In cell biology and pathophysiology, Cellular adaptation refers to changes made by a cell in response to adverse environmental changes. See also List of basic cell biology topics. Cell biology (also called cellular biology or formerly cytology, from the Pathophysiology is the study of the disturbance of normal Mechanical, Physical, and Biochemical functions either caused by a Disease, or resulting The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called [1] The adaptation may be physiologic(al) (normal) or pathologic(al) (abnormal). Five major types of adaptation include atrophy, hypertrophy, hyperplasia, dysplasia, and metaplasia. Atrophy is the partial or complete Wasting away of a part of the Body. Hypertrophy is the increase of the size of an organ or in a select area of the tissue Hyperplasia (or "hypergenesis" is a general term referring to the proliferation of cells within an organ or tissue beyond that which is ordinarily seen in e Dysplasia (from Greek roughly "bad formation" is a term used in Pathology to refer to an abnormality in maturation of cells within a tissue Metaplasia ( Greek: "change in form" is the reversible replacement of one differentiated Cell type with another mature differentiated cell type
Atrophy is a decrease in cell size. If enough cells in an organ atrophy the entire organ will decrease in size. Thymus atrophy during early human development (childhood) is an example of physiologic atrophy. In Human anatomy, the thymus is an organ located in the upper Anterior portion of the chest cavity just behind the Sternum. Human development is the process of Growing to maturity In biological terms this entails growth from a one-celled Zygote to an adult Human being Skeletal muscle atrophy is a common pathologic adaptation to skeletal muscle disuse (commonly called "disuse atrophy). Skeletal muscle is a type of Striated muscle, which usually attaches to tendons Tissue and organs especially susceptible to atrophy include skeletal muscle, cardiac muscle, secondary sex organs, and the brain. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain
Hypertrophy is an increase in cell size. If enough cells of an organ hypertrophy so will the whole organ. The heart and kidneys have increased susceptibility to hypertrophy. The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic The kidneys are complicated organs that have numerous biological roles Hypertrophy involves an increase in intracellular protein rather than cytosol (intracellular fluid). Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl The cytosol or intracellular fluid (or cytoplasmic matrix) is the liquid found inside cells. Hypertrophy may be caused by mechanical signals (e. g. , stretch) or trophic signals (e. Tropic hormones are Hormones that regulate the activity of various other Endocrine glands One example is the Thyroid-stimulating hormone (TSH (produced g. , growth factors). An example of physiologic hypertrophy is in skeletal muscle with sustained weight bearing exercise. In Orthopedics, weight bearing is the amount of Weight a patient puts on the leg on which surgery has been performed An example of pathologic atrophy is in cardiac muscle as a result of hypertension. Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the Blood pressure is chronically elevated
Hyperplasia is an increase in the number of cells. It is the result of increased cell mitosis, or division. Mitosis is the process in which a Eukaryotic cell separates the Chromosomes in its Cell nucleus, into two identical sets in two daughter nuclei The two types of physiologic hyperplasia are compensatory and hormonal. Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body Commpensatory hyperplasia permits tissue and organ regeneration. It is common in epithelial cells of the epidermis and intestine, liver hepatocytes, bone marrow cells, and fibroblasts. Epidermis is the outermost layer of the Skin. It forms the waterproof protective wrap over the body's surface and is made up of stratified squamous Epithelium with In Anatomy, the intestine is the segment of the alimentary canal extending from the Stomach to the Anus and in humans and other mammals consists The liver is a vital organ in the human body and is present in Vertebrates and some other animals Hepatocytes make up 70-80% of the Cytoplasmic mass of the Liver. Bone marrow is the flexible tissue found in the hollow interior of Bones In adults marrow in large bones produces new Blood cells It constitutes 4% of A fibroblast is a type of cell that synthesizes and maintains the Extracellular matrix of many Animal tissues It occurs to a lesser extent in bone, cartilage, and smooth muscle cells. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Cartilage is a type of dense Connective tissue. It is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix Smooth muscle is a type of non- Striated muscle, found within the Tunica media layer of large and small Arteries and Veins, the bladder Hormonal hyperplasia occurs mainly in organs that depend on estrogen. Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, For example, the estrogen-dependent uterine cells undergo hyperplasia and hypertrophy following pregnancy. Pathologic hyperplasia is an abnormal increase in cell division. A common pathologic hyperplasia in women occurs in the endometrium and is called endometriosis. The endometrium is the inner membrane of the Mammalian Uterus. Endometriosis (from endo, "inside" and metra, " Womb " is a common medical condition characterized by growth beyond or outside the uterus
Dysplasia refers generally to abnormal changes in cellular shape, size, and/or organization. Dysplasia is not considered a true adaptation; rather, it is thought to be related to hyperplasia and is sometimes called "atypical hyperplasia. " Tissues prone to dysplasia include cervical and respiratory epithelia. In Anatomy, ' cervical' is an Adjective that has two meanings of or pertaining to any Neck. In living organisms a respiratory system functions to allow Gas exchange. Dysplasia often occurs in the vicinity of cancerous cells, and it may be involved in the development of breast cancer. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled Breast cancer is a Cancer that starts in the cells of the Breast in women and men
Metaplasia occurs when a differentiated cell of a certain type is replaced by another cell type, which may be less differentiated. In Developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized Cell type. It is a reversible process thought to be caused by stem cell reprogramming. Stem cells are found in epithelia and embryonic mesenchyme of connective tissue. Stem cells are cells found in most if not all multi-cellular Organisms. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular Mesenchyme refers to loosely organized connective tissue present in the embryo regardless of origin Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, Muscle, and Nervous tissue) A prominent example of metaplasia involves the changes associated with the respiratory tract in response to inhalation of irritants, such as smog or smoke. The bronchial cells convert from mucus-secreting, ciliated, columnar epithelium to non-ciliated, squamous epithelium incapable of secreting mucus. The bronchioles or bronchioli are the first Airway branches that no longer contain Cartilage. In vertebrates mucus is a slippery secretion produced by and covering Mucous membranes It is a viscous Colloid containing Antiseptic enzymes (such as A cilium (plural cilia) is an Organelle found in eukaryotic cells Cilia are tail-like projections extending approximately In biology columnar refers to the shape of Epithelial cells that are taller than they are wide In Anatomy, squamous epithelium (from Latin squama, "scale" is an Epithelium characterised by its most superficial layer consisting These transformed cells may become dysplasic or cancerous if the stimulus (e. g. , cigarette smoking) is not removed.
References
- ^ Huether, S. E. & McCance, K. L. (2008). Understanding Pathophysiology, Ed 4, p. 62-65.