apk2100c lecture exam 1 Flashcards
anterior axial regional terminology
- cephalic
- cervical
- thoracic
- abdominal
- pelvic
- pubic
anterior appendicular region terminology
- upper limb
- manus
- lower limb
- pedal
anterior cephalic components
- frontal (forehead)
- orbital
- nasal
- oral
- mental (jaw)
posterior cephalic components
- otic (ears)
- occipital (back of head)
anterior thoracic components
- sternal
- axillary (arm pits)
- mammary
anterior abdominal components
umbilical
anterior pelvic components
- inguinal/groin
anterior upper limb components
- acromial (shoulders)
- brachial (upper arm)
- antecubital
- antebrachial (forearm)
- carpal (wrist)
posterior upper limb components
- acromial
- brachial (arm)
- olecranal (elbow)
- antebrachial (forearm)
posterior back/dorsal components
- scapular
- vertebral
- lumbar
- sacral (tail bone area)
- gluteal
- perineal (b/w anus and external genitalia)
anterior manus components
- pollex = thumb
- palmar
- digital = fingers
posterior manus
- metacarpal
- digital
anterior lower limb
- coxal = hip
- femoral = thigh
- patellar = knee
- crural = leg
- fibular/peroneal = the outter region of legs
posterior lower limb
- femoral = thigh
- popliteal = back of knees
- sural = calf
- fibular/peroneal
anterior pedal
- tarsal = ankle
- metatarsal
- digital = toes
- hallux = big toe
posterior pedal
- calcaneal = heels
- plantar = bottom of foot
body planes
- sagittal
- coronal/frontal
- transverse/horizontal
sagittal plane
vertical plane tht divides into left and right sides
- Midsagittal = cut is thru midline
- Parasagittal = cut into left and right, but not directly along midline
coronal plane
divides body or organ into anterior and posterior portions
transverse/horizontal plane
divides body/organ into superior and inferior portions
body cavities
- Dorsal body cavities
- Cranial
- Vertebral canal or spinal cavity - Ventral body cavities
- Thoracic
- Abdominopelvic
cranial body cavity (dorsal)
contains and protects brain; Formed by cranial bones
vertebral canal/spinal cavity (dorsal)
formed by bones of vert. Column
Contains & protects spinal cord
meninges
layers of protective tissue tht line the cranial cavity and vertebral canal
thoracic cavity
- Pleural = lungs; we have 2 pleural cavities, one for each lung
- Mediastinum = has the heart, esophagus
Abdominopelvic Cavity
Closed cavities; not open to external environment
body membranes
- mucous
- serous
mucous membranes
lines cavities tht are open to the outside environment
- Cells secrete mucous
- Ex: Oral and nasal cavities, vagina, anus
serous membranes
lines cavities tht are closed to the outside environment
Can secrete serous fluid (lubricant, reduce friction)
cells
all living orgs are cellular in nature; smallest living units; human bod has 200+ types of cells
functions:
1. Obtain and use nutrients
2. Dispose of wastes
3. Replicate/regenerate/repair
These functions r carried out by the cell’s organelles
main components of a cell
- Plasma membrane
- Nucleus
- Cytoplasm
plasma membrane
fluid mosaic model; made of phospholipid bilayer (hydrophilic heads, hydrophobic tails)
contains:
1. cholesterol
2. associated proteins - integral (+ transmembrane) & peripheral proteins
3. glycoproteins
4. glycolipids
cholesterol (in cell membrane)
majority are along the fatty acid tails; avoids water
- Found among lipid tails of the bilayer; 4 ring structure
- Only found in animal cells
- function: Structural integrity of the plasma membrane
integral proteins
embedded within plasma membrane
- more specific type of integral protein = transmembrane protein: spans entire bilayer
peripheral proteins
loosely associated with the plasma membrane; can be intracellular or extracellular (outside of cell)
phospholipids
Amphipathic
Dynamic arrangement
Cr8s framework for the plasma membrane
Makes up 75% of membrane lipids
Glycolipids
Only found in layer facing ECF; doesn’t face inside cell
function: Cellular adhesion and recognition
function of plasma membrane
- Protective barrier
- Cellular communications (via receptor proteins)
- Regulated movement of substances in/out (membrane transport)
membrane transport
- Plasma membr is selectively permeable; some solutes simply diffuse across bilayer - no proteins nor ATP needed
- Integral prots act as transporters & channels to assist in the entrance of impermeant (can’t cross membrane) molecules
•Carriers = passive transport
•Pumps = active transport
active transport
requires ATP + transmembrane prot.
