chapter 5- the integumentary system

Question 1

integumentary system

Answer 1

Covers entires outer surface of the body
Includes skin, hair, nails, various glands, and sensory receptors
Most visible organ of the body
Failing liver- skin turning yellow
Heart failure- pink\light red colour (blood is not being pumped efficiently)

Question 2

skin

Answer 2

Is the largest organ of the body by surface area (22 square feet) and weight (7% of average body weight)

Question 3

what are the functions of skin?

Answer 3

Protects the body against:
- dehydration (keratin layer)
- impact and friction injuries
- mold and bacterial invasion
- UV light damage (melanin production)

2. Acts as a receptor organ for sensory input
   
   • some sensors are sensitive to temp, touch,
3. Regulates body temp (capillary network and sweat glands)
   
   • capillary networks are found near the surface of the skin.
4. Secrets some wastes —> urea, salts and water
5. Synthesizes vitamin D from cholesterol molecules under action of sunlight
   
   • vit. D helps to absorb calcium. Which is needed for muscle contraction, nerve impulse

Question 4

structures of the skin

Answer 4

epidermis and dermis

Question 5

epidermis

Answer 5

outer, thinner layer

Question 6

dermis

Answer 6

inner, thicker layer
- vascularized (has direct blood flow)

Question 7

subcutaneous layer

Answer 7

The subcutaneous layer is NOT part of the skin.
also called hypodermis
Located underneath the dermis

Question 8

epidermis - detailed

Answer 8

composed of keratinized stratified squamous epithelium
Squamous epithelium: flattened irregular shaped cell (looks like a “fried egg”)
Stratified: multiple layers
Keratinized: made up of dead cells that help to protect the living cells underneath
Contains four major types of cells and five cell layers
Epidermis is renewed every 30 to 40 days
Basal cells: basal meaning bottom layer. They are constantly diving by mitosis. Constantly creating new cells.

Question 9

keratinocytes (90%)- epidermal cell type

Answer 9

produce keratin (fibrous protein) useful for protection
Protect skin and underlying tissues from heat, microbes and chemicals
Also produce lamellar granules: lipid rich secretion, fills spaces around and coats the same. Acts like a waterproofing agent. Helps to make sure we don’t lose water.
Surface cells die and only contain keratin (you can see)

Question 10

melanocytes (8%)- epidermal cell type

Answer 10

spider-shaped epithelial cells
Secrete and transfer the pigment melanin to keratinocytes
Found near basal surface and their cell projections extend between keratinocytes

Question 11

langerhas cells (or dendritic cells)- epidermal cell type

Answer 11

rise from red bone marrow and migrate to epidermis
Involved in immune responses

Question 12

Merkel cells (or tactile epithelial cells) - epidermal cell types

Answer 12

least numerous
Contact sensory neurons and function in touch sensations
Loaded deep in epidermis

Question 13

epidermal cell layers

Answer 13

Sole of feet, palms of hands thick skin have 5 layers, thin skin like on eyelids have 4 layers

Question 14

stratum basale

Answer 14

deepest layer, attached to dermis by wavy border
Single row of cuboidal/columnar keratinocytes
cuboidal cells look like a cube. Columnar cells look like a column.
Cells divide by mitosis
Contains melanocytes and Merkel cells

Question 15

stratum spinosum

Answer 15

8 to 10 layers of irregular-shaped keratinocytes
Cells contain many keratin filaments
Contains langerhans cells and projections of melanocytes (“spider arms”)
The cells are attached to one another very strongly.

Question 16

stratum granulosum

Answer 16

3 to 5 layers of flattened keratinocytes; nucleus and organelles disintegrate
Cells contain kerayphyalin (protein) and lamellar granules
Lamellar graniles release a lipid-rich, water repellent secretion
Transition layer between living cells below and dead cells above

Question 17

stratum lucidum

Answer 17

present only in thick skin (fingertips, palm and soles)
Consists of 3-5 layers of clear, flat, dead keratinocytes
Clear because they don’t have any organelles in them.

Question 18

stratum corner

Answer 18

25 to 30 layers of flat, dead keratinocytes containing keratin
Lamellar secretion (lipids) between the cells waterproofs this layer

Question 19

dermis

Answer 19

Connective tissue with fibroblasts, adipocytes, macrophages, mast cells, and embedded with fibres
Contains blood vessels, hair follicles, glands and nerves
Consist of two regions: papillary region and reticular region

Question 20

papillary region

Answer 20

upper 1/5 of dermis
Has dermal papillae at junction with epidermis
These papillae contain capillaries, free nerve endings and meissners corpuscles

Question 21

what is the purpose of fingerprints?

