Multicelluar organisation Flashcards
What are the 3 factors that limit cell size?
Ratio of surface area to volume, rate of diffusion into the cell through the cytoplasm and concentration of reactants and catalysts
What happens as the size of the cell increases?
The SA:V ratio decreases so its harder for gases, waste and nutrients to diffuse in and out of
Why is there a limit to cell size?
Small cells can meet nutrient absorption and waste removal requirements by diffusion, which larger cells cant
What are the issues of being large/multicellular?
They are made up of many cells each with a high SA:V ratio but the overall organisms SA is too low for diffusion to be practical
What are solutions for multicellular?
Evolve high surface area exchange surfaces, evolve transport systems and evolve communication systems
What is an example of a high SA exchange surface?
Gills or lungs
What is an example of a transport system?
Blood supply or lymphatic system
What is an example of a communication system?
Hormones/ nerves to coordinate cell activities
What is a molecule?
It’s a building block of organelles, obtained from diet or manufactured in body
What is an organelle?
A sub-cellular compartment with a specific function
What is a cell?
A unit of living matter surrounded by plasma membrane
How can a cell be specialised?
Structurally or chemically
What is a tissue?
A group of specialised cells from a common origin with a similar structure and function
What is an organ?
A group of physically associated tissues working together to perform a major function efficiently
What is an organ system?
A group of organs and tissues working in co-ordination to perform a gross function
What are epithelial cells?
Sheets of cells that cover the surface of a body and line its internal cavities such as the lungs and intestine
What are the 4 types of epithelial cells?
Squamous, columnar, cuboidal and ciliated
What are squamous epithelial cells?
Thin and flat so fluid flows over easily
What are an example of squamous epithelial cells?
Skin, lining of blood vessels and lungs
What are columnar epithelial cells?
Tall thin and can secrete mucous
Where are columnar epithelial cells located?
Stomach and intestine lining
Where are cuboidal cells located?
Lining of glands and ducts
What are ciliated epithelial cells?
They beat rhythmically to move mucous and are easily damaged by smoke or pollution
Where are ciliated epithelial cells located?
Lining of air passages
