Transcript Bio Skeletal Muscular Integumentary Systems 2013

Skeletal, Muscular &
Integumentary Systems
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Skeletal System
FUNCTIONS:
 Supports the body
 Protects internal organs
 Provides for movement
– levers act with muscles
 Stores mineral reserves
 Provides a site for
blood formation
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Skeletal System Divisions
Axial – supports the central
axis of the body (skull,
vertebral column, rib cage
Appendicular – bones of
the arms, legs, pelvis &
shoulder
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Bone Structure
Bones are living tissue –
a solid network of cells &
protein fibers that are
surrounded by hardened
deposits of calcium salts
Outer layer = periosteum
(tough connective tissue)
Thick inner layer =
compact bone with
Haversian canals
Second inner layer =
spongy bone
Innermost layer = bone marrow
• Yellow marrow – mostly fat cells
• Red marrow – produces rbc, some wbc,
platelets, contains stem cells
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Bone Development
An embryo skeleton is almost entirely
cartilage
 Strong, flexible connective tissue
 No blood vessels
Cartilage is replaced by bone during the
process of ossification
Ossification
begins 6-7 months
before birth
Bone growth occurs
at the ends of long bones
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Bone Connections
Joint – place where one bone connects to another bone
Bones connect to bones through ligaments
Joint Types:
Immovable joint (fixed joints) – allow no movement
between bones that touch each other (skull)
Slightly movable joint – small amount of restricted
movement (slight separation from each other)
(vertebrae)
Freely movable joint – permit movement
- ball-and-socket
- hinge
- saddle
- pivot
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Muscular System
Muscles are specialized tissue that can contract and
relax.
Muscles work with the skeletal
system to allow movement.
Three types of muscles:
 Skeletal – attached to bones
to allow voluntary movement
 Smooth – usually not under voluntary control
 Cardiac – heart muscle
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Skeletal Muscle
Alternating light &
dark bands (striation)
Usually voluntary
control
Large cells that can
have many nuclei
Found all over the
body – usually
attached to bones
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Smooth Muscle
Spindle –shaped cells
One nucleus
Found in walls of hollow
structures (blood vessels,
stomach, intestines)
Involuntary control
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Cardiac Muscle
Striated
Has one or two nuclei per
cell
Usually involuntary control
Found ONLY in the heart
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Skeletal Muscle Anatomy
Skeletal muscle consists of
bundles of muscle fibers
Bundles of muscle fibers are
composed of individual muscle
fiber cells
Each muscle fiber consists of
myofibrils that have light & dark
bands (striations)
Each myofibril is made up of
thick filaments (myosin protein)
& thin filaments (actin protein)
A unit of alternating actin &
myosin = sarcomere, separated
by a dense “Z band” matter
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(Click)
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Muscle Contraction Control
The axon terminal contains
vesicles with the
neurotransmitter
Acetylcholine (Ach).
An action potential causes
the vesicles to release the
Ach across the
neuromuscular synapse.
This causes the release
of Ca+ in the muscle fiber
causing actin & myosin
to interact.
As long as Ach is released, the
muscle will contract.
As soon as the Ach is stopped, the muscle relaxes.
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Muscles and bones
Skeletal muscles
connect to bones
through tendons.
There are usually
several tendons
connecting many
muscles around a joint.
Muscles usually act in
opposing pairs.
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Integumentary System
Integument = “covering”




Skin
Hair
Nails
Some glands (found in skin)
Skin primary functions:
 Barrier against infection & injury
 Helps regulate body temperature
 Removes waste products
 Protection against UV radiation
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Skin Anatomy
Epidermis
- Two layers: dead
outermost layer & inner living
layer
- Keratin
- Melanin
- No blood vessels
Dermis
- Next inner layer
- Collagen
- Many blood vessels
- Nerve endings
- Sensory receptors
- Glands: sweat &
sebaceous
- Smooth muscles
- Hair follicles
Hypodermis
-
Mainly fat storage
Contains larger blood
vessels & larger nerve
fibers
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Hair & Nails
Formed from keratin (fibrous protein)
Forms horns, reptile scales, bird feathers, porcupine
quills
Hair is produced at
the base by hair
follicles
Sebaceous (oil)
glands help
maintain hair health
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Nails grow from an area of rapidly dividing cells = nail
root.
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