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Structural Organisation in Animals

Structural Organisation in AnimalsNEET Zoology · Class 11 · NCERT Chapter 7

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3 interactive concept widgets for Structural Organisation in Animals. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.

On this page

Epithelial, connective, muscular and neural tissue
Squamous, cuboidal, columnar, ciliated, compound, glandular
Earthworm vs cockroach vs frog

Animal tissue explorer

Explore the four animal tissue types: epithelial, connective, muscular and neural, with subtypes, locations and functions.

Animal tissues

Four animal tissue types: click to explore

Select any of the four tissue types to see its subtypes, typical locations, main functions and the NEET fact most commonly tested about it.

Epithelial
Connective
Muscular
Neural

Epithelial Tissue

Covers all external and internal body surfaces. Cells are tightly packed with very little matrix. Avascular (no blood vessels). Rests on a basement membrane.

Main function

Protection, absorption, secretion, filtration, sensory reception

Subtypes and locations

Simple squamous

Blood vessels (endothelium), body cavities (mesothelium)

Simple cuboidal

Kidney tubules, salivary gland ducts, thyroid follicles

Simple columnar

Stomach lining, intestine, gall bladder

Ciliated columnar

Trachea, bronchi, fallopian tubes

Compound (stratified)

Skin, oral cavity, oesophagus

Glandular

Exocrine glands (sweat, salivary) and endocrine glands (thyroid)

NEET fact

Epithelium is avascular and regenerates rapidly. The basement membrane separates it from the connective tissue below.

Try this

  • Which tissue type is avascular (has no blood supply inside it) and must get nutrients by diffusion?
  • Cardiac muscle is both involuntary and striated. What structural feature allows the heart to beat as one unit?
  • Blood is classified as a connective tissue. What is the extracellular matrix of blood called?

Epithelial tissue comparator

Compare epithelial tissue subtypes with a cross-section sketch, location and function for each.

Epithelial tissue

Epithelial tissue subtypes: cross-section diagrams

Select any epithelial subtype to see a simple cross-section sketch, its number of layers, where it is found, what it does and the NEET fact tested about it.

Simple Squamous
Simple Cuboidal
Simple Columnar
Ciliated Columnar
Compound (Stratified)
Glandular
basement membraneflat cells (single layer)

Simple Squamous

Layers

Single layer

Location

Blood vessels (endothelium), body cavities (mesothelium), alveoli of lungs

Function

Diffusion and filtration across a thin surface; reduces friction in vessels

NEET fact

Simple squamous epithelium lining blood vessels is called endothelium; lining body cavities it is called mesothelium.

Try this

  • Click Ciliated Columnar and Simple Columnar. Both are tall cells. What is the key difference in their function?
  • Which epithelial type is found in the PCT of the kidney? What structural feature helps it absorb so much?
  • Compound epithelium has multiple layers. Why does it NOT absorb nutrients even though it lines parts of the digestive tract?

Model organism comparator

Compare the earthworm, cockroach and frog across habitat, body plan and every organ system.

Model organisms

Earthworm, cockroach and frog: side-by-side comparator

Select any feature row (circulation, respiration, excretion, etc.) to compare the earthworm, cockroach and frog side by side. A quick-reference table shows key differences for NEET.

Habitat
Body plan
Circulation
Respiration
Excretion
Nervous system
Reproduction

Circulation

Earthworm

Pheretima posthuma

Closed: blood confined to vessels at all times. Dorsal vessel pumps blood forward. Four to five pairs of aortic arches (hearts) in segments 7 to 11 pump blood to the ventral vessel.

Cockroach

Periplaneta americana

Open: haemolymph flows freely through body cavities (sinuses). A muscular dorsal tubular heart (13 chambers) pumps haemolymph forward through an aorta. No respiratory pigment in blood.

Frog

Rana tigrina

Closed. Three-chambered heart: two atria (right and left) and one ventricle. Sinus venosus receives deoxygenated blood; conus arteriosus distributes it. Double circulation (systemic and pulmocutaneous circuits).

Quick reference

Feature

Earthworm

Annelida

Cockroach

Arthropoda

Frog

Chordata (Vertebrata)

Circulation

Closed

Open (haemolymph)

Closed (3-chambered)

Respiration

Moist skin

Trachea + spiracles

Skin, lungs, buccal cavity

Excretion

Nephridia

Malpighian tubules

Kidneys (mesonephros)

Nitrogenous waste

Urea (ureotelic)

Uric acid (uricotelic)

Urea (ureotelic)

Reproduction

Hermaphrodite

Dioecious, ootheca

External fertilisation

Try this

  • Click Circulation. Earthworm = closed; cockroach = open. What does this mean for how oxygen is delivered to cells in each?
  • Click Excretion and note that earthworms use nephridia while cockroaches use Malpighian tubules. Which excretory product does each animal produce?
  • The frog uses three respiratory surfaces. Which one is most important for CO2 removal, and why does it work?

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Animal Kingdom

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Biomolecules

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