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A&P II - Test 1
Neurophysiology & the Brain/CNS
| Question | Answer |
|---|---|
| What is the nervous system? | The body's master controlling and communicating system. |
| What are the 3 overlapping functions of the nervous system? | 1- Sensory Input 2- Integration 3- Motor Output |
| What does the Central Nervous System (CNS) consist of? | The Brain & Spinal Cord (in the dorsal cavity) |
| What does the Peripheral Nervous System (PNS) consist of? | Nerves: Spinal Nerves carry impulses to and from spinal cord & Cranial Nerves carry impulses to and from the brain. |
| What are the 2 functional subdivisions of the PNS? | 1- Sensory Division (keeps the CNS constantly informed of what's going on inside and outside of the body) 2- Motor Division (transmits impulses to effectors). |
| What are the 2 divisions of the Motor Division? | 1- Somatic Nervous System (voluntary movement) 2- Autonomic Nervous System (involuntary activity) |
| What are the 2 divisions of the Autonomic Nervous System? | 1- Sympathetic Division (activated during danger) 2- Parasympathetic Division (activated during safety) |
| What are the 4 types of Neuroglia (support cells)? | 1- Astrocytes 2- Microglial cells 3- Ependymal cells 4- Oligodendrocytes |
| Astrocytes | "star shaped," most abundant, numerous branching processes to support neurons and anchor them to capillaries (nutrient lines) |
| Microglia | small, oval-shaped, long "thorny" branching processes, phagocytic, protective role because the body's immune system is denied into the brain |
| Ependymal cells | "wrapping garment," range in shape, most have cilia, line the central cavities of the brain and spinal cord, make CSF, turn leaked interstitial fluid into CSF |
| Oligodendrocytes | Fewer branching processes than astrocytes, produce myelin sheaths around CNS nerve fibers |
| What are myelin sheaths? | Multi-layered wrappings of phospholipid surrounding most nerve fibers for insulation, increase the speed of nerve impulse transmission |
| Schwann cells | Surround and form the myelin sheaths in the PNS: wrap around and around and around the nerve cell, the last hug is called the "neurilemma." |
| What is the job of neurons? | Fire electrical impulses |
| What are the 5 special characteristics of neurons? | 1- Extreme longevity (like.. your entire life) 2- Amitotic (can't divide) 3- High Metabolic Rate (require continuous and abundant supply of oxygen and glucose) 4- Very sensitive 5- Very hard-working |
| Neuron Cell Body | Contains the usual organelles, densely packed parallel stacks of rough endoplasmic reticulum that is referred to Nissl bodies |
| What are dendrites? | The main receptive and input regions, send impulses toward the cell, enormous surface area for receiving signals from other neurons |
| What are axons? | Each neuron has a single axon, carry impulses away from the cell body toward the terminal branches, neurilemma and nodes of Ranvier |
| What happens to axons if they are cut or damaged? | They quickly decay. |
| Synaptic Knobs | At the end of terminal branches, each contains one kind of neurotransmitter in the synaptic vesicles |
| What is neurilemma necessary for? | Neuron regeneration (only in the PNS) |
| What is white matter? | Dense collections of myelinated fibers |
| What is gray matter? | Nerve cell bodies and unmyelinated fibers |
| How are neurons classified? | Structurally and functionally |
| What are the 3 structural classifications of neurons? | 1- Multipolar neurons 2- Bipolar neurons 3- Unipolar neurons |
| Multipolar neurons | Three or more branching processes; motor neurons and interneurons |
| Bipolar neurons | Two branching processes with one end a dendrite and one end an axon; special sense organs |
| Unipolar neurons | Single branching process from the cell body into proximal and distal ends; majority of sensory neurons |
| What is another word for sensory? | Afferent |
| What is another word for motor? | Efferent |
| When do chemically gated channels open? | When the appropriate neurotransmitter binds. |
| When do voltage-gated channels open? | When there are changes in the membrane potential. |
| Resting membrane potential | The potential voltage; fairly impermeable to Na+, the membrane is said to be polarized: ~ -70 mV |
| What is the sodium-potassium pump? | Ejects 3 Na+ from the cell and let's 2 K+ back into the cell, ATP-driven, stabilizes the resting membrane potential by maintaining the concentration gradients for Na+ and K+; OUR BIGGEST ACTIVITY WHILE RESTING, no need for one with a myelin sheath |
| Depolarization | Reduction in membrane potential, inside of the membrane is LESS (-) |
| Hyperpolarization | Increase in membrane potential, inside of membrane is MORE (-), takes a LOT more for stimulation |
| What does a stimulus do in regards to Na+? | Opens Na+ gates, increases Na+ permeability; stronger stimulus = more gates open |
| What are the 3 types of stimuli? | 1- Mechanical 2- Chemical (neurotransmitters) 3- Electrical |
| What are the 4 stages of Action Potential? | 1- Resting state 2- Depolarization (Na+ floods into cell) 3- Repolarization (K+ flows out of cell) 4- Hyperpolarization (K+ continues to flow out of cell) |
