Integumentary System Flashcards
What does the term “integumentary system” refer to?
All the structures and tissues related to the skin and accessory organs
What does the skin include?
Epidermis and dermis
What are the accessory organs in the integumentary system?
Hair, nails and glands such as subcutaneous and sweat glands
What is controversial regarding the integumentary system?
It has many elements but is not regarded as a system in medicine
What are the four main tissue types regarding the human body?
Epithelial: covers body surfaces and lines body cavities
Connective: binds and supports body parts
Muscular: moves body parts
Nervous: receives, interprets and sends signals
What are the features of epithelial tissue?
Covers whole surface of the body
Made up of cells that are closely packed and arranged in 1 or more layers
Tissue is specialised to form the covering or lining of all internal and external body surfaces
Epithelial tissue occurring on surfaces on the interior of the body known as the endothelium
Epithelial cells are packed together tightly, with no intercellular spaces and only a small amount of intercellular substance
Epithelial tissue (regardless of type) usually separated from underlying tissue by a thin sheet of connective tissue a.k.a. basement membrane
Basement membraneprovides structural supportfor the epithelium and alsobinds it to neighboring structures
What are the five types of epithelial tissue and where can they be found?
Squamous (flat): lungs and blood
Cuboidal (cube): kidney tubes
Columnar (pillars): digestive tract
Pseudostratified (ciliated columnar): respiratory tract
Stratified squamous epithelium (more than 1 layer, flat): oesophagus
What are the functions of the epithelium tissue?
Protection
Sensation
Secretion
Absorption
Excretion
Diffusion
Cleaning
Reduces Friction
How can the epithelial tissue provide protection?
Epithelial cells from the skin protect underlying tissue from mechanical injury, harmful chemicals, invading bacteria and from excessive water loss
How can the epithelial tissue provide sensation?
Sensory stimuli penetrate specialised epithelial cells
Specialised epithelial tissue containing sensory nerve endings is found in the skin, eyes, ears, nose and on the tongue
How can the epithelial tissue aid secretion?
In glands, epithelial tissue is specialised to secrete specific chemical substances such as enzymes, hormones and lubricating fluids
How can the epithelial tissue aid absorption?
Certain epithelial cells lining the small intestine absorb nutrients from the digestion of food
How can the epithelial tissue aid excretion?
Epithelial tissue in the kidney excrete waste products from the body and reabsorb needed materials from the urine
Sweat is also excreted from the body by epithelial cells in the sweat glands
How can the epithelial tissue aid diffusion?
Simple epithelium promotes the diffusion of gases, liquids and nutrients
Because they form such a thin lining, they are ideal for the diffusion of gases (e.g., walls of capillaries and lungs)
How can the epithelial tissue aid cleaning?
Ciliated epithelium assists in removing dust particles and foreign bodies which have entered the air passages
How can the epithelial tissue reduce friction?
Smooth, tightly-interlocking, epithelial cells that line the entire circulatory system reduce friction between the blood and the walls of the blood vessels
What causes skin to sag?
Gravity weighing down- constant downward pull on faces, shoulders, backs, necks, chests, organs, legs and feet cause skin to also drag down
How do populations respond to ageing?
Millions of dollars are spent every year to tighten sagging, drooping skin
Face lifts, Botox, creams, serums and muscle exercises have been developed as a counter method
How is epithelial tissue attached to the body?
Via the basement membrane
How does the basement membrane act as an anchor?
Attaches epithelium tissue to the connective tissue below
How many layers of the skin are there and what are their names?
Epidermis, Dermis and Subcutaneous
What are features of the epidermis layer?
Outer layer
Composed of epithelial cells
What are the features of the dermis layer?
Composed of connective tissue such as: blood vessels, sweat glands, sebaceous glands and temperature sensors
What are features of the subcutaneous layer?
Lowest layer
Where is the basement membrane located?
Lies between the epidermis and the dermis, keeping the outside layer tightly connected to the inside layer
What is a benefit of the basement membrane?
The skin will droop due to gravity but not fall off
Is the basement membrane located just in the skin?
No as it has functions around the entire body
How can the basement membrane be located?
Any place between the epithelium and endothelium layer as to hold the layers together
What is the basement membrane composed of?
Glycoproteins: sticky sugary proteins and protein fibres like collagen
What are the properties of collagen?
Strong and elastic-stretchy
What is the weight and covering of the skin on the body?
Skin weighs around 6 pounds, and covers more than 3000 square inches
Largest organ of the body and supplied with blood vessels and nerves
What are the benefits of the skin?
