Tissues

TISSUES

group of specialized cells and the extracellular substances surrounding them.

Histology

microscopic study of tissue structure

* Epithelial Tissues
* Connective Tissues
* Muscle Tissues
* Nervous Tissues

Types of Tissues:

Epithelium

upon covering

Epithelium

found virtually everywhere, both inside and outside the body

Epithelium

layers that covers the surfaces and line the hollow organs of our body

Free / Apical Surface

surface of epithelium that is exposed to the outside

Basal Surface

surface of the cells that is anchored in place

Lateral Surface

found between the epithelial cells where they are attached to each other.

1. Simple Epithelium
2. Stratified Epithelium
3. Pseudostratified Columnar Epithelium

Classifications of Epithelia based on number of layers:

Simple Epithelium

single layer of cell, each cell extending from the basement membrane to the free surface.

Stratified Epithelium

consists of more than one layer of cells, but only the deepest layer of cells attaches to basement membrane

Pseudostratified Columnar Epithelium

special type of simple epithelium

Pseudostratified Columnar Epithelium

consists of one layer but appears to be two or more layers because some of the cells are tall and extend to the free surface, whereas, others are shorter and do not extend to the free surface.

* Simple Squamous Epithelium
* Simple Cuboidal Epithelium
* Simple Columnar Epithelium
* Pseudostratified Columnar Epithelium
* Stratified Squamous Epithelium
* Transitional Epithelium
* Stratified Cuboidal Epithelium
* Stratified Columnar Epithelium

Classifications of Epithelial Tissues based on the shapes:

Simple Squamous Epithelium

single layer of flat, hexagonal cells

Simple Squamous Epithelium

has nuclei (like bumps)

Simple Squamous Epithelium

Examples:

Lung tissue

Glomeruli

lining of blood vessels (endothelium)

Simple Cuboidal Epithelium

single layer of cube-like cells

Simple Cuboidal Epithelium

with more organelles compared to squamous type

Simple Cuboidal Epithelium

others with cilia or microvilli

Simple Cuboidal Epithelium

Example: kidney tubules

Simple Columnar Epithelium

single layer of tall, thin cells

Simple Columnar Epithelium

contain organelles that enable them to perform complex functions

Simple Columnar Epithelium

some have cilia or microvilli

Simple Columnar Epithelium

with goblet cells

Simple Columnar Epithelium

Examples:

Fallopian tubes

Jejunum

Pseudostratified Columnar Epithelium

single layer of cells but cells appear to be layered due to the differing heights of adjacent cells and positions of their nuclei.

Pseudostratified Columnar Epithelium

special case of simple epithelium that has goblet cells

Stratified Squamous Epithelium

forms a thick epithelium because it consists of several layers of cells.

Stratified Squamous Epithelium

are cuboidal or columnar in basal layer and as they are pushed to the surface they become flat and thin.

Stratified Squamous Epithelium

may be keratinized or non-keratinized.

Non-Keratinized Stratified Squamous Epithelium

the surface cells retain a nucleus and cytoplasm

Keratinized Stratified Squamous Epithelium

the cytoplasm of the cells at the surface is replaced by a protein called keratin

Keratinized Stratified Squamous Epithelium

cells are dead

Transitional Epithelium

special type of stratified epithelium that can stretch

Transitional Epithelium

five or more cuboidal / columnar in unstretched state and transitions to flat / squamous and lesser cell layers

Stratified Cuboidal Epithelium

absorption, secretion & protection

Stratified Cuboidal Epithelium

sweat gland ducts

Stratified Cuboidal Epithelium

ovarian follicular cells

Stratified Columnar Epithelium

more than one layer of epithelial cells, but only the surface cells are columnar; deeper layer cells are irregular or cuboidal in shape

Stratified Columnar Epithelium

mammary gland ducts

Stratified Columnar Epithelium

larynx

Stratified Columnar Epithelium

part of male urethra

Connective Tissue

most abundant and widely distributed

Connective Tissue

diverse primary tissue type that makes up part of every organ in the body.

