Exam 3 Flashcards
(201 cards)
1
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Neurochemistry
A
Study of neurochemicals, influencing the function of neurons and the regulation of the networks they form
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Current Dogma of neuron comunication
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Neurons communicate with each other through contiguous connections
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Biological challenges of Neurons
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Extend long processes, conduct signals over long distances, convey information in a polarized unidirectional manner (sensory to motor)
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Glial cell current dogma
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actively contribute to neuronal signaling and health 1:1 glial cells to neurons in brain
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Macroglia and microglia
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specialized macrophages (from HSC) for phagoscytosis (microglia), proliferate when the brain is damaged, immune and inflammation response, secrete gliotransmitters in response to the environment
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Macroglia
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Derived from ectodermal tissue,
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Microglia
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emulates peripheral macrophages, Phagocytize, scavenge CNS for plaques, damaged neurons and infectious agents
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Macroglia cells
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Astrocytes, Oligodendrocytes, Ependymal cells, Radial glia, Schwann cells, satellite cells, enteric glial cells
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Astrocytes role in brain metabolism
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Take up glucose to supply energy, regulate K+, recycle neurotransmitter (Glutamate-taken up/synthesized by astrocyte)
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Acetylcholine
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Major neurotransmitter, fast neurotransmission, activate nicotinic cholinergic receptors and muscarinic receptors
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Breakdown of Acetylcholine
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use of acetylcholinesterase and water to break down into choline and acetate and water
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Somatic
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refers to body: body wall, head, neck, trunk, and limbs (muscles).
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Homeostasis
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maintenance of constant internal environment in response to external stimuli
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Pertubation
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Sensed activation of CNS, leading to increase in autonomic (efferent) outflow
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Cathode
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Negatively charged
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Anode
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Positively charges, usually spinning
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mAs
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current, milli-amps, total number of x rays produced
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kVp
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Killi-voltage, energy
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Where are x ray beams produced
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When the cathode shoots electrons to the anode, the anode creates x ray beams and shoots it out
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Bremsstrahlung
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Electron braking, slowing it down, the SPECTRUM of x ray energies, high atomic number to create a more medically usable image
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Characteristic x rays production
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Yields x rays of specific energies for a given target atom. Produces discrete x ray energies. direct interaction
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Compton Scatter
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High energy beams = more scatter of the x ray beam, Degrades image quality (bad)
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Photoelectric Absorption
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due to Lower energy beams, Allows for detection of different tissues (good)
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Photoelectric effect
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complete absorption of the x ray without forward scatter (white spot) , effect increases with higher Z matter and low energy x ray beam
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Half Value layer
x ray attenuation, image due to thickness and what the material is made of
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No x ray interaction
film exposure (black)
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Neuron
the functional signaling unit of the nervous system
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Oligodendrocytes
Produce the myelin sheath around the axon which insulates and allows electrical signals to propagate,
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Astrocytes
Secrete gliotransmitters to minimize damage, regulate external chemical environment by signaling with calcium
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Ependymal cells
line the spinal cord and ventricular system of the brain, synthesize/secrete CSF, sensing the environment in the CSF and communicate information in a polarized way to brain tissue
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Radial Glia
Regulate synaptic plasticity (changing of ampliication of the signal), bidirectional communication with neurons, very important in development of nervous system
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Schwann cells
Myelination in PNS, phagocytic activity,allow regroath of PNS neurons
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Enteric glial cells
Found in GIT, regulate homeostasis and muscular digestion
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Satellite cells
Surround sensory, sympathetic, and parasympathetic ganglia, regulate external chemical environment (gap junction/ Ca), sensitive to inflammation
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Neoplastic Vasculature
Abnormal structure (leakage, fragility) signaling (paracrine and autocrine), continued growth of vasculature
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Tissue and Metastasis
Loosening of intracellular junctions, attachment, Degradation, Migration
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Carcinomatosis
Direct invasion or implantation
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Routes of Mastasis
Hematogenous, Lymphatic, Direct invasion or implantation
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Local Neoplastic effects
Neoplastic effusion or edema: Lymphatic infiltration/obstruction, Expansile mass in confined space, damage to adjacent tissue
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Initiator of Neoplastic disease
mutagens, DNA damage, direct reacting carcinogen, Procarcinogen (requires metabolism to activate), DNA replication (irreversible)
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Promoters of Neoplastic Disease
Positive selective pressure for initiated cells....
