1. HUMAN BODY SYSTEMS Part 1: Integumentary, Muscles, and Skeletal Systems

2. 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.

3. 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

4. Skin Contains 3 layers:

5. 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

6. 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.

7. 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.

8. 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

9. Nails Covers and protects the tips of fingers and toes Made of KERATIN – A tough, fibrous protein

10. 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.

11. Types of Muscles Cardiac Skeletal Smooth

12. Cardiac Muscle Found only in the heart Striated One nucleus

13. Skeletal Muscle Responsible for voluntary movements Striated Many nuclei

14. Smooth Muscle Responsible for involuntary movements Not Striated One nucleus

15. How do Skeletal Muscles Work? Muscles contract when thin filaments (ACTIN) slides over thick filaments (MYOSIN)

16. 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.

17. Why is it important? Supports the body Protects internal organs Stores mineral reserves Provides a site for blood cell formation

18. Two Parts AXIAL SKELETON Skull Ribs Vertebral Column APPENDICULAR SKELETON Arms Shoulder Legs Pelvis (Hip)

19. 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.

20. 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

21. Structure of Bones Spongy Bone: – Inner layer of bone – Resembles a sponge, but adds strength to a bone without adding mass

22. 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