lecture 4 Integumentary system

Question 1

Describe the three layers of the skin

Answer 1

• Epidermis - Most superficial layer, made of epithelial tissue
• Dermis - Middle layer, made of connective tissue.
• Hypodermis - Deepest layer, not part of the integument, made of connective tissue.

Question 2

Describe the size, thickness and functions of the integument.

Answer 2

•Size: 1.5-2 square meters covering the entire body. 7-8% of body weight. (largest body organ)
Thickness: 1.5-4 millimeters
Functions: protection, prevention of water loss, temperature regulation, immune defense, metabolic regulation, excretion, sensory reception
(remeber P P Times - P.P.T.I.M.E.S)

Question 3

What structures are included in the integumentary system?

Answer 3

The integument or cutaneous layer consists of the skin, nails, hair, sweat glands, and sebaceous glands.

Question 4

Name and briefly describe the 5 layers of the keratinized epidermis. Which are found in thick skin? Which are found in thin skin?

Answer 4

• Stratum Corneum - Apical layer, made of dead cells; top layer
• Stratum Lucidum - only found in thick skin(hands, knees, feet); second layer
• Stratum Granulosum - Form water tight barrier; 3rd layer
• Stratum Spinosum - “spiny” layer; 4th layer
• Stratum Basale - Divides to form the spinosum layer; bottom layer

Remember: Can Loud Girls Sing Bass (Corneum, lucidum, granulosum, spinosum, basale)

Question 5

What is the location and function of keratinocytes found in the epidermis.

Answer 5

Make keratin (found in all 5 layers of the epidermis). Most abundant cell type in epidermis

Question 6

What is the location and function of Epidermal dendritic cells found in the epidermis.

Answer 6

Found in stratum spinosum

Controls immune response

Question 7

What is the location and function of Tactile cells (merkel cells) found in the epidermis.

Answer 7

Associated with senses(touch/pressure)
Can become malignant.
Found in stratum basale

Question 8

What is the location and function of Melanocytes found in the epidermis.

Answer 8

Make melanin

Found in stratum basale

Question 9

Explain how hemoglobin contributes to skin color.

Answer 9

Carries oxygen in the blood, can make the skin red(blushing). If unoxygenated can make skin tone more blue.

Question 10

Explain how melanin contributes to skin color.

Answer 10

determines how tan or dark you are

Question 11

Explain how carotene contributes to skin color.

Answer 11

Causes yellowing of skin, mainly if you eat way too much food with carotene in it.

Question 12

Describe the structure of the dermis, including the cells and the extracellular matrix.

Answer 12

The dermis has two layers:

•Papillary layer - made of areolar connective tissue
Contains Dermal papillae
•Reticular layer - made of dense irregular connective tissue.

Vascular
Innervated

Question 13

The papillary layer of the dermis is rich in blood vessels and sensory nerve endings. Therefore, what are its main functions?

Answer 13

Nourishment and sensation. Also to feed the epidermis with oxygen and blood, as well as to collect waste products.

Question 14

Describe dermal papillae and epidermal ridges.

Answer 14

Dermal Papillae and epidermal ridges look like egg cartons stacked on top of each other, they function to increase the surface area between the layers which facilitates the exchange of nutrients and creates strong surface tension

Question 15

The reticular layer of the dermis is thick and rich in collagen fibers. Therefore, what functions does this layer perform?

Answer 15

The reticular layer functions for support and strength of the skin and plays a role in the ability of the skin to stretch. The orientation of the collagen causes cleavage lines.

Question 16

What structures are typically found in the reticular layer?

Answer 16

Structures - glands, hair follicles, capillaries, veins, blood vessels

Question 17

Describe the structure and functions of the hypodermis (subcutaneous tissue).

Answer 17

Structure: areolar and adipose connective tissue
Function: anchors skin to underlying structures, thermal insulation, energy reserves

** not considered part of integumentary system

Question 18

Describe the basic structure of nails.

Answer 18

• nail matrix (on the inside)
• cuticle (skin on nail)
• lunula (proximal end of nail. whitish from blood vessels being obscured by thickened underlying stratum basale)
• free edge white ends of nails

Nail root, body, and free edge make up nail plate.

Question 19

Describe the basic structure of hair.

Answer 19

• follicle, root and shaft
• contains keratin
• arrector pili muscle (contracts and causes goose bumps)

Question 20

Describe the basic function of hair.

Answer 20

protection, sense touch, reduce heat loss

Question 21

Describe the 3 basic types of hair.

