1. Muscles and Movement

2. Coordinating Movement
Movement is controlled by a variety of things working together
Bones: Support the body, facilitate movement, protect internal organs, site of blood cell formation and metabolism of calcium and other ions
Muscles: attach to bones and provide forces necessary to change the position of the bones. Many muscles occur in antagonistic pairs
Tendons: attach muscles and bones
Ligaments: attach bones to other bones
Nerves: Send and receive messages from the brain and aid in the control of movement

3. Joints
Joints are points where the bones meet and are classified according to structure and function
Structural classifications focus on materials and the presence of a joint cavity
Can be fibrous, cartilaginous or synovial
Functional classifications focus on the amount of movement allowed
Synarthroses (immovable joints)
Amphiarthroses (slightly moveable)
Diarthroses (freely moveable)
Most joints in the body are synovial

4. 5 Distinguishing Features of Synovial Joints
Articular cartilage – hyaline cartilage covers opposing bone surfaces
Joint Cavity – a potential space that contains a small amount of synovial fluid
Articular Capsule – encloses the joint cavity; strengthens the joint so it is not pulled apart
Synovial Fluid – occupies all free spaces within the joint capsule; reduces friction; uses ‘weeping lubrication’ mechanism – fluids move in and out of area with compression of joint
Reinforcing Ligaments – joint strengthened by ligaments (those that are ‘double jointed’ have more stretchy ligaments)

5. Types of Synovial Joints
Plane Joints – articular surfaces are essentially flat; allow for gliding movements (intercarpal and intertarsal joints)
Hinge Joints – a cylindrical projection of one bone fits into another a trough-shaped surface on another (elbow)***
Pivot Joints – the rounded end of one bone protrudes into a ‘sleeve’ or ring composed of bone (radius/ulna)***
Condyloid Joints – the oval articular surface of one bone fits into a complementary depression in another; both articulating surfaces are oval (wrist, knuckle and knee)***
Saddle Joints – similar to condyloid joints but allow for more freedom of movement; both bones have concave and convex areas (carpometacarpal joints of thumbs )
Ball-and-Socket Joints – the spherical or hemispherical head of one bone articulates with the cuplike socket of another (shoulder and hip)***

6. The Elbow Hinge joints limit the movement to a single plane
Humerus-Ulna
Pivot Joints limits movement to a rotation
Humerus-Radius
The movements are controlled by two antagonistic muscles: the biceps and the triceps

7. The Knee The knee is considered a complex, compound condyloid joint.
This allows for greater range of motion when the joint is flexed than when it is extended.

8. The Hip
The joint between the pelvis and the femur is considered a ball and socket joint.
This allows the leg to both flex and extend as well as rotate and move sideways and back

9. There are 3 types of muscle
Muscles
There are 3 types of muscle
Skeletal – move and support the skeleton
Cardiac – found in the heart and composes the walls of the heart
Action potentials are triggered without input from the nervous system
Smooth – found mainly in the walls of hollow organs, such as blood vessels and digestive organs

10. Muscle Function
Skeletal muscle is attached to the bone and is responsible for movement
Muscles consist of bundles of fibers where each fiber is a single cell with multiple nuclei
Running longitudinally across the fibers are myofibrils
Thin (actin and regulatory protein) and thick filaments (myosin) composed of proteins
The arrangement of fibers causes the muscle to be striated. Each repeat unit is a sarcomere, the basic contractile unit of the muscle

11. Sliding-Filament Model of Muscle Contraction
As the sarcomere shortens, neither the thin or thick filaments change in length
Filaments slide past each other, increasing the overlap of the thin and thick filaments
Based on interaction between actin and myosin
Myosin head is attached to head of ATP which it hydrolyzes to ADP, binding the myosin head to actin. This forms a cross-bridge.
When a new ATP binds to the myosin, the cross-bridge is broken. The cycle can then begin anew

12. Muscle Contraction
Calcium and regulatory proteins also play an intricate role in controlling muscle contracting and relaxation
Regulatory proteins tropomyosin and troponin complex bind to actin in thin filaments. When muscles are at rest, tropomysin covers myosin bind sites, inhibiting interaction
When calcium is present, it binds to troponin complex, causing the protein to shift position
This allows cross-bridges to form
Calcium will be removed via active transport by sarcoplasmic reticulums returning the cell to normal

13. Skeletal Systems 3 major types of skeletal systems
Hydrostatic – fluid held under pressure in a closed body compartment; muscles change the shape of the compartment
Cnidarians, flatworms, nematodes, annelids
Exoskeleton – hard encasement on the animal’s surface
Bivalves, arthropods
Endoskeleton – hard supporting elements within the soft tissue
Echinoderms, chordates