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

34

5

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.