Module 4 - Skin & Integumentary System

Question 1

Define a membrane

Answer 1

A flat sheet of tissue that covers or lines part of the body

Question 2

What 2 layers does a membrane consist of?

Answer 2

An epithelial later

And

A connective tissue layer

Question 3

What are the 4 types of membranes?

Answer 3

Mucous

Serous

Cutaneous

Synovial

Question 4

What is the function of a mucus membrane?

Answer 4

Mucous membranes line surfaces that open to the outside

I.e the lining of the digestive, respiratory, reproductive and urinary tracts

Question 5

What is the purpose of the mucous membrane and how does it work?

Answer 5

Cells of the epithelial layer secrete mucous and fluids to:

• Prevent the surface from drying out
• Lubricate (reduce friction)
• Facilitate absorption and secretion

The connective tissue layer

• composed of areolar connective tissue
• binds the epithelium to underlying structures

Question 6

What are serous membranes? What are the 2 parts?

Answer 6

•line body cavities that do not open to the outside and cover organs that lie within the cavity

Two parts:

1. parietal layer(covers the body cavity)
2. visceral layer(covers the organs)

Question 7

What are serous membranes composed of?

Answer 7

The epithelial layer:
–composed of simple squamous epithelium
–secretes serous fluid (reduces friction during organ movement)

The connective tissue layer:
–formed by areolar connective tissue

Question 8

What are the 3 different types of serous membranes?

Answer 8

Types of serous membranes include:

1.pleura:
–line pleural cavities and covers lungs
2.peritoneum:
–lines the abdominal cavity and covers abdominal organs
3.pericardium:
–lines the pericardial cavity and covers heart

Each has parietal and visceral layers

Question 9

What 2 key parts are the integumentary system made up of?

Answer 9

1. cutaneous membrane (= skin)

2. accessory glands and structures

Question 10

What are the two layers of the skin? What is underneath that?

Answer 10

1.epidermis: superficial epithelial tissue layer 2.dermis: thicker underlying connective tissue layer

the hypodermis= subcutaneous layer
–composed of areolar and adipose CT
–not part of skin
- attaches skin to underlying tissues and organs
–contains fat storage and large blood vessels supplying the skin

Question 11

What are the 5 functions of the skin?

Answer 11

1. Body temperature regulation (via sweating and changes in blood flow)
2. Protection of underlying tissues and organs (from UV light, microorganism entry, abrasion)
3. Cutaneous sensations (touch, pain, temperature) 4.Excretion of salts, water, and organic wastes 5.Synthesis of vitamin D

Question 12

What kind of cells are the epidermis made of? Is it vascular or avascular?

Answer 12

• stratified squamous epithelium

* avascular (nutrients and oxygen diffuse from capillaries in the dermis)

Question 13

What are the 4 epidermis cell types?

Answer 13

1. keratinocytes
2. melanocytes
3. Langerhans cells
4. Merkel cells

Question 14

Keratinocytes make up what percentage of cells in the epidermis?

Answer 14

90 percent

Question 15

What do keratinocytes produce?

Answer 15

•produce keratin
–a tough, fibrous protein
–strengthens and protects the skin

•produce granules that release a lipid-rich substance
–repels water to prevent the loss of fluid from the body through the skin

Question 16

Where are keratinocytes found?

Answer 16

In the epidermis

Question 17

Where are melanocytes found?

Answer 17

found in the deepest epidermal layer (stratum basale)

Question 18

What do melanocytes produce?

Answer 18

produce melanin
–a yellow-brown or black pigment
–contributes to skin colour
–absorbs UV light (protects keratinocytes from DNA damage which leads to cancer)

**extensions of the cytoplasm deliver melanin to the keratinocytes **

Question 19

What are langerhans cells and what is their purpose?

Answer 19

( Intraepidermal macrophages )

• phagocytic cells
• part of immune response against microorganisms that enter the skin
• easily damaged by UV light

Question 20

What are merkel cells and what is their purpose?

