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176 Cards in this Set

  • Front
  • Back
name divisions of nervous system
Central--spinal cord and brain
Peripheral--sensory elements that conduct info to CNS and motor elements from CNS to muscle cells
describe system pathway
from autonomic/somatic to PNS to CNS back to PNS in the form of motor output to either the somatic or autonomic nervous system.

autonomic has two divisions: sympathetic (controls fight or flight) and parasympathetic (involuntary actions).

somatic controls voluntary skeletal muscle movements
parts of the neuron
cell body
dendrites
one axon
synaptic terminals w/presynaptic and post-synaptic domains
where does communication btwn the neurons occur?
at the synapse. information is received by the dendrites and passed along by the cell body/axons
which part is presynaptic? post-synaptic?
pre--part where axon contacts other cell
post--spines of dendrites
name/describe 3 types of neurons
bipolar--one axon, one dendrite
pseudounipolar--one axon, 2 dendrites (brain and spinal cord)
multipolar--one axon, many dendrites (most common)
how do axons change voltage potential?
graded voltage change--at the cell body that spreads passively and declines with distance
action potential--all or nothing response propagated through the axon
how do anesthetics work?
block Na+ receptors of sodium ion channels which some neurons use. blocks action potential along axon.
most important organelle in neuron?
cytoskeleton--maintains long processes/shape of cell
why do certain stains color the cell body but not the axons?
stains like nissl blue stain the cell body because there are a lot of ribosomes. do not stain the axons because there are no ribosomes there
how do axons get protein if all ribosomes are in the cell body?
via ribosomal/axonal transport. via microtubules! very important--if disrupted or dysfunctional, the entire neuron will degrade (ex. huntington's disease)
how do viruses invade cell body?
hitch a ride via axonal transport and can spread to other neurons.
name types of glial cells/functions.
Peripheral
1. satellite cells--support
2. schwann cells--form myelin sheaths

Central
3. ogliodentrocytes--form myelin sheaths
4. astrocytes--form blood-brain barrier
5. microglia--scavengers
6. ependymal--barriers btwn. compartments
why is myelin so important?
myelin speeds up action potential as it jumps from sheath to sheath, separated only by small nodes of ranvier. nodes efficiently regulate ion movements as well.
what is myelin comprised of/how is it formed?
mostly comprised of lipids. have some proteins, which are essential to the myelin formation process in which the cytoplasm is extruded form the region of the internode.
what is the function of the blood brain barrier?
formed by endothelial cells held together by tight junctions with astrocytes. helps determine interstitial fluid composition by restricting ionic and fluid movements between brain/blood. astrocytes line the vessels and provide communication.

most proteins, etc must be actively shuttled through the endothelium.
what are the functions of an astrocyte?
provide communication from blood vessels to neurons. provide neurons with energy in the form of lactate. (prefer lactate over glucose).

they take out excess Na+, and terminate action so it doesn't continue too long.
how are astrocytes linked?
via gap junctions (connexins)
in what form are axons in the PNS? how do supporting cells play a role?
axons are usually found in bundles. supporting cells are schwann cells (create myelin and ensheath nerve fibers) and satellite cells (surround nerve cell bodies and provide trophic support)
outline structure of a peripheral nerve
individual axons are surrounded by endoneurium

the axons are bundled together and surrounded by a perineurium to form a fascicle

fascicles are bundled together and surrounded by the epineurium
are non-myelinated axons surrounded by schwann cells?
yes, they just dont produce myelin.
what does the spinal cord consist of?
white (outer layer) matter and gray (inner layer) matter.
name three types of muscles
1. skeletel
2. cardiac
3. smooth
describe the development of skeletal muscle
development is anterior to posterior. the mesoderm forms somites, then the ventral side degrades to eventually become the dermamyotome which forms the skeletal muscle
what are the characteristics of skeletal muscle?
striated due to arrangements of think and thin filaments.
describe the commitment cycle of a skeletal muscle cell
precursor to myoblast which is fused via integrins to form the myotube, which also requires integrins to assemble sarcomeres/muscle fibers
why are contractile proteins made in the muscle cells and not in the spleen?
although all somatic cells have the same DNA, muscle protein genes for example are transcribed in muscle cells by transcription factors (trans-activators) that dictate "a muscle cell will be a muscle cell"
what purpose does MyoD serve in skeletal muscle?
it is a trans-activator protein (there are many) that binds to regulatory regions of genes in muscle cells to help transcription. it has a helix loop helix formation
features of skeletal muscle cells?
nuclei pushed to the side. forms striated pattern.

