THE SKELETAL, MUSCULAR AND INTEGUMENTARY SYSTEMS

Chapter 22

What does your skeletal system do for you?

1. PROTECTION- Heart & lungs protected by your ribs, your brain is protected by the skull

2. STORAGE- Bones store minerals that help your nerves and muscles. Long bones store fat- that can be used for energy.

3. MOVEMENT- Skeletal muscles pull on bones to produce movement. Without bones you cannot sit, walk or run!

4. BLOOD CELL FORMATION- Some of your bones are full of marrow- this makes blood cells.

Bones of the Skull

Vertebral Column Expanded View

What makes up the skeletal system?

Bones, cartilage, and the connective tissue that holds bones together make up your skeletal system.

HOW ARE YOUR BONES STRUCTURED? A bone is a living organ made of several different tissues. Bone is made of connective tissue and minerals.

TYPES OF BONE TISSUE:

1. compact bone- does not have any visible open spaces, rigid and dense

2. spongy bone- Bone tissue that has many open spaces, provides most of the strength and support for a bone

3. marrow – soft tissue contained in bones and stores fat (Red and Yellow Marrow)

TYPES OF JOINTS… JOINT- A PLACE WHERE TWO ORE MORE BONES MEET.

Joints are held together by ligaments. Ligaments are strong elastic bands of connective tissue. They connect the bones in a joint.

What does it mean to be double-jointed?

• The term double-jointed is an inaccurate way of saying that someone has hyper-mobility of their joints. Double-jointed would imply that the individual has more joints than normal or that their joints have a twice-normal motion — neither of these is true. The truth is that people who are called "double-jointed" have joints with more mobility than normal. In some individuals, this is normal. In others, there is an underlying medical reason for the joint laxity. For example, people with Ehlers-Danlos syndrome have abnormal connective tissue, allowing for excessive joint motion.

SKELETAL SYSTEM ISSUES Diseases of the skeletal system:

Osteoporosis is a disease that causes bones to become less dense. Bones become weak and break more easily.

Parts of the skeletal system can be injured:

Bones may be fractured, or broken.

Joints can also be injured. A dislocated joint is a joint in which one or more bones have been moved out of place.

Another joint injury, called a sprain, happens if a ligament is stretched too far or torn.

Function of the Muscular System

• Responsible for the movement of the human body.

• Attached to the bones of the skeletal system are about 700 named muscles that make up roughly half of a person's body weight.

• Each of these muscles is a discrete organ constructed of skeletal muscle tissue, blood vessels, tendons, and nerves.

WHAT ARE THE THREE TYPES OF MUSCLES?

Skeletal muscle - move us around and responsible for most of our behavior; most attached to bones at each end via tendons stimulation or hormones or may be rhythmic; striated and voluntary

Cardiac muscle - found in the heart, acts like rhythmic smooth muscle, modulated by neural activity and hormones; which is striated and involuntary

Smooth muscle - controlled by the autonomic nervous system; may either be generally inactive and then respond to neural ; which is non striated and involuntary

Muscles of the Body

Skeletal muscle cells are elongated or tubular. They

have multiple nuclei and these nuclei are located on the

periphery of the cell. Skeletal muscle is striated. That is,

it has an alternating pattern of light and darks bands that

will be described later.

Cardiac muscle cells are not as long as skeletal muscles

cells and often are branched cells. Cardiac muscle cells

may be mono-nucleated or bi-nucleated. In either case the

nuclei are located centrally in the cell. Cardiac muscle is

also striated. In addition cardiac muscle contains

intercalated discs.

Smooth muscle cell are described as spindle shaped.

That is they are wide in the middle and narrow to

almost a point at both ends. Smooth muscle cells have

a single centrally located nucleus. Smooth muscle cells

do not have visible striations although they do contain

the same contractile proteins as skeletal and cardiac

muscle, these proteins are just laid out in a different

pattern.

HOW DO MUSCLES WORK?

Muscles Attach to Bones • Strands of tough connective tissue

connect your skeletal muscles to your bones. These strands are called tendons. When a muscle that connects two bones gets shorter, the bones are pulled closer to each other. For example, tendons attach the biceps muscle to a bone in your shoulder and to a bone in your forearm. When the biceps muscle contracts, your forearm bends toward your shoulder.

•

Muscles Work in Pairs Your skeletal muscles often work in pairs. Usually, one muscle in the pair bends part of the body. The other muscle straightens part of the body. A muscle that bends part of your body is called a flexor (FLEKS uhr). A muscle that straightens part of your body is an extensor (ek STEN suhr). As shown in the figure below, the biceps muscle of the arm is a flexor. The triceps muscle of the arm is an extensor.

The Integumentary System

Integumentary Systems

• consists of the skin, hair, nails, glands, and nerves. Its main function is to act as a barrier to protect the body from the outside world. It also functions to retain body fluids, protect against disease, eliminate waste products, and regulate body temperature.

Integumentary Fun Facts

• Skin is the body's largest organ.

• You have a whole new layer of skin every month.

• We lose 30,000 to 40,000 dead skin cells every minute!

• An adult has 20 SQUARE FEET of skin!

• Hair grows about one centimeter per month.

• You shed a surprising 40 lbs of skin in a lifetime.

• Bed bugs exist solely to eat our dead skin.

• Your nails grow .5 mm a week.

Hair and Nails

• Keratin is a protein made by cells in your skin that make up your hair and nails. As keratin cells naturally push upward through the skin, they die and then harden, turning into your hair or nails. Known as keratinization, this process is what makes hair and nails grow, and several factors contribute to its sustained momentum. Hair grows an average of 3 inches a year, whereas nails usually grow about 1 1/2 inches a year.