BIO201 Lab 7

The skin has two distinct regions. The superficial layer is the ____ , and the underlying connective tissue is the _______ .

Epidermis; Dermis

Describe two integumentary system mechanisms that help regulate body temperature.

(1) When capillary blood flow to the skin is enhanced (by nervous system controls), heat radiates from the skin surface; restriction of blood flow conserves body heat. (2) Activity of sweat glands (i.e., when perspiration evaporates from the skin surface, heat is lost).

cells of the epidermis

-keratinocytes -Melanocytes -dentritic cells -tactile (merkel cells)

The accessory organs of the skin

1. Cutaneous glands2. Hair3. Nails

Two primary regions of hair

1. Hair shaft 2. Hair root

Two primary layers of the dermis regions

1. Papillary layer 2. Reticular layer

Sweat (sudoriferous) glands

Exocrine glands that are widely distributed all over the skin; Outlet known as pores.

Nail bed

Extension of the stratum basle beneath the nail.

Dermal Papillae

Fingerlike projections from its superior surface which attach to the epidermis layer and produce fingerprints.

Thick skin of the epidermis contains ________ layers.

Five 1. Corneum 2. Lucidum 3. Granulosum 4. Spinosum 5. Basale

Sebaceous (oil) glands

Found nearly all over skin; Their ducts usually empty into a hair follicle, but some open directly on the skin surface; Produce sebum. secretes a lubricant for hair and skin

Apocrine sweat glands

Found predominantly in the axillary and genital area; Secrete the basic components of eccrine sweat plus proteins and fat-rich substances; Produce B.O. less numerous type of sweat-producing gland; found mainly in the pubic and axillary regions

Stratum Spinosum (spiny layer)

Several layers of cells that contain thick, weblike bundles of intermediate filaments made of a pre-keratin protein first appear; Cells appear to be spiky

Nail folds

Skin folds that overlap the borders of the nail.

Arrestor pili muscle

Small band of smooth muscle cells connect each hair follicle to the papillary layer of the dermis; Causes goosebumps pull hair upright during fright

Melanocytes

Spidery black cells that produce melanin. main function is pigmentation

dendritic cells main function

immunity

3 common fingerprint patterns

loops, arches, whorls

Hair bulb

A collection of well-nourished epithelial cells at the base of the hair follicles.

Keratin

A fibrous protein that gives the epidermis its durability and protective capabilities.

Sebum

A mixture of oily substances and fragmented cells that acts as a lubricant to keep the skin soft and moist and keeps the hair from being brittle.

Hair Follicle

A structure (sheath) formed from both epithelial and dermal (connective tissues) cells.

All the following are functions of the skin except: a. excretion of body wastes b. insulation c. protection from mechanical damage d. site of vitamin A synthesis

D. Site of vitamin A synthesis

The most superficial layer of the epidermis is the: a. stratum basale b. stratum granulosum c. stratum spinosum d. stratum corneum

D. Stratum Corneum

Reticular Layer

Deepest layer of skin; composed of dense irregular connective tissue

Nails

Hornlike derivatives of the epidermis.

Hypodermis (superficial fascia)

Immediately deep to the dermis; Not considered part of the skin; Primarily consists of adipose tissue.

Keratinocytes

Keratin cells; Most abundant (numerous) epidermal cells; Main function is to produce keratin fibrils. main function is protection

Hair matrix

Layer of actively dividing epithelial cells that is located on tip of the hair papilla.

Papillary layer

The more superficial dermal region composed of areolar connective tissue. - responsible for fingertips

Stratum Corneum (horny layer)

The outermost layer consisting of 20-30 layers of dead, scalelike keratinocytes that constantly slough off contains dead cells

Nail root

The part that is embedded in the skin and adheres to an epithelial nail bed.

Free edge

The portion of the nail that grow out away from the body.

Lunule

The proximal region of the thickened nail matrix, which appears as a white crescent moon.

Hyponychium

The region beneath the free edge of the nail

Nail matrix

The thickened part of the nail bed containing germinal cells responsible for nail growth.

Nail body

The visible attached portion.

Epidermis (Avascular)

composed of keratinized stratified squamous epithelium consisting of four distinct cell types and four to five distinct layers.

