Anatomy and Physiology Chapter 5

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Questions and Answers

Which of the following are functions of the skin? (Select all that apply)

Excretion and Absorption (correct)
Respiration
Vitamin D synthesis (correct)
Protection (correct)

What are the protective elements of skin? (Select all that apply)

Keratin (correct)
Keratinocytes
Glandular Secretions (correct)
Melanin (correct)

What is thermoregulation?

Controls internal temperature

Why is Vitamin D synthesis important?

You need Vitamin D to absorb calcium Signup and view all the answers

What is the epidermis?

Superficial layer of skin that is avascular Signup and view all the answers

What are keratinocytes?

90% of skin cells that produce keratin Signup and view all the answers

What function do melanocytes serve?

They produce melanin and absorb UV radiation Signup and view all the answers

What do Langerhans cells do?

They have an immune function Signup and view all the answers

What function do Merkel cells serve?

Touch sensation Signup and view all the answers

What are the layers of skin from superficial to deep?

Dermis (B), Epidermis (C) Signup and view all the answers

List the epidermal layers from deep to superficial.

Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidum, Stratum Corneum Signup and view all the answers

What is the stratum basale?

Deepest layer where keratinocytes, melanocytes, Langerhans cells and Merkel cells are present and mitosis occurs. Signup and view all the answers

What happens in the stratum spinosum?

Keratinocytes and Langerhans cells are present and melanocyte production occurs. Signup and view all the answers

What is produced in the stratum granulosum?

Lamellar granules; apoptosis occurs here. Signup and view all the answers

Where is the stratum lucidum found?

Present only in thick skin Signup and view all the answers

What is the stratum corneum?

Outermost layer that contains keratin and is continuously shed. Signup and view all the answers

What is the dermis?

Deep layer beneath the epidermis that is vascular and includes the papillary and reticular layers. Signup and view all the answers

What characterizes the papillary layer?

Areolar connective tissue with dermal papillae (finger-like projections). Signup and view all the answers

What is found in the reticular layer?

Thickest layer made of dense and irregular connective tissue. Signup and view all the answers

What is the hypodermis?

Not a part of the skin. Signup and view all the answers

Which of the following pigments contribute to skin color? (Select all that apply)

Melanin (A), Hemoglobin (C), Carotene (D) Signup and view all the answers

What does hemoglobin do?

Pigment in red blood cells that carries oxygen. Signup and view all the answers

What is carotene?

An ingested pigment that accumulates in the stratum corneum, appearing orangish-yellow. Signup and view all the answers

What is melanin?

Only pigment synthesized in the skin. Signup and view all the answers

Albinism indicates that an individual is capable of producing melanin.

False (B) Signup and view all the answers

What is vitiligo?

Loss of melanocytes in patches of skin. Signup and view all the answers

What are the functions of hair?

Protection and sensing light touches. Signup and view all the answers

What are the anatomical parts of hair?

Shaft, root, hair bulb, hair papilla, matrix, arrector pili muscle. Signup and view all the answers

What is the shaft of hair?

(Inside skin layer) Medulla, cortex, cuticle Signup and view all the answers

What is the root of hair?

The part including the medulla, cortex, cuticle, internal root sheath, external root sheath, and dermal root sheath. Signup and view all the answers

What is a hair follicle?

Surrounds the root of the hair. Signup and view all the answers

What is alopecia?

Condition characterized by rapid hair loss in a sharply defined area. Signup and view all the answers

What are the different skin exocrine glands? (Select all that apply)

Merocrine glands (A), Apocrine glands (C), Sebaceous glands (D) Signup and view all the answers

What is the function of sebaceous glands?

Secrete sebum to prevent hair from drying out and keep skin soft. Signup and view all the answers

What is sebum?

Prevents hair from drying out, keeps skin soft and pliable. Signup and view all the answers

What are sudoriferous glands?

Glands that secrete sweat. Signup and view all the answers

What characterizes merocrine glands?

Simple tubular, found in palms, soles, and forehead, duct terminates on the epidermis. Signup and view all the answers

Where are apocrine glands found?

In armpit and genital regions. Signup and view all the answers

What is ceruminous gland responsible for?

Excretes cerumen (earwax). Signup and view all the answers

What is cerumen?

