The Nervous System

Front 1

3 main functions of the nervous system

Back 1

1-sensory
2-integrative
3-motor

Front 2

types of channels @ ea. part of the neuron

Back 2

1. @ the dendrites & cell body: chemically gated channels

2. along the axon: voltage-gated Na+ and K+ channels

3. @ axon terminals/end bulbs: voltage-gated Ca2+ channels

Front 3

sensory neurons

Back 3

aka afferent (upward); carry info from lower to higher levels in the SC or from cranial or spinal nerves to the brain and SC

Front 4

interneurons

Back 4

nexus b/w neurons, their axons extend for short distances contacting neurons in brain, SC or ganglia

Front 5

motor neurons

Back 5

aka efferent; carry info from the brain toward the SC and/or from the brain and SC to cranial nerves and spinal nerves

Front 6

synapse

Back 6

junction b/w 2 neurons or b/w a neuron and an effector cell
- includes presynaptic (sends signal) and postsynaptic (receives impulse) terminals

Front 7

gap junction

Back 7

electrical synapse

Front 8

synaptic cleft

Back 8

chemical synapse

Front 9

electrical synapse characteristics

Back 9

-ionic current spread to next cell thru gap junctions

-faster, 2-way transmission [pre-> post or post->pre]

-capable of synchronizing groups of neurons

-ex: heart

Front 10

chemical synapse characteristics

Back 10

- 1-way transmission from pre to postsynaptic neuron

-neurons/cells involved do not touch (separated by synaptic cleft)

-there are more of these types of synapses

-can't synchronize

Front 11

events in a chemical synapse

Back 11

1. nerve impulse arrives
2. nerve impulse causes a change in impulse/ opens voltage-gated calcium channels
3. exocytosis of neurotransmitter ((ca2+ rushes in, ca2+ causes vesicles to dump their contents into synaptic cleft))
4. CA2+ causes vesicles 2 dump their contents (neurotransmitters) into synaptic cleft
5. neurotransmitter binds to the specific channels
6. na, k gates open, Na+ rushes in
7. post-synaptic potential: if there's enough Na+ to create nerve impulse

Front 12

botulinum toxin

Back 12

blks release of neurotransmitter at the NMJ

muscle contraction can't occur

Front 13

curare

Back 13

plant poison from poison arrows

causes muscle paralysis

blocks ACh receptors

used to relax muscles during surgery

Front 14

neurotransmitter effects can be modified via

Back 14

-synthesis
-release
-removal
-receptor sight (blocked or activated)

Front 15

common neurotransmitters

Back 15

ACh
AAs
Amines (Ep, Norep, Dop, Ser)
ATP
NO
Neuropeptides (endorphins,etc)

Front 16

Divisions of NS

Back 16

2 Main: Central & Peripheral

CentraL: B & SC

Peripheral: Somatic & Autonomic

Autonomic: Sympathetic, Parasympathetic, Enteric

Front 17

Tracts of the SC

Back 17

are highways for sensory &motor info

sensory/ascending ____s: conduct nerve impulses toward the brain

motor/descending ____s: conduct impulses down the cord

Sometimes ____s receive & integrate incoming & outgoing info

Front 18

Somatic NS

Back 18

sensory neurons to CNS & motor neurons to skeletal muscle

1 neuron in pathway

motor neurons innervate SKELETAL muscle to produce: conscious, voluntary mvmts

effect of a motor neuron is always excitation (to stop, withdraw excitation)

Front 19

Autonomic NS

Back 19

operates via REFLEX ARCS

2 neurons in pathway (pre and postganglionic)
- pre- myelinated
- post- unmyelinated

continual flow of sensory input from receptors in organs & motor output to the same organs
[constant info bk and frth]

not aware of responses (control center is in lower regions of brain)

HYPOTHALAMUS is major control center
--> autonomic tone: regs balance b/w symp and parasymp activity

Dual innervation (input from symp and parasymp) of most organs

Front 20

Hypothalamic Control of ANS

Back 20

input: emotions and visceral sensory info (smell,taste,temp, osmolarity of blood,etc)

output: to nuclei in brainstem & SC

post&lat: control SYMPNS to inc <3rate, inhibit GI tract, inc temp (deal w/stress)

med&ant: control PARASYMNS to dec <3rate, lower BP, inc GI tract secretion & mobility

Front 21

Adrenergic

Back 21

postganglionic

neuron: releases NE

receptor: receives NE

Front 22

Cholinergic Neuron

Back 22

preganglionic

releases ACh

Front 23

Nicotinic

Back 23

preganglionic

receives ACh

excitation

Front 24

Muscarinic

Back 24

Postganglionic

receives ACh

excite or inhibit

Front 25

all preganglionic neurons....

Back 25

are cholinergic...release ACh to NICOTINIC receptors (cause excitation)

Front 26

all postganglionic neurons...

