M2 Study Guide Flashcards
what are neurotransmitters synthesized by
neurons
where are neurotransmitters stored
synaptic vesicles in presynaptic axon terminal (knobs)
what are neurotransmitters released from
vesicles that are fused to the membrane of the synaptic knob secondary to the actions of Ca2+, synaptotagmin, and SNAREs
what do neurotransmitters bind to
receptor on postsynaptic neuron (or effector)
what do neurotransmitters trigger
physiological response downstream by initiating graded excitatory or inhibitory postsynaptic potential (EPSPs and IPSPS)
agonist
mimic action of neurotransmitter
antagonist
block action of neurotransmitter
facilitator
enhance effect of neurotransmitter
inhibitor
reduce effect of neurotransmitter
what binds to an ionotropic receptor
ligand
what does the ligand do after binding to an ionotropic receptor
opens the channel and allows an influx of that ion through the channel into the postsynaptic cell (and therefore, altering mem. potential)
what binds to a metabotropic receptor
water-soluble ligand (1st messenger)
what happens after a water-soluble ligand binds to a metabotropic receptor
triggers a G-protein-second messenger mechanism which activates the opening of ion channels of another integral protein within cell membrane, allowing for an influx of ions into the postsynaptic cell (therefore, altering mem. potential)
cholinergic
neurons that utilize ACh
where is ACh found
CNS and PNS
what does ACh act on
nicotinic receptors located in spinal cord, autonomic ganglia, and neurotransmitter junction.
muscarinic receptors located in remainder of CNS
what do nicotinic receptors utilize
utilize ion channels = ionotropic receptors
what do muscarinic receptors utilize
G-proteins/second messengers = utilize metabotropic receptors
where is ACh degraded and by what
degraded in synaptic cleft by acetylcholinesterase
what does acetylcholinesterase degrade ACh into
acetate and choline
how does ACh correlate to Alzheimer’s
cholinergic neurons degenerate = loss of ACh as neurotransmitter synthesize within these neurons (synaptic knob).
Loss of postsynaptic neurons that would have responded to ACh exacerbate disease
clinical signs of Alzheimer’s
declining language
memory loss
what are catecholamines derived from
amino acid tyrosine
what do catecholamines include
dopamine
norepinephrine
epinephrine
what is parkinson’s disease characterized by
loss of dopamine-releasing neurons within substantia nigra of the basal nuclei (basal ganglia) deep within brain
what are the basal ganglia responsible for
motor control
what are the effects of Parkinson’s
loss of motor control including abnormal (involuntary) body movements, muscle tone, and posture.
increased severity of the movements is indicative of greater loss of neurons.
what is Parkinson’s initially treated with
L-dopa to treat symptoms only (NOT the disease).
this intermediate is able to cross the blood-brain barrier vs. dopamine
what do norepinephrine and epinephrine bind to
alpha- and beta-adrenergic receptors
are alpha- and beta-adrenergic receptors ionotropic or metabotropic
metabotropic - utilize G-protein mechanism
pathway from starting amino acid (tyrosine) and downstream products
Tyrosine –tyrosine hydroxylase–> L-Dopa –dopa decarboxylase–> dopamine –dopamine beta-hydroxylase –> norepinephrine –phenylethaolamine N-methyltransferase –> epinephrine
what do MAO inhibitors degrade
enzymatic degradation of catecholamines
what do MAO inhibitors increase
the amount of catecholamines in the synapse
what are MAO inhibitors used to treat
mood disorders and various classes of depression by increasing motivation and pleasure
what is serotonin derived from
amino acid tryptophan
what is the ‘sleepy’ amino acid
tryptophan
what does serotonin regulate
sleep and emotions
what are selective-serotonin reuptake inhibitors (SSRIs) utilized for
treating mood disorders
what is histamine derived from
amino acid histidine
most common neurotransmitter in CNS
glutamate
what do AMPA ionotropic receptors conduct and how
fast EPSPs by rapid influx of Na+ into the postsynaptic cell
what do NMDA ionotropic receptors open and how
open in response to membrane depolarization secondary to the opening of the of AMPA receptors by bumping Mg2+ plug in this receptor.
