Structural Organisation in Animals | Plus 1 Exam Capsule Notes (Web and PDF)



1. Epithelial tissues (Epithelium)

a. Simple (single layered)

    i. Squamous: 
  • Location: Walls of blood vessels and alveoli.
  • Function: Diffusion.
    ii. Cubical (cuboidal): 
  • Location: Ducts of glands and tubular parts of nephrons.
  • Function: Secretion & absorption
    iii. Columnar:
  • Location: Lining of stomach and intestine.
  • Function: Secretion & absorption
b. Compound (Multi-layered)
  • Location: Skin, buccal cavity, pharynx, pancreatic ducts.
  • Function: Protection.
Modification of columnar or cuboidal cells

i. Ciliated epithelium: 
  • Bear cilia.
  • Seen in bronchioles & fallopian tubes.
  • Function: move substances over epithelium.
ii. Glandular epithelium: 

    For secretion.

    2 types: Unicellular (E.g. Goblet cells) & Multicellular (E.g. salivary glands).

    Based on mode of secretion, glands are 2 types:
  • Exocrine glands: have ducts. E.g. Salivary gland.
  • Endocrine glands: Ductless. Produce hormones.
Cell junctions 

The junctions that provide link between adjacent cells.

They are 3 types: 
  1. Tight junction: Stop substances from leaking across a tissue.
  2. Adhering junction: Perform cementing to keep neighbouring cells together.
  3. Gap junction: For communication b/w adjoining cells by connecting cytoplasm for rapid transfer of ions, molecules etc.
2. Connective tissues 

3 Types: Loose, Dense & Specialised.

a. Loose CT

    Loosely packed Fibres and fibroblasts. 2 types: 
  • Areolar: Under skin. Support for epithelium.
  • Adipose: Under skin. Its cells (adipocytes) store fats.
b. Dense CT

    Compactly packed Fibres and fibroblasts. 

    2 types:
  • Dense regular (Tendon & Ligament): 
            Collagen fibres are regular. 
            Tendon: Attach muscles to bones. 
            Ligament: Attach bone to bone.
  • Dense irregular: Fibroblasts & fibres are irregular. Present in skin.
c. Specialized CT

    3 types: 

    i. Cartilage: 

        Pliable due to chondroitin salts. 
        Cartilage cells → chondrocytes.

    ii. Bone: 

        Non-pliable. Rich in calcium salts. 
        Bone cells → osteocytes.
        Function: Protection, support, locomotion.

    iii. Blood: 

        Fluid CT. 

3. Muscle tissues 

3 types: 
  1. Skeletal (striated or voluntary): Attached to bones. Striations present.
  2. Visceral (Non-striated/ smooth): Involuntary & fusiform. No striations. Found in blood vessels, stomach, intestine etc.
  3. Cardiac: Involuntary. Seen in heart. Communication junctions (intercalated discs).
4. Neural tissue

Found in Neural system. 

Made up of neurons & Neuroglia.

(Periplaneta americana

Chitinous exoskeleton (cuticle).

The body has 3 regions – head, thorax and abdomen.

  • Antennae, compound eyes. Biting & chewing mouth parts.
  • Mouthparts: labrum (upper lip), 2 mandibles, 2 maxillae, hypopharynx (tongue) & a labium (lower lip).

    3 parts: prothorax, mesothorax & metathorax.

    2 pairs of wings:
  • Forewings (mesothoracic) or tegmina: Opaque, dark.
  • Hind wings (metathoracic): Transparent, used in flight.
Abdomen: 10 segments. 

Differences between male & female cockroaches 



   i. Wings beyond the tip of the abdomen.

Wings up to the tip of abdomen.

 ii.  Anal styles present



Digestive system:

Alimentary canal has 3 parts: foregut, mid gut & hindgut.
  • Foregut: Mouth → pharynx → oesophagus → crop (to store food) → gizzard (proventriculus- for grinding food).
  • Mid gut (Mesenteron): 6-8 tubules (hepatic or gastric caecae) are seen at the junction of foregut & mid gut. They secrete digestive juice.
  • Hindgut: It includes ileum, colon & rectum.
Excretory system:
  • Uricotelic. 
  • Excretory organ is Malpighian tubules.
Respiratory system:
  • Trachea with 10 pairs spiracles. 
  • Branches of tracheal tubes are tracheoles. 
Circulatory system:
  • Open type.
  • Haemolymph (blood)= colourless plasma + haemocytes.
  • Blood from sinuses (haemocoel) → ostia → heart → anterior aorta → sinuses.
Nervous system: 
  • 3 ganglia in thorax and 6 in the abdomen.
  • The head holds only a bit of nervous system. So, if the head of cockroach is cut off, it will still live for one week.
  • Supra-oesophageal ganglion (brain).
    Sense organs: 
  • Antennae, eyes, maxillary palps, labial palps, anal cerci etc.
  • Each compound eye has 2000 ommatidia. 
  • Cockroach can receive several images of an object (mosaic vision).
Reproductive system:

A. Male reproductive system: 
  • 2 testes, seminal vesicles, accessory glands & external genitalia (male gonapophysis or phallomeres).
  • Testis → vas deferens → seminal vesicle → ejaculatory duct → male gonopore.
  • Seminal vesicles: To store sperms. Sperms → spermatophores.
  • Accessory glands: mushroom gland & phallic gland. They nourish the sperms.
B. Female reproductive system: 
  • 2 large ovaries, oviducts, spermatheca, genital chamber, Colleterial glands etc.
  • Each ovary has 8 ovarian tubules (ovarioles) containing developing ova.
  • Oviducts unite into a median oviduct (vagina) genital chamber.
  • A pair of spermatheca is present. 
  • Fertilised eggs are encased in oothecae.
  • Development is paurometabolous (nymphal stage).

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