unit 33 musculoskeletal system

33.1 Skeletal System

KEY CONCEPT The skeletal system includes bones and tissues that are important for supporting, protecting, and moving your body.


Your skeletal system is made up of the appendicular and axial skeletons.

• The skeletal system protects, supports, and moves the body.


• The appendicular skeleton includes legs, arms, feet and hands. – allows for movement– includes bones called girdles that connect limbs to

body


• The axial skeleton includes the skull, rib cage, and spinal column.

skull

rib

breastbone

vertebra

– supports body and protects tissues

– allows for limited movement


– cushions bones – allows for smooth movement– connect two bones

• Cartilage is connective tissue between bones.

cartilage


Bones connect to form joints.

• Joints are places were two bones meet.• There are three types of joints.

– fibrous, which does notallow for movement

fibrous joint




cartillage

– cartilaginous, which allows partial movement



– synovial, which allows for greater movement



• Ligaments are long bands of tissue that connect bones across a joint.

ligament


• There are several types of synovial joints.– gliding– pivot– ball-and-socket– saddle– hinge

GLIDING JOINT

PIVOT JOINT

BALL-AND-SOCKET JOINT

SADDLE JOINT

HINGE JOINT


Bones are living tissue.

• Bone is made of compact bone tissue and spongy bone tissue.

Compact bone

Spongy bone


• Compact bone is hard and dense.– Osteocytes (bone cells) maintain compact bone rings.– Haversian canals allow blood vessels in the bone.

osteocytes blood vessel

Haversian canals


• Spongy bone protects red or yellow bone marrow.– Red bone marrow produces blood cells.– Yellow bone marrow is mostly fat.

PeriosteumA layer of connectivetissue that covers bone

Red bone marrow


• Calcification is the process of building hard bone.– combines collagen and calcium phosphate– transforms cartilage into hard bone during childhood

osteocyte

compact bone


KEY CONCEPT Muscles are tissues that can contract, enabling movement.


Humans have three types of muscle.

• The muscular system moves substances throughout the body.– bones of the skeletal system– food through digestive system– blood through circulatory system– fluids through excretory system


– skeletal muscle

• There are three types of muscle tissue.

SKELETAL MUSCLE CARDIAC MUSCLESMOOTH MUSCLE

– smooth muscle– cardiac muscle


• Skeletal muscle attaches to the skeleton by tendons.– Tendons connect muscle to bone.– Skeletal muscles are mostly voluntary.

SKELETAL MUSCLE


– move food through digestive organs– empty liquid from the bladder– control width of blood vessels

• Smooth muscle lines organs and is involuntary.

Smooth musclearound this artery allows theartery to regulate blood flowby shrinking and expanding.

SMOOTH MUSCLE


– pumps blood throughout body– controlled by pacemaker– contains more mitochondria than skeletal muscle cells

• Cardiac muscle is found only in the heart.

CARDIAC MUSCLE


muscle fiber

Muscles contract when the nervous systems causes muscle filaments to move.

• Muscle fibers are cells of the muscular system.

muscle


• Myofibrils are long strands of protein in the muscle fiber.

muscle fibermuscle

myofibril


• Each myofibril is divided into sarcomeres.• Sarcomeres contain filaments that cause contraction.

myofibril

muscle fiber

muscle

sarcomere


• Each myofibril is divided into sarcomeres.• Sarcomeres contain filaments that cause contraction.

– Actin filaments are pulled during contraction.– Myosin filaments pull actin during contraction.

CONTRACTION

RELAXATION

M linemyosin

Z line


• Neuron stimulates muscle at the neuromuscular junction.

neuromuscular junction

neuron

MUSCLE


• Neuron stimulates muscle at the neuromuscular junction. – Neurotransmitters

cause calcium channels in the sarcomere to open.

regulatory protein

– Calcium exposes binding sites.

– Myosin binds to actin and pulls it.

– As the sarcomere shortens, the muscle contracts. myosin

actin

Z line


KEY CONCEPT The integumentary system has many tissues that protect the body.


The integumentary system helps maintain homeostasis.

• The integument is the body system that surrounds all your other organ systems.


The integumentary system helps maintain homeostasis.

• The integumentary system consists of many parts.– skin– hair– nails– oil glands– sweat glands– proteins,

such as keratin


• Integumentary system removes substances from the body.– water– salts– urea

pore

sweatglands


• The outermost layer of the skin is the epidermis.– dead skin cells– oils– pores

The integumentary system consists of many different tissues.

epidermis

pore


– Keratin makes cells waterproof and tough feeling.

• Cells in the epidermis produce keratin and melanin.

– Melanin is a dark pigment that absorbs UV rays.


– sweat glands– oil glands– pressure receptors– blood vessels– hair follicles

• The dermis contains most of the tissues in the skin.

dermis

hair follicle

oil gland

pressurereceptors

sweat gland


• The dermis also produces elastin and collagen.

• A hair follicle is pit of cells that produces hair.

– Elastin makes skin flexible.– Collagen gives skin its shape.


• Beneath the dermis is a layer of fat.

fat layer

unit 33 musculoskeletal system

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