opening of this receptor triggers a chain of events that will ultimately signal presynaptic cell to continue synthesizing and releasing glutamate to allow for longer-lasting response.
inhibitory amino acids
gamma-aminobutyric acid (GABA) and glycine
excitatory amino acid
glutamate
what is the most common inhibitory neurotransmitter
GABA - dampens brain’s neural activity
what is nitric oxide (NO) a major player in
blood vessel dilation (vasodilation) via smooth muscle relaxation
how is NO synthase triggered and what does it activate
G-protein/second messenger cascade triggers enzyme (NO synthase) to activate NO, which activates another cascade in the adjacent smooth muscle causes relaxation (therefore, vasodilation)
how is NO different from other neurotransmitters
not stored in vesicles and synthesized only on an as-needed basis in the postsynaptic cell and it acts on the presynaptic cell (retrograde communication)
what can too much NO cause
proinflammatory, therefore, cytotoxic
what lipids are neurotransmitters
those derived from arachidonic acid (eicosanoids) and include prostaglandins, thromboxanes, and leukotrienes
what are endocannabinoids derived from
arachidonic acid
what are endocannabinoids released from and act on
released from the postsynaptic cell (like NO) and act antagonistically on the presynaptic cell in response to a neurotransmitter binding to the postsynaptic receptor.
overall result is modulation of the signal in the postsynaptic pathway that dampens 1. transmission of pain signals in the CNS and 2. inflammatory response in many tissues
neurotransmitters of interest
nitric oxide (NO)
lipids
carbon monoxide
hydrogen sulfide
ATP/adenosine
what do g-proteins serve as
a ‘switch’ to couple a receptor to an ion channel in the cell membrane
general steps of g proteins
- ligand binds to transmembrane receptor (‘first messenger’) and changes its conformation (ex. shape).
- change in receptor conformation allows for binding of the g protein subunit where GDP bound to the g protein is replaced with GTP, ‘activating’ g protein.
- activated GTP-bound g protein binds to an enzyme that is embedded in the cell membrane, activating/inhibiting this enzyme.
- once enzyme/ion channel has been activated, GTP on the g-protein alpha subunit is cleaved into GDP and phosphate; g-protein is now inactivated. - specific second messenger is activated by the enzyme when bound by the g-protein:
- cyclic AMP (cAMP)
- cyclic GMP (cGMP)
- diacylglycerol (DAG)
- inositol triphosphate (IP3)
- Ca2+
- arachidonic acid - second messenger activates particular protein kinase which will stimulate (or inhibit) signal pathways within that cell
what does inactive g protein within the postsynaptic cell’s cytoplasm bound to
guanosine diphosphate (GDP)
what happens after ligand (ex. first messenger) binds to the receptor
g protein binds to the receptor protein as well but on the intracellular side
what does GTP activate
g protein
what is GDP replaced with
guanosine triphosphate (GTP)
what does g protein bind to on the intracellular side
another transmembrane protein that is an enzyme, which catalyzes ATP into a second messenger
what does the second messenger activate
another enzyme, a kinase, which triggers modifications of the numerous activities taking place within the cell
will the binding of one ligand to a receptor significantly amplify the number of final products
yes.
these ligands are very potent in a response
what are extracellular matrix components secreted by
resident cells
what is the collagen precursor and what is comprised of
procollagen and it is comprised of 3 identical polypeptide strands in a helix.
ends are capped to prevent degradation and packaged within vesicles by golgi complex and is transferred out of the cell by exocytosis.
ends are cleaved from procollagen molecules and a series of mostly unknown steps convert to mature collagen
what is the function of collagen
provides tensile strength to tissue (structural role)
what are the major types of collagen
1
2
3
what is soluble tropoelastin secreted from
fibroblasts into extracellular matrix where it undergoes posttranslational modification to form insoluble elastin
what makes up microfibrils and what do they do
fibrillin serves as the scaffold for elastin deposition that forms an inner core
characteristics of ground substance
transparent, viscous, semi-fluid gel
what do the high viscosity and osmotic pressure of ground substance help
high viscosity helps resist compression.
