LO 4 Flashcards
______ is anatomically simple but functionally important sheet like structures called membranes
Skin
______ is another name for the skin and the connective tissue underneath
Integument
_________ is the integument when considered as a body system
Integumentary system
Hair, nails, and skin glands are examples of _________
Skin appendages
Describe membranes
- Thin, sheet-like structure found throughout the body
- Covers and protect internal and external surfaces and organs
- Anchors organs and bones
- Secrete lubricating fluids to reduce friction
What are the 2 major types of membranes in the body?
- Epithelial membranes (2 distinct layers - epithelial tissue and underlying layer of connective tissue)
- Connective tissue membranes - composed largely of various types of connective tissue
What are the 3 types of epithelial membranes?
- Cutaneous membrane - the skin
- Serous membrane - parietal + visceral
- Mucous membrane
Describe the cutaneous membrane (the skin)
- Primary organ of the integumentary system
- Largest and and one of the most visible organs - 16% of body weight
- Made up of superficial layer of epithelial cells + underlying layer of supportive tissue
Describe the serous membrane
- Made of 2 layers:
i. Epithelial layer: thin layer of simple squamous epithelium ii. Connective tissue layer: very thin, glue-like basement membrane (holds and supports the epithelial cells)
Also secretes lubricating fluid to decrease friction
What are the 2 types of serous membrane?
- Parietal - lines the walls of body cavities (e.g. peritoneum in thoracic cavity)
- Visceral - covers organs in body cavities (e.g. visceral pleura on lungs)
Serous membranes can be easily visualized with this analogy
- Fist pushing into a water balloon
- Demonstrates how serious membranes form a double-walled structure containing a thin pocket of fluid (e.g. heart is surrounded by serous paracardium)
Describe 2 serous membrane diseases
- Pleaurisy - inflammation of the serous membranes that line the chest cavity and cover the lungs (i.e. the pleura)
- Peritonitis - inflammation of the serous membranes that line the walls of the abdominal cavity and cover the abdominal organs (i.e. the peritoneum)
Describe mucous membranes
- Line surfaces the open directly to exterior of body (lining of respiratory, digestive, urinary, and reproductive tracts)
- Epithelial portion varies depending on location and function
- Epithelial cells produce mucous to keep the membranes soft and moist
________ is the transitional area where the skin and mucous membranes meet
Mucocutaneous junction (eyelids, nostrils, anus)
Describe connective tissue membranes
- Do not contain epithelial components
- Produce lubricant called synovial fluid
- Examples are synovial membranes between joints and the lining of the bursae (cushion-like sacks found between many moving body parts)
What are the 2 primary layers of the skin?
- Epidermis
- Dermis
Describe the supporting layer of the skin (hypodermis)
- Loose connective tissue
- Fat - insulation from extreme heat, alternative source of energy, protective cushion
Describe the epidermis
- Outer most layer of skin
- Relatively thin sheet of stratified squamous epithelium
- Arranged in up to 5 distinct layers
Describe the stratum germintativum (also called stratum basal or basal layer)
- Is the inner-most layer of the epidermis
- Continuously undergoes mitosis
- New cells are pushed upward through additional layers “strata” of cells - as they approach surface, cells die and their cytoplasm is replaced by keratin
Describe keratin
Tough, water-proof material that provides cells in the outer layer of the skin with an abrasion resistant and protective quality
______ is the outermost layer of the epidermis, also known as the horny layer
Stratum corneum
What are the 5 layers of the epidermis from the outermost down?
- Stratum corneum (horney layer) - thick, dead, keratin-filled cells (layer that sheds)
- Stratum lucidum - only present in thick, hairless skin (e.g. palms)
- Stratum granulosum - where cell first becomes full of keratin
- Stratum spinosum
- Stratum germintativum (stratum basal) - epithelial cells constantly dividing
______ produce melanin and are stimulated by the sun
Melanocytes
We have a totally new epidermis every _________
24-45 days
Describe skin pigment
- Gives skin colour
- Produced in stratum germintativum by melanocytes
- Pigment is called melanin (brown/dark) - primary function to absorb harmful UV radiation from sunlight
Describe the dermal - epidermal junction
- Specialized area between epidermis and dermis
- Like glue holding the two layers together
- Blisters caused by breakdown of this junction
Describe the dermis
- Deeper and thicker than epidermis
- Composed largely of connective tissue
- Cells scattered further apart than epidermis and there are many fibres (collagen and elastic) between cells
What does the dermis contain?
- Nerve endings
- Muscle fibres
- Hair follicles
Sweat and sebaceous glands - Blood vessels
What are the 2 distinct layers of the dermis?
- Papillary layer (superficial layer) - parallel rows of dermal papillae, helps bind dermis to epidermis, basis of fingerprinting, improves our grip
- Reticular layer (deepest layer) - network of collagenous & stretchable fibres, number of elastic fibres decreases with age (wrinkles)
Describe the hypodermis (subcutaneous tissue)
- It is NOT a part or layer of the skin 🚫
- Lies deeply into the dermis
- Forms a connection between the skin and underlying structures (muscle and bone )
________ is the process of inserting a hollow tube into the subcutaneous tissue (hypodermis) and removing fat with a vacuum aspirator
Liposuction
What do you need to understand about hair?
