Integumentary System

Integumentary system

Skin, hair, and nail

Functions of the integumentary system

1. Protection

2. Prevention of water loss and water gain

3. Temperature regulation

4. Metabolic regulation

5. Immune defense

6. Sensory reception

7. Secretion

2 main parts of the integumentary system

1. Skin

2. Skin accessories

Skin accessories

1. Hair

2. Nails

3. Glands

4. Sensory receptors

2 major layers of skin

1. Epidermis

2. Dermis

Epidermis

Structure: Outer layer of skin.

Keratinized stratified squamous ET

Avascular.

Consists of layers

Layers of the epidermis

1. Stratum basale

2. Stratum spinosum

3. Stratum granulosum

4. Stratum lucidum

5. Stratum corneum

Stratum basale

Deepest layer of the epidermis.

As upper layer of sloth off, makes new skin cells to replace and move upward

2 cell types:

1. Stem cells

2. Melanocytes

Keratinocytes

Produce keratin

Melanocytes

Produce melanin

Melanin

A pigment molecules that prevents damage to the skin by absorbing UV light

Stratum spinosum

2nd layer from the bottom layer.

2 types of cells:

1. Keratinocytes - alive

2. Dendritic cells

Dendritic cells

Eat bacteria and microbes.

Immune cells, like macrophages

Stratum granulosum

3rd layer from bottom layer

Cells:

Keratinocytes - dying, further from source of nutrients

Creates more room for packing of keratin

Secretes glycolipids - hydrophobic, prevent water loss

Stratum lucidum

4th layer from bottom layer

Cells:

Keratinocytes, dead

Contain maturing keratin

Looks clear

Lucid = clear

Function: extra strength

Layer only found in thick skin

Stratum corneum

5th layer

Most superficial layer

Flaky

Cells:

Keratinocytes = dead

Flakes are collections did dead keratinocytes

Skin exposed to a lot of friction builds thicker layer = Calus = protection from damage

2 types of skin

1. Thin

2. Thick

Thick skin

Each skin layer is thicker and has one extra layer = stratum lucidum

Epidermis ridge present

Location: fingertips, palms of hands, soles of feet

Epidermal ridges

Fingerprints

Thin skin

Most skin on the body.

Has hair.

Has 4 layers.

Dermis

Areolar CT And dense irregular CT

Function: support and nourishment of epidermis

2 layers of the dermis

1. Papillary layer

2. Reticular layer

Papillary layer

Contains projections into epidermis

Areolar CT

Function: metabolic support and thermoregulation

Reticular layer

Dense irregular CT

Function: support for structure from collagen and elastic fibers for elasticity

Reticular = network not reticular fibers

Hypodermis

Below the skin

AKA subcutaneous layer

Adipocytes

Adipose CT

Function: insulation, energy storage

Nails

Modified stratum corneum

Hard keratin

Hair

Column of dead keratinocytes with hard keratin

Grows from the hair follicle

Derivative of the epithelium

Function of hair

1. Protection

2. Heat retention

3. Sensory reception

4. Visual identification

Hair shaft

Portion of the hair that extends beyond the skin surface

Hair root

Embedded in the skin

Below the surface of the skin

Hair follicle

An oblique tube that surrounds the hair root

Extends into the dermis and sometimes into the subcutaneous layer

Function: produce new hair

Hair bulb

Consists of epithelial cells

A swelling at the base where the hair originates in the dermis

Arrector pili

Muscle

Extends from the dermal papillae to the mid region of the hair follicle

Thin ribbons of smooth muscle

Stimulated in response to an emotional state

Upon stimulation, the muscle contracts pulling on the follicle and elevating the hair to produce cutis anserina, aka goose bumps

Function: helps squeeze sebaceous gland to secrete sebum

Sebaceous glands

Function: produce and secrete sebum for lubrication and antibacterial activity

Location: hair follicles

Sebum

Produced by the sebaceous glands

Lipid material which coats the epidermis and shaft of hair

Acne

Inflamed hair follicle due to sebum secretion

Merocrine sweat glands AKA eccrine sweat glands

Function: produce nonviscous watery secretion, normal sweat, regulates body temperature = thermoregulation,

Location: throughout the body

Gland —> duct—> surface of skin

Apocrine sweat glands

Location: axillary, anal, Areolar, and pubic regions

Function: produce viscous complex secretion

Influenced by hormones

Stinky sweat

Modified sweat glands

1. Cerumnous glands = ear wax

2. Mammary glands = milk

Sensory receptors

1. Meissner’s corpuscles

2. Free nerve ending

3. Pacinian corpuscles

4. Ruffini corpuscles

Meissner’s corpuscles

Location: Dermal layer

Structure: Coiled spring

Function: Detects soft fine touch

Free nerve endings

Location: Papillary layer

Function: Sense temperature and pain

Ruffini corpuscles

Function: Sense stretch

Location: reticular layer

Pacinian corpuscles

Structure: looks like an onion slice

Location: reticular layer of the dermis

Function: detects pressure and vibration