Muscular and Skeletal SystemsMuscular and Skeletal Systems

I. Muscular SystemI. Muscular System

A.A. TypesTypes

B.B. Major Major GroupsGroups

A. TypesA. Types

1)1) SkeletalSkeletal• Provide movement for the Provide movement for the

skeletonskeleton• Most are consciously controlled Most are consciously controlled

by the central nervous systemby the central nervous system• Contain striations Contain striations • Have many nucleiHave many nuclei• Function by nervous stimulationFunction by nervous stimulation

• Motor neurons connected to Motor neurons connected to musclemuscle

• Composition: Composition: many fibers many fibers stacked together in bundlesstacked together in bundles

Composition Muscles composed of bundles of fibers

• Within each bundle there are individual fibers containing:

• Myofibril – Organized filament made of thin and thick proteins

Actin – Protein component of thin filamentsMyosin – Protein component of thick filamentsSarcomere – Smallest contractile unit in muscle fiberZ Line – Dividing line between 2 sarcomeres

Relaxed Muscle

Contracted Muscle

Z line Myosin Actin Z line

Sarcomore

Cross-bridges Z line

Movement of Actin FilamentActin

Binding sites

Cross-bridge

Myosin

Figure 36-8 Muscle Contraction

Section 36-2

Relaxed Muscle

Contracted Muscle

Z line Myosin Actin Z line

Sarcomore

Cross-bridges Z line

Movement of Actin FilamentActin

Binding sites

Cross-bridge

Myosin

Figure 36-8 Muscle Contraction

Section 36-2

During muscle contraction, the knoblike head of a myosin filament attaches to a binding site on actin, forming a cross-bridge.

Relaxed Muscle

Contracted Muscle

Z line Myosin Actin Z line

Sarcomore

Cross-bridges Z line

Movement of Actin FilamentActin

Binding sites

Cross-bridge

Myosin

Figure 36-8 Muscle Contraction

Section 36-2

During muscle contraction, the knoblike head of a myosin filament attaches to a binding site on actin, forming a cross-bridge.

Powered by ATP, the myosin cross-bridge changes shape and pulls the actin filament toward the center of the sarcomere.

Relaxed Muscle

Contracted Muscle

Z line Myosin Actin Z line

Sarcomore

Cross-bridges Z line

Movement of Actin FilamentActin

Binding sites

Cross-bridge

Myosin

Figure 36-8 Muscle Contraction

Section 36-2

During muscle contraction, the knoblike head of a myosin filament attaches to a binding site on actin, forming a cross-bridge.

Powered by ATP, the myosin cross-bridge changes shape and pulls the actin filament toward the center of the sarcomere.

The cross-bridge is broken, the myosin binds to another site on the actin filament, and the cycle begins again.

2.2. Smooth MusclesSmooth Muscles

• Not under voluntary controlNot under voluntary control• Spindle-shaped Spindle-shaped • One nucleusOne nucleus• Not necessary for nervous Not necessary for nervous

stimulation to functionstimulation to function• Gap junctions allow impulse Gap junctions allow impulse

to travel from muscle-cell to to travel from muscle-cell to muscle-cellmuscle-cell

• Locations:Locations:• Lines hollow organs (except Lines hollow organs (except

heart)heart)• Lining of blood vesselsLining of blood vessels• EyesEyes

A. Types Cont.

3.3. Cardiac MuscleCardiac Muscle• Involuntary controlInvoluntary control• StriatedStriated• Usually one nucleus Usually one nucleus

but may have twobut may have two• Muscles are Muscles are

connected by gap connected by gap junctionsjunctions

• Found only in the Found only in the heartheart

BicepsDeltoid

Trapezius

PectoralTriceps

Abdominalis

TricepsDeltoid

Quadriceps

Gluteus Maximus

Gastrocnemius

Sartorius

Gastrocnemius

radialis

BicepsTrapezius

Hamstring

Latissimus

B. Major Groups

II. Skeletal SystemII. Skeletal System

A.A. StructureStructure

B.B. DevelopmentDevelopment

C.C. JointsJoints

D.D. Major BonesMajor Bones

E.E. MovementMovement

A. A. StructureStructure1.1. BonesBones

• Living cells and protein surrounded by calcium depositionLiving cells and protein surrounded by calcium deposition• Direct blood supplyDirect blood supply

• Periosteum – connective tissue surrounding bonePeriosteum – connective tissue surrounding bone• Bone Marrow Bone Marrow – cavity in bone containing soft tissue– cavity in bone containing soft tissue

• Red Marrow – Produces R.B.C.’s some W.B.C.’s and plateletsRed Marrow – Produces R.B.C.’s some W.B.C.’s and platelets• Yellow Marrow – Made of fat cellsYellow Marrow – Made of fat cells

• 2 Types2 Types• SpongySpongy

• Inner Layer of boneInner Layer of bone• Contains Red MarrowContains Red Marrow

• CompactCompact• Outer layerOuter layer

• Osteocytes – Mature Bone cellsOsteocytes – Mature Bone cells• Osteoclasts – Breakdown boneOsteoclasts – Breakdown bone• Osteoblasts – Create boneOsteoblasts – Create bone

Spongy Bone

Compact Bone

Periosteum

Bone

Marrow

Spongy Bone

Compact Bone

HaversianCanal

Osteocyte

Artery

VeinPeriosteum

B. DevelopmentB. Development

1.1. As We GrowAs We Grow• Embryonic Skeleton - Embryonic Skeleton - Primarily composed of cartilage (elastic Primarily composed of cartilage (elastic

tissue that does not contain blood vessels)tissue that does not contain blood vessels)

• Cartilage is replace by bone through a process called Cartilage is replace by bone through a process called ossificationossification

• Occurs up to 7 months before birthOccurs up to 7 months before birth• The body does not completely ossify to facilitate child birthThe body does not completely ossify to facilitate child birth

• Osteoblasts secrete minerals deposits (forming bone)Osteoblasts secrete minerals deposits (forming bone)• As the osteoblasts become surrounded by bone tissue the mature As the osteoblasts become surrounded by bone tissue the mature

into ostocytesinto ostocytes

• Growth PlatesGrowth Plates• Sites each end of the bone that contains growing cartilageSites each end of the bone that contains growing cartilage• As the cartilage gets replaced by bone we stop growingAs the cartilage gets replaced by bone we stop growing

Ball-and-Socket Joint

Hinge Joint

Pivot JointClavicle

Ball-and-socket joint

Scapula

HumerusFemur

Patella

Hinge joint

Tibia

Fibula

Humerus

Radius

Pivot joint

Ulna

Metacarpals

CarpalsSaddle joint

Saddle Joint

C. Joints

D. Major Bones

Skull

Sternum

Ribs

Vertebral column

Metatarsals

Metacarpals

Phalanges

Clavicle

Scapula

Humerus

RadiusPelvisUlnaCarpals

Femur

Patella

Fibula

TibiaTarsals

Phalanges

Appendicular Skeleton

E. MovementE. Movement

Movement occurs between the coordination Movement occurs between the coordination of the skeletal and muscular systemsof the skeletal and muscular systems

1.1. TendonsTendons• Bundles of connective tissue that link muscle to boneBundles of connective tissue that link muscle to bone• Damage is usually irreversibleDamage is usually irreversible

2.2. LigamentsLigaments• Bundles of connective tissue that link bone to boneBundles of connective tissue that link bone to bone• Common ailment is a torn ACLCommon ailment is a torn ACL