Skin Flashcards
Body Membranes
Covering and lining membranes
Function of body membranes
- Cover the surface
Cutaneous membrane (skin) - Line body cavities
Mucous membrane - line body cavities that open to the exterior (nose/ digestive tract/ inside lining of the lungs) - line organs, forming protective sheets around them and often providing lubrication to reduce friction
Serous membranes line body cavities closed to exterior (outside lining of the lungs)
Classification of body membranes
- Epithelial membranes (cutaneous/ mucous/ serious membranes)
- Connective membranes (synovial membrane)
Epithelial membranes are known as
Covering and lining membrane
Types of epithelial membranes
Cutaneous membrane
Mucous membrane
Serous membrane
Epithelial membrane
each of these membranes contains an epithelial layer combined with an underlying layer of connective tissue.
Layers of Cutaneous membrane
Superficial epidermis (stratified squamous epithelium)
Underlying dermis (dense connective tissue)
True or False
The cutaneous membrane is exposed to air and is considered a dry membrane.
True
Mucous membrane consist of
• Epithelium (the type varies depending on the location(stratified squamous/ simple columnar))
• Lamina propria (loose connective tissue)
• Muscularis mucosae
Type of epithelium in the mucousae membrane
Stratified Squamous (mouth/ esophagus)
Simple Columnar (rest of the digestive tract)
True or false
The mucousae membrane is a dry membrane
False
Mucosae are typically moist membranes that are continuously bathed in secretions, such as mucus or urine.
Function of the epithelium mucousae membrane
Absorption and secretion
While many mucosae secrete mucus, not all of them do. For example, the mucosae of the respiratory and digestive tracts secrete protective, lubricating mucus, whereas the urinary tract’s mucosa does not.
Serous membrane
Simple squamous epithelium
A thin layer of areolar connective tissue
Layers of serous membrane
Serous membranes occur in pairs.
The parietal layer lines a specific portion of the ventral body cavity wall. It folds in on itself to form the visceral layer, covering the organ(s) in that cavity.
The layers are separated by serous fluid, which allows rhe organs to slide past each other without causing friction, especially in mobile organs (lung, heart)
Peritoneum
The serosa lining the abdominal cavity and covering its organs is the peritoneum
Membranes of the heart and lungs
Membranes around the lungs are pleura.
Membranes around the heart are pericardium.
Synovial membranes are composed of
Loose areolar connective tissue
Synovial membranes function
- Their primary function is to line the fibrous layer surrounding joints.
- They provide a smooth surface within joints.
- They secrete a lubricating fluid that reduces friction within the joint.
Integumentary system consist of
Skin
Appendages
Function of the integumentary system
Protect tissues from different types of damages (mechanical/ chemical/ microbe/ UV/ thermal/ desiccation)
Aids in body heat loss
Aids in excretion of urea and uric acid
Synthesis of vitamin D
Protects deeper tissues from mechanical damage (bumps)
Presence of keratin ——> toughens cells
Fat cells ——> cushion blows
Pressure and pain receptors ——> alert nervous system to possible damages
Protects deeper tissues from chemical damage (acids and bases)
Has relatively impermeable keratinized cells; contains pain receptors, which alert the nervous system to possible damages
Protects deeper tissues from microbe damage
Unbroken surface
Acid mantle (skin secretions are acidic, so they inhibit microbes, such as bacteria)
Phagocytes - ingest foreign substances and pathogens
Protects deeper tissues from ultraviolet (UV) radiation (damaging effects of sunlight or tanning beds)
Melanin produced by melanocytes offers protection from UV damage.
Protect deeper tissues from therma damage (heat/ cold)
Contain heat/ cold/ pain receptors
Protect deeper tissues from dessication (drying out)
Contains a water-resistant glycolipid and keratin
Aids in body heat loss or heat retention (controlled by the nervous system)
Heat loss: By activating sweat glands and allowing blood to flush into skin capillary beds so that heat can radiate from the skin surface.
Heat retention: By not allowing blood to flush into skin capillary beds.
Aids in excretion of urea and uric acid
Contained in perspiration produced by sweat glands.
(The skin excretes different types of waste products in sweat)
Synthesizes vitamin D
Modified cholesterol molecules in skin converted to vitamin D in the presence of sunlight.
Structure of the skin
Epidermis
Dermis
Hypodermis
Epidermis tissue
Stratified Squamous epithelium
Function of epidermis
It is capable of keratinization, making it hard and tough.
Dermis tissue
Dense connective tissue.
Function of the dermis layer
Connects the skin to fat and muscle
Blisters
Caused by a burn or friction, seperating the epidermis and dermis layer, allowing interstitial fluid to accumulate in it
Hypodermis
Made of adipose tissue (fat)
Function of the hypodermis layer
Functions of the subcutaneous tissue:
1. It anchors the skin to underlying organs
2. It provides a site for nutrient (fat) storage
3. It serves as a shock absorber
4. It insulates the deeper tissues from extreme temperature changes occurring outside the body.
Most cells present in the epidermis
Keratinocytes
Keratinocytes
responsible for producing protein keratin, a fibrous that toughens theepidermis through keratinization.
Keratinocytes
Keratinocytes are connected throughout the epidermis by desmosomes
Epidermis characteristic
The epidermis is avascular,meaning it lacks its own bloodsupply.
(This explains why shaving daily does not cause bleeding despite removing multiple cell layers.)
Five layers of epidermis (from the inside to the outside)
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidumin (found only in thick skin)
- Stratum Corneum
Stratum Basale
The stratum basale is the deepest layer of the epidermis.
It lies closest to the dermis and, therefore, it is well nourished.
Composed of basal keratinocyte stem cells (divide constantly) and then forming the keratinocytes of the stratum spinosum as they migrate superficially.
Cells within the stratum basal
