User:Svrabaya/Cell physiology

Cell physiology is the biological study about the activities that take place in a cell to keep it alive. This includes, among animal cells, plant cells and microorganisms. The term "physiology" refers to all the normal functions that take place in a living organism. All of these activities in the cell could be counted as following ; nutrition, environmental response, cell growth, cell division, reproduction and differentiation. The differences among the animal cell, plant cell and microorganisms show the essential functional similarity even though those cells have different structures. Cell physiology In the context of human physiology, the term cell physiology often specifically applies to the physiology of membrane transport, neuron transmission, and (less frequently) muscle contraction. In general, these cover the digestion of food, circulation of blood, and contraction of muscles and, therefore, are important aspects of human physiology. For a more complete description of the general physiological function of human cells (as well as the cells of other life forms), see the article on cell biology.

Experimental approach in cell physiology is an important aspect in cell physiology because it utilizes the experimental methods in order to solve any scientific issue related to physiology. the following examples have been studied in cellular problems by using the experimental method: First, the key of understanding cells' activities in animal, plant cells and microorganisms was studied by identified the nature of organization of cells. Second, the differences of the environment plays a role of the nature of the cell environment, cell resistance and the adjustment. Third, the nature of the cell in regulating and transporting materials into and out the cells crossing the cell membrane. Fourth, Cell foods and its inter-conversions and the mechanism of respiration process to release energy from cell's food. Fifth, the use of energy in respiration in terms of performing the variety types of work. For example, maintenance, readiness, osmotic and for manufacturing of secretions.

The relation of cell physiology to different fields of physiology such as, animal physiology, comparative animal physiology, plant physiology and molecular biology are being fundamental parts of physiology field. Animal physiology plays a role of the work of various organs of the body which those organs coordinate to integrate the animal behavior. medical men in were concerned about vertebrate organ physiology precisely with mammals, because the information provided could be beneficially applied to the physiology of human in health and diseases. it is a beneficial to work on organ physiology as a medical approach. However, the Cellular level can be used as well. In addition, Comparative animal physiology is a part of studying the function of any organ in various types of animals such as, vertebrate and invertebrate to find the fundamental relations. Plant physiology is more likely concerns about the response, nutrition, growth and reproduction of different types of plants. and Since the functioning of the animal and plant depend on the function of the cells component. All of these physiological studies have been recognized by researchers whom were interested in organisms and worked at the cellular level to solve problems at the organs levels. on the other hand, Molecular biology turns to explain the cells activities in at the molecular level.In the past time, it has been limited in studying activities of viruses and bacteria. However, now it is being extended on studying the activities of the Eukaryota cells. Molecular biology has been contributed as an aim for cell physiology by being as powerful source of mutants (this method has been applied to many issues in cell physiology) such as, transportation across the cell membrane and the nature of the membranes. However, many of the cell physiology problems have not been solved by the molecular approach. Cell physiology

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General Characteristics of Cell Phyisology

There are two types of cells: Prokaryotes and Eukaryotes.

Prokaryotes first came into existence and contain no self-contained nucleus, therefore making their mechanisms much simpler compared to the later-evolved Eukaryotes, which do contain a nucleus enveloping the cell's DNA and nuclear organelles.

Prokaryotes

Prokaryotes have DNA located in an area called the nucleoid, which is not membrane-bound. There are 2 domains of prokaryotes, which are bacteria and archaea. Unlike eukaryotes, prokaryotes do not have as much organelles. Some similarities between prokaryotic and eukaryotic structures is that both have plasma membranes and ribosomes. Some unique differences in prokaryotic structure is the presence of fimbriae and flagella. Fimbriae are finger-like projections that are on the surface of the cell and flagella are threadlike structures that aid in locomotion.

Eukaryotes Eukaryotes have a nucleus where DNA is contained. They are usually larger than prokaryotes and contain much more organelles. For example, the nucleus contains the nuclear envelope, nucleolus, and chromatin. In the cytoplasm, is the endoplasmic reticulum (ER), which is where membrane synthesis and other metabolic activities. There are two types, rough ER and smooth ER. Rough ER contains ribosomes and smooth ER lack ribosomes. Ribosomes are structures that synthesize proteins that float free in the cytoplasm or attach to the rough ER. The Golgi Apparatus consists of multiple membraneous sacs that is responsible for manufacturing and shipping out materials such as proteins. Lysosomes are structures that consists of enzymes that are used to break down substances. It is carried out through the process of phagocytosis, which consists of endocytosis and exocytosis. The mitochondria is the site where metabolic processes such as cellular respiration occurs. The cytoskeleton is made up of fibers that support the structure of the cell and plays an important role in the movement of the cell. Cell physiology

Physiological process

Movement of proteins

Pathway of proteins in cells start at endoplasmic reticulum (ER). Lipids and proteins are synthesized in the ER and carbohydrates are added in order to make glycoproteins. Glycoproteins undergo further synthesis in the Golgi apparatus which become glycolipids. Both glycoproteins and glycol lipids are then transported into the vesicles to the plasma membrane. The cell released secretory proteins known as exocytosis.

Transport of Ions

Ions travel across cell membranes through either channels, pumps, and transporters. Ions in channels move down an electrochemical gradient to produce electrical signals, while transporter use more than one gradient to produce these electrical signals. Pumps help maintain electrochemical gradients. The main type of pump is the Na/K pump. The pump helps move 3 Na+ ion out of the cell and two K+ ions into the cell. The entire process converts one ATP molecule to ADP and Pi.

Endocytosis in Animal Cells

Endocytosis is a form of active transport where a cell takes in molecules through the use of the plasma membrane and packaging them into vesicles.

Phagocytosis A cell surrounds particles, including food particles via extensions of the pseudopods which are located on the plasma membrane. These pseudopods then package these particles in a food vacuole. An organelle called a lysosome that contains hydrolytic enzymes will fuse with the food vacuole. The hydrolytic enzymes also known as digestive enzymes will then digest the particles within the food vacuole.

Pinocytosis

A cell takes in or “gulps” extracellular fluid into vesicles which are formed when the plasma membrane surrounds the fluid. The cell takes in the molecules which are found in the droplets. The cell can take in any molecules or solutes through this process.

Receptor-mediated endocytosis A form of pinocytosis where the cell takes in more specific molecules or solute. There are proteins with receptor sites located on the plasma membrane which bind to specific solutes. The receptor protein that are attached to the specific solutes go inside coated pits which then forms a vesicle. The vesicles now surround the receptors that are attached to specific solutes. The molecules are then released from the vesicles and receptor proteins are recycled back to the plasma membrane by the same vesicle.