provide strong, quick voluntary actions
features of cardiac muscle cells?
nuclei centrally located. have intercalated disks that hold the muscle striations together.

involuntary, quick actions
features of smooth muscle?
look like squamous epithelium. nuclei centrally located. are fat in the middle then ends are closely packed. not striated

weak, slow involuntary action
how does connective tissue interconnect with skeletal muscle?
endomysium--surrounds individual myofibrils
fascicle--myofibrils are are bunched together in fascicles and surrounded by perimysium
epimysium--fascicles are bunched together and surrounded by epimysium.
how do you recognize A, Z and I bands histologically?
A=dark band
Z=lighter band
I=thin dark band between Z bands
what is a sarcolemma?
it is the plasma membrane and the lamina surrounding bundles of myofibrils (different from endomysium--endomysium is around the sarcolemma). nuclei are at the periphery.
what is one muscle fiber comprised of?
one myofiber is composed of individual myofibrils which are composed of myofilaments.
where is glycogen stored/what is it?
stored in the cytoplasm and is the source of energy for contracting muscles by anaerobic glycolysis.
what is a sarcomere?
one unit of muscle--repeating in myofibrils. goes from Z line to Z line.
what are thin and thick filaments?
they are the myofilaments actin (thin) and myosin (thick).
A band? I band? M band?
A band=thick and thin filaments crossing each other
I band=only thin filaments
M band=center line down middle of sarcomere--cuts it in half
molecular structure of myosin.
myosin is comprised of a myosin filament with globular heads that stick out to interact with actin and also hold ATPase.

comprised of heavy chains in the tail and light chains in the head.

there is a hinge, which separates the tail from the head and allows the head to stick out to interact.

they are arranged head to tail, which accounts for the lighter H band within the A band. no heads in the H band.
What is actin comprised of?
G actin polymerized to form F actin in dark and light chains.
How does tropomyosin affect muscle contractions.
Tropomyosin lays on top of actin filaments , blocking myosin head binding sites so contraction doesn't happen all the time.
How does troop in relate to tropomyosin?
Sometimes we want the muscle to contract so troponin is bound to tropomyosin in three components:

1. TnT--binds to tropomyosin
2. TnI--inhibits myosin binding
3. TnC--binds calcium. When Ca is released in muscle contraction, it binds to the TnC and causes a conformational change in tropomyosin which allows myosin to interact with actin causing muscle contraction.
How are thick filaments anchored within a sarcomere?
Anchored by Titin emanating from the Z line and meeting in the center near the M line. Makes sure myosin doesn't overstretch or break.
How are thin filaments anchored in a sarcomere?
Anchored by nebulin and alpha actinin.

Nebulin is a smaller version of Titin which binds bundles of actin filaments to the Z line.

Alpha actinin is along the Z line and helps to bind actin to the Z line.
What is the neuromuscular junction? Aka motor end plate.
Where the axon makes contact with the muscle fiber. There are junctional folds at this contact area to increase surface area for the reception of AcH proteins.
How does myesthenia gravis work?
Causes Ntibodies to bind to AcH receptor sites blocking binding of the AcH and causing generalized muscle weakness and ptosis.
Steps of AcH release.
AcH is released.
AcH binds to receptors in muscle cell sarcolemma.
The membrane becomes permeable to Na+ ions and the muscle membrane depolarizes.
This depolarization is transferred via the T-tubule system.
AcH is degraded by AcH esterase.
What happens when AcH is not degraded?
Muscle will continue to stay depolarizes and the muscle will continue to contract.
What is the triad?
Consists of a T-tubule sandwiched between the smooth endoplasmic reticulum.
What is a t tubule?
The invagination of the sarcolemma which conducts action potential across the muscle by Interacting with smooth ER. After depolarization the gated calcium channels in the SER are opened.
How do myosin heads interact with actin chains?
After Ca is released the myosin head binds to actin. ATP then binds to the myosin head causing a conformational change of actin binding site and myosin releases. ATP is hydrolyzed and myosin head bends forward. The myosin binds to this new site and the process repeats as myosin hops along the actin chain.
Which band in a sarcomere never changes length? Which does?
A band doesn't change. I band can stretch or compress.
What types of muscle can repair? How?
Skeletal can repair. Cardiac cannot. Repaired by satellite cells which are basically adult stem cells which can differentiate and divide.
What are extrafusal fibers?
Just a different name for muscle fibers
What are intrafusal fibers? Name the 2 types and their function.
They are specialized muscle cells of two types.

