Integument Physiology I Flashcards by Hanna Barrett

What are the three layers of the skin (from outermost to innermost)?

Epidermis, dermis, hypodermis

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What are the 4 distinct cell types of the epidermis? Most common?

Keratinocytes*, Merkel cells, Langerhans, Melanocytes

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What are melanocytes responsible for?

They are responsible for the production of melanin this pigmentation of skin and hair

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What are keratinocytes? Layers thick?

Specialized epithelial cell (most common)
2-5 layers

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What are Langerhans cells?

Macrophages involved in immunity?

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What are Merkel cells?

Sensory cells involved in perception

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Composition of dermis layer?

Connective (tough and strong), has inherent flexibility

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What is the dermis composed of?

Insoluble fibers
Soluble polymers
Macromolecules

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Function of Soluble polymers?

Resist tensile forces

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Function of macromolecules?

Resist compressive forces

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What does the dermis contain?

Hair follicles, sebaceous/sweat glands, arrector pili m., lymph vessels, nerves

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Hypodermis layers also called?

Subcutaneous layer

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Functions of dermis?

Regular cell growth, proliferation , adhesion, migration, differentiation, wound healing. structure/function of epidermis

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Which skin layer is thickest?

Hypodermis

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What parts of the body do not have hypodermis?

Lips, anus, external, ear, eyelid, cheek

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What does hypodermis mostly consist of?

Triglycerides

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Functions of hypodermis?

Energy reserve
Thermogenesis/Insulation
Padding/support
Surface contours
Steroid reservoir (estrogen/metabolism production)

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What function of skin is the most important?

Physical barrier

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What are the six functions of the skin?

Physical barrier
Thermogenesis
Metabolic Functions
Immune Defense
Indicator
Sensory Perception

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What is the primary role of the SQ layer? Hairs? Glands?

Cushioning; frictional injury; physical defense

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What specifically is skin a physical barrier to?

water, electrolytes, macromolecules

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What types of injurious agents does skin keep out?

Physical, chemical, microbiota

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What processes of the skin contribute to its physical barrier function?

Melanin formation (prevents sun damage and camouflage), vascularity, keratinization

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What is skin the first defense to?

The outside world

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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?

1. Storage of nutrients/fluid 2. Excretion of toxins 3. 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?

1. Diet 2. Photosynthesis

What are the functions of Vit D?

1. Calcium/phosphorous homeostasis 2. Skin epidermal proliferation and differentiation 3. 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?

1. Conduction 2. Radiation 3. Convection 4. 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