Integumentary System

pages 61-72

What does the integumentary system consist of?

• skin

• accessory structures

  • hair

  • sebaceous glands

  • sweat glands

  • ceruminous glands

  • mammary glands

  • nails

List the functions of the integumentary system (5)

• protection

• body temperature regulation

• sensation

• excretion

• vitamin D production 

Describe the function of the integumentary system: protection

• protects against

  • ultraviolet light

  • bacterial invasion

  • dehydration 

Describe the function of the integumentary system: body temperature regulation

• regulates body temperature by way of blood flow and sweating

Describe the function of the integumentary system: sensation

• nerve endings and receptors that detect

  • temperature

  • touch

  • pressure

  • pain 

Describe the function of the integumentary system: excretion

• removal of waste through secretion

Describe the function of the integumentary system: vitamin D production

• produces vitamin D with the help of UV light

Describe the skin

• protective barrier

• 7% of total body weight 

• divided into two regions

  • epidermis

  • dermis 

Describe the hypodermis

• located just below the dermis

• made up of subcutaneous tissue and superficial fascia 

Describe the epidermis

• composed of stratified squamous keratinized epithelial tissue 

• avascular

• contains cells

  • keratinocytes

  • melanocytes

• 4-5 layers (depends on type of skin)

Describe keratinocytes

• found in epidermis

  • majority of cells

• epithelial cells that produce keratin 

Describe melanocytes

• found in stratum basale of epidermis

• produce melanin

  • melanin sits on top of nuclei of cells and protects them from UV radiation 

• all races have the same number of melanocytes

Describe how we have different skin colors

• all races have the same number of melanocytes

• differences in skin color may be due to difference in melanocyte activity or the speed of melanin breakdown in keratinocytes

  • darker skin may have more melanocyte activity

  • paler skin breaks down melanin faster in keratinocytes 

What characteristics determine the type of skin?

• number of layers in the epidermis

  • thickness of these layers

• if hair is present 

What are the two types of skin?

• thick skin

• thin skin

Describe thick skin

• 5 layers form the epidermis

• DO NOT contain hair follicles or oil glands 

• found in

  • palms of hands

  • soles of feet

  • finger tips

Describe thin skin

• 4 layers form the epidermis 

• found everywhere thick skin isn’t

What are the 5 layers of the epidermis of thick skin?

• stratum basale

• stratum spinosum

• stratum granulosum

• stratum lucidum

• stratum corneum 

What are the 4 layers of the epidermis of thin skin?

• stratum basale

• stratum spinosum

• stratum granulosum

• stratum corneum 

Describe stratum basale

• found in thick and thin skin

• one layer thick

• mitosis occurs here 

  • newer cells at bottom

  • older cells at top

Describe stratum spinosum

• found in thick and thin skin

• several layers thick

• lots of desmosomes present

Describe stratum granulosum

• found in thick and thin skin

• 2-5 cell layers thick

• contains granules for strength and waterproofing

  • keratohyalin granules give the epidermis its strength 

  • lipid filled lamellated bodies give the epidermis is waterproof property

Describe stratum lucidum

• found in thick skin only

• “clear layer”

Describe stratum corneum

• found in thick and thin skin

• 20-30 cells thick

• provides protection from external environment

• dead cells

• thicker in thick skin

What gives the epidermis its strength?

• keratohyalin granules

What gives the epidermis its waterproof property?

• lipid filled lamellated bodies

Describe the dermis

• deep to the epidermis

• connective tissue of skin

  • thicker than epidermis

• richly supplied with

  • nerves

  • blood vessels

  • lymphatics

  • oil & sweat glands

• divided into two regions

  • papillary 

  • reticular 

Describe the papillary layer of the dermis

• superficial layer of the dermis (on top)

• composed of areolar connective tissue

• has projections called dermal papillae 

  • indent the dermis (makes it harder to separate the layers)

    • separation of the papillary layer of the dermis from the epidermis can result in a blister

Describe the reticular layer of the dermis

• deep to the papillary layer (deepest layer of dermis)

• composed of dense irregular connective tissue

Describe hair

• found on all surfaces except

  • palms of hands

  • soles of feet

  • fingertips

  • lips 

• made up of the 

  • hair follicle

  • root

  • shaft

Describe the hair follicle of hair

• contains the matrix

  • germinal layer where hair growth is initiated

    • pushes other cells distally

    • cells keratinize as they move up

• contains melanocytes

  • brown and black eumelanin (brown and black hair)

  • small amount of brown eumelanin (blonde hair)

  • pheomelanin (red hair)

