MUSCULAR SYSTEMpp. 917-920

FUNCTION

• Support, movement, and protection

TYPES

• skeletal – muscles that move bones (voluntary)

• smooth – involuntary muscles that protect organs

• cardiac – involuntary muscles found only in heart

MUSCLE STRUCTURE (external)

• Tendons connect muscle to bone

• When the muscle moves, the bones move, and the joint bends

MUSCULAR MOVEMENT

• Muscles arranged in opposing pairs and while one relaxes the other contracts

flexor: contraction bends the joint

extensor: contraction straightens the

joint

myofibril muscle cell (fiber)fascicle muscle

MUSCLE STRUCTURE (internal)

• Two types of proteins (actin and myosin) involved

• actin + myosin myofibril • myofibril attaches to Z line• sarcomere: functional unit from Z line to Z

line

MUSCLE CONTRACTION

• contraction: shortening of sarcomere between Z –lines

• myosin “heads” walk along the actin• this requires ATP to walk and to release the

myosin after walking

ENERGY and FATIGUE

• Aerobic respiration: breaking down organic compounds to release energy to be used by the body

• Fatigue is the inability to contract (and release) the muscle due to the lack of ATP

SKELETAL SYSTEM

pp 911-916

FUNCTION

• Bones supports and protects organs

• Gives shape and structure to the body

• Produce red and white blood cells

SKELETON

• Axial –the skull, face, vertebral column, and rib cage.

• Appendicular –the arms and legs, pelvis, scapula, collar bone, etc

• Includes bones and their associated tissues (cartilage and ligaments)

BONE STRUCTURE• Porous and made of proteins and minerals and

contains:

a) Osteocytes –cells that make bone

b) Bone marrow – soft bone tissue that produces platelets and blood cells

BONE DEVELOPMENT

• Bones develop from cartilage hardening (ossification)

JOINTS

• Place where two bones meet

• Fixed: no movement between bones (ex. skull).

• Semimovable: limited movement (i.e. rib cage and vertebrae)

• Movable: see your coloring

JOINT STRUCTURE

• Cartilage between joints for cushion• Ligaments connect joints