Exam 1 Flashcards
Nerve vs Tract
- Nerve= collection of axons/white matter in the PNS
- Tract= collection of axons/white matter in the CNS
Ganglia (ganglia) vs Nucleus (nuclei)
- Ganglion= collection of cell bodies in PNS
- Nucleus= collection of cell bodies in CNS
Afferent vs Efferent
- Aff= coming in toward the brain (sensory)
- Eff= going out/away from the brain (motor)
Grey Matter vs White Matter
- Grey= cell bodies, dendrites, and axon terminals
- White= axons
Central NS vs PNS
- Central= Brain and spinal cord
- Peripheral= nerves
Divisions of the PNS
- Somatic NS
- Autonomic NS
Somatic NS
- To and from skin, skeletal muscles, and joints
- VOLUNTARY control of movements
- Tactile sensations, pain, and temp
- Can also include involuntary skeletal muscle reflexes
Cranial nerves
- part of somatic division of PNS
- 12 pairs (L and R)
- Sensory and motor fxns of the head and neck
- Ex: Vagus nerve= travels through thoracic and abdominal cavities
Spinal Nerves
-Part of the somatic division of the PNS
-31 pairs (L and R)
-MIXED: contain both sensory (dorsal) and motor (ventral) fibers
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 cocegeal
Autonomic NS
- To and from visceral organs throughout body
- Involuntary control over heart rate, sweating, digestion etc
- NO VOLUNTARY CONTROL
- Divisions: Sympathetic and Parasympathetic
Sympathetic NS
- Fight or flight prep
- Uses norepinephrine
- Short 1st order neuron, long 2nd order
Parasympathetic NS
- Increases metabolic and other resources during “rest and digest”/”feed and breed”
- NTM= ACh
- Long 1st, short second neuron
Divisions of the Central Nervous System
-Cerebrum, cerebellum, brainstem, spinal cord
Spinal Cord
- Contained within the vertebral column
- Continuous with brain and peripheral nerves
- Circuits act independently from the brain to produce spinal reflexes
- Roots= contain only efferent/ventral/motor or afferent/sensory/dorsal info
- Spinal nerves=mixed
Brain stem
- Composed of midbrain, pons, medulla
- Contains= cranial nerve nuclei, sensory afferents, motor efferents, homeostatic regulatory control centers
Cerebellum
- Motor: postural balance and gait center
- R controls right side of body
- L controls left side of body
Diencephalon
- Part of cerebrum
- Thalamus= relay system of senses to and from brain
- Hypothalamus-Key center for homeostasis
- –Circadian rhythms, hunger, body temp
Telencephalon
- Part of the cerebrum
- Cerebral cortex, cerebral white matter, deep grey nuclei
Defining features of coronal section of the brain
- Superficial grey, middle white, deep grey
- Ventricles= cavity in the brain that contains CSF made by choroid plexus
Cerebral Cortex Lobe Organization
- Organized by sulci (valleys) and gyri (bumps) on surface
- Afferent and efferent pathways cross (R controls L, L controls R)
Deep Grey Nuclei
- Part of the telencephalon
- Amygdala, hippocampus, basal ganglia
Soma
- Cell body of a neuron
- Contains: Nucleus, ribosomes, ER, golgi apparatus, mitochondria
- Extensions from the soma= axon and dendrites
Variety of Neuron Shapes
- Unipolar= no dendrites, one axon
- Bipolar= 2 projections coming off of cell body
- Pseudounipolar= one axon that branches into collaterals
- Multipolar= multiple dendrites, one axon
Communication of sensory neurons, motor neurons, and interneurons
-Sensory activated by stimulus, sends info to interneurons, sends info to motor neurons
Dendrites
- Receive signals from other neurons/ outside world
- Axons of presyn cell will synapse to dendritic spines of post-syn cells
- Location of NTM receptors
Axons
- Specialized to send electrical signals from one of the cell to another
- Myelinated or unmyelinated
- –Gaps btwn myelin sheath= nodes of ranvier
Axon Terminals
- Send signal to outside world or another neuron
- Usually axon-dendritic synapse btwn 2 neurons
- –Axon of pre synapses to dendritic spines of post
The synapse
- Presynaptic neuron has synaptic vessicles-> contain NTMs
- Postsynaptic neuron has receptors
- Can also be how neurons communicated to non-neuronal tissue= neuromuscular Jon
Convergence
-Several presynaptic neurons synapse with one post-synaptic neuron
Divergence
-One presynaptic neuron synapses with many postsynaptic neurons
Glia
- Structure and support for neurons
1. Astrocytes
2. Microglia
3. Oligodendrocytes
4. Ependymal cells
5. Schwann cells
Astrocytes
- CNS
- Maintain chemical and ionic balances in environment surrounding neurons @ nodes or ranvier and @ synapses
- Send signals to surround environment (neuron guidance, survival)
Microglia
- Macrophages
- PNS and CNS
- Clean up debris after injury, programmed cell death
- *Many problems if malfunction
Oligodendrocytes
- Myelinating glia
- CNS
- Reach out and wrap myelin around axons of multiple neurons
- If damaged, multiple neurons are affected
Ependymal Cells
- Line ventricles
- Produce CSF
Schwann Cells
- Myelinating glia
- PNS
- Wrao myelin around axons of a single neurons
- –One neuron has multiple Schwann cells around its axons
Determinants of Ion Movement
- Chemical conc.
- Electrical conc.
- Permeability
Ion Channels
- Allow for passive flow of ions from high concentrations to low concentrations
- Doesn’t require energy
Active Transporters
- Actively move ions against their concentration gradient
- Requires energy
Ions in a human neuron
- Potassium- high inside cell
- Sodium- high outside cell
- Chloride- high outside cell
- Calcium-high outside cell
Resting Membrane Potential
- Largely determined by K+ because cell is most permeable to it
- RMP is -65 to -70mV
How does a neuron respond to a stimulus?
- Injecting a neg current hyperpolarizes
- Injecting a pos. current depolarizes relative to size of the current
What causes rapid depolarization in the cell?
- Na+ rushing into cell due to depolarization increasing its permeability in the cell
- –Na+ permeability is zero at rest
The flow of ions
- If current is negative- ions flowing into cell
- If current is pos- ions flowing out of cell
- Small depolarizations cause small neg currents followed by small positive currents
- –Once a cell is depolarized, cell will eventually return to resting membrane potential (-65mV)