high osmotic pressure helps maintain fluid balance between interstitial fluid and intracellular environment and vasculature - significant enough drop in tissue osmotic pressure can result in edema due to influx of fluid into the tissue
function of ground substance
influence fluid transport and metabolic exchange
what makes up proteoglycan
GAG + core protein (binds to GAG) + linker protein (binds core protein and GAG to hyaluronic acid backbone)
what make sup proteoglycan aggregate
proteoglycan + hyaluronic acid + some collagen
what makes up extracellular matrix (ECM)
collagen
tropoelastin
microfibrils
ground substance
what are the 3 types of cartilage
hyaline
elastic
fibrous (fibrocartilage)
what does the outer fibrous layer of cartilage contain
fibroblasts and comprised of fibrous connective tissue; contain vasculature
what does the inner chondrogenic layer contain
mostly chondrogenic progenitor cells and chondroblasts.
some chondrocytes
what are the cells of cartilage proper
chondroblasts
chondrocytes
function of chondroblasts
main producer of extracellular matrix
function of chondrocytes
secrete substances to prevent blood vessel formation, so cartilage is avascular
do chondroclasts exist in carilage
no
what is lacunae
space occupied by a cell
where is hyaline cartilage and perichondrium not found
articulating surface of joints because you want to keep growth to a minimum
does hyaline cartilage have elastic fibers
no
what type of collagen is predominant in hyaline cartilage
type 2 collagen.
type 1 in outer fibrous layer of perichondrium - fibroblasts are in the perichondral sublayer and they secrete type 1 collagen
location of hyaline cartilage
tracheal bands.
bronchi.
nasal septum.
articulating bone surfaces in long bone.
growth (epiphyseal) plates of long bones.
site of initial bone repair following a fracture.
embryonic template for long bone formation.
what is the 2nd type of cartilage
elastic
what is the difference between elastic and hyaline cartilage
elastic cartilage has elastic fibers, which provides some additional flexibility compared to hyaline cartilage
what type of collagen is predominant in elastic cartilage
type 2 collagen predominant.
type 1 in outer fibrous layer of perichondrium
location of elastic cartilage
external ear (lobe).
epiglottis.
pharyngotympanic/auditory tube (Eustachian tube).
what is the 3rd type of cartilage
fibrous cartilage (fibrocartilage).
does fibrous cartilage have perichondrium
no
what is fibrous cartilage great at withstanding
compression
location of fibrous cartilage
intervertebral discs (specifically, outer annulus fibrosis).
symphyses (ex. joints between bones of breastbone as well as joint between right and left pubic bones in hip).
foramen lacerum ‘filler.’
menisci of joints.
temporomandibular joint (TMJ).
true or false: cartilage growth is limited
true
where does appositional growth occur
width.
at the external edge of the cartilage where there are more chondroblasts and more area for these cells to secrete extracellular matrix
where does interstitial growth occur
lengthwise.
occurs at center of cartilage
what is the fibrous and osteogenic periosteum
outer and inner layers on most external portion of bone
what does the fibrous layer of bone contain
fibroblasts
what does the inner osteogenic layer of bone contain
mostly osteogenic progenitor cells and differentiated osteoblasts but can also contain osteocytes
what are sharpey (penetrating) fibers
‘extensions’ of the fibrous periosteum into compact bone
what do sharpey fibers allow for
better ‘adherence’ of the periosteum to the underlying bone given that the periosteum serves as attachment sites for tendons and ligaments
what cells are in bone
osteoblasts
osteocytes
osteoclasts
what are osteoblasts
main builder of bone by secreting osteoid into extracellular matrix
what are osteocytes
secondary builder of bone.
