Structural Oraganisation in Animals

What are tissues?

Tissue are a group of similar cells having the same origin and performing a specific function.

study of tissues

histology

coined the term tissues?

in plants: N.Grew

in animals: Bichat

4 types of animal tissues?

1. Epithelial Tissues

2. Connective Tissues

3. Muscular Tissues

4. Nervous/ Neural Tissues

2 types of epithelial tissues

1. simple epithelial tissues (one single layer)

2. compound epithelial tissues(multiple layers)

types of simple Epithelium?

1. Squamous Epithelium

2. Cuboidal Epithelium

3. Coulumnar Epithelium

4. Ciliated Epithelium

5. Pseudostartified Epithelium

6. Glandular Epithelium

Characteristic of Epithelium?

Epithelium is made up of one of more layers of cells that covers or lines the external and internal surfaces of various body parts.

Structure of Epithelium

• variously shaped cells

• arranged closely

• little intercellular material

• has a basment mebrane

what is basment membrane?

Epithelium usually lies on a noncellular basment membrane which provides:

• elastic support

• supplies nutrients and O2 from C.T. to above lying C.T

  It has two parts:

  1. Basal Lamina : Outer thin layer (near epithelial cells)

  2. Fibrous or Reticular Lamina: Inner thicker layer.

Structure of Simple Squamous Epithelium Tissue

• thin layer

• flattend cells

• closely fitted cells

• polygonal shape

• flat and central buldge nucleus

Location of Simple Squamous Epithelium Tissue

• innermost linning of blood vessles(endothelium)

• air sacs (alveoli) of lungs (pneumocytes)

• lymph vessles

• ceolmic cavity

• loop of henle and walls of bowans capsule of nephron

Functions of Simple Squamous Epithelium Tissue?

• filtration

• exchange of gasses

• exchange of fluid materials between blood capillaries and tissue fluid

• covering/ lining of organ

Structure of Simple Cuboidal Epithelium Tissue

• cube like

• cental rounded nuclei

• free surfaces may bear microvilli

Location of Simple Cuboidal Epithelium Tissue

• tubularpart of nephron

• ducts in glands

• thyroid follicle

• gonads (germinal epithelium)

Functions of Simple Cuboidal Epithelium Tissue

• microvilli presnt is responsible for reabsorption of useful materials

• secretion and excreation by glands

Structure of Simple Columnar Epithelium

• tall and slender cells

• nuclei is at base; elongated

• may bear microvilli

• may produce mucus- goblet cells

• also contain underlying supporting connective tissue called mucus or mucosa membrane.

Location of Simple Columnar Epithelium Tissue

• lining of stomach

• lining of intestine

Function of Simple Columnar Epithelium

• absorption

• secretion

Structure of Ciliated Epithelium

• bear cilia on their free surface

• cilia can vary from few to numerous

• the cilia remains in rythmic motion and create a current to transport the materials which come in contact with them.

Two types of Ciliated Epithelium

• Ciliated Cuboidal Epithelium( e.g. bronchioles)

• Ciliated Columnar Epithelium ( inner lining of hollow organs like fallopian tube)

Function of Ciliated Epithelium

• move mucus or particles in a specific direction over the epithelium

• in respiratory tarct responsible for expelling mucus and particles trapped in it towards pharynx.

• in fallopian tube responsible for passage of ovum.

Structure of Psuedostratified Epithelium

• columnar

• unequal

• goblet cells also occur

Location of Psuedostratified Epithelium

• urethra of human male

• large ducts of certain glands( salivary and partoid gland)

• trachea and large bronchi

Location of Glandular Epithelium

• unicellular - alimentary canal, goblet canal

• multicellular - salivary, sweat,sebaceous lands

• exocrine - gastric, intestinal, oil, mammary, tear

• endocrine - adrenal.hypothalamus,pituitary,thyroid