A&P Chapter 5

What does the integumentary system consist of?

• Skin

• Hair

• Nails

• Sweat glands

• Sebaceous (oil) glands

What is the epidermis?

Superficial region that consists of epithelial cells/tissue

True or False: Is the Epidermis Avascular

True; lacks blood vessels

What is the dermis layer?

Underlies the epidermis, bulk of the skin, mostly connective tissue

True or False: Is the dermis layer Avascular?

False; Dermis layer is actually Vascular. Has blood vessels

True or False: Is the dermis layer Vascular?

True; has blood vessels

What is the hypodermis?

Subcutaneous layer, deep to skin.

True or False: The hypodermis is NOT apart of the skin

True; not apart of skin but shares similar functions

What is the hypodermis consist of?

Adipose tissue, helps absorbs shock and insulates

The epidermis is mostly?

Keratinized stratified squamous epithelium

What are the 4 cell types in the epidermis?

Keratinocytes, melanocytes, dendritic cells, and Tactile (Merkel) cells

What are keratinocytes?

• Produce keratin (protein that gives skin its protective properties)

• Most cells of the epidermis

• Connected by desmosomes

What are melanocytes?

• Spider shaped, located in the deepest layer of the epidermis

• Produce the pigment melanin, which is packaged into melanosomes

What are dendritic (Langer hans) cells

• Star shaped

• Macrophages in the deep epidermis

  • Ingest foreign objects

  • Key activators of the immune system

What are Tactile (Merkel) cells?

• Spikey shaped

• Sensory receptors that sense touch

Think skin has how many layers?

5

Thin skin has how many layers?

4

What are the 5 layers of the skin?

1. Stratum Basale

2. Stratum spinsosum

3. Stratum granulosum

4. Stratum lucidum (only in thick skin)

5. Stratum corneum

What is the stratum basale?

• Deepest epidermal layer

• Firmly attaches to dermis

• Has stem cells that divide all the time (produces 2 daughter cells)

  • 1 daughter cell goes to the surface, takes 25-45 days

    • Cells die as it gets closer to the surface

  • Other daughter cells stays in layer as stem cell

• 10-25% of layer is made of melanocytes

What is the stratum spinosum (prickly layer)

• Several layers thick

• Pre-keratin filaments attach to desmosomes

  • Allows for resist to tension and pulling

• Among the keratinocytes there are also melanosomes and dendric cells

What is the stratum granulosum layer (granular layer)

• 4-6 cells thick, a thin layer

• Cell appearance changes

  • Cells flatten, nuclei and organelles disintegrate

  • Keratinization occurs

    • Cells obtain keratohyalin granules to help from keratin fibers

    • Cells also gain lamellar granules that slow water loss

• Cells above this layer die

  • Due to being far away from capillaries

What is Keratinization?

Cells fill with keratin

What is the stratum lucidum layer (clear layer)

• Only in thick skin

• Has thin and translucent 2-3 rows of clear, flat , dead keratinocytes

• Lies superficial to stratum granulosum

What is the stratum corneum layer (horny layer)

• 20-30 rows of flat dead cells

• ¾ of epidermal thickness

• Cells may be dead but function to

  • Protect deeper cells from environment

  • Prevent water loss

  • Protect from abrasions and penetrations

  • Acts as a barrier

What is apoptosis?

Cell death

What cells make up the dermis?

• Fibroblasts

• Macrophages

• Sometimes mast cells and WBC

The dermis contains _____, blood vessels, and ______ vessels

nerves, lymphatic

The dermis contains what layers?

• Papillary layer

• Reticular layer

What is the papillary layer?

• Superficial layer of areolar connective tissue, consists of loose, collagen and elastic fibers, and blood vessels

• Contains Dermal papillae

  • In thick skin dermal papillae is on top of dermal ridges or friction ridges

    • Enhances gripping ability

    • Helps with sense of touch

    • Ridges leave unique fingerprint pattern

What is dermal papillae?

