Final Exam:Final Flashcards
What are the divisions of the Nervous System?
Central Nervous System (CNS) and Peripheral Nervous system (PNS)
What are the components of the CNS?
Brain (85 billion neurons) Spinal Cord (100 billion neurons)
What are the functions of the CNS?
process incoming sensory info; source of thoughts; emotions; memories; stimulate muscle contraction and glandular secretion.
What are the components of the PNS?
Nerves- bundles of hundreds to thousands of axons; 12 pairs cranial; 31 pairs spinal cord.
Ganglia
small masses of nervous tissue primarily nerve cell bodies; outside brain and cord.
Enteric plexus
extensive network of neurons in walls of organs of GI tract; regulate digestion.
Sensory receptions
monitors change in internal/external environment.
What are the divisions of the PNS?
Somatic NS and Autonomic NS
Somatic NS
sensory neurons take info from somatic receptors _ CNS; motor neurons conduct impulses from CNS _ skeletal mm only. (voluntary)
Autonomic NS
info flows from sensory receptors in visceral organs _ CNS; motor neurons conduct impulses from CNS _ smooth and cardiac mm and glands (involuntary)
What are the divisions of the motor portion of the ANS?
sympathetic; parasympathetic
Sympathetic
fight or flight
Parasympathetic
rest and digest
Enteric NS
brain of the gut - over 1 mil neurons in plexuses extend throughout GI tract.
What is nervious tissue composed of?
Neurons and Neuroglia.
Neurons
form complex processing network in brain and spinal cord; connect all regions of body to the brain and spinal cord; highly specialized cells; can reach great lengths; unique functions (sensing; thinking; remembering; control muscle activity; regulate gland secretions. Unable to undergo cell division (mitosis)
Neuroglia
smaller; greatly outnumber neurons; support; nourish; protect and maintain interstitial fluid that bathe neurons; can continue to divide throughout lifetime. _ Glue that holds nervous tissues together._
Cell Body
contains nucleus cytoplasm; with typical organelles; also free ribosomes and rough ER ( nissl bodies)
Axon
propagate nerve impulses toward another neuron; muscle fiber or gland.
Dendrite
receiving portion of neuron.
Neurofibrils
bundles of intermediate filaments provide cell shape and support.
Microtubles
assist in moving materials between cell body and axon.
Lipofuscin
yellow/brown clumps of pigmentin cytoplasm of aging neurons.
Nerve Fiber
any neuronal process that emerges from cell body of a neuron.
Axon hillock
cone shaped elevation where cell body joins axon.
Axoplasm
cytoplasm of an axon.
Axolemma
plasma membrane of an axon.
Axon Terminal
branching off of the axon collateral into fine processes.
Synapse
site of communication between 2 neurons of neuron and effector cell.
Synaptic end bulbs
swellings at tips of axon terminals
Synaptic vesicles
tiny membrane enclosed sacs store chemicals.
Neurotransmitters
chemical/molecule released from synaptic vesicle excites or inhibits another neuron; m fiber; or gland.
Describe slow axonal transport
1-5 mm per day; one direction; axoplasm from cell body toward axon terminals; supplies new axoplasm to developing axons; replenishes I for growing neurons.
Describe fast axonal transport
200-400 mm/day; proteins function as motors to move substances along surfaces of the microtubules of neurons cytoskeleton. BOTH directions- anterograde (forward cell body_axon terminals) Retrograde (backward; materials from axon terminals_cell body) Substances: trophic chemicals (nerve growth factor); harmful agents (tetanus toxin; viruses that cause rabies; herpes simplex; and polio)
What are the structural classifications of neurons?
multipolar; bipolar; unipolar; purkinji cells; and pyrmidal cells
What are the funtional classifications of neurons?
sensory; motor; interneurons
Multipolar neurons
several dendrites 1 axons; mostly in brain and cord and all motor neurons.
Bipolar neurons
1 main dendrite 1 axon; in retina; inner ear; olfactory area of brain.
Unipolar neurons
dendrites and 1 axon; fused form continuous process emerges from cell body AKA pseudounipolar; most act as sensory receptors that detect stimulus.
Purkinji cells
in cerebellum.
Pyrimdal cells
found in cerebral cortex.
Sensory function
afferent - receptors at distal ends of cells; most unipolar.
Motor function
efferent -Conveys AP away from CNS to effectors; multipolar.
Interneurons function
AKA association nerves; mainly in CNS between sensory and motor neurons; most multipolar.
What are the types of neuroglia?
