Week 1: Skin and Fascia Flashcards
What are the 3 types of connective tissue proper?
- Adipose tissue ( fat )
- Loose connective tissue (fascia)
- Dense regular tissue ( tendons and ligaments )
What are the 2 specialised connective tissues?
- Cartilage
- Bone
What are the functions of connective tissue?
Support, anchor & connect various parts of the body
What are the layers of the tissue from out to in?
- Skin
- Superficial fascia (hypodermis)
- Deep fascia
- Muscle
- Bone
What are the 3 layers of the skin from out to in?
- Epidermis (epithelium)
- Dermis (connective tissue)
- Hypodermis/subcutis (connective tissue)
Describe the function and 4 features of the epidermis:
- Squamous epithelial tissue
- Keratinised
- Self-regenerating
- Avascular
* Function: protection
Describe the 4 features of the dermis:
- Fibro-elastic connective tissue (dense)
- Densely packed collagen and elastin in an irregular arrangement - Tough, supporting and nourishing layer
- Contains most of the sensory nerve endings and other ‘appendages’
- Contains blood vessels, nerves and sensory receptors
Describe the function and 5 features of the hypodermis/superficial fascia:
- Inner layer, between skin and muscle
- Attaches dermis to underlying tissue
- Mainly adipose tissue surrounded by collagen (loose irregular connective tissue)
- Contains sensory receptors
- Contains the larger vessels which supply and drain the dermal blood vasculature
* Function: shock absorption, insulation, passage for nerves and blood vessels
Describe 4 skin appendages:
- Hair: Sensory and thermoregulation
- Sweat glands: Thermoregulation
- Sebaceous glands: Produce sebum, epidermal barrier
- Nails: Protect the tips of the fingers and toes and supports the grasping function of the fingers
How do different burns affect the layers of the skin?
First-degree burn: Only epidermis affected - sunburn
Second-degree burn: Epidermis and dermis affected - note blister
Third degree burn: All 3 layers affected
Name the 2 sensory innervation systems in the skin:
- Efferent - going from the brain (autonomic), supply is from sympathetic nervous system
- Afferent - ingoing to the brain (somatic)
Name the 3 efferent innervations of the skin?
- Blood vessels
- Arrector pili muscle
- Sweat glands
What types of blood vessel functions are controlled by the efferent nerve supply?
Controls blood vessel diameter and hence blood flow – important for temperature control (vasoconstriction and vasodilation)
What lifestyle factors may influence the microcirculation of the skin?
Physical activity, diet and smoking, together with increasing age
Name the 3 afferent innervations of the skin:
- Free nerve endings - Simplest form of sensory receptor, myelinated or unmyelinated
- Meissner corpuscles - small, encapsulated spiral of nerve cells
- Pacinian corpuscles - large, encapsulated mass of nerve cells
Where are free nerve endings found and what type of sensory input do they receive?
- Epidermis and dermis
- Pain, itch, temp
Where are meissner corpuscles found and what type of sensory input do they receive?
- Dermal papillae - prevalent in sensitive areas of skin e.g. lips, fingers
- Small & for light touch
Where are pacinian corpuscles found and what type of sensory input do they receive?
- Deep in dermis and hypodermis - particularly prevalent in fingertips
- Pressure and vibration
What are the 4 main functions of the skin?
- Protection: against UV, mechanical, chemical and thermal insult; prevention of dehydration; barrier to microbial invasion.
- Sensation: touch, pressure, pain, and temperature receptors
- Thermoregulation: hairs, subcutaneous fat, sweat glands, blood vessels
- Metabolic functions: energy storage in hypodermic fat; Vitamin D synthesis in epidermis
What is meant by classifying the epidermal layer of skin as ‘thick’ or ‘thin’?
It refers only to the depth of the epidermal layer, not to the overall thickness of the skin
Where in the body do you find thick skin? Why do you think these areas are covered in thick skin?
- Palms of the hands and soles and toes of the feet
- Skin is subjected to considerable frictional and shearing forces in these areas, particularly the feet with walking
How much does skin contribute to the bodies total body mass?
Approximately 15-20%
Given its vascularity, what is an important role of the dermis?
Important for thermoregulation - adjustments to blood circulation in order to conserve or lose heat
What are sweat glands?
Simple, coiled, tubular glands, which secrete sweat onto the skin surface via ducts
What is the function of sweat?
Thermoregulation - Increased sweat production leads to cooling of the skin via evaporation of sweat
Why is there variation in the amount of adipose tissue in superficial fascia?
Variation due to location (e.g. fat pads in heel of foot) for shock absorption
Is superficial fascia designed to transmit force?
No - mostly comprised of loose connective tissue, to allow structures to move on one another
What are the 2 main functions of the lymphatic system?
- Return excess interstitial fluid back to the venous circulation and therefore maintain fluid balance
- Contribute to immunity (contains immune cells as part of the defense against microorganisms)
What is fascia and what does it do? Include its main function.
- Connective tissue containing varying amounts of fat
- Separate, support, and interconnect organs and structures
- Enable movement of one structure relative to another
- Transit of vessels and nerves
Function:
Limit the spread of infection and malignant disease. Extensive dissection – when infection crosses fascial plain
What are the 2 categories of fascia?
- Superficial fascia
- Deep fascia
Describe the 5 features of superficial fascia:
- Also referred as the hypodermis/subcutaneous layer
- Loose connective tissue
- Significant layer of fat = heat insulation
- Conveys blood vessels to and from the skin
- Promotes movement between the skin and underlying structures e.g., dorsum of hand
Describe the feature and 4 functions of deep fascia:
Dense irregular connective tissue - ensheaths muscle or viscera
Functions:
1. Decreases friction
2.Divides (intermuscular septa) limbs into compartments (muscles in a compartment tend to share a common nerve and blood supply)
3. Enables venous return via ‘muscle pump’
4. Protection
What is compartment syndrome?
Increase in pressure within a defined compartment of the limb, demarcated by a fascia.
↑ intra-compartmental pressure, ↑ pressure on arteries – ↓ perfusion pressure, leading to hypoxemia of the tissues
