skin anatomy and physiology. also known as a integumentary system, largest sense organ. contains different layers any and different types of cells in each layer.

1. • Sree divya Katuru
Mpharm. pharmacology
Reg.pharmacist (TSPCI)
Skin (tactile)
(integumentary
system)

2. INTRODUCTION
The skin also known as cutaneous membrane or integument,
covers the external surface of the body and protects the
interior of the body.
It is a sensory organ which is a largest organ of the body in
both surface area and weight.
It is continuous with mucous membrane of body orifices.
It has an average thickness of 1 to 2 mm.
with a pH range of 4 to 5.6.
The renewal of skin takes place in 28 to 50 days.

3. STRUCTURE OF THE SKIN There
are two major classes of the skin:
 1. Hirsute – thin, hairy skin
which covers grater part of the
body.
2. Glabrous – which covers the
surfaces of palms, soles and flexor
surfaces of the digits.
3 layers of skin
a. epidermis
b. dermis
c. hypodermis

5. EPIDERMIS
-superficial , thinner layer -epithelial tissue
-no blood vessels or nerve endings
-but its deeper layers ->interstitial fluid from the dermis
-supply oxygen and drains away as lymph.
DERMIS
-deeper, thicker -connective tissue -vascular -nutritive
HYPODERMIS
-deep to dermis -not skin -thin layer of areolar and
adipose tissue -attatches to underlying fascia (muscle&bone)
-stores fat -large blood vessls -nerve endings
=>pacinian (lamellated)corposc. => senses pressure

6. EPIDERMIS – keratinised stratified squamous
a. Stratum corneum = many layers of flat, dead, scale like cells full of
keratin
b.Stratum lucidum = one or two layers of dying cells
c. Stratum Granulosum = Three or four layers of skin; actively
synthesizing protein keratin
d. Stratum spinosum = three or four layers of cells with some cell
division
e. Stratum Basale = Single row of dividing cells (strt. germinativum)

7. • 90% of epiderm. , 4
to 5 layers
• Produce keratin &
• Lamellar granules
keratinocytes
• Melanin pigment
• Protect nuclear DNA
of keratinocytes from
damage by UV
melanocytes
• From red bone marr.
• Pariciptn. In immune
response
• Helps other cells of
immunity to recognise
Langerhans
cells/ epidermal
dendritic cells
• Least num. of epiderm.
• Deepest layer in
epidermis
• Contact with merkel
disc
Merkel cells
4 principle types of cells of epidermis
keratin
Lamellar
granules
Tough, fibrous,
protectn.
Release water repellant
sealant
- entry of
foriegn part.
Merkel disc =>flattened
process of a sensory neuron
Merkel
disc
Merkel
cells
Sense of touch
(tactile)

8. (ii) DERMIS
• Contains many types of sensory receptors for touch ,
pressure, vibration, pain , temperature etc ..
• Papillary layer is folded into ridges which extend into upper
epidermal layer. The exposed ridges form congenital
patterns called finger prints and foot prints
-dermal papillae => contains capillary loops( bld.ves.)
=> also messiner corpuscles=> tactile sense
=> free nerve endings => warm, cool,
pain,tickiling,itching
• Reticular layer contains collagen Elastic ,reticular
fibers,hair follicles, nerve endings and macrophages
=> provide extensibility and elasticity
Dermatoglyphics = study of patern of fingerprints

10. . In control of temp.reg. centr of hypothalamus

11. Alopecia: baldness- normal hair is replaced by thin and transperent hair

13. •Functions of skin
1.Protection

14. 2. Excretion & absorption
-small role in excrt. & abs.
-SWEAT => water &heat , also elim. ofsalts, co2, ammonia & urea
Though abs.=>negligible, certain lipid solubles penetrate skin.
eg: vit- A, D, E, K
•certain drugs through adhesive patches
•Gases –o2 , co2
•Toxic mater. –acetone, ccl4
•Heavy metals- lead, mercury, arsenic
•Poison ivy, poison oak
3.Cutaneous sensation
Tactile through sensory recep.
Thermal
pain
Nerve ending,
corpusc. , hair
root plexus
Cerebral cortex

15. 4. Blood-nutrient reservoir
dermis – extensive bood flow (8-10% of total bl.flow) – blood
reservoir
more blood=> more nutrient supply and storage
hypodermis=> adipose tissue => fat storage
5. Formation of vit-D
7-dehydrocholestrol u.v from vit-D precursor
(in skin) sunlight enzymes in liver
& kidney
vit-D
boost immunity &reduce inflamation formation
& maintanence
of bone

16. 6. Thermo regulation
homeostatic reg. – Helps to maintain homeostasis through
fluid and electrolyte balance
2 ways a. liberation of sweat
b. adjust. Blood flow
a) envi. temp. rise or heat by exercise sweat prod.(eccrine )
evaporation of sweat frm skin  lowering of body temp.
b) B.V in dermis  dilate  increses bld.fl  promotes heat
loss

17. Addt.note:
hypothermia (low body temp.):
present when core temp. is <35°c
If <32°c  ve feed bck will fail.
shivering replaced by muscle rigidity &
cramps
vasoconstriction
B.P, pulse, resp. decreases
 Mental conf. &disorientatn.
Death  temp. <25°c
Extreme aged indivi.  more prone

18. Q&A

19. • List the different sense organs and explain the
anatomy and physiology of eye-5
• List the different sense organs and explain the
anatomy and physiology of ear-5
• Describe the anatomical features of tongue-5
• Discuss the structure and functions of skin in brief.5
• Draw a neat labeled diagram of section of eye. And
add a note on physiology of vision.
• Write about the functions of skin 2

20. • Anatomy of Eye-5
• List the different types of taste buds with functions-2
• Explain the anatomy and physiology of Ear -5+5
• Describe the anatomical features of ear with a neat
labeled diagram and discuss the physiology of hearing.
-5+5
• Mention different muscles of eye and their functions-2
• Describe the anatomy and physiology of tongue with
labelled diagrams -5

21. • List out the bones of orbit.-2
• Write about functions of skin-5