What is one main requirement for osteoblasts during their activity in ossification?
Which type of bone development is more complex, involving the breakdown of existing cartilage?
Which type of bone development is more complex, involving the breakdown of existing cartilage?
What is the primary function of T-tubules in muscle fibers?
What is the primary function of T-tubules in muscle fibers?
Which proteins are primarily involved in muscle contraction?
Which proteins are primarily involved in muscle contraction?
What role does the heavy chain of myosin play in muscle contraction?
What role does the heavy chain of myosin play in muscle contraction?
How are thick filaments structured in skeletal muscle?
How are thick filaments structured in skeletal muscle?
What type of protein is G-actin, and how does it usually exist in muscle fibers?
What type of protein is G-actin, and how does it usually exist in muscle fibers?
What is the significance of the myosin-binding site on G-actin?
What is the significance of the myosin-binding site on G-actin?
What structural arrangement do thin filaments exhibit in a myofibril?
What structural arrangement do thin filaments exhibit in a myofibril?
Which accessory proteins are linked to the structure of myofibrils?
Which accessory proteins are linked to the structure of myofibrils?
What occurs to chondrocytes near the center of the cartilage model as they enlarge?
What occurs to chondrocytes near the center of the cartilage model as they enlarge?
What is formed when blood vessels grow into the perichondrium surrounding the cartilage shaft?
What is formed when blood vessels grow into the perichondrium surrounding the cartilage shaft?
What does the presence of osteoclasts accomplish during endochondral ossification?
What does the presence of osteoclasts accomplish during endochondral ossification?
What defines the primary ossification center in the context of endochondral ossification?
What defines the primary ossification center in the context of endochondral ossification?
Around birth, most long bones have which of the following characteristics?
Around birth, most long bones have which of the following characteristics?
What triggers the differentiation of fibroblasts into osteoblasts during endochondral ossification?
What triggers the differentiation of fibroblasts into osteoblasts during endochondral ossification?
During endochondral ossification, what primarily happens to the cartilage model as growth occurs?
During endochondral ossification, what primarily happens to the cartilage model as growth occurs?
What happens to the epiphyseal cartilage during endochondral ossification while the diaphysis is elongating?
What happens to the epiphyseal cartilage during endochondral ossification while the diaphysis is elongating?
What happens to the length of the A band during muscle contraction?
What happens to the length of the A band during muscle contraction?
What initiates the power stroke in muscle contraction?
What initiates the power stroke in muscle contraction?
What is the role of ATP in muscle contraction?
What is the role of ATP in muscle contraction?
What occurs to the I band and H zone during muscle contraction?
What occurs to the I band and H zone during muscle contraction?
What happens to myosin heads after completing a power stroke?
What happens to myosin heads after completing a power stroke?
How does myosin act as an ATPase during muscle contraction?
How does myosin act as an ATPase during muscle contraction?
What does the term 'cocked' refer to in myosin heads?
What does the term 'cocked' refer to in myosin heads?
What is the primary function of the sliding filament theory?
What is the primary function of the sliding filament theory?
What role does troponin play in muscle contraction?
What role does troponin play in muscle contraction?
What must occur for tropomyosin to shift to the 'on' position?
What must occur for tropomyosin to shift to the 'on' position?
What happens when calcium concentration in the cytosol decreases?
What happens when calcium concentration in the cytosol decreases?
What is the rigor state in muscle contraction?
What is the rigor state in muscle contraction?
What is the effect of ATP binding on the myosin head?
What is the effect of ATP binding on the myosin head?
During which phase does myosin bind to a new actin molecule after ATP hydrolysis?
During which phase does myosin bind to a new actin molecule after ATP hydrolysis?
What is the primary trigger for the muscle contraction process to initiate?
What is the primary trigger for the muscle contraction process to initiate?
What allows the contractile cycle to repeat during muscle contraction?
What allows the contractile cycle to repeat during muscle contraction?
Flashcards
Intramembranous Ossification
Intramembranous Ossification
The process of bone formation from fibrous membranes.
Endochondral Ossification
Endochondral Ossification
The process of bone formation from hyaline cartilage.
Mesenchyme
Mesenchyme
Embryonic connective tissue that forms the basis for intramembranous ossification.
Ossification Center
Ossification Center
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Osteoblasts
Osteoblasts
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Osteocytes
Osteocytes
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Spicules
Spicules
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Periosteum
Periosteum
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Long Bones
Long Bones
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Short Bones
Short Bones
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Flat Bones
Flat Bones
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Irregular Bones
Irregular Bones
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Osteoprogenitor Cells
Osteoprogenitor Cells
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What happens to chondrocytes during endochondral ossification?
What happens to chondrocytes during endochondral ossification?
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Why do chondrocytes die during endochondral ossification?
Why do chondrocytes die during endochondral ossification?
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How does the perichondrium contribute to endochondral ossification?
How does the perichondrium contribute to endochondral ossification?
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Describe the process of bone formation during endochondral ossification.
Describe the process of bone formation during endochondral ossification.
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What happens to the primary ossification center and epiphyseal cartilage during endochondral ossification?
What happens to the primary ossification center and epiphyseal cartilage during endochondral ossification?
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Describe the state of long bones around birth during endochondral ossification.
Describe the state of long bones around birth during endochondral ossification.
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What is endochondral ossification?
What is endochondral ossification?
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What are the key stages of endochondral ossification?
What are the key stages of endochondral ossification?
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What are T-tubules?
What are T-tubules?
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What's found in the cytosol of a muscle fiber?
What's found in the cytosol of a muscle fiber?
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What are myofibrils?
What are myofibrils?
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Describe myosin's structure and function.
Describe myosin's structure and function.
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What are the key functions of myosin head?
What are the key functions of myosin head?
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How do myosin molecules form thick filaments?
How do myosin molecules form thick filaments?
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What is actin and how does it form thin filaments?
What is actin and how does it form thin filaments?
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What are crossbridges and how are they formed?
What are crossbridges and how are they formed?
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Sliding Filament Theory
Sliding Filament Theory
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Sarcomere
Sarcomere
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Actin Filaments
Actin Filaments
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Myosin Filaments
Myosin Filaments
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Myosin Crossbridges
Myosin Crossbridges
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Power Stroke
Power Stroke
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Myosin ATPase
Myosin ATPase
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Cocked Myosin
Cocked Myosin
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Rigor State
Rigor State
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Troponin
Troponin
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Tropomyosin
Tropomyosin
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Myosin-Binding Site
Myosin-Binding Site
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Myosin Head Cycle
Myosin Head Cycle
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Muscle Relaxation
Muscle Relaxation
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Tropomyosin Positioning
Tropomyosin Positioning
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Calcium Signal
Calcium Signal
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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:
- Â 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:Â Hollows within bones in the skull that are lined with mucous membranes, lighten skull, serve as resonant chambers for voice.
- Hyoid bone:Â 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
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