Hair Shaft
Hair Shaft - Related Videos
01:22
Hair Cells
0 Views •
2019
Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here. Hair cells are named after...
08:38
Extraction and Analysis of Cortisol from Human and Monkey Hair
0 Views •
Cited by 199 •
2014
Cortisol (CORT) accumulates in the growing hair shaft of humans and nonhuman primates. We describe methods for extracting and analyzing hair CORT with high precision and sensitivity. Measurement of hair CORT is particularly well-suited for assessing chronic stress over periods of weeks to months.
01:18
Stresses in a Shaft
0 Views •
2024
The shaft PQ is subjected to a twisting force when equal and opposite torques are applied on either side. A section that cuts perpendicular to the shaft's axis at any arbitrary point R is examined to understand this. When the free-body diagram of the QR segment is analyzed, it reveals the shearing forces exerted by the PR portion onto the QR segment as the shaft experiences twisting. Applying equilibrium conditions to the QR segment establishes that the internal shearing forces within the...
05:28
Targeted Expression of GFP in the Hair Follicle Using Ex Vivo Viral Transduction
0 Views •
Cited by 1 •
2008
The hair follicle is a highly complex appendage of the skin containing a multiplicity of cell types. The follicle undergoes constant cycling through the life of the organism including growth and resorption with growth dependent on specific stem cells. The targeting of the follicle by genes and stem cells to change its properties, in particular, the nature of the hair shaft is, discussed. Hair follicle delivery systems are described, such as liposomes and viral vectors for gene therapy. The...
01:16
Design of Transmission Shafts
0 Views •
2024
The design of a transmission shaft is governed by two primary specifications: the power it transmits and its rotational speed. These parameters guide the selection of the shaft's material and cross-sectional dimensions, ensuring that the material's maximum shearing stress remains within the elastic limit while transmitting the desired power at the given speed. The system's power is intrinsically linked to the applied torque. The torque applied to the shaft can be calculated by reconfiguring the...
FAQs
Each layer records a stage of cellular organization. Matrix cells accumulate keratin and lose their nuclei as they move upward, producing the outer cuticle, the cortex, and sometimes a medulla. Together, these compartments turn a population of proliferating follicle cells into a strong, lightweight fiber, linking visible architecture to follicle biology.
The medulla is present in many hairs but not all, so internal organization can vary among shafts. Its presence or absence distinguishes one aspect of shaft architecture, while the cuticle and cortex provide the other described compartments. This variation gives biological studies an additional structural feature to document when comparing hair samples.
Once matrix-derived cells have accumulated keratin and lost their nuclei, the exposed shaft no longer carries out active metabolism. Consequently, researchers interpret it as a keratinized product of follicular activity rather than as living tissue itself. This distinction helps frame studies of growth, pigmentation, damage, and disorders around what the follicle produced.
Researchers can examine shaft features as evidence of processes initiated in the follicle. Because the shaft reflects the biology of the structure that produced it, observations can support assessments of hair growth and pigmentation, alongside evaluations of damage or disorders. The approach connects an exposed fiber with events occurring deeper within the skin.
Hair shaft research has roles in dermatology, toxicology, forensic biology, and investigations of keratinized-tissue development. The relevant question differs by field: studies may focus on hair disorders, toxicology-related questions, biological investigations, or how cells become organized keratinized material. Thus, the same fiber can support both applied assessments and basic biology.
Damage and disorder studies use the shaft as a structural record of follicular and keratinization biology. Researchers can relate observed changes to the fiber’s organization into cuticle, cortex, and, when present, medulla, while also considering the growth and pigmentation questions the sample can address. This makes the shaft useful for connecting appearance with underlying biological processes.