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
What is a merkell cell?
Present in the epidermis, function as sensory receptors to touch and are found at the epidermal/dermal junction
What is the function of the dermis?
Provides structural strength and flexibility of skin
How is the dermis so strong?
High amounts of collagen, elastin, reticular fibres produced by fibroblasts, the collagen is responsible for strength, elastin is responsible for strength and resistance, the reticular fibres are responsible to join connective tissue to other tissues
What are some features of the dermis?
- composed of dense irregular connective tissue - find hair follicles, nerve endings, glands, blood vessels and lymphatic channels
- have blood vessels
- sensory receptors
What are the names of the connections between the epidermis and the dermis layers?
Epidermal ridges and the dermal papillae
What do the presence of blood vessels in the dermis do?
Provide nutrients to the epidermis and remove waste and regulate temperature (blood vessels increase or decrease in size based on temp.)
What is the purpose of the sensory receptors in the dermis?
Send information regarding the external environment to the CNS, have temperature change receptors, they contain meissner’s corpuscles (pain and touch receptors)
What are some features of the hypodermis?
- known as the subcutaneous fat layer
What is the hypodermis made up of?
- areolar connective tissue
- adipose tissue
- blood vessels
- lymphatic vessels
- nerves
- loose tissue
What is the function of the loose tissue/areolar tissue in the hypodermis?
- allow the skin to move without tearing, cushion and protect skin and muscles and organs, most common type of connective tissue
What can subcutaneous fat help with in terms of meat quality?
Meat colour but too much isn’t good
What is the function of the adipose tissue in the hypodermis
Acts as shock absorber and thermal insulator, source of energy for animal during fasting
What is the function of the blood vessels in the hypodermis?
Appear in large number, associated with adipose tissue deposition and mobilization, increase in lipid deposition in fat tissue, mobilization of lipids from at tissue to supply energy source
The subcutaneous fat is also known as…?
Fat cover
Where are sweat glands located?
Dermis or hypodermis
What are the two types of sweat glands?
Eccrine and apocrine
What is an eccrine sweat gland?
Is connected to the surface of the skin by a long duct, has its excretory portion as a simple coiled tube, they sweat and cool animal off
Do domestic animals have more eccrine or apocrine sweat glands?
Apocrine that open onto hair follicles
What is an apocrine sweat gland?
Empty into hair follicle and not onto skin surface, have a coiled excretory portion
What is the secretion that an apocrine sweat glans produces?
Water, fatty acids and proteins combined with oily secretions from the sebaceous gland which produces the characteristic odor of dogs, horses, cattle
Which species have larger sweat glands, Brahman or angus?
Brahman due to the temperature adaptation, they need to sweat more in order to maintain body temp, however angus have thicker epidermis and dermis
How does temperature regulation in the skin work?
Changes in blood flow through skin capillaries alters the amount of warm blood near the body surface, increasing the amount of blood near body surface enables animal to dissipate heat to help cool themselves
What are the function of oil glands?
Releases secretion onto hair follicles or to skin surface, they degrade epithelial cells to produce lipid based sebum
What is the function of sebum?
Keep hair from becoming fragile, (traps moisture), prevents excess evaporation of moisture from skin, keeps skin soft, has anti fungal properties
What is the structure of the hair follicle?
Shaft: part of the hair visible above the skin
Root: Part buried within the skin
Hair follicle: invagination of the epidermis that extends from skin surface to dermis
Hair bulb: formed but he expansion of the deepest part of the hair follicle
Papilla: mound of dermal cells covered with matrix
Matrix: rapidly dividing epithelial cells
What is a primary hair follicle?
Have a large diameter, rooted more deeply, associated with sweat glands and arrest or pili muscle
What is a secondary hair follicle?
smaller in diameter, more superficially rooted, have a sebaceous gland but lack sweat gland and arrector pili muscle (help hair stand on ends)
What is a simple hair follicle?
Single hair emerges from a singular orifice
What is a compound hair follicle?
Multiple hair emerges from a singular orifice, each hair have their own papilla
How does hair production occur?
Occurs at the base of the follicle, matrix cells are nourished by blood flow from vessels which stimulates proliferation, older cells are pushed up, cells die and become keratinized
What are the three phases of the hair cycle?
Anagen phase - growing period, genetically predetermined
Telogen phase - Can last for weeks to years, dormant
Catagen phase - dying period, growth stops and hair follicle detaches form dermal papilla cells and falls
What is the hoof?
Extension of skin front the lower limbs, the hoof has continuous growth
What is the function of the hoof?
Maintain good traction, defence against predators
What is the hoof made from?
Ungula
What is the structure of the hoof?
- outer layer is cornified - insensitive to pain
- underneath is the coronary horn - contains blood vessels, supplies nutrients and can sense pain
Why do horses wear shoes?
Strengthens the foot
Increases integrity of the hoof
Provides traction
Barrier between hoof and ground
Provides a barrier between the hoof and the ground
Why must hoof’s be trimmed?
Prevent lameness
What is the structure of the horn?
Germinal center is found on the frontal bone, this core is covered by dermis, the horn elongates from this core base
What is the horn made from?
Dense keratin
What is the horns growth influenced by?
- nutrition
- sex: females have smaller horns or no horns
- species
- genetics: polled or not polled
What are the two types of methods of horn removal?
- surgical removal of horn button
- destruction of horn button using hot iron or caustic paste
Two sections of the dermis?
Papillary layer: loose connective tissue
Reticular layer: dense irregular connective tissue
