© 2012 Pearson Education, Inc. Concepts and Current Issues Human Biology Sixth Edition Michael D....

© 2012 Pearson Education, Inc.

Concepts and Current Issues

Human BiologyS

ixth

Edi

tion

Michael D. Johnson

Lecture PresentationSuzanne Long

Monroe Community College

Chapter 5

The Skeletal System


Skeletal System: Made of Connective Tissue

• The skeletal system is made up of three types of connective tissue– Bone– Ligaments– Cartilage


Bones – Functions

• Bones: hard elements of the skeleton

• Five important functions1. Support

2. Protection

3. Movement

4. Blood cell formation

5. Mineral storage• Calcium• Phosphate


Bone – Structure

• Bone: hard inorganic matrix of calcium salts & collagen fibers)– Compact bone: forms shaft and ends– Spongy bone: red marrow is found here– Cells: osteoblast (makes new bone matrix),

osteocytes (maintains the bone matrix), osteoclasts (breaks down bone matrix)

– Bone shapes: long, short, flat, irregular

• Periosteum: connective tissue covering the outside of the bone


Epiphysis

Diaphysis

Epiphysis

a) A partial cut through a long bone. b) A closer view of a section of bone. Compact bone is a nearly solid structure with central canals for the blood vessels and nerves.

Blood vessels andnerve in central canal

Compact bone

Spongy bone

Spongy bone (spaces contain red bone marrow)

Compact bone

Yellow bone marrow

Blood vessel

Central cavity (contains yellow bone marrow)

Periosteum

d) A single osteocyte in a lacuna. Osteocytes remain in contact with each other by cytoplasmic extensions into the canaliculi between cells.

Osteocyte

Lacuna

Canalicula

Central canal

Osteon

Osteocytes

c) A photograph of an osteon of compact bone showing osteocytes embeded within the solid structure.

Osteon

Osteoblasts

Figure 5.1

© 2012 Pearson Education, Inc. Figure 5.1a

Epiphysis

Diaphysis

Spongy bone (spaces contain red bone marrow)

Compact bone

Yellow bonemarrow

Blood vessel

Periosteum

Central cavity(contains yellow bone marrow)

Epiphysis

a) A partial cut through a long bone.

© 2012 Pearson Education, Inc. Figure 5.1b

Osteon

Spongy bone

Compact bone

Osteoblasts

Blood vessels and nerve in central canal

b) A closer view of a section of bone. Compact bone is a nearly solid structure with central canals for the blood vessels and nerves.


Cartilage and Ligaments

• Cartilage– Function: support– Types

• Fibrocartilage (menisci of knee, intervertebral discs)

• Hyaline (most cartilage is of this type)• Elastic cartilage (ears, epiglottis)

• Ligaments– Function: attach bone to bone– Dense fibrous connective tissue


Bone Development

• Early fetal development: cartilage model– Formed by chondroblasts (cartilage-forming

cells)

• Later fetal development: osteoblasts replace cartilage with bone

• Childhood: primary and secondary ossification sites formed

• Adolescence: elongation at growth plates

© 2012 Pearson Education, Inc. Figure 5.2

Fetus: First2 months Developing

periosteum

Blood vessel

Fetus: At 2–3 months

Childhood

Adolescence

Cartilage growth plate

Compact bone containing osteocytes

Cartilage growth plate

a) Chondroblasts form hyaline cartilage, creating a rudimentary model of future bone.

b) The periosteum begins to develop and cartilage starts to dissolve. Newly developing blood vessels transport osteoblasts into the area from the periosteum.

c) Osteoblasts secrete osteoid and enzymes, facilitating the deposition of hard hydroxyapatite crystals.

d) The growth plates in long bones move farther apart and osteoblast activity continues just below the periosteum. The bone lengthens and widens.


