Histology - Chapter 8

Interneuronsform communicating and integrating network between sensory and motor neurons, 99.9% of all neurons are this.

Perikaryoncell body of a neuron

Axonmost neurons have only one

Mulipolarone axon, 2 or more dendrites, MOTOR AND INTERNEURONS

Bipolarone axon - one dendrite, special senses, retina and CN VIII

Psudeounipolardevelops from bipolar, most are sensory located close to the CNS

Nissl Bodiesribosomal content

Axon hillocklacks organelles

Axonal transportnewly synthesized proteins are transported to distant locations within a neuron, bidireectional, mode of communication

AnteroretrogradeNerve cell body -> periphery, uses kinesin (uses ATP)

Retrogradefrom axon terminal and dendrites -> nerve cell body, mediated by dynein

Nueral stem cellsolfactory bulb and dentate gyrus of hippocampus, able to divide and generate new neurons

Nestinintermediate filament that characterizes neural stem cells - used to ID them

Golgi type 1skeletal muscle, travel more than a meter

Golgi type 2interneurons, have very short axons

Symptoms of Parkinsons:1. resting tremor

2. rigidity

3. increased tone

4. slowness of movement (bradykinesia)

5. lack of spontaneous movement

6. slurred speech

7. loss of postural movement

Secondary parkinsons caused by?toxins and infection

Parkinsons histologic findings:Gliosis (increase in the number of glial cells), loss of pigmentation, and Lewry bodies (characteristic inclusions)

Synapsesare not histologically resolvable

Electricl synapsescontain gap junctions and allow movement of ions - the spread of electrical current

SNAREsv-SNARE (vesicle-bound) and t-SNARE (target membrane bound)

Synaptotagmin-1replaces the SNARE complex (SNARE dismantled and recycled by SNAP25/NSF)

Presynaptic densitiesproteins on cytoplasmic side of the presynaptic membrane, ACTIVE zone

Rab-GTPase, t-SNARE, and synaptotagmin binding proteinActive zones are rich in these

Postsynaptic densityinterlinked proteins that serve numerous functions

Porocytosissecretion of NT w/o vesicle fusion, vesicles anchored at active zones release NT through transient pore

Transmitter gated channelspost synaptic membrane - bind and change conformation

Curarepoison tip arrow, bind to NA+ channels and blocks action of Nicotinic = muscle paralysis

Atropinbelladona, blocks action of muscarinic rececptors

Clostridium botulismblocks ACH release

Chromaffin cellsalso release E into the blood stream (found in adrenal medulla)

Na+ dependent transportersaction of catecholamines terminated by use of these (cocaine and amphetamine block reuptake, lasts longer in synapse)

COMT and MAOdegrade catecholamines - MAO found in outer mitochondria membrane

AChE inhibitorsused for the treatment of Lambert-Eaton, Myasthenia Gravis, glaucoma, and Alzheimers Disease

Slow transportONLY ANTEROGRADE

Fast transportboth directions, therefore antero and retrograde

Retrograde transportis used by viruses and infection, carries to the cell body

Mullers CellsRetina (peripheral neuroglia)

Schwann cellsdevelop from NC and differeniate via Sox-10

Abaxonal Plasma Membraneshwann cell exposed to endoneurium

Adaxonal periaxonal plamsadirect contact with axon

Mesaxonaxon is completely enclosed by the schwann cell

Guillan-Barre syndrome (PNS)common life-threatening disease of the PNS, MS damaged, axons exposed to ECM - paralysis, loss of muscle coordination, loss of sense

Multiple Sclerosis (MS) - CNS Diseaseattacks myelin in CNS, destroy oligodendrocytes, MBP is major target, white matter plaques - neuro deficits, unilatera vision issues

Neureglin (Ngr1)Myelin sheath thickness is regulated by this growth factor that workds on schwann cells

Schmidt-Lanterman Cleftsmall islands within successive lamellae of the myelin

AstrocytesLargest - physical and metabolic support, protoplasmic - outer covering of gray matter, fibrous - inner core of white matter

Tumors from fibrous80% of all brain tumors, identified via GFAP

Glia limitansBBB, protoplasmic astrocytes extend processes to basal lamina of pia mater to form this barrier around CNS

Oligodendrocytes (CNS)maintain myelin sheath on many axons

Myelin of CNSPLP, MOG, Omgp

Myelin of PNSPo and PMP-22

Microglia Phagocytic cells - remove bacteria, microorganisms, play critical defensive role

Epindymal cellsform epithelium like lining of the fluid filled cavities of the CNS, histologically - basal cell surface interdigitates with astrocyte processes

