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Questions and Answers
What is the primary function of cartilage in the skeletal system?
What is the primary function of cartilage in the skeletal system?
Which type of bone tissue is known for its density and strength?
Which type of bone tissue is known for its density and strength?
Which of the following bone shapes is categorized as 'irregular'?
Which of the following bone shapes is categorized as 'irregular'?
What type of bone formation occurs via the transformation of cartilage to bone?
What type of bone formation occurs via the transformation of cartilage to bone?
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Which connective tissue attaches bone to bone?
Which connective tissue attaches bone to bone?
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What is the first step in the process of bone repair following a fracture?
What is the first step in the process of bone repair following a fracture?
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What happens to long bones at the epiphyseal plate during infancy and youth?
What happens to long bones at the epiphyseal plate during infancy and youth?
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Which hormone is primarily responsible for calcium regulation in bone homeostasis?
Which hormone is primarily responsible for calcium regulation in bone homeostasis?
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What is the composition of yellow marrow in adults?
What is the composition of yellow marrow in adults?
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What occurs at the epiphyseal plate when growth in length of the bone has completed?
What occurs at the epiphyseal plate when growth in length of the bone has completed?
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What do osteoclasts do during bone remodeling?
What do osteoclasts do during bone remodeling?
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Which type of marrow is primarily responsible for blood cell formation?
Which type of marrow is primarily responsible for blood cell formation?
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What is the function of the vertebral column?
What is the function of the vertebral column?
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What is a foramen in bone anatomy?
What is a foramen in bone anatomy?
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Which section of the vertebral column contains the most vertebrae?
Which section of the vertebral column contains the most vertebrae?
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Which type of joint is described as nonmovable?
Which type of joint is described as nonmovable?
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What is the role of the external auditory meatus?
What is the role of the external auditory meatus?
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Which of the following bones is part of the pectoral girdle?
Which of the following bones is part of the pectoral girdle?
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Where is the acetabulum located?
Where is the acetabulum located?
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Which bones are classified as the lower limb bones?
Which bones are classified as the lower limb bones?
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What is the main function of the epiphyseal plate?
What is the main function of the epiphyseal plate?
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What type of rib attaches directly to the sternum via cartilage?
What type of rib attaches directly to the sternum via cartilage?
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What distinguishes spongy bone tissue from compact bone tissue?
What distinguishes spongy bone tissue from compact bone tissue?
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Which bone cells are primarily responsible for breaking down bone tissue?
Which bone cells are primarily responsible for breaking down bone tissue?
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What is the primary ossification center responsible for?
What is the primary ossification center responsible for?
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Where is the medullary cavity located and what does it contain?
Where is the medullary cavity located and what does it contain?
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What is the role of osteoblasts in bone formation?
What is the role of osteoblasts in bone formation?
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What is a key characteristic of canaliculi?
What is a key characteristic of canaliculi?
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Which type of ossification occurs inside cartilage?
Which type of ossification occurs inside cartilage?
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Study Notes
Skeletal System Functions
- Provides support for the body.
- Protects internal organs.
- Facilitates movement.
- Stores minerals like calcium.
- Produces blood cells.
Skeletal System Components
- Bone: The hard, dense tissue that forms the skeletal framework.
- Cartilage: A flexible connective tissue that reduces friction in joints and serves as a model for bone formation.
- Tendons: Tough, fibrous cords that attach muscles to bones.
- Ligaments: Strong, elastic bands of tissue that connect bones to each other.
Classification of Bones
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Based on shape:
- Long Bones: Longer than they are wide, with a shaft and two ends. Examples: femur, tibia, fibula.
- Short Bones: Cube-shaped bones. Examples: carpals, tarsals.
- Flat Bones: Thin, flattened bones with a curved surface. Examples: ribs, sternum, skull bones.
- Irregular Bones: Have a varied shape that does not fit into the other categories. Examples: vertebrae, facial bones.
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Based on tissue type:
- Compact (Cortical) Bone: Dense, hard outer layer of bones.
- Spongy (Cancellous) Bone: Porous, lighter bone found at the ends of long bones and inside flat bones.
Compact Bone Tissue
- Found on the outside of the diaphysis (shaft) of long bones and the thinner surfaces of other bones.
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Osteon: Structural unit of compact bone, consisting of:
- Lamellae: Concentric rings of bone matrix.
- Lacunae: Small spaces between lamellae that house osteocytes.
- Canaliculi: Tiny canals that connect lacunae, allowing for nutrient transport and waste removal.
- Central Canal: The center of the osteon, containing blood vessels and nerves.
Spongy Bone Tissue
- Found in the epiphyses of long bones, the center of other bones, and inside flat bones.
- Composed of trabeculae: interconnecting rods and plates that form a latticework structure.
- Spaces between the trabeculae are filled with bone marrow.
- Does not contain true osteons.
Bone Cells
- Osteocytes: Mature bone cells responsible for maintaining the bone matrix.
- Osteoblasts: Bone-building cells that deposit new bone matrix.
- Osteoclasts: Bone-resorbing cells responsible for breaking down bone tissue.
Bone Formation (Ossification)
- Intramembranous Ossification: Bone formation directly within connective tissue membranes, occurs mostly in the flat bones of the skull.
- Endochondral Ossification: Bone formation that occurs within cartilage models. This process forms most bones in the body.
Endochondral Ossification Steps
- Step 1: Cartilage model formation: Chondroblasts form a cartilage model.