Growth plate

Jointcartilage

Chondroblasts deposit newcartilage at the outer surface

Osteoblastsconvert cartilageto bone at theinner surface


Bone Growth


Hormonal Control of Bone Growth

• Preadolescence – Growth hormone stimulates bone

lengthening

• Early Adolescence– Estrogen and testosterone stimulate bone

lengthening

• Late Adolescence – Estrogen and testosterone cause

replacement of cartilage growth plates with bone


Cells Involved in the Development and Maintenance of Bone

• Chondroblasts: cartilage-forming cells

• Osteoblasts: young bone-forming cells

• Osteocytes: mature bone cells

• Osteoclasts: bone-dissolving cells


Mature Bone Remodeling and Repair

• Changes in shape, size, strength– Dependent on diet, exercise, age

• Bone cells regulated by hormones– Parathyroid hormone (PTH): removes calcium

from bone– Calcitonin: adds calcium to bone

• Repair: hematoma and callus formation


Bone removed here

New boneadded here

Compressive force

a) The application of force to a slightly bent bone produces a greater compressive force on the inside curvature. Compressive force produces weak electrical currents which stimulate osteoblasts.

(b) Over time, bone is deposited on the inside curvature and removed from the outside curvature.

c) The final result is a bone matched to the compressive force to which it is exposed.


Bone Repair


Human Skeleton

• 206 bones

• Axial skeleton– Skull, vertebral column, sternum, ribs

• Appendicular skeleton– Pectoral girdle, pelvic girdle, limbs


Axial skeleton

Cranium (skull)MaxillaMandible

Sternum

Vertebrae

Sacrum

Appendicular skeleton

Clavicle

Humerus

UlnaRadiusCarpals

Metacarpals

Phalanges

Coxal bone

PatellaTibiaFibula

TarsalsMetatarsalsPhalanges

Ribs

Scapula

Femur


Temporal bone

Frontal bone

Sphenoid bone

Ethmoid bone

Lacrimal bone

Nasal bone

Zygomatic bone

Maxilla

Mandible

Maxilla

Zygomatic bonePalatine bone

Sphenoid bone

Foramen magnum

Occipital bone

Parietal bone

Occipitalbone

External auditorymeatus

Vomer bone


Cervical vertebrae (7)

Thoracicvertebrae (12)

Lumbar vertebrae(5)

Sacrum(5 fused)

Coccyx (4 fused)

12

34567

123

45

6

7

8

9

10

11

12

1

2

3

4

5


Axial Skeleton: Vertebral Column (cont.)

• Vertebral column– Regions: cervical, thoracic, lumbar, sacral,

coccygeal– Intervertebral disks: cushion vertebrae; assist

in movement and flexibility

• Ribs– Twelve pairs– Bottom two pair floating

• Sternum: breastbone– Three bones fused together


Spinal cord

Intervertebraldisk

Main bodiesof vertebrae

b) A herniated disk.

Articulations with another vertebra

Spinal nerve

Articulation with ribs

a) Healthy disks.

Herniated areapressing againsta nerve


Spinal cord

Articulationswith anothervertebra

Spinal nerve

Articulation with ribs

a) Healthy disks.

Main bodies of vertebrae

Intervertebral disk


Herniated areapressing againsta nerve

b) A herniated disk.


Sternum (breastbone)

Ribs

Cartilage

Vertebral column

Floating ribs

T11

T12

L1

L2

12

11

C7

T1 1

2

3

4

5

6

7

8910


Appendicular Skeleton

• Pectoral girdle: shoulder– Clavicle and scapulas

• Pelvic girdles: hip– Coxal bones, sacrum, pubic symphysis

• Limbs– Arms: humerus, radius, ulna, wrist and hand

bones– Legs: femur, tibia, fibula, ankle and foot bones


Pectoral girdle

Clavicle(collar bone)

Scapula (shoulder blade)

Humerus(upper arm)

Ulna

Forearm

Radius

8 Carpals (wrist)

5 Metacarpals (hand)

14 Phalanges (finger bones)


Coxal bones and sacrum (pelvis)

Femur (upper leg)

Patella (knee cap)

Lower legTibia

Fibula

7 Tarsals (ankle)5 Metatarsals (foot)

14 Phalanges (toe bones)

Pubic symphysis

sacrum


Joints (Articulations)

• Classified by degree of movement– Fibrous joint: immovable (e.g., sutures of

the skull)

– Cartilaginous joint: slightly movable, cartilage connection (e.g., pubic symphysis)

– Synovial joint: freely movable


b) A view of the knee with muscles, tendons, and ligaments in their normal position surrounding the intact joint capsule. The combination of ligaments, tendons, and muscles holds the knee tightly together.

