THE SKELETAL, MUSCULAR, AND INTEGUMENTARY SYSTEMS

Chapter 22 Sections

Bones of the Skull

Vertebral Column Expanded View

Muscles of the Body

What makes up the skeletal system?

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

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.

HOW ARE YOUR BONES STRUCTURED?

A bone is a living organ made of several different tissues. Bone is made of connective tissue and minerals.

2 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 TYPE 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 hypermobility 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.

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

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 Summary