BIOL 1410 Integumentary System

LECTURE 9

What does the “epi” prefix mean?

“Surface”

Is the hypodermis considered part of the skin?

No, it is BELOW. (Hypo = below)

What does “basale” mean?

“Bottom,” think B for Basale/Bottom

The integumentary system consists of…

skin, hair/nails/glands, muscles, sense receptors, hypodermis

What are the 2 layers of the skin called?

Epidermis (upper), dermis (lower)

What layer is below the skin (dermis)?

Hypodermis

What is are the cells classified as in epidermis?

Stratified squamous

Is the epidermis vascular or avascular?

Avascular

What are the 4-5 strata of epidermis (based on cell types)?

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.

Which of the 5 strata are only visible in thick skin?

Stratum lucidum

Where on the body is considered “thick skin”?

Palms of hands and soles of feet

What are the two cell types of stratum basale?

Keratinocytes and melanocytes

What cells produce melanin?

Melanocytes

What about melanocytes makes people have different skin colours?

We all have relatively the same amount of melanocytes, but our cells produce different amounts/shades of melanin

What makes areas of thin skin appear pink?

Hemoglobin (in blood)

What process do keratinocytes actively undergo?

Mitosis

What material do keratinocytes produce?

Keratin (tough protein)

What are the 2 terms for people who have no melanin?

Albinism or achromia

Does stratum spinosum have high, low, or no levels of mitosis?

Low levels

Does stratum granulosum have high, low, or no levels of mitosis?

No mitosis

Stratum granulosum contains granules. What 2 things do granules produce?

Keratin (strength) and waterproofing glycolipids (prevent water loss)

Stratum granulosm contain the last layer of ______ cells.

“living”

Does stratum lucidum have high, low, or no levels of mitosis?

No mitosis

Stratum lucidum and stratum corneum have flat, ____ cells.

“dead”

How many layers of flat, dead cells are in stratum corneum?

20-30 layers

What are the cells in stratum corneum filled with? What are they surrounded by?

Filled with keratin (tough protein) and surrounding by waterproofing glycolipids (prevents water loss)

Which layer is shed and replaced from below?

Stratum corneum

What 5 things are contained in the dermis?

Blood vessels, nerves, glands, hair follicles, arrector pili muscles

What are the two sub-layers of the dermis?

Papillary layer, reticular layer

What is the cell classification of the papillary layer?

Areolar CT

Is the papillary layer vascular or avascular?

Vascular

The papillary layer includes dermal papillae. What are they/what do they form?

Dermal papillae are projections from the dermis into the epidermis, they form epidermal ridges (fingerprints!)

Which layer of the dermis forms the majority of it (Papillary or reticular)?

Reticular layer forms majority of dermis

What is the cell classification of the reticular layer?

Dense irregular CT

Does thickness refer to epidermis or dermis?

Epidermis

Does thin or thick skin cover most of the body?

Thin

Lucidum is present in _____ skin

“thick”

_____ skin has hair follicles, sebaceous glands, and arrector pili muscles

“Thin”

What are the (3) epidermal derivatives?

Hair, nails, skin exocrine glands

All the cells in hair are ____

“dead”

What are the 3 parts of hair?

Root, shaft, follicle

What is the hair root?

Part of hair embedded within the skin

What is the hair shaft?

Visible part of hair above the skin surface

What does the hair follicle surround?

Surrounds root

What are the 3 parts of the hair follicle (which is a part of the hair)?

Epithelial root sheath, bulb, matrix

What is the epithelial root sheath?

Several epidermal layers extended into the dermis

What is the bulb in the hair follicle?

Expanded region at the base of the root

What is the matrix in the hair follicle?

Single layer of cells

What are the cells in the matrix of the hair follicle derived from?

Basale cells

Which part of the hair follicle is the site of hair growth and melanin for hair colour?

Matrix

What (5) things are associated with each hair follicle?

Outer CT sheath, hair papilla, root hair plexus, sebaceous (oil) gland, arrector pili muscle

What is the purpose of the free nerve ending in the root hair plexus?

Touch

What is the purpose of the outer CT sheath?

To hold the follicle in place

What is the outer CT sheath and hair papilla formed from?

Formed from the dermis

Hair papilla extends upward beneath the _______

“matrix”

Which association with each hair follicle contains the blood supply for growing hair?

Hair papilla

The sebaceous (oil) gland opens into the _______

“follicle”

What muscle subtype is the arrector pili muscle made of?

Smooth muscle

Which association with each hair follicle causes “goosebumps”?

Arrector pili muscle

Nails are very heavily _________ epidermal cells

“keratinized”

Nails consist of what 3 components?

Nail root, body, and free edge

What are the 4 types of skin exocrine glands?

Sebaceous glands, sudoriferous glands, ceruminous glands, mammary glands

What are sebaceous glands mainly connected to?

Hair follicles

What do sebaceous glands secrete? What is it?

Sebum - oily mix of fats, salts and proteins

What are the 4 purposes of sebum?

Softens, lubricates hair and skin, prevents dry-out, antibiotic

What do sudoriferous glands secrete?

Sweat (sweat glands)

Do sudoriferous glands have secretory portions in dermis of thick or thin skin?

Trick question; both!

Do sudoriferous glands have ducts?

Yes, they open onto skin surface

What are the 3 functions of sudoriferous glands?

Temperature regulation, antibiotic actions (acidic), removes wastes (e.g. urea)

What kind of glands are ceruminous glands?

Modified sweat glands

Where in the body are ceruminous glands found?

In the ear canal

What do ceruminous glands produce?

Ear wax

What kind of glands are mammary glands?

Also modified sweat glands

What do mammary glands produce?

Milk

What is a receptor?

Sensory neuron

What do receptors/sensory neurons respond to?

Responds to stimuli (e.g. touch, temp., pain)

What are the 4 major types of cutaneous sense receptors?

Touch receptors, pressure receptors, thermoreceptors, nociceptors

Which type of receptor has free nerve endings in epidermis?

Touch receptors

Which type of receptor has free nerve endings in dermis?

Pressure receptors

Apart from free nerve endings, what are the 2 other types of touch receptors?

Root hair plexuses and tactile (Meissner’s) corpuscles

Where are tactile (Meissner’s) corpuscles found?

Found in dermal papillae

Define corpuscle

CT capsule surrounding nerve ending

Apart from free nerve endings, what is the other type of pressure receptors?

Lamellar (Pacinian) corpuscles

Where are lamellar (Pacinian) corpuscles found?

Deep in dermis or hypodermis

Thermoreceptors are free nerve endings for what stimuli?

Temperature

Nociceptors are free nerve endings for what stimuli?

Pain

Why do you feel no pain with a 3rd degree burn?

Because nociceptors have been destroyed

What is the hypodermis also called?

Subcutaneous layer/superficial fascia

What are fascia?

CT layers that surround and support organs

What is the cell classification of the hypodermis?

adipose CT

How much of the body’s adipose tissue is stored in the hypodermis?

½ or 50%

What is the purpose of the hypodermis?

Insulation

What is psoriasis?

Autoimmune disorder, causes accelerated mitosis of keratinocytes in the stratum basale

What does the accelerated cell cycle in psoriasis delay?

It delays maturation and differentiation of keratinocytes

Due to psoriasis, keratinocytes accumulate in the epidermis, causing the stratum _______ to fail to shed. What is the blank term, and what does this result in?

“Corneum,” results in a thick scaly area on the surface of the skin (plaque)

Why do we have fingerprints?

To improve our grip

Review: is epidermis vascular or avascular?

Avascular

What does plexus mean?

Network