Answer 21

Lanugo (fetal)
Vellus (fine hair on most of the body)
Terminal (head, pubic region, armpit, male facial hair)

Question 22

Describe the basic growth cycle of hair.

Answer 22

• rate of hair growth is about 2 mm/ week

- growth cycles: active phase (2-7 years) dormant phase (3-4 months)

Question 23

Compare and contrast the following glands in terms of basic structure, location in skin layers, location on the body, what is secreted, and function of the secretion.
Merocrine sweat glands
apocrine sweat glands
sebaceous (oil) glands

Answer 23

Glands of the Skin:

Sebaceous (oil) Glands:

• Associated with hair follicles
• Produce lipid material called sebum, which coats epidermis and shaft of hair; provide lubrication and antibacterial activity

Sudoriferous (Sweat) Glands:
Apocrine glands :
-Distributed in axillary, anal, areolar, and pubic regions
-Produces viscous, complex secretion; secretion influenced by hormones; may act in signaling/communication

Merocrine glands:

• Distributed throughout body, except external genitalia, nipples, and lips; especially prevalent on palms, soles, and forehead
• Produce nonviscous, watery secretion; controlled by nervous system; provide some antibacterial protection; function in thermoregulation and excretion; flush surface of epidermis

Question 24

What is a first degree burn

Answer 24

only epidermis is damaged. Redness, pain, and slight edema (swelling). Mild sunburn

Question 25

what is a second degree burn

Answer 25

epidermis & part of dermis damaged. Skin is red, white, or tan, blistered and painful. Severe sunburn, burn from hot liquids or chemicals

Question 26

what is a third degree burn

Answer 26

epidermis, dermis, and subcutaneous layer

Question 27

Name and describe three types of skin cancer.

Answer 27

·Basal Cell Carcinoma:
•Most common type
•Least dangerous type
•Originates in stratum basale

·Squamous Cell Carcinoma:
o Arises from keratinocytes
o dry, scaly on the face

·Malignant Melanoma:
•Most deadly type
•Arises from melanocytes (usually a pre-existing mole)
•Early detection is crucial!

Question 28

Explain the cause of acne

Answer 28

Acne (including whiteheads & blackheads)
•Closed and open comedos(sebaceous glands that are plugged with sebum) are white and blackheads, respectively. Bacterial infection can cause swelling and redness.
• Acne may become abundant beginning at puberty, because increases in sex hormone levels stimulate sebaceous gland secretion, making the pores more prone to blockage.

Question 29

Explain the cause of baldness

Answer 29

Baldness (alopecia)

• a result of aging happens with both men and women.
• causes are genetic influences & hormonal influences –testosterone causes terminal hair to be replaced with vellus hair

Question 30

Explain the cause of birthmarks

Answer 30

Birthmarks (brown, red, purple)
AKA Nevus
Purple/red-results in skin discoloration due to blood vessels that proliferate and form a benign tumor
Brown- localized overgrowth of melanin-forming cells

Question 31

Explain the cause if blisters

Answer 31

Caused by a burn or by excessive friction

Question 32

Explain the cause of cleavage lines

Answer 32

• Cleavage lines correspond with the orientation of collagen bundles
• Important for surgeons to cut parallel to lines of cleavage for faster healing

Question 33

Explain the cause of fingerprints

Answer 33

Formed by large folds and valleys of the dermis and epidermis

Question 34

Explain the cause of freckles and moles

Answer 34

• Freckles- Yellowish or brown spots from excessive melanocyte activity, not increased melanocyte cells. Causes are genetic & sun exposure
• Moles- (Nevus) Overgrowth of melanin-forming cells. harmless unless it mutates and becomes malignant

Question 35

Explain the cause of goosebumps

Answer 35

• Come as a result of the arrector pili muscle causing hair to stand up and dimple the skin
• Sympathetic nervous system (fight or flight)

Question 36

Explain the cause of stretchmarks/Striae

Answer 36

Torn collagen as a result of pregnancy, weight lifting, weight gain or a growth spurt.

Question 37

Explain the cause of sun tanning

Answer 37

-Melanin pigment surrounds the keratinocyte nucleus, it absorbs ultraviolet (UV) radiation in sunlight.

• Prevents damage to nuclear DNA and darkens melanin already present
• Stimulates melanocytes to make more melanin.

Question 38

Explain the cause of wrinkles during aging

Answer 38

• Decreased flexibility and thickness of the dermis

* Fibroblasts aren’t as active anymore

Question 39

Explain Hemangioma skin markings

Answer 39

Proliferation of blood vessels

Bright red or deep purple in color