Integumentary system

9 - Integumentary system

Basic characteristics

• Relativley waterproof

• washable

• stretchable

• Invisibly repair small cuts, scratches, & burns

• Guaranteed to last a lifetime (with reasonable care)

• Thick skin

Components of the integumentary system

• Skin

• Skin derivatives - Hair, nails, oil glands, sweat glands

What are the main functions of the skin?

• protection

• Physical barrier from enviornmental factors

• Repair

• Thermoregulation

• sensation

• Vitamin D synthesis

What are the 2 layers of the skin?

• Epidermis

• Dermis

What is the epidermis composed of?

• Tightly packed epithelial cells that line the surface of the skin

• 4-5 layers

• Avascular (no blood vessels)

Layers of the epidermis (Thick Skin)

• Stratum corneum

• Stratum lucidum ‘

• Stratum granulosum

• Stratum spinosum

• Stratum basale

Where is thick skin found on the body?

Only on the palms of the hands & soles of feet

Layers of the epidermis (thin skin)

• Stratum corneum

• Stratum granulosum

• Stratum spinosum

• Stratum basale

Stratum germinative (basale)

• Deepest layer

  Function: Form a bond between the epidermis and dermis

What type of cell junction anchors the stratum Germinative to the basal lamina?

Hemidesmosomes

What are the “layers” of the epidermis?

• Dermal papillae

• Epidermal ridges

Dermal papillae

Increase the surface area of the basal lamina (basal layer); strengthen attachment between epidermis and dermis

Epidermal ridges

Ridges of the epidermis that form fingerprints

What cells are located in the epidermis?

• Melanocytes

• Merkel cells

Melanocytes

Synthesize melanin (pigment)

Merkle cell

detect light touch (triggers nervous system)

Stratum Spinosum (spiny layer)

Contains 8-10 layers of keratinocytes

How are the keratinocytes in the stratum spinosum bound together?

By desmosomes (cell junctions)

Why do the cells in the stratum spinosum continue to divide?

To increase thickness of the epithelium

What are the cells of the stratum spinosum

• Keratinocytes

• Langerhan cells

Langerhan cells

Immune cells; defend against foreign invaders that deep into the skin

Stratum Granulosum (Grainy layer)

• Continue producing: Keratinocytes

• Start producing: keratohyalin

  Granules create a “grainy” look

Keratohyalin

Promotes dehydration of the cells

Stratum Lucidum (Thick skin)

• Clear, glossy layer

• Keratinocytes surrounded in eleidin

Eleidin

Clear protein that surrounds keratinocytes

Stratum Corneum (horny layer)

• Layer composed of dead, keratinized cells

• Resistant to abrasions, cut, and water loss

What is Keratinization?

The process of forming a layer of dead, protective cells filled with keratin

List all the cells of the epidermis

• Keratinocytes

• melanocytes

• Merkel cells

• Langerhan Cells

Dermis

• Vascular

• Contains hair follicles, sweat glands, & oil glands

• Strong, flexible tissue

• Has 2 layers

What are the 2 layers of the dermis?

• Papillary layer

• Reticular layer

What cells are located in the dermis?

• fibroblasts

• Mast cells

• Macrophages

• Leukocytes (white blood cells)

Which layer of the dermis is highly vascularized? (Hint: Most superficial)

Papillary layer

Describe the papillary layer

• Highly vascularized

• Contains Epidermal ridges (fingerprints)

• Contain touch & pain receptors

What layer of the dermis contains collagen & elastic fibers and also consists of dense irregular connective tissue

Reticular layer

Cutaneous Sensations

Skin that’s supplied with cutaneous sensory receptors

What are the sensory receptors of the dermis?

• Merkel disc

• Meissner’s corpuscle

• Pacinian’s corpuscle

• Root hair plexus

• Free nerve endings

Merkel disc

Detects light sensations

Meissner’s corpuscle

Detects light touch/sensations

Pacinian’s corpuscle

Detects Deep touch/pressure

• Think about Pacinian being located deeper into the dermis

Free nerve endings

Detect painful stimuli

Root hair plexus

Wind blowing through hair

What layer makes up about 80% of the dermis?

The reticular layer

What is collagen’s role in the dermis?

Collagen binds water, helping to hydrate the skin

How does elastic fibers contribute to the reticular layer of the skin?

It gives the skin elasticity

How does the reticular layer of the dermis get its strength

Dense irregular connective tissue gives the reticular layer its strength

Which layer of the dermis contains LARGER blood vessels, lymph vessels, and nerve fibers

The reticular layer

What is a blister?