Choroid Plexusmodified ependymal and associated capillaries

Histology - Chapter 12

Ground Substanceother matrix of non-collagenous proteins, only 10% of bone

Collagens?Type 1 (mostly) and some Type 4

Proteoglycan Macrmoleculescontain glycosaminoglycans - contribute to compressive strength of bone

Mutliadhesive glycoproteinsattach bone cells and collagen to ground substance (= glue b/n collagen and hydroxyapatite)

osteonectin - glue b/n collagen and hydroxyapatite

osteopontin - attach bone cells to matrix

sialoprotein 1 and 2 - mediate cell attachment and initiate Ca2+ phosphate formation during mineralization

Osteocalin captures calcium from circulation and stimulate OC remodel

Protein Sassists in the removal of cells undergoing apoptosis

MGPdevelopment of vascular calcifications

BMPs (bone morphogenic proteins)induce differentiation of mesenchymal cells -> osteoblasts

OP-1recombinant human BMP-7 used clincially to induce bone growth post-op

Lacunaecontain bone cells (osteocyte)

Canaliculiosteocytes extend numerous processes into these tunnels - connect lacunae

Osteoprogenitorarise from mesenchyme -> OB, enlongated nuclei

OsteocyteOB completely surrounded by ECM that it secreted

Bone-lining cellsremain on bone surface when no active growth (come from OB), thought to function in nutirtion and support of osteocytes

Osteoclastsbone resorption cells that are present on bone surface

Trabeculaespongelike network consisting of thin anastomosing spicules of bone tissue)

Compact boneDense layer outside

Long boneslonger in one direction (tibia, metacarpals)

Short bonesequal in length and diameter (carpal bones)

Flat bonesthin and platelike (skull and sternum) - contains layer of spongy bone b/n two dense layers of compact

Irregular bonesdon't fit into any category, complex structure - vertebra, or may contain air/sinus - ethmoid bone

Sharpey's fibersextend into the bone, continuous with the collagen in ECM

Periosteumfibrous outer layer that resembles dense CT and inner layer with osteoprogenitor cells

Aricular Cartilagehylaine cartilage

Endosteumone-cell think layer that lines bone cavities, w/ osteoprogenitor cells

Arthritisinflammation of the joints -> degrees of pain

Ankylosisdamged cartilage that calcifies and is replaced by bone

Rhematoid ArthritisImmune response mediated damage to articular cartilage

TuberculosisInfectious response mediated damage to articular cartilage

Gouty Arthritisdeposition of uric acid crystals, common side effect of thiazide diruetics

Haversian canalcontains the vascular and nerve supply

Osteonconcentric lamellae + haversian canal

Interstital lamallaeremnants of previous concentric lamallae

Volkmanns canalchannels in lamallar bone that allow A/V/N from periosteum and endosteum to reach osteonal canal - NOT surrounded by concentric

Nutrient foraminamost likely found in diaphyses and epiphyses

Immature boneno concentric, more cells than mature, randomly arranged, more ground substance, not heavily mineralized (found in mouth, orthodontic)

CBFA1triggers differentiation of osteoprogenitor cells -> OB

ALP and osteocalinused a clinical markers for osteoblast activity

Matrix vesiclescontain ALP and are secreted only during the period where cells produce bone matrix

Osteocytic Osteolysisdegradation of bone by MMPs (maintains that resorptive nature of osteocytes deals with ca2+ homeostasis, not remodelling)

Howship's Lacunaresorption bay created by OC activity on the bone surface

TRAPused clinically as a marker of OC activity and differentiation

Osteoclastlarge size and marked acidophilia, strong histochemical reaction for acid phosphatase

GMP, CFU-GMwhat osteoclasts are derived from

c-fos and NFBosteoclast precursors express these transcription factors

RANKlater, is produced and expressed

RANK-RANKL signaling essential for OC differentiation and maturation

Inflammatory Reactioninflammation can cause T-lymphos to express RANKL - inflam processes can stimulate OC-mediated bone resorption

OPG can block RANK-RANKL, it is a decoy -> lack of available RANKL, produced by OB

Ruffled borderpart of the OC that is in direct contact with bone

Clear zone (sealing zone)ringlike perimeter of cytoplasm near the ruffled border that demarcates the bone area being resorbed

EC matrix adhesion moleculesprovide tight seal b/n plasma membrane and mineralized matrix of bone, use integrins

Basolateral regionexocytosis of digested material, vesicles fuse here to release their contents - use TRAP

Cathepsin K and MMPshydrolytic enzymes that degrade collagen and other proteins in the bone matrix

Decalcify before Digestcarbonic anhydrase II -> H2CO3 -> HCO3 and H+ ->ATP proton pump (H+ thru ruffled) -> into resorption bay

Chief cells of the Parathyroidsecrete PTH

Parafollicular Cells of the Thyroidsecrete calcitonin