bone maintenance/remodeling
what are osteoclasts
maintenance/remodeling –> dissolve bone
what do osteoclasts secrete to break down organic component of the osteoid
enzymes
what are the organic components of the osteoid
collagen
GAGs
glycoproteins
what do osteoclasts secrete to break down inorganic salts
hydrochloric acid (HCl)
what are the inorganic salts of bone
hydroxyapatite
what is liberated when organic components of the osteoid and inorganic salts are broken down
calcium and phosphorus
what is calcium vital for
muscle contraction
neurotransmitter release
blood clotting pathway
what is phosphorus utilized in
forming ATP and the phospholipids that contribute to the cell membrane
what ions are incorporated into the hydroxyapatite crystals
sodium
chloride
magnesium
what are the organic components of the extracellular matrix of bone
collagen
GAGs
glycoproteins
what do organic components contribute to
bone’s tensile
what do low quantities of inorganic components in bone make it
excessively flexible (taffy like)
what are the inorganic components of extracellular matrix of bone
mainly of calcium phosphate (Ca3(PO4)2 and calcium hydroxide (Ca(OH)2 that incorporate to form hydroxyapatite Ca10(PO4)6(OH)2
what do inorganic components contribute to
increase bone’s rigidity while also allowing for a small amount of flexibility
what do low quantities of organic components in bone do
make it brittle
what are the different structures of Haversian system/osteon
concentric lamellae
haversian (central) canal
volkmann (perforating) canal
canaliculi and lacunae
what do lacunae contain
space-occupying osteocytes
what is found within canaliculi
the cell membrane extensions of osteocytes.
extend towards a canal containing vasculature
what are outer and inner circumferential lamellae comprised of
compact bone surrounding the bone’s external (adjacent to the periosteum) and internal (adjacent to the endosteum and inner core, the medullary cavity) periphery
what are interstitial lamellae comprised of
compact bone between osteons
what are trabeculae
spicules of bone within medullary cavity
what are howship lacunae
cavities occupied by an osteoclast
what does the innermost medullary cavity contain
vasculature
lymphatics
nerves
marrow (red or yellow)
what is intramembranous ossification
formation of flat bones (ex. skull, facial bones)
what is endochondral ossification
formation of long bones (ex. arm and leg bones).
derived from a miniature hyaline cartilage template
why is the bone collar formation special
bone collar formed initially is intramembranous ossification.
bone that is developed is forming around the hyaline cartilage template
where is the epiphysis
located at the ends of long bone
what is the epiphysis the location of
secondary ossification center that forms after the primary ossification site where cartilage is calcified and then chondrogenic cells are replaced by osteogenic cells that begin producing osteoid (organic component of ECM)
what type of bone marrow does the epiphysis contain and what is it a common site for
contains red bone marrow within the spongy region and serves as the most common site for hematopoiesis
what is the metaphysis
small, transitional region between epiphyses and diaphysis
what is the metaphysis the location of
the growth plate (at the metaphyseal/epiphyseal border).
plate decreases in size with age prior to closing at adolescence due to its ossification to become the epiphyseal line
what are the zones of the growth plate
zone of reserve (resting) cartilage.
zone of proliferation cartilage.
zone of maturation/hypertrophy.
zone of degeneration (calcified) cartilage.
zone of ossification.
zone of reserve (resting) cartilage
typical hyaline cartilage with chondrocytes in small clusters
zone of proliferation cartilage
mitotic activity of chondrocytes increase, extracellular matrix rich in proteoglycans
zone of maturation/hypertrophy
mitosis has ceased and chondrocytes increase in size.
extracellular matrix begins to calcify, trapping chondrocytes in the lacunae
zone of degeneration (calcified) cartilage
chondrocytes degenerate and die secondary to the calcifying extracellular matrix from increase mineralization
zone of ossification
spaces in the walls of the lacunae once occupied by chondrocytes now allow for the invasion of osteogenic cells into the lacunae in addition to vasculature that also invades this zone
what is the diaphysis
bone shaft
what is the diaphysis the location of
primary ossification center with the process of ossification being the same as previously mentioned for the secondary ossification center
what do the growth plates contribute to
the bone’s interstitial growth (or its length)
what happens during appositional bone growth
bone is added to the external surface while bone is removed simultaneously internally, which widens medullary cavity as well as the bone’s overall diameter (its width)
is the first bone of development (or after fracture) unorganized or organized?
