HUMAN BODY SYSTEMS

Part 1: Integumentary, Muscles, and Skeletal Systems

Fun Facts about… the Integumentary System

• It contains your body’s largest organ… your skin.

• An average adult's skin spans 21 square feet, weighs nine pounds, and contains more than 11 miles of blood vessels.

• The skin releases as much as three gallons of sweat a day in hot weather

• In a lifetime, the average person sheds enough skin cells to fill an entire 2 story house. In one minute, you can lose between 30,000 and 40,000 skin cells.

Why is it important?• Serves as a barrier against

infection and injury

• Helps regulate body temperature

• Removes waste products from the body

• Provides protection against UV rays

• Contains sensory receptors

Skin

Contains 3 layers:

Epidermis

• The outermost layer of skin– Contains two layers of cells• The outermost layer is made of dead cells• The innermost layer of cells undergo rapid cell division

• Contains melanocytes which produce MELANIN– A dark pigment that is responsible for skin color– Helps protect the skin from damage by absorbing

UV rays from the sun

Dermis• The middle layer of skin

• Contains: blood vessels, nerve endings, sweat glands, sensory receptors, hair follicles, and smooth muscles

• Responsible for interacting with other body systems to maintain homeostasis by regulating body temperature.

Hypodermis

• The innermost layer of skin

• The storage site of most body fat

• Fastens the skin to underlying tissues and organs, insulates the body, and absorbs shocks from impacts to the skin.

Hair

• On the scalp, it protects from UV rays and provides insulation

• In the nostrils, ear canals, and around the eyes, it prevents dirt and other particles from entering the body

Nails

• Covers and protects the tips of fingers and toes

• Made of KERATIN– A tough, fibrous protein

Fun facts about… the Muscular System

• The busiest muscles in your body are the eye muscles, which approximately move more than 100,000 times in a day

• Muscles cannot push, they can only pull.

• There are approximately 640 muscles in the body.– The largest is your gluteus maximus.– The smallest are in your middle ear.

Types of Muscles

• Cardiac

• Skeletal

• Smooth

Cardiac Muscle

• Found only in the heart

• Striated

• One nucleus

Skeletal Muscle

• Responsible for voluntary movements

• Striated

• Many nuclei

Smooth Muscle

• Responsible for involuntary movements

• Not Striated

• One nucleus

How do Skeletal Muscles Work?

• Muscles contract when thin filaments (ACTIN) slides over thick filaments (MYOSIN)

Fun Facts about…the Skeletal System

• A baby is born with 300 bones, but an adult only has 206.

• 54 of those bones are in your hands.

• Humans and giraffes have the same number of bones, but giraffes’ vertebras are much longer.

Why is it important?• Supports the body

• Protects internal organs

• Stores mineral reserves

• Provides a site for blood cell formation

Two PartsAXIAL SKELETON• Skull• Ribs• Vertebral Column

APPENDICULAR SKELETON• Arms• Shoulder• Legs• Pelvis (Hip)

Structure of Bones

• Periosteum: – Outermost layer of bone

– Made of connective tissue

– Blood vessels pass through the periosteum to deliver oxygen and nutrients to the bone.

Structure of Bones• Compact Bone: – Middle layer of bone

– Dense layer that protects the bone from breaking

– Contains tubes that contain blood vessels and nerves

Structure of Bones• Spongy Bone: – Inner layer of bone

– Resembles a sponge, but adds strength to a bone without adding mass

Structure of Bones• Bone Cavity:– Contains BONE

MARROW

• Yellow Marrow: mainly fat cells

• Red Marrow: produces red blood cells, some kinds of white blood cells, and platelets