BIOL 102 Lecture 5 - 10 Notes

CHAPTER 5 --- Skeletal
Skeletal system: made of connective tissue
Bone: Hard inorganic matrix of calcium salts
 Compact: forms shaft and ends, contains marrow space (yellow marrow = fat
marrow)
 (Red marrow produces blood cells and is in the ends of the bones)
 Spongy: trabecular
 Cells
o Osteoblast (change cartilage into bone in the fetus)
o Osteocytes: Osteons/Haversian system: cellular arrangement
(mature bone cells that maintain the structure of bone)
o Osteoclast (bone-dissolving cells)
4 Types of Bones
 Long (limbs/finger)
 Short (bones of the wrist)
 Flat (sternum, ribs, cranial bones)
 Irregular (coxal)
Periosteum: CT covering
Diaphysis - outside hard part of yellow bone, blood vessel
Epiphysis - spongy bone/ red marrow
Cartilage and Ligaments
 Cartilage
o Function: support
o Types: fibrocartilage, hyaline, and elastic cartilage
 Ligaments: attach bone to bone
Bone Development
 Prenatal: cartilage model
 Fetus: some conversion to bone
 Childhood: primary and secondary ossification sites formed
 Adolescence: cartilage growth plate elongates
Mature Bone Remodeling and Repair
 Changes in shape, size, strength
o Dependent on diet, exercise, age
 Bone cells regulated by hormones
o Parathyroid hormone (PTH): removes calcium from bone
o Calcitonin: adds calcium to bone
 Repair: hematoma and callus formation
Human Skeleton
 206 bones
Axial Skeleton - skull, vertebral, column, ribs, sternum (anything attached to the
spine)
Appendicular Skeleton - Pectoral girdle, pelvic girdle, limbs
Functions of the skeletal system

,  Protection: encases most internal organs
 Support: allows body positions
 Permit movement: muscle attachments for movement
 Mineral Reservoir: calcium, phosphorus
Vertebral column
First 7: Cervical Vertebrae – (CV1-CV7)
 Smallest of the vertebrae
 Neck
 C1 called atlas – holds skulls up, nod
 C2 called axis – rotates head
Next 12: Thoracic Vertebrate – (T1-T12)
 Where ribs attach
Next 5: Lumbar Vertebrae
 Lower back
 Biggest 5
Next 5: Sacrum
 Lower back
Last 4: Coccyx
 Butt
Axial Skeleton
 Vertebral column
o Regions: cervical, thoracic, lumbar, sacral, coccygeal
o Intervertebral disks: cushion the vertebrae, assist in movement/
flexibility
 Ribs
o 12 Pairs
o Bottom two pair floating
 Sternum: breastbone
o 3 bones fused together
Appendicular Skeleton: Appendages, anything not attached to the spine
 Pectoral girdle: Shoulder
o Clavicle and scapula
 Pelvic girdle: hip:
o Coxal bones, sacrum, pubic symphysis

 Limbs
o Arms: humorous, radius, ulna, wrist and hand bones
o Legs: femur, tibia, fibula, ankle, and foot bones (fibula smaller than
tibia)
Joints (articulations)
 Classified by degree of movement
 Three types of joints
o Fibrous joint: immovable (fontanels)
o Cartilaginous joint: slightly movable, cartilage connection (backbone)
o Synovial joint: freely movable (hinge joint - knee, elbow)

, Synovial Joints
 Joint capsule: synovial membrane & hyaline cartilage
 Synovial membrane secretes synovial fluid as a lubricant
 Hyaline cartilage acts as a cushion
 Types of synovial joints
o Hinge joint
o Ball and socket joint
 Tendons: join bone to muscle
Diseases and Disorders of the Skeletal System
 Sprains: stretched or torn ligaments
 Bursitis and tendinitis: inflammations (itis means inflammation)
 Arthritis: inflammation of joints
o Osteoarthritis: wearing down of the joint
o Rheumatoid arthritis: due to allergy
 Osteoporosis: excessive bone loss


CHAPTER 6 --- Muscles
Muscle Function: Produce movement or generate tension
Principle Function
 Contraction: shortens the distance between bones
 Skeletal muscle moves bones
Muscle Groups
 Synergistic: groups work together
 Antagonistic: groups oppose each other
Muscle Structure
 Fasicles
o Bundles of muscle fibers wrapped with connective tissue (fascia)
 Muscle Fibers (muscle cells)
o Long, tube shaped cell
o Multinucleate
o Packed with myofibrils (smaller)
 Myofibrils contain actin & myosin (proteins)
Skeletal Muscle Contractive Unit
Sarcomere: Contractive Unit
 Myosin: Forms think filaments
 Actin: forms thin filaments
Z lines: attachment points for sarcomeres
 Arrangement of filaments gives rise to striated appearance of skeletal muscle
Nerve Activation of Individual Muscle Cells
 Acetylcholine released from motor neuron at neuromuscular junction
 Electrical impulse transmitted along T tubules
 Calcium released from sarcoplasmic reticulum