DAY 3Muscular System / Skeletal System

Presented by : Franz Christian D. Irorita, 2012

SKELETAL SYSTEM

Functions Types Formation Names of Bones

What is the Skeletal System for?

Blood Production Mobility Structure Support

What are the types of Skeletons? Hydrostatic, Exoskeletons,

Endoskeletons

Hydrostatic Skeletons

Something like a balloon filled with water.

Fluid is held under pressure.

Contracting muscles push against the tube of the fluid, causing change in shape and movement of body.

Delicate movements are almost impossible because the force exerted by the contracting muscles is transmitted equally in all directions.

Exoskeleton

A lifeless deposit atop the animal. Inhibits growth. Made of chitin. Requires the animal to molt, which

leaves the animal vulnerable to predators

Endoskeletons

Promotes growth Living Axial and Appendicular Easy Mobility Continually grows

The Axial Skeleton

Located at the central axis of the body

Skull, Rib cage, Vertebrae, Sternum SUPPORT PROTECTION

The Axial Skeleton

Skull

Rib Cage

Vertebrae

Sternum

The Appendicular Skeleton

Located at the limbs Long Bones, Digits, Girdles MOBILITY

The Appendicular Skeleton

Clavicle&Scapula Humerus Radius&Ulna Pelvic Girdle Carpals,Metacarpals Femur Tibia&Fibula Phalanges Tarsals,Metatarsals

Long Bones

Radius, Ulna, Humerus, Femur, Tibia, Fibula

Compact & Spongy

Formation of Bones : Ossification Osteoblasts secrete collagen,

forming fibers for the bone. Osteoclasts secrete enzymes that

digests bone, so that Osteoblasts can remodel the bone as needed.

Intramembranous development The next time you see a newborn, try

touching her forehead.

It is such because the flat of the skull is developed from a noncartilage, connective scaffold, “cartilage islands”.

Joints

Functional Immovable Slightly-movable Freely-movable

Structural: Fibrous Cartilaginous Sinovial

Muscular System

Actin Myosin

Muscle cells

Functions of the Muscular System:

•Movement•Support•Thermogenesis

Three Types of MusclesSkeletal Smooth Cardiac

Location Attached to Skeleton

Walls of stomach, intestines, etc.

Walls of the heart

Type of Control Voluntary Involuntary Involuntary

Shape of Fibers Elongated, Cylindrical, Blunt ends

Elongated, Spindle shaped, Pointed ends

Elongated, Cylindrical fibers that branch and fuse

Striations Present Absent Present

Number of Nuclei per fiber

Many One One or Two

Position of Nuclei

Peripheral Central Central

Speed of Contraction

Most Rapid Slowest Intermediate, varies

Ability to remain contracted

Least Greatest Intermediate

Muscles may contain thousands of muscle fibers Muscle fibers are elongated cells that

are organized in bundles called fascicles.

Ex. The biceps in your arms consists of thousands of individual muscle fibers.

Muscle Fiber Structure

Cytoplasm of Muscle Fiber = Sarcoplasm Endoplasmic Reticulum = Sarcoplasmic

Reticulum Myofibrils = threadlike structures

running lengthwise through the muscle fiber, composed of even smaller structures called myofilaments.

Sarcomeres = basic unit of muscle contraction, consisting of overlapping myosin and actin filaments.

Muscle Contraction occurs when actin and myosin filaments slide past each other The sliding filament Theory.

The Sliding Filament Theory

Skeletal Muscles work antagonistically Example : Biceps and Triceps Agonist & Antagonist

Muscles respond in specific ways Smooth muscle contracts in response

to simple stretching, its contraction can be sustained.

Cardiac muscle alternately contracts and relaxes in rhythm, propelling blood with each contraction.

Skeletal muscle is stimulated by a brief electrical stimulus, responding with a simple twitch.

Tetanus

A single, smooth, sustained contraction of the muscle.

White and Red Fibers

White = fast response Red = slow, enduring activities

Example : Chicken’s legs have red fibers while its breast have white fibers.

Fast-twitch vs. Slow-twitch Fast-twitch = moderate, enduring

activities Slow-twitch = long, slow response

Questions?