Lecture 15 - Integumentary System Flashcards
What is integumentary system made up of
The skin
- organ and epithelial membrane
Accessory organs
- sweat and sebaceous glands, hairs, nails
What are 6 primary functions of the integumentary system
- Regulation of body temperature
- Protection of the body from the environment
- Senses
- Excretion
- Certain specialized cells for the immune sys
- Synthesis of the vitamin D precursors
How does integumentary system regulate body temp
Maintains it through evaporation
- increases and decreases in blood flow
How does integumentary system provide protection for the body from the environment
Physical barrier to prevent things from getting in - multiple layers of dead cells Protection from UV Ray's - melanin Protection from Microorganisms - thin surface film on skin traps them
How does integumentary system use senses
Touch - Meissner's corpuscles are the tough sensors Temperature - thermoreceptors Pressure - pacinian receptors Pain - Nociceptors
What is excreted by integumentary system (5)
- H2O
- Salts
- Urea
- Ammonia
- Uric acid
What certain specialized cells for immune system are in the skin
Macrophages
Dendritic cells
What is the importance of skin synthesis of the vitamin D precursors
Essential for the absorption of Ca2+ (calcium)
- for bone growth
What are the 2 distinct parts of the skin
- Epidermis
2. Dermis
How are epidermis and dermis linked to hypodermis
Through a functional interaction as hypodermis is the underlying layer
- hypodermis not considered part of skin proper
What is the superficial layer of the skin
Epidermis
What is tissue origin of epidermis
Ectoderm
Structure of epidermis
- no blood vessels or neural fibers
- stratified squamous epithelium
What are 4 types cells that make up epidermis
- Keratinocytes
- Melanocytes
- Dendritic cells
- Tactile cells
What is most abundant type of cell in epidermis
Keratinocytes 90% of epidermal cells
What do keratinocytes produce
Keratin that is impermeable
How are keratinocytes joined
Desmosomes
What do melanocytes produce
Pigment that is transferred into the keratinocytes
What does accumulation of melanocytes do
Protects the keratinocytes DNA from the harmful effects of UV rays
- helps prevent melanoma (cancer)
What is another name for epidermal dendritic cells
Langerhan’s cells
What is function of dendritic cells and where do they originate from
Originate from bone marrow
Contribute to the activation of cells from the immune system
- a type of antigen presenting cell (APC)
What’s another name for Tactile cells
Merkel
What to Tactile cells form
Tactile corpuscles / Merkel discs
What happens when tactile corpuscles come in contact with sensory neurons
They play a role with touch which is the most sensitive
What does strata mean
Layers of epidermis
How many layers make thick skin
5
How many layers make thin skin
4
What does 5th layer mean
Cannot grow hair
- extra layer is stratum lucidum
What are 4 layers of strata in order of most superficial to most deep
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
Describe stratum corneum
- cells are dead
- Represented by flat membranous sacs filled with keratin.
- glycolipids in extracellular space.
Describe stratum granulosum
- cells are flattened
- organelles deteriorating
- cytoplasm full of lamellated granules (release lipids) and keratohyaline granules
Describe stratum spinosum
Cells contain thick bundles of intermediate filaments made of pre keratin
Describe stratum basale
Cells are actively mitotic stem cells
- some newly formed cells become part of the more superficial layers
Structure of basal layer (stratum basale or germinativum)
- 1 row of columnar cells that rapidly divide
- Principal layer of epidermis
- attached firmly to underlying dermis with wavy borderline
Structure of prickly layer ( stratum spinosum)
- 8 - 10 rows of cells connected by desmosomes
- keratinocytes absorb the pigment of melanin from the melanocytes by phagocytosis
- Langerhan’s (dendritic) cells are distributed amongst the keratinocytes
Structure granular layer (stratum granulosum)
- 3-5 rows of cells that produce granules of:
a) keratohyalin - this favors the accumulation of keratin in the upper layers
b) glycophospholipids - connected by tight junctions (forms barrier)
Structure of clear layer (stratum lucidum)
- 3-5 rows of clear, dead keratinocytes filled with a eleidin (protein)
- only in the thick skin
Structure of horny layer (stratum corneum)
- 20-30 rows of dead cells filled with keratin, keratinized or cornified cells
- cornu = horn
- protection against abrasions
What happens to dead cells on horny layer
They fall away and are replaced by the underlying layers
What stimulates cell renewal
Epidermal growth factor
What happens when there is repeated abraision to stratum corneum
There is increased mitotic activity by stratum basale which forms things like calluses
What is contained in dermis ( 7)
- Elastic fibers
- Collagen fibers
- scattered cells: fibroblasts, adipocytes, macrophages
- Nerve fibers
- Vascular supply
