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‫تشريح المحاضرة االولى‬ Anatomy: is the study of structure Physiology:- is the study of function *These approaches are complementary and never entirely separable *they form the bedrock of the health sciences. Aristotle was one of the first philosophers to write about anatomy and physiology. He bel...

‫تشريح المحاضرة االولى‬ Anatomy: is the study of structure Physiology:- is the study of function *These approaches are complementary and never entirely separable *they form the bedrock of the health sciences. Aristotle was one of the first philosophers to write about anatomy and physiology. He believed that diseases and other natural events could have either supernatural causes, which he called theologi The organism:- is a single, complete individual. organ system:- is a group of organs with a unique collective function, such as circulation, respiration, or digestion. The human body has 11 organ systems An organ is a structure composed of two or more tissue types that work together to carry out a particular function. *The skin, for example, is the body’s largest organ. Included within it are thousands of smaller organs: Each hair, nail, gland, nerve, and blood vessel of the skin is an organ in itself A single organ can belong to two organ systems. For example, the pancreas belongs to both the endocrine and digestive systems. A tissue;- is a mass of similar cells and cell products that forms a discrete region of an organ and performs a specific function. The body is composed of only four primary classes of tissue: epithelial, connective, nervous, and muscular tissue. Cells:- are the smallest units of an organism that carry out all the basic functions of life *A cell is enclosed in a plasma membrane composed of lipids and proteins. Most cells have one nucleus, an organelle that contains its DNA Cytology:- the study of cells and organelles. Organelles are microscopic structures in a cell that carry out its individual functions. Examples include mitochondria, centrioles, and lysosomes. Organelles and other cellular components are composed of molecules. The largest molecules, such as proteins, fats, and DNA, are called macromolecules. A molecule is a particle composed of at least two atoms, the smallest particles with unique chemical identities. Cell Shapes and Sizes: There are about 200 kinds of cells in the human body Squamous: a thin, flat, scaly shape, often with a bulge where the nucleus is, much like the shape of a fried egg it found the surface layer (epidermis) of the skin. Cuboidal: squarish-looking in frontal sections and about equal in height and width; liver cells are a good example. Columnar: distinctly taller than wide, such as the inner lining cells of the stomach and intestines. Stellate: having multiple pointed processes projecting from the body of a cell, giving it a somewhat starlike shape. The cell bodies of many nerve cells are stellate Spheroidal to ovoid: round to oval, as in egg cells and white blood cells.  Discoid: disc-shaped, as in red blood cells. Fusiform: spindle-shaped; elongated, with a thick middle and tapered ends, as in smooth muscle cells. Fibrous: long, slender, and threadlike, as in skeletal muscle cells and the axons (nerve fibers) of nerve cells. Cytology: the scientific study of cells, was born in 1663 when Robert Hooke observed the empty cell walls of cork and coined the word cellulae (“little cells”) to describe them. The cell (from Latin cell, meaning "small room") is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life that can replicate independently, and cells are often called the "building blocks of life". The cells have the following major components: ▪ Plasma membrane ▪ Cytoplasm ▪ Cytoskeleton ▪ Organelles (including nucleus) ▪ Inclusions -Cytosol Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. The number of cells in plants and animals varies from species to species, humans contain more than 10 trillion cells. The primary components of the cell, and their function: Membrane: The cell membrane, or plasma membrane, is a biological membrane that surrounds the cytoplasm of a cell. In animals, the plasma membrane is the outer boundary of the cell. This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of phospholipids. Hence, the layer is called a phospholipid bilayer, or sometimes a fluid mosaic membrane. Embedded within this membrane is a variety of protein molecules that act as channels and pumps that move different molecules into and out of the cell. The Cytoskeleton: acts to organize and maintain the cell's shape; anchors organelles in place. The eukaryotic cytoskeleton is composed of microfilaments, intermediate filaments and microtubules Genetic Materials: Two different kinds of genetic material exist: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Cells use DNA for their long-term information storage. The biological information contained in an organism is encoded in its DNA sequence Organelles: Organelles are parts of the cell which are adapted and/or specialized for carrying out one or more vital functions, analogous to the organs of the human body (such as the heart, lung, and kidney, with each organ performing a different function). 1.Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes, and is the place where almost all DNA replication and RNA synthesis (transcription) occur. The nucleus is spherical and separated from the cytoplasm by a double membrane called the nuclear envelope. DNA is transcribed, or copied into a special RNA, called messenger RNA (mRNA). This mRNA is then transported out of the nucleus, where it is translated into a specific protein molecule. 2.Endoplasmic Reticulum: The endoplasmic reticulum (ER) is a transport network for molecules targeted for certain modifications and specific destinations, as compared to molecules that float freely in the cytoplasm. The ER has two forms: the rough ER(RER), which has ribosomes on its surface that secrete proteins into the ER, and the smooth ER, which lacks ribosomes. The smooth ER(SER) plays a role in calcium sequestration and release 3. Golgi apparatus: The primary function of the Golgi apparatus is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell.  4. Mitochondria: generate energy for the cell. Respiration occurs in the cell mitochondria, which generate the cell's energy by oxidative phosphorylation, using oxygen to release energy stored in cellular nutrients (typically pertaining to glucose) to generate ATP. 5. Lysosomes: Lysosomes contain digestive enzymes (acid hydrolases). They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. 6. Centrosome: the cytoskeleton organizer. Centrosomes are composed of two centrioles, which separate during cell division and help in the formation of the mitotic spindle. A single centrosome is present in the animal cells. 7. Vacuoles: Vacuoles sequester waste products. 8. Ribosomes: The ribosome is a large complex of RNA and protein molecules. They each consist of two subunits, where RNA from the nucleus is used to synthesise proteins from amino acids. Ribosomes can be found either floating freely or bound to a membrane (the rough endoplasmatic reticulum).