cellular organisation

seven specialised cells

• neutrophils

• squamous epithelial cells

• Guard cells/stomata

• Erythrocytes

• Soerm cells

• Palisade cells

• Root hair cells

Neutrophils

• Very flexible shape and lobed nucleus allows them to squeeze through cell junctions/fenestrations

• Form pseudopodia (cytoplasmic projections)) that engulf microorganisms

• Large number of lysosomes to ingest and destroy cells

Squamous epithelial cells

• A single layer of flattened cells

• The layer of cells form a thin-cross section which is permeable, so reduces diffusion pathway

Guard cells/stomata

• Inner cell walls are thicker which allows the cell to bend when turgid

• Cytoplasm has lots of chloroplasts and mitochondria

• In light, they pump in ions (active transport) which lowers the water potential, so water moves in by osmosis and the stoma opens

Erythrocytes

• Biconcave shape allows them to fit through the narrow capillaries

• No nucleus or organelles so more space for oxygen

Sperm cells

• Male gamers as haploid cells (23)

• Contain enzymes in the acrosome (head) to digest the cell wall of the female egg

• Lots of mitochondria for energy

• Have a flagellum (tail) to swim to the egg

• Aerodynamic to swim to egg faster

Palisade cell

• Large number of chloroplasts to maximise the absorption of life for photosynthesis

• Tall and thin, allows light to penetrate deeper before encountering another cell wall

• Walls are thin so carbon dioxide can easily diffuse into the cell

Root hair cell

• Mini micro hairs increase SA so the rate of water uptake by osmosis is greater (absorption)

• Thinner walls so water and mineral ions can move through more easy (short diffusion path)

• Mitochondria for active transport

Tissue

A group of differentiated similar cells that have specialists functions

Organ

Collection of tissues that are adapted to carry out a particular function

Organ system

Each system has a number of organs to carry out the major function of the organisms

Main types of animal tissues

• Nervous tissue

• Epithelial tissues

• Muscle tissues

• Connective tissue

• Epidermis tissue

• Vascular tissue

Nervous tissue

Support the transmission of electrical impulses

Epithelial tissue

Cover body surfaces- internal and external

Muscle tissues

contract (shorten) to move

Connective tissue

Either to hold other tissues together or acts as a transport medium

Epidermis tissue

Adapted to cover plant surface

Vascular tissue

Adapted for transport of H₂O and mineral ions