A&P 1: Block 2 Flashcards
Accessory structures of the skin
hair nails glands muscles nerves
Where does the hypodermis layer fall into the layers of skin?
Sub-Q layer consisting of areolar and adipose tissue
Not a part of the skin
7 specific functions of the skin
Thermoregulation Protection Sensation Excretion Synth of Vitamin D Blood reservoir Absorption
Epidermis is composed of what type of epithelium?
Keratinized stratified squamous epithelium
What are the 4 types of cells within the epidermis?
Keratinocytes
Melanocytes
Langerhans
Merkel
90% of the epidermal cells are ____
keratinocytes
How/when are keratinocytes formed?
When new cells from mitosis fill with keratin
Major functions of keratin
Tough, fibrous protein that is
waterproof
protects (heat, microbes, chemicals)
UV protection
What part of the cell makes melanin?
Organelle melanosome within melanocytes
Melanin is brown-black pigment that contributes to skin color and absorbs UV light
After melanin is made by melanocytes, where is it transferred to? How does it get transferred?
Melanocyte projections extend between keratinocytes and pass melanin granules to them
Melanin granules cluster over nucleus on skin surface side, shields DNA from UV light
What is melanin synthesized from?
AA tyrosine w/ tyrosinase enzyme
Function of Langerhans cells?
What type of cell are they?
Immune response to microbes that invade the skin
Immune, dendritic
Where are Merkel cells found?
What is their function?
Deepest layer of epidermis (Stratum Basale)
Contact w/ tactile discs (Merkel discs), a type of sensory neuron
What two structures make up the sensation of touch?
Merkel cells
tactile discs
What are the layers of skin
Corneum Lucidum Granulosum Spinosum Basale
Lucidum- only present on surface areas of a lot of friction (finger tips, soles)
Characteristics of the Stratum Basale
Deepest layer of epidermis
Mostly keratinocytes, few melanocytes and Merkel cells
What are the intermediate filaments of keratinocytes and where is it found?
Tonofilaments
Intermediate filament of keratinocytes in the Stratum Basale
Contains pre-cursor protein for keratin synthesis
Characteristics of Stratum Spinosum
8-10 layers of keratinocytes, few Langerhans
Cells still alive at this layer, some are dividing
Older cells start to flatten here
Characteristics of Stratum Granulosum
3-5 layers of flattened keratinocytes
Transition marker for deeper living/superficial dead cells
Filled w/ keratin granules
Waterproofing lipids from lamellar granules are here
Characteristics of Stratum Lucidum
Only on fingertips, soles, palms
3 layers of flat, dead keratinocytes filled with keratin
Characteristics of Stratum Corneum
Most superficial
25-30 layers of flat, dead cells
Cell interior mostly keratin
Lipids from lamellar granules form waterproof layer here
What type of tissues make up the dermis
Irregular CT of collagen and elastic CTs
What structures are found in the dermis
vessels nerves glands (oil and sweat) Hair follicles arrectores pilorum
What are the two regions of the dermis?
Papillary- superficial
Reticular- deeper
Characteristics of the Papillary region of the Dermis
Just deep to stratum basale
Increases surface area for diffusion, better adhesion to epidermis
What receptors are present in the Papillary region of the Dermis
Touch corpuscles- Meissner- touch/light touch
Free nerve endings- no structural specialization- warm, cold, pain, tickle
Characteristics of the Reticular Region of the Dermis
Dense irregular CT w/ collagen and elastic
Gives skin it’s strength and elasticity
Spaces between fibers filled with adipose, follicles, nerves, oil and sweat glands
What layer of the skin provides the skin strength, extensibility and elasticity?
Reticular region
Collagen and elastic fibers
Subcutaneous layer is made of what tissues?
Areolar and adipose
What structures are found in the subcutaneous layer?
