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P & A Notes Chapter 5

February 07, 2011

Connective Tissue

- The cells are usually farther apart than epithelial cells. The intercellular material that fills the space between the cells is called matrix.

Matrix is made up of fibers and a ground substance that can be fluid, semi-solid to solid.

- Connective tissue cells can usually reproduce. Most types have a good blood supply and are well nourished.

General Cell Types:

*Fibroblasts- Usually star shaped. Produce fibers in the matrix.

*Macrophages- Function to move about & clean up foreign particles & in defense. Can carry on phagocytosis.

*Mast Cells- widely distributed in connective tissue. Release heparin to prevent blood clotting. Release histamine to promote reactions with inflammation and allergies.

* Collagenous (white) fibers- Thick, flexible, but not very elastic. Very strong. Made of protein collagen. Found in structures that hold parts together.
Tendons- muscle to bone
Ligaments- bone to bone

*Elastic (yellow) fibers- Thin, elastic (stretch), made of protein elastin.
Found in parts that stretch....skin, vocal cords, ear...

*Recticular Fibers- very thin, highly branched, form support in most connective tissue.

The Nine types of Connective Tissue;

1.) Loose Fibrous Connective Tissue:
-The cells in this tissue are mostly fibroblasts. The matrix is gel-like and contains many collagenous and elastic fibers. It is found binding the skin to the underlying organs, fills spaces between muscles and is found beneath most layers of epithelium. It has a very rich blood supply and is responsible for holding much tissue fluid.

2.) Adipose Tissue:
- When you overeat the fibroblasts in loose connective tissue store fat droplets in their cytoplasm and enlarge. When these cells become very numerous, we get adipose tissue.
-they function to cushion joints and some organs (kidneys), insulate, store energy.

3.) Dense Fibrous Connective Tissue:
-Has few cells, most of which are fibroblasts.
-It is made-up mostly of collagenous fibers that are tightly packed into the tissue.
-Blood supply is poor...little or no repair.
-Tendons, ligaments, whites of eyes and in deeper skin layers.

Cartilage: There are 3 types of cartilage, each type has a different type of matrix. They lack a direct blood supply...little or no repair. Their cells are called chondrocytes. These cells are found in a small open space called lacunae, and are completely surrounded by matrix.

4.) Hyaline Cartilage:
-the most common
-has fine collagenous fibers embedded in its gel-like matrix. (white plastic)
-ends of bones, soft part of nose, rings of trachea, provides frame work for developing bones.

5.) Elastic Cartilage:
-contains many elastic fibers in its matrix
-external ear, parts of larynx

-contains many large collagenous fibers making it a very tough tissue.
-serves as a shock absorber
-intervertebral disks, knee and pelvic girdle

7.) Bone:
-the most rigid connective tissue
-its matrix contains collagen and mineral salts
-supports body, protects organs, attachment for muscles, formation of blood cells, and stores inorganic salts...calcium and phosphorus
-Osteonic canals (Haversion canals contain a blood vessel. Bone is deposited in thin layers called lamellae around these canals.
Bone cells, osteocytes, are found in lacunae forming rings around the osteomic canal. Each osteomic canal with its rings of matrix and osteocyes is called an osteon (Haversion system). Many osteons make-up bone. Each bone cell is very close to blood, so healing is fairly rapid. the osteocytes also have cytoplasmic extensions called canaliculi. These connect to nearby cells and to the osteonic canal...materials can move quickly <-->.

8.) Blood:
-Liquid matrix (plasma)
-cells...red blood cells- transports O2 and CO2. White blood cells-destroy pathogens and removes worn cells. Platelets- are cell fragments, help to clot blood.
Plasma transports nutrients, wastes, gases, vitamins and regulates body fluids.

9.) Reticuloendothelial tissue:
A special type of connective tissue that is scattered throughout the body.
-As a group the cells are phagocytic.
-Important in defending against infection.
-Found in blood, lungs, brain, bone marrow, spleen, liver, lymph glands.
-Most common cell is the macrophage.



4 major types of tissues:

1.)epithelial 2.)connective 3.)muscle 4.)nervous

Epithelial tissues:

- Covers all body surfaces, inside and out. Is also major tissue of glands.

- The underside of the epithelial tissue is always anchored to the connective tissue by a non living basement membrane.

-Epithelial tissue lacks blood vessels. They are nourished by substances that diffuse from underlying connective tissue, which are well supplied with blood vessels.

