Exam 4 Study Guide

Question 1

1. What is the difference between the CNS and the PNS? What are the subdivisions of the PNS? What are the subdivisions of the ANS?

Answer 1

CNS: integration centers- brain and spinal cord

PNS: all neuron cell bodies outside of the CNS (ganglia) and bundles of axons (nerve fibers). Sensory neurons and motor neurons act as communication lines.

Sensory PNS: somatic and visceral (organs) sensory nerve fibers
Motor PNS: motor nerve fibers. skeletal muscle. Branches into somatic and autonomic:

Somatic: conscious control. cardiac, smooth muscle, glands.

Autonomic: controls automatic processes. Branches into sympathetic and parasympathetic

Sympathetic: mobilizes NRG, fight or flight

Parasympathetic: conserves NRG, rest

Question 2

What is the difference between a neuron and a glial cells?

Answer 2

neurons: excitable (rapidly change membrane potential)- function for control- 50% of brain volume

neuroglia: support and help neurons to send and receive impulses- 99% of cells in CNS

Question 3

3. Describes the structure of a neuron

Answer 3

neurons are amitotic, cannot divide and cannot proliferate. extreme longevity, high metabolic rate (high need for O2 and glucose to produce a ton of ATP), variable shape.

Question 4

4. What are the functional and structural classifications of neurons.

Answer 4

unipolar: sensory or afferent neuron, exclusively have an axon, they lack dendrites

Bipolar: ex. olfactory cell, the ear, and also in retina. Have one dendrite and one axon, but the process can branch.

Multipolar: ex. major type, motor interneurons. Have an axon and many dendrites.

Functional classification is afferent (unipolar), efferent (multipolar), and interneuron (contained in CNS, relays info between afferent and efferent).

Question 5

astrocytes

Answer 5

CNS: astrocytes: physical support, control ECF (pick up extra neurotransmitters and ions that have been released from neurons) around neuron, surround capillaries and keep them close to neurons. have arms (cytoplasmic projections) and grab onto neurons and capillaries.

Question 6

microglia

Answer 6

CNS: microglia: thorny cytoplasmic protrusions that grab onto neurons, monitor health status of neurons, act like macrophages. If not healthy, can engulf dead cells or cellular debris. Also reach out into ECF and pick up foreign material. Phagocytosis

Question 7

ependymal cells

Answer 7

CNS: ependymal cells: line the ventricles, help produce CSF that fills ventricles. Have cilia to move CSF through ventricles. range in shape from squamous to columnar

Question 8

oligodendrocytes

Answer 8

CNS: oligodendrocytes: Have a cell body and have arms to wrap around an axon to form myelin sheath. cellular protrusions ARE the myelin sheaths around axons. Are not phagocytic and do not help regenerate.

Question 9

Satellite cells

Answer 9

satellite cells: same role as astrocytes, PNS

Question 10

Schwann cells

Answer 10

Schwann cells: similar to oligodendrocytes form the myelin sheath. entire cell wraps around axon. Phagocytic (engulf foreign material and dead cell) and help regenerate damaged neurons. PNS

Question 11

Myelin sheath

Answer 11

Acts as electrical insulator, meaning it is trying to keep the action potential contained in the myelin so to very efficient, and there is rapid transmission of action potentials. Formed by any layers of plasma/phospholipid membrane, act as insulators.

PNS: Schwann cell- layers of phospholipids and outer collar of perinuclear cytoplasm consists of Schwann cell cytoplasm and nucleus. entire cell wraps around axon

CNS: oligodendrocytes- no outer collar and only the arms/processes wrap around

Non myelinated fibers are also found in both the CNS and PNS- transmit action potentials slower

Question 12

What are the differences between a Schwann cell and an Oligodendrocyte? How is a myelin sheath produced differently in the CNS compared to the PNS? Why can a regeneration tube be formed in the PNS following an injury to an axon, but not in the CNS?

Answer 12

Schwann cells form the myelin sheath around axons in the PNS and are phagocytic and have the ability to help regenerate and repair neurons in the PNS.
Oligodendrocytes also form the myelin sheaths in the CNS, but are not phagocytic and cannot regenerate neurons.

Question 13

nodes of ranvier

Answer 13

gaps in the myelin sheath, where action potentials jump from one segment to the next.

Question 14

regeneration of axons

Answer 14

Schwann cells surround the axon, then they participate in phagocytosis to clean up the debris from severed axon, then they form a regeneration tube and secrete growth factors and cell adhesion molecules to promote regeneration of axon and hook it back together.

