Integumentary sys

Question 1

integumentary system ?

Answer 1

skin and accessory structures (hair, glands, nails)
• covers entire body surface
• contains all four tissue types
• boundary between body and external environments

Question 2

Function of skin

Answer 2

• protection – against: abrasion, ultraviolet light exposure, dehydration, entry of microorganisms
• sensation – specialized sensory receptors detect temperature, pain, touch, pressure, proprioception (awareness of body position)
• temperature regulation - via changes in skin blood flow and sweat gland activity
• defence – contains cells of immune system
• vitamin D production
• excretion – removal of small amounts of waste products

Question 3

cutaneous membrane

Answer 3

contains the 2 major tissue layer
o epidermis = superficial epithelium
o dermis = underlying connective tissue
♣ accessory structures located in dermis and protrude through epidermis to surface

Question 4

hypodermis

Answer 4

o hypodermis (superficial fascia) = loose connective tissue

Question 5

epidermis

Answer 5

• stratified squamous epithelium (Fig 4.3)
• separated from dermis by basal lamina
• no blood vessels
• cells receive nutrients and excrete wastes products by diffusion
• 4 cells types: keratinocytes, melanocytes, Langerhans and Merkel cells

Question 6

keratinocytes

Answer 6

1. most numerous cell type
   o produce keratin = protein mixture that makes cell more durable
   o aids in ability to resist abrasion and reduce water loss
   o can obtain melanosomes (pigment granules) through phagocytosis of the tips of melanocytes

Question 7

stem cells of epidermis

Answer 7

o located in the deepest layer (stratum basale) of the epidermis continually undergo mitosis
♣ new cells push older cells toward the surface
♣ change shape and chemical composition as they move from deeper epidermal layers to surface

Question 8

keratinization

Answer 8

accumulation of keratin results in five epidermal layers (strata)

Question 9

stratum basale

Answer 9

♣ = deepest layer
• single layer of cuboidal stem cells that undergo mitosis
• firmly attached to basal lamina
• desmosomes (specialized cell junctions) hold keratinocytes together
• projects into dermis forming dermal ridges (Fig 4.5)
o ridge pattern determined genetically and forms unique fingerprints
o dermal projections toward epidermis = dermal papillae

Question 10

stratum spinosum

Answer 10

♣ 8-10 layers of many-sided cells
• flatten as they progress upward
• contain tonofibrils = bundles of protein filaments
act as cross braces, strengthening and supporting cell junctions

Question 11

stratum granulosum

Answer 11

♣ 2-5 layers of flattened, and elongated diamond-shaped cells that orient parallel to the surface

Question 12

callus

Answer 12

o localized thickening of skin

Question 13

forms large quantities of …. in stratum granulosum ?

Answer 13

keratohyalin
non-membrane bound protein granules, and keratin
- increase friction against skin stimulates synthesis

Question 14

lamellar bodies

Answer 14

• lipid-filled, membrane-bound organelles exocytosed

o coats cells and forms water-resistant layer but prevents diffusion of nutrients to more superficial layers

Question 15

stratum lucidum

Answer 15

♣ thin clear zone containing several layers of dead cells with indistinct borders
o only found in thick skin (Fig 4.4)
♣ areas subject to pressure or friction – palms of hands, soles of feet, and fingertips

Question 16

stratum corneum

Answer 16

few layers in thin skin to 25 or more layers of dead, dehydrated cells lacking nucleus and organelles in thick skin

Question 17

cornfield cells

Answer 17

overlapping dead overlapping cells with a hard protein envelope filled with keratin
part of stratum corner

Question 18

stratum corneum (shedding)

Answer 18

♣ cells shed in large groups or sheets due to connections (desmosomes) between cells
♣ dry – unsuitable for growth of many microorganisms

Question 19

how many days for new cells to arrive to surface

Answer 19

o akes 15-30 days to cell to move from stratum basale to surface
♣ cells stay at surface for about 2 weeks before being sloughed off

