CLASS 11TH BIOLOGY CHAPTER- 7 STRUCTURAL ORGANIZATION IN ANIMALS NCERT QUICK REVISION NOTES FOR NEET AND CBSE EXAM
STRUCTURAL ORGANIZATION IN ANIMALS
Three Types of Cell junctions
1. Tight junctions: Plasma membranes of adjacent cells are fused at intervals. They help to stop substances from leaking across a tissue.
2. Adhering junctions: Perform cementing function to keep neighbouring cells together.
3. 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 soometimes big molecules.
Types of Fundamental Animal Tissues
1. Epithelial Tissues
• Location
Free Surfaces.
• Functions
Protection, Secretion, Excretion, absorption, Sensory and reproduction.
2. Connective Tissues
• Location
Inside body, its organs other tissues and below skin.
• Functions
Holding or binding, support, transport and circulation, protection and storage.
3. Muscular Tissues
• Location
Inside movable parts
• Functions
Movements and locomotion
4. Nervous tissues
• location
Central Peripheral and every organ
• Functions
Communication and control
ANIMAL TISSUES
(i) Epithelial
(ii) Connective
(iii) Muscular
(iv) Neural
EPITHELIA 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 lining of stomach and intenstine.
4. Ciliated
• columnar or cubolidal 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
(i) Exocrine glands
• secrete mucus, saliva,oil, milk digestive enzymes.
• products released through ducts.
(ii) Endocrine glands
• secrete hormones.
• secrete directly into the fluid bathing the gland.
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) Adipose 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 TISSUES:
(i) Cartilage : made up of chondrocytes and collagen fibres; inter cellular material is solid and resists compression. Present in tip of nose outer ear joints, etc.
(ii) Bones: Ground substance is rich in calcium salts and collagen fibres Osteocyt es are present in launae. Bones support and protect softer tissues and organs. They interact with skeletal muscles to bring about movements. Bone marrow in some bones is the site of blood cell formation.
(iii) Blood: Fluid coonective tissue, consists of plasma and blood cells.
Muscular Tissues (long, contractile cells called fibres, bring about movement and locomotion)
(i) Skeletal Muscle
• Striated.
• Closely attached to sekeletal bones.
• long cylindrical multinucleated fibres.
(ii) Smooth Muscle
• Non-striated.
• Forms wall of Internal Organs like blood vessels stomach, intestine.
• Spindle like uninucleated fibres.
(iii) Cordiac Muscle
• Striated withintercalated disc for communication.
• Occurs in heart wall.
• Short cyclindrical uninucleated fibres.
NEURAL TISSUES:
• Neurons are the functional unit and are excitable cells.
• Neurogila cells make up more than half the volume of neural tissue. They protect and support neurons.
Cockroach-Periplaneta americana (Phylum-Arthropoda, Class-Insecta) Cockroach is a terrestrial, nocturnal, ominivorous,unisexual, oviparous insect Body convered by a chitinous, hard exoskeleton of hard plates called sclerities.
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), hypharynx (acts as tongue).
Thorax: 3 segments; prothorax, measothorax and metathorax.
Bears 2 pairs of wings
Forewings: tegmina (mesothoracic).
Hindwings: transparent, membranous (metathoracic)
3 pairs of legs in thoracic segments. (one pair in each thoracic segment.)
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 7th segment is boat shaped.
Also has anus and genital aperture at the hind end. Genital aperture surrounded by external genitalia called gonapophysis or phallomere.
Male Cockroach:
1. abdomen klong and narrow.
2. All nine sterna visible.
3. Anal style present.
Female Cockroach:
1. Abdomen short and broad.
2. Sevensterna visible. (7th sternumfused with 8th and 9th sterna).
3. Anal style absent.
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 caecae (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 muscular tube and differentiated into funnel shaped chambers with ostia on either side. Blood from sinuses enters heart through ostia and is pumped anteriorly to sinuses again. Blood is colourless (haemolymph).
Repiratory system: Network of trachea which open through 10 pairs of spiracles. Spiracles regulated by sphincters. Oxygen delivered directly to cells.
Excretion and osmoregulation: by malpighian tubules; uricotelic (Uric acid as excretory proudct).
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 supraoesophageal ganglion. Each eye consists of 200 hexagonal ommatidia.
REPRODUCTIVE SYSTEM:
Male reproductive system: Pair of testes (4th-6th segments) → vas deferens→ ejaculatory duct → male gonophore.
Glands-Seminal vesicle (stores sperms), mushroom shaped gland (6th-7thsegment).
FEMALE REPRODUCTIVE SYSTEM:
A pair of ovaries (with 8 ovarian tubules) → Oviduct → Genital chamber. Sperms transferred through spermatophores female produces 9-10 Ootheca. Fertilised eggs encased in capsules called oothecae (contains 14-16 eggs on an average) development of P. americana paurometabolous incompleted 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).
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