The Human Body Systems The Skeletal System

The Skeletal System Made up of 206 bones Anchors the body for movements, provides shape and support, and protects internal structures. Also, produces blood cells and stores minerals.

The Skeleton Axial skeleton: central part; forms axis. Provides support and protection Skull (cranium): protect the brain Spinal column (vertebrae): allow flexibility Rib cage: protect heart and lungs

The Skeleton Appendicular skeleton: the appendages Allows movement Upper: shoulders, arms, wrist Lower: hips, legs, ankles

Types of Joints Immovable – locks bones together like a puzzle (example: skull).

Types of Joints Slightly movable – can flex or move slightly (example: ribs).

Types of Joints Freely movable – can bend and move; ligaments hold the bones together at these joints.

Types of Freely Movable Joints Hinge joint – knees and elbows; open at angles like a door Pivot joint – elbows; rotating movement like turning a doorknob.

Types of Freely Movable Joints Ball-and-socket joint – hips and shoulders; able to make circular movements. Gliding – vertebrae, wrists, ankles; slight movements are allowed.

Types of Bones Long bones – arms and legs Short bones – fingers and toes Irregular bones – wrists and ankles Flat bones – hips and shoulders

Bone Tissue Compact bone: the outer layer of the bone; has a top layer called the periosteum which is very hard and tough. Spongy bone: inside the outer layer; less dense; strong but lightweight

Bone Tissue

Marrow and Blood Cells Inside the spongy bone is marrow, the part that produces red blood cells. Yellow bone marrow stores fat. Blood vessels carry these new cells to the rest of the body.

The Skeleton Changes Infancy – born with spaces between the pieces of our skull; as we grow, they come together. Most of your cartilage is replaced with bone. Childhood – bone growth occurs at growth plates, which determines the length and shape of the bone. Adolescence – at the end of this period, bone growth stops. Adulthood – old bone breaks down and new bone forms; when new bone forms more slowly, it can cause a decrease in bone density and bones can break more easily.

Healthy Bones Balanced diet with calcium and phosphorus and regular exercise. As you age, bones lose some minerals. This can lead to osteoporosis, a condition in which bones become weak and break more easily.

The Human Body Systems Specific Bones

Your Core The spine makes up your backbone and is called your vertebrae. There are 26 of these in total. They let you twist and bend, and hold your body upright. Your rib cage consists of usually 12 pairs of ribs that are attached to your spine. The first 7 pairs also attach in the front to a bone called a sternum.

Your Core

Your Legs At the base of your legs is your pelvis, which supports the spine and is made up mostly of your hip bones. The large bones coming from your pelvis to your knee are your femurs. Longest bone in the body.

Your Legs A fancy word for your knee is the patella. This connects your femur to two smaller bones that make up your lower leg: the tibia and fibula.

Your Legs These two bones connect to your ankle (sometimes called the tarsals), which connects it to the largest bone in your foot – the talus. There are 52 bones in your feet and ankles combined!

Your Arms The shoulder blade is called your scapula, and it is shaped like a triangle. The upper arm bone, called the humerus, is connected to your scapula and your elbow.

Your Arms On the other side of your elbow are two smaller arm bones, called the radius and the ulna. These two bones lead to the wrist, which is made up of 8 smaller bones. (carpals) Fingers and toes: Phallanges

Other bones Clavicle: collarbone; connects the shoulder to the body. Skull/Cranium: head Mandible: the lower jaw bone.

The Human Body Systems The Muscular System

The Muscular System Made up of your muscles. Allows movement, maintains body temp, and maintains posture.

Types of Muscles Skeletal: appear striped because they have light and dark fibers making them up. Sometimes called Voluntary muscles: you control when and how they move. Short-twitch muscles – allow slower movements; Long-twitch muscles – allow quick movements. The skeletal muscles work with your bones to create the musculoskeletal system. Tendons attach muscles to bones.

Types of Muscles Smooth: found in organs; move very slowly; shorter fibers than skeletal. Involuntary: you cannot control them. Stomach, intestines, etc.

Types of Muscles Cardiac: moves without control; contracts slowly unless your body is telling it to move more quickly. Cells are branched in shape; form layers that allow the heart to contract and expand easily.

Movement Muscles are made up of fibers that contract and expand, causing movement. Normally they work in pairs – when one muscles contracts, the other muscle expands. Muscles are connected to the bones by tendons.

Body Temperature When muscles contract, they release heat. When you are cold, you might shiver – the quick muscle movements produce small amounts of heat. This is also why you may get warmer while exercising.

Posture Tension, or muscle tone, can be found in some muscles all the time, which helps you stand up straight without thinking about it. Your muscles make automatic adjustments to allow you to stand upright.

How Movement Works When your muscle contracts, it pulls on the tendon, which then pulls on the bone it is connected to. Most skeletal muscles are attached to a tendon that connects it to a bone on the other side of a joint; this allows for even more movement.

Healthy Muscles Regular exercise adds strength and flexibility to muscles. A strain can occur if muscles are overworked or overstretched.

The Human Body Systems Major Muscles

Important Muscles Deltoid: move your shoulders Pectoralis/pectorals: upper chest muscles Abdominals: the muscles beneath your rib cage. Obliques: the muscles on the sides of your stomach

Important Muscles Bicep: the muscle seen when you flex your upper arm. Tricep: the muscle found on the backside of your upper arm.

Important Muscles Quadriceps: the muscles on the front of your thighs. Hamstrings: on the back of your thigh; a good test of your flexibility! Gastrocnemius: just a fancy way of saying your calf muscle (lower leg).

The Integumentary System The Human Body Systems The Integumentary System

Functions of the Skin Protects the body by keeping harmful substances out and necessary substances in. Regulate body temp; sweating cools your body, reduced blood flow to the skin heats your body. Eliminate waste (sweat) Gather information about environment (nerves) Produce Vitamin D using sunlight.

Structures of the Skin Epidermis: outer layer of the skin; cells are here for 2-3 weeks before they are shed. Melanin: pigment that colors skin. Dermis: inner layer of the skin; above fat layer and includes nerves, blood vessels, sweat glands, hairs, and oil glands. Pores: release sweat Follicles: strands of hair grow in follicles.

Healthy Skin Eating a balanced diet and drinking plenty of water Keeping your skin clean with mild soap Avoiding too much sun, which can harm skin cells and lead to skin cancer. Cancer: a disease in which cells divide uncontrollably