Ligaments

Joint capsule

Tendon

Thigh muscles

Patella

Ligaments

a) A cutaway anterior view of the right knee with muscles, tendons, and the joint capsule removed and the bones pulled slightly apart so that the two menisci are visible.

Tendon

Patella

LigamentTibia

Fibula

Femur

Ligament

Meniscus

Hyaline cartilage

Posterior cruciate ligament

Anterior cruciate ligament

Meniscus


Femur

Ligament

Meniscus

Fibula

Tibia

Tendon

Patella

Ligament

Hyaline cartilage

Posterior cruciate ligamentAnterior cruciate ligamentMeniscus

a) A cutaway anterior view of the right knee with muscles, tendons, and the joint capsule removed and the bones pulled slightly apart so that the two menisci are visible.


Thighmuscles

Tendon

Joint capsule

Ligaments

Patella

Ligaments

b) A view of the knee with muscles, tendons, and ligaments in their normal position surrounding the intact joint capsule. The combination of ligaments, tendons, and muscles holds the knee tightly together.


Synovial Joints

• Joint capsule: synovial membrane

• Synovial membrane secretes synovial fluid as a lubricant

• Hyaline cartilage acts as a cushion

• Types of synovial joints– Hinge joint– Ball and socket joint

• Tendons – join bone to muscle

• Ligaments-join bones to each other


Supination: Rotation of theforearm so palmfaces anteriorly.

d) Supination and pronation.

Pronation:Rotation of theforearm so palmfaces posteriorly

Humerus

Ulna

Radius Radius

Abduction:Movement of a limb away from a body’s midline

Adduction:Movement of a limbtoward the body’smidline

Abduction

AdductionAbduction

Adduction

a) Abduction and adduction.

Adduction

Abduction

Rotation:Movement of a body part around its own axis

Circumduction:Movement of a limbso that it describesa cone

b) Rotation and circumduction.

Flexion:Decreases the angle of a joint

Flexion

Extension

Hyperextension

Flexion Hyperextension:Extension beyondthe anatomicalposition

Extension

Flexion

ExtensionExtension:Increases the angle of a joint

c) Flexion, extension, and hyperextension.

Hyperextension

Imaginary cone off movement

Ulna


Abduction: Movement of alimb away from a body’s midline

Adduction:Movement of a limbtoward the body’smidline

Abduction

Adduction

Abduction

Abduction

Adduction

Adduction

a) Abduction and adduction.


Circumduction:Movement of a limbso that it describesa cone

Rotation:Movement of a body part around its own axis

Imaginary cone of movement

b) Rotation and circumduction.

© 2012 Pearson Education, Inc. Figure 5.13c

Flexion:Decreases the angle of a joint

Flexion

Extension

Hyperextension

Flexion

Flexion

Extension

Hyperextension

ExtensionExtension:Increases the angle of a joint

Hyperextension:Extension beyondthe anatomicalposition

c) Flexion, extension, and hyperextension.

© 2012 Pearson Education, Inc. Figure 5.13d

Supination:Rotation of theforearm so palmfaces anteriorly

Pronation:Rotation of theforearm so palmfaces posteriorly

Ulna

Radius

Humerus

Ulna

Radius

d) Supination and pronation.


Diseases and Disorders of the Skeletal System

• Sprains: stretched or torn ligaments

• Bursitis and tendinitis: inflammations

• Arthritis: inflammation of joints– Osteoarthritis– Rheumatoid arthritis

• Osteoporosis: excessive bone loss

© 2012 Pearson Education, Inc. Concepts and Current Issues Human Biology Sixth Edition Michael D....

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