Ex 7: Itergumentary System

  1. epidermis
    • composed of thick keratinized stratified squamous epithelial cells, outermost protective shield of the body that consists of 4 cell types 
    • & 4 or 5 layers.
  2. dermis
    a tough leathery layer composed of fibrous connective tissue that makes up a bulk of the skin.

    vascularized nutrients reach the epidermis by diffusing through the tissue fluid. 

    regulation of body temp, hot(arterioles-dilate); cold (arterioles-constrict)
  3. hypodermis/ superficial fascia-
    (subcutaneous tissue) consist mostly adipose.
  4. name and describe the function of the 4 distinct cell types
    • 1. Keratinocytes — produces keratin* fibrils, which arises from stratum basale layer.
    • *(a fibrous protein that gives the epidermis its protective properties)

    2. Melanocytes — provide protection for the keratinocyte nucleus by forming a pigment shield (melanin granules) that protects the nucleus from the damaging effects of ultraviolet (UV) radiation in sunlight.

    — freckles due to a concentration of melanin in one spot.

    3. Langerhans’ cell (also ⇒ epidermal dendritic cells) — phagocytic (macrophage) cells play a role in immunity that arise from bone marrow.

    4. Merkel cells — form touch receptors ⇒ Merkel discs associated with sensory nerve ending at the epidermal-dermal junction
  5. name the layers of the epidermis and describe the characteristics of each.
    4/5 LAYERS OF THE EPIDERMIS – all 5 layers are present in thick skin (palms, finger tips & soles

    Stratum corneum (horny layer) – accounts for up to 3⁄4 of epidermal thickness (20 – 30 cell layers thick)

    Stratum lucidum (clear layer) – very thin translucent band with flattened, dead keratinocytes with indistinct boundaries, not present in regions of thin skin

    • Stratum granulosum (granular layer) – the cells contains an abundance of granules.
    • – cells flatten, nuclei & organelles disintegrate due to inadequate nourishment.

    Stratum spinosum* (spiny or prickly layer) – appear spiky and contain a weblike system of intermediate filaments made of prekeratin protein.

    Stratum basale* (basal layer) – constantly undergo mitotic cell division. (single cell layer) also known for its alternate name -- stratum germinativum

    *only layer to receive adequate nourishment is spinosum & basale layers.
  6. name the layers of the dermis and describe the characteristics of each.
    • Major Layers of dermis – a strong, flexible connective tissue layer.
    • 1). Papillary layer – thin, superficial, heavily invested w/blood vessels contain free nerve
    • endings (pain receptors) & Meissner’s corpuscles (touch receptors).
    • – fingerlike projections on its superior surface

    • 2). Reticular layer – deepest layer, accounts for about 80% of dermis
    • – typical dense irregular connective tissue.
  7. describe the various skin conditions:
    • Bedsores (decubitus ulcers)
    • Jaundice Addison’s disease
    • Blackheads
    • Acne
  8. describe the distribution and function of the skin derivatives – cutaneous gland, nail, and hair.
    ACCESSORY ORGANS OF THE SKIN: all of the epidermis, but reside in dermis.

    A. Cutaneous glands (2 categories)

    • Sweat (sudoriferous) glands :
    • – distributed over the entire skin surface, except nipples & parts
    • of external genitalia.

    – body’s heat regulation controlled by nervous system.

    • Sebaceous glands – found nearly all over the skin, except on palms & soles of feet.
    • – secrete oily substances & fragmented cells ⇒ sebum.
    • – active during puberty especially when ♂ hormones (androgens) is produced.

    • B. Hairs (or pili) – enclosed in hair follicles that are found over the entire body surface, except
    • for thick-skinned areas:

    • – palms of the hands & soles of feet,
    • – parts of external genitalia,
    • – the nipples & the lips
    • – structure consists of medulla, a central region (cortex), cuticle.

    • C. Nails – hornlike or scalelike modification of the epidermis that forms a clear protective
    • covering, consist of several named parts:

    • – Body – visible attached portion.
    • – Free edge – portion of the nail that grows out away from the body.
    • – Root – embedded in skin & adheres to an epithelial nail bed.
    • – Nail folds – borders of the nail overlap by skin folds.
    • – Eponychium or cuticle – thick proximal nail fold projects onto nail.
    • – Lunula – proximal region of nail that appears white crescent.
    • – transparent & nearly colorless, but appears pink.
Card Set
Ex 7: Itergumentary System