Astrocytes; oligodendrocytes; microglia; ependymal cells; shwann cells; satellite cells
Nueroglia
glue that holds nervous tissue together; make up ¬ volume of CNS; do not generate/propagate AP; can multiply and divide in mature nervous system.
Astrocytes
star shaped; many processes; supporting cells for neurons; create blood brain barrier between blood and interstitial fluid; secrete chemicals in embryo to regulate growth; maintain appropriate chemical environment for generation of nerve impulse; influencing formation of neural synapses.
Oligodendrocytes
smaller than astrocytes fewer processes; processes form myelin sheaths around CNS axons.
Microglia
small cells slender processes spine like projections; phagocytes.
Ependymal cells
cuboidal to columnar; microvilli and cilia; line ventricles of brain and central canal of spinal cord; circulation of CSF; blood CSF fluid barrier.
Schwann cells
in PNS; around PNS axons; form myelin sheaths around axons; axon regeneration.
Satelite cells
around cells bodies of neurons on PNS ganglia; structural support; regulate exchange of material between neuronal cell bodies and interstitial fluid.
What is myelin comprised of?
multi-layered protein and lipid covering
What are the similarities and differences between schwann cells and oligodendrocytes
Schwann cells form myelin sheaths around axons in the PNS; have ganglion cell bodies (clusters) and nerves (bundle of axons in PNS) contain neurolemma (only on axons of PNS); Oligodendrocytes processes form myelin sheaths around axons in the CNS; have nucleus cell bodies and tracts; no neurolemma. Both have nodes of Ranvier (gaps in sheaths) but less numerous in oligodendrocytes.
Compare and contrast clusters of neuronal cell bodies. What are they? Where are they found?
Ganglion- cluster of cell bodies in the PNS associated with spinal/cranial nerves; found in Schwann cells.; Nucleus- cluster in bodies of CNS; found in oligodendrocytes.
Know the difference between white and grey matter. Know where they will be found.
White matter- primarily mylenated axons.; Gray matter- primarily cell bodies dendrites; unmylenated axons; axon terminals and neuroglia; appears gray due nissl bodies and lack of myelin.; Spinal cord- white matter outside; gray inside. Brain- gray outside; white outside.
Where is white matter found?
outside
Where is grey matter found?
inside
What is the difference between an upper and lower motor neuron?
Upper motor neuron- a motor neuron that synapses with a lower motor neuron farther down in the CNS as opposed to the brain. Lower Motor Neuron- motor neuron that directly supplies skeletal muscle fibers.
What is resting membrane potential?
the voltage (charge) difference across the cell membrane when the cell is at rest. Its created by a small build-up of negative ions in the cytosol along the inside surface of the membrane and an equal build up of positive ions in the ECF along the outside surface of the membrane.
What is the typical RMP of a nueron
.-70 mV.
What are the factors that determine resting membrane potential?
3 factors-unequal distribution of ions in the ECF/cytosol; inability of most cytosolic anions to leave the cell; electrogenic nature of the Na+ -K+ ATPase_s.
What are the four types of a ion channel?
Leak channels; ligand gated channels; mechanically gated channels; and voltage gated channels
Leak channels
randomly alternate between open and closed positions; nearly all cells.
Ligand gated channels
opens and closes in response to binding of a ligand (chemical) stimulus; dendrites of some sensory neurons such as pain receptors.
Mechanically gated channels
opens or closes in response to mechanical stimulation in the form of stretching of internal organs; touch/pressure receptors in skin.
Voltage gated channels
opens in response to a change in membrane potential (voltage) all neurons.
What is a graded potential?
small deviation from resting membrane potential that makes a membrane either more polarized (inside more negative) or less polarized (inside less negative).
Hyperpolarizing GP
response makes inside more negative.
Depolarizing GP
response makes membrane less polarized.
What is the sequence of an action potential?
- Depolarization- reversal of the membrane polarization from -70mV to +30mV 2. Repolarization- recovery of the resting membrane potential from +30mV to -70mV 3. Absolute refractory period- during first part of this period; no matter how strong an impulse is another impulse cannot be stimulated. 4. Relative refractory period- a little later; an AP can be generated if it is larger than normal stimulus.”
What is salutatory conduction?
Action potentials can travel long distances w/ out getting small (unlike graded potentials) nerve impulses are able to jump from one node of Ranvier to another along a mylenated axon. This allows for faster than normal; continuous conduction and is called salutatory conduction.
What are the factors that affect the speed of propagation?
- Amount of myelination; myelination= faster speed 2. Axon diameter; larger = faster speed 3. Temperature; Cooler = slower speeds”
What are the classifications of nerve fibers?
