mnsr 24 Flashcards

1
Q

the main functions of the skin

A

skin provides integument covering and has four main functions
1- protection : tough hide to protect against physical trauma , uv light by the melanin pigment, countinous unbroken line for microorganisms
2- thermoregulation: sweat and hair to provide insulation
3- metabolism: produces vitamin d used for the of calcium and phosphate metabolism
4- sensation: for pain, pressure, and temperature

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2
Q

the skin has been an area of

A

organ of sensory and nervous structure in asctreal metazoan.Embryologically the nervous system arise contiounsly from skin’s ectoderm.

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3
Q

Skin is the

A

largest organ ( 12.5 - 16.7 ) and is continuous w/ urigental tract ( penis/ vagina and urethera ) and digestive tract ( mouth and anus )

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4
Q

the two type of the skin

A

1- glabrous: thick and hairless e.g: soles of the feet and palms
2- hairy: thinner and most skin areas

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5
Q

The protective layer of the skin against phsycial chemical and microbial layer is

A

epidermis ( 0.06-0.1 mm thick )

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6
Q

The epidermis arises from

A

embryonic ectoderm

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7
Q

epidermis gives rise to

A

sweat glands
mammary glands
sebcoutnous glands

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8
Q

It predominantly consist of:

A

keranocytes arranged in stratified squamous epithelium starting at the basal membrane and moves outwards and becomes coreococytes in a process called: desquamation

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9
Q

The process of keranocytes maturing to corenocytes in the basal membrane is called

A

desquamation

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10
Q

The entire epidermal cycle takes

A

27 days

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11
Q

The layers of the epidermis from top to bottom

A

1- stratum corenuem: thick outer layer composed of flattened fused cells and composed mainly of keratin. Corneum is covered with oily secretion from the sebaceous gland called: sebum
2- straum lucidum: only thick skin, clear homogenous, layer without nuclei or organelle.
3- stratum granulosm: showing granules within the cells
4- stratum spinosum: aka prickle layer- growing skin showing early keratin synthesis
5- stratum basale ( basal layer): a proliferative layer of basophilic columnar or cuboidal cells

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12
Q

The color of the human skin is due to 3 factors
( skin pigmentation )

A

1- inherited yellow color from carotene at the subcutaneous fat
2- concentration of oxygenation of the heamoglobin in the dermal capalliries
3- Special branched cells scattered through the stratum basal the pigment in these cells is called: melanin and produces melanocytes. protects us against uv radiation.
A patch of dark pigment on the skin aka mole is called melanocytic nevus and small percentage of it will become cancerous aka melanoma

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13
Q

Keratinised structures

A
  • most mammals have: foot pads
  • higher primates have: friction ridges on palms and soles of the feet
  • the tip of the fingers have fingerprint: dermatoglyph
  • nails, claws , hooves are other kerantised structures
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14
Q

is an elongated rod of kernatised cells

A

hair shaft and grows from the root ( the hair bulb ) lying in the dermis layer

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15
Q

the hair bulb is the

A

base of a pit sunk in the dermis called : hair follicle

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16
Q

follicle cells is continuous with

A

epidermis

17
Q

during early —- the —- grows down into the —- to form —-

A
  • early fatal life
  • the epidermis
  • dermis
  • cellular shaft
18
Q

cells of the hair shaft are

A

dead kernatised epidermal cells expect the base where the growing germinal matrix exists

19
Q

the germinal matrix forms a

A

cap over a vascularised plug of dermal tissue called the dermal papilla

20
Q

the germinal matrix is connected to the

A

overlying epidermis by the cellular external root sheath and the entire structure is called: pilosebaceous unit

21
Q

the proliferation in the cells in the germinal matrix produces

A

hair growth
- initially these cells r pushed up the centre of the epidermal down growth
- as the move further from the papilla blood supply they become kerantized and die
- initial cells transform into: hair cortex w a single outer layer of hair cuticle

22
Q

the hair follicle consist of ( check the structure in the slides )

A
  • medulla ( seldom seen)
  • cortex( kernatised cells )
  • cuticle( single layer of overlapping kernatised cells )
  • internal root sheath: produces further division of germinal matrix cells which pushes up between external root sheath and the hair follicle
23
Q

the hair shaft is help in position from

A

external and internal root sheath ( ERS AND ERS )

24
Q

Hair grows in a

A

cyclical basis

25
Q

growth phase in young adult is

A

~3 years and 85% of scalp hair is in growth phase followed by the degeneration of the follicle.

26
Q

the sebaceous gland is derived from

A

ERS and produces sebum into the follicle that has mild fungistatic and bacteriostatic action

27
Q

hair position can be elevated bt

A

arrestor pillus muscle attached to the hair bulb and the epidermis

28
Q

Other glands in the skin

A

1- sebaceous gland ( oil)
2- sudoriferous gland ( sweat )
3- ceruminous ( ear wax )
40 mammary gland

29
Q

is connected to the hair follicle and forms the pilosebaceous unit

A

-sebaceous gland that produces sebum to protect the skin and the hair.
- releases secretions via holocrine mechanisms into the hair follicle shaft
- located over most of he body/skin expect palms and soles of the feet

30
Q

The 2 types of sudoriferous ( sweat) gland

A

1- apocrine - ducts open in the hair follicles asL armpits, pubic region, areola of the breast
2- eccrine: ducts terminate as sweat pores at the epidermis. Throughout the skin except lips,nailbeds, and eardrums
- This gland is coiled tubular gland , secretory portion lines fascia within a duct up to the skin surface , secretes sweat for thermoregulation

31
Q

ceruminous glands are

A

ducts open either directly onto the surface of the external auditory ear canal or into the duct of sebaceous glands.
secretion combines w sebum associated w sebcaous gland to from cerumen aka ear wax
- to protect the ear from foreign materials as dust

32
Q

are highly modified derivatives of sweat glands

A

mamamry glands and the milk production is under hormonal control.
Mammary glands develop by the thickening of the epidermis - the milk lines - in the abdominal walls

33
Q

dermis is prodmintly composed of

A

fibroblast which secretes and organises large amount of ECM.
ECM is mainly fibrillar collagen as type 1,111, v, elastin

34
Q

papillary dermis is

A

wish in vasculature and have nerve ending, thermo/cryoreceptors

35
Q

reticular dermis is

A
  • thicker of the 2 substrata
  • dense connective tissue contains elastin network and proteoglycan
  • provides structural support for the skin
36
Q

dermis is derived from —- and is — in thickness

A

mesoderm and is 2 mm thick

37
Q

dermis is composed of

A
  • collegen , elastin fibers ( strength and elasticity)
  • blood vessels ( thermoregulation , immune function
  • nerves
  • fibroblast - forms collegen and elastin
  • mast cells - inflammatory responses to pathogens and injuries
  • lymphatics
  • epedrimal appendages
  • glycosaminoglycan; hyaluronic acid, chondotrion surfaces and glycoprotein ( retains h20 and provides moisture to the epidermis )