- Human body covered in millions of hairs
- At the time of birth, most of the follicles required for hair growth are present
- Hairless areas include lips, palms, soles of feet
________ is the hair of newborns, means down in Latin, and is soon replaced with stronger and more pigmented hair
Lanugo
Describe hair growth
- Requires an epidermal tube-like structure called a hair follicle (developed by epidermal cells growing down into the dermal layer)
- Growth begins from small cap-shaped clusters of cells at the base of the follicles called hair papilla
- Hair root lies inside the follicle
The visible part of the hair is called the _______, and most hair is _______
Shaft; invisible
_________ is specialized smooth muscle attached to the base of dermal papillae and contract to cause goosebumps/ hair standing on ends
Arrector pili
What do you need to understand about skin receptors?
- They are specialized nerve endings that make it possible for skin to act as a sense organ
- They relay messaged to the brain of touch, pain, temp, and pressure
________ skin receptors detect light touch (generally superficial)
Meissner’s (tactile) corpuscles
_______ skin receptors detect pressure (generally deeper)
Pacini (lamellar) corpuscles
_________ skin receptors detect low frequency vibration and fine touch
Krause end bulbs (bulboid corpuscles)
_______ nerve endings detect pain
Free
What do you need to understand about nails?
- Produced by epidermal cells over ends of fingers and toes (when cells fill with keratin)
- Visible part called nail body
- Root lies in. Groove and is hidden by cuticle
- Crescent shaped area near root is called lunula
- Nail bed can change colour with blood flow
The ______ is the crescent shaped area near the root of the nail
Lunula
Skin/cutaneous glands (all exocrine) can be divided into _______ and _______
- Sudoriferous glands (sweat)
- Sebaceous glands (oil)
Sudoriferous glands (sweat) can be divided into ________ and _______
- Eccrine
- Apocrine
Describe eccrine glands
- Function throughout life
- Most numerous, important, and widespread sweat glands
- Produce sweat, which is eliminated through pores
- Assist in body heat regulation
Describe apocrine glands
- Enlarge at onset of puberty
- Mostly in armpit and around genitals
- Secretion is thicker/milky
- Odor is caused by bacterial breakdown
Describe sebaceous glands
- Grow where hair grows
- Secrete oil (sebum) for hair and skin (ducts open into hair follicles
- Level of secretion increases in adolescence
- Amount of secretion regulated by sex hormones
- Sebum in sebaceous gland duct may darken into blackhead
- Secretion decreases with age
What causes skin cancer?
Causes may be genetic and/or environmental (e.g. sun exposure)
What are the 3 most common types of skin cancer?
- Squamous cell carcinoma
- Basal cell carcinoma
- Malignant melanoma
Describe squamous cell carcinoma
- Slow growing
- Malignant tumor of epidermis
- First appear as hard, raised nodules
- If left untreated, it will grow and metastasize
Describe Basal cell carcinoma
- Most common type of skin cancer
- Usually on upper face
- Least likely to metastasize
- Small raised lesion
- Erodes in the centre, forming a bleeding, crusted crater
Describe malignant melanoma
- Most serious form of skin cancer
- Can develop from a benign pigmented mole
- Develops into a dark, spreading, cancerous lesion
- Risk is significantly higher if you have 2 blistering sunburns before 20
What are the warning signs of malignant melanoma (A, B, C, D, E)
- Asymmetry (one side bigger than other)
- Border (irregular)
- Colour (uneven)
- Diameter (>6mm)
- Evolving
What are the 5 most important functions of skin?
- Protection
- Temperature regulation
- Sensation
- Excretion
- Synthesis of vitamin D
What are the steps of skin repair?
- Blood clots, quickly stopping blood loss
- Germintativum cells grow laterally to close gap and restore epidermis
- Fiber-producing cells in dermis repair damaged network of fibers
- Clot dissolves, leaving repaired epidermis and thickened dermis
________ and _______ are important contributors to the skin being the body’s first line of defense
- Keratin (horny layer) - infections by microbes, harmful chemicals, cuts and tears, excessive fluid loss
- Melanin - UV rays
The skin’s mechanisms of temperature regulation involve ______ which has a cooling effect
Heat loss through evaporation
How does the body cool?
- Regulation of sweat secretion - heat loss through evaporation
- Regulation of blood flow near skin’s surface - head loss through radiation
Describe the skin’s role as a sense organ
Receptors serve as receivers for the body, keeping it informed of changes in the environment (e.g. touch, pressure, 🔥, ❄️)
The body can lose substances through the skin via sweat. For example ____, _____, and _____
- Salts
- Waste products
- Hormones
Describe the skin’s role in vitamin D synthesis
- Initiated when sun exposed to UV
- Series of reactions involving the liver, kidneys resulting in the active form of vitamin D
- Most North Americans are deficient
______ is one of the most serious and frequent problems affecting the skin
- Burns
Causes of burns include _____
- Sun
- Chemicals/ acids
- Electricity
- Friction
The treatment and recovery or survival of burns depends on _____
- Total area involved
- Severity or depth of burns
(Rule of nines in adults - surface area estimation)
What is the rule of nines?
- Estimates the percent of body burned
- Body surface area divided into 11 areas of 9% each
- Additional 1% at genitals
- Intended for rapid assessment
Describe first degree (superficial partial-thickness) burns
- Involves only the surface layer of epidermis
- Minimal damage (e.g. peeling and blistering)
Describe second degree (partial-thickness) burns
- Involve the deep epidermal layers
- Always cause injury to upper layers of dermis
- Severe pain, swelling, blisters, scarring
Describe third degree (full-thickness) burns
- Complete destruction of the epidermis and dermis
- May involve underlying muscle and bone
- No pain initially; intense pain follows
- Serious fluid loss and increased risk of infection
Describe fourth degree (full-thickness) burns
- Muscle and bone involved
- May require extensive grafting (or amputation)
- High voltage electrical burns
- Exposure to extreme heat