Covers the entire body and provides protection against injuries, infection, and toxic compounds
What is the role of nerve endings in the skin?
Act as receptors for pain, temperature, touch and pressure
What does epidermis mean?
On top of the skin
What are the features of the epidermis?
Is multilayered
Contains is superficial layer of dead skin cells called stratum corneum
The stratum corneum is composed of cells called keratin
Is avascular (no blood vessels)
Has no nerve tissue (can’t feel pain)
What are the two distinct layers of the dermis?
Papillary layer (more superficial)
Reticular layer (more deeper)
What are features of the dermis?
Accessory organs begin the dermis
Some of the accessory organs end or cross into the epidermis
Dermis contains blood vessels and nerve tissue
What are features of the subcutaneous fat?
Found deep to the dermis
Contains the larger blood vessels of the skin
Composed of adipose (fat) tissue, a form of connective tissue
What are some of the functions of the skin?
Provides protection against invasion by bacteria and other harmful agents- protects delicate cells beneath the surface from injury
Inhibits excessive loss of water and electrolytes
Produces a protective pigmentation to protect the body against excessive exposure from the sun
Helps produce the body’s supply of Vitamin D
What is the fascial layer?
Deep to the subcutaneous layer
Covers the muscles beneath
What are further functions of the skin?
Homeostasis
Vasoconstriction or vasodilation:
The skin regulates body temperature- when the body is too cold, the skin’s blood vessels constrict, this allows more heat-carrying blood to circulate to the muscles and organs
When the body is too hot, the blood vessels in the skin dilate. That brings more blood to the surface for cooling by radiation. At the same time, sweat glands secrete more sweat that cools the body when it evaporates
How does the skin interact with the brain to co-ordinate sensation?
It contains millions of nerve endings that act as sensory receptors for pain, heat, cold, and pressure. When stimulation occurs, nerve impulses are sent to the cerebral cortex of the brain… and the brain triggers any necessary response
What is the average surface area that the skin covers on an adult?
Average surface area of between 1.5-2.0 square metres (16.1-21.5 square feet), most of it between 2-3mm thick (0.10 inch thick)
On average weighs around 9 pounds
What does the average square inch (6.5 cm squared) of skin contain?
650 sweat glands
20 blood vessels
60,000 melanocytes
More than 1000 nerve endings
What are the functions that the skill can perform?
Protection: an anatomical barrier from pathogens and damage between the internal and external environment in bodily defense;
Sensation: contains a variety of nerve endings that react to heat and cold, touch, pressure, vibration, and tissue injury
Heat regulation: Dilated blood vessels increase perfusion and heat loss, while constricted vessels greatly reduce cutaneous blood flow and conserve heat
Control of evaporation: the skin provides a relatively dry and semi-impermeable barrier to fluid loss.
Loss of this function contributes to the massive fluid loss in burns
Aesthetics and communication: Some trained professionals see our skin and can assess our mood, physical state and attractiveness
Storage and synthesis: acts as a storage center for lipids and water, as well as a means of synthesis of vitamin D by action of UV on certain parts of the skin
Excretion: sweat contains urea, however its concentration is 1/130th that of urine, hence excretion by sweating is at most a secondary function to temperature regulation
Absorption: the cells comprising the outermost 0.25–0.40 mm of the skin are “almost exclusively supplied by external oxygen”, although the “contribution to total respiration is negligible”
Water resistance: The skin acts as a water resistant barrier so essential nutrients aren’t washed out of the body
What is significant about the epidermis?
It has 4 strata
What is the name of the outermost strata of the epidermis and what is it comprised of?
Stratum corneum
Mostly dead cells, as well as dying cells, filled with a protein substance called keratin
How does pressure affect the stratum corneum?
It is thicker on the soles of the feet than on the eyelids, which is where there is less pressure
What is the layer beneath the stratum corneum called, and what are some of its features?
Stratum lucidum
Translucent layer directly beneath the corneum
May not even exist in thinner skin
Cells in this layer are also dead or dying
What is the layer beneath the stratum lucidum called, and what are some of its features?
Stratum granulosum
One or more layers of cells starting to die and become hard
Are in the process of keratinisation- becoming fibrous protein similar to that in hair and nails
What is the layer beneath the stratum granulosum called, and what are some of its features?