Question 15

multiple sclerosis

Answer 15

unregulated immune response where the body degrades the myelin sheath on the neuron. white matter has myelinated neurons, gray has non myelinated axons and cell bodies, so you can track proportions of both on an MRI. white matter is decreasing while gray matter is increasing.

Question 16

voltage

Answer 16

the measure of potential energy generated by separated electrical charges

Question 17

potential (potential difference)

Answer 17

voltage measured between two points. ex. charge difference on either side of plasma membrane because of different ion charges

Question 18

current

Answer 18

flow of electrical charge

Question 19

resistance

Answer 19

hindrance to charge flow. anything that prevents ions from moving across the plasma membrane.

Question 20

relationship between voltage and current

Answer 20

the greater the voltage, the greater the current. The greater the resistance, the smaller the current

Question 21

how do neurons function in general?

Answer 21

neurons change their membrane (action potential or nerve impulse) potential to receive info.

where neurons are passing action potentials to one another, it is known as a chemical transmission or a synapse.

Question 22

RMP (resting membrane potentials)

Answer 22

all cells have a membrane potential, or difference in ion concentration and a difference in charge. range from about -50 to -100 mv.
in non excitable cells, membrane potential cannot be changed.

excitable cells can, in order to send and receive nerve impulses. Neurons have an RMP (when not sending and receiving impulses). RMP is -70 mv. Inside of the neuron is slightly negative due to difference in ion concentrations, so the membrane is polarized. Difference in charge only exists at the plasma membrane, overall charge inside and outside of cell are neutral.

Causes: difference in ionic concentrations inside and outside the cell, and difference in membrane permeability. Permeability of membrane can be changed by channels or transporter

Question 23

Ionic differences in neurons

Answer 23

K+ and protein anions mostly inside cell.

Na+ and Cl- mostly outside cell.

Therefore, there is a gradient for K+ to diffuse out. and a gradient for Na+ to diffuse in.

Question 24

Membrane ion channels

Answer 24

Leakage channels: non gated, always allows ions to move down their concentration gradients.

Important for generating RMP, allow K+ to move down its concentration gradient, out of the cell- makes RMP to be very negative.
Also allow Na+ to move inside the cell down its concentration gradient. Leakage channels combined equal -70 mv.
Membrane is 25x more permeable to K than Na, so there 25x more K channels than Na channels.
Gated channels: chemically gated/ligand channels, voltage gated channels, mechanically gated

Question 25

What plays the biggest role in maintaining the ion gradient of -70 mv?

Answer 25

K+ channels, because there are 25x more of these channels than Na+ channels

Question 26

sodium potassium pump

Answer 26

helps to maintain resting membrane potential pumps 2 Na+ out, 3 K+ in 1. Na+ binds to

Question 27

How is a change in RMP produced?

Answer 27

1. Graded potential: a brief localized change in RMP, occurs on cell body or dendrites. +30 mv lead to action potentials Generated on a subsequent neuron after one neuron passes an action potential to it and it spreads the graded potential toward the axon hillock. Then the subsequent neuron generates an action potential at the axon hillock and that action potential spreads toward the terminal. Graded or vary in strength. Stronger graded potentials produce a greater change in RMP +30 mv might be considered strong. -50 might not be as strong Graded potentials are decremental, they decrease in strength as distance increases or they spread toward the axon hillock, so change gets smaller and smaller. - post synaptic potential- two neurons communicating at a synapse passing action potentials - receptor potential or generator potential- a receptor would be generating the graded potential 2. Action potential: a brief reversal of membrane potential followed by a return to RMP. exclusively found in excitable cells. In neurons, action potentials can only occur in the axon. Action potential phases Depolarization: membrane gets + (+30 mv) Na+ enters through voltage gated (VG) Na+ channels- positive ions flood the cell and causes positive spike Repolarization: Diving back down to RMP- go from +30 down to -70 mv, but it overshoots. K+ leaves through VG K+- loss of positive ions causes negative spike Hyperpolarization: -70 mv is overshot, membrane gets to -90 mv. K+ continues to leave through VG K+ channels while VG K+ gates slowly close sodium potassium pump helps return to normal RMP action potentials are all or none and cannot summate (can't be added together)- they are the exact same strength