| What is the neuron threshold? | Critical level for the neuron to fire, different neurons have different thresholds, if you don't reach threshold then the stimulus remains localized, ~ -60mV |
| What happens when Na+ flood gates open? | The polarity flips. |
| What happens when the spike hits 30? | Na+ gates close and repolarization starts. |
| All-or-None Phenomenon | It either happens completely or it doesn't happen at all; regarding action potential |
| What is the absolute refractory period? | The time immediately following the threshold stimulus during which the neuron cannot be restimulated no matter what. |
| What is the relative refractory period? | The time immediately following the absolute refractory period during which it would take a STONG stimulus to reopen the Na+ gates. |
| What are the 2 factors that conduction velocity depends on? | 1- Axon diameter (larger axons conduct faster) 2- Degree of myelination (more myelin, saves energy= faster) |
| What is continuous conduction? | Slow type of AP propagation |
| What is saltatory conduction? | When the electrical signal jumps from node to node along the axon; 30x faster than continuous conduction |
| What are the 4 steps of Chemical Synapses? | 1- AP arrives at synaptic knob 2- Voltage-gated Ca++ channels open & Ca++ enters knob 3- Ca++ causes vesicles to release their neurotransmitters 4- Neurotransmitter diffuses across synaptic gap and binds to receptors on postsynaptic membrane |
| What would 50 excitatory neurons and 50 inhibitory neurons firing at the same time do? | Cancel each other out. |
| What are EPSPs and what do they do? | Excitatory Postsynaptic Potentials; move membrane potential toward threshold to create an action potential (short-stop) |
| What are IPSPs and what do they do? | Inhibitory Postsynaptic Potentials; move membrane potential away from threshold |
| What is temporal summation? | When one presynaptic neuron rapid-fires bursts of neurotransmitters in quick succession (ex: one soldier with 1000 bullets) |
| What is spatial summation? | When one postsynaptic neuron is stimulated by many synaptic knobs at the same time (ex: 1000 soldiers with one bullet each) |
| What neurotransmitter is released by all somatic neurons? | Acetylcholine (ACh) |
| What are 2 "feel good" neurotransmitters? | Norepinephrine, Dopamine |
| What is the neurotransmitter involved in sleep, appetite, nausea, migraine headaches, and regulation of mood? | Serotonin |
| What are the 2 functional classifications of neurons? | 1- Excitatory (cause depolarization) 2- Inhibitory (cause hyperpolarization) |
| What are the 4 sections of the brain? | 1- Cerebrum 2- Diencephalon (Thalamus & Hypothalamus) 3- Cerebellum 4- Brain Stem (Midbrain, Pons, Medulla Oblongata) |
| What are the 4 major lobes of the brain? | 1- Frontal 2- Parietal 3- Occipital 4- Temporal |
| What are the Frontal and Parietal lobes separated by? | The central sulcus |
| What is the "5th" major lobe of the brain? | The Insula (deep in the lateral fissure, coats the thalamus) |
| What are the 5 parts of the cerebrum? | 1- R lateral fissure 2- L lateral fissure 3- central sulcus 4- precentral gyrus 5- postcentral gyrus |
| What kind of matter is the cerebral cortex? | Thin layer of gray matter |
| What is the primary motor cortex and where is it? | Controls all voluntary movement; in the precentral gyrus of the frontal lobe of each hemisphere |
| What is the Pyramidal System and what does it include? | The Pyramids are long axon nerve fibers from the precentral gyrus that you can see cross on the medulla oblongata on their way to the spinal cord; The Pyramidal System initiates all voluntary movements and damage to it causes paralysis |
| What are the 2 parts of the Extrapyramidal System (subconscious)? | 1- Basal ganglia (inhibit signals) 2- Cerebellum (coordinates muscle groups/muscle memory) |
| What is decussation of the Pyramids? | The crossing of the fibers on the medulla oblongata. |
| What do commissures do? | Connect corresponding gray areas of the two hemispheres to enable them to function as a whole |
| What is the largest commissure? | The corpus callosum (in the longitudinal fissure) |
| What do association fibers do? | Connect different parts of the same hemisphere |
| What do projection fibers do? | Connect the cortex to the rest of the nervous system |
| What do basal ganglia do? What is a disorder of basal ganglia? | They inhibit unnecessary movement; Parkinson's disease |
| What are the 2 parts of the diencephalon? | 1- Thalamus 2- Hypothalamus |
| What caps the brain stem? | The hypothalamus |
| What are some characteristics of being "Left-Brained?" | Logical, linear thought, mathematical, detail-oriented, language, memorization, R-handed |
| What are some characteristics of being "Right-Brained?" | Intuitive, Holistic thought (big picture), Visualization ("mind's eye"), Musical "feel," L-handed |
| What does the epithalamus house? | The pineal gland, which secretes the hormone melatonin |
| Where is the midbrain located? | Between the diencephalon and the pons |
