SIMPLE EPITHELIAL TISSUE (EPITHELIUM)

*first animal tissue found in coelentrata.
*cells arranged in single or more than one layers, but the upper end of the layer is always free, means not covered.
*presence of basement membrane, which is made up of gylcoprotein and polysaccharide.
*epithelium divides throughout life.
*cell of epithelium are avascular
*Types of  epithelium on the basis of layer of the cell-

1. Simple epithelium
2. Compound/ Stratified epithelium

1. Simple epithelium-cells are arranged in single layer. it is further classified into three different group-

• Simple squamous epithelium/ Pavement
• Simple cuboidal epithelium/ Germinal epithelium
• Simple columnar epithelium

Simple squamous epithelium- cells are arranged like tiles or scales of fish.
-it contain very less quantity of matrix.
-cells are smaller in size.
-nucleus is at center of the cell.

-distribution- (a) Pericardium (covering of heart)- parietal pericardium, visceral pericardium, pericardial fluid.
                      (b)Bowman's capsule-it is a part of nephron in kidney.
                      (c)Pleura of lungs- it is covering.

Simple cuboidal epithelium- it contain very less quantity of matrix.

-it is also known as germinal epithelium.
-thyroid follicle of thyroid gland are made up of cuboidal epithelium.

Simple columnar epithelium- cells are column like or row like.
-nucleus present towards the base.
-it contain less quantity of matrix.

Modification of simple columnar epithelium

(1) Ciliated epithelium- presence of small hairy structure on free surface of the cell, called cilia.
-it performs specialised function.
-it present in neck of nephron.
-cilia of nephron helps in movement of filtrate from anterior end to posterior end.
- it is also found in alveoli of lungs.

-it also conduct egg in fallopian tube.

(2)Sensory epithelium- cells of columnar epithelium modified to receive stimulus.
-it is found in taste bud of tongue.
-it is also found in organ of corti.
-also present in rod and cones of retina of eye.
-schnederian membrane of nasal tube.

(3)Glandular epithelium- cells of columnar epithelium modified to form glands and gland specialised for secretion of substance.
               Types of glands on the basis of number of cells present in gland.-
#Unicellular glands- these gland contains only one cell. e.g.- goblet cell( found in intestine of human and secretes mucus), ebner's gland(present in tongue and secretes lipid digestive enzyme).

#Multicellular glands-these gland contain more than one cells. e.g.- salivary gland, ovary, testis, liver, pancreas,thyroid, pituitary gland, lacrymal gland, mammary gland, sweat gland, parotid gland etc

              Types of glands on the basis of transportation-

#Exocrine gland-it has duct to transport their product. e.g.-salivary gland, lacrymal gland, mammary gland, liver etc.

#Endocrine gland-these are duct less gland, they circulate their product through blood. e.g.- thyroid, pituitary,thymus etc.

#Heterocrine gland-in this type of gland one part has duct and another is ductless. e.g.- pancreas.

            Types of glands on the basis of mode of secretion-

#Holocrine gland-in this type of gland their total cytoplasm releases in the form of secretory material.e.g- sebaceous gland.

#Apocrine gland-in this type of gland, small amount of cytoplasm releases in the form of secretory product. e.g.-mammary gland.

#Merocrine gland-in this type of gland the secretory product releases through diffusion.e.g.- mammary gland.

ANIMAL TISSUES, INTRODUCTION

*group of cells having similar origin and function but their structure may or may not be similar , is commonly called TISSUE.
*study of tissue is called Histology.
*father and founder of Histology - Marcello Malpighi
*Matrix- it is secretory product of cell in tissue. The quantity of matrix and chemical composition varies in different cell.
*first of all tissue appeared in animals of phylum coelentrata.

*on the basis of function tissues are classified into four types-

1. Epithelial tissue- FUNCTION- absorption, secretion, protection etc.
2. Connective tissue- FUNCTION- connection, binding, joining, attachment etc.
3. Muscular tissue- FUNCTION- contraction and relaxation, movement and locomotion.
4. Nervous tissue- FUNCTION- to receive stimulus and transport the transport the stimuli from one place to another.

MAMMALIA CLASS, VERTEBRATA.

