in this video we're going to look at the different levels of organization within a multicellular organism like a human so we'll cover the relationships between organelles cells tissues organs organ systems and finally organisms let's start with organelles which are also called subcellular structures these are the parts that make up a cell like the nucleus ribosomes and mitochondria each individual organelle has a specific role to play and when combined multiple organelles will form a single cell cells themselves come in all sorts of shapes and sizes and contain different combinations and numbers of the organelles that we just mentioned we call the different types of cells specialized cells and they include things like epithelial cells muscle cells and different types of glandular cells next up we have tissues which we can describe as a group of similar cells that work together to carry out a particular function for example lots of epithelial cells would form epithelial tissue which together have the function of covering the body's surfaces like our skin or the inside of our intestines meanwhile a lot of muscle cells would form muscle tissue which has the function of contracting and relaxing to move different parts of our body and lots of glandular cells would work together to form a glandular tissue which has the role of making and secreting chemicals like enzymes and hormones the next level is the organ and the definition of an organ is a group of different tissues that work together to perform a particular function so as you can see the definition is pretty much the same as the one for a tissue except instead of a group of similar cells it's a group of different tissues so epithelial tissue muscular tissue and glandular tissue may all work together to form an organ like the stomach which in this case has the particular function of killing microorganisms and breaking down proteins meanwhile different combinations of tissues might form other organs like the pancreas or the liver next we have the organ system which is just a group of organs that work together to perform a particular function for example the stomach pancreas and liver taken together with lots of other organs form the digestive system which has the role of digesting the food that we eat and absorbing nutrients other organ systems include the cardiovascular system and the reproductive system finally you could also think of the whole organism as being the highest level with multiple organ systems working together to form the organism one last thing i want to add before we finish is that we've only mentioned a few examples for each level in reality there are loads of types of each for example other organs include the skin teeth lungs spleen bones testes and dozens more and there are about 12 different organ systems including the immune system nervous system respiratory system endocrine system and urinary system hey everyone amadeus here i just wanted to let you know that we also have a learning platform where you can watch all of our videos practice what you've learned with questions and keep track of all of your progress for both the sciences and maths it's completely free so if you haven't already you can check it out by clicking on our logo here on the right or if you'd like to do the lesson for this particular video we put the link to that in the description down below we've also arranged all the videos for this subject in a playlist for you here that's all though so hope you enjoy and i'll see you next time thanks