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DNA mutagens and tumor initiation
Physical (radiation), chemical (plant toxins), Biological (bacteria/virus) mutagens
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Projections from the spinal cord
Somatic, sympathetic and Parasympathetic
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Somatic projection
Cell bodies lie in CNS, synapse at effector organ (skeletal muscle), nicotinic synapse, muscle subtype of the nicotinic receptor
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Sympathetic Projection
Nicotinic receptor, epinephrine, Synapse in ganglia, outside spinal cord they are nicotinic, effector organs are noradrenaline, muscarinic
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Parasympathetic Projection
Nicotnic (ganglionic synapse) and Muscarinic
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Nicotinic receptor
ligand gated ion channels that mediate fast synaptic transmission of the neurotransmitter, respond to nicotine
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Muscarinic receptor
G coupled proteins which are slow metabolic response via second messenger cascades, respond to muscarine
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Nicotinic agonists
Activating: Phenyltrimethylamonium, nicotine, acetylcholine
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Muscarinic agonist
Activating: Muscarine, acetylcholine
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Nicotinic antagonist
Blocking: Complicated structures which are selective for receptors they affect, Trimethaphan
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Muscarinic antagonist
Blocking: Atropine
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Regulators of acetylcholine
Synthesis in nerve terminal (Choline + Acetyl coenzyme A), Transportation via vessicles (ATPase, ChAT, and VAChT)
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Breakdown of Acetylcholine
Acetylcholinesterase (AChE) present in insecticides
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Muscarinic G- protein coupled receptors
Inhibition Adenylyl cyclase, Activation PLC, DAG, and IP3, regulate K+ channels
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Glutamate
Derived from blood-borne glucose and AA that cross the BBB release from the nerve terminal, neurotransmitter
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Glutamate receptor subtypes
Ionotropic (NMDA, AMPA, Kainate), Metabotropic (Class I, II, III)
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Ionotropic glutamate receptor
Utilizes a pore to allow molecules to pass through, fast responses
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Metabotropic glutamate receptor
Slow reacting, utilizes G coupled proteins to generate a response or activate ionotropic receptors
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GABA receptor structure
5 subunits, GABA binding site
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GABA synthesis
GABA shunt during the TCA cycle
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Metabotropic GABA receptors
Inhibitory receptors, prevents sodium channels from opening due to hyperolarization of the neuron
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GABA receptors
GABAa (ionotropic), GABAb (metabotropic)
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Adaptive changes of cells
Atrophy, Hypertrophy, Hyperplasia, Metaplasia
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Nonadaptive changes of cells
Dysplasia, Neoplasia, Carcinoma in situ
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Benign tumor (3)
Local growth, expansion, pendunculation, encapsulated by fibrous tissue, well-differentiated, low mitotic index, solid supporting stroma, excision curative, Adenoma
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Malignant tumor (3)
Metastasis, expansion and invasion/infiltration, unencapusulated, Anaplasia (poorly differentiated), increased mitotic index, local recurrence, carcinoma
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Epithelial tumor derived from:
Any embriologic tissue, glandular, non-glandular, Ductular
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Mesenchymal tumors Derived from:
Stromal, "Connective tissue" (muscle, fibroblasts, adipose tissue, bone and cartilage), Blood and Lymph, Hematopoietic tissue, cells with a matrix
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Round cell tumors
Hematopoietic, exceptions in nomenclature, Leukemiasm mastocytoma vs mast cell tumor, lymphosarcoma vs lymphoma, individualized cells, round, infiltrate adjacent tissue in streams
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Cancer
unregulated growth of immortal cells capable of local tissue invasion and distant spread (metastasis), caused by the environement and genetics, once changes its irreversible
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Initiation of cancer
Starting down the neoplastic pathway, Genetic irreversible stage, EGF receptor is mutated
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Promotion of cancer
Selective pressure, Nongenetic reversible, secretes growth factor, preneoplastic lesion/benign tumor
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Progression of cancer
Genetic/nongenetic, irreversible (additional mutations)/reversible (increased expression in growth factor), malignant
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Preneoplastic changes
Hypertrophy, hyperplasia, metaplasia, dysplasia
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Metaplasia
Altered differentiation of cells, ex: change of epithelial cell to squamous cell
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Dysplasia
Loss of architectural arrangement, increase in cell pleomorphism
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Pleomorphism
Describes specific cells, on cells type with differences in appearance, Homogenous
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Neoplasia