Question 28

VG Na+ channels

Answer 28

have two gates, activation and inactivation gates. Allows channels to open and close very quickly. Activation gate opens first, allowing Na+ to enter, then right after, the inactivation gate slams closed to prevent more Na+ from entering. closed at rest open when axon hillock reaches threshold (sufficient stimulus) at -55 mv. -55 because graded potentials are decremental. Below -55 at axon hillock, an action potential will not be generated (subthreshold)

Question 29

VG K+ channels

Answer 29

slow to open, slow to close. They are sluggish, which is why the cell is hyper polarized during the last phase of the action potential. no activation gate closed at rest

Question 30

Threshold and action potential sequence for VG channels

Answer 30

-55 mv VG Na+ and K+ channels are triggered to open and tons of Na+ enters the cell. K+ open slightly later just as Na+ channels close. K+ now leaves the cell- repolarization +30mv to -70mv K+ are sluggish so cells hyperpolarizes -70mv to -90mv

Question 31

main players in maintaining RMP

Answer 31

K+ leakage channels Na+ leakage channels sodium potassium pump- maintaining ionic gradient- 3 Na out, 2 K+ in

Question 32

Refractory Periods

Answer 32

absolute refractory period: the period of time following stimulation during which no additional action potentials can be evoked. even if graded potentials were spreading toward the hillock, another action potential will not occur because all of the VG + Na channels are already open. reason why each action potential is a separate all or nothing even relative refractory period: when another action potential could occur, but you would need a greater than normal stimulus for action potential occur. during this period, the VG Na+ channels have closed, so it could be initiated at threshold. You would need a greater stimulus because K+ channels are still open, so to is harder to stay positive and get to threshold because you are losing positive ions.

Question 33

action potential propagation

Answer 33

in neurons, propagation is only going to occur on the axon from the axon hillock. occurs because positively charged ions are attracted to negatively charged ions in adjacent neurons. during depolarization, Na+ ions are going to be present during depolarization, so adjacent membrane will have negative ions, so they attract because Na+ ions start to move to the adjacent membrane, and brings the adjacent membrane to threshold. This opens VG Na+ channels there. But even then, membrane potentials decay with distance because of leakage channels, so AP are regenerated at every point to prevent decay of signal and spreading of AP in opposite direction. Graded potentials do not. Depolarizations follows depolarization and VG K+ are opening.

Question 34

Spreading of an action potential on myelinated vs non-myelinated fiber

Answer 34

continuous conduction when myelin is not present, AP signal will decay with distance, so it must be regenerated at every point segment to segment continuous conduction is very slow in a myelinated fiber, the sheath acts as insulation by preventing the leakage of Na and K, so signal will not decay with distance, so AP won't have to be generated at every single segment, only at the nodes of ranvier- known as saltatory conduction- AP jump from one node to the next. only get regenerated at the nodes of ranvier, and you only have VG sodium and potassium channels at the nodes. If one node gets to threshold, Na enters and current is carried to next node because of myelin sheath. extremely fast

Question 35

Propogation speed

Answer 35

myelin sheath increases speed diameter increases speed, larger axon allows for action potentials to spread much quicker, because there is more space for cellular machinery, so there are less structures obstructing the flow of ions, and less resistance to ion flow. Ex. motor neurons- myelinated and large in diameter >15-150m/sec or almost 300 mph Ex. pain afferents- small diameter and non myelination >1m/sec

Question 36

Neuronal synapses

Answer 36

point of chemical communication between two neurons. between axon and cell body, dendrites, and between an axon and hillock rarely. One neuron can receive action potentials from multiple different neurons, and can branch and synapse at different neurons. when an action arrives at the axon terminal, and triggers the opening of voltage gated Ca+ channels. Ca+ then floods the axon terminal and triggers the release of neurotransmitter via exocytosis into the synaptic cleft. The neurotransmitters then bind to chemically gated ligand gated channels on the postsynaptic neuron. ligand gated channels only open when the neurotransmitter binds. channels then open, and graded potential is formed.

Question 37

Differences between NJ channels

Answer 37

certain channels are excitatory (trying to bring postsynaptic neuron closer to threshold. Na+ will flood) or inhibitory (bringing the postsynaptic neuron farther from threshold. K+ will leave).

