BMS1052 Human Neurobiology: ANS, Neurodevelopment, Pharmacology, and Memory

Comprehensive vocabulary flashcards covering the Autonomic Nervous System, Hypothalamus, Autonomic Pharmacology, Central and Peripheral Neurodevelopment, and Learning and Memory.

Autonomic Nervous System (ANS)

The involuntary motor division of the peripheral nervous system originating from the hypothalamus that regulates smooth muscle, cardiac muscle, and glands via a two-neuron pathway.

Somatic Nervous System

The voluntary motor division of the peripheral nervous system originating from the primary motor cortex that utilizes an upper motor neuron and a single lower motor neuron to innervate skeletal muscle without peripheral ganglia.

Sympathetic Division

The thoracolumbar division of the ANS mediating 'fight, flight, freeze, or fawn' responses; features short preganglionic neurons from the thoracic and lumbar spinal cord synapsing in sympathetic trunk ganglia near the vertebral column, and long postganglionic fibers that primarily release noradrenaline.

Parasympathetic Division

The craniosacral division of the ANS responsible for 'rest and digest' states; features long preganglionic fibers arising from cranial nerves and sacral spinal cord that synapse in terminal or intramural ganglia close to or within the target organs.

Intramural Ganglia

Terminal parasympathetic ganglia situated directly within the walls of their target effector organs.

Nicotinic Acetylcholine Receptor (nAChR)

An ionotropic cholinergic receptor located on all autonomic postganglionic neurons, adrenal medullary cells, and skeletal muscle motor endplates whose activation by acetylcholine invariably produces an excitatory post-synaptic potential (EPSP).

Muscarinic Acetylcholine Receptor (mAChR)

A G-protein coupled cholinergic receptor found at neuroeffector junctions of all parasympathetic target organs and sweat glands that produces either excitation (EPSP) or inhibition (IPSP).

DUMBBELLS

A mnemonic summarizing the physiological signs of excessive muscarinic receptor activation: Diarrhoea, Urination, Miosis, Bradycardia, Bronchoconstriction, Emesis, Lacrimation, Lethargy, and Salivation.

$$\beta_1\text{-Adrenoreceptor}$$

An adrenergic receptor subtype primarily located in the heart whose activation by noradrenaline or adrenaline induces an excitatory post-synaptic potential (EPSP), increasing heart rate and contractile force.

$$\beta_2\text{-Adrenoreceptor}$$

An adrenergic receptor subtype located in smooth muscles of the airways, digestive tract, urinary organs, and specific blood vessels (supplying the heart, liver, and skeletal muscles) whose activation induces inhibition (IPSP), causing dilation and increased blood flow.

$$\alpha_1\text{-Adrenoreceptor}$$

An adrenergic receptor subtype located on all sympathetic targets and peripheral blood vessels (excluding the heart, liver, and skeletal muscles) whose activation produces an excitatory response, causing vasoconstriction.

Baroreceptor Reflex

An involuntary homeostatic autonomic reflex initiated by stretch-sensitive mechanoreceptors in the aorta and carotid artery that transmit blood pressure alterations via visceral afferents to the medulla, adjusting sympathetic and parasympathetic outflow.

Hypothalamus

A small mid-sagittal diencephalic structure situated ventral to the thalamus that integrates internal and external stimuli to maintain homeostasis and direct endocrine and autonomic functions.

Periventricular Zone of the Hypothalamus

The innermost hypothalamic zone lining the third ventricle that contains specialized neurosecretory cells for endocrine regulation and neurons coordinating the autonomic nervous system.

Magnocellular Neurosecretory Cells

Large hypothalamic neurons whose axons project down the infundibulum via the hypothalamic-hypophyseal tract to secrete oxytocin and vasopressin directly into the capillary beds of the posterior pituitary.

Parvocellular Neurosecretory Cells

Hypothalamic neurosecretory neurons that produce hypophysiotropic hormones and release them into the capillary plexus of the hypophyseal portal system to stimulate or inhibit the secretion of hormones from the anterior pituitary gland.

Vasopressin (Anti-Diuretic Hormone / ADH)

A peptide hormone synthesized by hypothalamic magnocellular neurons and stored in the posterior pituitary that promotes renal water reabsorption, reducing urine volume and increasing blood volume and blood pressure.