• Superficial region of dermis

• Sends finer like projections into epidermis

  • Projections contain capillary loops, free nerve endings, and touch receptors

What is the Reticular layer

• Makes up 80% of dermis thickness

• Contains coarse, dense irregular connective tissue

  • Elastic fibers provide stretch

  • Collagen fibers provide strength

    • Bind water, keeps skin hydrated

  • Contains Cleavage lines and Flexure lines

What is the cutaneous plexus?

Network of blood vessels between the reticular layer and hypodermis

What are cleavage (tension) lines?

• Caused by collagen fibers running parallel to skin surface

  • Externally invisible

What are flexure lines?

• Dermal folds at or near joints

  • Visible on hands, wrists, fingers, soles, toes

What pigments contribute to skin color?

1. Melanin

2. Carotene

3. Hemoglobin

What is melanin?

• Pigment made in skin by melanocytes

• Polymer of amino acids, tyrosine

• Sent to shield DNA of keratinocytes from UV

  • More sun= more produced

• 2 forms: reddish yellow to brownish black

True or False: Skin color difference is due to the amount and form of melanin?

True

Moles and freakles are?

Accumulation of melanin

What is carotene?

• Yellow to orange pigment

• In palms and soles

Where does carotene accumalte?

Stratum corneum and hypodermis

What is hemoglobin (pigament)

• Pink hue in fair skin

• Low levels of melanin

What is cyanosis?

• Blue skin color

  • Low oxygenation of hemoglobin

What is pallor?

• Pale color

• Anemia

  • Low blood pressure

  • Fear

  • Anger

What is erythema?

• Redness

  • Fever

  • Hypertension

  • Inflammation

What is jaundice?

• Yellow cast

  • Liver disorder

What are bruises?

• Black and blue marks

  • Result of clotted blood beneath the skin

Sweat glands are also known as?

Sudoriferous glands

True or False: Sweat glands are on all skin surfaces

False: On all skin surfaces besides nipples and parts of external genital

What are the types of sweat glands?

1. Eccrine (merocrine)

2. Apocrine

What are Eccrine sweat glands

• Most numerous type

• Abundant on palms, soles, and forehead

• Connect to pores

• Coiled tubular gland

• Function in thermoregulation

• Regulated by sympathetic nervous system

• Secrete sweat

What are Apocrine sweat glands

• Confined to axillary and anogenital areas

• Secrete thick milky sweat, contains fatty substances and proteins

• Larger than eccrine glands

• Start functioning at puberty

• Function is unknown

What leads to body oder?

Bacteria breaking down sweat

What is ceruminous glands?

Lining of external ear canal; earwax

What are mammary glands

Secrete milk

What are sebaceous (oil) glands

• Widely distributed

• Develop from hair follicles, Secrete into hair follicles

• Inactive til puberty

• Stimulated by hormones

• Secrete sebum

What are the functions of the skin?

• Protection

• Body temperature regulation

• Cutaneous sensations

• Metabolic functions

• Blood reservoir

• Excretion of wastes

What does Protection look like for the skin?

• Exposed to the environment which can be harmful

• Contains 3 different barriers

What are the types of barriers of the skin?

• Chemical

• Physical

• Biological

What is a chemical barrier?

• Secretes chemicals like sweat, sebum, defensin

• Has acid mantle

• Melanin is a chemical barrier against UV

What is acid mantle?

Low pH of skin retards bacterial multiplication

What is physical barriers of the skin

• Flat, dead, keratinized cells of the statum corneum

• Has some limited penetration to:

• Lipid soluble substances

• Plant oleoresins

• Organic solvents

• Heavy metals

• Some drugs

What are biological barriers of the skin?

• Epidermis has phagocytic cells

• Dermis has macrophage

• DNA absorbs harmful DNA radiation and converts it to heat

What is body temperature regulation?

• Insensible perspiration

What is insensible perspiration?

Normal, resting body temperature, unnoticeable sweat

What is sensible perspiration

When body temperature rises, blood bessels dilate and increases noticeable sweat

What are cutaneous sensory receptors

Part of the nervous system

What are exteroreceptors?

Respond to stimuli like temperature and touch

What are free verve endings?

Sense painful stimuli

True or False: The skin holds up to 5% of total blood volume