The Integumentary, Skeletal, &
Largest organ in the body
Part of integumentary system
Integumentary includes skin, hair, nails, and
number of important glands in skin.
Skin has three layers
1. Outer layer - Epidermis
2. Inner Layer -Dermis
3. Lowest Layer - Hypodermis
Supports the Epidermis
Contains important cells for:
The body’s Sweat/Oil Glands are
located here also
Produces cells that are pushed toward
the surface. Produces keratin as they
Keratin – Tough, flexible protein
◦ Major protein found in fingernails
◦ Forms a tough waterproof layer on top of
•Hair is produced from columns of cells that
are filled with keratin and then…. DIE.
•Clusters of cells make up Hair Follicles.
•Toenails/fingernails are formed by keratin-
forming cells for a flattened plate.
All vertebrates have an internal skeletal
Bones store supplies of calcium and
Internal Skeletal System
◦ Provides support for the upper body
◦ Attachment sites for muscles
◦ Protects internal organs
Periosteum- tough layer surrounding
Inside the periosteum is a dense layer of
Spongy bone is found inside the compact
Osteocytes- Cells found in C & S bone.
◦ Help build and maintain bones
Bones are produced by Cartilage.
Cartilage is produced at growth plates &
gradually is replaced by bone as the
A place where two bones meet.
3 kinds of joints:
Little or no movement between bones
Mostly located in the skull
◦ Slightly Moveable
Small amount of movement
Mostly located in a Spinal Column or Ribs
◦ Freely Moveable
Wide Range of movement
Ex: Shoulders and hips
Joints are enclosed by a Joint Capsule.
Inside the capsule is Synovial Fluid
◦ Natural lubricant that reduces friction &
allows the cartilage coated bones slip past
each other easily
There are 3 types of muscle tissue:
Each of these three types muscle, have a
different cellular structure.
Skeletal Muscle Tissue
Generally attached to the bones of the
skeleton and is usually under voluntary
Skeletal muscle tissue is behind every
conscious movement you make
◦ Ex: Lifting a weight
This is because most skeletal muscle tissue is
controlled directly by the nervous system.
Cardiac Muscle Tissue
Cardiac muscle tissue is found in just one
place : The Heart
Cardiac muscle tissue is striated, but the
smaller Cardiac muscle cell have just one
nucleus, and they are not under the direct
control of the Central Nervous
Smooth Muscle Tissue
Smooth muscle tissue is found in the walls
of many internal organs, except the heart.
The cells of the smooth muscle tissue are
spindle shaped, have a single nucleus, and
are not striated.
Not always under the conscious control
of the nervous system.
Responsible for actions not under
Myosin- Thick filaments that are made of
Actin- Thin filaments that are made up of
Sliding Filament Theory
When hundreds of thousands of actin-
myosin cross-bridges go through their
cycle in a fraction of a second, the muscle
cell contracts with siderable force.
To make well-coordinated movement,
muscle contractions must be carefully
A single motor neuron may form synapse to
one or several muscle cells. An impulse in
the motor neuron causes the release of a
◦ This causes a new action potential. In turn causes
the release of calcium ions into the cytoplasm of
When calcium flows into the cytoplasm, cross-bridges
form, and the muscle contracts.
Muscles and Movements
Muscles produce force by contracting.
Attached to bones by tendons, a muscle
can pull two bones together, using the
joint between them as a lever.
An individual muscle can pull by
contracting, but cannot push.
◦ If that’s true, then how can you push a door
open or do a pushup?
The answer is that skeletal muscles are arranged in
pairs. These pairs oppose each other and produce
forceful movements in either direction.
Specialized Skeletal Muscle Fibers
Skeletal muscles contain two main types
of muscle fibers
Whose properties make them specialists at
different kids of exercise.
Red Muscle Fibers
Contain large amounts of reddish oxygen-
storing protein myoglobin.
Red fibers have rich blood supplies and
plenty of mitochondria to produce ATP.
White Muscle Fibers
Called fast- twitch muscle fibers and can
generate powerful contractions.
The contain few mitochondria , these
fibers contain greater densities of
contractile proteins than red fibers do.
◦ The powerful fibers fatigue easily, however,
which means that they can produce maximum
contractions for only a few seconds at a time.
Exercise Muscle Cells
Aerobic exercises, such as running,
swimming, and bicycling cause your body
system to become more efficient.
◦ Resistance exercise, such as weight lifting,
increase muscle size.