unorganized
when is primary bone tissue present
during development of bone or when a fracture is being repaired
what does fracture cause
destruction of bone matrix and death of bone cells
what do damaged blood vessels form
a clot
what are removed from macrophages
the clot, cells and damaged matrix
what do the periosteum and endosteum respond with
intense proliferation, surrounding the fracture and penetrating the fracture
what is the process of bone formation
primary bone is formed as hyaline cartilage is formed, then replaced with bone, as well as connective tissue is formed and replaced.
these form irregular trabeculae or bone calluses
what is the callus replaced by
secondary bone tissue from remodeling
what type of gland is the thyroid gland
butterfly-shaped, bi-lobed endocrine gland located in the next ventral to the lower cervical vertebral column
what are thyroid parafollicular cells responsible for
synthesis and secretion of the peptide hormone calcitonin in response to elevated blood plasma Ca2+ concentration
what does calcitonin do to blood Ca2+ levels
lowers blood Ca2+ levels by inhibition of bone resorption .
ex. inhibition of osteoclast activity
normal function of calcitonin in normal day to day
no real function of calcitonin in normal day-to-day Ca2+ regulation
hypercalcemia
when plasma Ca2+ concentrations are extremely high due to over-secretion of parathyroid hormone by a parathyroid gland tumor (parathyroid adenoma)
what is calcitonin vital in
bone formation
size and location of parathyroid glands
small, paired (superior and inferior) ovoid-shaped endocrine structures on dorsal surface of thyroid
where are chief (principal) cells most numerous and what do they do
most numerous within the parathyroid.
secrete parathyroid hormone (PTH) in response to decreased blood Ca2+ levels (antagonist to calcitonin)
what does PTH act directly/indirectly on
bone
kidneys
gastrointestinal tact
how does PTH increase plasma Ca2+ levels
- increasing Ca2+ resorption from bone via osteoclast activity.
- increasing reabsorption of Ca2+ from kidneys (less Ca2+ excreted in urine).
- activation of an enzyme (1-hydroxylase) in the kidneys that converts Vitamin D (obtained from diet or sunlight and first metabolized in the liver) to calcitriol [1,25-(OH)2D]. calcitriol increases Ca2+ and phosphate absorption from the small intestine into the blood
does PTH increase or decrease bone growth
while PTH has an opposing effect on plasma Ca2+ levels compared to calcitonin, both promote bone growth along with calcitriol
composition of special CT: blood
plasma
buffy coat
formed elements
what are the components of plasma and the approximate fractions for each
Plasma makes up 55% of blood volume.
Water: 91%.
Proteins: 7%.
Salts, sugars, and lipids: 2%.
what is the buffy coat
very thin, grayish layer of white blood cells mostly sandwiched between plasma and formed elements in a centrifuged blood sample
what makes up the formed elements
red (erythrocytes) and white (leukocytes) blood cells along with platelets (thrombocytes)
what is much of the formed element fraction
red blood cells (hematocrit) given the sheer number of these cells compared to platelets and leukocytes
volume of blood in males
5-6 L
volume of blood in females
4-5 L
shape of erythrocytes
biconcave and anuclear
what is hemoglobin comprised of
4 polypeptide (globin) chains with iron-containing heme groups associated with each globin chain
what does O2 bind to in hemoglobin
binds weakly to iron of iron-containing heme group
what does CO2 bind to in hemoglobin
binds to globin
does CO have a higher or lower affinity to the iron-containing heme group than O2
several hundred times greater
what do macrophages do with damaged or old erythrocytes and where
macrophages in the spleen and slightly in the liver digest damaged or old erythrocytes and recycle many components, including much of the hemoglobin molecule.