Bag fibers--communicate with the muscle and the CNS
Chain fibers
What is the neuromuscular spindle?
It sits on the muscle fiber and consists of the intrafusal fibers. It senses stretch and communicates with the CNS via efferent fibers (to) and afferent fibers (from).
Which family of proteins regulates muscle repair via satellite cells And muscle cell differentiation?
MyoD family.
how is cardiac muscle arranged and how can you differentiate it from skeletal muscle?
myocytes are arranged into fascicles.

they have centrally located nuclei and intercalated disks and are branching cells--easy to tell on longitudinal section
how are cardiac cells connected?
via gap junctions which are part of the intercalated disks--they conduct the electro-chemical impulse through all the cells allowing the heart to beat.
parts of intercalated disks?
1. fascia adherens--attach actin to the Z line
2. desmosome--spot weld at the Z line
3. gap junctions--couples cardiac cells (MOST IMPORTANT)
what are the differences in the T-tubule system for cardiac muscle?
cardiac muscle has a diad not a triad. also it is located at the Z line instead of the I-band
what is special about the smooth muscle?
no M line, myosin heads are present along entire chain (not stacked end to end), which allows smooth muscle to stay contracted indefinitely.
consistency and composition of cartilage
consistency=gel
composition= organic only, no inorganic component

ORGANIC:
collagen (40%--type II)
proteoglycans (60%)
consistency and composition of bone
consistency=rigid
composition=
ORGANIC (50%):
Collagen (90%--type I)
Proteins (10%)

INORGANIC (50%):
Calcium Phosphate Crystals
name 3 types of cartilage.
1. hyaline--most abundant
2. elastic--similar to hyaline, very bendable (least abundant)
3. fibrocartilage-resists compressive forces
functions of cartilage (4)
1. support
2. shock absorption, compression resistance
3. smooth sliding surfaces
4. framework for development and growth of bone
name of a cartilage cell.
chondrocyte
name of transcription factor for chondrocytes
SOX9, drives differentiation
features of a chondrocyte
huge RER and lots of secretory vessels because it produces a lot of proteins.
what is the ECM of a chondrocyte composed of?
hyaluronic acid covalently linked to type II collagen and lots of water/proteoglycans
features/special characteristics of cartilage.
it is avascular!
gets nutrients from the ECM, which limits its growth and repair.
don't require lots of oxygen!
what is the perichondrium?
type of irregular dense connective tissue that surrounds cartilage and progresses from mostly collagen fibers to full on chondrocytes.
name the 2 ways chondrocyte growth occurs.
1. appositionally--from the outside, meaning from the perichondrium
2. interstitially--from within, but it is limited.
what is the territorial matrix and why does it stain more intensely?
territorial matrix is the area surrounding newly formed lacunae/chondrocytes.

stains intensely because it has a higher concentration of GAGs.
how does cartilage receive nutrients since it avascular?
from the perichondrium, which is vascularized.
what are isogenous groups?
when chondrocytes form, their lacunae group together in rings sometimes.
characteristics of hyaline.
1. made up mostly of type II collagen ad GAGs.
2. can grow appositionally or interstitially.
3. has perichondrium
characteristics of elastic cartilage,
1. type II collagen, but mostly elastic fibers.
2. can grow both interstitially and appositionally.
3. has perichondrium
characteristics of fibrocartilage.
1. type I collagen (looks like dense irregular CT with chondrocytes)
2. only interstitial growth because it lacks a perichondrium
what is articular cartilage?
a specialized form of hyaline that covers articular surfaces of bones and has no perichondrium.
2 types of bone?
1. spongy, cancellous, or trabeculous.
2. compact
what are the parts of the long bone?
1. epiphysis--the ends of the bone, inner layer is spongy
2. metaphysis--under the growth plate, made of compact bone on the outside and spongy bone on the inside.
3. Diaphysis--the shaft, made of compact bone
4. Medullary--the inner marrow cavity
what are the layers that cover the outer bone and marrow cavity called?
1. periosteum=covers outer layer of bone, made of CT
2. endosteum=covers marrow cavity, made of CT
what are the two layers of the periosteum?
outer later is the fibrous layer, which contains fibroblasts.