passive transport
no ATP required
- simple diffusion - soluble molecules move directly across
- osmosis - requires aquaporins (protein channel) to transport h2o
- facilitated diffusion - requires integral protein
endocytosis
transport using vesicles; Vesicles are membrane compartments made of phospholipids; brings materials into the cell (aka endosomes)
3 types:
1. phagocytosis
2. pinocytosis
3. receptor-mediated endocytosis
phagocytosis
- cell-eating; bring lrg molecules/macromolecules into the cell; plasma membrane detects something it wants, and it reaches up and out, forms pseudopods (the extensions in pic 1) and reach out and pinch off
- forms membrane compartment and bring materials into the cell
- don’t need specific signal
pinocytosis
- cell-drinking; bring smaller solids often dissolved w.in ECF into the cell; no pseudopods
- invagination occurs instead and top portion of membrane pinches off to form vesicle
- don’t need specific signal
Receptor-mediated endocytosis
requires ligand to bind to the receptors which generaled signal for vesicles to bring materials in; SPECIFIC
exocytosis
remove material from inside cell; involves vesicle; vesicle fuses with PM and incorporates itself into the PM; ends up releasing the materials contained
cytoplasm
inside of cell
1. cytosol
2. organelles
3. inclusions
cytosol
jelly-like fluid in which all other intracellular elements are suspended
- contains: Water, ions, enzymes
- Site of many chem rxns
organelles
specialized structs w/in a cell tht have characteristic shapes and perform specific functions
inclusions
temporary structures; pigments, crystals of protein, food stores; not organelles bc dont have specific function or shape
- ex: food stores glycogen granules, lipid droplets - can be broken down
basic organelles
- mitochondria
- nucleus
- ribosomes
- endoplasmic reticulum
- golgi apparatus
- lysosome
- peroxisome
- cytoskeleton
- centrosomes and centrioles
mitochondria
- E production; double membrane organelle
- Outer mitochondrial membrane
- Inner mito. Membr; is folded; Folds called CRISTAE - incr surface area = pack more proteins and enzymes to maximize atp production
- Mitochondrial matrix = space inside mitochondrial membrane
- Space in between membranes = intermembrane space
- Has its own DNA; circular, has no protective mechanism = sensitive to damage from free radicals
ribosomes
- non-membranous organelles; functions in protein synthesis; made of proteins + ribosomal RNA
- Have 2 subunits; on their own, the subunits will not function properly
•In actuality, smaller subunit on bottom and large one on top in prot synthesis
•Location: Found in cytosome - free floating “free ribosomes”; attached to ER (rough)
endoplasmic reticulum/ER
- CONTINUOUS structures, not separate structs.; network within the cytoplasm
- network of membrane-enclosed cavities (flattened sacs or tubules)
- Rough ER: protein synth
- Smooth ER: (lipid metabolism) making/breaking down fats & calcium storage; more tubular
- RER: Flattened sacs = cisterns/cisternae
- Nuclear envelope exvaginates to form the RER & SER
golgi apparatus
- membranous organelle; have some kind of cavity associated with it; sorting center
- every time we synthesize materials from the ER (proteins or lipids), they need to be modified and sorted in the golgi
- Proteins from RER transported to golgi via transport vesicle; transport vesicle fuses with membrane of golgi to release materials
- Transport vesicle: within cell
- separatory vesicle secretes materials OUTSIDE OF cell
- has cis vs trans face
cis phase
material arrives at CIS FACE/aka receiving side of golgi - always will be the closest side facing the SER or RER
trans face
shipping side - new vesicle pinches off from golgi membrane and material exits out
lysosomes
digest, break down materials; membranous
- Very acidic, have enzymes that break down materials, like not working proteins and old parts of organelle; debris via endocytosis and degraded
peroxisomes
smaller than lysosomes; DETOX; aka peroxide bodies; predominantly in liver and kidney cells
- Neutralize SMALLER toxic waste; assist in breaking down long fatty acid chains
- Free radicals = very destructive - have extra e- and can damage surrounding structures - OXIDASE enzyme turn free radicals into h2o2; H2o2 is still damaging, but not as bad as free radical