Oxytocin

A hypothalamic neurohormone released from the posterior pituitary that stimulates uterine contractions during parturition and milk ejection from mammary smooth muscle during lactation.

Arcuate Nucleus (ARC)

A hypothalamic nucleus that integrates peripheral metabolic signals, featuring hunger-stimulating NPY/AgRP neurons and satiety-inducing $\alpha\text{-MSH}$/CART neurons.

Ghrelin

A peptide hormone released from the stomach during fasting that activates NPY/AgRP neurons in the arcuate nucleus to promote feeding via stimulation of the lateral hypothalamic area.

Leptin

An adipocyte-derived hormone signaling long-term energy reserves that suppresses hunger by activating $\alpha\text{-MSH}$/CART neurons in the arcuate nucleus, stimulating the paraventricular nucleus, and inhibiting the lateral hypothalamic area.

Lateral Hypothalamic Area (LHA)

A hypothalamic region that promotes hunger and feeding behavior; bilateral lesions here lead to lateral hypothalamic syndrome, characterized by severe aphagia and emaciation.

Paraventricular Nucleus (PVN)

A hypothalamic nucleus involved in satiety signaling and metabolic output that receives stimulatory projections from $\alpha\text{-MSH}$/CART neurons to suppress feeding.

Lipostatic Theory

The hypothesis proposing that the brain monitors circulating adiposity signals (such as leptin) to adjust food intake and energy expenditure, thereby defending a constant body fat mass.

Choline Acetyltransferase (ChAT)

The cytosolic enzyme localized in cholinergic presynaptic nerve terminals that catalyzes the synthesis of acetylcholine from acetyl-CoA and choline.

Acetylcholinesterase (AChE)

The synaptic enzyme that terminates cholinergic neurotransmission by rapidly hydrolyzing acetylcholine into acetate and choline within the synaptic cleft.

Uptake-1

A high-affinity presynaptic transport pump responsible for terminating sympathetic neurotransmission by clearing noradrenaline from the neuroeffector cleft back into the axonal terminal for recycling.

Atropine

A competitive muscarinic receptor antagonist that blocks parasympathetic activity, inducing pupil dilation (mydriasis) and suppressing glandular and bronchial secretions.

Botulinum Toxin

A bacterial toxin that blocks exocytotic release of acetylcholine from presynaptic terminals, producing anti-DUMBBELLS autonomic effects alongside skeletal muscle weakness and paralysis.

Pseudoephedrine

An indirectly acting sympathomimetic agent that stimulates noradrenaline release to activate $\alpha_1\text{-adrenoceptors}$, causing vasoconstriction of small mucosal vessels to relieve nasal congestion.

Myasthenia Gravis

An autoimmune disorder characterized by muscle weakness due to antibody-mediated destruction of nicotinic receptors at the skeletal neuromuscular junction; treated clinically using acetylcholinesterase inhibitors.

Neural Induction

The early embryonic process in which signaling molecules from the node instruct overlying unspecialized ectodermal cells to commit to a neural fate, forming the neural plate.

Neurulation

The embryonic process whereby the flat neural plate elevates its lateral edges into neural folds that fuse along the midline to create the hollow neural tube.

Primary Brain Vesicles

The initial three cranial swellings formed from the rostral neural tube: the forebrain , midbrain , and hindbrain .

Radial Migration

The developmental transport of newly generated neuroblasts along the elongated basal processes of apical progenitor cells from the ventricular surface toward the pial surface.

Inside-Out Cortical Layering

The spatial organizational rule of cerebral cortex assembly wherein early-born neurons settle into the deepest cortical layers while later-born neurons migrate past them to establish the outer layers.

Neuritogenesis

The initial stage of neuronal morphogenesis where a newly differentiated neuron extends actin-rich cytoplasmic protrusions (neurites) that subsequently differentiate into an axon and dendrites.

Growth Cone

The motile, actin- and microtubule-driven sensory structure at the tip of an extending axon that interprets extracellular guidance cues to direct navigation toward its synaptic target.

Synaptogenesis

The multi-step process comprising target contact, cell-cell contact stabilization, and recruitment of presynaptic vesicles and postsynaptic receptor machinery to construct functional synapses.

Gliogenesis

The generation of astrocytes and oligodendrocytes from neural progenitor cells, which begins in the central nervous system only after neurogenesis is complete.

Microglia

The resident immune and phagocytic cells of the central nervous system that derive from the primitive immune system and enter the brain via blood vessels, rather than originating from the neural plate.