the inner layer contains osteoprogenitor cells (meaning precursors to osteoblasts)
does the periosteum cover the entire outer surface of bones?
in long bones, the epiphysis is covered by articular cartilage. it covers any areas of bones that experience articulation/movement.
what are osteons?
aka haversian systems.

they comprise the inner aspect of compact bone and are arranged in circular lamellae (made up of collagen running perpendicular to each other). the middle of an osteon has a haversian canal, which houses a blood vessel/capillary. these blood vessels can also run perpendicular to the haversian systems, and are referred to as Volkmann's canals.
what are the structures inside the lacunae of osteons?
osteocytes, which have many processes called cannuliculi that protrude out and communicate with other parts of the bone via gap junctions between other osteocytes.
describe the appearance of spongy bone?
lots of marrow, with interdigitating pieces of trabecular bone. looks wavy/fluid
what is an osteoblast?
the cells that actually produce bone matrix, and eventually become osteocytes once they are encased in a lacunae.

they are derived from osteoprogenitor cells.
what do osteoblasts resemble?
they resemble fibroblasts in that they appear plumped when they are activated, and thin when not.
what is osteoid?
it is the most recently synthesized bone that has not yet been mineralized (CaPO4).
what are osteoblasts called when they are inactivated?
called bone lining cells and appear flat.
describe the appearance of an osteoclast.
large, multi nucleated cells, on bone surface that are motile. responsible for bone reabsorption.
what are the characteristics/parts of an osteoclast?
they have a ruffle border, which increases the surface area involved in bone reabsorption.

most significant is the "clear zone", which is the area that is directly attached to the bone and sealed off from the rest of the cell/outer cell. the osteoclast is highly acidic, so the clear zone is especially important to prevent leakage of the acidic aspects.

also has an H+ pump, which regulates the acidity.
how does the body know when to break down bone and when to build it?
when osteoclasts break down bone, they release growth factors which initiate osteoblasts to form bone.
what are the proteins and ligands involved in osteoclast formation?
osteoblasts actually regulate the formation of osteoclasts from monocytes through the use of

RANK
RANKL (the ligand)
M-CSF (a stimulating factor produced by osteoblasts)
from what are osteoclasts derived from? what does it require?
osteoclasts are derived from mesenchymal cells-->osteoblast lineage-->monocyte/macrophage lineage

they require CBFA1/RUNX2.

Note: chondrocytes require SOX9!
how does exercise lead to strong bones?
it increases the deposition of mineral salts and production of collagen fibers.

conversely, inactivity leads to demineralization and osteoporosis.
what happens as a result of inadequate mineralization?
the osteoid is not mineralized properly and is thickened. this can lead to rickets.
why is CBFA1 so important?
in studies, mutations or knock out of the gene caused fetus death because bones did not grow and were not mineralized. osteoblasts and osteoclasts were not formed.

mutations in this gene can lead to debilitating skeletal deformations.
what are the two process by which bone is formed?
1. intramembranous--bone tissue formed directly in connective tissue
2. endochondral--formed from a hyaline cartilage matrix.
how does intramembranous ossification occur?
in a vascularized matrix consisting of CT and mesenchymal cells, the mesenchymal cells begin to differentiate to produce osteoblasts (CBFA1)

osteoblasts begin making small "spicules" of bone and adding to it, enlarging it and following the shape of the capillaries.

osteoclasts come in and start working.

osteoblasts eventually become osteocytes.