Question 38

Possibilities for NT

Answer 38

-diffuse away -enzymatic degradation -reuptake

Question 39

synaptic delay

Answer 39

the slowest step 0.3-0.5 msec the time it takes for a NT to diffuse across the cleft and bind to ion channels and produce a graded potential fewer synapses mean fewer synaptic delays, so less neurons are faster

Question 40

excitatory and inhibitory postsynaptic potentials

Answer 40

postsynaptic potential is a graded potential, one of the two types. both are graded potentials. excitatory (EPSP): open gated ion channels that let Na+ ions in and more K+ to leave. postsynaptic neurons depolarizes. inhibitory (IPSP): open gated ion channels that let K+ ions leave or a channel that lets Cl- enter. Cell then becomes more negative. whether or not a neuron reaches threshold is dictated by number of EPSPs or IPSPs. Must have more EPSPs to bring a neuron to threshold and generate an action potential. can summate graded potentials can also summate (action potentials cannot) temporal summation: adding together graded potentials being produced close in time (same neuron). spatial summation: adding together graded potentials that are from different neurons producing graded potentials at different points. hope is that potentials added together will produce an action potential distance from the axon hillock matters for synapses the size of a graded potential is determined by the amount of neurotransmitters released because more channels open so there is a larger change in membrane potential. current decreases with distance because of ion leakage in continuous conduction.

Question 41

Synaptic plasticity

Answer 41

when a synapse is continuously used, it will lead to greater grade potentials because it become more efficient, and more likely that the postsynaptic neuron will fire Ex. long term potentiation in hippocampus functions in learning and memory

Question 42

Acetylcholine

Answer 42

excitatory or inhibitory. excitatory in CNS and NMJ, either in ANS reduced levels can lead to Alzheimers because it causes pathways to not fire, specifically memory

Question 43

Biogenic amines

Answer 43

norepinephrine: released from motor neurons in ANS "feel good" neurotransmitter in CNS amphetimes increase release cocaine blocks removal from cleft dopamine feel good NT in CNS too little can lead to Parkinson's and too much can lead to schizophrenia

Question 44

peptides

Answer 44

endorphins and enkephalins inhibitory NT endogenous opitates (natural painkillers) runners high and childbirth

Question 45

Functional Classification of NT

Answer 45

Excitatory: wants to produce AP Inhibitory: Direct NT: **NT binds to a channel linked receptors (binds to channel and opens it) chemically gated channel, opens it, and causes ions to move.** Act quickly and produce a graded potential very efficiently and rapidly Indirect NT: act through secondary messengers, longer lasting effect because it takes more time for a graded potential to be produced. binds to a GPCR (G-protein coupled receptor) it initiates a signaling cascade in the neuron and produces a small molecule inside of the cell called a secondary messenger. **Secondary messenger binds to and opens ion channel and causes ions to move and producing a graded potential.** Detailed: Indirect NT bind to GPCR (have a G-protein coupled ) G protein is then activated and activates an enzyme called adenylate cyclase, AC catalyzes conversion of ATP to cyclic AMP. CAMP is the messenger that binds to the ion channe and causes a graded potential. Biogenic amines, peptides, gases such as nitrous oxide

Question 46

neuromodulators

Answer 46

**act on an area** in the brain rather than a single synpase when released in the brain. trying to alter the cellular properties at a synpase, such as changing the RMP of a group of neurons making them more likely or less likely to fire. mimics: SSRI's: prevents removal of serotonin (feel good) from synaptic cleft to treat depression. Block transporters that remove serotonin. cholinesterase inhibitors: act on synapses to prevent breakdown of acetylcholine for dimentia or alzheimers.

Question 47

Lateralization

Answer 47

left side: language abilities, math, logic right side: visual spacial skills, intuition, emotion, artistic skills.

Question 48

association fibers:

Answer 48

lobe to lobe, gyrus to gyrus communication

Question 49

projection fibers

Answer 49

bundles of neurons that descend/ascend to and from the spinal cord to the brain

Question 50

comissure:

Answer 50

Hemisphere to hemisphere communication corpus collasum is major commisure

Question 51

gray matter/basal nuclei

Answer 51

basal nuclei: collections of neuron cell bodies that control movement by relaying info to motor areas; filter unnecessary movement. receieve plan from motor cortedx, edit plan, and send it back to motor areas. huntingtons and parkinsons: degeneration of basal nuclei resulting in rapid uncontrolled jerking movement

Question 52

dienceohalon

Answer 52

central core of forebrain. thalamus, hypothalamus, epithalamus

Question 53

thalamus

Answer 53

2 egg shaped areas on either side of 3rd ventricle makor relay station collection of neurons recieving all sensory information for sensory neurons in PNS, sort it, edit it, and send info to cerebral cortex