Describe the root of hair

• portion of hair within the hair follicle

Describe the shaft of hair

• portion of hair that extends from the hair follicle

• functions

  • protection 

    • eyebrows prevent sweat from entering eyes

    • eyelashes prevent debris from entering eyes

    • nose and ear hair prevent debris from entering the body

  • sense orgain

Describe nails

• protects ends of fingers and toes

• fingernails grow at a rate of about 1-4 inches per year

  • grow twice as fast as toenails

• made up of the

  • matrix

  • lunula

  • quick/nail bed

  • nail root

  • nail body / nail plate

  • hyponychium

Describe the matrix of the nail

• germinal layer where nail growth is initiated

  • push other cells distally

  • cells keratinize as they move up

Describe the lunula of the nail

• white, crescent-shaped, visible region of the nail matrix

• white in color because it is thick and blood vessels do not show

Describe the quick / nail bed of the nail

• layer of epithelial cells where the nail attaches to the fingers and toes

• well vascularized

  • therefore, appears pink

• adds to the growth of the nail

  • thickens the nail

Describe the nail root of the nail

• area of the nail that is hidden by the eponychium / cuticle

• cuticle fuses nail root to the skin and provides a waterproof barrier 

Describe the nail body / nail plate

• visible area of the nail

Describe the hyponychium of the nail

• area of skin at the tip of the fingers

• fuses nail plate to the skin

• provides a waterproof barrier

Describe glands

• sebaceous glands 

• eccrine / merocrine sweat gland

• apocrine sweat gland 

Describe sebaceous glands

• generally attached to hair follicle by ducts

• most numerous on face and scalp

• secrete oily substance called sebum

• sebaceous glands “appear” at puberty

  • due to an increase in hormones

Describe sebum

• oils the hair and lubricates the skin

• helps prevent water loss

• inhibits growth of certain bacteria

Describe eccrine / merocrine sweat gland

• contain a duct that extends through the epidermis to the skin surface

• secrete sweat

  • everywhere on the body

  • excreted onto the skin via a duct

  • aids in regulating body temperature

  • excretes nitrogenous waste  

Describe the apocrine sweat gland

• contains a duct that extends into the hair follicle

• secrete thick, sticky sweat into hair follicles

  • sweat makes its way onto the skin

  • decomposed by skin bacteria and becomes odorous

    • this scent is used as a form of communication in other animals

    • bacteria is killed by deodorants

    • antiperspirants inhibit sweat production

• found in

  • armpits

  • around areola

  • anus

  • genitals

• these glands “appear” at puberty

  • due to an increase in certain hormones

What are the three types of skin cancer?

• basal cell carcinoma

• squamous cell carcinoma

• malignant melanoma

Describe basal cell carcinoma

• least malignant and most common

• cells of the stratum basale proliferate and invade the dermis and hypodermis

• appears as shiny dome shaped nodules 

  • can be surgically removed 

  • 99% cure

Describe squamous cell carcinoma

• arises in keratinocytes of the stratum spinosum

• appears as small, scaly, red elevation

• metastasizes (spreads to other sites in the body)

Describe malignant melanoma

• cancer of the melanocytes

• VERY dangerous, spreads faster

• rarer of the skin cancers, but it is on the rise

• survival rate depends on how early you catch it and metastasis

What is the function of the Meissner’s corpuscle?

• detects light/soft touch

What type of cell junction can you find in the stratum spinosum?

• desmosomes

  • cell to cell attachment

What is the function of the Pacinian corpuscle

• detects deep touch

What is this a picture of? Identify the highlighted structures and describe them.

Thick skin

• from palm

A: Epidermis

• composed of stratified squamous keratinized epithelial tissue

B: Dermis

• composed of areolar connective tissue (papillary layer) and dense irregular connective tissue (reticular layer)

C: Hypodermis

• composed (mainly) of adipose tissue

• NOT PART OF SKIN

What is the difference between thick and thin skin?

• thick skin has 5 layers, thin skin has 4 layers

• thick skin does not contain hair follicles or oil glands, thin skin does

What is this a picture of? Identify the highlighted structures and describe them.

Thick skin

A: Stratum Corneum

• top layer of epidermis

B: Stratum Lucidum

• 2nd layer of epidermis

• only in thick skin

C: Stratum Granulosum

• 3rd layer of epidermis

D: Stratum Spinosum

• 4th layer of epidermis

E: Stratum Basale

• bottom layer of epidermis

F: Dermis

What is this a picture of? Identify the highlighted structures and describe them.

Think Skin

A: Epidermis

• composed of stratified squamous keratinized epithelial tissue

B: Dermis

• composed of two layers

C: Papillary layer

• top layer of the dermis

• composed of areolar tissue

D: Reticular layer

• bottom layer of the dermis

• composed of dense irregular connective tissue 

What is this a picture of? Identify the highlighted structures and describe them.

Thin skin

A: dermal papillae

• protrusion of the papillary layer of dermis into the stratum basale of the epidermis

B: rete peg

• protrusion of the stratum basale layer of the epidermis into the papillary layer of the dermis

C: melanocyte

• cell that produces melanin

• located in the stratum basale of the epidermis

What is this a picture of? Identify the highlighted structures and describe them.

Thin skin

• from scalp

A: hair follicle

B: root of hair follicle 

What is this a picture of? Identify the highlighted structures and describe them.

Thin skin

• from scalp

A: hair follicle

B: sebaceous glands

• secrete sebum (oily substance)

What is this a picture of? Identify the highlighted structures and describe them.

Think skin

• from scalp

A: hair follicle

B: sebaceous gland

• secretes sebum

C: arrector pili muscle

What is the function of arrector pili muscles, and what type of muscle tissue do they contain?

• create goose bumps (make hair stand up)

• contain smooth muscle tissue 

What is this a picture of? Identify the highlighted structures and describe them.

Skin

A: Meissner’s corpuscle 

• detects light/soft touch

• located in the dermal papillae 

B: stratum basale

C: stratum spinosum

What is this a picture of? Identify the highlighted structures and describe them.

Hypodermis

A: Pacinian corpuscle

• detects deep touch

• located in the hypodermis

  • surrounded by fat cells