Fat
Fibers attaching dermis to deeper tissues
Larger vessels
Sensory receptors: Pacinian/lamellated corpuscles- pressure
Epidermal ridges aka
fingerprints
When do epidermal ridges form in development/
3 and 4th month of fetal development
Contours of underlying papillary region
Forms lines, loops and whorls
Where do sweat glands open to on fingertips?
Epidermal ridges
Skin color is a combination of what things?
Which ones are genetically determine?
melanin
carotene
hemoglobin
Amount/expression of melanin and carotene- genetically determined
What does melanin provide to skin?
What does increased sun exposure do to these cells?
Amount causes skin color
Increased exposure= increased enzymatic activity of malanosomes, increased melanin production
What does Carotene provide to skin?
yellow-orange pigment
Pre-cursor for Vitamin A
What does Hemoglobin provide to skin color?
O2 carrying pigment in RBCs
When Melanin or Carotene are low, epidermis appears translucent
Causes skin to appear pink
What are the parts of the skin’s hair shaft and root?
Medulla
Cortex
Cuticle
What are skin hairs composed of?
Dead, keratinized cells bonded by proteins
How do skin hairs grow?
Cell division at base of follicle via mitosis in the hair matrix
What is the canal called that skin hairs grow through?
Pilary canal
What is the hair bulb made of?
Germinal layer of cells called matrix
Site of cell division that produces the hair
What layer does the hair bulb come from?
Stratum basale
What are the ancillary structures of hair?
Sebaceous gland
Smooth muscles
Root plexus
What type of cells surround the root hair plexus?
Dendrites
Nerve endings
Generates nerve impulses if hair shaft is moved
Shaft acts like a fulcrum
Sensitive to touch and movement
What are the 3 parts of a nail?
Body- visible (lunula- white part of proximal nail)
Free edge
Root- epithelium deep is the nail matrix, mitotic division= growth
What are nails made of?
Keratinized epidermal cells
When nails grow, new cells push old ones forward along what basale?
Stratum
3 functions of sebum?
Prevents drying out
Prevents evaporation
Inhibits bacterial growth
What are the two types of sweat glands?
Eccrine- (merocrine) found on most of skin, thermoregulation
Apocrine- hair that develops at puberty (axilla, groin, beard)
Define psoriasis
Where is it commonly found?
keratinocyte division and movement more rapidly than stratum basale/corneum and shed prematurely
Knees, elbows, scalp
Virtually all skin cancers are attributed to excessive ___
sun
What are the 3 common forms of skin cancer?
Basal cell carcinomas- most common
Squamous carcinoma
Malignant melanomas (least common, most life-threatening)
Define albinism
inability to produce melanin
melanocytes unable to synthesize tyrosinase
Define vitiligo
Partial/complete loss of melanocytes from patches of skin (irregular white spots)
May be autoimmune
Under lying causes of erythema
redness of skin
injury heat infection inflammation allergies
Define striae
stretch marks
scars from dermis tearing
Define alopecia
What are its causes
lack of hair (partial or complete) aging endocrine disorder chemotherapy skin disease
Define contact dermatitis
inflammation of skin (redness, itching, swelling)
Caused by exposure of skin to chemicals= allergic reaction
What are the two types of wound healing
Epidermal- superficial, only epidermis involved
Deep wound- injury extends to dermis and subcutaneous layer (loss of some function and scar tissue)
What are the 4 overall steps of Deep Wound Healing?
Inflammatory
Migratory
Proliferative
Maturation
Characteristics of 1st degree burn
Only epidermis
Skin functions remain intact
3-6 day heal time
Sunburn
Characteristics of 2nd degree burn
Partial damage to epidermis and dermis
Some skin function lost (blisters)
3-4 wks heal time w/ scarring possibility
Characteristics of 3rd degree burn
Epidermis and dermis involvement
Skin function lost
AKA full thickness
Rule of 9s
Only for 2nd and 3rd degree burns on adults
Define abrasion
skin has been scraped away
Define Athletes foot
superficial fungal infection of skin on foot
Define blister
serous fluid with epidermis or between epidermis and dermis
Define callus
area of hardened/thickened skin
Define eczema
inflammation of skin characterized by patches of blister/dry/itch skin
Define wart
mass of uncontrolled growth of epithelial cells caused by papillomavrius
Define hirsutism
condition of excessive body hair
Define laguno
fine,non-pigmented hairs that cover body of fetus
Define Terminal Hairs
Secondary characteristic
Coarse, heavily pigmented
Head, eyebrows, eyelashes
Define Vellus hairs
fine/pale body hairs that develop during childhood
What does cartilage consist of?