Question 54

hypothalamus

Answer 54

sits right above the pituitary gland main visceral (organs) control center (ANS. control) heart rate, BP, respiration rate temperature food intake water balance sleep-wake cycle sex drive regulates anterior pituitary gland synthesizes and releases 2 hormones from posterior pituitary limbic system component: emotions

Question 55

epithalamus

Answer 55

associated with pineal gland and secretes meletonin

Question 56

midbrain

Answer 56

mesencephalon cebral aqueduct goes directly through the midbrain- connects 3rd and 4th ventricles corpora quadrigemina: largest midbrain nuclei 4 dome-like potrosions: superior colliculi- visual reflex center inferior colliculi- auditory reflex center (scream = startle) substania nigra: pigmented nuclei that produces melanin, precursor to NT dopamine functions with basal nuclei in order to control movements degeneration is associated with parkinsons cerebral peducles: tracts from large pyramidal motor neurons to effectors

Question 57

brainstem

Answer 57

arrises from mesencephalon, metencephalon, and myelencephalon acts as passageway for info connection point to peripheral NS for 10 cranial nerves

Question 58

pons

Answer 58

site of tracts (bundles of axons) that relay info from motor areas to cerebellum and from higher brain centers to the spinal cord regulates respiration, group of neurons that functions as a respiratory center, sends motor output to intercostals and maintain normal breathing rhythm

Question 59

medulla oblongotta

Answer 59

has nuclei that function for autonomic NS reflexes cardiovasucular control center respiratory control center functions for ANS reflexes: vomiting, swallowing, coughing continuous w spinal cord, so tracts relay info to higher brain

Question 60

cerebellum

Answer 60

arrises from metencephalon, but not part of brainstem coordination of muscle activity, balance, and equilibrium, recieves input about concious perception of the body in space, monitor motor output being sent to effectors, sends output to cortex and make adjustments in motor program similar to basal nuclei

Question 61

limbic system

Answer 61

emotional brain, parts of cerebral hemispheres and diencephalon

Question 62

reticular formation

Answer 62

cluster neuronetwork within brainstem (medulla, pons and midbrain) reticular activating system: relays info up to the cortex filters out sensory info- 99% of sensory info halts at reticular formation (feeling of wearing clothes)

Question 63

dura mater

Answer 63

most external meninge/membrane outer periostial layer is continuous with periosteum of skull inner meningal layer that is a true CT covering, continuous with spinal dura mater separations in membranes are called dural venus sinus- a collection point for venus blood- returns blood from brain and bring back to heart

Question 64

arachnoid mater

Answer 64

has arschnoid villi/granulations that protrude from arachoid mater into dural venus sinus- allows for CSF to empty into venus blood

Question 65

subarachnoid space

Answer 65

between arachnoid and pia mater contains CSF circulating through

Question 66

CSF

Answer 66

acts as watery cushion for protection and nourishment as its a filtrate of blood

Question 67

pia mater

Answer 67

innermost meninge, attaches directly to brain structures, site of some blood vessels that allow for production of CSF

Question 68

ventricles

Answer 68

first produces CSF by choroid plexus (hanging from the roof of ventricle- ependymnal cells and leaky capillaries from pia mater blood leaks through into ventricle) which circulates the brain and enter the subarachnoid space and enters median and appature in 4th ventricle CSF lleaves through the apperatures

Question 69

circulation of CSF

Answer 69

1. choroid plexus of each ventricle produces CSF 2. CSF flows through the ventricles and then leaves and enters the subarachnoid space via median and lateral appertures of the 4th ventricle 3. then circulates through subarachnoid space and acts as watery cushion and provides nourishment to brain structures 4. leaves the subarachnboid space and enters **dural venus sinus** via arachnoid granulation/villi so it can be absorbed into venus blood and goes back to the heart

Question 70

superior sagittal sinus

Answer 70

largest dural venus sinus

Question 71

Hydrocephalus

Answer 71

~150 mL of CSF is circulating at a time that gets turned over about every 8 hours ~500 mL is produced per day hydrocephalus occurs when CSF is produced at a faster rate than its drained and it leads to increased pressure that can damage brain structures, but infants skulls can still stretch because bones aren't fused. Treatment: insert shunt to relieve pressure into the peritoneal cavity.

