Unit 3 Compendium Review

This is a picture of cardiac muscle.

This is a picture of skeletal muscle.

This is a smooth muscle.

This is a picture of muscle contraction.

This is a picture of the vertabrae column.

This is a picture of the bones in your face. It is a good thing to know.

Outline:
1. Functions of the Skeleton
supports the body
produces blood cells
stores minerals and fats
flexible body movement

2. Bones of the face
frontal
zygomatic
maxillae
mandible

3. Vertebral Column
cervical
thoracic
lumbar
sacrum
coccyx

4. Types of Muscles
smooth
cardiac
skeletal

5. Movement
muscular
skeletal

6. Bones store and release calcium
calcium




Functions of the Skeleton
The skelton supports the body. The bones of the legs support the entire body when we are standing and bones of the pelvic girdle supports the abdominal cavity.
The skeleton protects soft body parts. The bones of the skull protect the brain, the rib cage protects the heart and lungs. The vertebrae protect the spinal cord which makes nervous connections to all the muscles of the limbs.
The skelton produces blood cells. All bones in the fetus have red bone marrow that produces blood cells. In the adult only certain bones produce blood cells.
The skeleton stores minerals and fat. All bones have a matrix that contains calcium phosphate a source of calcium ions and phosphate ions in the blood. Fat is stored in yellow bone marrow.
The skeleton along with muscles permits flexible body movement. While joints occur between all the bones we associate body movement in particular with the bones of limbs.

Bones of the face
The frontal bone forms the forehead and eyebrow ridges, the zygomatic bones form the cheekbones, and the maxillae have numerous functions. They assist in the formation of the eye sockets and the nasal cavity. They form the upper jaw and contain sockets for the upper teeth. The mandible is the lower jaw with sockets for the lower teeth. The mandible has a projection we call the chin. The maxillae, frontal, and nasal bones help form the external nose. The exterior portion of ears are formed only by cartilage and not by bone, while the nose is a mixture of bones, cartilage, and connective tissues. The cartilage complete the tip of the nose and fibrous connective tissue forms the flared sides of the nose.

Vertebral Column
The vertebral column consists of 33 vertebrae. The vertebral column forms when the vertebrae join. The spinal cord which passes through the vertebral canal gives off the spinal nerves at the intervertebral foramina. The spinous processes of the vertebrae can be felt as bony projections along the midline of the back. The spinous processes and also the transverse processes which extend laterally serve as attachment sites for the muscles that move the vertebral column. The various vertebrae are named according to their location in the vertebral column. The cervical vertebrae are located in the neck. The first cervical vertebra called the atlas holds up the head. It allows the head to tilt from side to side. The second cervical vertebra is called the axis because it allows a degree of rotation. The thoracic vertebrae have long thin spinous processes and articular facets for the attachment of the ribs. Lumbar vertebrae have a large body and thick processes. The five sacral vertebrae are fused together in the sacrum. The coccyx is usually composed of four fused vertebrae. Between the vertebrae are intervertebral disks composed of fibrocartilage that acts as a kind of padding. They prevent the vertebrae from grinding against one another and absord shock caused by movements such as running, or jumping. The presence of the disks allows the vertebrae to move as we bend forward, backwards, and from side to side. It can be painful if a disk is pressed against the spinal cord or nerves. In order to remember how many vertebrae there are remember the numbers 7,12,5,5,4.

Types of Muscles
We have three types of muscle tissue-smooth, cardiac, and skeletal. The cells of these tissues are called muscle fibers. Smooth muscle fibers are spindle shaped cells each with a single nucleus. The cells are usually arranged in parallel lines. Smooth muscle is located in the walls of hollow internal organs and it causes these walls to contract. Contraction of smooth muscle is involuntary occuring without conscious control. Cardiac muscle forms the heart wall. It's fibers are generally uninucleated , strained, tubular, and branched this allows the fibers to interlock at intercalated disks. The plasma membranes at intercalated disks contain gap junctions that permit contractions to spread quickly throughout the heart wall. Cardiac fibers relax completely between contractions which prevents fatigue. Contraction of cardiac muscles is rhythmical,it occurs without outside nervous stimulation and without conscious control. Cardiac muscle contraction is involuntary. Skeletal muscle fibers are tubular multinucleated and striated. They make up the skeletal muscles attached to the skeleton. They run the length of the muscle and can be long. Skeletal muscle is voluntary because we can decide to move a particular part of the body.

Movement
The skeletal and muscular systems work together to enable body movement.

This is most illustrated by what happens when skeletal muscles contract and pull on the bones to which they are attached causing movement at the joints. Body movement like this allows us to respond to certain types of changes in the environment. For instance: if you are outside and it starts to rain and you get wet then you can get up and get out of the rain. The muscular and skeletal systems work for other types of movements that are just as important for maintaining homeostasis. Contraction of skeletal muscles associated with the jaw and tongue allow you to grind food with the teeth. The smooth muscle contractions of peristalsis move ingested materials through the digestion tract. This is necessary for supplying the body's cells with nutrients. Contractions of skeletal muscles in the body aid in the process of venous return by pushing blood back toward the heart. So, the main point is muscles and bones work together to make movements.

Bones store and release calcium

The skeletal system performs tasks that are vital for calcium homeostasis. Calcium ions are needed for a variety of processes in your body such as muscle contraction and nerve conduction. They are also necessary for the regulation of cellular metabolism by acting in cellular messenger systems. It is always important to maintain an adequate level of calcium in the blood. When you have plenty of calcium in your blood the hormone calcitonin from the thyroid gland ensures that calcium salts are deposited in bone tissue. The skeleton acts as a reservoir for storage of this important mineral.