11 - Integumentary System

skin

Largest organ in the body based on bulk

-Largest organ in the body based on bulk

-Protects from desiccation and the environment

-Communicates with environment

What are the major functions of the skin?

epidermis & dermis

What are the 2 major components of the skin, that are mutually dependent?

1. breed

2. age

3. sex (for different species)

Structure and thickness of skin vary based on what 3 main things?

Mechanical stress

Body location

Species adaptions

Why does thickness vary?

Skin layer- corneum

Which layer of the epidermis serves as the barrier to water loss and pathogens?

Skin layer:stratum lucidum

Which layer of the epidermis is the thin hyaline layer? Provides extra protection in specialized regions

Skin layer:stratum granulosum

Which layer of the epidermis is the transitional zone between viable cells below and keratinized cells above? Keratinization transition

Skin layer: spinosum

Which layer of the epidermis is known as the prickle-cell layer, where the cell junctions look like spines? Mechanical strength

skin layer: basale

Which layer of the epidermis has keratinocytes and is in contact with the basement membrane of the dermis below? Stem cell layer

reviewed

Review

Keratinocyte

Epidermal cell type: what is the cell type responsible for barrier formation

melanocytes

Which cell type of the epidermis is associated with the following?

-Melanin pigment in the cytoplasm

-Dendritic processes

• UV protection: Prevents sunburn and DNA damage

mast cells

Which cell type of the epidermis is associated with the following?

-Anticoagulation

-Stimulate local inflammatory reactions to dispose of antigens

langerhans cells

Which cell type of the epidermis is associated with the following?

-Take up antigens and present to T cells

-Why several bovine species have immune modulated resistance to ticks

-Particularly important in ruminants

-Produce lymphokines (IL-1)

merkel cells

Which cell type of the epidermis is associated with the following?

-Found in epidermis with hairy surface, nail matrix, palms, subepidermal mesenchyme

-Sensory receptors

• Touch sensation

basal

The basal lamina of the basement membrane is secreted by _____ cells of the epidermis

Basement membrane

What is the layer of skin that is the barrier against pathogens that also regulates the passage of nutrients and waste? Is the interface between the dermis and the epidermis

dermis

The _____ is fibrous connective tissue of skin

Support and protect epidermis→ strength and flexibility

Regulate body temp by utilizing blood vessels and sweat glands

Facilitate sensation by using nerve endings

what are the dermis characteristics

nourishment

Epidermis grows on the dermis and obtains _____ from it

Apart of the dermis

Maintain skin health and structure. Can control electrolytes and water leading to skin hydration

Mucopolysaccharides are associated with the [dermis/epidermis] and do what

hypodermis

-Loose fibrous connective tissue plus adipose tissue

-Connects skin to muscles and bone

-Insulation and fat storage

-protection, fat gives cushion

Thermoregulation

Protection- physical barrier from sun

sensory perception- tactile hair

communication

The body hair of animals serves what purposes?

true

The body hair of animals is fibrous and bulky. True or false?

tactile hair

-Thick hair above lips, close to nose

are very sensitive

-Hair follicle → outer and inner dermal sheaths connected by trabeculae

thin; thick

The stratum corneum is [thick/thin] in animals with thick, dense fur or hair, but [thin/thick] in humans

stratum corneum

The permeability of substance determined by _____

transepidermal

Barrier between stratum corneum and uppermost living layers associated with substance penetration to skin

transappendageal

Pilosebaceous apparatus (sebaceous gland, sebaceous gland duct, follicular epithelium) is associated with _______ substance penetration to skin

Transepidermal route: Intercellular

Is how a substance passes through lipid matrix around cells and this route is favored by drugs

Transepidermal route: Transcellular

What is the skin permeability route by which a substance can pass through the cell?

1. transepidermal (has 2 sub routes)

2. transappendageal

How do substances penetrate skin (2 methods)?

lipid

_____-soluble substances penetrate cell walls easil

cell membrane proteins

Water-soluble substances enter the skin via _____

-increasing temperature and increasing blood flow

-mechanical trauma

-Age → younger skin more permeable

-persistent hydration

How can we promote absorption of substances into the skin?

Size- small molecules penetrate easily

Lipid soluability→ Lipid soluable substances penetrate easily

Charge→ non-ionized substances penetrate easily

Contact time→ longer contact time may increase penetration

What are drug factors in regards to skin permeability

Aging

In regards to effects of sunlight on the skin what does UVA cause?

Sunburn + vitamin D

In regards to effects of sunlight what does UVB cause→

Filtered by atmosphere

In regards to effects of sunlight what happens to UVC

Opens into the hair follicle and secretes protein/ lipid rich

Structure and function of the sweat glands: Appocrine what does it open into and what does it secreate

function is phermones + or - cooling

distribution is in most domestic animals

structure and function of the sweat glands: Appocrine what does is its function and distribution

Opens into the skin surface

Secreation is watery

Function is cooling

Distribution is limited in many domestic species

structure and function of the sweat glands:In Eccrine what does it open into? what does it secreate? what is the Function? What is the distribution

Water, Na, K, Cl, urea, ammonia, lactic acid

Bacterial action on sweat creates odor

What does sweat contain?

Warmed blood from the periphery arrives at the brain and then stimulates the hypothalamic thermoregulatory center

Then the afferent nerve impulses from the periphery stimulate the thermoreregulatory center in the brain via a reflex mechanism

how does themoregulatory sweating work

Hair follicles

What are sebaceous glands associated with

Sebum and fatty lubricant

What does the sebaceous gland secreat

It is a modified sebaceous gland that has no defined duct. The substance that is produced is used as a territorial marker

What is the perianal/ circumanal glands of dogs

Wool and hair follicles

In sheep what is the sebaceous gland associated with

highly developed glands in the perianal region, horn, hoof, and muzzle margins

In cattle sebaceous glands are associated with

Stimulate testotrone and androgens

secreation is continuous

Phermone odors

waterproofing

luster to hair coat

antimicrobial activity

What are the functions of sebum

true

Sweat helps remove body heat. True or false?