Collage (strength) and elastic fibers embedded in chondroitin sulfate (resilience)
What are mature cartilage cells called? What space do they occupy?
Chondrocytes= mature
Derived from chondroblasts
Reside in lacunae (little lakes)
Most cartilage is covered in irregular CT called ____.
What developmental shift occurs to this tissue?
perichondrium
Becomes vascularized, becomes periosteum
Cartilage has no nerves except for where?
Perichondrium
Why does perichondrium cartilage heal slowly?
lack of intrinsic blood supply and confinement of chondrocytes to lacunae
What are the 3 types of cartilage
Hyaline- most abundant
Fibrinocartilage
Elastic
Where is Hyaline cartilage located?
Most abundant
End of long bones
Ribs, nose, trachea, bronchi and larynx
Provides smooth surface for movement to occur
Characteristics of fibrinocartilage and where is it located
thick bundles of collagen (very tough/strong)
Found as disc shaped segment between bones
Characteristics and location of elastic cartilage
Chondrocytes located in threadlike network of elastic fibers
External ear and epiglottis
Different functions of red and yellow bone marrow
Red- RBC formation
Yellow- triglyceride storage (adipose connective tissue)
Define diaphysis
Define epiphyses
Define metaphyses
Di- shaft, body of bone
Epi- distal/proximal portion of bone
Meta- connects Di and Epi
Where is the epiphyseal plate located?
at metaphyses of growth plate
Define articular cartilage
hyaline cartilage covering epiphyses
Define periosteum
dense irregular CT that covers bone, EXCEPT articular cartilage
Define endosteum
membrane lining marrow cavity
Histology break down of bone matrix
don’t know %s
25% water
25% collagen
50% hydroxyapatite- (calcium phosphate, calcium carbonate) for hardness/compression strength
What are the 4 cells found in bones
All derive from mesenchyme*
mesenchyme- 1st
Osteogenic- stem cells differentiate->osteoblasts
Osteoblasts- secrete bone matrix and become osteocytes
Osteocytes- mature bone cell, regulate bone matrix composition
Osteoclasts- release enzymes for digesting/remodeling bone
Regions of bones can by subcategorized into what 2?
Compact- cortical
Spongy- cancellous, trabecular
Compact bones contain units called?
Osteons- Harversian systems formed from concentric lamellae (rings of calcified matrix)
Interstitial lamellae- between osteons, left over fragments of older osteons
Where are the outer/inner circumferential lamelle located?
Outer- encircles bone beneath periosteum
Inner- encircles medullary cavity
Define lacunae
What connects these?
small spaces between lamellae which house the osteocytes
Connected by Canaliculi- channels w/ ECF
Where are blood and lymph vessels found within bone tissue?
Central canal
Define perforating (Volkmann’s) canals
allows transit of blood/lymph vessels to the outer cortex of bone
Spongy bone lacks ____
What replaces them?
Osteons
Lamellae arranged in lattice of thin columns called Trabeculae
Function of Trabeculae?
Spongy bones- support and protect red marrow, helps bones resist stress w/out breaking
Define hematopoiesis and where does it take place
blood cell production
Spongy bone
Within each trabecula of spongy bones there are what sub-structures?
Lacunae- osteocyte containing area for bone nourishment via blood circulating through trabeculae
What is the name of the process of forming new bones?
Ossification or,
Osteogenesis
What are the 4 situations that bone formation occurs?
Embryo development
Adulthood
Remodeling
Fx repair
What are the two different methods of osteogenesis?
