STRUCTURAL ORGANISATION IN ANIMALS notes
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October 15, 2015 |
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Tissue : A group of similar cells along with intercellular substances which perform a specific function.
Simple epithelium : is composed of a single layer of cells resting on a basement membrane.
Compound epithelium : consists of two or more cell layers and has protective
function.
Areolar tissue : is a type of loose connective tissue present beneath the skin.
Adipose tissue : is a type of loose connective tissue which has cells specialised to store fats.
Neuroglia : A delicate connective tissue which supports and binds together the nerve tissue in the Central Nervous Tissue.
Malpighian tubules : Yellow coloured thin, filamentous tubules present at the junction of midgut and hindgut in cockroach; helps in excretion.
Uricotelic : Animals which excrete nitrogenous waste in the form of uric acid.
Tight junctions : Plasma membranes of adjacent cells are fused at intervals.
They help to stop substances from leaking across a tissue.
Adhering junctions : Perform cementing function to keep neighbouring cells together.
Gap junction : Facilitate the cells to communicate with each other by connecting
the cytoplasm of adjoining cells for rapid transfer of ions, small molecules
and sometimes big molecules
Animal Tissues
Epithelial Connective Muscular Neural
Epithelial Tissue
Simple : • Composed of single layer of cells.
• Functions as lining for body cavities, ducts and tubes.
1. Squamous • single thin layer of flattened cells.
• found in walls of blood vessels, air sacs of lungs.
2. Cuboidal • single layer of cube like cells.
• found in ducts of glands and tubular parts of nephron.
3. Columnar • single layer of tall and slender cells.
• free surface may have microvilli.
• found in living of stomach and intestine.
4. Ciliated • columnar or cuboidal cells with cilia.
• move particles or mucus in specific direction, in
bronchioles, fallopian tubes.
Compound
• Made of more than one layer of cells.
• Provide protection against chemical and mechanical stresses.
• Cover dry surface of skin, moist cavity, pharynx, inner lining of ducts
of salivary glands and pancreatic ducts.
Glandular epithelium
Exocrine glands Endocrine glands
• secrete mucus, saliva, oil, milk, • secrete harmones.
digestive enzymes.
• products released through ducts. • secrete directly into the fluidbathing the gland.
Connective tissue : Link and support other tissues / organs of the body.
CONNECTIVE TISSUE
Loose Connective Tissue
(has cells and fibres loosely arranged in semi-fluid ground substance)
(i) Areolar Tissue :
• present beneath the skin.
• contains fibroblasts, macrophages and mast cells.
• serves as a support framework for epithelium.
(ii) Adipase Tissue :
• located beneath the skin.
• cells are specialised to store fats.
Dense Connective Tissue
Fibres and fibroblasts are compactly packed.
(i) Dense Regular
• Collagen fibres present in rows.
• Tendons attach skeletal muscle to bone.
• Ligaments attach bone to bone.
(ii) Dense Irregular
• Has collagen fibres and fibroblasts oriented differently.
• This tissue is present in the skin.
Specialised Connective Tissue
(i) Cartilage made up of chondrocytes and collegen fibres.
(ii) Bones Ground substance is rich in calcium salts and collegen
fibres Osteocytes are present in lacunae
(iii) Blood Fluid connective tissue, consists of plasma and blood cells
Muscle Tissue
Consists of long, highly contractile cells called fibres; bring about movement
and locomotion.
(i) Skeletal Muscle
• Consists of long cylindrical, multinucleated fibres.
• Closely attached to skeletal bones.
• Striated.
(ii) Smooth Muscles
• Consists of spindle like, uninucleated fibres.
• Do not show striations.
• Wall of internal organs such as blood vessels, stomach and intestine.
(iii) Cardiac Muscles
• Short, cylindrical, uninucleated fibres.
• Occur in the heart wall.
• Intercalated discs for communication.
Neural Tissue
• Neurons are the functional unit and are excitable cells.
• Neuroglia cells make up more than half the volume of neural tissue.
They protect and support neurons.
Cockroach − Periplaneta americana
is a terrestrial, nocturnal, omnivorous, unisexual, oviparous insect. Body
covered by a chitinous, hard exoskeleton of hard plates called sclerites.
Head : Triangular, formed by fusion of 6 segments. Bears a pair of antennae,
compound eyes. Mouth parts consists of labrum (upper lip), a pair of mandibles,
a pair of maxillae, labium (lower lip), hypopharynx (acts as tongue).
Thorax : 3 segments; prothorax, mesothorax and metathorax. Bears 2 pairs
of wings :
Forewings : tegmina (mesothoracic).
Hindwings : transparent, membranous (metathoracic) and 3 pairs of legs in
thoracic segments.
