integumentary system

integumentary system

the body's largest organ system, encompassing the skin and its various appendages.

hair, nails, glands, blood vessels, muscles, nerves

Appendages/Components of integumentary system

epidermis

The skin has 2 major layers: The outer is called the

dermis

The skin has 2 major layers: The inner is called the

subcutaneous layer

is located underneath the dermis.

hypodermis

other name of subcutaneous layer

Protection, Sensation, Temperature regulation, excretion, Vitamin D synthesis

Functions of the Integumentary System

Skin

also known as the integument.

epidermis and dermis

composed of two distinct regions

epidermis

composed of epithelial cells, is the outermost protective shield of the body.

dermis,

making up the bulk of the skin, is a tough, leathery layer composed mostly of fibrous connective tissue.

Epidermis

making up the bulk of the skin, is a tough, leathery layer composed mostly of fibrous connective tissue.

Keratinocytes, melanocytes, Merkel cells, Langerhans cells

epidermis Contains 4 distinct cell types which are

epidermis

Avascular and receives nutrients from dermis

epidermis

Made up of 5 (4) distinct layers;

Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum, Stratum corneum

epidermis is made up of 5 distinct layer which are?

Keratinocytes

\[EPIDERMAL CELLS\] produce keratin

Melanocytes

\[EPIDERMAL CELLS\] produce the pigment melanin

Langerhans cells/ Intraepidermal macrophages

\[EPIDERMAL CELLS\] are involved in the immune responses.

Merkel cells/ Tactile epithelial cells

\[EPIDERMAL CELLS\] function in the sensation of touch.

Keratin

\- a tough fibrous protein that provides protection

keratinocytes, melanocytes, Langerhans cells/ Intraepidermal macrophages, Merkel cells/ Tactile epithelial cells

4 epidermal cells

Stratum basale

deepest layer of epidermis firmly attached to the dermis.

Stratum basale

Also known as Stratum germinativum.

Stratum basale

Consists of a single layer of stem cells representing young keratinocytes and exhibits a lot of mitotic activity.

Stratum basale

Layer also contains Merkel cells and spider shaped melanocytes (10- 25%).

Stratum spinosum

aka (spiny layer)

Stratum spinosum

Several layers thick; Thickest layer in thin skin.

Stratum spinosum

Derives name from many spiny keratinocytes scattered through this layer.

Stratum spinosum

Spiny appearance is due to fixation artifact and attached desmosomes.

Stratum spinosum

Langerhans cells present act as part of immune system to scavenge foreign proteins that invade epidermis.

Stratum granulosum

Consists of 1-5 layers of keratinocytes

Stratum granulosum

Also contains keratinohyaline granules and lamellated granules.

Stratum granulosum

Former cells form keratin in more superficial layers of epidermis and latter cells form a glycolipid layer which acts as waterproofing.

Stratum granulosum

Receives nutrient from capillaries in dermal layer.

Stratum granulosum

Layers above here are dead keratinized cells

Stratum lucidum

aka clear layer

Stratum lucidum

Occurs only in thick skin of palms and soles

Stratum lucidum

Does not occur in thin skin

Stratum lucidum

Consists of a few layers of flat dead keratinocytes that have a transparent appearance.

Stratum corneum

also known as horny layer

Stratum corneum

Most superficial layer of epidermis, Many cell layers thick

Consists of dead keratinized cells that are filled with keratin and no longer have nuclei and organelles.

Stratum corneum

It is the layer that is shed as dandruff flakes from scalp

Stratum corneum

Average person sheds \~ 40 lbs. in a lifetime

Dermis

Fibrous connective tissue and Second layer of skin

Dermis

It is a strong flexible dense irregular connective tissue containing mast cells, macrophages, fibroblasts, and scattered leukocytes.

Dermis

Also contains elastic, reticular and collagen fibers.

Dermis

what binds the body together.

Dermis

Richly supplied by nerves and blood vessels.

