Human Bio Lec Exam 2

SU25

Functions of the Skeletal System

1.  support

2.  protection

3.  movement

4.  electrolyte balance- calcium and phosphate

5.  pH balance-absorbs or releases alkaline salts

6.  Hemopoiesis- red marrow produces blood cells

Bone Cells

osteogenic cells

stem cells that divide to produce osteoblasts

Bone cells

osteoblasts

bone forming cells; synthesize the soft organic material of bone tissue

Bone cells

Osteocytes

osteoblasts that have become surrounded by matrix

Bone cells

osteoclast

bone dissolving cells; result from the fusion of stem cells

Bone or inorganic matter

is made up of 85% hydroxyapetite (crystalized calcium phosphate salt)

Canaliculi

connect osteocytes (lil bitty tunnels that connect the bone cells to each other)

Red bone marrow

is responsible for all blood cell formation (hemopoiesis)

Found in the skull, vertebrae, ribs, sternum, pelvis, and proximal heads of the humerus and femur (not the arms or legs mainly axial skeleton)

Intramembranous bone ossification

This is how the flat bones of the skull and a portion of the clavicle are developed

Bone that develops from sheets of mesenchyme is known as intramembranous ossification

Steps of endochondral bone formation

Be aware of the basics again we form rough outline of the bone out of highline cartilage put a little collar bone around that as a cartilage cells, die opens up a cavity in the middle of the bone osteoblast then start in the center of the diaphysis. It makes spongy bone working outwards then later they start converting the cartilage in the epiphysis Into spongy bone, leaving just a line of cartilage between the diaphysis and epiphysis called the growth plate that allows for bone growth.

Zone of reserve cartilage

hyaline cartilage

Zone of proliferation

chondrocytes multiply and arrange into columns

Zone of hypertrophy

chondrocytes enlarge

Zone of calcification

cartilage is calcified

Zone of bone deposition

osteoblasts convert to bone

hypocalcemia

(calcium too low) causes excessive excitability of nervous system and muscle spasms (possibly tetanus)

hypercalcemia

(too much) nerves and muscle are less responsive

Calcitonin

(thyroid gland) lowers blood calcium levels

a.  Inhibits osteoclasts

b.  Stimulates osteoblasts

Parathyroid Hormone (PTH)

increases blood calcium

a. increases osteoclast numbers and bone reabsorption

b.  Promotes calcium reabsorption by kidneys

c.  Inhibits osteoblasts

Calcium Homeostasis

Calcium is needed for nerve impulses, muscle contraction, blood clotting and exocytosis

Repair of Fractures -1

Hematoma formation

blood clot forms and vessels grow into clot

Macrophages, fibroblasts, osteoclasts, and osteogenic cells invade the area

Repair of Fractures -2

Formation of a soft callus

fibroblasts form collagen and chondroblasts produce fibrocartilage forming a soft callus

Repair of Fractures -3

Conversion to hard callus

osteoblasts produce a bony collar around the fracture (4-6 weeks)

Repair of Fractures -4

Remodeling

osteoclasts remove bone fragments and osteoblasts deposit spongy bone which is converted to compact bone

Osteoporosis

bones loose mass and become porous

arthrology

study of joints (structure, function, and dysfunction)

kinesiology

study of musculoskeletal movement

Fibrous joint (synarthroses)

bones are connected by collagen fibers

a.  Sutures- short fibers; little movement ex. skull

b. gomphosis- short fibers in tooth socket; little movement

c.  Syndesmosis- longer fibers; more movable ex. radius and ulna

Cartilaginous joints (amphiarthoses)

bones are connected by cartilage

a.  Syncrondosis- hyaline cartilage connects bones ex. ribs

b.  Symphyses- fibrocartilage connects bones ex. intervertebral disks

Synovial Joints (usually diarthroses)

contained within a fluid filled  capsule

a.  Ex. Jaw, elbow, hip, knee

Movements of Synovial Joints

Flexion, Extension, Hyperextension

Decreases angle of joint, Increases angle of joint, extreme extension of a joint beyond the zero position

Movements of Synovial Joints

Abduction, Adduction

1. moves part away from midsagittal line (in frontal plane)

2. moves part toward midsagittal line (in frontal plane)

Movements of Synovial Joints

Elevation and Depression

6. raises part vertically (in frontal plane)

7. lowers part vertically

Movements of Synovial Joints

Protraction and Retraction

1. anterior movement of a body part (in transverse plane)

2. posterior movement of part

Movements of Synovial Joints

Circumduction and Rotation

10. distal end of part moves in a circle

11. bone spins on an axis

Movements of Synovial Joints

Supination and Pronation

1. turns palms to face anteriorly or upward

2. turns palms to face posteriorly or downward

Movements of Synovial Joints

Dorsiflexion and Plantar flexion

14. toes elevated

15. toes point downward

Movements of Synovial Joints

Inversion and Eversion

1. soles face medially

2. soles face laterally