Human Anatomy Chapter 5 Flashcards
The integumentary system is composed of
Skin, hair, nails, sweat glands, sebaceous glands, mammary glands
Skin
Most visible organ of the body, helps protect from the environment, helps to regulate body temperature and excretes when necessary, helps synthesize and store lipids, and vitamin D3, helps coordinate immune response to pathogens and cancers, can sense information
Cutaneous membrane
Epidermis, dermis
Accessory structures
Hair follicles, exocrine glands, nails
Epidermis
Superficial epithelium
Dermis
Underlying connective tissue, deep is hypodermis, known as subcutaneous layer or superficial fascia, not part of integument
Accessory structures
Hair follicles, exocrine glands, sweat glands/sebaceous glands, nails
Function of Integumentary system
Physical protection, regulation of body temperature, excretion of products, synthesis of products, sensation, immune defense
Keratinocytes
Produce a tough protein called keratin
Melanocytes
Pigment cells located deep in the epidermis, produce melanin (skin color)
Merkel cells
Sensory cells
Langerhans cells
Wandering macrophages
Stratum basale
Consists of basal cells
Location of melanocyte: produce melanin (lack of melanin results in albinism)
Cells in the area are undergoing active reproduction
Skin surfaces that lack hair contain specialized cells known as Merkel cells
Deepest basal layer
Stratum Spinosum
Keratinocytes are bound together by desmosomes
Tonofibrils are associated with the desmosomes
Langerhans cells are most common in the superficial portion
Some keratinocytes divide in this layer
Stratum Granulosum
Keratinocytes produce lots of keratin and keratohyalin
Excess synthesis produces calluses
Keratin fibers develop as cells become thinner and flatter
Stratum Lucidum
Found in palms of hands and soles of the feet
Appears as a glassy layer in thick skin only
Stratum Corneum
Superficial layer
Consists of interlocking, dehydrated, dead cells
Allows slow water loss by insensible perspiration
Contains multiple layers of flattened, dead, interlocking keratinocytes
Thick skin
Found on palms and soles, made of five layers of cells
Thin skin
Found on the rest of the body
Made of four layers of cells, because the stratum lucidum is typically absent
Dermal ridges
Stratum germinativum forms dermal ridges
Ridges (dermal papillae) extend into the dermis
Creates ridges we call fingerprints
Skin color due to:
Dermal blood supply, thickness of stratum corneum, various concentrations of carotene and melanin (under genetic control)
Dermal blood supply
Reduction in blood flow results in a pale color
Sustained reduction in blood flow results in cyanosis
Carotene
Derived from carrots, corn, and squash
Can convert to vitamin A needed for synthesis of visual pigments in the photoreceptors of the eyes
Melanin
Produced and stored in melanosomes within melanocytes
Creates natural skin color and tan: protects the skin against UV radiation
Melanocyte
Exposure to UV light, increases the rate of melanin formation, tanning begins, repeated exposure to UV light: can be result in long-term epidermal and dermal damage, results in abnormal connective tissue structure, results in premature wrinkling, can result in epidermal skin cancer
Vitamin D formation
UV light converts a cholesterol-related precursor to vitamin D3 (cholecalciferol), vitamin D3 undergoes changes in the liver and kidneys to the active form of vitamin D (calcitriol)
Papillary layer
Superficial dermis
Loose connective tissue
Dermal papillae
Capillaries
Axons of neurons
Provides physical attachment to the epidermis
Reticular layer
Deep dermis
Consists of: interwoven network of dense irregular connective tissue, hair follicles, sweat glands, sebaceous glands
Wrinkles, stretch marks, and tension lines
Interwoven collagen fibers provide tensile strength, elastic fibers allow the skin to stretch and recoil, skin wrinkles are due to : age, change in hormone levels, UV light
Extensive stretching during pregnancy (or excessive weight gain) can cause reticular fibers to break
The skin does not recoil
Wrinkles and creases, resulting in stretch marks
Tension lines
Collagen and elastic fibers have a tendency to organize themselves in a parallel pattern
In certain areas of the body, there is a pattern of cleavage lines due to stress or a specific type of movement
To reduce scar formation (extensive damage to the fibers), surgeons try to cut parallel to the lines of cleavage
Blood supply to the skin
Arteries and veins form the cutaneous plexus
Smaller blood vessels form the subpapillary plexus
Function: thermoregulation, blood flow to the skin is regulated to help maintain constant flow to other tissues of the body
Nerve supply to the skin
Function: control blood flow to the skin, adjusts gland secretion rates, monitors sensory receptors
Examples: Tactile discs (light touch receptors), Ruffini corpuscles (stretch receptors), Lamellated corpuscles (deep pressure and vibration receptors)
Subcutaneous Layer
Is deep to the dermis also called hypodermis and superficial fascia, not technically apart of the integument, helps to stabilize the integument
Consists of: adipose tissue, major blood vessels
Hypodermic needles, subcutaneous injections
Accessory structures
Includes: hair follicles, sebaceous glands, sweat glands, nails
Hair follicles and hair found everywhere but:
Palms, soles of feet, sides of the fingers and toes, lips, glans penis, clitoris, labia minora, inner surface of labia majora
Hair production
Hair consists of: hair papilla, hair bulb, hair matrix: keratinized - medulla, cortex, cuticle- hair root, hair shaft
Medulla
Consists of soft keratin
Cortex
Consists of hard keratin
Hair root
Anchors the hair to the skin
Hair shaft
Extends from the skin surface
Functions of hair
Protection from UV light, insulation, guards entrance to nose and ears, movement of the hair sends impulses via nerves to the brain (presence of root hair plexus), contraction of the arrector pili muscle (goose bumps)
Types of hair
Langugo, vellus, terminal
Languno
Unpigmented hair that develops after three months of embryonic development
Vellus
Covers most of the body
Terminal
Covers the head, comprises the eyebrows, comprises the eyelashes
Hair color due to:
Variation in melanin production by the melanocytes: more melanin creates darker hair, decreased production results in gray hair, lack of melanin and the presence of air bubbles in the hair shaft results in white hair
Hair color influenced by:
Genetics, hormones, environmental factors
Growth and replacement of hair
Each hair follicle goes through a hair growth cycle, active stage: hair grows about 0.33 millimeters per day, lasts for 2 to 5 years, resting stage: hair loses its attachment to the follicle, hair becomes a club hair
Club hair is lost and replacement hair is produced
Male pattern baldness: due to changes in sex hormones
Nails
Function: provide protection for the tips of the fingers and toes
Structure: nail body - covers the nail bed, nail root - deep in the dermis near the bone, lateral edges of the nail forms the lateral nail groove and lateral nail folds, eponychium/hyponychium/lungula/free edge/proximal nail fold
Aging
Epidermis becomes thinner, dermis thinner, number of langerhans cells decreases, vitamin D declines, melanocyte declines, glandular declines hair follicles stop functioning, skin repair slows dowm, blood supply to dermis decreases, hair and body fat distribution fades (hormones decrease)