| What is the pons and where is it? | Mainly conduction tracts; between the medulla oblongata and the brainstem |
| Where is the medulla oblongata? | Blends into the spinal cord at the level of the foramen magnum of the skull |
| What are the 4 things protecting the brain? | 1- The Skull (bone) 2- The Meninges (membranes) 3- Cerebrospinal Fluid 4- The Blood-Brain Barrier |
| What are the meninges? | Three connective tissue membranes that form a continuous sac over the CNS; dura mater, arachnoid mater, and pia mater |
| What is dura mater? | "tough mother," the strongest meninx, two-layered fibrous connective tissue |
| What do the dural venous sinuses do? | Collect venous blood from the brain and direct it to the internal jugular veins |
| What are the dural septa? | Flat partitions that divide the cranial cavity and limit excessive movement of the brain |
| What are the 2 dural septa you need to know? | 1- Falx cerebri (sickle-shaped, into the longitudinal fissure between the hemispheres) 2- Tentorium cerebelli (a "tent" over the cerebellum, into the transverse fissure between the hemispheres) |
| What is arachnoid mater? | The middle meninx, loose brain covering that never dips into the sulci, looks like a dense spider web with weblike extensions to secure it to the pia mater, filled with CSF, contains the largest blood vessels that are poorly protected |
| What is pia mater? | "gentle mother," thin connective tissue but VERY vascular, clings to the brain like cellophane |
| What is cerebrospinal fluid and what does it do? | A liquid cushion in and around the brain, reduces brain weight by 97%, protects the CNS from trauma, rich blood supply that nourishes the brain, carries some electrical signals |
| What is the blood-brain barrier? | The brain's protective mechanism; astrocytes and endothelial cells that form tight junction to not let certain things going on in the body into the brain (selective), ineffective against certain meds, fats, O2, CO2, etc; absent in some areas of the brain |
| What is the spinal cord? | Two-way conduction pathway to and from the brain |
| How many layers does the spinal dura mater have? | One |
| What is in the epidural space and where is it? | Adipose and veins, between the bony vertebrae and the spinal dura mater |
| Where does the spinal cord typically end? | Between L1 and L2 |
| What is the gray commissure in a spinal root? | A crossbar of gray matter than encloses the central canal. |
| What are ganglia? | Groups of neuron cell bodies in the PNS; GRAY matter (unmyelinated) |
| What are nuclei? | Groups of neuron cell bodies in the CNS; GRAY matter (unmyelinated) |
| Where are the large gray horns? | T1 - L2 |
| Where are the small gray horns? | S1 - S4 |
| What are white columns mostly made up of? | Projection tracts |
| What is a tract? | A bundle of nerve fibers in the CNS |
| Which way do commissural tracts connect? | Right to left (ie: corpus callosum) |
| Where do association tracts connect? | Within one side of the body |
| What is a nerve and what are most of them? | A bundle of nerve fibers in the PNS; most are white matter ATTACHED to the CNS |
| What are the 3 types of nerves? | 1- Sensory 2- Motor 3- Mixed (2-way communication of sensory and motor) |
| What are projection tracts and where are they? | Ascending and descending pathways of Mixed neurons; in white matter |
| What is gray matter? What are the 4 zones? | Groups of neuron cell bodies, dendrites, and unmyelinated axons; autonomic motor, autonomic sensory, somatic motor, somatic sensory |
| Where does synapsing always happen? | In gray matter |
| What is white matter? | Bundles of myelinated nerve fibers (axons); NO SYNAPSING |
| Where are First-order neurons and what do they do? | In the dorsal root ganglia; conduct impulses from sensory receptors to the CNS |
| Where are Second-order neurons and what do they do? | In the lateral gray horns of the spinal cord (white matter); transmit impulses to the thalamus |
| Where are Third-order neurons and what do they do? | In the thalamus; replay impulses to the somatosensory cortex of the cerebrum |
| At what order is PAIN detected? at what level is pain located? | Detected by Second-order neurons; located by Third-order neurons |
| What kind of nerve is every spinal nerve? | Mixed nerve |
| How many pairs of cervical nerves are there? | 8 (7 vertebrae) |
| How many pairs of thoracic nerves are there? | 12 |
| How many pairs of lumbar nerves are there? | 5 |
| How many pairs of sacral nerves are there? | 5 |
| How many pairs of coccygeal nerves are there? | 1 |
| What do you call the holes in the vertebrae? | Intervertebral foramena |
| What are the 5 parts of the Reflex Arc? | 1- Receptor 2- Sensory neuron 3- Integration center (reflex) 4- Motor neuron 5- Effector |
| What are the 2 types of reflexes? | 1- Somatic reflexes 2- Autonomic reflexes |
| What is an ipsilateral reflex? | One that stays on one side of the body (ex: withdrawal reflex of hand) |
| What is a contralateral reflex? | One that uses both sides of the body (ex: stepping off of a tack) |
Created by:
cestutes