Exam 1 Review: Neuroanatomy, Neurophysiology, and Neuropharmacology

Flashcards covering key concepts from lectures on Neuroanatomy, Neurophysiology, and Neuropharmacology for Exam 1 Review.

What is Phrenology?

A 19th-century concept assigning separate functions to cortical areas, matched to behaviors, skills, or personality, based on bumps on the skull thought to overlie enlarged brain regions.

Which two scientists were instrumental in developing the Neuron Doctrine, and what does it state?

Camillo Golgi developed the staining method, and Santiago Ramón y Cajal used it to propose the Neuron Doctrine, which states that the brain is composed of independent cells and signals are transmitted from cell to cell across gaps (synapses).

Describe the main characteristics and locations of unipolar, bipolar, and multipolar neurons.

Unipolar neurons have a single extension branching in two directions, forming receptive and output zones, and are the fastest. Bipolar neurons have one axon and one dendrite, usually sensory, found most often in the retina. Multipolar neurons have one axon and many dendrites, and are the most common type.

What are the four functional zones of a neuron and their primary roles?

Input zone collects and integrates information; Integration zone makes the decision to produce a neural signal; Conduction zone transmits information over distances; Output zone transfers information to other cells.

Differentiate between sensory (afferent), interneurons, and motor (efferent) neurons.

Sensory (afferent) neurons respond to the environment (e.g., light, odor, touch) and send input towards the brain. Interneurons integrate information within the CNS, receiving from sensory and sending to motor neurons. Motor (efferent) neurons send input away from the brain to muscles or glands.

What are the key functions of Astrocytes, the most numerous glial cells in the brain?

Astrocytes fill spaces between neurons, provide structural support, contribute to the blood-brain barrier, and regulate the composition of the extracellular space.

Explain the role of Oligodendrocytes and what occurs in Multiple Sclerosis (MS).

Oligodendrocytes create the myelin sheath, which speeds up signal transmission. In MS, oligodendrocyte injury from an autoimmune attack damages the myelin sheath, causing signals to travel slowly throughout the body.

What are Microglia and Ependymal Cells responsible for?

Microglia clean up debris from dying neurons and glia. Ependymal cells line the ventricles and make and absorb CSF.

What are dendritic spines and what is unique about them?

Dendritic spines are tiny growths off the dendrite that are major sites of synaptic transmission. They increase surface area and exhibit neural plasticity, meaning their number and structure are rapidly altered by experience.

What are the structural and functional divisions of the nervous system?

Structurally, it divides into the Central Nervous System (CNS - brain and spinal cord) and Peripheral Nervous System (PNS - everything else). Functionally, it divides into the Autonomic Nervous System (Sympathetic for 'fight or flight' and Parasympathetic for 'rests and digests') and Somatic Nervous System (voluntary movement).

Define the directional terms: Anterior, Posterior, Dorsal, Ventral, Medial, Lateral, Ipsilateral, Contralateral, Proximal, Distal.

Anterior: head end; Posterior: tail end; Dorsal: toward the back; Ventral: toward the belly; Medial: toward the middle; Lateral: toward the side; Ipsilateral: same side; Contralateral: opposite side; Proximal: near center; Distal: toward periphery.

What is the difference between white matter and gray matter in the brain?

White matter consists of axon bundles, appearing white due to myelin sheaths. Gray matter consists of neuron cell bodies.

What are the primary functions of the Basal Ganglia, Limbic System, and Cerebellum?

The Basal Ganglia control movement. The Limbic System is involved in emotional memory and regulation. The Cerebellum is crucial for motor coordination and learning.

What are meninges and what are the three main layers?

Meninges are the 'brain wrappings'. The three main layers are the Dura mater (outermost), Arachnoid membrane (middle), and Pia mater (innermost).

What is hydrocephalus and how is it caused?

Hydrocephalus is the buildup of CSF in the ventricles due to a blockage in CSF flow. It is treated with a VP shunt to drain fluid into the abdominal cavity.

How do CT scans and MRIs differ in their imaging technique and what they show?

CT (computerized axial tomography) scans use X-ray absorption to show tissue density, with denser tissue appearing whiter. MRI (magnetic resonance imaging) uses proton emissions to create high-resolution images, also showing tissue density.

Name three methods for imaging brain activity and briefly describe what they record.

PET (positron emission tomography) scans measure emissions from injected radioactive chemicals to identify active brain regions. fMRI (functional MRI) detects changes in brain metabolism in active areas. DTI (diffusion tensor imaging) images axons to show brain connections.

What are microtubules and what is their function in a neuron?

Microtubules are composed of tubulin and act as 'rail tracks' for transporting molecules along neurons via motor proteins.

Differentiate between anterograde and retrograde axoplasmic transport, and name the motor proteins involved.

Anterograde transport moves molecules from the soma to the axon terminals, facilitated by Kinesin. Retrograde transport moves molecules from the terminals to the soma, facilitated by Dynein.