*excludes heme group without the iron ion which is excreted from the body via the urine and feces as a form of bilirubin + bile
what is erythropoietin (EPO)
hormone secreted by kidneys that drives red blood cell proliferation and differentiation in red bone marrow
what are the types of leukocytes
granulocytes and agranulocytes
structure of granulocytes
multi-lobed
what do granulocytes contain and how are they named
stain different colors.
named based on the histological dye that stains the granules (eosin or hematoxylin)
what are granulocytes comprised of
neutrophils
eosinophils
basophils
structure of agranulocytes
single-lobed
what are agranulocytes comprised of
monocytes/macrophages
lymphocytes
blood cell precursor
hematopoietic stem cell
myeloid stem cell
precursor to progenitors that form all blood cell types except agranular lymphocytes (T and B cells) and natural killer (NK) cell
blood cell types formed by myeloid stem cells
erythrocytes
thrombocytes (platelets)
granulocytic leukocytes (basophils, eosinophils, neutrophils)
agranular monocyte (macrophage precursor)
what formed T and B lymphocytes and NK cells
lymphoid stem cells
3 phases of hemostasis
- smooth muscle spasm
- platelet plug formation
- clotting
is the hemostasis clotting mechanisms complex or simple and what does it involve
very complex process
involves cascade of factors
steps of hemostasis clotting mechanism
- thrombin drives conversion of fibrinogen to fibrin
- fibrin is product in clot formation
- plasmin dissolves the clot
A blood
can accept blood from A and O blood types from a donor
B blood
can accept blood from B and O blood types from a donor
AB blood
can accept blood from A, B, AB and O blood types from a donor
O blood
can only accept O blood
what blood is most common in the population
O+ blood (1/3rd of population)
what type of blood does emergency transfusion typically involve
O blood (centrifuged and washed to remove antibodies) from a donor even though using same blood type is optimal
Rh factor
either positive or negatie
is Rh+ or Rh- most common
Rh+
rarest blood type
AB- (<0.5%)
types of blood cancers
leukemia
lymphoma
myeloma
characteristics of leukemia
originates in bone marrow.
acute and chronic forms.
can be of myeloid or lymphoid origin (WBC).
circulates in blood
characteristics of lymphoma
originates in lymph node (T or B cells).
lymphoid origin.
Hodgkin’s vs. non-Hodgkin’s lymphoma: (+) Reed-Sternberg cells present with Hodgkin’s
characteristics of myeloma
originates in bone marrow.
plasma cell origin.
typically slow-growing
how are cells laid together in epithelia
laid together tightly in sheets - avascular and innervated
what does epithelia line
internal and external surfaces:
- epidermis
- mucous membranes - conjunctiva and oral cavity
- endocrine and exocrine glands
what directionality does epithelia possess
apical/basal/lateral (polarity)
what does epithelial tissue form
boundaries between different environments - nearly all substances must pass through
functions of epithelial tissue
Protection for underlying tissues from radiation, desiccation, toxins, and physical trauma.
Absorption of substances in digestive tract lining with distinct modifications.
Regulation and excretion of chemicals between underlying tissues and body cavity.
Secretion of hormones into blood vascular system.
Detection of sensation
where do the secretion of sweat, mucus, enzymes, and other products that are delivered by ducts come from
glandular epithelium
how are epithelial cells classified
shape:
- squamous (flattened)
- cuboidal (width and length same)
- columnar (elongated vertically)
what can the apical surface of epithelial cells have
cilia or microvilli
what is epithelial tissue classified as
- simple: single layer of cells
- stratified: >1 layer of cells
- pseudostratified: one layer of cells that gives appearance of more than one layer being present in vertical section. simple tissue bc all cells are in contact with basal lamina
how many layers of cells does simple epithelium consist of
single layer
in what type of epithelium does absorption, secretion, and filtration occur
simple epithelium - the thinness of the epithelial barrier facilitates these processes
what contains simple epithelium
lungs
kidneys
mesothelium
endothelium
simple squamous
very thin tissue.
