THE INTEGUMENTARY SYSTEM

Integumentary System Functions

Protection (chemical, physical, and biological barriers)

Prevents loss of water Temperature regulation Metabolic regulation Immune defense Sensory receptors Excretion by means of secretion

Regions of the Skin

Epidermis

Dermis

HypodermisNOT a part of

the integumentary system

EpidermisThe epidermis is what type of tissue?? Keratinized stratified squamous

epitheliumThick skin has five layers

Thin skin has four layers

Stratum corneum

Stratum lucidum

Stratum granulosumStratum spinosumStratum

basale

Layers of the Epidermis

Stratum corneum Stratum lucidum (only in thick

skin) Stratum granulosum

Keratinization Cells still alive

Stratum spinosum Epidermal dendritic cells

Stratum basale (germinativum) Melanocytes Tactile Cells

Keratinocytes found in all layers

Cells of the Epidermis Keratinocytes-

produce keratin, most abundant

Melanocytes- produce melanin

Epidermal Dendritic Cells (Langerhans Cells)- macrophages in the immune

response

Tactile Cells (Merkel Cells)- sensory receptors

The epidermis is made of ___ epithelium.

1. Simple Squamous

2. Transitional

3. Stratified Squamous

4. Pseudostratified Squamous

Skin Color Hemoglobin – in

blood; causes pink hue in Caucasian skin

Melanin – produced by melanocytes UV exposure darkens

existing melanin and stimulates melanocytes

Carotene – found in plants; yellow to orange pigment

Jaundice – caused by elevated levels of bilirubin in the body

The epidermis is epithelial tissue so what MUST lie directly beneath??

Connective Tissue

Quick Question

Dermis

2 layers: Papillary (areolar) Reticular (dense

irregular) Epidermal Ridges

and dermal papillae

Hypodermis (subcutaneous)

Areolar and adipose connective tissue

Anchors skin to underlying structures

Allows skin to slide freely

Larger in women than men

Nails Scale like

modification of epidermis

Contain hard keratin

Grows from the nail matrix

Hair

Three types of hair: Lanugo

fine downy hair on fetuses

Terminal hair on head, pubic

region, and men’s facial hair

Vellus hair on arms and legs fine hair

Hair Consists of root

and shaft Layers of the

hair:Medulla – central

core not found in all hair

Cortex – surrounds medulla

Cuticle – outermost layer

Location and Functions

Hair can be found EVERYWHERE, except for on the palms, soles, lips, sides of fingers and toes, and parts of the external genitalia

Functions: protects from the sun senses touchreduces heat loss

Hair Growth Rate of hair growth

is about 2 mm/week

Growth cycles – active (2-5 years) and dormant phases (3-4 months)

Why are eyebrows shorter than hair on the head?

Male Pattern Baldness

Genetic and hormonal influences Genetic: 2 alleles, one for

uniform hair growth and one for baldness

Baldness gene is dominant in males

Hormonal: Testosterone causes terminal hair to be replaced by vellus hair

Exocrine Glands Sebaceous (oil) glands

Occur over entire body, except palms and soles

Produce sebum as lubricant

Sudoriferous (sweat) glands Merocrine glands – most

numerous, sweat or sensible perspiration

Apocrine glands – confined to axillary, nipple, anal and genital areas; viscous sweat

Merocrine

Apocrine

Sebaceous

What type of gland secretes oil to lubricate the skin?

1. Sudoriferous

2. Merocrine

3. Apocrine

4. Sebacceous

Burns

First-degree – damages epidermis

Second-degree – damages epidermis and part of the

dermis

Third-degree – damages entire dermis

Types of Skin Cancer

Basal cell carcinoma

Squamous cell carcinoma

Malignant MelanomaRefer to Table 5.4 for more information

Objectives for Next Lecture Describe the general structures

and functions of bone Identify the classifications of bones Understand the two types of bone

formation Describe some disorders of the

skeletal system