Dermis

Consists of 2 layers: Papillary and Reticular

Papillary layer

Most superficial layer of dermis consists of areolar CT with collagen and elastic fibers.

Papillary layer

Dermal papillae form dermal ridges that form our fingerprints, palm prints and footprints.

Corpuscles of touch or Meissner corpuscles

\-nerve endings that are sensitive to touch

Free nerve endings

initiate signals that give rise to sensations of warmth, coolness, pain, tickling, and itching

Reticular layer

80 % of dermis

Reticular layer

Named for its network (reticulum) of collagen fibers

Reticular layer

Consist of dense irregular CT

Reticular layer

Combination of collagen and elastic fibers - strength

Reticular layer

Extensibility and elasticity

Extensibility

\-the ability to stretch

Elasticity

\-the ability to return to original shape after stretching

Free nerve endings

sensitive to temperature, pain (nociceptors) and pressure

Meissner’s corpuscles

sensitive to light pressure, discriminative touch, low vibrations.

Pacinian/lamellated corpuscles

sensitive to deep pressure, high frequency vibration. Extends to subcutaneous layer.

Hypodermis

also known as the fatty layer

fatty layer

other name of hypodermis

Hypodermis

Not actually a layer of the skin

Hypodermis

Also known as a subcutaneous layer or superficial fascia.

Hypodermis

Deep to dermis consists of adipose and areolar connective tissue.

Hypodermis

Anchors skin to deeper structures (mostly muscle) but loose enough to allow skin to be flexible and movable.

Hypodermis

Acts as a good body insulator

Melanin

produced by melanocytes but accumulates in keratinocytes of stratum basale and stratum spinosum.

Melanocytes

synthesize melanin in the melanosome from the amino acid tyrosine in the presence of an enzyme called tyrosinase.

Eumelanin

brown to black

Pheomelanin

yellow to red

tyrosinase

Melanocytes synthesize melanin in the melanosome from the amino acid tyrosine in the presence of an enzyme called?

Carotene

yellow pigment most conspicuous in heel calluses and corns in stratum corneum.

Carotene

stored in the stratum corneum and fatty areas of the dermis and subcutaneous layer in response to excessive dietary intake

Hemoglobin

red pigment in RBCs imparts red color to skin through blood vessels

Melanin, Carotene, Hemoglobin

Three pigments contribute to skin color

merocrine gland, sebaceous gland, apocrine gland

3 skin glands

Sebaceous glands

produce an oily secretion called sebum.

Sebaceous glands

Usually opens into a hair follicle.

Sebum

is a mixture of triglycerides, cholesterol, proteins, and inorganic salts.

Sebum

coats the surface of hairs and helps keep them from drying and becoming brittle.

Sebum

also prevents excessive evaporation of water from the skin.

Sebum

It keeps the skin soft and pliable, and inhibits the growth of some (but not all) bacteria.

apocrine and merocrine

Sudoriferous “sweat” glands are two kinds

Merocrine/Eccrine

most numerous; produce watery perspiration for cooling body; most abundant on palms, soles and forehead, thermoregulation, emotional sweating

Apocrine

present in groin, axilla, anal, areola, and beard regions; ducts open into hair follicle; sweat is thicker milkier due to fatty acids. Strong odor is due to bacterial decay.

Ceruminous glands

found only in the external auditory canal.

cerumen

Ceruminous glands Secretion is called _______ which is waxy and has a viscous texture and bitter taste. It repels insects and kills bacteria and waterproofs the eardrum.

Mammary glands

specialized sweat glands that produce milk in pregnant females.

Hair

is made of dead keratinized cells and consists of a bulb, root and shaft and grows within a follicle.

Arrector pili muscle

under sympathetic control

medulla, cortex, cuticle

Three concentric layers of hair

medulla

concentric layers: central core

cortex

concentric layers: several layers of flattened cells;

cuticle

concentric layers: single layer of cells that overlap like shingle forming outermost portion gives hair strength and keeps it from matting