University:
High School
Course:
High School Biology
Academic year:

2022
Views:

295

Pages:

5
Author:

Beriottooiix

11/8/2017 Hair definitions: Characteristics of Hair Hair is made of a tough protein called keratin. bsapp.com Anatomy of a Hair bsapp.com Follicle • The sheath of cells and connective tissue that surrounds the root of a hair • Hair is an appendage of the skin that grows out of a hair follicle. bsapp.com bsapp.com The follicle contains more than enough cells for simple DNA analysis bsapp.com 1 11/8/2017 Root Cuticle • The part of a hair that is embedded in a hair follicle. • The cuticle is the outside covering of the hair. • It is formed by overlapping scales that always point toward the tip of the hair. • A single root contains sufficient DNA for analysis bsapp.com bsapp.com Cortex Cuticle (cont.) •These scales are formed from special cells that are hardened and flattened while progressing from the follicle. bsapp.com Pigment granules are absent in grey hairs • the interior of the hair • embedded with pigment granules that impart color to hair • pigment granules are absent in grey hairs bsapp.com Medulla • a collection of cells which appears as a canal running though the center of the hair • the medulla is the most predominant hair feature in many species bsapp.com bsapp.com 2 11/8/2017 Types of Medulla Continuous-Interrupted-Fragmented Medulla: . bsapp.com Serial medulla is the term used to a describe multiple medulla within a single hair bsapp.com Medullary Index The percentage or fraction of the hair’s width occupied by the medulla [between 0 and 1] Hint: This is a math problem! bsapp.com Medulla ID using a microscope 3 11/8/2017 How did that hair get here? B A C 1. Naturally shed hair – club-shaped root 2. Burned hair D 3. Forcibly removed – tissue remaining 4. Forcibly removed – damaged root Comparison by Race: European (Caucasian) Appearance – generally straight or wavy Pigment granules: small and evenly distributed Details: color may be blonde, black, red or brown African: Appearance: kinky, curled or coiled Pigment granules: densely distributed, clumped, may differ in size and shape Asian: Appearance: straight Pigment granules: densely distributed Details: shaft tends to be coarse and straight, thick cuticle, continuous medulla Differences by cross section Differences by follicle type 4 11/8/2017 Follicle Variations by race 5