Neurotoxicity I

Pharmacology 450 with Lookingland at Michigan State University

About this deck

By: Anna Stala
Textbook: Casarett & Doull's Essentials of Toxicology Second Edition (Casarett and Doull's Essentials of Toxicology)
Created: 2011-04-11
Size: 32 flashcards
Views: 6

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Afferent/Sensory Neurons

communicate sensory information from sensory receptors to CNS

Somatic Nervous System

transmits electrical signals from CNS to skeletal muscles. Voluntary controlled movements

Autonomic Nervous System

transmits electrical signals from CNS to smooth muscle in viscera, cardiac muscle and glands. Involuntary control.

Sympathetic Nervous System

"fight or flight" dilates pupils, inhibits flow of saliva, dilates bronchi, accelerates heartbeat etc.

Parasympathetic Nervous System

"rest and digest" stimulates flow of saliva, slows heartbeat stimulates peristalsis and digestion

Neurons

conduct action potentials. for highly complex connections with other neurons.

Glial Cells

Support cells for neurons. 1:10 neuron to glial cell ratio

Cell Body

defined by the presence of the nucleus-contains DNA. Round, centrally located. Direct Cell's metabolism. Controls protein synthesis. Where general integration occurs

Dendrites

Input zone. Receives information from other neurons. Connections with many neurons. If enough inputs, the cell's Axon will generate an action potential.

Axon

Transmits neural signal away from cell body. One axon per cell. Two distinct parts: Axon- conducting zone and the Axon Terminal- output zone. Axon can branch out to reach out to many different places.

Astrocyte

star shaped cell. regulate extracellular composition of brain fluid. sucker-like extensions attached to blood vessels.

Microglia cells

specialized cells. Act as mobile macrophages. They remove debris from injured or dead cells and create a healthy environment

Oligodendrocytes

form extensions that wrap around portions of several axons, located in the CNS Schwann Cells, like oligo's in PNS, but can only wrap around a portion of one axon.

Myelin Sheath

White fatty casing around axons. Acts as electrical insulator, increasing the speed of the neural signal. It is not present on all cells.

Action Potential

Depends on the movement of ions across the plasma membrane. Ions involved: Sodium, Potassium, Chloride, Organic Anions. Neurons have a resting membrane potential; different ions are concentrated on different sides of the membrane.

Movement of the action potential

Na+ influx depolarizes adjacent segments of the axon, opening new voltage-gated Na+ channels. The refractory period ensures the AP moves in one direction, down the axon towards the terminal region.

Passive conduction

ensure the adjacent membrane will polarize and the action potential continues to move down the membrane. More efficient form of conduction is saltatory conduction

Saltatory Conduction

Myelination provides insulation that resists the flow of ionic current. Action potential occur at breaks in the myelination called Nodes of Ranvier.

Chemical Synapse

Specialized junctions allowing communication between neuron and target cells. Chemical synapses use chemical signals called neurotransmitters for this communication

Neurotransmitters

released by the presynaptic neuron, then diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane.

Post Synaptic Effects of Neurotransmitters

Neurotransmitters bind to receptors gates ion channels in two ways: Ionotropic Receptors and Metabotropic Receptors

Ionotropic Receptors

Directly controls an ion channel. Fast, short-lived neurotransmission.

Metabotropic Receptors

Activate G proteins that initiate intracellular signaling pathways. Slow sustained response to neurotransmitters.

Factors in Neurotoxicity

High metabolic rate of neurons. Blood Brain Barrier

Blood Brain Barrier

Tight endothelial capillary/ astrocyte junction increase resistance to passage of molecules. Only lipophilic molecules can pass rapidly into the brain without a transporter. Protective mechanism. Circumventricular organs are "leaky" regions

Circumventricular Organs

The blood Brain Brier is incomplete in these areas, hence "leaky". These organs monitor the composition of the blood and secrete various hormones and neurotransmitters.

Examples of Circumventricular Organs

Area Postrema: vomit center. Pineal Gland: regulates releases of melatonin; cardiac rhythms. Median Eminence: release of hormones to regulate the anterior pituitary gland.

Weakening the Blood Brain Barrier

Hypertension; Development; Microwaves: Radiation; Infection; Trauma, Ischemia, Inflammation; Pressure

Neuropathy

loss of the entire neuron. irreversible

axonopathy

loss of the axon and its associated myelin, cell body remain in tact. reversible

myelinopathy

direct loss of the myelin; loss of the oligoodendrocytes/ Schwann cells; separation of myelin from axon; sometimes can be reversible

Synaptic Function

activating or inhibiting receptors. Altering amount of neurotransmitter left to activate receptors.

About this deck

By: Anna Stala
Textbook: Casarett & Doull's Essentials of Toxicology Second Edition (Casarett and Doull's Essentials of Toxicology)
Created: 2011-04-11
Size: 32 flashcards
Views: 6

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis