ANATOMY AND PHYSIOLOGY OF SKIN

1. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
Learning outcomes of the lab exercises:
1. Locate on microscope slides and classroom models the major structures of the skin.
2. Describe the major functions of the skin.
3. Distinguish the locations and components of the epidermis, dermis and hypodermis.
4. Identify and sketch regions of the skin and associated accessory structures such as hair and
glands that were observed on the microscope slides.
"Although you may not typically think of the skin as an organ, it is in fact made of tissues that work
together as a single structure to perform unique and critical functions. The skin and its accessory
structures make up the integumentary system, which provides the body with overall protection... It also
has numerous sensory, and autonomic and sympathetic nerve fibers ensuring communication to and
from the brain."
OpenStax A&P pg. 180
I. SKIN AND ITS TISSUES (Cutaneous Membrane)
A. General Structure:
1. Two distinct regions or layers compose the skin:
a. Epidermis = outermost layer;
o keratinized stratified squamous ET.
b. Dermis = inner layer;
o glandular epithelium (sweat, sebaceous glands),
o dense irregular CT (collagen),
o smooth muscle tissue (arrector pili muscles),
o nervous tissue (Meissner's & Pacinian Corpuscles), and
o hair follicles and blood vessels
2. Subcutaneous layer = adipose tissue; also called hypodermis

2. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
OpenStax A&P Fig. 5.2 Layers of the Skin
B. Skin Functions
1. Protection:
o Physical barrier
▪ from water loss; injury; chemicals and microorganisms.
o Chemical barrier
▪ pH or 5-6; prevents microorganism growth
o Biological barrier
▪ Langerhan’s cells (epidermis)
▪ Macrophages and mast cells (dermis)
2. Excretion (minimal, most through kidneys!):
o urea; uric acid.
3. Regulation of body temperature
4. Cutaneous Sensation:
o Light touch detection = Meissner's Corpuscles;
o Pressure detection = Pacinian Corpuscles;
5. Vitamin D Synthesis:
o UV rays in sunlight activate its synthesis;
o Vitamin D is required for bone homeostasis.
6. Blood Reservoir:
o The dermis houses about 10% of the body's blood vessels.
o Skin only requires 1-2% of the body’s blood
7. Immunity:
o Langerhan’s cells (macrophages);
C. Epidermis:

3. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
Fig. 5.5 Layers of the Skin
1. Structure = keratinized stratified squamous epithelium;
a. Four distinct layers
1. Stratum corneum = outermost layer.
o composed of dead epithelial cells filled with the protein
keratin;
*** Stratum lucidum = translucent layer cells separating s. corneum
from s. granulosum. This extra layer is only found in the thick skin
of the soles & palms;
2. Stratum granulosum is composed of 3-5 layers of flattened
granular cells (filled with keratin granules);
3. Stratum spinosum is composed of many layers of spiky cells with
large nuclei;
4. Stratum basale (germinativum)= innermost layer;
o directly above basement membrane;
o mainly consists of keratinocytes, then main cell type in
the epidermis, in this layer they are arranged in a single
row, very active in mitosis
o contains melanocytes which are specialized cells that
produce the pigment melanin.
2. Main Function = Protection (keratin):
a. prevents moisture loss (waterproof); injury by penetration or entry of
microorganisms / chemicals
b. Pigment = Melanin: determines skin color:
o produced by melanocytes in stratum basale
D. Dermis:
1. Structure= inner layer of skin; binds epidermis to tissues
a. two distinct layers:

4. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
1. papillary layer (20%) is below epidermis:
o composed of loose areolar CT;
o surface forms dermal papillae
(finger-like projections into the epidermis) that form
fingerprints in thick skin
o Meissner's Corpuscles ( receptors for light touch).
2. reticular layer (80%) = dense irregular CT;
o collagen fibers, elastic fibers, and reticular fibers
o Pacinian corpuscles – deep pressure receptors
E. Subcutaneous Layer (hypodermis) = beneath skin.
1. Structure = adipose tissue & blood vessels;
2. Function = insulation.
Fig. 5.7 Layers of the Dermis
II. ACCESSORY ORGANS OF THE SKIN (Epidermal Derivatives)
A. Hair Follicles:
1. Structure:
o root in dermis, follicle throughout dermis, hair shaft in epidermis.
2. Arrector Pili Muscle = smooth muscle associated with every hair follicle.
o hair pulled up ("goose bumps") when frightened or cold.

5. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
Fig. 5.11 Hair
B. Nails:
1. Epithelium undergoing keratinization (active mitosis in lunula).
2. Functions: manipulation and protection of digit ends.
Fig. 5.13 Nails
C. Sebaceous Glands:
1. holocrine gland (simple cuboidal epithelium);
2. associated with every hair follicle;
3. Secretion (holocrine) = sebum (i.e. oil).

6. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
REVIEW ACTIVITY - INTEGUMENTARY STRUCTURES FOR LABELING
WORD BANK
arrector pili muscle merocrine (sweat) gland
dermis Pacinian corpuscle
epidermis papillary layer of dermis
epithelial sheath reticular layer of dermis
hair follicle sebaceous (oil) gland
hair papillae/bulb
hair shaft stratum basale
hypodermis stratum corneum
Meissner’s corpuscle stratum granulosum
melanocytes stratum lucidum*

7. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
sensory receptor (nerve) stratum spinosum
Lab Review Questions
1. What substance begins its manufacture in the skin by exposure to sunlight (but is not a secretion) to
play a role elsewhere in the body?
2. List 4 types of sensory receptors found in the skin and their functions.
3. What cells help darken the skin? In which layer of the epidermis are they found?
4. How does the skin help in regulating body temperature? (Describe two mechanisms)
Multiple Choice Questions
1. Which of the following is NOT a function of the integumentary system?
A. Excretion
B. Temperature regulation
C. Production of blood cells
D. Protection
2. What material gives the epidermis the ability to resist abrasion and reduce water loss?
A. Keratin
B. Melanin
C. Carotene
D. Dermal papillae
3. What structures of the epidermis are responsible for detecting light touch ?
A. Langerhans cells
B. Merkel cells
C. Keratinocytes
D. Melanocyte cells
4. Which is the correct sequence of the strata of the epidermis from deep to superficial?
1. stratum lucidum 2. stratum basale 3. stratum corneum 4. stratum granulosum 5. stratum spinosum
A. 3, 1, 4, 5, 2
B. 1, 2, 3, 4, 5
C. 2, 5, 4, 1, 3
D. 4, 2, 3, 1, 5
5. Having 1 - 2 layers of cells closest to the basement membrane and rapid mitosis is a feature of the :

8. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
A. Stratum lucidum
B. Stratum basale
C. Stratum corneum
D. Stratum granulosum
E. Stratum spinosum
6. Having 8 - 10 layers of cells filled with keratin fibers and a "prickle" appearance is feature of the :
A. Stratum lucidum
B. Stratum basale
C. Stratum corneum
D. Stratum granulosum
E. Stratum spinosum
7. This layer is found ONLY in thick skin :
A. Stratum lucidum
B. Stratum basale
C. Stratum corneum
D. Stratum granulosum
E. Stratum spinosum
8. The most superficial layer of skin, having 25 or more layers of dead squamous cells with keratin :
A. Stratum lucidum
B. Stratum basale
C. Stratum corneum
D. Stratum granulosum
E. Stratum spinosum
9. Skin pigment is produced by cells called :
A. Melanocytes
B. Keratinocytes
C. Adipocyte
D. Langerhans cells
10. The hypodermis is mostly :
A. Protein
B. Collagen
C. Glycogen
D. Adipose tissue

9. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
Problem Solving Activity
The following problem solving assessment is presented in a multiple-choice format. Each choice
should be considered individually and an argument should be written for accepting or rejecting it. Since
the problem has one best answer, there should be one argument for acceptance and four for rejection.
For each response, you must first state whether you are accepting or rejecting that statement. Then,
you must write a detailed explanation why you accept or reject each of the choices.
PROBLEM:
There are several types of epithelial tissues found in or on the body. One type is called keratinized
stratified squamous epithelium. Which of the following would be correct about this particular type of
epithelium?
A. It lines most of the digestive tract.
B. It forms the walls of the air sacs of the lungs.
C. It forms the outermost layer of the skin.
D. It comprises the endothelium and mesothelium.

10. CVMU
INDUKAKA IPCOWALA COLLEGE OF PHARMACY
Integumentary System
MRS.RISHITA D PATEL HAP-I
E. It forms the lining of the kidney tubules.