Anatomy Integumentary System Guide

4 functions of the skin

1. Protects body from infection

2. Protects from extreme temperatures

3. maintains balance of fluids

4. Synthesize vitamin D

The integumentary system includes:

Hair

Sweat glands

Oils glands

Nails

skin

3 main layers of the skin

Epidermis (outer layer)

Dermis (middle layer)

Hypodermis (deep layer)

The Epidermis is made of…

Stratified squamous epithelial tissue

4 Epidermal cells

1. Keratinocytes

2. Melanocyte

3. Dendritic or Langerhans

4. Tactile or merkel

Keratinocytes

Form a tough, waterproof, protective barrier

→Millions die every day, new epidermis every 4-6 weeks.

Melanocyte

spider shaped cell that synthesizes the pigment that protects us from UV rays

→no matter skin color each person has the same number of melanocyte cells. The breadth of their spidery cellular extensions determine how much melanin they contain

Dendritic or langerhans

Star-shaped white blood cells that are immune cells that protect against infection

→ Once migrated to the epidermis, their long skinny tendrils run around the keratinocytes and spend much of their time ingesting the unwanted invaders on your skin.

Tactile or merkel

Form sensory receptors for tough

3 layers of epidermis

1. Stratum Corneum

2. Stratum Lucidum

3. Stratum Granulosum

4. Stratum Spinosum

5. Stratum Basale

Stratum Corneum

“horny layer’ made of 20-30 layers of dead keratinocytes, the roughest layer protecting you from basic environmental threats

Stratum Lucidum

“clear layer” 2-3 rows of clear flat dead keratinocyte cells only found in thick skin of palms and soles

→ in thin areas of skin this is the missing layer

Stratum Granulosum

“granular layer” contains living keratinocyte cells that are getting compressed and flattened as they move up the epidermis layer

Stratum Spinosum

“spiny layer” getting closer to point of cell regeneration and mitosis, cells look prickly when dehydrated and contain filaments that help them hold together

Stratum Basale

“basal layer” single layer of columnar cells, aka cell factory: most new-cell production happens, connects to epidermis to dermis

order of epidermis layers

Come, Lets Get SunBurned

Function of epidermis

The only layer you can actually see and is waterproof. The layer protects against infection, dehydration, and UV radiation, while continuously producing new skin cells, regulating hydration, and determining skin color.

Protein that gives strength in dermis

collagen

Protein that gives elasticity

elastin

dermis contains

capillaries

Blood vessels

Nerve fibers: register sensations

Hair follicles

Oil glands

Sweat glands

2 layers of the dermis

Upper Papillary

Reticular layer

Upper Papillary

composed of areolar connective tissue riddled with dermal papillae (peg-like projections that help with grip)

Reticular layer

 makes up 80 percent of your dermis, made of dense connective tissue. All dynamic parts contained in the dermis are distributed between both its layers. 

→ This layer bleeds and feels pain

Hypodermis aka

 subcutis

hypodermis contains…

 mostly adipose connective tissue

Function of hypodermis

Provides insulation, energy storage, shock absorption, and helps anchor the skin. Additionally, this is where body fat hangs out 

primary function of the skin

protective barrier against environmental hazards, pathogens, and UV radiation

Types of cutaneous sensory receptors

Tactile corpuscles

Lamellar corpuscles

Hair follicle

Tactile corpuscles

constantly aware of feelings on the body

Lamellar corpuscles

registers the sense of pressure

Hair follicles

can pick up slight feelings, such as a breeze

Similar to urination, sweat….

expells small amounts of urinary waste

Skin retains 5%…

of our entire blood volume

Body temperature regulation is done by..

Blood and sweat glands work together

To regulate heat loss in cold temperatures

blood vessels constrict (causing blood to head deeper into your tissues and help keep vital organs warm.)

In warmer temperatures

blood vessels slowly relax (allowing blood to come back up to the surface.)

Blue skin

(cyanosis): in white people it can idicate heart failure, poor circulation, or severe respitory issues, blood is depleted of oxygen.

yellow skin

 (jaundice): signifies liver disorder, yellow bile starts accumulating in the blood stream

red skin

(erythema): indicates fever, inflammation, or allergy, all of which expand more blood flow to the surface

Melanin protects us…

from Ultraviolet Rays

Your skin needs sunlight…

to produce vitamin D , which is activated in the liver and kidneys

Activated Vitamin D

calcitrol, is circulated to all bones in the body and produce new bone cells

Hairs

skin appendages flexible strands of dead keratin protein

Hair structure

flexible strands of dead keratin protein

Outermost layer of hair

Cuticle

2 Main Regions of hair

Shaft

Root

shaft

where keratinization is complete

root

inside the follicle, where keratinization is still happening

parts of the nail

Nail bed

Nail Matrix

Nail plate

nail bed

 the sensitive, underlying skin that supports the plate

Nail Matrix

or root, which produces new cells at the base

Nail Plate

the visible, hard, keratinized body

2 types of sweat glands

Eccrine

Apocrine

eccrine

more abundant (forehead, palms, and soles) coiled simple tubes start in the dermis and extend through a duct and open a pore on the surface of the skin

→Exist all over the body to assist with maintaining body temperature and excreting waste.

apocrine

(only 2000) start being developed during puberty emptying into hair follicles around armpits and groin. They excrete delux sweat with protiens and fats. Can be orderful when bacteria on skin gets ahold. 

Mammary Gland

secrete milk in lactating people

—>modified apocrine glands

Ceruminous Glands

make earwax

—>modified apocrine glands

Sebaceous Glands

found everywhere but the thick skin in palms and soles of feet. Smaller ducts on limbs but bigger on face, neck and upper chest. They secrete sebum (oily substance) into hair follicles then go to the face. 

Sebum

 helps slow water loss by softening and lubricating the skin.