Integumentary System

15%-20%

The skin is the largest single organ of the body, typically accounting for ____ of total body weight

integumentum

The Skin is also known as the Integument which can from the Latin word “____” which means covering

Ectodermal origin

The epidermis is an epithelial layer of what origin?

Protective

it acts as a physical barrier against thermal and mechanical insults such as frictional forces and against potential pathogens

Sensory

allows the skin to constantly monitor the environment

Thermoregulatory

Constant body temperature is maintained due to skin insulating components and mechanisms for accelerating heat loss

Metabolic

The skin synthesize vitamin D3, needed for calcium metabolism and proper bone formation

Pigmentation of Hair

visual indicator of health involved in attraction of health between the sexes in all vertebrae species

Sexual signalling

The effects of sex pheromones produced by the apocrine sweat glands and other skin glands are also important for this attraction

Stratified Keratinized Squamous Epithelium

What is the primary tissue composition of the Epidermis?

Keratinocytes

Primary cells located at the Epidermis

Melanocytes

also known as pigment-producing cells

Langerhans cells

Antigen Presenting cells

Merkel cells

Tactile epithelial cells

Stratum corneum

20-30 layers of dead, flattened, anucleate, keratin-filled keratinocytes called squames

Stratum lucidum

2-3 layers of anucleate, dead cells; seen only in thick skin

keratohyaline granules.

The stratum granulosum has a cytoplasm filled with intensely basophilic masses called

Stratum granulosum

3-5 layers of keratinocytes with distinct keratohyaline granules which are intensely basophilic

Stratum spinosum

Thickest layer of the epidermis

Stratum germinativum

The spinous layer of the epidermis is also known as?

Stratum basale

Single layer of cuboidal to low columnar cells in contact with with basement membrane

Mitosis

What cell cycle happens at the basal layer of the epidermis?

Stratum lucidum

What layer is found in the Thick skin but is absent on the Thin skin?

Melanocytes

A pale staining, rounded cell bodies located at the basal epidermis and protects nuclear DNA from UV damage

Eumelanin

A brown or black pigment found in hair follicles

Pheomelanin

The similar pigment found in Red Hair

Phaios

Pheomelanin came from the Greek word “____” which means Dusky

Black

The Greek word “melas” means ____

Langerhans cells

monocyte derived macrophage

Basement membrane

It connects dermis with epidermis

Microvascular subpapillary plexus

What lies between the papillary and reticular dermal layer?

arteriovenous anastosomes

The thermoregulatory functions of the dermis is done by _____

Subcutaneous layer

also known as Hypodermis or superficial fascia

• Uncapsulated

• Capsulated

Two types of sensory receptors

Capsulated sensory receptors

More complex structures with sensory fibers enclosed by glia and delicate connective tissue capsules

Uncapsulated sensory receptors

Simple nerve endings with no schwann cell or collagenous coverings

• Merkel cells

• Free nerve endings

• Root hair plexus

Types of uncapsulated receptors

Free nerve endings

respond primarily to high and low temperatures, pain and itching.

Merkel cells

tonic receptors for sustained light touch and for sensing an object’s texture.

Root Hair plexus

surrounding the bases of hair follicles in the reticular dermis that detects movements of the hairs

• Meissner corpuscles

• Lamellated (Pacinian) corpuscles

• Krause end bulbs

• Ruffini corpuscles

Types of capsulated receptors

Meissner corpuscles

initiate impulses when light-touch or low-frequency stimuli against skin

Lamellated (Pacinian) corpuscles

for detection of pressure or firm touch

Ruffini corpuscles

collagenous, fusiform capsules anchored firmly to the surrounding connective tissue.

Krause End bulbs

simpler encapsulated, ovoid structures, with extremely thin, collagenous capsules penetrated by a sensory fiber

Hair

are elongated keratinized structures that form within epidermal invaginations

Hair bulb

The growing hair follicle has a terminal dilation called a

Hair shaft

the part of a hair extending beyond the skin surface is the

Arrector pili muscle

a small bundles of smooth muscle cells that contracts and pull the hair shaft to a more erect position

• Internal Root Sheath

• External Root Sheath

The outermost cells of the hair bulb are continuous with the epithelial root sheath. which two layers can be recognized?

Internal root sheath

completely surrounds the initial part of the hair root but degenerates above the level of the attached sebaceous glands.

External root sheath

covers the internal sheath and extends all the way to the epidermis, where it is continuous with the basal and spinous layers.

• Anagen

• Catagen

• Telogen

What are the major phase of a hair growth?

Anagen

A generally long period of mitotic activity and growth

Catagen

A brief period of arrested growth and regression of the hair bulb

Telogen

A final period of inactivity during which the hair may be shed

Medulla

large vacuolated and moderately keratinized cells and center of the root

Cortex

Densely packed, heavily keratinized and surrounds the medulla

Cuticle

Outermost layer of the Hair root

Nails

Hard plates of keratin on the dorsal surface of each distal phalanx

Nail root

Proximal part of the nail

Nail bed

Contains only the basal and spinous epidermal layers

Nail plate

bound to a bed of epidermis, the nail bed, which contains only the basal and spinous epidermal layers.

Hyponychium

The distal end of the plate becomes free of the nail bed at the epidermal fold called the

Nail matrix

area where cells divide, move distally, and become keratinized in a process somewhat similar to hair formation but without keratohyaline granules.

Sebum

a complex mixture of lipids that includes wax esters, squalene, cholesterol, and triglycerides that are hydrolyzed by bacterial enzymes after secretion.

Holocrine secretion

What type of secretion is a sebaceous glands

False: Merocrine

True or False: The apocrine sweat glands show Holocrine, not apocrine secretion

Glycolipids and lipids

which components of the epidermis provides sealant between adjacent cells

Glassy membrane

What separates the hair follicle from the connective tissue of the dermis?

Dense irregular connective tissue

which structure typifies reticular dermis but not papillary dermis?

• Papillary Layer

• Reticular Layer

Two layers of Dermis

• Loose connective tissue

• Adipocytes

Tissue/cell Present in the hypodermis

Stratum corneum

Layer of the skin that protects against friction and water loss