Back 26

are adrenergic...release NE to ADRENERGIC receptors (SNS) or ACh to MUSCARINIC receptors (PNS)

Front 27

Sympathetic Responses

Back 27

f or f= prepares for acute stress or phys activity

response caused by phys or emotional stress (E situations: emergency, embarrassment, excitement, exercise)

pupils dilate, airways dilate, respiratory rate inc, inc HR, inc force of contraction & BP, blood flow to skeletal & cardiac muscle; inc blood glucose levels

inc BP and mental activity

dec bloodflow to nonessential areas

some organs have ONLY sympathetic innervation (sweat glands, adrenal medulla, arrector pili, many bvs)
--controlled by reg of the "tone" of the sympathetic sys

NE- major neurotransmitter

Front 28

Parasympathetic Responses

Back 28

rest and digest

conserve& restore energy

dec'd HR, diam of airways and coronary vessels

normally dominate over sympathetic impulses

SLUDD responses: salavation, lacrimation, urination, digestion & defecation

ACh major neurotransmitter

Front 29

Enteric NS

Back 29

supports digestion & metabolism

innervates the viscera (GI tract, pancreas, gall bladder)

butterflies in stomach

involuntary body processes

2 neurons in pathway

Front 30

Reflex

Back 30

Fast, predictable, automatic response to changes in env to help maintain homeostasis

simplest type of pathway

lvl of brain involvement varies

how ANS operates

some inborn, some learned

Front 31

Gray matter

Back 31

dendrites & cell body

integration center for reflexes

Front 32

White matter

Back 32

axons

highways for nerve impulse propagation

Front 33

Components of Reflex Arcs

Back 33

1. Sensory Receptor
- produces a generator or receptor potential
2. Sensory Neuron
- axon conducts impulses from receptor to integrating cntr
3. Integrating Center
4. Motor Neuron
- axon conducts impulses from integrating center to effector
5. Effector
-muscle or gland that responds to motor nerve impulses

Front 34

muscle spindle

Back 34

purpose- sense muscle LENGTH

neurons "report" stretch to CNS

helps CNS to give info ab bodys position

muscles contract (reflex) to resist further stretching

Front 35

patellar stretch reflex

Back 35

ex of how muscle spindle works

1. stretching stimulates sensory receptor (muscle spindle)
2. sensory neuron excitd
3. integrating center, sensory neuron activates motor neuron
4. motor neuron excited
5. effector- contraction relieves stretching of the same muscle

Front 36

golgi tendon organs (GTO)

Back 36

Sense changes in muscle TENSION

Located close to tendon & muscle attachment

Inhibit agonist muscle contraction & excite antagonist muscles to prevent injury

i.e. quad vs. hamstring (stop contracting of quad, strt contracting of hamstring)

Front 37

4 pts of the brain

Back 37

1. brain stem
2. cerebellum
3. diencephalon
4. cerebrum

Front 38

midbrain

Back 38

relays motor output from cerebral cortex to pons; sends sensory input from spinal cord to thalamus

Front 39

pons

Back 39

relays impulses from one side of the cerebellum to the other, relays impulses frm medulla to midbrain; also regulates breathing

Front 40

medulla oblongata

Back 40

relays sensory input and motor output between brain and spinal cord; consciousness & arousal; regulates heartbeats, blood vessel diameter & breathing

Front 41

brain stem

Back 41

composed of midbran, pons, and medulla oblongata

regulates basic vital signs/primitive functions

acts as a relay station between the spinal cord & brain

Front 42

cerebellum

Back 42

compares intended to actual movements

coordinator (strings together series of movements into 1 complex motor movement)

regulates posture & balance

Front 43

thalamus

Back 43

relays sensory input to cerebral cortex

helps to plan and control movements

perceives touch, pressure, pain, temperature

Front 44

hypothalamus

Back 44

controls & integrates ANS & pituitary gland

emotion & behavior; body temp; eating & drinking; sleep, ADH &oxytocin

Front 45

epithalamus

Back 45

pineal gland which secretes melatonin (regulate sleep-wake cycle)

Front 46

cerebrum

Back 46

sensory areas: perceive sensory info

motor areas: plan & initiate muscular movements

association areas: memory, personality, intelligence

basal ganglia: coordinate gross movements & muscle tone (works w/ cerebellum)

limbic system: emotion, survival [instinctual]
-amygdala- fear

Front 47

basal ganglia

Back 47

parts: globus pallidus, putamen, caudate nucleus

part of the cerebrum

associated w/ sustained and repetitive movements

Front 48

putamen & caudate nucleus

Back 48

parts of the basal ganglia that receive sensory & motor input from the cerebral cortex

Front 49

globus pallidus

Back 49

pt of the basal ganglia; gives output, sends feedback signals to motor cortex via thalamus

Front 50

Summary of Integration Centers

Back 50

SC: simple motor reflexes

Lower Brain Stem: more complex subconscious motor reactions such as postural control

Cerebellum: subconscious control of movement such as those needed to coordinate multiple movements

Thalamus: conscious distinction among sensations such as feeling hot, cold, tired

Cerebral cortex: perceive sensory info; conscious movements

Front 51

Primary Motor Cortex

Back 51

pt of the ceerbrum

plans & initiates voluntary movement; starts movements

Front 52

Cerebellum

Back 52

necessary to produce movement

intentions vs. actual movements

posture & balance, corrections, fast & complex movements

Front 53

engrams

Back 53

memorized motor patterns stored in the brain

make program in brain i.e. for how to ride a bike

actually changes the structure of the brain

Front 54

learning

Back 54

ability to acquire new information or skills via instruction or experience

Front 55

memory

Back 55

info acquired via learning is stored & retrieved

must produce structural & functional changes

limbic system, hippocampus, amygdala, diencephalon, primary somatosensory & primary motor areas ==> all help to acquire memory

Front 56

types of memory

Back 56

immediate: few seconds (where, what)

short-term: seconds to mins (phone #)

long-term: days to yrs (retrieve anytime)

Motor skill memories: basal ganglia, cerebellum, cerebral cortex [[call upon these to do a motor skill related to memory]]