Integument Physiology I Flashcards
What are the three layers of the skin (from outermost to innermost)?
Epidermis, dermis, hypodermis
What are the 4 distinct cell types of the epidermis? Most common?
Keratinocytes*, Merkel cells, Langerhans, Melanocytes
What are melanocytes responsible for?
They are responsible for the production of melanin this pigmentation of skin and hair
What are keratinocytes? Layers thick?
Specialized epithelial cell (most common)
2-5 layers
What are Langerhans cells?
Macrophages involved in immunity?
What are Merkel cells?
Sensory cells involved in perception
Composition of dermis layer?
Connective (tough and strong), has inherent flexibility
What is the dermis composed of?
Insoluble fibers
Soluble polymers
Macromolecules
Function of Soluble polymers?
Resist tensile forces
Function of macromolecules?
Resist compressive forces
What does the dermis contain?
Hair follicles, sebaceous/sweat glands, arrector pili m., lymph vessels, nerves
Hypodermis layers also called?
Subcutaneous layer
Functions of dermis?
Regular cell growth, proliferation , adhesion, migration, differentiation, wound healing. structure/function of epidermis
Which skin layer is thickest?
Hypodermis
What parts of the body do not have hypodermis?
Lips, anus, external, ear, eyelid, cheek
What does hypodermis mostly consist of?
Triglycerides
Functions of hypodermis?
Energy reserve
Thermogenesis/Insulation
Padding/support
Surface contours
Steroid reservoir (estrogen/metabolism production)
What function of skin is the most important?
Physical barrier
What are the six functions of the skin?
- Physical barrier
- Thermogenesis
- Metabolic Functions
- Immune Defense
- Indicator
- Sensory Perception
What is the primary role of the SQ layer? Hairs? Glands?
Cushioning; frictional injury; physical defense
What specifically is skin a physical barrier to?
water, electrolytes, macromolecules
What types of injurious agents does skin keep out?
Physical, chemical, microbiota
What processes of the skin contribute to its physical barrier function?
Melanin formation (prevents sun damage and camouflage), vascularity, keratinization
What is skin the first defense to?
The outside world
What substances provide antifungal/microbial properties?
Lipids, acids, lysozymes, peptides
What is the general pH of skin?
Acidic
What is the adaptive immunity regulated by?
Lymphocytes
What is skin an indicator of?
Health, internal disease, communication
What prevents BAD microbiota?
Diverse population of microorganisms
What types of cell can move towards the skin?
Leukocytes
What can skin communicate?
Camouflage, olfactory cues, sexual dimorphism
CR: Hairloss can help diagnose what?
Hairloss –> Alopecia –> Hypothyroidism
What senses is the skin responsible for?
Touch, pressure, pain, itchiness, heat/cold
What is responsible for sensation in the dermis? Epidermis?
Somatic sensory nerve fibers; Merkel cells
What is proprioception?
The sense of movement, action, and location
What are the 3 metabolic functions of the skin?
- Storage of nutrients/fluid
- Excretion of toxins
- Vit D metabolism
What is the skin a reservoir for?
Macromolecules
What is an example of fat deposition in species?
Camel
How does the skin excrete toxins?
Sweating and skin secretions through sebaceous glands
What are the two ways for Vit D metabolism?
- Diet
- Photosynthesis
What are the functions of Vit D?
- Calcium/phosphorous homeostasis
- Skin epidermal proliferation and differentiation
- Pregnancy/immunity
What is the pathway of Vit D metabolism through diet?
Gut to Liver
to Kidney
Describe the pathway of Vit D metabolism through photosynthesis?
Solar radiation and pro vitamin D3 and pre vitamin D3
MAKES
Vit D3
Vit D3 and VD binding protein
GO INTO CIRCULATION TO THE LIVER
Liver hydroxylates D3 into calcidiol
HEADS TO Kidney
Hydroxylates Calcidiol to Calcitrol (ACTIVE FORM OF VIT D)
How does the skin contribute to thermoregulation?
Support the haircoat
Regulates blood supply
Sweat gland function
Examples of protection against cold?
Haircoat
Hypodermis
Skin Pigmentation
When the temperature decreases, what physiological responses increase?
Piloerection
Cutaneous vasoconstriction
Shivering
Non-shivering thermogenesis
Describe piloerection.
Involuntary response of pili mm. which increases haircoat volume and traps air
Describe cutaneous vasoconstriction.
Blood vessels close, pushing blood to the core
What is the critical temp?
External temp at which heat maintaining mechanisms no longer work so thermogenesis is required
Why are non-shivering mechanisms required?
In cold environments, need extra support
Particularly for young and hibernating animals
Describe shivering.
Muscle activity increases
What are the 4 mechanisms of heat loss?
- Conduction
- Radiation
- Convection
- Evaporation
What is utilized in non-shivering thermogenesis?
Brown fat
What is the most effective physiological response to heat loss?
Shivering
What is the CT for dogs with hair?
No hair?
57 F
77 F
What is conduction? Example?
heat transfer to object lying on (cool surface)
What are behaviorial responses to heat loss?
Heat seeking
Increase in activity
Compact posture
What is radiation?
Animal to local environment
What is convection? Example?
Movement of air (breeze)
What is a cat specific heat loss behavior?
Watery saliva from submaxillary glands (grooms to spread)
What is evaporation?
Sweating, panting, grooming
What detects an increase in temperature in the brain?
Hypothalamus
When does a cats rectal temperature increase?
90 F
What are dogs CT for increase in temperature?
Low 80’s
How does heat affect cat’s breathing? CR?
Breathing volume only slightly decreases so susceptible to a decrease in CO2 (alkalosis)
What happens to dog’s breathing when temperature increases?
Increases breathing, depth decreases to prevent excess CO2
When does a dog reach thermal imbalance? Collapse?
105 F; 109 F
What is the efficiency of heat loss based on?
Humidity AND temperature
What are the physiological heat loss responses?
Cutaneous vasodilation
Increase evaporative losses
Explain cutaneous vasodilation.
blood vessel size increases
Examples of evaporative losses?
Sweating, panting, grooming
What do carnivores lack for evaporative loss?
Atrichial sweat glands (only have eccrine pads)
Explain mechanism of panting.
Carnivores vaporize water via respiration
What are heat loss seeking behaviors?
cold seeking behavior
limiting activity