Cell organisation

Cell organisation

Type of Cell & functions

Muscle cellsCell is able to contractProduces movement

NeuroneShape into a long thin fibreConducts nerve impulses

White blood cellChanges its shape Engulf & destroys microorganisms by phagocytosis

Red blood cellDisc shape, biconcave & without nucleusTransport o2

Cheek cell (lining epithelial cell)Flattened shape with interlocking edgesCells fits together forming a thin covering for protection

Palisade mesophyll cellCell contains many chloroplast and is columnarTo compact cells & maximize photosynthesis

XylemThe cell walls are deposited with lignin, with a channel through the centreThick cell walls to withstand pressure and give supportThe channel transport water

Phloem (tissue)Consists of continuous sieve tubes with companion cells Transport food

TISSUE

INTERNAL ENVIRONMENT

The meaning of internal environmentExternal environment: physical place where it lives in and where it interacts with other organismsTr.Rez@SB201316

Internal environment : environment inside the organisms, which is the fluid surrounding the cells

The meaning of internal environment

Tissue fluid/interstitial fluid:Fluid surrounding the cellsFills the narrow spaces between the cells, bathes the cells, & keeps the cells functioning normallyCells receive all their substances (nutrients & O2) from the blood stream through the tissue fluidTr.Rez@SB201317

Factors Affecting Internal EnvironmentFactors affecting the internal environment:Temperature (for human: 37c)pH value (for human: 7.4)Osmotic pressureGlucose level (for human : 90mg per 100 cm-3)

Tr.Rez@SB201319

Why maintain optimal temperature?In humans, the internal environment is maintained at 37C for optimal enzyme activityIf the temperature rises too highenzymes are denatured & lose their ability to functionIf the temperature falls too lowenzymes become inactive

Tr.Rez@SB201320

Why maintain optimal pH?pH of human tissue fluid is 7.4Enzymes function within narrow range oh pHIf the pH changes, enzymes will be denatured and lose the ability to functionTr.Rez@SB201321

Functions of the cells depends on their internal environment which are to:Provide the cells with substances like nutrients, O2 & glucoseRemove metabolic waste products from cellsProvide an optimal temperature and pH balance for the enzyme to function properlyProvide optimal osmotic pressure & glucose level for cells to function accurately Tr.Rez@SB201322