bone formation continues to occur from the outside, forming lacunae around blood vessels.
how does endochondral bone formation occur?
endochondral is when bone is laid on top of an existing hyaline cartilage matrix.
what is a bone collar?
when cartilage enters proliferation zone and dies within its lacunae, surrounding bone area becomes weak, so osteoblasts within the periosteum begin fortifying the outside with new bone (aka the bone collar)
what is a center of ossification?
as bone begins to form on top of cartilage, blood vessels insert and become centers around which osteoid is calcified.
once bone is mostly matured, where can cartilage be found?
while still growing, cartilage can be found in the growth plates, but once growth is finished, articular cartilage can be found where bones are joined together.
what are the zones of bone growth?
1. resting zone--osteocytes aren't doing anything.
2. proliferation zone--ostoecytes forming rapidly
2. hypertrophic zone--osteocytes growing larger within lacunae
3. ossification zone--osteoblasts forming bone/becoming mineralized once osteocytes die off and leave lacunae empty.
name the stages of fracture repair
Inflammatory
Repair
Remodeling
name the stages of fracture repair
Inflammatory
Repair
Remodeling
what is blood?
blood is a specialized fluid CONNECTIVE TISSUE
what are some of the key functions of blood?
1. transport 02, hormones, nutrients to cells
2. transport CO2 away from tissues
3. protect body against invasion
4. coagulation
5. maintain osmotic balance.
what are the 2 main constituents of blood and what are they made up of?
1. plasma (55%)--92% water, meaning that about 50% of total blood is water.
2. Formed elements (45%)
what are the three categories of formed elements and their breakdowns.
1. leukocytes
-Granulocytes
-Agranulocytes
2. erythrocytes
3. platelets
Name the granulocytes
part of leukocyte family.
1. Neutrophils
2. Eosinophils
3. Basophils
Name the Agranulocytes
part of leukocyte family
1. Lymphocytes
2. Monocytes
name the proteins in the plasma and their general functions
1. albumin--carriers for hormones and drugs, maintains osmotic pressure
2. globulins-carriers for hormones and drugs, maintains osmotic pressure
3. fibrinogen--cleaved to become fibrin in clot formation
of the formed elements, rank their abundance within blood
1. erythrocytes (4-5mil)
2. Platelets (200-400K)
3. leukocytes (6-9K)
what is significant about the size of an erythrocyte?
size=7-8 pico meters

this is significant because most RBCs have the same general size and are used to measure the size of other elements in the blood
name characteristics of RBCs
1. anucleate
2. non-motile
3. biconcave discs
4. reddish
what is the difference between plasma and serum?
plasma is what contains fibrinogen, albumin, and globulins, whereas serum does not contain fibrinogen.

when collecting hematocrit samples, plasma has firbinogen because it is treated with anticoagulant, whereas serum samples are left to coagulate on their own and therefore fibrinogen is converted to fibrin.
what is a reticulocyte?
an immature blood cell which contains polyribosomes.
what is siginificant about the shape of RBCs?
biconcave disc allows for more surface area, and also allows it to bend to fit through capillaries which are smaller than the actual size of an RBC.
what is the structure of hemoglobin?
it is a quaternary structure with 2 alpha and 2 beta chains to which heme is attached.
where are RBCs degraded?
in the liver, spleen and bone marrow and sometimes by macrophages.
How do blood groups work?
They are classified by surface antigens, meaning a person with Type A blood has Type A surface antigens, but Type B antibodies. If they are given Type B blood, it will have Type A antibodies, which will attack the Type A antigens.
Why is the shape of sickle celled RBCs so debilitating? How does sickle cell occur?
They are sickle shaped, are poorer carriers of O2 and adhere easily to the endothelium lining blood vessels so they tend to pile up.

Sickle cell occurs due to a point mutation which causes hemoglobin to unfold and lose its quaternary structure.
Describe characteristics of a neutrophil histologically.
it is a granulocyte

3-5 lobed nucleus that is continuous
granules stained neutral.
may have a "drumstick" on one of the nuclei, indicating a female X chromosome.
functions of the neutrophil.
are phagocytes so they degrade foreign substances.

are the first line of defense because they are the most abundant leukocyte.

can cause fevers due to release of interleukin 1

they are motile in tissues, but to not reenter the blood stream once they leave.

some wander through the blood stream, and some are resting near the endothelium until needed.
Describe characteristics of a eosinophil histologically.
it is a leukocyte--granulocyte.

is acidophilic, so granules stain red.

has a bi-lobed nucleus that looks like a pair of lungs.
function of an eosinophil.
plays a role in allergic reactions and in defense against parasites.