Physiologic-independent new growth- may be benign or malignant, growth of cell that is not responsive to normal cues of the body
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Carcinoma in situ
non-invasive neoplasm- cellular atypia but intact basement membrane
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Anisocytosis
Variation in cell size and shape
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Anisokaryosis
Variation in nuclear size and shape
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Anaplasia
Loss of features associated with differentiation of a particular cell type- hard to identify what type of cell is present
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Homogenous
Describes entire cell population, 1 cell type throughout the population, indicative of cancer
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Heterogeneous
Describes entire cell population, comprised of several cell types, indicative of normal organ structure or physiological process
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Monomorphism
Describes specific cells, homogenous population of cells that appear to be the same
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Benign mesenchymal tumor naming
Cell of origin: _____ +oma
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Malignant Mesenchymal tumor naming
Cell of origin: _____ + sarcoma
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Epithelial tumor feature
large, polygonal cells with a defined border, Benign: Pedunculated (contains a stalk and becomes a polyp or papilloma), Malignant: scirrhous response or necrosis
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Scirrhous response (malignant epithelial tumor feature)
reactive tissue stroma, scar formation
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Necrosis (malignant epithelial tumor feature)
ulceration, umbilication
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Benign epithelial nomenclature
Adenoma, glandular
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Malignant epithelial nomenclature
Carcinoma
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Hamartoma
Overgrowth of cells
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Choriostoma
Overgrowth of cell that are not normally present
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Teratoma
Germ cell tumor (contains endo, ecto, meso- tissue)
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Angiogenesis
Vascularization occurs to allow tumors to secrete their own growth factors
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MMP
Matrix metalloproteases function to degrade tissue matrix to allow the invasion of tumor cells
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Sprouting Angiogenesis
Hypoxia of the tumor causes a release of growth factors to allow vascularization to occur
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Vasculogenesis
Line blood vessels, some tumors are able to form their own vascular channels by recruiting EPC (endothelial progenitor cell)
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Neoplastic Vasculature
Abnormal structure (leakage), abnormal signaling (paracrine and autocrine), and continued growth of vasculature
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Tumor angiogenesis
Tumor progression, continued growth/metastatic disease
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Solid tumor growth
Intra-tumoral hypoxia, necrosis of tumor tissue
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Malignant tumor growth steps
1. Loosening of intracellular junction, loosens its attachment to basement membrane and pulls itself towards the BM, degradation of collagen, Migrate through BM
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Tumor- stromal interactions
Tumor infiltrating WBC, Tumor matrix, Necrosis & Hypoxia, Tumor Vasculature, Tumor population
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Tumor Infiltrating WBCs
secrete cytokines, change tumor stroma and interact with tumor itself to destroy or propagate tumor
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Necrosis & Hypoxia
stimulates angiogenesis, increase proteins and enzymes which help with cell survival
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Tumor population
Making and secreting growth factors to activate themselves and neighbors
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TUmor Vasculature
Secrete growth factors and signaling molecules, tumor vessels they're recruiting
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Tumor Matrix
Fibroblasts proliferate and signal growth
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Acceptable Margin
400-500 um
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Routes of Metastasis
Hematogenous (blood supply), Lymphatic, Direct invasion or implantation (carcinomatosis)
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Lymphatic invasion of metastatic disease
Draining lymph nodes used to biopsy, subcabsular sinuses are affected first and then invasion of the lymph node
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Carcinomatosis
Direct spreading, cells released and wherever they touch cancer grows
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Neoplastic effects
Local/regional, effusion lymphatic infiltration, expansile massin confined space, damage to adjacent tissue
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Paraneoplastic syndromes
Systemic effects of neoplastic disease, complex pathogeneses, significant morbidity, may precede tumor identification
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Cachexia
paraneoplastic syndrome, complete reprogramming of the metabolism, increases fat store degradation, increases breakdown of muscle and inhibits new muscle formation, anaerobic glycolysis
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Initiators of neoplastic disease
mutagens, DNA damage or mutation, Procarcinogen (require metabolism to activate, Irreversible!
