1. Skeleto-muscular System
Biology 201 Organismal S&F
Dr. Tony Serino
Biology Department
Misericordia University

2. Skeletal System
Composed of mineralized CT and their supporting structures including: bone, cartilage, ligaments, tendons, and bursae
Functions: support, protection, homeostasis (specifically Ca++ regulation) and hempoiesis

3. General Osteology Composition
Cells –originate from mesechyme (undifferentiated mesodermal cells)
Extracellular Matrix
Ground substances: water, salts, cementing substances, glycoproteins
Fibers: collagen and elastin

4. Cartilage Avascular CT Appositional and interstitial growth possible
Perichondrium
Chondroblast
Lacuna
Chondrocyte
Matrix

5. Hyaline Cartilage
Most abundant form of cartilage, found in articular cartilages, ribs, tip of nose, tracheal rings, etc.
Ground substances dominate matrix with collagen outnumbering elastin fibers

6. Elastic Cartilage
Seen where structure needs to snap back to original shape
Located in pinna and epiglottis
Matrix dominated by elastin fibers

7. Fibrocartilage
Occurs where great strength is needed, collagen fibers dominate matrix
Located in slightly moveable joints; such as, vertebral discs and pubic symphysis

8. Cartilage in Adult

9. Bone Heavily mineralized CT Highly vascular
Principle storage area of Calcium
Provides strength and structural support to body

10. Long Bone Anatomy

11. Flat Bone Anatomy
Trabeculae

12. Bone Histology

13. Haversian System Lamellae

14. Ossification Development of bony tissues
First bone to form is woven (premature) bone
This is eventually replace by mature bone (compact or spongy bone)
Two methods for creating bones:
Intramembraneous (bone replaces mesoderm membrane)
Endochondral (bone replaces an intervening cartilage model)

15. Intramembranous Ossification (Membrane bone formation)

16. Endochondral Ossification (Replacement Bone formation)

17. Epiphyseal (Growth) Plate
Reserve Cartilage (distal perichondrium)
Proliferating Cartilage (Growth zone)
Hypertrophic zone (Transforming zone)
Calcified matrix (Osteogenic zone)

19. Fracture Healing

20. Osteoporosis
Normal
Osteoporotic

21. Muscular System Functions: Attributes:
Movement –generation of force and/or shortening
Maintenance of posture
Joint stabilization
Heat Generation
Attributes:
contractility, irritability, extensibility, and elasticity

22. Types of Muscle Cells Skeletal Muscle –voluntary, striated
Cardiac Muscle –involuntary, striated
Smooth Muscle –involuntary, no striations

23. Muscles wrapped with CT, that is continuous with tendon and periosteum

24. Antagonistic Muscle Arrangement
This arrangement plus the series elastic component allows the muscle to return to its original length.

25. Skeletal Muscle Cells
Long, cylindrical, non-branching, multinucleated
mcm wide and up to 35 cm long
Voluntary, no spontaneous depolarization normally
Contractile proteins (myosin & actin) arranged in bundles called myofibrils

26. Each myofibril consists of overlapping thick and thin filaments arranged in units called sarcomeres.

27. Muscle Contraction: Mechanical Events (Sliding Filaments)
When a neuron stimulates a muscle cell with acetylcholine, Calcium ions released from SR flood the myofibrils
This causes the thick and thin filaments to bind to each other (generates tension) and may cause them to slide past each other
This causes the sarcomere to shorten

28. Muscles are arranged as Motor Units
Motor Unit = 1 motor neuron + all the muscle fibers it controls (innervates)
The size of the motor unit depends on the degree of control needed in that particular whole muscle.

29. Cardiac Muscle
Striated, single nucleus, branched cells, connected together by intercalated discs (with many gap junctions)
Spontaneously contracts, needs no innervation, involuntary

30. Smooth Muscle
No sarcomeres, therefore, no striations, single nucleated, small spindle shaped cells
Spontaneously contracts, involuntary control, can remain contracted for long periods of time without fatiguing
Two types: Visceral (single unit) –united by gap junctions Multi-unit –needs innervations, behaves like skeletal muscle (Ex. Iris, Arrector pili muscle)