1. The Skeletal System

2. Functions Framework for support Transmits movement Maintains shape
Protects internal organs from mechanical injury
Contains and protects the red bone marrow, one of the hemopoietic (blood-forming) tissues
Mineral reservoir - storage site for excess calcium and phosphorus
Storage of fats – yellow marrow

3. Types of skeletons Fluid-filled body cavity (hydrostatic)
Fluid-filled closed chambers
Internal pressure generated by muscle contraction
E.g. sea anemone and worms

4. Types of skeletons Exoskeleton Arthropods
Hard segments covering muscles and visceral organs
Muscles are attached to the exoskeleton
Restricts growth and size of animal  molting

5. Types of skeletons Endoskeleton
Internal, often mineralized, connective tissue
Muscles on the outside
Cartilage – sharks and rays
Other vertebrates – cartilage is replaced by bone as embryo matures and develops

6. Bone Tissue Compact bone Spongy bone Periosteum
series of Haversian canals
concentric layers of bone cells (osteocytes)
new bone formed by osteocytes
Spongy bone
ends of long bones
less dense than compact bone
spongy bone of femur, humerus, and sternum contains red marrow
yellow marrow at center is used to store fats
Periosteum
outer layer of bone
rich in nerve endings, blood, and lymphatic vessels
inner portion forms new bone or modifies existing bone to meet new conditions

7. Appendicular and axial skeleton
Axial skeleton (80 bones)
axis of the body
support and protect the organs of the head, neck, and trunk
Skull
Sternum
Ribs
Vertebral Column + sacrum and coccyx
Appendicular skeleton (126 bones)
anchors appendages to the axial skeleton
Upper Extremities
Lower Extremities
Pectoral Girdle
Pelvic Girdle

8. Joints or articulations
Meeting of two bones
Types of joints
Immovable
Slightly movable
Freely movable

9. Types of bone cells Osteoblasts Osteocytes Osteoclasts
immature bone cells
manufacture hormones and enzymes that aid in bone mineralization
Osteocytes
mature osteoblasts that have migrated into lacunae (spaces)
form bone, maintain matrix, and act for calcium homeostasis
Osteoclasts
cells responsible for bone reabsorption and shaping
located on bone surfaces

10. Types of bones Long bones Short bones Flat bones Irregular bones
Long shaft (diaphysis)
Two joint surfaces (epiphyses)
Mostly compact bone
e.g. femur, tibia, fibula, radius, ulna,
Short bones
Cube-shaped, mostly spongy bone
e.g. bones of wrist and ankle, patella
Flat bones
Thin and curved
e.g. skull and sternum
Irregular bones
Irregular and complicated shapes
e.g. spine and hips

11. Bone formation
Intramembranous ossification  formation of the flat bones of the skull
Endochondral ossification  formation of long bones

12. Bone remodeling
Resorption of bone (by osteoclasts) followed by replacement of bones (by osteocytes)
Functions to regulate calcium levels, repair damaged bones, and shape and sculpt the skeleton during growth
Rate is regulated by parathyroid hormones (PTH) and Vitamin D

13. Disorders of the skeletal system
Osteoporosis
Reduced bone density leading to fractures
Rickets and osteomalacia
Softening of bones leading to deformations and fractures
Arthritis
Inflammation of joints
Bone fractures
Scoliosis

14. Muscular system Name 3 characteristics of muscle tissue.
Describe 3 types of muscle tissue according to location, structure, and nervous control.
Define the following terms: muscle fiber, myofibril, myofilament, sarcomere, actin, and myosin.
Describe the sliding-filament theory.
References?