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DNA mutagens & Tumor Initiation
Physical, Chemical, Biological mutagens
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Physical Mutagens
UV damage, exposed skin/mucus membranes, squamous cell carcinoma, chronic inflammation or trauma (post fracture osteosarcoma)
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Chemical Mutagen
Vaccine-associate sarcomas: fibrosarcoma, osteosarcoma Mycotoxin, Braken fern
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Viral mediated Oncogenesis
DNA virus: Transform by expression of viral protein, RNA virus: Retrovirus (viral integration in genome, random) leukemia
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Papillomavirus and cancer
E6 protein: p53 degradation, E7: sequesters Rb in cytosol
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Ways to record radiographic images
Photosensitive film, computerized images (computed radiography, digital radiography, computed tomography)
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Composition of x ray film
Base (stable, inert, support for emulsion), Emulsion (AgBr crystals in emulsion)
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Film
used for high resolution, due to the size of the crystal
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Intensification screens
x-rays photons emit light photons to expose film, made of rare earth screens which require special films and lights, cassette
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kVp in film
Kilovoltage, controls energy behind the x ray beam, high contrast=low kVp, imaging characteristic, affects overall exposure and how the beam interacts with tissue, controls exposure and CONTRAST
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mAs in film
Milliamperage times seconds, total number of x rays produced during exposure, double mAs=double the radiation exposure, controls exposure
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Contrast in film
High contrast is very black and white, Good for looking at bones (Low kVp, high mAs)
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Latitude in film
Lots of shades of grey, Good for soft tissue in the thorax (High kVp, low mAs)
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Four contributors to subject contrast
tissue thickness, Photoelectric effect (PE), Compton's scatter, Beam energy- low kVp favors increased PE and contrast
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Motion in exposure time
short exposure, high kVp, keeping mAs small so the image is taken quickly
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Thorax radiology technique
Inspiration, short exposure time low mAs, high kVp
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Abdomen radiology technique
Exposure between expiration and inspiration, Longer exposure times (higher mAs), kVp should be kept as low as possible
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kVp and mAs relation in film
15% change in kVp will result in same change in film as halving or doubling mAs
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Scatter radiation
Originates within patient due to compton interactions, related to volume and density of the object, 50-70% of x rays reaching the cassette are scatter
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Film proocessing
Development, Fixation, Washing
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Recording with x ray film pos/neg
Pos: inexpensive, permanent, high resolution, Neg: complex development and storage, susceptible artifacts, low tolerance for error
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Cassette Based radiology
Stores x ray information, laser passes over Storage phosphor, electrons fall form excited state to give off light, light detectors digitize and record the light emitted
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Digital radiology
light emitting crystal converts x rays to light, 1 crystal per pixel, light from each pixel is represented as a shade of gray within seconds, high room for error!
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Veterinary genetics
The study of inherited disease that occur in animals
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Ultrasound
Diagnostic modality which allows you to see sound, for soft tissue, cross-section imaging
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Ultrasound steps
Sound is sent out, hits an object, reflected back.
| Loud reflections are white, no reflections are black
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ECHOgenic
having or producing echos, white
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ECHOrich
Full of echos
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isoECHOic
same echos as another organ
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AnECHOic
Free of echos, Urine and bile, black
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How does ultrasound work?
Signal production via Piezoelectric crystal pulsed which creates a pulsed electric energy, the machine listens for the vibrations and mapping it
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Footprint of ultrasound machine
The window where signal is sent and received
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Frequency of Ultrasound
Cycles per second, MHz, penetration
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Wavelength of ultrasound
Distance traveled per cycle mm, resolution
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Velocity in ultrasound
1540 m/s soft tissue constant, V=Frequency x Wavelength (inversely related)
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High Frequency Transducers
Better Resolution, Poor Penetration
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Low Frequency Transducers
Better depth Penetration, Resolution is decreased
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Axial Spatial Resolution
Along the axis of the beam, improves with higher frequency and shorter wavelengths
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Determinants of Image Quality
Frequency of the transducer, #of crystals in transducer, machine quality, and patient (size, shape, examination)
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Ultrasound image
Image based on fate of signal as it enters the patient and returns to probe, Attenuation (striping or weakening of ultrasound beam): Absorption, scattering, reflection
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Acoustic impedance
unique tissue characteristic, aids in distinguishing organs, high AI are reflective
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Reflection
Larger differences in acoustic impedance mean more reflection, less penetration
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Orders echogenicity hypoechoic to hyperechoic