- Step 2: Calcification of cartilage: The cartilage model hardens.
- Step 3: Osteoblasts invade and form the primary ossification center in the diaphysis.
- Step 4: Secondary ossification centers form in the epiphyses.
- Step 5: Cartilage is replaced by bone, except for articular cartilage and the epiphyseal plate.
Bone Growth
- Longitudinal Growth: Occurs at the epiphyseal plate, a region of cartilage between the diaphysis and epiphysis.
- Appositional Growth: Occurs through the deposition of new bone matrix by osteoblasts on the surface of the bone, increasing bone width.
- Epiphyseal Plate closure: At the end of growth, the epiphyseal plate is replaced by the epiphyseal line, marking the end of bone growth in length.
Bone Remodeling
- Continuous process of bone breakdown (resorption) by osteoclasts and bone formation (deposition) by osteoblasts .
- In response to stress, bone shape changes, bone repair, and calcium homeostasis.
Bone Repair
- Step 1: A blood clot forms at the fracture site.
- Step 2: A fibrous callus forms, bridging the gap between the bone fragments.
- Step 3: A cartilaginous callus forms, gradually replaced by cancellous bone.
- Step 4: Remodeling occurs, transforming the cancellous bone into compact and cancellous bone.
Calcium Homeostasis
- Bone serves as a major storage site for calcium.
- Parathyroid hormone (PTH) increases blood calcium levels by stimulating osteoclast activity and promoting calcium reabsorption in the kidneys.
- Calcitonin decreases blood calcium levels by inhibiting osteoclast activity and promoting calcium deposition in bone.
Hematopoietic Tissue
- Responsible for blood cell production.
- Red Marrow: Found in the epiphyses of long bones and in other bones, produces all types of blood cells.
- Yellow Marrow: Mainly composed of fat, located in the medullary cavity of long bones in adults.
Bone Anatomy
- Foramen: A hole in a bone. Example: foramen magnum.
- Fossa: A depression in a bone. Example: glenoid fossa.
- Process: A projection or outgrowth from a bone. Example: mastoid process.
- Condyle: A smooth, rounded articular surface at the end of a bone. Example: occipital condyle.
- Meatus: A canal-like passageway in a bone. Example: external auditory meatus.
- Tubercle: A small, knob-like projection on a bone. Example: greater tubercle.
Axial Skeleton
- Mastoid Process: Attaches to neck muscles.
- External Auditory Meatus: Ear canal.
- Nasolacrimal Canal: Passageway between the nasal cavity and the eye, conducts tears.
- Styloid Process: Attachment site for tongue muscles.
- Mandibular Fossa: Depression where the lower jaw meets the skull.
- Glenoid Fossa: Depression where the humerus articulates with the scapula.
- Hard Palate: Roof of the mouth.
- Foramen Magnum: Hole where the spinal cord joins the brainstem.
- Zygomatic Bone: Cheek bone.
- Mandible: Lower jaw.
- Maxilla: Upper jaw.
Vertebral Column
- 7 cervical vertebrae (neck).
- 12 thoracic vertebrae (thorax).
- 5 lumbar vertebrae (lower back).
- 1 sacrum (fused vertebrae at the base of the spine).
- 1 coccyx (tailbone, fused vertebrae).
- Atlas: First cervical vertebra, supports the head.
- Axis: Second cervical vertebra, allows for head rotation.
Vertebral Column Functions
- Supports the body's weight and maintains posture.
- Protects the spinal cord.
- Allows for a wide range of movement.
Thoracic Cage
- Protects vital organs such as the heart and lungs.
- Composed of 12 pairs of ribs, the sternum (breastbone), and the thoracic vertebrae.
- True Ribs: Connect directly to the sternum by costal cartilage.
- False Ribs: Connect indirectly to the sternum by shared costal cartilage.
- Floating Ribs: Do not attach to the sternum.
Pectoral Girdle
- Connects the upper limbs to the axial skeleton.
- Composed of the scapula (shoulder blade) and the clavicle (collar bone).
Upper Limb Bones
- Humerus: Bone of the upper arm.
- Ulna: Bone of the forearm, located on the pinky finger side.
- Radius: Bone of the forearm, located on the thumb side.
- Carpals: Bones of the wrist.
- Metacarpals: Bones of the hand.
- Phalanges: Bones of the fingers and toes.
Pelvic Girdle
- Connects the lower limbs to the axial skeleton.
- Composed of two hip bones (ilium, ischium, and pubis).
- Acetabulum: Hip socket, where the femur articulates with the pelvis.
Lower Limb Bones
- Femur: Bone of the thigh.
- Patella: Knee cap.
- Tibia: Larger bone of the lower leg, located on the big toe side.
- Fibula: Smaller bone of the lower leg, located on the little toe side.
- Tarsals: Bones of the ankle.
- Metatarsals: Bones of the foot.
- Phalanges: Bones of the toes.
Articulations (Joints)
- Synarthrosis: Immovable joints. Example: sutures of the skull.
- Amphiarthrosis: Slightly movable joints. Example: joints between vertebrae.
- Diarthrosis: Freely movable joints. Example: shoulder, knee, hip joints.
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Description
Test your knowledge on the skeletal system, covering its various functions, components, and classifications of bones. This quiz will help you understand how the skeletal system supports the body, protects organs, facilitates movement, and more.