In the case of Rolf, what condition did he have, and which glial cells were affected?

Rolf had Alexander disease, where astrocytes fill with GFAP protein and fail in their function.

What two forces govern ion flow across a semipermeable membrane?

Diffusion, where ions flow from high to low concentration, and Electrostatic pressure, where ions flow towards oppositely charged areas.

What is the typical resting membrane potential of a neuron, and what causes its negative charge?

The typical resting membrane potential is -60 mV, and its negative charge is primarily due to intracellular proteins.

At rest, where are Sodium (Na+) and Potassium (K+) ions primarily concentrated, and in which direction do they flow when their channels open?

At rest, Na+ is high outside the cell and low inside; it moves into the cell when channels open. K+ is low outside and high inside; it moves out of the cell when channels open.

How does the Sodium-Potassium pump help maintain the resting potential?

The Sodium-Potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, using 1 ATP molecule, thus going against concentration gradients to reset the cell back to resting potential.

What key difference distinguishes graded potentials from action potentials?

Graded potentials occur in dendrites, vary in amplitude based on stimulus intensity, and can be EPSPs or IPSPs. Action potentials occur in the axon, are 'all-or-nothing' (non-graded), and have a uniform amplitude and pattern, with signal intensity encoded by frequency of firing.

Why do myelinated axons transmit signals faster than unmyelinated axons?

Myelinated axons transmit signals faster due to saltatory conduction, where the action potential 'jumps' between Nodes of Ranvier, skipping myelinated segments.

What are EPSPs and IPSPs, and how do they affect the chance of an action potential firing?

EPSP (Excitatory Postsynaptic Potential) is caused by Na+ influx, makes the cell more positive, and increases the chance of an action potential. IPSP (Inhibitory Postsynaptic Potential) is caused by Cl- influx, makes the cell more negative, and reduces the chance of an action potential.

What is an electrical synapse and what are its advantages?

An electrical synapse involves direct ion flow through gap junctions into adjacent neurons, offering no time delay and enabling synchronization of neurons.

Differentiate between endogenous and exogenous ligands, providing an example for each.

Endogenous ligands are molecules from inside the body that bind to receptors (e.g., neurotransmitters, hormones). Exogenous ligands are drugs and toxins from outside the body (e.g., nicotine, tetrodotoxin).

Explain what up-regulation and down-regulation of receptors are, and relate them to sensitization and tolerance.

Up-regulation is an increased number of receptors, leading to sensitization (heightened response to a drug dose). Down-regulation is a decreased number of receptors, leading to tolerance (diminished response to a drug dose).

Compare and contrast ionotropic and metabotropic receptors.

Ionotropic receptors are fast-acting, where a ligand directly causes a channel to open, resulting in a conformational change. Metabotropic receptors are slow-acting and indirect, where a ligand causes a G-protein to be released, opening a channel elsewhere and allowing for signal amplification through a cascade.

How do competitive and noncompetitive antagonists differ?

Competitive antagonists bind to the same binding site as the ligand, completely inhibiting the signal. Noncompetitive antagonists bind to a secondary site, changing the channel configuration and resulting in a partial signal.

What is the most common excitatory neurotransmitter (NT) in the CNS and what is its primary effect?

Glutamate is the most common excitatory NT in the CNS, permeable to Na+ ions, and responsible for EPSPs.

What is the most common inhibitory neurotransmitter (NT) in the CNS and what is its primary effect?

GABA is the most common inhibitory NT in the CNS, permeable to Cl- ions, and responsible for IPSPs.

Which amino acid NT is common in the spinal cord and is inhibited by tetanospasmin (from tetanus)?

Glycine is an inhibitory (Cl- permeable) NT common in the spinal cord, and its inhibition by tetanospasmin causes muscle stiffness and contractions.

What are the three main catecholamine neurotransmitters and what is their common precursor and rate-limiting enzyme?

The three main catecholamines are Dopamine, Norepinephrine, and Epinephrine. Their precursor is Tyrosine, and the rate-limiting enzyme in their synthesis is Tyrosine hydroxylase.

What are the two major dopamine pathways and their associated functions?

The Mesolimbocortical pathway (VTA to nucleus accumbens, cortex, hippocampus) is involved in addiction, learning, and schizophrenia. The Mesostriatal pathway (substantia nigra to striatum) is involved in motor control.

What are endogenous opiates and what effects do they produce?

Endogenous opiates like enkephalins, endorphins, and dynorphins bind to opioid receptors, relieving pain (analgesia) and creating a feeling of well-being. They can also be addictive.

How do SSRIs like Prozac and Zoloft work as antidepressants?

SSRIs (Selective Serotonin Reuptake Inhibitors) block the reuptake of serotonin, leading to an accumulation of serotonin in the synapse, with fewer side effects than older antidepressants.

What drug class do benzodiazepines belong to, and what is their mechanism of action?

