Learning Objectives Order the levels of organization for living organisms. Key Points Cells are the most basic unit of life at the smallest level of organization. Cells can be prokaryotic without nucleus or eukaroyotic with nucleus.
The four categories of tissues are connective, muscles, epithelial, and nervous tissues. Organs are made of different types of tissues and perform complex functions. They can be hollow or solid. Organ systems are groups of organs that perform similar functions or perform functions together.
Many physiological functions are carried out by multiple organ systems working in tandem. Key Terms cell : The smallest unit of life capable of independent reproduction. Generally contains nucleic acid, cytoplasm, a cell membrane, and many other proteins and structures. Tissues : A group of similar cells with the same origin that work together to perform the same function.
Level 1: Cells The first and most basic level of organization is the cellular level. Level 2: Tissues Tissues are a group of similar cells of the same origin that carry out a specific function together. Level 3: Organs An organ is a structure made up of different tissues that perform specific bodily functions. Level 4: Organ Systems An organ system is a collection of organs that that work together to perform a similar function.
Authored by : Boundless. Provided by : Boundless. This cell is in anaphase of mitosis. You developed from a single fertilized egg cell into the complex organism containing trillions of cells that you see when you look in a mirror. During this developmental process, early, undifferentiated cells differentiate and become specialized in their structure and function. These different cell types form specialized tissues that work in concert to perform all of the functions necessary for the living organism.
Cellular and developmental biologists study how the continued division of a single cell leads to such complexity and differentiation. Consider the difference between a structural cell in the skin and a nerve cell.
A structural skin cell may be shaped like a flat plate squamous and live only for a short time before it is shed and replaced. Packed tightly into rows and sheets, the squamous skin cells provide a protective barrier for the cells and tissues that lie beneath.
A nerve cell, on the other hand, may be shaped something like a star, sending out long processes up to a meter in length and may live for the entire lifetime of the organism.
With their long winding appendages, nerve cells can communicate with one another and with other types of body cells and send rapid signals that inform the organism about its environment and allow it to interact with that environment. These differences illustrate one very important theme that is consistent at all organizational levels of biology: the form of a structure is optimally suited to perform particular functions assigned to that structure.
This number is a marker of inflammation. Basal Metabolic Rate: The number of calories metabolized at rest during a hour period. This number interpreted alongside your activity level, can be used to determine what is an appropriate amount of food for YOUR body. What do I need to do to prepare for my BIA? Avoid alcohol for 24 hours prior to the test. Avoid exercise and caffeine 4 hours before the test Drink glasses of water 2 hours before your test.
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