The Skeletal System Stephen Pou & Rahul Rai Human Biology 6-Wolsko

Skeletal System Overview Consists of 206 bones divided into two main categories: –Axial Skeleton –Appendicular Skeleton Has major functions Made of different types of bones Bones are about 13% of total body weight

Functions Support  keeps the body up and gives it shape and form Protection  protects organs from damage Movement  gives the body the ability to move

Functions Storage  stores minerals such as calcium and iron Blood Cell Production  makes the red blood cells Endocrine Regulation  regulates fat and blood sugar deposition

Axial Skeleton Made up of the vertebral column, thoracic cage, and skull Has 80 bones in total Transmits weight of upper body to lower body.

Appendicular Skeleton Has a total of 126 bones Consists of the upper and lower extremities and the pelvic and pectoral girdles Distributes weight from head and torso evenly throughout body

Types of Bones Long: –Used to support body weight –Composed of mostly compact bone with little marrow –Found in the legs and arms Short: –Thin layer of compact bone with mostly marrow –Found in wrists and ankles Flat: –Two thin layers of compacts bone with marrow in the middle –Found in skull and sternum

Types of Bones Irregular: –Don’t have a specific shape –Usually have even amount of marrow and compact bone –Found in hips and spine Sesamoid: –The bones embedded in tendons –Increases leverage of muscle –Found in wrists and ankles

Bone Composition Made up of two types of material: –Compact/dense bone Forms the outside of bone Very strong Formed by stacked layers of tissue –Spongy bone Inside of bone known as the marrow Light and porous Absorb stress from compact bone

Bone Cartilage Cartilage is the connective tissue between bones There are 3 different types: –Firbro  strongest type of cartilage found in high stress areas –Hyaline  strong but flexible cartilage that reduces friction and eases bone movement –Elastic  not very strong but really flexible; provide flexibility in low stress areas dkvskf vnd

Tendons, Ligaments & Joints All three are connections of bones and are made of hyaline cartilage Keep bones together and provide movement and flexibility

Tendons, Ligaments & Joints Tendons –Connects bone to muscle –Provides the expand and contract that the muscle does in order to move Ligaments –Connects bone to bone –controls range of motion and stabilization in the joints Joints –Formally known as an articulation –With the help of ligaments, give bone connections movements and range of motion

Tendons, Ligaments & Joints There are different types of joints that are used for different purposes and classified by their type of movement: –Ball and socket –Hinge –Condyloid- a joint that provides angular motion –Pivot –Gliding (Plane) –Saddle

Ossification Ossification- the process in which bones are made –This is done by connective tissue turning into bone or bone-like material –Done by two different processes: Endochondral Ossification Intramembranous Ossification –The difference between these two processes are that endochondral is when your body matures and intramembranous is when a human is being formed inside of a whom.

Ossification Endochondral Ossification  gradual transformation of cartilage into bone –Happens as osteoblasts turn into osteocytes which are a hardened, mature form of osteoblasts

Ossification Intramembranous Ossification  the development of embryonic cells into bone –The embryonic cells involved develop into connective tissue then blood and bones

Osteoporosis  When, for a variety of reasons, a person’s Bone Mineral Density (BMD) decreases and is below the normal amount Reasons for Osteoporosis –Age –Lack of calcium –Low estrogen levels Some symptoms include severe back pain, height loss, frequent bone fracture Cures include: –Calcium pills –Menopausal hormone therapy –Prescribed medication

Osteoarthritis  The breakdown of cartilage in joints causing inflammation Causes include: –Heredity –Obesity –Injury to a joint –Overuse of a joint Symptoms are soreness and aching, inflammation, bony enlargements on joint To cure Osteoarthritis: –Exercise –Avoid use of joint (crutches, wheelchair, bandage) –Temperature treatments –Prescribed medication

Rheumatoid Arthritis  Chronic arthritis usually affecting both sides of the body (ex. Both wrists or both ankles) A person could get RA genetically, by being obese, suffering an injury, or overuse of a joint A person could get RA genetically, by being obese, suffering an injury, or overuse of a joint Symptoms include: Symptoms include: –Joint pain –Swelling –Fatigue Methods to totally cure RA do not exist but one could take could take Disease-Modifying Anti- Rheumatic Drugs (DMARDs) to slow down the progression of RA