has MBP (major basic protein) which disrupts parasite membranes and causes basophils to release histamine. also has a protein to neutralize heparin.
Describe characteristics of a basophil histologically.
it is a leukocyte--granulocyte

granules are basophilic, so they stain blue.

usually can't see nucleus because so many granules obscure it.
function of basophils.
respond to allergic reaction
release histamine
causes vasodilatation so there is increased membrane permeability.
Describe characteristics of lymphocytes histologically.
leukocyte--agranulocyte

have a large nucleus that takes up most of the cytoplasm.
function of lymphocytes.
There are 3 types of lymphocytes: B, T, and NK (natural killer)

B become plasma cells, producing antibodies

T are "trained" in the thymus

NK kill tumor/infected cells.

**lymphocytes can leave the blood stream and return at will
Describe characteristics of monocytes histologically.
leukocyte--agranulocyte

nucleus off to the side, kidney bean shaped.

predecessor to the macrophage. monocytes enter the blood stream and become macrophage.
function of a macrophage
eat aged, dead, tumor cells and repress antigens.
Describe characteristics of platelets histologically.
small, flat shape. cell fragments, no nucleus.

filled with granules of 2 types:
1. alpha: contain fibrinogen
2. dense: contain calcium, ATP
functions of a platelet.
clot formation, survey for breaks/tears. secrete stimulating factors.

platelets adhere to exposed collagen and become sticky/change shape to block up the wound.
how are platelets formed?
they are derived from megakaryocytes that reside in bone marrow.

the megaK duplicates genetic material without dividing the cell several times resulting in lots of DNA in a huge cell. The cytoplasm produces many granules (platelets). The megaK (non-motile) then sheds the platelets into the blood stream and then dies.
difference between bone marrow in adults and newborns?
newborns=red marrow because it's full of blood and blood forming cells.

adults=red cells replaced by yellow marrow due to increased fat cells.
functions of bone marrow?
1. store RBCs.
2. develop and release new blood cells
3. destroy old RBCs
4. store iron
where does blood cell formation occur?
extra-vascularly, meaning not in the blood. occurs in the spaces between sinusoids (capillaries)
what does bone marrow consist of?
1. stroma (CT)
2. fat cells
3. blood cells
4. sinusoids (capillaries)
what does the stroma of bone marrow consist of?
various collagens
hemonectin
reticular fibers
proteoglycans
ground substance
what is so special about the blood vessels in bone marrow?
they are lined by discontinuous epithelium and they rest on an incomplete basal lamina, which allows RBCs to diffuse into the bloodstream.
name the stages of myeloid hematopoiesis?
1. pluripotent stem cells, which are self renewing and can become any blood cell
2. progenitor cells--partially differentiated, but can also self-renew
3. precursor cells/blasts--fully differentiated or committed to their cell type
4. immature cells
5. mature cells.
which is the only cell that is not part of the myeloid lineage?
lymphocytes which come from lymphoid stem cells.
what happens before cells become mature? important note!
mitosis stops, meaning all blood cells are terminal and cannot divide. must come from stem cells.
which hormone drives RBC development? where is it produced?
erythropoeitin, produced in the kidney.
name/describe the steps in RBC development.
1. pro-erythroblast--large nucleus with prominent nucleoli and lots of RNA because it's making a lot of ribosomes.

2. basophilic erythroblast--lost of ribosomes, so cytoplasm appears very blue (basophilic)

3. polychromatophilic erythroblast--cytoplasm is blue and red because it has ribosomes and hemoglobin. still mitotis.

4. orthochromatic erythroblast--post mitotic. cytoplasm is full of hemoglobin so it is acidophilic and appears red. nucleus is full of heterochromatin.

5. reticulocyte--cell ejects the nucleus (pyknotic cell)

6. mature red blood cell with no nucleus.