- catalase converts h2o2 to h2o and o2
cytoskeleton
elaborate network of rods running throughout the cytoplasm; functions like bones, muscles, and ligaments in an organism; support cell’s shape and produces movements in some cases
- includes: microfilaments, intermediate filaments, and microtubules
microfilaments
- smallest; ex: actin; actin made of small globular actin molecules aka G actin
- Found: Edge of cell
- MICROVILLI: non-motile, microscopic, finger-like projections of the plasma membrane; actin on the side; actin ≠ microvilli - actin act as standing rods inside microvilli to keep it upright/give it structure
Incr SA of a cell for ABSORPTION - Found in absorptive cells (ex: epithelium lining small intestines)
intermediate filaments
tough, insoluble protein fibers constructed like woven ropes - larger than microfilaments
- Found: throughout the cell
- Stabilize organelle position in the cytosol and attach cells to 1 another
microtubules
largest, hollow tubes of spherical protein subunit; like a coil
- Project outward from the CENTROSOME
- Determine cell’s overall shape
- Also involved in cellular mvmnt (cilia and flagella)
•Flagella: propelling tail; ex: sperm tail
•Cilia: along cell surface, hair-like, brush things across cell surface - stroke like mvmnt
Ex: cells in respiratory system have lots of cillia to move mucous to prevent build up when u have a cold
centrosomes and centrioles
Forms microtubules and aids in cellular division
- Centrioles = made of microtubules; microtubes will spout from centrioles during cellular division
nucleus
- Nucleolus: site of ribosomal RNA synth
- Chromatin = genetic material
- Nuclear envelope/nuclear membrane = double membrane
- Nuclear pores: allow material to exit or enter nucleus
tissues
- Basic components of all tissues: cells + extracellular matrix
- 4 basic tissue type:
1. epithelial
2. connective
3. muscular
4. nervous
epithelial tissue function
covers body surfaces and lines hollow organs, body cavities, duct, and forms glands
- Protection of underlying tissues
- Selective barrier:
- Secretion - release products onto the free surface; excretion of wastes
- Absorption
- Diffusion filtration
- Sensory reception
connective tissue functions
protects, supports, and binds organs
- Stores E as fat, provides immunity
muscular tissue function
gener8 the physical force needed to make body structures move and gener8 body heat
nervous tissue function
detect changes in body and responds by gener8ing nerve impulses (control)
Epithelial tissue
- Cells arranged in continuous sheets bc they line/cover things; can be single or multiple layers
- Cells are closely packed and held tightly juntos; little to no extracell matrix
- Found @ a boundary b/w 2 diff environments
Ex: epithelial tissue lining digestive tract - need to absorb nutrients in food; have tissue separating where absorption is and where bloodstream is - Always have a free surface - one side is anchored to something and one side is facing a free surface (the cavity or hollow area)
Special features of epithelia
- High cellularity - lots of cells
- Specialized contacts - allows cells to adhere to e/o
- Polarity
•Apical surface - faces body surface, body cavity, lumen, duct; side facing hollow cavity, the external environment
•Basal surface - opposite of apical surface, adheres to basement membrane; the side that is anchored/bound - Support by connective tissue - basement membrane
- Avascular
- Nervous innervation
- Regeneration - high mitotic activity
basement membrane
has 2 layers: the basal lamina is secreted by the epithelium and the reticular lamina is pt of the underlying connective tissue
Classification of epithelia
- Arrangement of cells into layers
•Single layer of cells = “simple”
•Multiple layers stacked on top of e/o = “stratified” - Shapes of cells:
•Squamous - flat, tile-like
•Cuboidal - nucleus is more spherical and centered
•Columinar - nucleus is more oval and off-center; nucleus more towards basal surface
Types of epithelial tissue
- Simple squamous epithelium
- Simple columnar
- Pseudostratified columnar epithelium
- Stratified squamous epithelium
- Stratified cuboidal
- Stratified columnar
Lateral surface features of epithelium
- Specialized contact:
1. tight junctions
2. desmosomes
3. gap junctions
