07Class 11 Biology
Structural Organisation in Animals short notes
Short notes on the four animal tissue types and the organ systems of the frog.
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Epithelial tissue
- Squamous: flat cells, as in blood vessels and air sacs.
- Cuboidal: in kidney tubules and gland ducts.
- Columnar: in the stomach and intestine lining, and it may have microvilli.
- Ciliated: moves mucus along, as in bronchioles and fallopian tubes.
- Cell junctions: tight junctions stop leaks, adhering junctions hold cells together, and gap junctions connect cells.
Connective tissue
- Loose: areolar and adipose tissue.
- Dense: tendons join muscle to bone, and ligaments join bone to bone.
- Specialised: cartilage, bone and blood.
- Bone has hard calcium salts and collagen, and cartilage has chondrocytes in lacunae.
Muscle and nerve
- Skeletal: striated, voluntary.
- Smooth: non-striated, involuntary, as in the gut wall.
- Cardiac: striated, involuntary, with intercalated discs.
- Neurons carry impulses, and neuroglia support them.
Frog
- Rana tigrina is the common Indian frog. It's ectothermic, with moist skin, and undergoes hibernation and aestivation.
- It breathes through skin in water, and also through lungs and the mouth lining on land.
- The heart has three chambers: two atria and one ventricle.
- Males have vocal sacs and copulatory pads. Fertilisation is external, and development goes through a tadpole stage.
Where students slip up
- Mixing up tendons and ligaments.
- Calling cardiac muscle voluntary because it's striated.
- Forgetting a frog's kidneys and sex ducts share a urinogenital tract in males.
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