Answer 21

to create friction

Question 22

Reticular region

Answer 22

lower portion of dermis
Collagen fibres give skin strength and resiliency and bind water to keep skin hydrated
Elastic fibres provide strech-recoil properties
Stretch marks can appear if the skin is stetted too much.
Contains pacinian corpuscles (look like a onion cut in half)

Question 23

extensibility

Answer 23

collagen fives us the ability to strech

Question 24

elasticity

Answer 24

not only stretch but recoil

Question 25

Skin Colour

Answer 25

many pigments contribute to skin colour but the most important one is melanin Melanocytes produce melanin The number of melanocytes are about the same in all people but the amount of melanin produced differs Exposure of UV light increases melanin production Melanin absorbs UV radiation A mole is a benign localized overgrowth of melanocytes

Question 26

hair and hair follicles

Answer 26

Hair (pili) is present on most skin surfaces The hair shaft protrudes from the skin while the root is embedded in the skin Eyebrow, eyelash and nose hairs protect structures from foreign objects Keep dust out of eyes or nose Dogs and cats with fur are for thermal benefits Scalp hair protects from rays and sun Hair provide touch sensations in certain areas Light and touch sensation. Ex sitting outside and feel something on your arm (like a bug), you sense this because the bug is moving some of your hairs.

Question 27

hair shaft and root structures

Answer 27

Consist of three concentric rings of dead keratinized cells: Thin hair the medulla can be missing

Question 28

medulla

Answer 28

core of large cells. two to three rows of irregular shaped cells

Question 29

cortex

Answer 29

several layers of flattened cells makes up most of the hair

Question 30

Single layer of cells that overlap one another from below (like shingles on a roof)

Answer 30

Hair pigment is made by melanocytes at the base of the hair follicle and is transferred to cortex and medulla cells. Hair can become grey because of progressive decline of melanin production. White hair, there is no pigment

Question 31

hair follicle structure

Answer 31

The follicle is a tube-like in-pocketing of epidermis that extends into the dermis The base of the follicle is expanded as the hair bulb The hair papilla protrudes into the hair bulb and contains capillaries and a layer of cells called the matrix (matrix are the only ones still living and dividing.) Matrix cells divide mitotically as the hair grows Newly created cells move upwards and become dead keratinized cells

Question 32

growth stage

Answer 32

cells of matrix divide

Question 33

regression stage

Answer 33

matrix cells stop dividing

Question 34

resting stage

Answer 34

nothing happens

Question 35

what happens after the resting stage (give example of scalp hair)

Answer 35

the old hair root falls out of the follicle and a new hair begins to grow Ex. Scalp hair- has a growth stage from 2-6 years (single hair). Can grow 0.3 mm a day. Regression stage last 2-3 weeks (stops growing, starts to break down). After 3 months (nothing happens in these 3 months) you lose that strand. You lose 90 strands a day. Ex. Eyebrow hair- follicles are actively growing for 3-4 months, then goes to regression stages, stopes growing and falls out.

Question 36

Arrestor pili muscle

Answer 36

This is smooth muscle which attaches to the hair follicle and raises the hair Sensory nerve endings are also found around the hair bulb

Question 37

Sweat (sudoriferous) glands -- Eccrine sweat glands

Answer 37

simple coiled tubular glands emptying into a pore (eg. Palms, soles, forehead) Functional from birth Sweat is composed of stare, ions, urea, uric acid, ammonia, amino acids, glucose, and lactic acid (pH 4-6) Helps to regulate body temperature and has a small role in eliminating wastes Average person has 3 to 4 million sweat glands. Produce 600 ml of sweat

Question 38

Sweat (sudoriferous) glands -- apocrine sweat glands

Answer 38

are larger and empty into hair follicles Found in skin of axilla (arm pits) and groin Begin to function at puberty Secretion also contain lipids and proteins (organic components) When sweat glands on the skin, the bacteria living on skins breaks down lipids and protein, which then causes body odour.

Question 39

ceruminous glands

Answer 39

are modifies apocrine glands found in skin lining the external ear canal They secrete the sticky earwax (cerumen) Helps prevent foreign substances from entering ear

Question 40

sebaceous glands

Answer 40

simple branched alveolar glands connected to hair follicles Produce and secrete an oily substance called sebum Sebum softens and lubricates hair and skin to prevent hair from being brittle Also prevents dehydration of hair and skin Also inhibits growth of certain bacteria on the skin

Question 41

nails

Answer 41

are hard, keratinized epidermal cells More compacted, and there are other proteins that from cross link tens the deeper layer of epidermis from the nail bed under the nail Proximal portion of the nail bed is the nail matrix and is responsible for nail growth Nails functions to protect the distal phalanx (last bone on finger) and aid in grasping Nails on average grow 1mm

Question 42

free edge

Answer 42

extends over digit

Question 43

nail body

Answer 43

is the visible portion

Question 44

nail root

Answer 44

embedded in a fold of skin

Question 45

body temperature regulation

Answer 45

Homeostasis normal body temperature is 37 +/- 0.5 °C At normal body temp., conditions are optimal for enzymatic activity The body core (organs in skull, thoracic and abdominal cavities) temp. Is relatively constant The shell (skin) temp. Can fluctuate.body can use this to regulate body temp.

Question 46

vitamin d synthesis

Answer 46

vitamin D is actually a group of closely related compounds Synthesis of vitamin D begins in the skin with the formation of a precursor molecule, cholecalciferol It's required to increase calcium absorption from food.