Cerebral Organoids

Three-dimensional in vitro cell cultures derived from human induced pluripotent stem cells (iPSCs) that self-organize into structures modeling early human fetal brain development and architecture.

Neural Crest

A transient, multipotent migratory cell population originating from the border of the neural plate and non-neural ectoderm that gives rise to the peripheral nervous system, pigment cells, and adrenal chromaffin cells.

Epithelial-Mesenchymal Transition (EMT)

A morphological and behavioral transformation wherein premigratory neural crest cells decrease cell-cell adhesion, alter polarity, and modify matrix interactions to delaminate from the neural tube and migrate.

Sympathetic Chain Ganglia Assembly

The developmental sequence whereby trunk neural crest cells migrate ventrally between somites to the dorsal aorta, disperse longitudinally, and re-aggregate into discrete ganglia via upregulation of adhesion molecules such as N-cadherin.

Neuropilin-1 (Nrp1)

An axonal surface receptor on peripheral growth cones that mediates repulsive guidance when bound by Semaphorin-3A (Sema3A) and attractive guidance when bound by VEGF.

BDNF / TrkB Signaling in Sympathetic Development

A chemoattractive mechanism where brain-derived neurotrophic factor (BDNF) released by preganglionic nerves binds TrkB receptors on primary sympathetic ganglia, driving their dorsal migration to form secondary sympathetic ganglia.

Schwann Cells

Peripheral glial cells derived from the neural crest that myelinate and support motor, sensory, and autonomic axonal fibers in the peripheral nervous system.

Satellite Cells

Neural crest-derived peripheral glia that envelope neuronal cell bodies within sensory and autonomic ganglia to regulate their microenvironment, functioning analogously to astrocytes.

Neuroblastoma

The most common extracranial pediatric solid tumor, originating from undifferentiated neural crest neuroblasts primarily within the adrenal medulla or sympathetic ganglia.

Neurotransmitter Plasticity

The developmental phenomenon where mature autonomic neurons alter their neurotransmitter phenotype (such as sympathetic neurons innervating sweat glands converting from adrenergic to cholinergic).

Declarative Memory

An explicit memory classification requiring conscious recall, sub-divided into episodic memory (personal experiences with temporal/spatial context) and semantic memory (factual knowledge); dependent on medial temporal lobe structures.

Nondeclarative Memory

An implicit memory classification operating outside conscious awareness, encompassing procedural memory for skills and habits, classical conditioning, and non-associative learning.

Patient H.M. (Henry Molaison)

A famous surgical patient who underwent bilateral medial temporal lobectomy, causing severe anterograde amnesia and temporally graded retrograde amnesia while leaving working memory and procedural learning intact.

Striatum

A subcortical forebrain component of the basal ganglia critical for procedural memory and motor habit formation that degenerates in Parkinson's disease due to loss of dopaminergic input from the substantia nigra.

Place Cells

Pyramidal neurons located within the hippocampus that fire selectively when an individual enters a specific geographic location within an environment.

Grid Cells

Entorhinal cortical neurons that discharge action potentials at periodic regular intervals forming a hexagonal triangular lattice to map physical space.

Hebbian Theory

A core synaptic learning model positing that repeated and persistent presynaptic activation of a postsynaptic neuron strengthens the connection between them ('cells that fire together, wire together; out of sync, lose their link').

Long-Term Potentiation (LTP)

A persistent, activity-dependent increase in synaptic strength triggered by high-frequency stimulation; involves AMPA-mediated depolarization, expulsion of $\text{Mg}^{2+}$ from NMDA channels, $\text{Ca}^{2+}$ entry, kinase activation, and insertion of additional AMPA receptors.

Long-Term Depression (LTD)

A persistent reduction in synaptic transmission efficacy induced by low-frequency stimulation; characterized by weak postsynaptic depolarization, minor $\text{Ca}^{2+}$ influx, protein phosphatase activation, and endocytosis of AMPA receptors.

Dendritic Spines

Dynamic, actin-rich micron-sized protrusions emerging from dendrites that house the postsynaptic density; their structural volumes enlarge during LTP and shrink during LTD.

Systems Consolidation

The prolonged process occurring over weeks, months, or years in which declarative memory traces initially dependent on the hippocampus are gradually transferred to and stabilized within the neocortex.