Laboratory Session 3

The skin

The integument from: http://faculty.irsc.edu/FACULTY/TFischer/AP1/skin.jpg

Layers of the SkinThe skin is divided into

three main layers:EpidermisDermisHypodermis/

Subcutaneous layer

Skin histology from: http://www.lab.anhb.uwa.edu.au/mb140/corepages/integumentary/Images/skthick0021he.jpg

The EpidermisThe epidermis of the skin is

composed of four/ five layers: Stratum basale – basal layer;

cells continuously divide to produce keratinocytes; 10 -25% of cell are melanocytes

Stratum spinosum – prickly layer

Stratum granulosum – granular layer

Stratum lucidum – clear layer; visible only in thick skin

Stratum corneum – horny layer; 20-30 layers thick of dead cells

Skin from: http://instruction.cvhs.okstate.edu/histology/HistologyReference/imagesco/skin2-3F.jpg

Pigmented Skin: Melanocytes

Thin skin from: http://protonbeam.org/histology/fieldTrip/thinSkin.jpg

Thin skinThin skin:

has a thin stratum corneum

is devoid of the stratum lucidum

covers most of the body surface

Thin skin from: http://php.med.unsw.edu.au/cellbiology/images/8/87/Skthin040he.jpg

Thick skin

The integument from: http://faculty.irsc.edu/FACULTY/TFischer/AP1/skin.jpg

Thick skin:has a thick stratum

corneumthe stratum lucidm

is presentcan be found on the

sole of your feet and the palm of your hands

The DermisTwo layers:

Papillary layer – of areolar connective tissue; contains dermal papillae

Reticular layer – of dense irregular connective tissue

Contains blood and lymphatic vessels, nerve fibers and accessory structures.

Thin skin from: http://protonbeam.org/histology/fieldTrip/thinSkin.jpg

NervesMeissner’s

corpusclelight touch receptor

Pacinian corpuscle deep pressure

receptorFree nerve endings

Nerves from: http://www.nku.edu/~dempseyd/MEISSNERS4.jpg and http://www.nku.edu/~dempseyd/PACINIAN4.jpg respectfully

HairHair :

is found all over our skin except the palms, soles, lips, nipples and parts of the genitalia

raises when the arrector pili m. contracts

Hair follicle from: http://missinglink.ucsf.edu/lm/IDS_101_histo_resource/images/172-1x-Hair_follicle_labelled.jpg

Sebaceous glandsSebaceous glands:

secrete sebumlubricates skin and

hairoccur all over the

body except palms and soles

Sebaceous gland from: http://www.lab.anhb.uwa.edu.au/mb140/corepages/integumentary/Images/sebaceous010tc.jpg

Sudoriferous glands

Sudoriferous glands:engage primarily in

thermoregulationare located all over

the bodyModified sweat

glands: mammary glands and ceruminous glands

Sweat gland from: http://www.nku.edu/~dempseyd/sweat%20gland%20good.jpg

Nails

Nails:are modifications of

the epidermisprotect the dorsal

surface of the distal part of our fingers and toes

are tools

Thin skin from: http://www.mc.vanderbilt.edu/histology/labmanual2002/labsection2/Integumentarysystem03_files/image020.jpg

Functions of the SkinProtectionTemperature regulationCutaneous sensationMetabolic functionBlood reservoirExcretion

Tissues and the Integument

•McConnell, T. H. and K. L. Hull. (2011) Human Form, human function: Essentials of Anatomy and Physiology. Baltimore, Lippincott Williams and Wilkins.•Cohen, B. J. and J. J. Taylor (2009). Memmler's Structure and Function of the Human Body. Baltimore, Lippincott Williams and Wilkins.•Marieb, E. N. and K. Hoehn (2010). Human Anatomy and Physiology. San Francisco, Benjamin Cummings.•Martini, F. H. (2006). Fundamentals of Anatomy and Physiology. San Francisco, Benjamin Cummings.