**throughout development of RBCs, cell gets smaller, and nucleus gets smaller/condenses
name/describe the steps in granulocyte development.
1. myeloblast--cannot differentiate between it and pro erythroblast.
2. promyelocyte--has azure granules.
3. myelocyte--has azure+specific granules (active nucleus)
4. metamyeloctye--nucleus indents. cell has many specific granules, few azure granules. (inactive nucleus)
what are azure granules and which blood cells have them?
azure granules are lysosomes and all granulocytes have them, along with specific granules.
how many platelets per megakaryocyte?
1-2K
name the 4 types of staining and describe their differences.
1. histology--used to highlight chemical composition
2. histochemistry--used to highlight specific enzymes
3. immunostaining--highlights antigens
4. in situ hybridisation-- highlights mRNA sequences
describe advantages/disadvantages of fixing and freezing.
fixing=preserve structure at the expense of function, which is better for mRNA sequences

freezing=preserves function at the expense of structure, which is better for histochemistry and immunostaining.
how can we use the three types of staining to classify types of muscle fibers?
1. histochemical--highlights the myosin ATPase enzyme in muscle to determine which are slow/fast
2. immunostaining--uses immunoflourescence to highlight diff. types
3. in situ--uses radioactive probes
what are the three types of skeletal muscle fibers and how are they arranged?
3 types are organized into motor units:

1. Type I--slow, don't fatigue
2. Type IIA--fast, fatigue slowly
3. Type IIX--fast, fatigue quickly

muscle fibers are recruited in order of fatigue. Type I first, then Type IIA, then Type IIX
what does specificity v. sensitivity mean in staining?
specificity means it will only stain the parts you want it to stain. sensitivity means it will only stain specific epitopes in antigens
what does the conducting portion of the respiratory system consist of?
nose
nasopharynx
larynx
trachea
bronchi
bronchioles
what does the respiratory portion of the respiratory system consist of?
respiratory bronchioles
alveolar ducts
alveolar sacs
alveoli
what's the difference between the respiratory bronchioles and conducting bronchioles?
the beginning of alveolar indents/sacs
what does the pleura consist of?
1. parietal pleura--attached to rib cage and helps lungs expand (made of elastic and collagen fibers)
2. pleural fluid
3. visceral pleura--attached to lungs (made of elastic and collagen fibers)
describe the epithelium most commonly assoc. with the respiratory system.
pseudo-stratified columnar with cilia and goblet cells.
what is squamous metaplasia?
it is the result of excessive drying of the mucosa (from smoking) and causes a change in the epithelial layer. it does from pseudostratified to squamous epithelia.
what are the conchae and how do they relate to smell?
they are part of the nasal cavity, and they slow down air coming in and are lined by microvilli.

the topmost conchae is lined with olfactory epithelium (only on top), which is responsible for smell.

the other conchae are lined with typical respiratory epithelium.
describe the characteristics of the olfactory epithelium.
made up of bipolar neurons with stereo cilia and axons that bundle to form the olfactory nerve.

there are sustanticular cells for support (thin and at top of layer)

also basal cells which can differentiate and repopulate the epithelium.

also serous glands which produce thin watery secretions.
describe the parts of the larynx.
false vocal chords have glands that produce a serous fluid to lubricate the true vocal chords.

when the true vocal chords open, the air moving through the space is what produces the sound.
what are the hallmark features of the trachea?
a c shaped ring made of hyaline cartilage, a perichondrium, serous mucous glands, CT, and respiratory epithelium.

where the C is broken, it is filled with smooth muscle to prevent the esophagus from coming into contact with hard cartilage when you swallow.
what are the features of the intrapulmonary bronchus?
they are varying in diameter and surrounded by alveoli.

they have plates of cartilage, not in Cs like in trachea. have goblet cells, smooth muscle, resp. epithelium.
what are the features of the bronchioles?
the epithelium starts to transition from pseudo strat. to squamous epithelium

there are cilia, but goblet cells are replaced by clara cells which produce a watery substance.

there's no cartilage or glands, but there is smooth muscle.
features of the alveoli?
made of 3 types of squamous epithelium:

1. endothelium
2. thin type I
3. chunky type II
how does air diffuse through these types of epithelium?
the type I cell's basal lamina is fused to the basal lamina of the endothelial cell, making the barrier very thin.
what is the function of a type II alveolar cell?
produces surfactant and lowers surface tension so alveloli don't stick together.
what does a person with emphysema's alveoli look like?
there are tons of empty spaces because elastic fibers are destroyed
what is wrong with people who have cystic fibrosis?
their chloride channel is defective so mucous builds up and becomes thick, trapping bacteria and causing many problems. cilia can't compensate for broken chloride channel.