Chap4: Body Membranes And Skin

Question 0

Epithelial membranes subdivisions?

Answer 0

• cutaneous membrane
• mucous membrane
• serous membrane

Question 1

Characteristics of body membrane

Answer 1

• cover and line body surfaces
• protect body cavities
• lubricate body cavities

Question 2

Cutaneous membrane

Answer 2

Dry membrane

Outermost protective membrane –> skin

Divided into 2 diff regions:

• superficial epidermis (keratinized stratified squamous ep)
• underlying dermis (mostly dense conn)

Question 3

Mucous membrane

Answer 3

Line body cavities that open to the outside

Adapted for absorption or secretion (digestive , respiratory, excretory, reproductive tracts)

Question 4

Serous membrane

Answer 4

Line body cavities that do not open directly to the outside + cover these organs

Covered by thin layer of serous fluid (secreted by ep) + used for protection (cushion)

Special names according to location :

• peritoneum (abdominal cavities)
• pleura (lungs cavities)
• pericardium (around the heart)

Question 5

Connective tissue membrane?

Answer 5

Synovial membrane : lines fibrous capsules surrounding joints

Question 6

Integumentary system definition and constituents

Answer 6

Def: helps the body maintain a constant state of balanced internal conditions (homeostasis)

Const: skin, hair, nails, glands ( sweat or oily)

Question 7

Dermis constituents

Answer 7

Blood vessels

Receptors

Glands

Question 9

Receptors in dermis

Answer 9

Types of receptors:

• thermoreceptors
• meissners corpuscle (touch)
• nociceptor (pain)
• pacinian corpuscle (pressure)

Fct:
Work with other tissues to detect change in environment

Question 10

Glands in dermis

Answer 10

Enable body to maintain homeostasis (remove waste)

Help ensure body’s temperature remains the same

Sweat glands : emit moisture on skin surface + removes waste
Oil glands / Sebaceous glands : secrete lubricating liquid at base of hair follicle (activated during puberty)

Question 11

Skin function

Answer 11

Protection (from ext env)

• mechanical damage (keratinized cells)
• chemical damage (melanin’s uv protection+skin secretions)
• bacterial damage (macrophage of dermis + DNA
• thermal damage
• uv radiation
• desiccation (water loss)

Vitamin D synthesis

Aids in thermal regulation (sweat glands + hair)

Aids in excretion of urea and uric acid

Sensory receptors (nerves that receive msg)

Question 12

Fct of blood vessels in dermis

Answer 12

Provide dermis with blood

Enable the skin to grow and heal itself

Question 13

Skin structure

Answer 13

Epidermis

Dermis

Subcutaneous / hypodermis

Question 14

Epidermis definition

Answer 14

Outer thin layer of skin

Stratified squamous epithelium

Often keratinized
Keratin = fibrous protein that protects epidermis + connected by desmosomes
Arise from stratum basale and die along the way to surface

Question 15

Layers of epidermis

Answer 15

Stratum basale
-next to dermis
-cells undergo mitosis
-melanocytes (cells containing melanin)
Melanin= pigment that varies between yellow, brown and black
Amount of melanin produced depends on sun exposure or genes

Stratum spinosum

• 8 to 10 layers of keratinized cells connected by desmosomes
• cells phagocytose melanin progressively

Stratum granulosum
3 to 5 layers of cells connected by desmosomes

Stratum lucidum
ONLY IN THICK SKIN ( Palm of hands, feet, tip of fingertips)
2 to 3 layers of clear flat dead keratinocytes
(Cells start to detach and lose desmosomes)

Stratum corneum
Dead cells that protect the skin from water loss and gain

Question 16

Dermis definition

Answer 16

Region of connective tissue –> contain elastin + collagen

Contain sensory nerves

Question 17

Dermis layers

Answer 17

Papillary layer (upper)

• pain receptors
• capillary loops (from blood vessels)

Reticular layer (lower + bigger)

• blood vessels
• glands
• nerve receptors

Question 18

Hypodermis definition

Answer 18

NOT PART OF THE SKIN

Deep to dermis

Anchors skin to underpaying organs

Composed mostly of adipose tissue

Question 19

Normal skin color determinants

Answer 19

Melanin

• yellow, brown, black pigments
• in deepest layer of epidermis
• accumulate on keratinocyte nucleus forming shield that protects from uv

Carotene
-orange-yellow pigment from som vegetables

Hemoglobin

• red coloring from blood cells in dermis capillaries
• O2 content determines extent of coloring