- Sweat and sebaceous glands
- Hair follicles
What are 2 layers of dermis
Papillary layer
Reticular layer
Structure of papillary layer
About 20% of the dermis
Loose CT containing thin elastic fibers
Contains projections called dermal papillae
How does epidermis connect to dermis
With epidermal ridges interlocking to dermal papillae
Special feature of papillae
Causes ripples at the surface of the epidermis because of presence of sweat glands
- how you get fingerprints
- enhance gripping ability of hands and feet
Structure of reticular layer
About 80% of dermis
Made up of dense irregular CT having bundles of collagen and elastic fibers
•have tension lines (lines of cleavage or of langer)
- bundles are oriented in parallel lines (like fingers) and circular pattern (ex. Heart area )
Structure of hypodermis
- sub cutaneous layer or superficial fascia (sheath)
- attached skin to underlying organs
- loose fibrous CT
- rich in adipocytes
What 3 pigments make up skin color
- Hemoglobin
- Melanin
- Carotene
What is carotene
A yellow to orange pigment that comes from plants
- it is accumulated in horny layer of epidermis
- stored in adipocytes
What would give skin a reddish tone
Hemoglobin rich in oxygen
What would give skin bluish color
Unoxygenated blood cyanosis
What gives skin jaundice yellow cast
Hepatic problems
High bile/ bilirubin
What makes different skin colour
- people of diff races all have same # of melanocytes but:
1. They produce diff quantities of melanin
2. There are melanins of diff hues - Gene’s dictate rate and type of melanin produced
What are the Eccrine sweat glands
Coiled and tubular gland
- excretes sweat which is composed of:
Water, salts, ammonia, uric acid and urea
- a way for body to release excess heat by evaporation
Where are most eccrine sweat glands
They are the most abundant of the skin appendages
- palm, sole of foot, forehead
Where is apocrine sweat gland located
In Dermis
- armpit, areola of breast, around the anus
-secretes in the hair follicle (apical surface detaches)
Description of sweat
- more viscous (lipids & proteins)
- odorless but not via bacterial degradation
- stimulated during stress or sexual arousal
- under the influence of androgens
Where and what are ceruminous glands
Modified apocrine sweat glands in external ear canal
- they secrete cerulean (earwax)
- there function is to block or trap foreign bodies
What and where are mammary glands
Modified apocrine sweat glands in the breast
- produce and secretes milk
What are sebaceous glands
- not present in thick epidermis
- secrete sebum (fats, cholesterol, proteins, salts)
- they lubricate hair and skin and have antifungal properties
2 main parts of hair
Shaft (part of hair that emerges from epidermis)
Root ( part embedded in epidermis, dermis and sometimes hypodermis) - surrounded by hair follicle
What are the 3 concentric layers of keratinized cells in hair
Medulla
Cortex
Cuticle
Lanugo
Down hair on newborn and fetus that falls off after birth
How much do we shed hair on average
90 per day
What impacts hair shedding
- Stress (fever)
- Surgery
- Serious emotional shock
- Medication (anticancer chemotherapy)
- Diet poor in protein
- Lactation
What can cause irreversible hair shedding
- Trauma is prolonged
- Excessive radiation
- Additional genetic factors
What are nails made of
Layers of dead and dense epidermal cells and filled with keratin
- hard and transparent
What are the parts of nails
- Root
- Lunule
- Body
- Cuticle
- Nail bed
Two rules to calculate extent of burns
Rule of nines
Rule of palms
What % is head and neck
A and p 9%
What % is upper limbs
A and p 18%
What is % trunk
A and p 36 %
What is % perineum
1%
What is % lower limbs
A and p 36 %
What is a 1st degree burn
- superficial burn
- only epidermis affected
- redness, swelling, pain
- heals 2 -3 days
What is 2nd degree burn
- superficial burn
- epidermis and superficial layer of dermis
- symptoms of 1st degree + blisters
- heals in 3-4 weeks
- can leave scars
What is 3rd degree burn
- deep burn
- all of the thickness of skin
- no pain (nerve endings destroyed)
- risk of infection (very high)
- skin grafting usually needed
What is cancer
- abnormal mass of cells that multiply uncontrollably
- invasive and can propagate
What is malignant tumor
- cancerous
- spreads to other parts of body (metastasize)
What are risk factors of cancer
- excessive exposure to UV Ray’s
- repeated irritation due to infections, chemical products, wounds
What is basal cell carcinoma
- in stratum basale
- invades dermis and hypodermis
- metastasize seldomly
- surgical excision is full cure
What is squamous cell carcinoma
- cancer of keratinocytes of stratum spinosum
- scaly, red papules
- metastasize if not removed
What is melanoma
- cancer of melanocytes
- highly metastatic
- resistant to chemotherapy
What is ABCD rule to recognizing melanoma
Asymmetry (2 sides of pigmented spot do not match)
Border irregularity (indentation)
Colour (pigmented spots: black, brown, tan, blue, red )
Diameter (>6mm in diameter )
