Structural Organisation of Animals🟡

Question 1

All complex animals consist of only ____ basic types of tissues, namely -

Answer 1

Four:
Epithelial, Connective, Muscular and Neural

Question 2

Tell about Epithelial Tissues and their types

Answer 2

• Has Free Surface, which faces either body fluid or the outside environment and thus provide a covering or lining for some part of the body
• cells are compactly packed with little intercellular matrix

Two Types -
Simple Epithelium: Composed of single layer of cells and functions as a lining for body cavities, ducts and tubes.
Compound Epithelium: Consist of two or more cell layers and has protective function as in our skin.

Question 3

Explain types of Simple Epithelial Tissue and their locations

Answer 3

Squamous Epithelium: Single thin layer of flattened cells with irregular boundaries.
Found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary

Cuboidal Epithelium: Single layer of cube-like cells.
Found in ducts of glands and tubular parts of nephrons in kidneys and its main functions are secretion and absorption.
The Cuboidal Epithlium of proximal convulated tubule (PCT) of nephron in the kidney has microvilli
Columnar Epithelium: Single layer of tall and slender cells, nuclie at base, free surface may have microvilli
Found in the lining of stomach and intestine and help in secretion and absorption

Ciliated Epithelium: if the columnar or cuboidal cells bear cillia on their free surface
Their function is to move particals or muscus in specific direction over the epithelium.
Mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes

Question 4

Explain Glandular Epithelium and its types

Answer 4

Some of the columnar or cuboidal cells
get specialised for secretion and are called
glandular epithelium

Mainly of two types:

Unicellular: consisting of isolated glandular cells (goblet
cells of the alimentary canal)
Multicellular: consisting of cluster of cells
(salivary gland)

On the basis of the mode of pouring of their secretions

Exocrine glands: secrete mucus, saliva, earwax, oil,
milk, digestive enzymes and other cell
products. These products are released
through ducts or tubes.

Endocrine glands: do not have ducts. Their
products called hormones are secreted
directly into the fluid bathing the gland.

Question 5

Explain Compound epithelium

Answer 5

made of more than one layer (multi-layered) of cells and thus
has a limited role in secretion and absorption
Their main function is to provide protection against chemical and mechanical stresses.
They cover the dry surface of the skin, the moist surface of buccal cavity, pharynx, inner lining of ducts of salivary glands and of pancreatic ducts.