B2.2 - Tissues, organs & organ systems

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  • Created by: Leyha M
  • Created on: 06-12-15 23:31

Tissues, organs & systems

During development, cells differentiate-- they become specialised so they can perform different functions.

CELL - the biological unit of all organisms

TISSUE - a group of specialised cells all carrying out the same function

ORGAN - a group of different tissues working together to carry out a particular function

ORGAN SYSTEM - a group of organs working together to caarry out a particular function

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Animal organs I


MUSCULAR TISSUE - contract to bring about movement

GLANDULAR TISSUE - produces substances such as enzymes + hormones

EPITHELIAL TISSUE - covers some parts of the body

Organs are made of tissues& can contain many tissues,

The stomach contains:

Muscular tissue --> to churn food + digestive juices

Glandular tissue --> produces digestive juices

Epithelial tissue --> covers inside+outside of stomach

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Animal organs II

LIVER - produces bile which neutralises acid to create alkali conditions // emulsifies fat droplets to increase surface area, easier for enzymes to surround fat, so faster digestion

LARGE INTESTINE - water absorbed from undigested food into bloodstream, forming faeces

SALIVARY GLAND - produces enzymes

PANCREAS - produces enzymes for small intestine

GALL BLADDER - stores biles + releases it into small intestine

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Animal organs III

STOMACH - produces enzymes // hydrochloric acid, kills harmful bacteria // mucus, creates barrier between acid+enzymes so stomach lining isn't broken down

SMALL INTESTINE - produces enzymes // soluble food molecules absorbed by diffusion into bloodstream, gets transported around body // large surface area, faster diffusion

OESOPHAGUS - peristalsis, squeezes food down to the stomach

ANUS - faeces pass out of body

RECTUM - stores faeces

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Plant organs I

3 organs all plants have:: stem / root / leaves


Epidermal - covers + protects plants. May be transparent enough to allow sunlight through

Mesophyll -a layer of cells where photosynthesis occurs

Xylem&phloem - involved in transporting subtances around plant

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Plant organs II

LEAF FUNCTIONS:                                                                                                                       STOMATA - a tiny hole, allows gases to move in and out. (Takes in co2 for photosynthesis).

WAXY CUTICLE - prevents water loss

AIR SPACESallows room for gas

SPONGY LAYER - large surface area for gas exchange

PALISADE -  layer of cells, close to light, packed together, full of chloroplasts

CHLOROPLAST - stacks of membranes&chlorophyll, give an increased surface area for photosynthesis

UPPER EPIDERIS - is upper leaf surface, has NO chloroplasts; protective layer, is clear to allow light through

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