Abdomen : 10 segments. Bears a pair of long, segmented anal cerci in
both sexes and a pair of short, unjoined anal styles in males only.
Also has anus and genital aperture at the hind end. Genital aperture surrounded
by external genitalia called gonapophysis or phallomere.Anatomy : Study of the morphology of internal organs.
Alimentary canal : Divided into foregut, midgut and hindgut.
Mouth → Pharynx → Oesophagus → Crop (stores food) → Gizzard (grinding
of food) → Hepatic caeca (at junction of fore and midgut; secretes digestive
juice) → Hindgut (ileum, colon, rectum) → Anus.Blood vascular system : Open type, visceral organs bathed in haemolymph
(colourless plasma and haemocytes).
Heart consists of enlongated mascular tube and differentiated into funnelshaped
chambers with ostia on either side. Blood from sinuses enters heart through
ostia and is pumped anteriorly to sinuses again. Blood colourless (haemolymph).
Repiratory system : Network of trachea which open through 10 spiracles.
Spiracles regulated by sphincters. Oxygen delivered directly to cells. Excretion
and osmoregulation by Malpighian tubules; uricotelic (Uric acid as excretory
product).
Nervous system : Consists of series of fused segmentally arranged ganglia
joined by paired longitudinally connectives on the ventral side. three ganglia in
thorax, six in abdomen. Brain represented by supra-oesophageal ganglion.
Reproductive system :
Male − Pair of testes (4th-6th segments) → vas deferens → ejaculatory duct
→ male gonophore.
Glands − Seminal vesicle (stores sperms), mushroom shaped gland (6th-
7th segment).
Female reproductive system :
A pair of ovaries (with 8 ovarian tubules) → Oviduct → Genital chamber.
Sperms transferred through spermatophores. Fertilised eggs encased in capsules
called oothecae; development of P. americana paurometabolous (incomplete
metamorphosis). Nymph grows by moulting 13 times to reach adult form.
Interaction with man
• Pests as destroy food and contaminate it.
• Can transmit a variety of bacterial diseases (Vector).
QUESTIONS
Very Short Answer Questions (1 mark each)
1. Name the tissue which contains Haversian canals.
2. Mention two special properties of nervous tissues.
3. Name the large cells present in adipose tissue.
4. Name the cells responsible for clotting of blood.
5. What are exocrine glands ?Short Answer Questions-II (2 marks each)
6. What is the function of ciliated epithelium ? Where do we find this epithelium ?
7. What are the two types of fibres of connective tissues ? Distinguish between the two.
8. To which tissue do the following belong to :
(a) Osteocytes (b) Chondrocytes
(c) Neuroglia (d) Intercalated discs
9. Give the location of hepatic caecae in cockroach ? What is their function ?
10. Name the locomotory appendages of cockroach on the basis of external
morphology.
Short Answer Questions-I (3 marks each)
11. Differentiate between skeletal and smooth muscles.
12. Differentiate between male and female cockroach on the basis of external
morphology.
13. (a) What is open circulatory system ?
(b) Explain the respiratory system of cockroach.
14. (a) Give the common name of Periplaneta americana.
(b) How many spermathecae found in cockroach ?
(c) What is the position of ovaries in cockroach ?
(d) How many segments are present in the abdomen of cockroach ?
(e) Where do you find malpighian tubules ?
(f) What is mosaic vision ?
Long Answer Questions (5 marks each)
15. (a) What is compound epithelium ? What are their main function ?
(b) Where do we find areolar tissue ?
(c) How is adhering junction different from gap junction ?ANSWERS
Very Short Answers (1 mark)
1. Mammalian bone.
2. Excitability and conductivity.
3. Adipocytes.
4. Blood platelets.
5. Glands which discharge their secretions into ducts.
Short Answers-II (2 marks)
6. Refer ‘Points to Remember’.
7. White and yellow fibres. White fibres are thin, wavy, unbranched, inelastic,
occur in bundles and formed of protein collagen. Yellow fibres are thick,
straight, elastic, branched, occuring singly, formed of protein elastin.
8. (a) Bone tissue (b) Cartilage
(c) Neural tissue (d) Cardiac muscle
9. Refer ‘Points to Remember’.
10. Three pairs of legs and 2 pairs of wings.
Short Answers-I (3 marks)
11. Refer ‘Points to Remember’.
12. Refer ‘Points to Remember’.
13. Refer ‘Points to Remember’.
14. (a) American coackroach.
(b) One pair, present in 6th segment.
(c) Between 2nd and 6th abdominal terga.
(d) 10 segments.
(e) At the beginning of ileum in cockroach.
(f) Vision where several images of an object are formed by compound eye.
Helps detect movement of objects very efficiently.
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