Muscle Tissue

Muscle tissue is tissue that allows for movement.

Muscle cells are excitable and they are contractile, meaning they can be shortened creating a pulling force. 

When muscle is connected to two different moveable bones, the muscle contracts pulling those two bones closer together to create movement.

Some muscle contractions are voluntary, meaning you decide to do it. Some muscle contractions are involuntary meaning you have no control over it. For example when bright light hits your pupal, it contracts. You have no control over this movement.

3 Types of muscle tissue

Skeletal Muscle Tissue

-Long cylindrical fiber that is striated. 

-For voluntary movement attached to bones

-Produces heat

-Protects organs

Cardiac Muscle Tissue

-Short, Branched, and striated

-Contracts to pump blood

Smooth Muscle Tissue

-Involuntary movement

-Moves food, respiration, and secretion

Watch this video to learn more about muscle tissue. In looking through a microscope how could you distinguish skeletal muscle tissue from smooth muscle? 

Student Activity:

Turn to Pages 11 and 12 of your coloring book. Follow the instructions for coloring.

Nervous Tissue

Nervous tissue is characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information. Two main classes of cells make up nervous tissue:

the neuron and neuroglia 

Follow this link to learn more about nervous tissue. What are the main parts of a nerve cell? 

Nerves are used to send messages throughout the body. A nerve cells will send a message to a nearby muscle causing it to contract.

Student Activity:

Turn to page 13 of your coloring book. Follow the coloring instructions.

Tissue Injury and Repair

Inflammation is how your body responds to injury. Whether biological, chemical, physical, or burns, all injuries lead to the same sequence of physiological events. Inflammation limits the extent of injury, partially or fully eliminates the cause of injury, and initiates repair and regeneration of damaged tissue.

Necrosis, or accidental cell death, also causes inflammation. 

Apoptosis is programmed cell death, a normal step-by-step process that destroys cells no longer needed by the body.  This does not cause inflammation. 

If inflammation persists, it becomes chronic and leads to diseased conditions. Arthritis and tuberculosis are examples of chronic inflammation. The suffix “-itis” denotes inflammation of a specific organ or type, for example, peritonitis is the inflammation of the peritoneum, and meningitis refers to the inflammation of the meninges, the tough membranes that surround the central nervous system 

The four signs of inflammation are redness, swelling, pain, and local heat

Student Activity:

Turn to page 14 of your coloring book. Follow the coloring instructions.

A primary union describes the healing of a wound where the edges are close together. When there is a gaping wound, it takes longer to refill the area with cells and collagen. The process called secondary union occurs as the edges of the wound are pulled together by what is called wound contraction. When a wound is more than one quarter of an inch deep, sutures (stitches) are recommended to promote a primary union and avoid the formation of a disfiguring scar. Regeneration is the addition of new cells of the same type as the ones that were injured. 

Watch this video to see the skin healing process. What is the process and how long does it take? 

Students Read:

Tissues and Cancer

Cancer is a generic term for many diseases in which cells escape regulatory signals. Uncontrolled growth, invasion into adjacent tissues, and colonization of other organs, if not treated early enough, are its hallmarks. Health suffers when tumors “rob” blood supply from the “normal” organs.

A mutation is defined as a permanent change in the DNA of a cell. Epigenetic modifications, changes that do not affect the code of the DNA but alter how the DNA is decoded, are also known to generate abnormal cells. Alterations in the genetic material may be caused by environmental agents, infectious agents, or errors in the replication of DNA that accumulate with age. Many mutations do not cause any noticeable change in the functions of a cell. However, if the modification affects key proteins that have an impact on the cell’s ability to proliferate in an orderly fashion, the cell starts to divide abnormally. As changes in cells accumulate, they lose their ability to form regular tissues. A tumor, a mass of cells displaying abnormal architecture, forms in the tissue. Many tumors are benign, meaning they do not metastasize nor cause disease. A tumor becomes malignant, or cancerous, when it breaches the confines of its tissue, promotes angiogenesis, attracts the growth of capillaries, and metastasizes to other organs. The specific names of cancers reflect the tissue of origin. Cancers derived from epithelial cells are referred to as carcinomas. Cancer in myeloid tissue or blood cells form myelomas. Leukemias are cancers of white blood cells, whereas sarcomas derive from connective tissue. Cells in tumors differ both in structure and function. Some cells, called cancer stem cells, appear to be a subtype of cell responsible for uncontrolled growth. Recent research shows that contrary to what was previously assumed, tumors are not disorganized masses of cells, but have their own structures.

Watch this video to learn more about tumors. What is a tumor?