Stratum germinativum
Composed of several layers of living cells that are capable of cell division
Innermost layer of the epidermis, and contains melanin- pigment that gives colour to the skin
The more abundant the melanin, the darker the skin colour
Damage to this layer (e.g., burns) requires skin grafts
What are features of the dermis layer of the skin?
Beneath the epidermis and is composed of connective tissue
Contains the lymphatics, nerves, nerve endings, blood vessels, sebaceous and sweat glands, elastic fibres and hair follicles
What are the two layers of the dermis and what features do they have?
Papillary layer: arranged into microscopic structures that form ridges, these are the finger- and footprints
Reticular layer: beneath the papillary layer; white fibrous tissue that supports the blood vessels
What is another name for the subcutaneous tissue and what are some of the features?
Hypodermis
Composed of adipose and connective tissue. It supports, nourishes, insulates, and cushions the skin
The dermis is connected to underlying tissue by the subcutaneous tissue
How can the hair be described?
Threadlike structure formed by a group of cells that develop within a hair follicle or socket
Each hair has a shaft that is visible and a root that is embedded in the follicle
What is attached on the side of each hair follicle?
A pilomotor muscle
What is the importance of the pilomotor muscle?
Stimulated by skin irritants, emotional arousal, or cold temperatures, and reacts by contracting
What does the contraction of the pilomotor (and therefore the hair follicle) cause?
Goose flesh or goose pimples
What is the hair papilla?
At the base of each hair follicle- bulb enclosing a loop of capillaries
Why is the hair papilla significant?
Provides nourishment to the hair
One of the few living parts of the hair
Responsible for hair growth
What are the three parts of the hair?
The cuticle, the cortex and the medulla
Why is the cuticle of the hair significant?
The transparent cuticle covers the hair shaft like shingles on a roof, protecting it from the elements and chemicals, and from losing moisture
Why is the cortex of the hair significant?
The cortex provides most of the hair’s weight
It contains melanin which provides color to the hair, stores oils, provides flexibility and elasticity, and adds shape to the hair
Why is the medulla of the hair significant?
When the cuticle is damaged and exposes the cortex, hair looks dull and dry
The medulla is a inner hollow core that runs the length of the shaft
What are sebaceous glands and how can they be described?
They are oil glands
Each sebaceous gland secretes sebum, which lubricates the hair and skin
Amount of secretion varies with age, puberty and pregnancy
What are finger- and toe nails?
Hard keratin structures that protect the ends of fingers and toes
What is the nail root?
Also called the germinal matrix, or nailbed, begins several millimetres into the finger and extends to the edge of the white, crescent shaped lunula
Why is the nail root important?
This is where the growth occurs… approximately 1 mm per week
The under-surface of the nail plate or body of the nail has grooves that help anchor it
What is the cuticle of the nail also known as?
Eponychium
What is significant about the eponychium?
Fuses the nail plate and the skin of the finger together to form a waterproof barrier
Where is the hyponychium?
Underneath the free edge of the nail
What is the significance of the hyponychium?
It also creates a waterproof barrier, fusing the skin of the finger to the underside of the nail plate
Can a lost finger- or toe nail regenerate?
Yes
What are ingrown nails?
Those that have curled down or around and are growing into the skin
May become swollen or inflamed
Trim toenails straight across to avoid this growth pattern
What are sudoriferous glands?
Sweat glands
What is the approximate number of sudoriferous glands in the human body?
About 2 million are distributed over the surface of the body, more numerous on the palms of the hands, soles of the feet, forehead, and axillae or underarms
What are some factors that can impact skin health?
Water
Environment- clogging pores
Hygiene
Sun exposure
Genetics
Diet
Alcohol- dehydration
Lifestyle
Sleep
Stress
Inside out- healthy outside reflects a healthy inside
How can climate change affect skin health?
Increases likelihood of skin infections, dry skin and skin cancers
Increase in melanomas (skin cancer in the pigment cells)
What is significant about melanoma?
Goes many layers to the lymph nodes
Where does skin cancer begin?
Begins in the cells that make up the outer layer (epidermis) of skin
What is basal cell carcinoma and where does it manifest?
A type of skin cancer
Begins in basal cells, which make skin cells continuously push older cells towards the surface
Where can squamous cell carcinoma manifest?
New cells move upwards and can become flattened squamous cells
What is significant about eczema and psoraisis?
Hypersensitivity to substances like hand sanitisers and can cause skin to get dried out in winter
What are other conditions that can affect skin health?
Enterovirus infection
Tinea Pedis (athlete’s foot)
Bullous Impetigo (bacterial skin infection that causes the formation of blisters