tight junctions
interlocking junctional proteins fuse plasma membrane of 2 side by side cells juntos; impermeable junctions prevent molecules from passing
desmosomes
anchoring junctions bind adjacent cells together and help form an internal tension-reducing network of fibers
- linker glycoproteins/cadherins interdigitized (act like a zipper) to anchor the cells
gap junctions
- channel b/w cells/connexon
- communicating junctions allow ions and small molecules to pass from 1 cell to the next for intercell communication
Basal surface features of epithelium
anchored to basement membrane: basal lamina
Apical surface features of epithelium:
- Microvilli: Extensions of plasma membrane, incr SA, non-motile
- Cilia: move things along surface of a cell
Glands
- epithelia tht make and secrete a product form glands
- Secretion are aqueous fluids tht usually contain proteins: hormones, mucous, sweat and oils, bile and digestive enzymes, milk
- Secretions are exocytosed
Types of glands
- endocrine
- exocrine
endocrine glands
secrete hormones DIRECTLY into ECF; hormones then diffuse into blood stream w/o a duct; effector organs are far away
exocrine glands
- secretions flow onto body surfaces or into cavities NOT INTO BLOODSTREAM
- Secretions act LOCALLY - effector.target organs are nearby
- Multicellular exocrine glands: multiple cells form a gland tht secretes products via a duct (Sweat glands)
- Unicellular exocrine glands: one-celled gland (ex: goblet cell)
goblet cell
pt of exocrine gland
- special feature: have secretory vesicles containing mucin
- mucin is a glycoprotein that is exocytosed onto the free surface - once it combines with free water, it makes mucus
Multicellular exocrine gland
has 2 parts
1. separatory portion/glandular epithelium
2. duct
***surface epithelium is NOT pt of the exocrine gland
Types of multicellular exocrine glands
- simple tubular (ex: intestinal glands)
- simple branched tubular (stomach/gastric glands)
- compound tubular (duodenal glands of small intestine)
- simple alveolar (no important ex in humans)
- simple branched alveolar (sebaceous/oil glands)
- compound alveolar (mammary glands)
- compound tubuloalveolar (salivary glands)
*simple duct structure = duct is unbranched
*compound structure = branched duct
Covering and lining membranes
- cutaneous membrane = skin
- mucous membrane
- serous membrane
mucous membrane
line OPEN cavities and organs
- ex: tubes of respiratory, digestive, reproductive, and urinary systems
serous membranes
line CLOSED cavities
- ex: thoracic and abdominal cavities
Connective tissue (CT)
most diverse and abundant type of tissue
- 4 main types:
1. cartilage
2. proper
3. bone
4. blood
general characteristics of CT
- made of few cells; CT made of cells and matrix (extracellular matrix)
- lots of extracell matrix (opp of epithelium)
- Have common embryonic origin: come from mesenchyme
- Descendant cells: fibroblast, chondroblast, osteoblast, hematopoietic stem cell
• these immature cells retain the capacity for mitosis and SECRETE THE MATRIX - mature cells have reduced capacity for cell division; mostly involved in matrix maintenance
Fibroblast development
Fibroblast -> fibrocyte -> connective tissue proper -> 1. Loose CT and 2. Dense CT
loose CT proper
- have 3 types
1. areolar
2. adipose
3. reticular
*TIP: LARA
Loose
Areolar
Reticular
Adipose
dense CT proper
- have 3 types;
1. regular
2. irregular
3. elastic
TIP: DIRE
Dense
Irregular
Regular
Elastic
Chondroblast development
chrondroblast (immature cartilage cell) -> chondrocyte (mature cartilage cell) -> cartilage
cartilage
- 3 types
1. Hyaline cartilage
2. Fibrocartilage
3. Elastic cartilage
TIP: CHEF
Cartilage
Hyaline
Elastic
Fibrocartilage
osteoblast development
Osteoblast -> osteocyte -> osseous/bone
bones
- connective tissue
- 2 types: compact bone & spongy (cancellous) bone
Hematopoietic stem cell development
Hematopoietic stem cell -> blood cells and macroprophages
CT extracellular matrix components
matrix contains protein fibers embedded in a fluid, gel, or solid ground substance
- Ground substance - material tht fills space b/w cells and fibers
•can be fluid, semifluid, gelatinous, or calcified
• functions to support and bind cells, store h2o, and acts as medium for exchange b/w blood and cells
