Anatomy Chapter 5 Notes

Layers of the integument (skin)

1. Epidermis

2. Dermis

3. Hypodermis (subcutaneous) layer

Structural and functional relationship of epidermis

• Structure- the epidermis is a stratified squamous epithelium; made of epithelial cells

• Function- a tough, waterproof protective barrier that shields internal body tissues from environmental damage, pathogens, and fluid loss

  • Simpler version: to act as a tough, waterproof outer barrier that protects the body from environmental harm

Structural and functional relationship of dermis

• structure- dense connective tissue and fibrous proteins

• Function- provide structural support, strength, and elasticity to the skin while housing vital structures that supply nutrients, sense the environment, and regulate body temperature

What are the layers of the epidermis (top to bottom)?

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum basale

Mnemonic: Come, let’s get sun burned

How many thin layers of the epidermis are there, and what are they?

4 layers:

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

How many thick layers of the epidermis are there, and what are they?

5 layers:

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum basale

What are the layers of the dermis?

1. Papillary dermis (upper layer)

2. Reticular dermis (lower layer)

Papillary layer function (dermis)

Supply the outer layer of skin (epidermis) with nutrients and remove waste products

Reticular layer function (dermis)

provides structural strength, elasticity, and support to the skin

How is skin color determined?

by the amount, type, and distribution of a pigment called melanin in your skin cells, which is controlled by multiple genes working together

Skin color (melanin, carotene, hemoglobin)

• melanin- makes skin darker

• Carotene- makes your skin yellow or orange

• Hemoglobin- gives skin pink, red, or blue-red tones

Eccrine sweat gland (dermis)

secrete clear, watery sweat that evaporates from your skin to cool your body down

Arrector pili muscle location and function

• Location- dermis

• Function- involuntarily contract and pull hair follicles upright

Sebaceous (oil) gland (dermis)

produce and secrete sebum, an oily mixture of lipids that lubricates and protects the skin and hair

Hair follicle (dermis)

grow your hair

Hair root (dermis)

anchor the hair strand within the skin and actively produce new hair through rapid cellular division

Dermal vascular plexus (dermis)

Regulate body temperature and supply nutrients to the skin

Sensory nerve fiber with free nerve endings (dermis)

unencapsulated receptors that detect pain, temperature, itch, and crude touch

Lamellar corpuscle (dermis)

detect deep pressure, stretch, and high-frequency vibrations

Hair follicle receptor (dermis)

detects light touch and hair movement

Where is thin skin found?

almost everywhere

Where is thick skin found?

On the palm of hands and soles of feet

How does hair growth work?

happens inside tiny pockets in the skin called hair follicles, where fast-multiplying cells create a hard protein called keratin that pushes upward to form the visible hair strand

How does baldness occur?

where hair follicles shrink over time and stop producing new hair

What is the difference between eccrine and apocrine sweat glands?

• eccrine-

  • Found everywhere on the body

  • Goes through pores

  • Cools the body down; odorless

• Apocrine

  • Found on the armpits, groin, and scalp

  • Goes into hair follicles

  • Reacts to emotional stress and hormonal changes; creates body odor when broken down by skin bacteria

What are the sensory receptors?

• free nerve endings

• Pacinian corpuscles (lamellar corpuscles)

• Hair follicle receptor

• Meissner’s corpuscle

Pacinian corpuscles location and function

• location- deep in the skin and internal tissues

• Function- detect high-frequency vibrations and deep pressure

Hair follicle receptor location and function

• location- surrounds hair follicle which is superficial to the hair

• Function- act as a sensitive touch receptor

Meissner’s corpuscle location and function

• location- superficial layers of the skin

• Function- detect light touch and low-frequency vibrations

Free nerve endings location and function

• location- throughout the body

• Function- detect pain, temperature, and crude touch

What are the cells of the epidermis?

• keratinocytes

• Melanocytes

• Dendritic cell

• Merkel cell

keratinocytes

• main cells in the outer layer of your skin

• Produce a protein called keratin (fibrous protein found in epidermis, hair, and nails that makes those structures hard and water resistant)

• Contain melanin, but don’t make their own melanin

melanocytes structure and function

• produce a pigment called melanin (brown pigment)

• Structure- have projections/processes which fill in the gap between keratinocytes

• Melanin travels through the projections and is transferred into the keratinocytes

*fun fact: in response to UV radiation, melanin orients itself

Dendritic cell

Protective cells that engulf antigens, migrate to lymph nodes, and present the antigen to T cells, causing them to activate and mount an immune response

• phagocytic

Merkel cell

Specialized touch receptors that detect light touch, tactile touch, and pressure

What is the dermis made of?

connective tissue

What are the functions of the skin?

1. Protection

2. Excretion

3. Temperature regulation

4. Sensation

5. Blood reservoir

6. Excretion

protection (skin)

1. Physical protection- layers

2. Chemical protection- keratin and produces antibacterial substances

3. Biological protection- cells for the immune system called dendritic cells

excretion (skin)

Urea and salt

Temperature regulation (skin)

1. Sweat glands- evaporative cooling

2. Arrector pili muscles

3. Blood vessel diameter

Sensation

form nervous system receptors

Blood reservoir (skin)

5% of your blood is stored in the skin

metabolic functions

produced vitamin D

What are the three types of burns?

1. First-degree burns

2. Second-degree burns

3. Third-degree burns

First-degree burn characteristics, layer affected, and healing time

• characteristics- localized redness, swelling, and pain

• Layer affected- only epidermis

• Healing time- two to three days

Second-degree burn characteristics, layer affected, and healing time

• characteristics- similar to first-degree burns, but blisters also appear; red and painful

• Layer affected- injure the epidermis and the upper region of the dermis

• Healing time- three to four weeks

Third-degree burn characteristics, layer affected, and healing time

• characteristics- burned area appears gray-white, cherry red, or blackened; no swelling

• Layer affected- all layers of skin

• Healing time- several weeks to several years

Is the hypodermis part of the skin?

NO

What is the function of the hypodermis?

providing insulation, energy storage, and shock absorption