Question 72

blood brain barrier

Answer 72

complex between tight junctions in endothelial cells. Between endothelial cells and astrocytes. very selective barrier that maintains stable environment by preventing chemical variations in the blood stream from reaching the brain.

Question 73

spinal cord

Answer 73

extends from foramen magnum to conus madullaris 31 pairs of spinal nerves banch off nerves existing past spinal cord are known as cauda equina has tracts or bundles of axons protected by 33 vertabrae and meninges, but dura only has the meningeal layer, not periosteal layer lumbar punctures and epidurals are done after L1, so there is no risk of hitting the spinal cord. spinal fluid may be sampled to see if infections like meningitis are present also protected by fat in the epidural space external to the dura mater that adds cushioning.

Question 74

characteristics of tracts

Answer 74

decussation: most tracts must cross at some point through the spinal cord (left and right info must cross) relay: a chain of neurons symmetry: tracts are paired to serve right and left sides of body somatotopy: spatial relationship of tracts refelcts body map whiter matter in spinal cord: has descending tracts (carrying motor output to effector organs) and ascending tracts (bring sensory input towards the brain).

Question 75

descidning and ascending tracts

Answer 75

descending tract: relaying motor output to effector organs pyramidal path: bringing motor output to skeletal muscle for precise or skilled movements lateral corticospinal- left side of brain, crosses at medulla oblongata and down to lumbar vertebrae to skeletal muscle has 3 neurons, pyramidal, inter, somatic motor neuron ventral corticospinal- right side of brain, travels down to the lumbar spinal cord, then (decosate) crosses to the left side and then synapses with a somatic motor neuron in gray matter has 2 neurons ascending tracts: in dorsal columns, tracts carry sensory info from upper and lower limbs fasiculus cuneatus: upper limb fasiculus gracilis: lower limbs both have 3 neurons in relay that are bringing info about discriminative touch main difference between two is where they originate: FC: brings info from lower limbs FG: brings info from lower limbs and first order afferent neuron: enters white matter of dorsal column all the way up the medulla of the brainstem and synapses with medullary neuron second order neuron: extends from the medulla and crosses from left to right side of the brain and synapses with a thrid order at thalamus. third order neuron: starts in nuclei of thalamus (relay station) and it relays that info to the cerebral cortex

Question 76

Reflexes

Answer 76

rapid, predictable motor responses to a stimulus unlearned, involuntary and unpremediated do not requre integration by higher brain centers (cerebral cortex does not play a role) integration centers are either spinal cord or brain stem visceral reflexes: smooth muscle, cardiac muscle, glands integration centers typically in brainstem, specifically medulla somatic reflexes: motor output is sent to skeletal muscle typically have spinal cord for integration center reflexive arc: 1. change in variable is sensed by receptor and sends it to sensory neuron 2. afferent (sensory) neuron sends it to integration center 3. integration center processes it and makes a plan 4. info is sent to efferent motor neuron 5. efferent motor neuron sends it to effectors somatic: effectors are skeletal muscle visceral: effectors are organs

Question 77

stretch reflex

Answer 77

somatic stimulus is stretch when patellar ligament is tapped receptor is muscle spindle sensory neuron brings info to spinal cord 1. synapses on somatic motor neuron 2. synapses on motor neuron telling hamstrings (antagonist) to relax 3. synapses on interneuron integration center recieves info about stretched quad and makes a plan efferent neuron goes to stretched muscle and causes a kick

Question 78

ANS

Answer 78

Differences between SNS and ANS SNS: innervate skeletal muscle (smooth, cariac muscle, glands) single somatic motor neuron from spinal cord to effectors cell bodies are exclusively in the spinal cord ACh heavily myelinated- faster AP ANS: innervates organs 2 neurons in sequence, preganglionic and postganglionic preganglionic cell body is in spinal cord, postganglionic is outside the CNS NT: norepi and ACh can be exitatory or inhibitory preganglionic are lightly myelinated, postganglionic is not at all Dual inneravtion in ANS: one is not always stimulatory or inhibitory: depends on tissue

Question 79

Sympathetic

Answer 79

dilate pupils increase heart rate dilate bronchioles stimulate liver to release glucose decreases GI tract activity preganglionic neurons in thoracic and lumbar spinal cord- short pregang, long postgang adrenal medulla- one instance where there is no postganglionic neuron

Question 80

parasympathetic

Answer 80

constrict pupils decrease heart rate constrict bronchioles increase GI activity preganglionic neurons originate in cranial and sacral regions of spinal cord-