NervousSystem
Integumentary System
Skeletal SystemMuscular System
Circulatory System
Respiratory System
Digestive System
Excretory System
Endocrine System
Reproductive System
Lymphatic System
The Skeletal System
1. The Skeleton
2. Bone Structure
3. Bone Development
4. Joints
Skull
Sternum
Ribs
Vertebral column
Axial Skeleton - Supports the central axis of the body.
Metatarsals
Metacarpals
Phalanges
ClavicleScapula
Humerus
RadiusPelvisUlnaCarpals
Femur
Patella
FibulaTibiaTarsals
Phalanges
Appendicular Skeleton - The bones of the appendages (arms, shoulder area, legs, and pelvis).
The Human SkeletonThe adult human skeleton has 206 bones and is divided into two parts:
Functions of the Skeleton
• Support – hold up the body• Protection – rib cage, skull, and pelvic
girdle protect important organs• Movement – skeletal muscle attaches to
the bones of the skeleton to allow movement
• Storage – bones store fat, calcium, minerals
• Hematopoeisis – blood cell formation
Bone StructureBone - a solid network of living cells and fibers that are supported by deposits of calcium salts
Periosteum – tough layer of fibrous connective tissue that surrounds bone
Compact Bone – dense bone that makes up the bulk of the skeleton
Haversian Canals – canals that run through compact bone that contain blood vessels and nerves
Spongy Bone – porous bone found in the ends of long bones and in the middle of short and flat bones
Bone Marrow – found in the cavities of bones
Bone Marrow
• red marrow is in spongy bone– production of blood
cells
• yellow marrow is found in the central cavity of long bones– stores fat and acts as
an energy reserve
Cartilage• cushions the ends of
bones – elbows, hips, and
knees
• provides structure– nose and ears– much of a newborn's
skeleton is made of cartilage
Bone Development
• Cartilage pre-cursor – cartilage is slowly replaced by bone through a process called ossification
• Osteoblasts – bone forming cells• Osteoclasts – bone destroying cells• Osteocytes – regulate cellular activities of bone
Thought Question:
What disease is caused by an imbalance between Osteoblast and Osteoclasts?
Joints
• Ball and Socket Joint (shoulder) - bones can rotate while moving back and forth and side to side
• Hinge Joint (knee) - allows movement back and forth in one plane
• Pivot Joint (top of neck and base of skull) - one bone rotates around another
Ball-and-Socket Joint
Hinge Joint
Pivot Joint
Saddle Joint
Clavicle
Ball-and-socket joint
ScapulaHumerus
Femur
Patella
Hinge jointTibia
Fibula
Humerus
Radius
Pivot joint
Ulna
Metacarpals
CarpalsSaddle joint
Immovable – fibrous, fixed; example - skull bones
Slightly movable – cartilaginous; example – intervertebral discs
Freely movable – synovial; examples shown above
Joints
Muscle
Tendon
Femur
PatellaBursaLigamentSynovial fluidCartilage
Fat
Fibula
Tibia
Tendon - connective tissue attaching muscle and bone.
Ligament – connective tissue attaching bones
Thought Question:
Based on the diagram, what is the difference between a tendon and a ligament?
The Knee
The Muscular System
1. Types of Muscle Tissue
2. Muscle Contraction
3 Types of Muscle
•Skeletal •Cardiac•Smooth
Smooth Muscle
• Found in internal tubes and vessels – digestive and circulatory systems
• Moves food, blood, and other substances through the body
• Involuntary - not under conscious control
• Not striated• uninucleated
Cardiac Muscle
• The muscle of the heart
• Main function is to pump blood
• Striated • Involuntary
Skeletal Muscle• Attached to bones of
the skeleton• Allows for movement• Striated – alternating
light and dark bands• Voluntary – under
conscious control• Multinucleated• Also called muscle
fibers• Complete muscle tissue
= muscle fibers, connective tissues, blood vessels, and nerves
Can you identify the type of muscle shown below?
Skeletal muscle
Bundle of muscle fibers
Actin
Myosin
Sarcomere
Z disc
Muscle fiber (cell)
Myofibril
Muscle cells are bundled together and are surrounded by a connective sheath.
An individual muscle cell is a long fiber with many nuclei. Each muscle cell contains a central cable made of a rodlike structures called myofibrils
Myofibrils are composed of two types of protein, actin and myosin. They make up the light and dark bands in functional units called sarcomeres.
Structure of Skeletal Muscle
Relaxed Muscle
Contracted Muscle
Z disc Myosin Actin Z disc
Sarcomere
Cross-bridges Z disc
Movement of Actin FilamentActin
Binding sites
Cross-bridge
Myosin
myosin - thick filaments, have many bump-like projections called "heads"
actin - thin filaments, like a string of twisted beads, the ends of the actin strands are attached to Z lines
1. myosin heads attach to the actin filaments forming cross bridges
2. the heads of the myosin filaments “walk” along the actin filaments, pulling them toward the center of the sarcomere
How a Muscle Contracts
Click on the link below to view a video showing a muscle contract:
http://www.3dotstudio.com/zz.html
Thought Question:Based on the requirements necessary for muscle contraction, what organelle would you expect to find in high concentration in muscle cells?
Actin pulledCross-bridge releases actin
Cross-bridge changes shape
Myosin returns to original
shape
Myosin forms cross-bridge
with actin
2
1
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Muscle Contraction
When a muscle contracts, the heads of the myosin filaments “walk” along the actin filaments, pulling them toward the center of the sarcomere. As this occurs simultaneously in sarcomeres throughout the cell the muscle cell contracts.
Essays1. When a person decides to move, his skeletal muscles
contract. Explain how a muscle contracts by discussing:a) What the contractile/functional unit of a muscle is called.b) What two proteins are involved in muscle contraction.c) Discuss the steps of skeletal muscle contraction (use the
terms: Sarcomere, Actin, Myosin, Crossbridge, Z-Discs)
2. Explain how the human skeleton accomplishes the following functions: a) Allows movement, protects internal organs, store mineral reserves, and provide a site for blood cell formation. b.) Be sure to explain where in the bones these tasks occur. c.) Explain two diseases that disrupt homeostasis by preventing these functions.