Sticky barrier that stops the entrance of foreign bodies into the ear. Signup and view all the answers

What are nails composed of?

Tightly packed keratinized cells. Signup and view all the answers

What is the nail body?

Visible portion of nail. Signup and view all the answers

What is lunula?

The white, thickened area of the stratum basale. Signup and view all the answers

What is nail root?

Part of the nail that is under the skin. Signup and view all the answers

What is eponychium?

The cuticle of the nail. Signup and view all the answers

What are the degrees of burns?

All of the above (D) Signup and view all the answers

What characterizes a first degree burn?

Hurts epidermis; typically a sunburn. Signup and view all the answers

What characterizes a second degree burn?

Damage to the dermis and hurts epidermis, with blistering. Signup and view all the answers

What characterizes a third degree burn?

Damage to all layers of skin; might require a skin graft. Signup and view all the answers

What is the rule of nines?

Used to identify the depth and severity of a burn. Signup and view all the answers

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Study Notes

Functions of Skin

Provides protection against environmental hazards.
Regulates body temperature through thermoregulation.
Allows cutaneous sensation for touch, temperature, and pain.
Synthesizes Vitamin D, essential for calcium absorption.
Acts as a blood reservoir holding a significant volume of blood.
Facilitates excretion and absorption processes.

Protective Elements of Skin

Keratin: Provides structural strength, found in the epidermis.
Lipids: Maintain skin hydration and barrier function.
Glandular Secretions: Contribute to skin's antimicrobial properties.
Melanin: Offers protection from UV radiation, giving skin color.

Skin Structure

Epidermis: Avascular, composed of multiple layers and four main cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells.
Keratinocytes: Make up 90% of epidermal cells, crucial for producing keratin.
Melanocytes: Account for 8% of skin cells and synthesize melanin to absorb UV radiation.
Langerhans Cells: Function in the immune response.
Merkel Cells: Involved in the sensation of touch.

Epidermal Layers

Stratum Basale: Deepest layer where cell mitosis occurs; contains keratinocytes, melanocytes, Langerhans, and Merkel cells.
Stratum Spinosum: Contains keratinocytes and Langerhans cells; site of melanocyte production.
Stratum Granulosum: Contains lamellar granules; where apoptosis occurs.
Stratum Lucidum: Present only in thick skin, provides an additional barrier.
Stratum Corneum: Outermost layer, composed of keratin, continuously shed.

Dermis and Hypodermis

Dermis: Deep layer beneath the epidermis; vascular with two layers: papillary and reticular.
Papillary Layer: Made of areolar connective tissue; contains dermal papillae.
Reticular Layer: Thickest layer, comprised of dense irregular connective tissue.
Hypodermis: Subcutaneous layer not considered part of the skin.

Skin Color Factors

Hemoglobin: Oxygen-carrying pigment in red blood cells; influences skin tone and coloration.
Carotene: Accumulates in the stratum corneum; provides orangish-yellow color.
Melanin: Only pigment produced in the skin; irregularities lead to freckles, albinism (lack of melanin), and vitiligo (patchy loss of melanocytes).

Hair Anatomy and Functions

Functions of Hair: Provides protection and detects light touch.
Structures: Comprises the shaft (with medulla, cortex, and cuticle) and root (which includes internal and external root sheaths).
Follicles: Surround the hair root, playing a vital role in hair growth.
Alopecia: Characterized by hair loss due to varying causes (genetic, hormonal, stress).

Skin Glands

Sebaceous Glands: Holocrine glands that secrete sebum; responsible for skin hydration and protection.
Sudoriferous Glands: Divided into merocrine (watery secretion for temperature regulation) and apocrine glands (thicker secretion activated during stress and puberty).
Ceruminous Glands: Found in the ear, producing cerumen (earwax) to trap foreign particles.

Nails

Comprised of tightly packed keratinized cells.
Nail Anatomy: Includes visible parts like the free edge, body, lunula, cuticle (eponychium), and root.
Lunula: Thickened stratum basale appearing white at the base of the nail.

Burns

Classifications: 1st degree (epidermis damage, e.g. sunburn), 2nd degree (epidermis and partial dermis damage, blistering), 3rd degree (full thickness damage requiring skin grafting).
Rule of Nines: A method to assess the extent and severity of burns in adults.

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