• combo of proteins and polysacchs. - Fibers: ynthesized by fibroblasts; provides strength and support for tissues; 3 types - collagen, reticular, and elastic
CT cells
- Fibroblasts
- Adipocytes /fat cells
- Mast cells
- WBCs
- Macrophages
- Plasma cells
fibroblasts
CT cell tht secretes fibers and components of ground substance
adipocytes
CT cell tht stores triglycerides
mast cells
ct cell tht produces histamine (incr blood flow) and heparin (prevents blood clotting)
WBCs
ct cell pt of immune response
- neutrophils and eosinophils
macrophages
CT cells tht engulf bacteria and cellular debris by phagocytosis
plasma cells
CT cells tht secrete antibodies
collagen fibers
- largest in diameter, rope-like structures
- strongest of the fibers; tough, flexible
- function; tensile strength; resists stretching
elastic fibers
allows for stretch and RECOIL
- intermediate diameter (long, thin fibers)
- branches form networks
reticular fibers
forms sponge-like framework
- smallest diameter
- have special collagen fibrils ; not the same as FIBERS; cluster into networks
- function: support
Case study: scurvy
- Vitamin C is necessary for cross-linkage of collagen FIBRILS to make collagen FIBERS
- collagen helps: hold teeth in place, reinforce blood vessels, wound healing
- What symptoms might u expect from someone suffering from scurvy?: Lose teeth, lots of bleeding, reduced healing
Areolar loose connective tissue
- Gel-like matrix with all 3 fiber types
- cells: fibroblasts, macrophages, mast cells, and some WBCs
- Function: wraps and cushions organs macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid
- Location: widely distributed under epithelia of body (ex: forms lamina propria of mucous membranes; packages organs; surrounds capillaries)
Adipose loose CT proper
- Matrix as in areolar CT, but v sparse; closely packed adipocytes have nucleus pushed to the side by lrg fat droplet (lipid droplet = inclusion)
- Function: provides reserve food fuel; insulate against heat loss; supports and protects organs
- Location: under skin in hypodermis; around kidneys and eyeballs; within abdomen; in breasts
Reticular loose ct proper
- Network of reticular fibers in a typical loose ground substance; reticular cells lie on network
- Function: fibers form a soft internal skeelton/stroma tht supports other cell types including WBCs, mast cells, and macrophages; more associated with immune system
- Location: lymphoid organs (lymph nodes, bone marrow, and spleen)
- looks like cherry blossom tree
Dense regular connective tissue proper
- Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast
- Function: attaches muscles to bones or to muscles; attaches bones to bones; withstands gr9 tensile stress when pulling force is applied in 1 direction
- Location: tendons, most ligaments, aponeuroses
Dense irregular CT proper
- Primarily irregularly arranged collagen fibers, swirly pattern/marbling; some elastic fibers; major cell type is fibroblast; defense cells and fat cells also present
- Function: able to withstand tension exerted in many directions bc swirly/irregular placement; provides structural strength
- Location: fibrous capsules of organs and of joints, dermis of the skin, submucosa of digestive tract
Dense elastic CT proper
- Predominant fiber type = elastic, not collagen
Squiggly pattern - Function: ^allows recoil of tissue following stretching; maintains pulsatile flow of blood thru arteries; aids passive recoil of lungs following inspiration
- Location: walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes
Hyaline cartilage
- amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and, when mature (chrondocytes), lie in lacunae (cavity within this type of cartilage where the chondrocyte is)
- Function: supports and reinforces; serves as resilient cushion; resists compressive stress
- Location: forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx
Elastic cartilage
similar to hyaline cartilage, but more elastic fibers in matrix; hyaline cartilage is much more opaque, while elastic fibers are more visible in elastic cartilage
- Function: maintains the shape of a structure while allowing gr8 flexibility
- Location: supports the external ear (pinna/outer portion of ear NOT EARLOBE); epiglottis; earlobe is made of areolar loose connective tissue proper and adipose tissue
fibrocartilage
- matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate
- Function: tensile strength w/ the ability to absorb compressive shock
- Location: intervertebral discs (between vertebrae); pubic symphysis; discs of knee joint
Osteocyte/bone
- Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae; very well vascularized
- Function: supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones = site for blood cell formation (hemtaopoiesis)
2 types of bone: compact and spongy
blood
- Fluid form of connective tissue; red and wbcs in a fluid matrix (plasma)
- Function: transport respiratory gases, nutrients, wastes, and other substances
- Location: contained within blood vessels
erythrocytes
RBCs
- Function; transports respiratory gases; biconcave disc shape; no organelles inside - ANUCLEAR
Muscle Tissue
- Skeletal - body movement
- Cardiac - blood movement - heart to lungs to body - blood back into heart
- Smooth - lots of functions (move things through GI tract, intestines, etc)
General function: movement
skeletal muscle
long, cylindrical, multinucleate cells; obvious striations
- Function: voluntary mvnmt, locomotion, manipulation of the environment; facial expression
- Location: in skeletal muscles attached to bones or occasionally to skin
cardiac muscle
branching, striated, generally uninucleate cells tht interdigitate at specialized junctions (intercalated discs)
- Function: as it contracts, it propels blood into the circulation; involuntary control
- Location: only in walls of the heart
smooth muscle
spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets
- Function: propels substances or objects (foodstuffs, urine, a baby - uterine contractions during labor), along internal passageways, involuntary control
- Location: mostly in the walls of hollow organs (GI tract, stomach, intestines)
Smooth Muscle vs Dense Reg CT Proper
- Smooth: nuclei INSIDE fibers
- Dense regular CT: nuclei wedged BETWEEN fibers - look for gaps; Nuclei lined up in rows one after another
nervous tissue
main tissue of nervous system
- Brain, spinal cord, nerves
- Contains 2 types of cells: neurons & neuroglia/glial cells
- Neurons are branching cells; cell processes tht may be quite long xtend from the nucleus-containing cell body; also contributing to nervous tissue are nonconducting supporting cells, neuroglia (not illustrated)
- Functions: transmit electrical signals from sensory receptors and to effectors (muscles and glands) tht control the activity of the effector organs
- Location: brain, spinal cord, and nerves
glial cells
Glial cells are more abundant; not really used for signaling, but they support the neurons
Regenerative Capacity of Tissues
- Good regenerators: bone, areolar & dense irregular CT; blood + epithelia
- Mediocre: smooth muscle
- Poor: skeletal muscle, tendons, ligaments (ACL tear), cartilage (ex: Achilles tendon = dense regular CT proper - requires surgery to reattach tendon)
- Almost no regeneration: cardiac muscle, nervous tissue
integumentary system
- Skin = integument; largest organ of the body
- Accessory organs: hair, nails, oil and sweat glands
layers of the skin
1: epidermis = top surface
2: dermis
HYPODERMIS IS NOT TECHNICALLY PART OF THE SKIN
functions of the skin
- Thermoregulation
- Protection - physical barrier
- Sensory reception - nerve endings within the skin
- Excretion
- Vitamin d production
epidermis
most superficial layer; AVASCULAR; made of keratinized stratified squamous epithelium
4 types of epithelial cells
- Keratinocytes - >90%, majority of cells in epidermis; physical and mechanical protection, produce antibiotics and enzymes that detoxify harmful chemicals
- Melanocytes - produce pigments for the skin (tan, skin tone)
- Langerhans/dendritic cells - immune function
- Merkel (tactile epithelial cells) - allow us to sense pressure and touch
thin skin
areas of skin where there is little friction; most of the body; 4 epidermal layers
thick skin
areas of skin where friction commonly develops; palms, feet, fingertips
- 5 epidermal layers
Layers of the thin epidermis
4 strata
in order of deep to superficial:
1. stratum basale
2. stratum spinosum
3. stratum granulosum
4. stratum corneum
Stratum basale
deepest epidermal layer; anchored, most basal layer
- 1 row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers.