A fibers; B fibers; and C fibers
A fibers
largest diameter; +myelination; 27-290 mph; sensory neurons associated with touch; pressure; pain and temp.
B fibers
medium diameter; +myelination; 34 mph; sensory nerve impulse from viscera to brain and spinal cord; autonomic nervous system.
C fibers
smallest diameter; all unmyelinated; 1-4 mph. Conduct some sensory (pain and temp) autonomic fibers that extend from autonomic ganglia to stimulated heart; smooth mm and glands.
What are the classifications of neurotransmitter recepters?
Iontropic recepters; and metabotropic receptors
What neurotransmitter interacts with an ionotropic receptor?
ligand-gated channel
What neurotransmitter interacts with an metabotropic receptor?
contains NT binding site but lacks an ion channel
What are the effects of the specific neurotransmitters.
Some NT are excitatory at some synapses and inhibitory at others; depends on the structure of the NT receptor it binds to. Ach can bind to ionotropic receptors containing cation channels and generate EPSP in the postsynaptic cell. Some inhibitory synapses Ach binds to metabotropic receptors couples to G proteins that open K+ channels_IPSP.
How is a nuerotransmitter removed from the synaptic cleft; name the different ways?
NT removed in 3 ways: 1. Diffusion (diffuse away from cleft); 2. Enzymatic degradation (ex. Acethycholinesterase) 3. Uptake by cells (active transport back into neuron by membrane proteins.”
What is summation of a potential?
process by which graded potentials add together. The greater summation of EPSP_s the greater the chance that threshold will be reached.
What is the difference between spatial and temporal summation?
Spatial Summation- summation of postsynaptic potentials in response to stimuli that occur at different locations in the membrane of a postsynaptic cell at the same time.
What are the names of the enzymes that breaks down epinephrine norepinephrine and dopamine?
All are broken down by same enzyme catechol-omethyltransferase (COMT) and monoamine oxidase (MAO)
What are the small molecule neurotransmitters?
Acetycholine; Amino acids; bigenic amines; ATP and other purines; Nitric oxide; and carbon monoxide
Acetycholine basic function
excitatory and inhibitory.
Amino acids basic function
glutamine and aspartate; inhibitory- GABA; glycine
Bigenic amines basic function
norephinepherine (arousal/waking from sleep); epinephrine; dopamine (emotional response; addictive behaviors)
ATP and other purines basic function
excitatory in both PNS and CNS
Nitric oxide basic function
free radical; released by endothelial cells to cause vasodilation of blood vessels (Viagra)
Cabon monoxide basic function
formed as needed; may protect against excess neuronal activity.
What are neuropeptides?
3-40 amino acids linked by peptide bonds; CNS and PNS; excitatory and inhibitory; bind to metabotropic receptors; formed in the neuron cell body packaged into vesicles and transported to axons.
Name 3 naturally occurring neuropeptides.
Enkephalins; opioids; substance P
Enkephalins function
potent natural analgesic; 200x more potent than morphine.
Opioids function
endorphins/dynorphins-thought to be case with acupuncture.
Substance P function
enhances perception of pain; counters effects of nerve damaging chemicals; potential treatment for nerve degeneration.
Plasticity
ability to change based on experience. In NS individual neurons can undergo change.
Regeneration
ability to replicate or repair themselves.
Neurogenesis
the birth of new neurons from undifferentiated stem cells.
Epidermal growth factor
hormone like protein that stimulates cells taken from the brains of adult mice to proliferate into both neurons and astrocytes; also found important in wound healing and tissue regeneration.
Which part of the brain can undergo neurogensis?
Hippocampus (site crucial for learning)
Why is the rest of the brain and spinal cord not able to undergo neurogenesis?
Nearly complete lack of neurogenesis in other regions of the brain and spinal cord 2 factors: 1. Inhibitory influences from neuroglia- CNS myelin found on oligodendrocytes inhibits regeneration of neurons. 2. Absence of growth stimulating cues- present during fetal development.”
What is the cause of MS?
autoimmune disease leading to progressive destruction of the myelin sheaths surrounding neurons in the CNS; Myelin deteriorates to sclerosis (hardened scars or plaques) genetic susceptibility; environmental exposure; possibly viral (herpes);
What are the signs/symptoms of MS?
feeling heaviness/weakness in muscles; abnormal sensations; and double vision.
What is the most common form of MS?
relapsing remitting; appears in early adulthood; attack followed by period of remission in which symptoms temporarily disappear; attack every year or two.
Who is affected by MS?
Females 2:1; white; ages 20-40 yrs.
What is the treatment for MS?
beta-interferon; lengthens time between relapse; decrease severity.
