Mindblown: a blog about philosophy.
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Nucleus and Nucleolus
The nucleus, formed by a nuclear membrane around a fluid nucleoplasm, is the control center of the cell. Threads of chromatin in the nucleus contain deoxyribonucleic acid (DNA), the genetic material of the cell. The nucleolus is a dense region of ribonucleic acid (RNA) in the nucleus and is the site of ribosome formation. The nucleus determines how the cell will function, as well as the basic structure of that cell.
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Cell Membrane
Every cell in the body is enclosed by a cell (Plasma) membrane. The cell membrane separates the material outside the cell, extracellular, from the material inside the cell, intracellular. It maintains the integrity of a cell and controls passage of materials into and out of the cell. All materials within a cell must have access to the…
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Cell Structure
Ideas about cell structure have changed considerably over the years. Early biologists saw cells as simple membranous sacs containing fluid and a few floating particles. Today’s biologists know that cells are infinitely more complex than this. There are many different types, sizes, and shapes of cells in the body. For descriptive purposes, the concept of a “generalized…
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Cell Structure And Function
Cells, the smallest structures capable of maintaining life and reproducing, compose all living things, from single-celled plants to multibillion-celled animals. The human body, which is made up of numerous cells, begins as a single, newly fertilized cell. Almost all human cells are microscopic in size. To give you an idea how small a cell is, one average-sized adult…
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Introduction
This section provides detailed information about cell structure and function, four basic types of tissue in the human body, and the different types of membranes found in the body.
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Review
Here is what we have learned from Introduction to the Human Body: The human body is a single structure but it is made up of billions of smaller structures of four major kinds: cells, tissues, organs, and systems. An organ is an organization of several different kinds of tissues so arranged that together they can perform…
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Body Cavities
The cavities, or spaces, of the body contain the internal organs, or viscera. The two main cavities are called the ventral and dorsal cavities. The ventral is the larger cavity and is subdivided into two parts (thoracic and abdominopelvic cavities) by the diaphragm, a dome-shaped respiratory muscle. Thoracic Cavity The upper ventral, thoracic, or chest cavity contains the heart, lungs, trachea, esophagus, large blood vessels, and nerves.…
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Planes of the Body
Coronal Plane (Frontal Plane) – A vertical plane running from side to side; divides the body or any of its parts into anterior and posterior portions. Sagittal Plane (Lateral Plane) – A vertical plane running from front to back; divides the body or any of its parts into right and left sides. Axial Plane (Transverse Plane) – A horizontal plane; divides the body…
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Directional Terms
Directional terms describe the positions of structures relative to other structures or locations in the body. Superior or cranial – toward the head end of the body; upper (example, the hand is part of the superior extremity). Inferior or caudal – away from the head; lower (example, the foot is part of the inferior extremity). Anterior or ventral – front (example, the kneecap is located on the anterior side…
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Anatomical Terminology
Before we get into the following learning units, which will provide more detailed discussion of topics on different human body systems, it is necessary to learn some useful terms for describing body structure. Knowing these terms will make it much easier for us to understand the content of the following learning units. Three groups of…
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