Biology Chapter 5: Integumentary System

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Questions and Answers

Which type of connective tissue is found in the papillary region of the dermis?

Loose CT with few fibers

Dense irregular CT

Dense regular CT with collagen fibers

Areolar CT with elastic fibers (correct)

What is the primary function of sebaceous glands?

To produce sweat for thermoregulation

To detect touch and pressure

To secrete sebum that coats hairs and holds moisture in the skin (correct)

To synthesize vitamin D

What is the main function of eccrine sweat glands?

To secrete sweat for thermoregulation and excretion (correct)

To detect pain and pressure

To synthesize vitamin D

To produce sebum for hair growth

Which layer of the skin attaches the dermis to underlying structures?

Hypodermis Signup and view all the answers

What is the function of arrector pili muscles?

To make hair stand up in response to cold or emotional stress Signup and view all the answers

What is the function of the reticular region of the dermis?

To contain bits of adipose, hair follicles, nerves, oil and sweat glands Signup and view all the answers

What is the function of the integumentary system in vitamin D synthesis?

To synthesize an inactive form of vitamin D upon UV exposure Signup and view all the answers

What is the function of the nails?

To grasp and manipulate objects, and for scratching Signup and view all the answers

What is the primary function of keratinocytes in the epidermis?

Produce fibrous protein keratin for protection Signup and view all the answers

Which layer of the epidermis is also known as stratum germinativum?

Stratum basale Signup and view all the answers

What unique characteristic defines the stratum lucidum?

It is found only in thicker areas of the skin, like palms and soles Signup and view all the answers

What role do dendritic cells play in the epidermis?

They are involved in the immune response Signup and view all the answers

The main function of melanocytes is to produce which pigment?

Melanin Signup and view all the answers

What does the stratum granulosum primarily consist of?

Dead keratinocytes containing keratohyaline granules Signup and view all the answers

What important barrier is formed by lamellar granules in the epidermis?

Waterproof barrier to prevent moisture loss Signup and view all the answers

How thick can the epidermis range in humans?

0.1 mm to 2 mm Signup and view all the answers

Study Notes

Epidermis

Keratinized stratified squamous epithelium
Composed of:
- Keratinocytes (90%): produce fibrous protein keratin, provide protective properties of skin
- Melanocytes (8%): produce melanin, protect from UV light
- Dendritic cells: involved in immune response, produced in red bone marrow
- Tactile epithelial cells: associated with nerve endings, important in sense of touch
Thickness: 0.1 mm – 2 mm
Layers of epidermis (strata, from deep → superficial):
- Stratum basale: one row of mainly cuboidal or columnar keratinocytes, melanocytes and tactile cells scattered among keratinocytes
- Stratum spinosum: 8-10 cells thick, more superficial keratinocytes are flatter
- Stratum granulosum: 3-5 cells thick, flattened keratinocytes, nuclei and organelles degenerate, lots of keratin
- Stratum lucidum: only in thicker skin, 3-5 cells thick, very flat, dead keratinocytes
- Stratum corneum: 25-30 cells thick, very flat, dead keratinocytes, waterproof barrier that protects from light, heat, chemicals and invaders

Dermis

Connective tissue with embedded structures
Cells include: fibroblasts, macrophages
Contains: blood vessels, nerves, glands and hair follicles
Regions of dermis:
- Papillary region: areolar CT with elastic fibers, projects into epidermis as dermal papillae, loops of capillaries, touch receptors
- Reticular region: dense irregular CT with lots of collagen and some elastin, contains bits of adipose, hair follicles, nerves, oil and sweat glands

Hypodermis

Attaches dermis to underlying structures
Composed of: areolar and adipose tissue
Also known as subcutaneous layer or superficial fascia
Contains: blood vessels and nerves

Functions of Integumentary System

Temperature regulation: evaporation of sweat decreases body temperature, changes in blood flow
Protection: physical barrier to invasion, dehydration and UV radiation, contains cells of immune system
Sensation: nerve cells with receptors for pain, touch, pressure, temperature
Excretion: water and dissolved substances in sweat
Acts as a blood reservoir: flow can be shifted to hard-working muscles if needed
Vitamin D synthesis: epidermis makes inactive form of vitamin D upon exposure to UV

Derivatives of the Epidermis (skin appendages)

Hair:
- Dead, keratinized cells
- Shaft projects from surface of skin
- Root is beneath skin surface, surrounded by hair follicle
- Functions: protect from light, decrease heat loss, protect eyes and nose from particles, sense of touch, hold chemical signals
Sebaceous (oil) glands:
- Holocrine glands
- Ducts usually open to hair follicle
- Secrete sebum (mix of fats, cholesterol, proteins, salts, pheromones) that coats hairs, holds moisture in skin, and inhibits bacterial growth
Sudoriferous (sweat) glands:
- Eccrine sweat glands:
  - On most skin
  - Ducts open to skin surface
  - Secrete sweat (water, salt, some wastes) for cooling body, excretion, and acidity protects from bacteria
- Apocrine sweat glands:
  - In axillary, genital and anal regions
  - Ducts open to hair follicles
  - Secrete sweat, fats and proteins, may function in sexual signaling
Nails:
- Hard, keratinized cells
- Nail body is visible
- Root is under skin
- Functions: grasp and manipulate objects, scratching

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Description

This quiz covers the structure and functions of the epidermis, including keratinocytes, melanocytes, and dendritic cells. Learn about the role of keratin, melanin, and immune response in the integumentary system.