Question 20

psoriasis

Answer 20

• arises from malfunction of keratinization process
o stems cells in stratum basale unusually active
• affected areas have red bases and large scales of epidermis that are sloughed off

Question 21

melanocytes

Answer 21

1. found between keratinocytes within the two deepest layers of the epidermis
   o irregularly shaped with long processes
   o found in high concentration in freckles, moles, the nipples, areolae of the breasts
   o produce melanin = group of pigments responsible for skin, hair and eye colour
   ♣ packaged in vesicles called melanosomes
   ♣ provides protection against ultraviolet light

Question 22

langerhans cells

Answer 22

1. resident dendritic cells (immune cells) found in the skin

o have phagocytic ability and secretes substances that activate other cells of the immune system

Question 23

merkel cells

Answer 23

1. specialized epidermal cells associated with sensory nerve endings
   o responsible for detecting light touch and superficial pressure

Question 24

skin colour , combination of

Answer 24

o dermal blood flow – hemoglobin produces red tint
o thickness of stratum corneum - thick versus thin skin
o variable quantities of pigment

Question 25

carotene

Answer 25

♣ yellow/orange pigment that accumulates in keratinocytes | • becomes evident in dehydrated cells of stratum corneum

Question 26

melanin

Answer 26

♣ produced by melanocytes and passed via melanosomes to keratinocytes • genetic factors responsible for variation in skin colour among races o all races have approximately the same number of melanocytes ♣ differ in size, number, distribution and type of melanin within melanosomes o many genes responsible for skin colour

Question 27

albinism

Answer 27

o recessive genetic trait that results in lack of tyrosinase – the enzyme required to make melanin so lack pigment in skin, hair and irises of eyes

Question 28

exposure to UV light

Answer 28

o absorbs UV light o darkens the melanin already present in skin o stimulates melanin production

Question 29

hormones can increase what ?

Answer 29

• can increase melanin production during pregnancy or in disease states o estrogen and melanocyte-stimulating hormone in pregnant females

Question 30

Addisons disease

Answer 30

increased adrenocorticotropic hormones

Question 31

dermis

Answer 31

underlies the epidermis

Question 32

dermis : what is it ?

Answer 32

* connective tissue containing fibroblasts, a few adipocytes, and macrophages * collagen is the main connective tissue fiber but also contains elastin and reticular fibers * contains: some blood vessels, a variety of sensory nerve endings, hair follicles, smooth muscles, glands, and lymphatic vessels

Question 33

dermis is divided by :

Answer 33

• divided into two layers: papillary layer = loose connective tissue with thin fibers reticular layer = dense irregular connective tissue

Question 34

papillary layer

Answer 34

loose connective tissue with thin fibers o more superficial layer containing dermal papillae – projections that extend toward the epidermis o contains capillaries – smallest blood vessels that supply oxygen and nutrients to the epidermis o lie in parallel curving ridges in the thick skin of the hands and soles of the feet and shape the overlying epidermis ♣ increase friction and improve grip ♣ form unique fingerprints and footprints

Question 35

reticular layer

Answer 35

dense irregular connective tissue o main layer of the dermis o continuous with subcutaneous tissue o resists stretching in many directions o orientation of elastin and collagen fibers in some directions more than others ♣ produces tension (cleavage) lines (Fig 4.8) • important consideration when suturing cut or tear to reduce chance of gapping, infection, and scarring

Question 36

age, hormones and destructive effects of UV radiation reduce

Answer 36

o reduce thickness and flexibility of dermis

Question 37

stretch marks

Answer 37

♣ rinkles and creases formed when skin overstretched • elastin and collagen fibers in dermis rupture • skin does not recoil to original size leaving lines visible through the epidermis

Question 38

subcutaneous tissue

Answer 38

not part of the skin but skin rests on top of it • hypodermis or superficial fascia • loose connective tissue containing fibroblasts, adipocytes and macrophages • supplies blood vessels and nerves to skin • amount of adipose in the subcutaneous layer varies with age, sex and diet o stores approximately half the lipids of the body o insulates body o pads (protects) underlying structures o energy source