- Only 1 row of keratinocytes; when melanocytes produce melanin, they deposit the melanin into nearby keratinocytes
- See occasional melanocytes and dendritic cells
- Has high mitotic activity/cell division; the more cells we cr8, the more piling up occurs, pushes everything up
stratum spinosum
several layers of keratinocytes unified by desmosomes.
- cells contain thick bundles of intermediate filaments made of pre-keratin
- Tonofilaments: intermediate filaments made of prekerotin found in the keratinocytes of the stratum spinosum
stratum granulosum
1 to 5 layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyalin granules
- Granules: melanin and lamellar granules - lamellar granules make skin more water resistant bc it is lipid based
- Cells flattened bc they’re missing organelles
stratum corneum
- most superficial; 20-30 layers of dead cells
- represented only by flat membranous sacs filled with keratin; glycolipids in extracellular space
- As we get further away from stratum basale, can’t get enough nutrients so cells begin to die off (bc epidermis is avascular)
layers of thick epidermis
superficial to deep:
- Stratum corneum
- Stratum lucidum: only in thick epidermis; slightly translucent
- Stratum granulosum; dark layer bc melanin
- Stratum spinosum
- Stratum basale
tans and tattoos
- Epidermis is replaced ~every month
- How long does tan last? - few weeks - lose tan by previous cells sloughing off and being replaced by new ones
- What aspects of a tattoo reflect the structures present in the epidermis? - ink is NOT placed in epidermis bc the epidermis is constantly being replaced so tattoo will disappear - needs to be in a deeper layer - needs to go in area that is VASCULAR (tattooing involves BLEEDING - epidermis is AVASCULAR)
skin tone pigments
- Melanin: pigment produced in hair and skin; brown
- Carotene: orange color
- Hemoglobin: in blood, red color
melanin
2 types: eumelanin and pheomelanin
- produced in skin and hair
- Melanocytes produce a protein (melanin) which places itself b/w the sun and a cell’s nucleus
- Melanocytes takes amino acid tyrosine and converts it into melanin; then transfer melanin into kertinocytes; once released inside, melanin granules surround the nucleus - Protects nucleus from UV rays
- # of melanocytes is the same for everyone; differences in skin color due to amt of pigment produced (melanin) and transferred to keratinocytes
- Light skin: melanin clumped near nucleus; breaks down quickly
- Dark skin: melanin spread throughout keratinocytes; breaks down slowly
eumelanin
imparts brown to black color
pheomelanin
imparts yellow to red colors particularly noticeable in hair
albinism
cannot produce any melanin due to genetic disorder
- Have melanocytes, but can’t convert tyrosine into melanin
- Usually due to in an inability to produce tyrosinase enzyme
- Results in translucent hair, skin, and eyes; display pink or red eyes
dermis
- Mostly connective tissue, very tough
- where vast majority of nerve ends
- Many other structures in the dermis: blood vessels, lymphatic vessels, nerves
- Has 2 regions:
- Most superficial = papillary layer
- Deeper layer = reticular layer
- contain appendages of the skin, which are derived in epidermis but located in dermis
papillary layer of dermis
most superficial; (darker pink layer with curvy look)
- areolar loose connective tissue proper makes up this layer
- includes dermal papillae
reticular layer of dermis
deeper layer
- formed by dense irregular connective tissue proper; FORMS FINGERPRINTS
- “reticular” = network - refers to the network of collagen fiber within the dense CT
Dermal papillae
small projections of the papillary dermis into the overlying epithelium
- enhances surface area for nutrient/gas exchange & strengths the dermal-epidermal junction
- keratinocytes get nutrients via diffusion from the underlying dermal layer since it is avascular
- Dermal papillae is NOT what makes ur fingerprints bc they dont match the epidermal ridges
what forms fingerprints?