rapid diffusion.
ex:
- alveolus within lung
- bowman’s capsule in kidney
- endothelium within a venule (very small vein)
simple cuboidal
single layer.
central nucleus.
absorption and secretion.
kidney.
ovary.
ex:
- tubules in kidneys
- follicular cells in thyroid
what do simple columnar cells possess
organelle density and energy reserves to engage in the most complex and efficient secretory or absorptive functions
where are simple columnar epithelia with microvilli found
lining the small intestine
where does 90% absorption from the digestive tract occur
small intestine
where are ciliated types of simple columnar found
in small bronchioles of the respiratory tract and in fallopian tubes of female reproductive tract.
cilia aid in the movement of mucous or reproductive cells
what is the unicellular gland or goblet cell
specialized columnar cell of mucous membranes that secretes mucous for protection
locations of simple columnar
stomach.
small intestine.
large intestine.
bronchioles of the lungs.
exocrine ducts and large ducts of kidney
where is pseudostratified epithelia most prevalent
in upper or lower respiratory tract as ciliated types
what do all pseudostratified cells reach / not reach
all cells reach basement membrane but not apical surface
where are non-ciliated pseudostratified epithelium found
in ducts of larger glands or male urethra.
these may be transition zones between epithelial types
what do cilia of respiratory pseudostratified epithelia do to propel mucous along the surfaces of cells
beat in a rhythmic manner –> ciliary escalator
ciliary escaltor
resultant movement of mucous from the lower respiratory tract via ciliary movements
how many layers/surfaces do stratified epithelium have and what are they
multiple layers of epithelial cells.
apical and basal layers, along with apical and basal surfaces for each epithelial cells within the tissue
what are the 2 types of stratified epithelium and where are each found
Stratified squamous keratinized (SSK): epidermis - outer layer of skin.
Stratified squamous non-keratinized (SSNK): mucous membrane tissues - oral cavity, palpebral conjunctiva, corneal epithelium, esophagus, rectum.
difference between SSK and SSNK
apical layers of tissue in SSNK are nucleated unlike SSK.
keratin granules will be seen in mid-layers of tissue in SSK, but not in SSNK.
qualities of stratified cuboidal
glandular epithelium.
two-layered tissue
qualities of stratified columnar
rare in human body - only found in isolated locations (ex. bulbar conjunctiva)
where is transitional found
urinary epithelium - bladder, ureter, portion of urethra
qualities of transitional
ability to stretch: squamous appearance when distended, cuboidal when not.
dome-shaped apical surface of apical layer of cells when not distended.
looks like stratified cuboidal tissue when non-distended, but has more than 2 layers
qualities of H & E stains
Hematoxylin: basic stain that stains acidic structures a purple color.
Eosin: acidic stain that stains basic structures reddish-pink color.
what is the external layer of the basement membrane
basal lamina - consists of outer lamina lucida and inner lamina densa
what does the basement membrane serve as
anchor for hemidesmosomes found in basal cell membrane of basal epithelial cell layer, as well as an anchor to deep, connective tissue
tight junctions (zonula occludens)
later surface nearest apical surface.
anchoring junction
belt junctions (zonula adherens)
overlapping transmembrane proteins.
anchoring junction
gap junctions
utilizes connexons that allow for direct cell-cell communication
desmosomes
overlapping transmembrane proteins anchored into plaques in cell membrane.
anchoring junction
hemidesmosomes
on basal surface of epithelial call and anchors epithelium to underlying basal lamina
types of exocrine glands
merocrine/eccrine
apocrine
holocrine
merocrine/eccrine
most common.
least destructive as secretions
apocrine
part of cell membrane forms vesicle to contain secretant and is lost.
sweat gland sin axillary, groin, breast
holocrine
most destructive to cell as cell membrane ruptures.
meibomian glands of eyelids and sebaceous associated with hair follicles in skin –> lipid-based secretion.