Urine, Renal Medulla, Renal Cortex, Liver, Spleen,Prostate, Renal Sinus, bone/Gas (my cat likes sunny places)
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Hyperechoic
Mineral, gas, Fat, fibrous tissue, bright and highly reflective
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Hypoechoic
water, fluid, edema, lymphoma, cell populations, black not reflective, ascities urine, Bile and blood
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Liver Ultrasound
Slightly course echotexture, Hypoechoic compared to spleen
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Spleen Ultrasound
Fine repeatable echotexture, hyperechoic compared to liver
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Artifacts
Reverberation, Shadowing, Enhancement, Edge Shadowing, Mirror Image
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Reverberation
Sound bouncing back and forth between two strong reflectors, GAS and skin surface
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Dirty acoustic shadowing
Billions of reverberation artifact between probe and soft tissue, Gas, Black
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Clean (sharp) shadowing
Mineral, calculus, urinary bone, bright white with black distal triangular region
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Acoustic enhancement
Through transmission artifact, increased echogenicty distal to an anechoic structure (black with increased bright), Fluid filled structures
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Edge shadowing
Ultrasound beam strikes a curved surface which refracts (inward/outward) convergent or divergent, results in decreased in beam energy/intensity
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Mirror Image
Results in mirror image across a strong reflector usually gas/soft tissue interface (Liver diaphragm/Lung interface) due to improper depth setting
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CT general charecteristics
High detail cross-sectional images, Minimal anatomic superimposition, Ability to reformat to view anatomy in any plane or in 3 D
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CT image formation
Relies on differences in tissue densities, dense/bone= bright, low density= dark, Density measured in Hounsfield units
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Function of Nervous system
Communication and control network, reaction of organism to the environment (internal/external)
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Neural circuits
Sensory detection (changes in environment), Information processing, change in function/behavior
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2 parts of the Nervous system
Central nervous system, Peripheral nervous system
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Central nervous system
Brain and spinal cord, cell neuronal body resides here
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Peripheral nervous system
Nerves and nerve fibers taking information to and from the brain to peripheral tissues, Cranial nerves (connects head and body), Spinal nerves (spinal cord, neck, trunk, tail, limbs) ~interaction of CNS to PNS
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Autonomic Nervous system
Involved in special senses (hearing, vision, smell), motor system that controls smooth and cardiac muscle, glands and other visceral organs, "fight or flight"
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Sensory (afferent) axon
Peripheral nerves contain axons that conduct impulses to the CNS
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Motor (Efferent) axon
Peripheral nerves contain axons that conduct impulses from the CNS to muscle and glands of the body
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Neuron pathways of ANS
Two neuron pathway: Preganglionic and Postganglionic
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Preganglionic
Cell body in CNS, myelinated nerve fiber, can affect many postganglionic fibers
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Postganglionic
Cell body outside CNS found in a ganglion in PNS, nonmyelinated nerve fiber
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Subdivisons of ANS
Sympathetic and Parasympathetic
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Sympathetic
Preganglionic neurons (cell body) located in thoracic and lumbar spinal cord (Thoracolumbar)
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Parasympathetic
Preganglionic neurons (cell body) in brainstem and sacral spinal cord (craniosacral)
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Sympathetic and Parasympathetic
Effects are coordinated, reciprocal or synergistic, tonically (always) active, differ
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Post ganglionic neurons cell body locations
Paravertebral ganglia, Prevertebral ganglia, Terminal ganglia
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Paravertebral ganglia
two sets of ganglia one lateral to each side of the spinal cord set of ganglia is linked longitudinally running axons to form sympathetic trunk (chain ganglia), sympathetic only
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Prevertebral ganglia
located in the abdomen, mostly sympathetic
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Terminal ganglia
in or around viscera, parasympathetic, synapse in target tissue
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Parasympathetic preganglionic and postganglionic fibers
```
Preganglionic= long
Postganglionic = short
```
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Sympathetic preganglionic and postganglionic fibers
```
Preganglionic= short
Postganglionic = long
```
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Sympathetic - Physiological
Catabolic, prepares for action, May be activated globally including release of epinepherine from adrenal gland, Fight or flight
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Parasympathetic - Phsyiological
Anabolic, promotes vegetative functions, lacks massive activation potential of sympathetic system, rest and digest
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Two major neurotransmitters in ANS
Acetylcholine (ACH) cholinergic receptors, norepinepherine acts on adrenergic receptors
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Sympathetic Pharmacology
Preganglionic neurons: release acetylchoine onto nicotinic receptors
Postganglionicneaurons release norepinephrine onto alpha or beta receptors on target
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Parasympathetic Pharmacology
Preganglionic neurons release acetylcholine onto nicotinic receptors,
Postganglionic neurons release acetylcholine onto muscarinic receptors or target
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Peripheral nerves of ANS
contain sensory (afferent) neurons, involved in generating reflexes but also in mediating sensory modalities such as thirst, nausea, hunger, and pain