Epidermal ridge = peaks and valleys tht form fingerprints; underlying mounds of tissue tht protrudes up to form fingerprints
cleavage lines
- separations or less dense regions of collagen bundles in the reticular dermis cr8 invisible cleavage lines in the skin
- Incisions made along the cleavage lines tend to gape less and heal more quickly than incisions made across cleavage lines
- DONT CUT PERPENDICULAR TO CLEAVE LINES = longer to heal
hypodermis
- subcutaneous layer of CT; NOT PART OF THE SKIN
- made mostly of adipose loose CT proper
- Varies in thickness
- Projects underlying structure, insulates, and stores E
- Contains large blood vessels, lymphatic vessels, and nerves whose branches extend into the dermis
Cutaneous sensation
- many structures are imbedded in the dermis
- Most of these structures are derived from the epidermis
•Hair follicles
•Sweat glands
•Oil glands
Some structures are from underlying nerves which transmit info to the CNS
free nerve endings
found in epidermis
senses pain
- u want to sense pain immediately bc u want to avoid trauma ASAP before u take serious damage
nerves in dermis
- heat, cold, light touch - close to epidermis-dermal junction bc u want to sense this asap; are encapsulated/enclosed
- Deeper in dermis: strong pressure
- Nerves around hair follicle to sense hair movement
Appendages of the skin
derived from epidermis, but mostly located in dermis
- Nails, hair & hair follicles, sebaceous/oil glands, sweat glands
nails
scale-like modification of the epidermis containing dead keratinocytes full of HARD keratin
Superficial nail structures
- White part of nail = free edge of the nail (the part u cut off)
- Nail plate = pink part = directly over the digit; pink bc nail is v transparent bc of dead keratinocytes so blood supply/capillaries are more visible
- Lunule = crescent shape at proximal end of nail; where nail matrix is = where cells proliferate to generate more nail; tht region is very thick so its white and not pink
- Lateral nail fold
- Eponychium = cuticle
deep nail structures
- Free edge
- Nail plate right on top of nail bed
- Nail bed = made of epidermal cells
- Nail root = hardened pt of nail tht covers the nail matrix
hair
flexible columns of dead keratinocytes full of HARD keratin
- 2 parts:
- shaft: hair above the surface
- root: below the surface
Hair and hair follicle anatomy
3 layers
- Medulla = inner most; inner pore
- Cortex - surrounds medulla
- Cuticle - outermost layer
hair follicle
sheath that is around the hair itself
- made of external and internal root sheath
- arrector pili muscle associated with it
- sebaceous glands are associated with it
External root sheath (hair)
most superficial to the hair; derived from stratum basale
Internal root sheath (hair)
- closest to the hair
- derived from stratum corneum of epidermis tht inavginates downward - as soon as it invaginates around the hair, it is the internal root sheath
hair bulb
(looks like a tooth); where blood vessels come in to provide nutrients to cell to hair matrix in the bulb
arrector pili muscle
directly attached to hair follicle
- when u get goosebumps, tht is due to the arrector pili muscle contracting, pulling the hair up - it kinda gapes the skin a little, giving the goosebump look
types of hair
Straight: hair matrix is circular
Wavy: hair matrix is like a bean shape
Curly: oval shape
sebaceous glands
- located everywhere except the plantar and palmar regions; duct dumps into a hair follicle; simple alveolar type of exocrine gland
sebum
- keeps hair/skin soft
- protects against brittle hair/skin
- protects epidermis from cracking
- collects dirt
- impedes water loss across skin
sweat glands/sudoriferous
tubular exocrine gland
2 types: eccrine & apocrine
eccrine sweat glands
palms, soles, forehead, almost every where
- true “sweat”; watery
- thermoregulatory function
- duct opens directly onto skin surface
apocrine sweat glands
axillary, anal, genital areas only
- duct opens to hair follicle
- milky “sweat” bc it mixes with sebum and other substances in the follicles - so this results in body odor
- no thermoregulatory function
