Integumentary System Flashcards
What is the integumentary system?
The skin and its adnexal structures (hair and glands), horns, hoofs, claws, and other epithelial modifications
What molecule in the integumentary system helps it to act as a protective barrier?
Keratin
In what ways does the integumentary system act as a protective barrier
It reduces water loss, invasion by microorganisms, and abrasive trauma
What is skin?
An outside covering of an animal
What is skin continuous with?
Mucous membranes in the oral, anal, and urogenital orifices
Vestibule (inside) of the nostril
Palpebral fissure (area between eyelids)
What are the three layers of the skin?
Outer epidermis, the dermis, and the subcutaneous layer
What is the outer epidermis?
The layer we can touch
Describe the structure of the tissue that makes up the outer epidermis.
Keratinized, stratified, squamous epithelium
Why does the outer epidermis being stratified help
It allows for shedding and replacement of skin cells
What is the dermis?
The layer that hair and sweat glands originate from
Describe the structure of the tissue that makes up the dermis.
Dense, fibrous, vascular, connective tissue
What is the subcutaneous layer?
The hypodermis/bottom layer of skin
What is contained within the subcutaneous layer and what is its purpose?
Adipose/fat tissue
It insulates and absorbs shock
What determines how much adipose is in the subcutaneous layer?
The species of the animal
What is skin characterized by?
The mucocutaneous junction
In what two ways can skin thickness differ?
The species and the location on an individual
Where on an individual is skin the thickest?
Where it is the most exposed, like the back
Where on an individual is the skin the thinnest?
Where it is more protected, like the groin
How does skin adherence to structures beneath it vary?
By location on the individual
What are the three types of subcutaneous injections and what are the angles that they enter the skin at?
Intramuscular 90 degrees, subcutaneous 45 degrees, intradermal 10-15 degrees
What does an intramuscular injection penetrate and what is special about this kind of injection?
It penetrates the muscle
The length of the needle will vary based on species due to the varying thickness of adipose in the subcutaneous tissue that the needle has to pass through to reach the muscle
What does a subcutaneous injection penetrate?
The subcutaneous tissue
What does an intradermal injection penetrate?
The dermis
Where is the blood supply in the skin?
Only at the most basal layer of the epithelium/epidermis to help aide with production of new cells, which die off when they get further from the blood supply
What is the stratum corneum?
The most superficial layer of the epidermis that consists of layers of dead, flattened cells and has a smooth texture
What is the stratum lucidum?
A small layer of poorly stainable cells below the stratum corneum that is not always present
What is the stratum granulosum?
The layer below the stratum corneum (and stratum lucidum) that consists of spindle-shaped cells full of basophilic keratohyalin granules
What is the function of keratohyalin granules in the cell?
The cells in the stratum granulosum fill up with them, which kills the nucleus and causes the cytoplasm and organelles to go away, leaving the cells with no way to reproduce, so they dieI
What is the stratum basale?
A mitotically active layer of cuboidal or columnar cells that follow the shape of the dermis below it because it’s closely attached
Why is the stratum basale mitotically active?
Because it’s making cells to replace the cells that are dying off and being replaced
Where is the dermis in relation to the epidermis?
Below it
What are most of the cells in the epidermis?
Keratinocytes
What is a melanocyte?
A cell attached to the dermis that produces melanin, or pigment, that is absorbed into keratinocytes and provides protection from UV raysFr
What is a Merkel cell?
A cell close to nerve endings in the epidermis that contains hormones
What makes dead cells tough?
They’re filled with keratin
What happens to epidermis cells as they move further away from nutrients?
Cells flatten and die, but they leave a dense mat of their primary constituent- keratin
What is the process of drying and hardening the superficial cells called and what does it do?
Keratinization and cornification
It allows the skin to be tough and resistant while drying
What does the dermis contain?
Blood, sensory nerves, and glands
How does the dermis interact with the epidermis?
It interdigitates (interweaves) itself with the epidermis
What are the dermal papillae?
The dermal papillae are the interdigitating parts of the epidermis
What type of tissue makes up the dermis?
Fibrous connective tissue
What is the function of the dermis?
To support and strengthen skin
What is the papillary layer?
The layer containing the dermal papillae
What is the reticular layer?
The layer below the reticular layer that consists of 80% dense, irregular connective tissue
How do melanocytes interact with the dermis?
The melanin they produce is stored in melanosomes
What is a blister?
A disruption between the epidermis and dermis at the dermal papillae
How is a blister formed?
Epidermis is forced in a direction it’s not supposed to go, and the dermis isn’t made to go with it, so it rips
What is a callus?
Thickened stratum corneum
How does a callus form?
Repeated blisters prompts a thicker layer to form to help protect the dermis
Is the hypodermis a true layer?
No it’s a subcutaneous fat
What does hypodermis do?
Separates skin from muscle
What does the hypodermis have a lot of?
Connective tissue
What is the main type of tissue found in the hypodermis?
Areolar connective tissue
What is the variable amounts of fat in the hypodermis called?
Panniculus adiposus
What makes up paw pads?
Thick, tough skin with a thick layer of stratum corneum covering layers of fat and connective tissue
What does the increased adipose in paw pads do?
Provides a cushion
What are the purpose of paw pads?
Provide protection and reduce noise so predators can sneak up on prey
What is the planum nasale?
The top of the nose
The muzzle in horses and cows
How do different species keep the planum nasale moist?
In dogs, it is not glandular and is kept wet through nasal secretions and licking
In cows, sheep, and pigs, it is glandular with the glands keeping it moist
What are the three types of hair?
- Primary/Guard hairs
- Secondary/Undercoat/Wool hairs
- Tactile hairs