Histology Level 1 Semester 1 PDF

Histology lecture (14) Skin (2) Histology 1. Sweat glands. 2. Hair 3. Hair follicle. 4. Sebaceous glands. 5. Arrector pili ms. Deep in dermis or hypodermis. More numerous in thick skin than thin skin....

Histology lecture (14) Skin (2) Histology 1. Sweat glands. 2. Hair 3. Hair follicle. 4. Sebaceous glands. 5. Arrector pili ms. Deep in dermis or hypodermis. More numerous in thick skin than thin skin. Simple coiled tubular gland. 1. The secretory parts (acini) 2. The Excretory parts (ducts): Duct collects sweat secretion from the acini Duct ascends in a spiral course to Duct opens into hair follicle. epidermis It opens on the surface of skin. Histology Nearly all over the body Axilla, areola of the breast, pubic region, perianal region. Very numerous Less numerous. The secretory cells are intact after The apical part of the cytoplasm is secretion. detached during secretion(artifact) Secretion of the “sweat” secretion of a “characteristic sweat” after puberty under influence of sex hormones Narrow lumen Wide lumen Opens on skin surface Opens into hair follicle Histology Histology Shaft: projecting above skin surface. Root: embedded or implanted in the skin.  Polyhedral cells  Contains soft keratin.  Elongated cells  Contains hard keratin and melanin pigments which give the color of the hair.  Flat scales.  Contains hard keratin. The expanded lower end of the hair. It consists of “hair matrix” which is a cellular mass. Proliferation of the matrix cells results in growth of the hair in length. Histology It is a hole formed by an epidermal down-growth in which the root of the hair is present. The wall of the hair follicle is called “root sheath” which is divided into 3 types: It is identical with the malpighian layer of epidermis. It is a condensed part of C. T. of the dermis. Histology They open into the upper 1/3 of hair follicle at the obtuse angle between the follicle and the surface of the skin Holocrine i.e. the central cells disintegrate completely to secrete “sebum”. It is a sac-like structure. Formed of one or more alveoli which open into a common duct. Short, wide and opens into the upper 1/3 of hair follicle. Lined with stratified squamous epithelium. Histology It is a band of smooth muscle fibers touching the bottom of the sebaceous gland. Contraction of this muscle due to stress or emotion (as fear) leads to: 1. Erection of the hair shaft 2. Squeezing of sebaceous secretion into the duct. 3. Appearance of goose-skin.