-Epithelium can reproduce cells rapidly, quickly healing injuries.

1.) Simple squamous epithelium:

-Single layer of thin flattened cells.
-Substance can easily pass through this tissue......So it is often found where diffusion and filtration are taking place.
-Air sacs of lungs where O2 and CO2 are exchanged.
-Forms walls of capillaries where much diffusion and filtration is taking place.
-Lines inside of blood vessels and covers membranes that line body cavities and covers organs.

2.)Simple cuboidal epithelium:

-Cube shaped cells.
-Covers the ovaries, lines kidney tubules and the duct of various glands. (salivary, thyroid, pancreas, liver) In the kidney it is involved with secretion and absorption; in the other glands it is involved with he secretion of that glands products.

3.) Simple Columnar epithelium:

-Longer than they are wide.
-Lines stomach & intestines.
-Lines the untrue.
-Provide a protective layer to the underlying tissues.
-Have goblet cells scattered throughout that produces mucus, which lines and protects the cells. (digestive juices)
-In the stomach & intestine, the secretion of digestive fluids & absorption of nutrients.

4.) Pseudostratified columnar epithelium:

-Lines he respiratory system, and various tubes of the reproductive system.
-cells have cilia and goblet cells.
In respiratory system mucus catches dust and microbes, the cilia moves this mucus and trapped particles up and out of the airways.
In reproduction tubes, cilia aid in moving sex cells from one region to another.

5.) Stratified Squamous Epithelium:
-Consists of many layers of cells making this tissue thick.
-Cellular reproduction occurs in the deeper layers...as newer cells, grow older ones are pushed further outward.
-Forms outer layer of skin, linings of the mouth cavity, throat, vagina, and anal canal.

6.) Transitional epithelium:

Function: stretches and protection
-lines urinary bladder and passageways.
-made up f several layers of cuboidal cells.
-when stretched it may only have a few layers.

7.) Glandular epithelium:

-Composed of cells specialized to produce and secrete substances.
Exocrine glands secrete heir products into ducts that open into an internal or external surface.
Endocrine glands are ductless glands that secrete directly into blood or tissue fluid (ch. 11)
-Exocrine glands are classified according to their secretions. Do they contain only cell secretion, portions of cells, or entire disintegrating cells?
Merocrine glands, aporine glands, holocrine glands. (fig 5.9 pg 103, chart 5.3 pg 103)
-Most merocrine glands are divided into serous cells and mucous cells.
Serous cells- produce serous fluid a thin watery fluid. Found in the serous membranes that line he body cavities and cover the organs hey contain.
Mucous cells- produce a thick stringy mucus (rich in the glycoprotein mucin).


Muscle and Nervous
Muscle Tissue:
- Are contractile. Their elongated cells or fibers can change to become shorter and thicker.
As they contract the fibers pull on their attached ends and the body parts move.

1.) Skeletal muscle tissue:
- Found in muscle usually attached to bone.
- Controlled by conscious effort. (voluntary muscle)
- The cells are long and threadlike with alternating light and dark crossmarkings called striations.
- Each fiber has many nuclei, which are located on its surface.
- Responsible for moving the head, trunk, and limbs.

2.) Smooth muscle tissue:
- Called smooth muscle because it lacks striations.
-Found in the walls of the stomach, intestines, urinary bladder, uterus, and blood vessels.
- Cannot be stimulated by conscious effort. (involuntary muscle)
- Shorter than skeletal with one centrally located nucleous.
-Responsible for: Movement that forces food through the digestive tube (peristalysis). Constricting of blood vessels. Emptying of the urinary bladder.

3.) Cardiac muscle tissue-
- Found only in the heart.
- Have striaions, but not as prominent as skeletal muscle.
- Cells join end to end at a point called the intercalated disk.
- Each cell has a single nucleus.
- It is involuntary.
- makes up the bulk of the heart.
- Responsible for moving blood through the heart chambers and blood vessels.
Nerve Tissue:
- Found in brain, spinalcord, and associated nerves.
- Basic cell is neurons.
- Neurons are sensitive to certain types of change in their surrounding they respond by transmitting nerve impulses to muscles or glands.
- Coordinate and regulate body functions.
- Also contains neuroglial cells. They support and bind nerve tissue together, carry on phagocytosis and connect neurons to blood vessels.



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