HUMAN BODY Climbing the walls? Spiderman is able to climb walls

The explanation: 1.Hairs (called setae) on gecko’s toes contain split ends (called spatulae) 2. ability to “stick” to surfaces from attractions between molecules on the spatulae and the surface on which the gecko is crawling

Artificial tissues have medical uses: c an assist in the healing of several injuries

SKELETON human skeleton: 206 bones –axial skeleton: Skull Backbone rib cage –appendicular skeleton: bones of the arms and legs and the joints where they attach to the axial skeleton –pectoral or shoulder joint –pelvic or hip joint

–Movable joints Provide the human skeleton with flexibility

Bones are complex living organs: –Cartilage at the ends of bones: Cushions the joints - Bone cells, serviced by blood vessels and nerves Live in a matrix of flexible protein fibers and hard calcium salts –Long bones have a central cavity: to store yellow bone marrow, which is mostly stored fat –Spongy bone contains red marrow: blood cells are made

Broken bones can heal themselves: re realigned and immobilized

–Artificial joints: often used to repair severe injuries

Weak, brittle bones are a serious health problem, even in young people Osteoporosis, a bone disease characterized by weak, porous bones

dynamic bone “remodeling” model: going on all the time: –osteoblasts deposit bone –osteoclasts break bone and release calcium –As a person ages, the backbone and other bones tend to decline in mass; excessive bone loss is called osteoporosis

The skeleton and muscles interact in movement:

MUSCLES Muscle cells are the motors of the body contractible proteins fibers, myofilaments with the proteins actin and myosin

Muscle Fascicle Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Levels of Functional Organization in a Skeletal Muscle Fiber Muscle Fiber Myofibril Sacromere

3 types: Smooth muscle: walls of blood vessels and the gut Skeletal muscle: move the bones of the skeleton Cardiac muscle: fibers that branch and interconnect to form a network connected, electrical impulses passes from cell to cell causing the heart to contract in an orderly fashion

Skeletal muscles move the bones Tendons: connective tissue that attach muscles to bone Muscle tone: Even at rest, some of the motor units of muscles are always contracting= resting tension

Athletic training increases strength and endurance: causes increases in: - number of mitochondria - concentration of glycolytic enzymes - glycogen reserves - myofibrils

Types of sports fast or white fibers: Large in diameter-densely packed myofibrils Large glycogen reserves few mitochondria Can contract in 0.01 sec following stimulation uses a lot of ATP uses anerobic glycolysis: converts stored glycogen to lactic acid fatigue rapidly because glycogen reserves are limited and lactic acid builds up Slow or red fibers: Only 1/2 the diameter of fast fibers Takes 3 times longer to contract after stimulation abundant mitochondria Uses aerobic metabolism Has a more extensive capillary network Red color due to red pigment of myoglobin

Muscles only pull because myofibrils contract: –muscles in the joints are attached in opposing pairs called flexors and extensors –when contracted they move the bones in different directions

sliding filament model: muscular contraction –the head of a myosin filament binds to an actin filament –ATP is used to flex the myosin head –when the muscle contracts, the myosin head returns to its original shape and pulls the actin it is attached to along with it