Organization

• Cell (ex=muscle cell) • Tissues (many of the same types of cells ex

muscle tissue)• Organ (many tissues that work together ex

heart)• Organ system level (many organs work

together ex circulatory system)• Organism level (many organ systems work

together)

Bones and ligaments

Bone Structure

• Compact bone – hard outer surface

• Spongy bone – Swiss cheese like matrix interior. To cushion impact.

• Bone marrow – source of red and white blood cells

• Haversian Canals – blood vessel canals through compact bone

osteoporosis

• Disease of the bone, causes of which are largely unknown.– Mineral deficiencies promote

disease, especially Calcium.– Decrease in bone density– Predominantly older women– Prevention – Get plenty of

Calcium at a young age, exercise helps build bone strength

Joints – 4 types

• Ball and socket – all directions– Shoulder and hips

• Pivot joints – twist around– Arm, vertebrae

• Hinge joints – lever or hinge action– knees, fingers, toes

• Gliding – slide past one another– Wrist, ankle

Ligaments

• TOUGH connective tissue that links bones to bones

Ligaments

• Connect bone to bone (joints)

Tendons

• Collagen connective tissue that links bone to muscle. When muscle contracts, pulls on tendon, moves bone.

Muscles and Muscular Contraction

3 types of muscle cells

• Smooth muscle – internal organ walls, blood vessels (enables dilation and contraction)– Sheets of cells, all

acting in concert– Many work together to

squeeze– Involuntary muscle

• Cardiac Muscle– Only found in heart– Striated– Involuntary– group of cells contract

together

• Skeletal Muscle•Voluntary muscle• Multinucleated•Striated•The muscles in your arms, legs, etc.

Skeletal cont…

• Structure:

MuscleFasicleMyofiber (cell) Myofibril (with

many sarcomeres)Myofilaments

• Many myofibers connected lengthwise through entire fiber

• Many mitochondria• Many nuclei (why? The multiple

nuclei arise from the fact that each muscle fiber develops from the fusion of many cells (called myoblasts).

Skeletal cont…

• Sarcomere (small part of myofibril)– Made up of thin

(Actin) and thick (Myosin) filaments

– Thin slide across thick

Contraction – Sliding Filament Theory

• When muscle contracts its shortens. When muscle relaxes it DOES NOT lengthen beyond relaxed state

• Actin and Myosin slide across one another (they do not shorten or lengthen)

• Myosin head binds actin and pulls it, causing sliding. Requires help of Calcium and _______.ATP

Actin/Myosin animation