*these animals are warm blooded, hairy and have mammary or milk producing glands.
*there are about 4.000 species of mammals found in world.
*they are the only animals which nourish their young once with milk.
*sebaceous glands(oil gland) and sudoriferous glands(sweat gland) are present in the skin.
*teeth are heterodont and thecodont(embedded in the shocket of jaws). they develop twice in a life hence it is diphyodont
*they possess a muscular diaphragm dividing trunk into thorax and abdomen.
*mammals possess seven cervical vertebrae, except few.
*the skull is dicondylic.
*the heart is four chambered.
*the coelom is divided into four cavities- a pericardial cavity, two pleural cavities and an abdominal cavity.
*12 pair of cranial nerve.
*each consists of three parts,external, middle and internal. pinna is a part of external ear
*a copulatory organ is always present.
*fertilization is internal.
*except egg laying animal they are viviparous.
*sub-class are Prototheria and Theria
*e.g.-kangaroo, opossum, human etc

OPOSSUM

HUMAN

KANGAROO

AVES-CLASS, VERTEBRATA

*about 9000 species of aves are found
*they are warm blooded animal.
*they have bipeadal feather.
*their fore-limbs are modified into wings.
*the hind limbs are adapted for perching, walking or swimming.
*only preen gland(oil gland) present on tail, and no other gland present on skin.
*Ostrich and parrot lack oil glands
*upper and lower jaws modified into beak,which lack teeth
*legs bear horny epidermal skin.
*respiration occurs in lungs.
*syrinx produces voice in birds not larynx.
*heart is four chambered, sinus venosus is absent.
*renal portal system is very much reduced.
*kidney is metanephric, which directly drain uric acid into cloca through ureter. urinary bladder is absent
*Reha americana (South American Ostrich ) is the only bird which has urinary bladder.
*cerebrum, cerebellum and optic lobes are developed organ of brain.
*birds have 12 pair of cranial nerves.
*bones are pneumatic,means they have air cavity to reduce weight , which helps in flying.
*skull is monocondylic.
*female has well developed single left ovary and oviduct.if right ovary and oviduct are present then they are non-functional.
*sexual dimorphism is found in many birds.
*fertilization is internal
*birds are oviparous, means they lay eggs.
*e.g.-Ostrich, Kiwi. Penguins, Parrot, Duck

OSTRICH

KIWI

PENGUINS

REPTILIA CLASS, VERTEBRATA

*they are about 6000 species
*reptilia are creeping and burrowing cold blooded animals.
*they bear scales
*skin is dry, rough and without scales.
*respiration is by lungs.
*skull is monocondylic.
*except in snake there are two pair of pentadactyl limbs, each with 5 digits bearing claws.
*heart bear two auricles and partly divided ventricles
*kidneys are metanephric
*12 pairs of cranial nerves are present
*ear consists of three parts- internal, middle anr wxternal.
*snake do not possess ear.
*all reptiles are carnivorous/insectivorous, only tortoise feed entirely on vegetation.
*a typical cloaca is present.
*fertilization is internal
*e.g-Chelone(turtle), Testudo(tortoise), Chameleon(tree lizard),Naja(cobra),Bangarus(karait) etc

TESTUDO

CHELONE

NAJA

AMPHIBIA CLASS, VERTEBRATA

*It includes 3000 species.
*they are first evolved cold blooded land living animals.
*they can live on both land and water
*glands present on skin which keep it moist.
*two pairs of limbs for locomotion.
*skull is dicondylic.
*respiratory organs are lungs,buccopharyngeal cavity , skin and gills.
*heart are three chambered.
*kidneys are mesonephric.
*ear consists of internal and middle ear.
*10 pairs of cranial nerves are present.
*they breed in water.
*e.g.-Bufo (toad), Rana (frog),Hyla(tree frog), Salamandra (salamander), Ichthyophis(limbless amphibia).

BUFO

RANA

HYLA

SALAMANDRA

OSTEICHTHYES CLASS, VERTEBRATA

* habitat-both marine and fresh water fishes
* endoskeleton is cartilaginous in the embryonic stage, but in the adult forms it is replaced by bones.
*they are ectothermic( cold blooded)
* there body is streamlined
*the mouth is terminal, digestive tract leads into an anus.
*a swim bladder is usually present,helps in floating
*they have four pair of gills which are covered by an operculum
*the exoskeleton, if present comprises cycloid, ctenoid and ganoid scales.
*the heart is 2- chambered and has sinus venous and anteriosus.
* lung fishes have three chambered heart.
*kidneys are mesonephric.
*there are 10 pairs of cranial nerves.
*fertilization is generally external.
*e.g.- Labeo(rohu), Catla (katla), Muraena(eel)