What is Guillian-Barre’ Syndrome?
acute demyelinating disorder in which macrophages strip myelin from axons in the PNS.
What is the cause of Guillian-Barre’ Syndrome?
likely the result of the immune system response to a bacterial infection.
What is the manifestations of Guillian-Barre’ syndrome?
Ascending paralysis; most common cause of acute paralysis.
What is giloma?
a malignant tumor affecting the brain or spine.
What is nueroblastoma?
malignant tumor consisting of immature nerve cells (neuroblasts); most common in abdomen in adrenal glands; rare but most common tumor in infants.
What is neuropathy?
disorder that affects the nervous system; particularly a cranial or spinal nerve; caused by b12 deficiency or diabetes.
What are the brain vesicles that give rise to adult structures?
Telencephalon; diencephalon; mesencephalon; metencephalon; myeloencephalon
Telencephalon
cerebrum and lateral ventricles
Diencephalon
thalamus; hypothalamus; epithalamus; third ventricle
Mesencephalon
midbrain; cerebral aquaduct
Metencephalon
pons; cerebellum; upper part of 4th ventricle
Myelencephalon
medulla oblongata; lower part of the 4th ventricle
What are the major parts of the brain?
brainstem; cerebellum; diencephalon; cerebrum
What are the major parts of the brain stem?
pons; midbrain; medulla oblongata
What are meninges?
Meninges are the protective covering of the brain and spinal cord.
What is the general difference between cranial and spinal meninges?
Cranial meninges- surround and protect brain; Spinal meninges- surround and protect the spinal cord
Name the layers of the meninges
Dura mater; arachnoid mater; and Pia mater
Dura mater
outer layer; 2 layers fused together- periosteal (outermost); meningeal layer (internal)
Arachnoid mater
middle; lace like
Pia mater
inner most; contains blood vessels
Is there epidural space around the brain?
No epidural space around brain.
Name the 3 extensions of dura mater that separate the different parts of the brain.
Falx cerebri; falx cerebelli; and tentorium cerebelli
Falx cerebri
separate L/R cerebral hemispheres
Falx cerebelli
separate hemispheres of cerebellum
Tentorium cerebellum
separate cerebrum & cerebellum
What are the general structures of the cerebrum?
Gyri; sulci; fissures
Gyri
elevated ridges
Sulci
depressions; central; lateral; parieto-occipital; insula
Fissures
Big depressions; longitudinal fissure; lateral fissure; transverse fissure
What is the corpus callosum? What is it composed of?
Corpus callosum- large bundle of white matter and axons that internally connects the 2 cerebral hemispheres
Name the lobes of the cerebrum
Frontal; parietal; temporal; and occipital
Function of frontal lobe
motor strip location; impulsivity; short-term memory; emotion; voluntary movement; social functioning; creativity; expressive language.
Function of parietal lobe
sensory strip location; perception; touch (pain & temperature); ability to draw; reading and writing; calculations.
Function of temporal lobe
hearing; long term memory; verbal and written recognition memory; receptive memory; music; initiation of verbal.
Function of occipital lobe
perception; vision
What are the types of white matter found in the cerebral white matter?
Types of fibers: Association; commissural; and projection.
Basal ganglia
cerebral nuclei; several groups of paired nuclei w/in the white matter of the cerebrum; interconnected by many nerve fibers; receive numerous inputs from cerebral cortex; thalamus; and hypothalamus
Basal ganglia function
ontrol of large; learned; semi-voluntary skeletal muscle movements; such as swing arms when walking; laughing; and regulation of muscle tone.
Functions of cerebellum
coordinates skilled movements; regulates posture and balance.
Charateristics of cerebellum
second largest part; consist of L and R hemispheres-connected by vermis; covered in cerebellar cortex; consists of folia instead of gyri; each hemisphere divided into anterior and posterior lobes by primary fissure.
What is the tentorium cerebelli?
The cerebellum is separated from the cerebrum by a fold of dura known as the tentorium cerebelli
What is the thalamus?
oval structure above the midbrain; forming 4/5 diencephalon; consists of paired masses of gray matter organized into nuclei that form lateral walls of the 3rd ventricle.
Why is the thalmus significant?
It is the principle relay station for sensory impulses (except smell) that reach the cerebral cortex from the spinal cord; brain stem; and other parts of the cerebrum.
What is the hypothalamus?
small portion of the diencephalon 1/5; lies below the thalamus; primarily gray matter dividing into pairs of nuclei; each pair responsible for the control of particular homeostatic function;
What is the general function of the hypothalmus?
1 of the major controllers of homeostasis
What are the specific functions of the hypothalmus?
