Noise-induced hearing lossNoise-induced hearing loss (NIHL) is a hearing impairment resulting from exposure to loud sound. People may have a loss of perception of a narrow range of frequencies or impaired perception of sound including sensitivity to sound or ringing in the ears. When exposure to hazards such as noise occur at work and is associated with hearing loss, it is referred to as occupational hearing loss. Hearing may deteriorate gradually from chronic and repeated noise exposure (such as to loud music or background noise) or suddenly from exposure to impulse noise, which is a short high intensity noise (such as a gunshot or airhorn).
ThyroidThe thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the isthmus (: isthmi). The thyroid gland is a butterfly-shaped gland located in the neck below the Adam's apple. Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid.
Non scarring hair lossNon scarring hair loss, also known as noncicatricial alopecia is the loss of hair without any scarring being present. There is typically little inflammation and irritation, but hair loss is significant. This is in contrast to scarring hair loss during which hair follicles are replaced with scar tissue as a result of inflammation. Hair loss may be spread throughout the scalp (diffuse) or at certain spots (focal). The loss may be sudden or gradual with accompanying stress.
Cellular differentiationCellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover.
PubertyPuberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a boy. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed.
TestosteroneTestosterone is the primary male sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair. It is associated with increased sex drive, the inclination to impress partners and other courting behaviors.
Enzyme-linked receptorAn enzyme-linked receptor, also known as a catalytic receptor, is a transmembrane receptor, where the binding of an extracellular ligand causes enzymatic activity on the intracellular side. Hence a catalytic receptor is an integral membrane protein possessing both catalytic, and receptor functions. They have two important domains, an extra-cellular ligand binding domain and an intracellular domain, which has a catalytic function; and a single transmembrane helix.
Juxtacrine signallingIn biology, juxtacrine signalling (or contact-dependent signalling) is a type of cell–cell or cell–extracellular matrix signalling in multicellular organisms that requires close contact. In this type of signalling, a ligand on one surface binds to a receptor on another adjacent surface. Hence, this stands in contrast to releasing a signaling molecule by diffusion into extracellular space, the use of long-range conduits like membrane nanotubes and cytonemes (akin to 'bridges') or the use of extracellular vesicles like exosomes or microvesicles (akin to 'boats').
Human embryonic developmentHuman embryonic development, or human embryogenesis, is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell (ovum).
Transmembrane proteinA transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently undergo significant conformational changes to move a substance through the membrane. They are usually highly hydrophobic and aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them (beta-barrels) can be also extracted using denaturing agents.
