Pruritus ani

S Siddiqi1, V Vijay, M Ward

  • 1Department of General Surgery, University College Hospital, London, UK. shahab@doctors.org.uk

Abstract

Related Concept Videos

Accessory Structures of the Skin: Hair and Hair Follicles01:16

Accessory Structures of the Skin: Hair and Hair Follicles

Hair and hair follicles are integral components of the integumentary system. Hair is a filamentous structure composed mainly of a protein called keratin. It is found on the surface of the skin throughout the body, except for areas such as the palms of the hands and soles of the feet.
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Hair strands originate at the epidermal penetration called the hair follicle. The hair shaft is the part...
Nomenclature of Aryl and Heterocyclic Amines01:10

Nomenclature of Aryl and Heterocyclic Amines

The simplest aromatic amine is phenylamine, which contains an –NH2 functionality directly attached to an aromatic ring. The name aniline is designated for this skeleton. As shown in Figure 1, the common names of the functionalized anilines involve prefixes ortho-, meta-, and para- to indicate the substitution position. Different functionalized aniline derivatives also have notable trivial names.
Physical Properties of Amines01:26

Physical Properties of Amines

Amines with low molecular weight are usually gaseous at room temperature, while those with high molecular weight are liquid or solids in nature. Usually, low molecular weight amines have a rotten fish-like smell. Diamines typically have a pungent smell. For instance, cadaverine and putrescine, depicted in Figure 1, are two molecules responsible for decaying tissue.
Anthelminthic Agents01:15

Anthelminthic Agents

Anthelmintic drugs differ significantly from antiparasitic therapies targeting protozoa, primarily due to differences in parasite biology. Whereas most protozoal treatments act on proliferating cells, anthelmintics are typically directed against mature, nonproliferative helminths. The therapeutic approach considers the helminth's reliance on neuromuscular coordination, glucose metabolism, and microtubular integrity for survival, reproduction, and localization within the host. Most anthelmintics...
Basicity of Aromatic Amines01:18

Basicity of Aromatic Amines

The basicity of aromatic amines is much weaker than that of aliphatic amines due to the involvement of the lone pair of electrons over the N atom in resonance with the aryl rings. Generally, the electron-donating ability of any substituents on the aryl ring of aromatic amines increases the basicity of the amine by increasing electron density, and hence the availability of lone pair on the nitrogen. On the other hand, electron-withdrawing functional groups on the aryl ring of amines decrease the...
Introduction to the Integumentary System01:25

Introduction to the Integumentary System

The integumentary system is the organ system that comprises the skin and its associated structures. It is the largest system in the human body and plays a crucial role in protecting and maintaining homeostasis. The integumentary system serves several functions including protection, regulation, sensation, and secretion.
The skin, which is the primary organ of the integumentary system, consists of three main layers: the epidermis, dermis, and hypodermis (subcutaneous tissue). The epidermis is the...