The accumulation of fluid that creates a pocket that separates the dermis and the epidermis

What fibers make up the lines of cleavage?

Elastic & collagen fibers

What are the lines of cleavage?

Collagen & elastin fibers arranged in parallel uniform on the skin

What does the lines of cleavage do in regards to the skin?

Resists force in a specific direction

What is the significance in regards to line of cleavage?

Lines of cleavage helps a surgeon know where to make appropriate cuts. This will help in regards to proper healing of the skin & less scarring, as well as making sure the cut stays shut.

Is the hypodermis considered a layer of the skin?

Technically no, because it’s mainly composed of fats.

What are the other names for the hypodermis?

Subcutaneous layer, superficial fascia

What are the main functions of the hypodermis?

• Heat regulation/insulation

• Energy reservoir

What cells make up the hypodermis?

Adipocytes (fat cells)

Why are injections mostly injected subcutaneously?

Because its mostly composed of fats; no major organs & only some capillaries.

What is the fat distribution in females?

Back the cervical (neck), arms, thighs, stomach, breasts, and gluteal region.

What is the fat distribution in males?

Abs/abdomen, gluteal region, thighs

What are the major types of pigments of the skin?

• Eumelanin

• Carotene

• Hemoglobin

• Jaundice

Eumelanin

Brown pigmentation

Carotene

Yellow to orange pigmentation found in certain plant products

Where does carotene accumulate at in the skin?

Carotene accumulates in the Str. Corneum & Hypodermis

What can carotene be converted into?

Vitamin A

Hemoglobin

Red pigmentation from RBCs

Why do caucasian people typically show more hemoglobin pigmentation?

Because they have less pigmentation, the skin is transparent enough for hemoglobin to be seen through.

Cyanosis

Blue pigmentation due to the lack of oxygen/little to no presence of oxygen in hemoglobin

Jaundice

Yellow pigmentation of the skin, typically indicating liver problem

What does jaundice indicate?

Indicates a buildup of builirubin (waste product)

Vitiligo

Loss of melanocytes & color in the skin

Albanism

Have melanocytes, but the melanin is not produced or melanin can’t be distributed to keratinocytes

What areas of the body are not covered with

• soles of feet

• palms of hands

• lips

• portions of external genitalia

What are the 3 functions of hair?

• protects and insulates

• Guards openings of the body (nose, eyes, etc.)

• sensitive to light touch

What are the structures of the hair follicles?

• hair bulb

• hair shaft

• hair root

• arrector pilli muscle

• sebaceous gland

Steps of hair growth cycle

• follicle becomes active

• produces new hair

• club hair is shed

What are the accessory organs of the hair?

• arrector pilli muscle

• sebacous gland

• sweat glands

Arrector pilli muscle

contracts to make the hair stand; produces goosebumps

Is the arrector pilli muscle voluntary or involuntary?

involuntary

sebaceous gland

lubricates the hair

What are the different types of hair?

• Terminal hair

• Vellus hair (peach fuzz)

• lanugo

Lanugo

Fine hair that appears on a fetus in the last 3 months of development

Vellus (peach fuzz)

Bdoy hair of female and children; very pale and fine

Terminal hair

Corser, longer (darker) hair; eyelashes, eyebrows, scalp, axillary (armpit), pubic region

What does terminal hair grow in response to?

Androgens (testosterone)

Sudoriferous (sweat) gland

Sweat gland

Sweat glands are located all over the body, except?

Nipples & part of external genitalia

What are the 2 types of sudoriferous (sweat) glands?

Eccrine & Apocrine

Where is eccrine gland located?

Underneath the sweat pore of the skin

What is the type of mode of secretion eccrine gland uses?

Merocrine; excreted by exocytosis

function of eccrine gland

excretes water and electrolytes through a sweat pore on the skin

Where is eccrine glands found?

All over the body

Where are the most abundant spots where eccrine glands is located?

Palms, soles of feet, & forehead

What are the main components of sweat? How much of it is water?

99% of sweat is water; some saltls, vitamin c, antibodies, metabolic wastes, lactic acid

Where are Apocrine glands most common at?

Axillary (armpit) & anogenital regions

function of apocrine glands

Ducts empty into hair follicles

How is body odor created?

When it’s decomposed by bacteria on the skin

What is Apocrine glands mode of secretion?

Merocrine

perspiration

When water penetrates the surface

What are the 2 types of perspiration?

• insensible

• sensible