Extracellular Matrix

Cells

Basic Elements of Connective Tissues:

a)     Protein Fibers:

b)     Ground Substance

c)     Fluid

Components of Extracellular Matrix

1. Collagenous Fibers
2. Reticular Fibers
3. Elastic Fibers

Protein Fibers:

Collagenous Fibers

white, collagen, “rope” strong and flexible, loose or dense

Reticular Fibers

short & very fine, collagen

Reticular Fibers

form supporting network (Reticulum)

Elastic Fibers

yellow, elastin, not very strong but elastic

Elastic Fibers

“coiled metal bed springs”

Ground Substance

shapeless background which holds the cells and protein fibers

Ground Substance

with water and proteoglycans

1. Blasts
2. Cytes
3. Clasts
4. Mast
5. Macrophages

Cells in Connective Tissues

Blasts

create the matrix

Cytes

maintain the matrix

Clasts

break it down for remodeling

Mast

nonmotile cells that release chemicals such as histamine that promotes inflammation.

Macrophages

large white blood cells that are capable of moving about and ingesting foreign substances.

1. Loose / Areolar Connective Tissues
2. Adipose Connective Tissues
3. Dense Collagenous Connective Tissues
4. Dense Elastic Connective Tissues
5. Hyaline Cartilage
6. Fibrocartilage
7. Elastic Cartilage
8. Bone
9. Blood
10. Reticular

Classification of Connective Tissues:

Loose / Areolar Connective Tissues

“packing material of the body”

Loose / Areolar Connective Tissues

fills spaces between organs and hold them in place

Adipose Connective Tissues

with very little extracellular matrix

Adipose Connective Tissues

matrix with collagen & elastic fibers

Adipose Connective Tissues

nucleus & cytoplasm peripherally located

Adipose Connective Tissues

packing, thermal insulator, energy storage, protection of organs against injury from being bumped or jarred

Dense Collagenous Connective Tissues

matrix consisting mostly of collagen fibers which may be arranged in the same direction (dense regular) or in many different directions (dense irregular)

Dense Collagenous Connective Tissues

provide pulling strength along the axis of fibers

Dense Elastic Connective Tissues

has abundant elastic fibers that stretch and recoil

Dense Elastic Connective Tissues

same direction of fibers: ligaments between vertebrae, vocal cords

Dense Elastic Connective Tissues

different fiber directions: blood vessel wall

Hyaline Cartilage

most abundant type of cartilage connective tissue

Hyaline Cartilage

clear or glassy

Hyaline Cartilage

collagen fibers small and evenly dispersed

Hyaline Cartilage

ends of long bones

Hyaline Cartilage

tracheal/bronchial rings, costal cartilage, nasal cartilage

Hyaline Cartilage

forms smooth articulating surfaces

Hyaline Cartilage

forms embryonic skeleton

Fibrocartilage

with more collagen fibers than hyaline c.

Fibrocartilage

fibers arranged in thick bundles

Fibrocartilage

flexible & can withstand considerable pressure

Fibrocartilage

connects structures subjected to great pressure

Elastic Cartilage

with elastic fibers appearing as coiled fibers among bundles of collagen fibers

Elastic Cartilage

Examples are epiglottis and Auditory tubes

Bone

has mineralized matrix and forms most of the skeleton body

Spongy Bone

has spaces between trabeculae or plates of bone and therefore resembles a sponge.

Compact Bone

more solid, almost no space between many thin layers of mineralized matrix.

Blood

with liquid matrix and blood cells

Blood

transports substances, protects from infection, regulates temperature

Reticular

network of interlacing reticular fibers and reticular cells that are loosely arranged

Reticular

supporting framework (liver, spleen, lymph nodes)

Reticular

binds together smooth muscle tissue cells

Muscle Tissue

specialized to shorten or contract

Muscle Tissue

makes movements possible

1. Skeletal Muscle
2. Cardiac Muscle
3. Smooth Muscle

Types of Muscle Tissue:

Skeletal Muscle

attaches to skeleton

Cardiac Muscle

muscle of the heart