Unit 2 - Integument Flashcards
What does the integument consist of?
Skin/hide, sweat and oil glands, hair, hooves, horns
What is the definition of homeostasis?
The state of steady internal, physical chemical and social conditions maintained by living systems
What is surface epithelium?
Sheets of cells covering the external surface of the body
What are the functions of the integumentary system?
- Protect the body from: invasion of microbes, insects, external parasites and exposure to environmental chemicals and ultraviolet radiation
- Protects from abrasion, rubbing, scratching and animals contact with the ground and surrounding environment
- Protects the body from dehydration by keeping moisture on the skin or sweat based on enviro. Conditions to maintain homeostasis
- Maintain body temp via sweat, cutaneous blood flow and hair coat
- Detection of sensory information (touch and pressure)
- Transferring information to the central nervous system
- Excretion of organic waste and excess of salts
- Metabolic actions - synthesizes vitamin d
What is required to maintain proper nutrition due to loses of energy from temp?
Lots of energy is needed to maintain body temperature and therefore a proper diet that ensures nutritional requirements are being met is important
Where does vitamin D3 synthesis take place in the integument?
On all areas of the skin and is not exclusively located on skin areas where hair coverage is lacking
What is the skin?
Covers what most of us would consider the outside of the animal, skin has the ability to regenerate and heal, adaptation of the hide include horns and toes
Where does skin tend to be the thickest on the body?
In regions where there is the greatest exposure to the environment and tends to be thin in areas where the animal is protected, may be tightly attached to underlying structures or may be loosely attached to allow considerable movement?
What are the three layers that the skin is composed of?
Epidermis, Dermis, Hypodermis
What are some features of the epidermis?
- Formed by layers of flat cells - cells are not live, but come from live cells
- Made of squamous epithelium
- There are no blood vessels found in this layer
- Free of nerve endings
- Nutrients must diffuse from capillaries located in the underlying dermis to meet nutrient requirements of epidermal cells
What are the different stratum layers in the epidermis?
Stratum basale -> Stratum spinosum -> Stratum granulosum -> Stratum lucidum -> Stratum corneum
What two layers of the stratum epidermis are only found on non-hairy skin?
Stratum granulosum -> stratum lucidum
Where are the live cells found on the epidermis?
Stratum basale, and then slowly die as they move up and proliferate
What type of cell is the epidermis made out of?
keratinocytes (most common cell in the epidermis)
How does cell division occur in the epidermis?
Because the basale is adjacent to the blood vessels in the dermis, there are adequate nutrients to support cell division by mitosis?
What does keratin in the epidermis do?
Protects the skin against pathogens
Which layer is keratin produced in the epidermis?
Stratum granulosum, keratin rich as surface of skin approaches
What does the stratum basale do?
Deep germinative layer of the epidermis, composed of single layer of cuboidal cells
What is the function of stratum spinosum?
Cells as polyhedral to slightly flattened, 2-4 layers
What is the stratum granulosum?
Composed of flattened cells, with shrunken nuclei. Contains keratin granules, precursors for keratinization
What is the stratum corneum?
Provides a removal of surface pathogens (renewed cont.), contains antimicrobial peptides and lipids which defend the skin - aid in bacterial and chemical defense
What do cells loose as they move up the epidermis?
Lose nuclei, cytoskeleton and organelles
What do dead cells have their content replaced by?
Protein keratin, waterproof the skin and protect from water loss
What is the process of keratinization and hardening?
The cells are exposed to the environment dry out and become harder, while these cells are dead, the keratin has a protective function to make the skin tough and resistant
How does the epidermis shed?
Sheds on daily basis with millions of cells shed per day
What are langerhan cells?
Present in the epidermis, they detect invaders such as foreign debris or microorganisms and phagocytize them (work as a macrophage), they act as immune cells, and determine the appropriate immune response
What are melanocytes?
Present in the epidermis, responsible for producing the pigment melanin which protects cells from ultraviolet radiation