Question 20

Appendages of skin

Answer 20

Sebaceous glands

Sweat glands

Hair

Nail

Question 21

Sebaceous glands

Answer 21

Produce oil :
Sebum 
-slows H2O loss
-lubricant for skin and hair
-kills bacteria

Connected to hair follicle
Activated during puberty

Question 22

Sweat glands

Answer 22

Widely distributed in skin

2 types
Eccrine : directly opens to pore on skin surface + abundant in thick skin
Apocrine : opens into hair follicle pore + less numerous than eccrine (secretion: water, salts, proteins, FA)

Question 23

Sweat and its function

Answer 23

Composition
Mostly H2O + some metabolic waste (+ FA and proteins in apocrine ONLY)

Function
Helps dissipate excess of heat
Excrete waste products
Acidic nature inhibits bacteria growth

Odor is from associated bacteria

Question 24

Hair definition

Answer 24

Def: flexible strands produced by hair follicle + consist of keratinized cells

Main regions: root -> shaft

Layers of keratinized cells (inner to outer)
Medulla -> cortex -> cuticle

Hair pigments made by melanocytes at root

Question 25

Structure of hair follicle

Answer 25

From epidermis to deep in the dermis ( sometimes into hypodermis) Deep end of hair follicle expanded -> hair bulb Which is surrounded by sensory nerve endings called : hair follicle receptor / root hair plexus + presence of papilla : supply nutrients to cells of hair bulb Around hair follicle (on walls) : outer connective tissue root sheath -> glossy membrane (basement membrane) -> inner epithelial root sheath Association with bundle of smooth muscle cells called arrector pili muscle (goose bumps)

Question 26

Nail

Answer 26

Def: scale like modification of epidermis -> form clear protective covering Made up of hard keratin (C sulfur) + lack of pigments Free edge of nail -> body of nail -> proximal nail fold

Question 27

Skin cancer

Answer 27

Basal cell carcinoma - least malignant - most common type of skin cancer - arise from stratum basale Squamous cell carcinoma - rapid growth + metastasizes to lymph nodes (ganglion of lymph. syst) if not removed early (early removal -> gd chance of cure) - arise from stratum spinosum Melanoma - most dangerous bcs highly metastatic + resistant to chemotherapy - cancer of melanocytes - metastasizes rapidly to lymph and blood vessels - detection by ABCDE rule

Question 28

ABCDE rule

Answer 28

``` Asymmetry : 2 sides of mole don't match Borders : irregular Color : variated Diameter : >6mm Evolving over time ``` Most dangerous form of melanoma : nodules melanoma has its own classification Elevated above skin surface Firm to the touch Growing

Question 29

Burns

Answer 29

Def: tissue damage inflicted by intense heat, electricity, radiation or chemicals -> denature cell proteins + cause cell death Most immediate threat : - dehydration - electrolyte imbalance due to fluid loss After 24hrs: threat becomes infection to the wound site

Question 30

Classification of burns

Answer 30

First degree: damage only to epidermis Second degree: injure epidermis + upper region of dermis Third degree: entire thickness of skin Critical if - over 25% of body has 2ndary - over 10% of body has 3rd Rules of nines: - way to determine the extend of burns - body divided into 11 areas - each area approx. 9%

Question 31

Developmental aspects of integumentary system

Answer 31

During embryonic formation: - ectoderm -> epidermis - mesoderm -> dermis + hypodermis End of 4th month: -dev of skin well formed During infancy and childhood: - skin thickens - more subcutaneous fat is deposited During adolescence: -sebaceous glands are activated -> skin + hair becomes oilier 20s and 30s: -skin reaches optimal appearance After that skin starts to show the effects of cumulative env exposures Old age: - rate of epidermal cell replacement slows - skin thins - lose collagen + fibers in dermis -> lose skin elasticity - skin more easily damaged (more prone to bruising and injuries)

Question 32

How skin changes at old age

Answer 32

Skin more easily damaged Epidermis thins Amount of collagen in dermis decreases (peptide chain weakened) Skin infections are more likely + repair of skin occurs more slowly Decrease in # of elastic fibers in dermis + loss of far from hypodermis -> skin sags and wrinkles Activity of sebaceous gland decreases -> skin becomes drier + decrease in blood supply to dermis --> poor ability to regulate body temp Number of functioning melanocytes decreases BUT in some areas (ex hands and face) melanocyte number increase -> age spots (Diff from freckles = increase in melanin production not in melanocyte number) Decrease in or lack of melanin production -> white or gray hair ! Skin more exposed to sunlight ages more rapidly (hands or face)