The portion of a hair that projects from the surface of the skin is known as the: a. bulb b. root c. matrix d. shaft

d. Shaft

The reticular layer of the dermis contains __________.

pressure receptors (lamellar corpuscles)

hair and nail

primarily dead/keratinized cells

Circle the correct underlined term. The ducts of (sebaceous / sweat) glands usually empty into a hair follicle but may also open directly on the skin surface.

sebaceous

cutaneous receptors

specialized nerve endings that respond to temp, tough, etc.

Circle True or False. Nails originate from the epidermis.

True

Figure7.2 The main structural features in epidermis of thin skin.

(a) Photomicrograph depicting the four major epidermal layers (4303). (b) Diagram showing the layers and relative distribution of the different cell types. Keratinocytes (orange), melanocytes (gray), dendritic cells (purple), and tactile (Merkel) cells (blue). A sensory nerve ending (yellow) extending from the dermis is associated with a tactile cell, forming a tactile disc (touch receptor). Notice that the keratinocytes are joined by numerous desmosomes. The stratum lucidum, present in thick skin, is not illustrated here

The integument

- considered an organ system because it consists of multiple organs, the skin and its accessory organs - tough yet pliable, a characteristic that enables it to withstand constant insult from outside agents

Two primary categories of cutaneous glands

1. Sebaceous (oil) glands 2. Sweat (sudoriferous) glands

Five layers of epidermis (from superficial to deep)

1. Stratum Basale 2. Stratum Spinosum 3. Stratum Granulosum 4. Stratum Lucidum 5. Stratum Corneum

Two distinct regions of the skin

1. superficial Epidermis (composed of epithelium) 2. Dermis (connective tissue)

Stratum Basale (basal layer)

A single row of cells immediately above the dermis. Its cell are constantly undergoing mitosis to form new cells. location of melanocytes and tactile epithelial cells most rapid cell division

Stratum Granulosum (granular layer)

A thin layer named for the abundant granules its cells contain. layer that secretes a glycolipid that prevents water loss from the skin

Acne

Acne is an active infection of the sebaceous glands.

Blackheads

An accumulation of dried sebum bacteria, and melanin from epithelial cells in the oil duct.

Circle the correct underlined term. (Eccrine / Apocrine) sweat glands are found primarily in the genital and axillary areas.

Apocrine

________ is a yellow-orange pigment found in the stratum corneum and the hypodermis. a. Keratin b. Melanin c. Carotene d. Hemoglobin

B. Carotene

Melanin

Brown-to-black pigment; Provides a protective pigment umbrella over the other layers of the epidermis. (freckle is a concentration of melanin)

These cells produce a brown-to-black pigment that colors the skin and protects DNA from ultraviolet radiation damage. The cells are: a. dendritic cells b. melanocytes c. keratinocytes d. tactile cells

C. Melanocytes

Eccrine sweat glands

Gland that produce clear perspiration consisting primarily of water, salts, and urea; Heat-regulating apparatus role in temp control

Henna tattoos are temporary tattoos that last about 2 weeks. Hypothesize why henna tattoos do not last as long as permanent tattoos

Henna tattoos utilize a superficial application and only stain or color the cells of the epidermis. The color fades and disappears as these cells are pushed to the surface of the skin and replaced. This is not the case with permanent tattoos as the ink is injected into the dermal layer of the skin, using a needle, where it is retained for a much longer time.

Tactile (Merkel) cells

Occasionally spiky hemispheres that, in combination with sensory nerve endings, form sensitive touch receptors called Tactile of Merkel discs located at the epidermal-dermal junction.

Stratum Lucidum (clear layer)

Present only in thick skin. A very thin transparent band of flattened, dead keratinocytes with indistinct boundaries.

Eponychium

Projection of the thick proximal nail fold commonly called the cuticle.

Hair shaft

Region of the hair projecting from the skin.

Hair root

Region of the hair that is beneath the surface of the skin and is embedded within the hair follicle.

Skin functions

1. isolates and cushions the underlying tissue 2. protects the body from abrasion 3. protects the body from harmful chemicals 4. prevents water loss from internal reserves protection, insulates and cushions the underlying body tissues and protects the entire body from abrasion, exposure to harmful chemicals, temperature extremes, and bacterial invasion The hardened uppermost layer of the skin prevents water loss from the body surface. The skin's abundant capillary network (under the control of the nervous system) plays an important role in temperature regulation by regulating heat loss from the body surface. other functions: acts as an excretory system, urea, salts, and water are lost through spin pores in sweat, metabolic duties; sense organs for touch, pressure, pain, and temperature are located here