1. Skeletal, Muscular & Integumentary Systems

2. 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
An adult has 206 bones in their body

3. Skeletal System Divisions
Axial – supports the central axis of the body (skull, vertebral column, rib cage
Appendicular – bones of the arms, legs, pelvis & shoulder

4. 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
At birth, most bone marrow is red. Adults have about 50% yellow marrow. About 8 million rbc’s are created every second. Yellow marrow is mostly fat, and as we age, it can be found in places where red marrow once resided -- some of the bones in our arms, legs, fingers and toes, for instance. If the body needs more blood cells, yellow marrow can transform back into red marrow and produce them. Some bones have a lot more red marrow than others -- the pelvic bone, the spine's vertebrae and our ribs are all rich with it. The body also stores iron in bone marrow.
Innermost layer = bone marrow
Yellow marrow – mostly fat cells
Red marrow – produces rbc, some wbc, platelets, contains stem cells

5. 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

6. 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
Bones connect to bones with tough connective tissue called ligaments. Joints are enclosed in sacs called bursa filled with liquid (synovial fluid) to allow smooth movement.

8. 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

9. 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

10. Smooth Muscle Spindle –shaped cells One nucleus
Found in walls of hollow structures (blood vessels, stomach, intestines)
Involuntary control

11. Cardiac Muscle Striated Has one or two nuclei per cell
Usually involuntary control
Found ONLY in the heart

12. 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

13. (Click)

14. 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.
A strong muscle contraction is the result of MANY muscle fibers contracting. The greater the number of muscle fibers activated, the stronger the muscle contraction.

15. 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.

16. 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

17. Skin Anatomy Epidermis Dermis Hypodermis 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
Skin cancer can be caused by excessive exposure to UV radiation from the sun.
Hypodermis
Mainly fat storage
Contains larger blood vessels & larger nerve fibers

18. 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

19. Nails grow from an area of rapidly dividing cells = nail root.
Nails grow at an average of 3mm per month (fingernails grow more rapidly than toenails)