Integumentary System Flashcards
Know all components
Integumentary System
What is it and what does it do?
Refers to the skin and underlying tissues.
Objectives:
* Protect internal tissues from the external environment (toxins, pathogens, UV rays)
* Stop fluids from leaking out
* Sensing the environment
* Help regulate body temp
Epidermis
The most superficial layer that touches air with stratified squamous epithelia.
Cells are born at the bottom near the basement membrane and then migrate out (up) throughout their life to be sluffed off.
HAS NO BLOOD VESSELS
Keratin
A protein in the cytoskeleton of all cells that provides structural support, makes the epidermis tough + water resistant (lots in epidermal cells)
Keratinocytes
The most common cells in the epidermis that are full of keratin.
They’re born by the basement membrane + move up, becoming more filled with keratin.
Dermis
Refers to the 2 layers of connective tissues under the epidermis that makes up most of the skin. Giving skin elasticity,
blood vessels to diffuse nutrients through + neurons.
Types of Dermis
- Papillary Dermis
- Reticular Dermis
Papillary Dermis
Superficial areolar tissue with lots of space between the protein fibers and blood vessels throughout to diffuse nutrients to the epidermis.
Dermal papilla
Bumps in the papillary dermis protruding up.
ex: finger prints
Reticular Dermis
Layer below papillary dermis that composes most of the dermis with dense irregular connective tissue. Their dense bundles of collagen figers going in all directions resist stretching in all directions.
Cleavage lines
Are gaps between dense bundles of collagen fibers in the reticular dermis.
Surgeons make incisions parallel to these lines:
Run along the axis of limbs
In circles around the trunk
Sensory receptors
Are located in dermis and have neurons that detect different things you feel and sends signals back to the CNS.
Sensory corpuscles
Neurons wrapped in connective tissue that sense touch and the deeper ones sense pressure
Hair follicle receptors
Receptors that are wrapped around follicles to detect movement.
Free nerve endings
The uncovered ends of neurons that touch other tissue to sense pain and temperature.
Blood vessels
Funtion as a highway to provide nutrients and O2 to cells in the dermis and epidermis, transport white blood cells, and thermoregulation.
Thermoregulation:
Too hot → move blood closer to skin
Too cold → move blood away from the skin
Hair
Also called a filament, is composed of dead epidermal cells with lots of harder keratin.
Vellus hair
Thin & pale
On bodies of: women + children, bald spots
Terminal hair
Thick, long, + colored
Located on: the head, pubic region, and on the body of adult men.
Anatomy of Hair
Medulla – Cortex – Cuticle – Follicle – Root – Shaft – Connective tissue sheath – Epithelial sheath – Bulb – Hair papilla
Melanocytes – Hair follicle receptor – Arrector Pili
Medulla
The middle of hair that gives it strength.
Cortex
Squamous cells around medulla that make up most of the hair’s diameter.
Cuticle
One layer around the cortex with overlapping cells that prevent hair from tangling.
Follicle
What hair grows out of in the dermis, it can go down to the hypodermis. They’re formed from the epidermis folding down into the dermis.
Root
The part of the filament that’s inside the follicle.
Shaft
The part of the filament that’s outside the follicle.
Connective tissue sheath
Part of the follicle that’s around the filament formed from the dermis.
Epithelial sheath
The inner part of the sheath that forms from epidermis. Part of it grows and goes into the cortex.
Bulb
Bottom of the follicle where the filament grows.
Hair papilla
The dermal papilla in hair bulbs that provides blood to the growing hair.
Melanocytes
Cells that make the melanin that is added to the growing hair, giving it’s color.
Hair follicle receptor
A sensory neuron that wraps around the follicle to detect hair movement.
Arrector Pili
The smooth muscle attached to the follicle. Hair stands up when it contracts = goosebumps
Vestigial goosebumps
No longer functional for humans other than to serve as an emotional response.
In other animals:
Creates the appearance of being larger
Traps air for warmth
Cutaneous Membrane
Is skin
skin = epidermis + dermis
Hypodermis
Layer under the dermis containing subcutaneous fat that’s composed mostly of adipose with a little areolar tissue.
NOT part of the cutaneous membrane
Anatomy of epidermis
- Stratum Corneum - most superficial
- Stratum Lucidum - few layers above granulosum in the feet and hands
- Stratum Granulosum - 1 or a few layers above Spinosum
- Stratum Spinosum - living keratinocytes
- Stratum Basale - contains stem cells
Stratum Corneum
The most superficial layer where cells sluff off the top all the time and is the thickest layer of dermis.
Stratum lucidum
Located a few layers above the stratum granulosum at the bottoms of feet and palms of hands with clear cells.
Stratum Spinosum
Several layers of cells above the Stratum Basale with living keratinocytes that are making keratin and have lots of keratin but aren’t filled yet. They’re attached by desmosomes that resist stretching.
Stratum Basale
The deepest layer of the epidermis that’s 1 cell thick with keratinocyte stem cells. The stem cells never leave this layer to keep producing keratinocytes.
Stratum Granulosum
Contains 1 or a few layers of cells above the Stratum Spinosum that do karitinization and have glycolipids.
Cellular components begin breaking down at this stage
Keratinization
A major change in keratinocytes by increasing the keratin production to stuff the cells turning them squamous.
Glycolipids
Combinations of carbs + lipids that are secreted by keratinocytes in the granulosum layer to fill spaces between the cell - making the skin more water proof.
Dendritic Cells
Important white blood cells that monitor for pathogens + reports back to the rest of the system.
Melanocytes are
specialized cells that produce and spread melanin.
* People with darker skin don’t have more melanocytes, the cells just make more melanin
* Genetics affects amount of melanin - people whos ancestors lived closer to the equator have more melanin
Melanin
Pigment that gives most of the color to skin and functions to absorb UV rays, protect epidermal cells from DNA damage caused by rays.
The pigments can be red, yellow, or brown.
Exposure to sunlight increases its production.
Carotene
A chemical (vitamin A) derived from food that makes skin oranger.
Hemoglobin
The protein that makes blood red giving the skin a pink color.
Nails
Dead epidermal cells with lots of same hard keratin as hair located distally on digits.
Nail Anatomy
- Root: part of nail growing under the skin
- Body: part of the nail you can see (dead epidermal)
- Bed: living epidermal cells under the body
- Matrix: proximal end of nail under the skin, where nail grows
Cutaneous Glands
Exocrine glands on the skin that release substances onto the skin
ex: sweat glands (apocrine + eccrine), mammary glands
Sweat Glands
Glands responsible for releasing sweat onto the skin. It’s located in dermis + hypodermis and is controlled by the nervous system.
Eccrine Sweat Glands
The most common type of sweat gland because it’s found all over the body with its secretory part is coiled in the dermis. These glands mostly contain water, salt + waste.
Apocrine Sweat Glands
Only found in the armpits and around genitals witha deeper secretory part that has lipids and carbs. These molecules lead to body odors after being degraded by bacteria (probably pharamones).
Mammary glands
Modified sweat glands that lactate, are only found on mammals, and develop during pregnancy in response to hormones.
Sebaceous Glands
secrete sebum onto hair follicles
Sebum
Substance that coats the skin to provides lubrication and waterproofing to skin.