Benzodiazepines are anxiolytics (tranquilizers) and function as GABA agonists, reducing nervous system activity by increasing the inhibitory effects of GABA.

Describe the biphasic effects of alcohol.

At low doses, alcohol acts as a stimulant by turning off cortical inhibition, reducing social constraints and anxiety. At high doses, it acts as a sedative.

What is the active agent in marijuana and how does it interact with brain receptors?

The active agent in marijuana is THC (tetrahydrocannabinoid). It binds to cannabinoid receptors in the brain that normally bind endocannabinoids like anandamide and 2-AG, which are retrograde signaling molecules.

How does cocaine produce its effects in the brain?

Cocaine blocks monoamine transporters, especially dopamine transporters, which increases the time that dopamine stays in the synapse, leading to enhanced feelings of pleasure and well-being.

What is the primary mechanism of action for amphetamines and methamphetamines?

Amphetamines and methamphetamines are synthetic stimulants that block the reuptake and increase the release of catecholamines, similar to cocaine's effects.

How do stimulant medications like Adderall and Ritalin help treat ADHD?

These stimulants inhibit impulsive behavior by stimulating inhibitory pathways, specifically cortico-thalamic networks, in the brain.

What is the basis for addiction in the brain, and which brain system is primarily involved?

The basis for addiction is reward, the positive effect an agent has on the user. The mesolimbocortical dopamine system (VTA) is the major reward system involved.

Why is recovering from addiction often difficult, even years after quitting?

Recovery is difficult because drugs remodel the brain, specifically through the buildup of delta FosB in neurons, which remains activated for years and remodels the nucleus accumbens, perpetuating craving.

What type of pharmacological treatment for addiction involves mimicking the drug's effects but in a milder way?

Agonistic treatments mimic the drug's effects but are milder, such as methadone for opiate addiction or Chantix for nicotine dependence (as a partial agonist).

In the case of OJ who had a seizure during alcohol withdrawal, what compensatory change contributed to his seizure?

His seizure was caused by a compensatory increase in glutamate receptors that occurred over time due to chronic alcohol use, as alcohol inhibits glutamate at low doses.

What is Rett Syndrome and who does it primarily affect?

Rett Syndrome is an X-linked progressive ASD with intellectual disability that primarily affects girls in early childhood, after seemingly normal development for the first year, leading to loss of purposeful hand use, spoken language, gait abnormalities, and hand stereotypes. Males with the syndrome often die in miscarriage.

What are the three germ layers of the neural plate and what does the neural plate become?

The three germ layers are the Endoderm, Mesoderm, and Ectoderm. The neural plate eventually rolls up to become the CNS (central nervous system).

List the six stages of nervous system development.

The six stages are: Neurogenesis, Cell migration, Differentiation, Synaptogenesis, Neuronal cell death, and Synapse refinement.

What is microcephaly and what virus can cause it during pregnancy?

Microcephaly is a condition characterized by a small head, often caused by a failure of neurogenesis. The Zika virus, if contracted by the mother during pregnancy, can lead to microcephaly in the baby.

How do chemoattractants and chemorepellants guide axons during development?

Chemoattractants are chemicals that attract certain growth cones, while chemorepellants repel them, acting at close or long range to guide axons to their target locations based on 'chemoaffinity'.

What process is Medulloblastoma associated with a failure to complete during development?

Medulloblastoma is a cancer caused by a differentiation failure, where cells keep dividing but never differentiate into their specialized types.

In the context of synaptic development, what observation is made about autistic children's brains?

Autistic children often make too many synapses, leading to excessive brain connectivity.

Describe the process of neuronal cell death (apoptosis) and the role of caspases.

Neuronal cell death is programmed cell death (apoptosis) triggered by Ca+ influx. This causes mitochondria to release Diablo, which binds to IAPs (inhibitors of apoptosis proteins), preventing them from inhibiting caspases. Without IAP inhibition, caspases become active and dismantle cellular proteins and DNA, leading to cell death.

What disorder is characterized by impaired cell death due to the absence of the FMRP gene?

Fragile X syndrome is an X-linked genetic disorder where the absence of the FMRP gene impairs neuronal cell death.

What are neurotrophic factors and what is their purpose?

Neurotrophic factors are chemicals made by target cells that neurons compete for. Their purpose is to choose which synapses to save and to ensure the survival of neurons that successfully make these connections (e.g., NGF, BDNF).

Why does Amblyopia cause blindness in a single eye, and how does it relate to synapse refinement?

Amblyopia, caused by early vision impairment and eye misalignment, leads to blindness because the brain decides not to strengthen synapses in the weaker, misaligned eye during synapse refinement, effectively neglecting its input.

What are some common clinical features of Autism related to communication and social interaction?

Common features include impaired communication/language (ranging from nonverbal to complex skills, sometimes with echolalia), lack of social interaction (impaired nonverbal behavior, failure to share enjoyment, poor eye contact), and a strong preference for predictability and routine.