Answer 20

( Tactile epithelial cells )

• cells that contact specialized sensory nerve endings called tactile (Merkel) discs
• detect different aspects of touchsensations

Question 21

What are the 5 epidermis cell layers?

Answer 21

•Cell layers (called stratum):

1. corneum
2. lucidum
3. granulosum
4. spinosum
5. basale

Question 22

Which layer is stratum basale? What kind of cell structure does it have? What kind of cells is it composed of?

Answer 22

• deepest layer
• single row of cuboidalor columnar cells
• contains Merkel cells, melanocytes and stem cells
• stem cells–continually divide (by mitosis) to produce new keratinocytes –as new cells are produced, older cells are pushed to the surface

Question 23

What is stratum spinosum? How many layers of keratinocytes is it composed of? How is it produced? What are they bound by? What kind of cells does it contain?

Answer 23

• 8 - 10 layers of keratinocytes
• produced by the division of stem cells of the basal layer
• packed closely together and bound by desmosomes
• contains Langerhans cells

Question 24

What is stratum granulosum? How many layers of keratinocytes is it composed of? What do the cells contain? What happens to the cells once keratin is produced?

Answer 24

•3 to 5 layers of keratinocytes
•cells contain keratin and lipid-rich granules
•cells die once keratin is produced
–cells are flattened
–nuclei and organelles degenerate

Question 25

What is stratum lucidum? How many layers of FLATTENED, DEAD keratinocytes is it composed of? What are the cells filled with? Where is this layer found?

Answer 25

* 3-5 layers of flattened, dead keratinocytes * cells are filled with keratin * this layer is only found thick skin (i.e. fingertips, palms and sole of foot)

Question 26

What is stratum corneum? How many layers of flattened, dead keratinocytes is it composed of? What happens to the cells continuously? How long does it take for a cell to move from the stratum basale to the stratum corneum? What is the function of stratum corneum?

Answer 26

* exposed layer * 25 – 30 layers of flattened, dead keratinocytes * cells are continuously shed and replaced **it takes 15 to 30 days for a cell to move from the stratum basale to the stratum corneum** •multiple layers of keratin-filled cells prevent water loss and provide protection from injury and microbes

Question 27

What are the 3 conditions that affect the epidermis?

Answer 27

* a callous is an abnormal thickening of the stratum corneum due to friction (protective) * first degree burns affect only the epidermis * skin cancer can affect a number of epidermal cell types (basal cells, squamous cells, melanocytes)

Question 28

What is the dermis?

Answer 28

= connective tissue layer below the epidermis, containing collagen and elastic fibres

Question 29

What are the 2 distinct regions of the dermis?

Answer 29

1. superficial | 2. deep

Question 30

What is the superficial dermis? What is it composed of? What does it form?

Answer 30

* upper 1/5 of the dermis * composed of areolar connective tissue containing elastic fibers * forms fingerlike-projections called dermal papillae surface area for attachment between the epidermis and dermis

Question 31

What is the deep dermis? What kind of cells does it contain? What kind of tissue is it composed of?

Answer 31

``` •deep 4/5 of the dermis •contains adipose cells, larger blood vessels, nerves, hair follicles, oil glands and sweat glands •composed of dense irregular connective tissue containing both collagen and elastic fibers for: –strength –extensibility (ability to stretch) –elasticity (ability to recoil) ```

Question 32

What are the 2 conditions that affect the deep dermis?

Answer 32

* wrinkles–caused by reduced collagen production and wear and tear of elastic fibres within the dermis layer * stretch marks–excessive stretching (i.e. pregnancy) causes small tears in the dermis

Question 33

What are the 3 factors that determine skin colour? How?

Answer 33

1.melanin: –dark pigment from melanocytes –the # of melanocytes is the same in most people but the amount of melanin produced differs between skin colours –What is albinism? 2.carotene: –yellow-orange pigment needed for vision –accumulates in the stratum corneum and fatty areas of the skin 3. hemoglobin: –oxygen-carrying pigment of RBCs –blood appears red when hemoglobin is oxygenated –increase blood flow to capillaries of the skin, skin turns red (i.e. blushing)

Question 34

What are the 3 accessory structures to the skin and where do they originate?

Answer 34

``` •originate in the dermis •extend through the epidermis to the skin surface •accessory structures of the skin include: 1.hair 2.glands (oil, sweat, wax) 3.nails ```

Question 35

What is hair? Where is it found? What are its 4 functions?

Answer 35

•present on most skin surfaces, except lips, palms, soles, and portions of the external genitalia •Functions: 1. protection (from injury, UV light) 2. insulation 3. guards openings (i.e. ears, eyes, nose) 4. detect light touch

Question 36

What is the hair structure composed of? What are the 2 main parts?

Answer 36

•composed of a thread of dead, keratinized cells •Two parts: 1. shaft (projects above the skin surface) 2. root (penetrates into the dermis)

Question 37

What is a hair follicle? What 2 layers is it formed by? What is it surrounded by?

Answer 37

= surrounds the hair root •formed by 2 layers of epidermal cells that penetrate into the dermis, internal and external root sheaths •surrounded by dense connective tissue

Question 38

What is a hair bulb? What 2 parts does it contain?

Answer 38

= the enlarged base of each follicle Contains: 1. papilla–blood vessels 2. matrix–cells divide to produce hair –melanocytes (determine hair colour)

Question 39

What are the 2 other hair structures? What are their functions?

Answer 39

•hair root plexus: –hair follicle nerve endings that are sensitive to touch •arrector pili muscle: –extends from the upper dermis to the hair follicle –contracts when frightened or cold (‘goose bumps’)

Question 40

What are the 3 skin glands?

Answer 40

•Glands found in the skin include: 1. sebaceous (oil) 2. sudoriferous (sweat) 3. ceruminous (wax)

Question 41

What are sebaceous glands? Where do you find them? What do they secrete? What are the 3 functions ?

Answer 41

lie in the dermis and open: 1.into the hair follicle 2 .onto the skin surface * secrete an oily substance called sebum * functions: 1. keeps hair and skin from drying out 2. keeps skin soft 3. inhibits growth of some bacteria •Where don’t you find oil glands? palms of hands and soles of feet

Question 42

What is the condition that affects sebaceous glands?

Answer 42

•pimples= enlarged sebaceous glands caused by the accumulation of sebum and bacteria –sebum provides nutrition for bacteria

Question 43

What are sudiferous glands? What do they produce? Where are they found? What is their function?

Answer 43

* produce sweat which contains mainly water and salts (NaCl) * secretory cells lie deep in the dermis or hypodermis * sweat is released into ducts * functions to regulate body temperature (cooling)

Question 44

What are the two types of sweat glands? What are their functions? Where are they found?

Answer 44

1.eccrine: –most common –sweat ducts open directly onto the skin surface –found mainly in the skin of the forehead, palms, and soles 2. apocrine: –sweat ducts open into a hair follicle –mainly found in the armpit, groin and areola of breast –start functioning at puberty –stimulated by stress and excitement

Question 45

What are ceruminous glands? Where are they found? What do they produce? What is their function?

Answer 45

* found in the external auditory canal (outer ear canal) * produce cerumen (earwax) * cerumen and hair = protect the eardrum by forming a sticky barrier against foreign bodies

Question 46

What are nails and what do they consist of?

Answer 46

•plates of tightly packed, hard, keratinized cells •Consists of: –nail body (pink due to underlying blood vessels) –free edge (portion that extends past the finger or toe) –nail root (portion of nail that is not visible) •nail matrix: cells of the epidermis transform into nail cells (1 mm/week) •lunula: thickend region of the underlying epidermis (blood vessels not visible) •cuticle: consists of stratum corneum