Nervous and Muscle Tissue, Membranes & Repair

Nerve Tissue Nervous tissue is divided into two types: Neurons Supporting cells

Neurons These generate and conduct the nerve impulses

Neurons These generate and conduct the nerve impulses The dendrites respond to stimuli

Neurons These generate and conduct the nerve impulses The dendrites respond to stimuli The nerve impulses are transmitted overlong distances by the axons.

Support Cells These are a mixed group of cells which support and insulate the neurons

Support Cells These are a mixed group of cells which support and insulate the neurons. Collectively they are called neuralgia (glial cells).

Support Cells There are four types: Astrocytes Microglia Ependymal cells Oligodendrocytes

Muscle Tissue These cells are responsible for movement

Muscle Tissue These cells are responsible for movement They are highly vascularized and cellular.

Muscle Tissue These cells are responsible for movement They are highly vascularized and cellular Muscle cells are filled with myofilaments

Muscle Tissue Muscle tissue is divided into three types: Skeletal Cardiac Smooth

Skeletal Muscle This attaches to bone and is responsible for voluntary motion.

Skeletal Muscle This attaches to bone and is responsible for voluntary motion. The muscle cells (muscle fibers) are cylindrical cells that contain many nuclei.

Skeletal Muscle This attaches to bone and is responsible for voluntary motion. The muscle cells (muscle fibers) are cylindrical cells that contain many nuclei. The skeletal muscles are called striated because of the arrangement of the myofibrils.

Meat

Skeletal Muscle

Cardiac Muscle This type is found only in the heart where its contractions propel blood through the body

Cardiac Muscle This type is found only in the heart where its contractions propel blood through the body It is striated but the cells are uninucleated

Cardiac Muscle This type is found only in the heart where its contractions propel blood through the body It is striated but the cells are uninucleated This muscle in involuntary.

Cardiac Muscle The cells are branched and connect to each other with unique junctions called intercalated disks.

Heart

Cardiac Muscle

Smooth Muscle Tissue These cells have no visible striations

Smooth Muscle Tissue These cells have no visible striations They are uninucleated and spindle shaped.

Smooth Muscle Tissue These cells have no visible striations They are uninucleated and spindle shaped. They are found lining the hollow organs such as the intestines, respiratory and urinary tracts and blood vessels.

Smooth Muscle Tissue These cells have no visible striations They are uninucleated and spindle shaped. They are found lining the hollow organs such as the intestines, respiratory and urinary tracts and blood vessels. They are involuntary

Smooth Muscle Tissue

Coverings and Membrane Linings The four tissues are incorporated into forming membranes which cover the body and its cavities.

Coverings and Membrane Linings The four tissues are incorporated into forming membranes which cover the body and its cavities. There are three types: Cutaneous Mucous Serous

Cutaneous Membrane This covers the exterior of the body and is commonly known as the skin.

Cutaneous Membrane This covers the exterior of the body and is commonly known as the skin. It has a layer of keratinized stratified squamous epithelium (epidermis) with a layer of dense irregular connective tissue below it.

Cutaneous Membrane This covers the exterior of the body and is commonly known as the skin. It has a layer of keratinized stratified squamous epithelium (epidermis) with a layer of dense irregular connective tissue below it. Because it is exposed to the air it is considered a dry membrane.

Mucous Membrane These line the body cavities that are open to the exterior; examples include the digestive, respiratory and urinary tracts.

Mucous Membrane These line the body cavities that are open to the exterior; examples include the digestive, respiratory and urinary tracts. These are moist membranes

Mucous Membrane The epithelium can be stratified squamous, pseudostratified columnar or simple columnar epithelium.

Mucous Membrane The epithelium can be stratified squamous or simple columnar epithelium. Underneath this is a layer of loose Areolar connective tissue forming the lamina propria.

Mucous Membrane The epithelium can be stratified squamous or simple columnar epithelium. Underneath this is a layer of loose Areolar connective tissue forming the lamina propria. Below this can be a layer of smooth muscle.

Mucous Membrane

Serous Membranes These are the moist membranes that cover the body’s cavities

Serous Membranes These are the moist membranes that cover the body’s cavities The membrane consists of a simple squamous epithelium (Mesothelium) resting on a layer of Areolar tissue.

Serous Membranes These are the moist membranes that cover the body’s cavities The membrane consists of a simple squamous epithelium (Mesothelium) resting on a layer of Areolar tissue. The Mesothelial cells secrete a fluid which lubricates the surfaces.

Mesothelioma

Tissue Repair Tissue injury is followed by a predictable series of steps which result in healing of the wound.

Tissue Repair Tissue injury is followed by a predictable series of steps which result in healing of the wound. These steps involve a nonspecific inflammatory response followed by repair which can result in either replacement of the tissue or fibrosis (scarring).

1. Inflammation This occurs right after the injury and involves cells such as the macrophages, mast cells and lymphocytes (normal residents of the Areolar tissue) releasing factors which lead to increased vascular permeability and stimulation of cell division.

2. Organization Once the blood clot is formed, it is replaced by granulation tissue. This is a collection of capillaries and fibroblasts which lay down a new matrix.

3. Regeneration or Fibrosis Epithelial, bone, areolar, dense irregular and blood tissues regenerate.

3. Regeneration or Fibrosis Epithelial, bone, areolar, dense irregular and blood tissues regenerate. There is little or no scarring. Smooth muscle and dense regular connective tissue have a moderate capacity to regenerate while skeletal muscle and cartilage are weak.

3. Regeneration or Fibrosis Epithelial, bone, areolar, dense irregular and blood tissues regenerate. Smooth muscle and dense regular connective tissue have a moderate capacity to regenerate Skeletal muscle and cartilage are weak. Cardiac and nervous tissues have none. The weaker the regeneration, the greater the scarring

Scarring

Factors Influencing Repair

So Why Do We Get Old?