Intra-Membrane ossification- (simpler) spongy bone production (can be remodeled into compact)
Endochondral ossification- process where cartilage is replaced by bone (forms both spongy and compact)
Give examples of Intra-membranous ossification process
Skull, mandible, clavicle
mesenchyme->develop w/in membrane->NO cartilage stage
Many ossification centers
Give examples of Endochondral ossification process
Most bones, especially long bones
Replacement of cartilage by bone
One primary and 2 secondary centers of growth
What are the two processes of bone remodeling?
resorption
deposition
Define acromegaly
bones are too thick and heavy
Too much new tissue
Bones can become too soft such as what 2 diseases?
Rickets
Osteomalacia
Steps/process of bone Fx healing
1: 6-8hrs after injury, formation of Fx hematoma from vessels breaking in periosteum and osteons
2/3: formation of callus (wks-6mon), phagocytes remove debris, fibroblasts deposit collagen to form fibrocartilaginous callus
Osteoblasts form bony callus of spongy bone
4: remodeling (several months) spongy replaced by compact, Fx line disappears, evidence remains
Function of Vitamin A in growth/remodeling
stimulates osteoblasts activity
Function of Vitamin C in growth/remodeling
Collagen synthesis
Function of Vitamin D in growth/remodeling
Ca absorption in GI tract
Function of Vitamin K/B12 in growth/remodeling
Bone protein synthesis
Importance of Ca homeostasis and where is it stored
Synaptic transmission, muscle contraction, blood clotting
99% stored in bones
Function of parathyroid hormone and bone structure
PH promotes resorption of bone matrix
prevents loss of Ca in urine
Promotes Vitamin D formation
Name of Vitamin D and it’s main function
Calcitriol- promotes Ca absorption in intestines
What is the production site and function of Calcithonin
Produced in parafollicular cells of thyroid gland
Lowers blood Ca levels by inhibiting reabsorption
What are the two main ways Ca blood can be increased?
Release of Ca from bone matrix
Retention of Ca in kidneys
Definition of joints
point of contact between two bones, bone and cartilage, or between bone and tooth
Define suture joint
thin layer of fibrous CT
Define syndesmoses
more space than suture, more fibrous CT
Epiphyseal plate
Define gomphoses
teeth in sockets of upper/lower jaw
What are the components of cartilaginous joints?
Fibrocartilage/hyaline cartilage
No synovial cavity
Little/no movement
What are the two types of Cartilaginous joints
synchondroses- primary cartilaginous join; hyaline cartilage connecting bones (may ossify w/ age)
symphyses- secondary cartilaginous; fibrocartilage
Characteristics of synovial joints
most moveable
Articular capsule- dense ir/regular
Synovial mem- secretes fluid
May contain articular discs (menisci)
List the 4 characteristics of Muscular tissue
irritable
contractable
extensible
elastic
What is a single muscle fiber called?
What is a bundle of muscle fibers called?
myofiber
Fascicle
Define myofibril
organelle in a muscle fiber composed of filaments
Define endomysium
Perimysium
Epimysium
What do these 3 join together to form?
Endo- CT surrounding a fiber
Peri- surrounds fascicle
Epi- surrounds entire muscle
Tendons
What does eccentric mean
Multi-nucleated (skeletal muscles)
Define aponeurosis
*fill in
related to CT and tendons
Slide 7
What comprises a motor unit
Somatic motor neuron supplying a group of muscle fibers (1:1)
What is a neuromuscular junction
site where neuron contacts the muscle fiber
Why are skeletal muscles multi-nucleated?
During embryonic development, myoblasts fuse to form one skeletal muscle fiber
Prevents muscle fibers from being able to undergo mitosis
What is the sarcolemma?
What is the sarcoplasma?
Lemma- plasma membrane of an individual muscle fiber
Plasma- cytoplasm of skeletal muscle fibers
Where are sarcoplasm “chocked full”
contractile proteins arranged into myofibrils