Unit 1 and 2: Nerve Cells, Signaling, & Brain Injury
Name the structural features of a neuron and their corresponding functional zones
Soma (Cell Body): Input Site
Dendrites: Input Site
Axon Hillock: Integration Site
Axon: Conduction Segment
Presynaptic Terminal/Synapse: Output Site
Afferent vs. Efferent Signals
Afferent: Sensory signals to the brain from the body.
Efferent: Motor signals from the brain to the body.
Which cranial nerves (Name and Roman Numeral) are key for speech and swallowing?
CNs V (Trigeminal), VII (Facial), VIII (Vestibulocochlear), IX (Glossopharyngeal), X (Vagus), and XII (Hypoglossal)
What makes up the diencephalon? What are their functions?
Thalamus:
Sensory relay (except smell)***
Motor coordination
Consciousness, sleep, emotion
Hypothalamus
Homeostasis regulation
Hormonal control via the pituitary
Autonomic and emotional responses
Provide a one or two-word description of a Hemorrhagic and Ischemic stroke
Hemorrhagic: Bleed; Rupture
Ischemic: Blockage
Microglia: Immune function; phagocytosis; inflammation
Macroglia: Astrocytes: Support neurons, regulate K⁺ and glutamate, form BBB.
Oligodendrocytes: Myelinate axons in the CNS.
Schwann Cells: Myelinate axons in the PNS.
Ependymal Cells: Line ventricles.
Satellite Cells: Support PNS neurons.
What are Gray Matter and White Matter made up of?
Gray Matter: Cell bodies; organized as nuclei or cortex.
White Matter: Myelinated axons; organized into tracts or fasciculi.
Which cranial nerves have mixed (motor and sensory) functions?
Name the four lobes of the cerebrum
Frontal, Parietal, Temporal, Occipital
What are three sources of hemorrhage?
Aneurysms: Balloon-like distention on an arterial wall that can rupture and bleed
Stroke: Hemorrhagic stroke
Arterial venous malformation (AVM): Congenital tangles of arteries and veins that can rupture overtime
Describe Axonal Reaction and Wallerian Degeneration as it relates to brain injury
Axonal Reaction (Retrograde): Trying to repair; Cellular Edema occurs which triggers Nuclear Shrinking; Chromatolysis begins at axon hillock and nucleus.
Wallerian Degeneration (Anterograde): Axon that's seperated from the Soma degenerates; Myelin breakdown occurs; Protein synthesis increases to support regeneration
Describe the importance of the Neural Tube and Neural Crest
The neural tube is the structure that forms the basis of the central nervous system during early development and the neural crest forms the peripheral nervous system.
Name the three Efferent functional classifications (e.g., GSE, etc.)
General Somatic Efferents (GSE): Generalized voluntary motor (CN III, IV, VI, XII)
Special Visceral Efferents (SVE): Specific involuntary motor (CN V, VII, IX, X, XI)
General Visceral Efferents (GVE): Generalized involuntary motor (CN III, VII, IX, X)
Name the subcortical structures of the cerebrum and their functions
Basal Ganglia: Motor control and integration
Hippocampus: Long-term Memory
Amygdala: Emotional regulation; Known as a “threat indicator”
Insula: Sense of self (5th lobe)
What is the importance of the Circle of Willis (COW)?
The Circle of Willis is important because it supplies blood flow to the arteries (including the MCA, ACA, PCA). Interconnects the arterial system and lessens potential damage from clots to one area.
Describe both concentration and electrical gradients
Concentration Gradient: Movement from high to low concentration.
Electrical Gradient: Movement based on charge attraction/repulsion.
What are the 5 regions of the vertebral column and what do they innervate?
Cervical: Innervates the neck and arms
Thoracic: Innervates the upper trunk
Lumbar: Innervates the lower back and legs
Sacral: Innervates the pelvic region
Coccyx
Name the four Afferent functional classifications (e.g., GSA, etc.)
General Somatic Afferents (GSA): Generalized voluntary sensory (CN V, VII, IX, X)
General Visceral Afferents (GVA): Generalized involuntary sensory (CN IX, X)
Special Somatic Afferents (SSA): Specific voluntary sensory (CN II, VIII)
Special Visceral Afferents (SVA): Specific involuntary sensory (CN I, VII, IX, X)
What's the importance of the limbic system?
Emotion and Memory (When you smell something familiar and it reminds you of a memory)
What are three things that protect the CNS? What are the meninge layers?
1. Skull 2. Cerebrospinal fluid 3. Meninges
Menginges:
- Dura mater: outer, forms dural folds
- Arachnoid: middle, CSF circulation
- Pia mater: inner, adheres to brain surface
Outline the process of an Action Potential (Be sure to mention the Phases, PSPs, Neural integration, Ion pumps, and Ion channels)
The dendrites receive the signal and pump it into the soma (Input site), then ion channels open, causing sodium ions rush into the cell, and a concentration gradient occurs and depolarizes the cell (Depolarization), and then the axon hillock (Integration site) decides whether the signal should be sent or not (EPSP or "yes" vote outweighs IPSP or "no" vote; creates a net change in electrical potential of the neuron; NEURAL INTEGRATION) and creates the action potential at the axon hillock. Then, the neurotransmitters carry the signal down the axon (Conduction segment) to send it out through the presynaptic terminal and synapse (output site) to the next neuron (Postsynaptic cell). The neuron has to re-polarize after firing, and potassium channels open to allow for potassium to exit the cell and have stopped the sodium channels from allowing sodium ions to enter (Repolarization). However, too many potassium ions leave the cell, causing Hyperpolarization, and the ion pumps and passive ion channels of K+ and Na+ work to try to restore RMP.
The three segments of the Brainstem and their functions
Midbrain (Mesencephalon): Eye movement, visual/auditory reflexes
Pons: Facial movement, respiration, and sensory relay.
Medulla: Vital functions (respiration, cardiovascular), cranial nerves.
Briefly describe how you would test cranial nerves V, VII, IX, X, and XII
CN V: Facial sensation, corneal reflex, jaw muscle palpation
CN VII: Facial symmetry, expressions, taste test
CN IX & X: Voice quality, gag reflex, uvula position, cough strength
CN XII: Tongue movement, symmetry, strength
Where are the imporant language areas located and what do they control?
Broca's area: Posterior Inferior frontal lobe; Expressive language
Wernicke's area: Anterior Superior temporal lobe; Language Comprehension
Describe white matter organization (i.e., association, commissural, and projection fibers) and provide one example for each.
Association fibers: Connect structures within the same hemisphere (e.g., Arcuate Fasciculus)
Commissural fibers: Connect structures across opposite hemispheres (e.g., Corpus Callosum)
Projection fibers: Connect the cortex to the brainstem/spinal cord (e.g., Corona radiata)