- Integration between nervous and endocrine systems 2. Control of autonomic NS 3. Regulation of rage and aggression 4. Regulation of body temp 5. Regulation of food intake 6. Regulation of thirst 7. Regulation of sleep-wake patterns 8. Regulation of sex drive”
What are ventricles?
holes in the brain that are responsible for the circulation of CSF
Trace the flow of CSF through the brain/spinal cord by way of the canals and ventricles. Start at the lateral ventricle.
Lateral- found in each cerebral hemisphere ; Third- in diencephalon; Fourth- in between pons and cerebellum; connects central canal and spinal cord”
What is CSF?
clear fluid mostly water; protects brain and spinal cord from chemical and physical injury.
What substances can be found in CSF?
Carries glucose; oxygen; electrolytes; cations/anions; proteins and urea.
Function of CSF?
mechanical protection (shock absorbing medium); homeostatic (ph affects blood flow); circulation (exchange of nutrients and waste products)
Where is CSF resorbed?
Majority formed in Choroid plexus; and resorbed at arachnoid granulations.
What is hydrocephalus?
infants failure to resorb CSF; fluid expands and crushes the brain.
What is the blood brain barrier?
capillaries of CNS less permeable to substances; endothelial cells linked by tight junctions; astrocytes cover capillary surface.
What substances are allowed through this barrier?
Only lipid soluble compounds diffuse into CNS; all others have to undergo active transport by astrocytes.
What kinds of things can break down this barrier?
Inflammation; infection; cancer; immune disorders can break down barrier.
What is the reticular activating system (RAS)?
sensory axons that ascend to the cerebral cortex traveling through the thalamus
What is the function of RAS?
visual and auditory stimuli; mental activities; consciousness; prevents sensory overload.
What is the result of inactivation of RAS?
Inactivation when asleep or a coma.
What is the limbric system?
a functional region rather than anatomical; between the cerebrum and diencephalon.
Function of limbric system
establishes emotional states and drives; links conscious functions of the brain stem; facilitates memory storage and retrieval.
What are the special regions of the limbric system?
Amygdala; hippocampus; cingulate gyrus
Amygdala
“fight or flight - initiates fear response; links emotion w/memory.
Hippocampus
memory and learning
Cingulate gyrus
expressing emotions via gestures and resolves mental conflicts
What are the integrative centers of the brain?
Wernicke_s Area; Broca_s Area; Pre-frontal cortex.
Wernicke_s area
general interpretive area; center of left hemisphere; gives meaning to auditory and visual cues
Broca_s area
_speech center_; left hemisphere superior to lateral; coordinates motor controls for speech
Prefrontal cortex
anterior frontal lobes; prediction; estimation; and related emotion
Basic function of left hemisphere
language; math; logic
Basic function of right hemisphere
interprets sensory info; generate emotion; spatial visualization Each hemisphere sends info to the opposite side of the body. Hemispheres communicate for whole thought; if corpus callosum is cut they will work independently from each other; this has been used for treatment for surgeries.”
What are the functional areas of the cerebra cortex?
Sensory; Motor; and Association areas
Sensory areas
receive sensory input; and integrate and interpret sensations
Motor areas
contain neuronal cells bodies; origin for practically all motor activities
Association areas
make up several main areas that serve to connect the sensory and motor areas; integrative and interpretive functions
Cerebrovascular accident
stroke; loss of blood supply to the brain; neuronal death occurs within minutes.
Name the cranial nerves
Olfactory I; Optic II; Oculomotor III; Trochlear IV; Abducent VI; Trigeminal V; Motor muscles of mastification (6); Facial Nerve (VII); Intermediate Nerve; Vestibulocochlear VIII; Glossopharyngeal IX; Vagus X; Accessory XI; Hypoglossal XII
Olfactory I
sensory
Optic II
sensory
Oculomotor III
Motor
Trochlear IV
Motor
Abducent VI
Motor
Trigeminal V
Both
Facial Nerve VII
Motor
Intermediate Nerve
Both
Vestibulocochlear VIII
Sensory
Glossopharyngeal IX
Both
Vagus X
Both
Acessory XI
Motor
Hypoglossal XII
Motor
Function of Trigeminal V
sensory to the face; motor for chewing
Function of Facial VII
motor to the mouth
What nerves move the eyeball?
CNIII; IV;VI
Function of Olfactory CN I?
smell
Function of Vagus X?
sensory- aortic sinus and body related to blood pressure control; mucousa of respiratory and digestive systems Motor-muscles of the bronchial tree; digestive tract; pancreas; liver; and glands of the GI system.”
