INTEGUMENTARY SYSTEM Exercise # 8 Page#73

Competency 3: The Integumentary System Upon successful completion of this laboratory, the students should be able to recognize the various skin components of the integumentary system by: Recognizing, from prepared slides, selected skin tissues and structures. Explaining the structures and functions of epidermal and dermal layers of skin.  Identifying the major parts of the hair.

INTEGUMENTARY SYSTEM (Martini, chapter 5) LAYERS OF THE SKIN FROM EXTERNAL TO INTERNAL: 1- EPIDERMIS 2- DERMIS 3- HYPODERMIS

ALFONSO A. PINO MD.

EPIDERMIS Stratum corneum Function- protection from chemical, physical & biological agents 5 stratum (from external to internal) Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum germinativum (basale)

Stratum corneum- 15-30 layers of keratinized cells. Water resistant F- allows insensible perspiration More or less 500 ml of water every day Stratum lucidum- clear layer only in thick skin (palms & soles). F-contains flattered & packed cells filled with the protein keratin Stratum granulosum- grainy layer F- to produce protein keratin & keratohyalin basic structural component of hair & nails Stratum spinosum (8 to 10 layers) F- it contains Langerhands cells for Immune response against microorganisms & Cancer cells Stratum germinativum or basale (The innermost) F- cells divide to replace superficial cells it contains Melanocytes –to produce melanin For protection against uv radiation

Epidermis (5 stratums) ALFONSO A. PINO MD.

DERMIS Function- thermoregulation & protection 2 mayor components- papillary & reticular layers Papillary - contains capillary & lymphatic vessels & sensory neurons function- support & nourishment of the overlaying epidermis Reticular - deep to papillary layer function- to resist tension in the skin

HYPODERMIS FUNCTION- ENERGY STORE CUSHIONING INSULATION

ACCESSORY STRUCTURES Meissner’s corpuscles (white in models) F- light touch & tactile receptors Pacinian corpuscles (olive in models) F- deep pressure & vibration receptors Sebaceous glands- discharges waxy sebum into the hair follicle F- lubrication Hair: for protection, insulation, and tactile reception. It is divided into: Shaft: exposed hair and first part under skin Root- surrounded by hair follicle. Contains hair papilla- at the base Hair bulb- surrounds the papilla Arrector pili- smooth muscle that erects the hair Sweat glands- Apocrine Merocrine

Sebaceous Glands and Sweat Glands Exocrine Glands in Skin Sebaceous glands (oil glands) Holocrine glands Secrete sebum Sweat glands Two types: apocrine glands and merocrine (eccrine) glands Merocrine – products are secreted by exocytosis (e.g., pancreas, sweat, and salivary glands) Apocrine-- producing a fluid secretion by pinching off one end of the secretory cell while leaving the rest intact. Holocrine – products are secreted by the rupture of gland cells (e.g., sebaceous glands) Watery secretions Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Hair follicle ALFONSO A. PINO MD.

Hair follicle ALFONSO A. PINO MD.

Nails Nails protect fingers and toes Made of dead cells packed with keratin Metabolic disorders can change nail structure Nail production Occurs in a deep epidermal fold near the bone called the nail root

Copyright © 2009 Pearson Education, Inc Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Nails Structure of a Nail Nail body The visible portion of the nail Covers the nail bed Lunula The pale crescent at the base of the nail Sides of nails Lie in lateral nail grooves Surrounded by lateral nail folds Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Nails Structure of a Nail Skin beneath the distal free edge of the nail Is the hyponychium (onyx = nail) Visible nail emerges From the eponychium (cuticle) At the tip of the proximal nail fold Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

REMEMBER, GO TO THE TUTORING ROOM AND PRACTICE WITH MODELS!