Support Systems & Locomotion

( Bones and Muscles)

By: Mr. Wolf

Types of Skeletons

*The three types of skeletons are:

Hydrostatic skeleton,

Exoskeleton,

Endoskeleton.

The Hydrostatic Skeleton

Hydrostatic skeleton- A hollow column of liquid within one of the body spaces that provides support or firmness to an organism or one of its parts.

Exoskeleton

Clam & snail exoskeleton’s grow with the animals. (Thick calcium carbonate shell is it’s protection).

The exoskeleton of arthropods is jointed and moveable. Arthropods molt when the exoskeleton becomes to small, which makes them more vulnerable to predators.

Endoskeleton*Vertebrates have an endoskeleton composed of bone and cartilage that grows with the animal.

*The endoskeleton does not limit space available for internal organs.

*It is able to support much greater weight.

*Soft tissues surround the endoskeleton to protect it; injuries to soft tissue are easier to repair.

The Skeletal System*The Skeletal System serves many important functions;

•Support/Framework: provides the shape and form for body and support for soft tissues

•Movement: allows bodily movement, joints make complex movement possible. Muscles connect to bone for movement.

•Protection: vital organs are protected by the skeletal system.

–brain is protected by the surrounding skull

–heart and lungs are encased by the sternum and rib cage.

•Blood cell formation: produces blood cells for the body (red and yellow marrow)

•Mineral reservoir: important minerals such as Ca, P, Na, K, Mg are stored in bones.

Anatomy of a “typical” bone

Cartilage (articular)

Spongy bone

Medullary canal

Compact bone

periosteum

Microscopic View of compact bone

Are your bones alive?*They absolutely are alive!

*Bones are made of cells in a matrix of substances and fibers:• Organic framework - collagen fibers that provide tensile

strength and flexibility

• Inorganic salts - to help withstand compresssion.

• Living cells - which help them grow and repair themselves. Like other cells in your body, the bone cells rely on blood to keep them alive.

*If bones weren’t made of living cells, things like broken toes or arms would never mend.

• Continual Process

• Called Ossification• Cells build, maintain,

break down, and rebuild bone continually (normally)

Bone Cell Types:

-Osteocytes: bone maintaining cells,

found in developed bone.

– Osteoclasts: absorb/break down bone

– Osteoblasts: form/rebuild bone

• Osteoclasts: break down bone and deposit calcium into blood.

– Maintain steady blood calcium level to maintain homeostasis.

• Calcium ions are vital for muscle contraction and nerve function.

• Blood Calcium Level regulates the balance of bone destruction and renewal.– Normal Level: destruction by osteoclasts repaired by

osteoblasts is equal; maintaining constant bone mass.

– Low blood calcium level: destruction by Osteoclasts greater then what is repaired by Osteoblasts, therefore decreasing bone mass slightly.

Normal vs. Osteoporosis

Shapes of BonesThere are 4 different types of shapes your bones can be classified as.

Learn your bones!!!

The Muscular System

*Muscles are bundles of cells and fibers.

*When muscles contract, they shorten. So therefore, they must work in antagonistic pairs.

-One muscle of an antagonistic pair bends the joint and brings the limb toward the body.

-The other one straightens the joint and extends the limb.

*Even at rest, muscles maintain tone by some fibers contracting; essential to posture.

The Musculo-skeletal System

*Bodily movement is carried out by the interaction of the muscular and skeletal systems. For this reason, they are often grouped together as the musculo-skeletal system. Muscles are connected to bones by tendons. Bones are connected to each other by ligaments. Where bones meet one another is typically called a joint. Muscles which cause movement of a joint are connected to two different bones and contract to pull them together. An example would be the contraction of the biceps and a relaxation of the triceps. This produces a bend at the elbow. The contraction of the triceps and relaxation of the biceps produces the effect of straightening the arm.

Types of MuscleThe three types of muscle are: Skeletal muscle, cardiac

muscle, and the smooth muscle.

Definitions of these are in your packet.