Nervous system - Lectures 8-9 (ANS) Flashcards
Effector organs of somatic motor system (1) vs autonomic nervous system (4)?
- how many effector neurons per system ish
- voluntary or involuntary
- somatic –> skeletal muscles! –> 1 neuron –> voluntary
- autonomic –> smooth muscle, cardiac muscle, exocrine/endocrine glands, adipose tissue –> 2 neurons –> MOSTLY involuntary –> can be voluntary with traning (ie peeing, pooping, meditation)
sympathetic = _____ or ______
parasympathetic = ______ and ______
- SNS: fight or flight
- PNS: rest and digest
- Autonomic reflexes work with (2) systems to maintain ___________
- control center of autonomic reflexes –> 3
- what does autonomic reflexes do? (2)
- work with endocrine and behavioral system to maintain homeostasis
- hypothalamus + brain stem (pons, medulla) + spinal reflex (doesn’t need integration in brain)
- receives (?) sensory info from somatosensory and visceral receptors + motor output leads to autonomic, endocrine and behavioral responses
- behavioral responses may be integrated in _____ _______ into _______ behaviors and to control ___________
- sensory info that are integrated in ______ and ______ system, create ________ that influence autonomic output
- brain centers into motivated behaviours to control movement
- integrated in cortex and limbic system, create emotions
autonomic center has control over 2 major organs
- what does each of these organs control? 5 each
HYPOTHALAMUS:
- temp control
- water balance
- eating behavior
- sleep
- sex drive
BRAIN STEM:
- urinary bladder control
- blood pressure control
- respiratory system + secondary respiratory system
- heart beat
- swallowing/digesting
most internal organs are under __________ control –> one branch is excitatory, the other branch is inhibitory
- 2 exceptions
- what determined response in target tissue?
- antagonistic
- sweat glands (epithelial cells) and smooth muscles in most blood vessels/arteries –> ONLY sympathetic innervation + tonic control
- neurotransmitter receptor!
what is dual innervation?
- what is tone?
DUAL INNERVATION:
- target organ can get input from both sympathetic and parasympathetic –> technically both systems have opposite functions (ie accelerate or brake)
TONE:
- both function at same time but 1 is dominant (ie heart beat: sympathetic dominant when you run vs when you sleep, parasymp. is dominant –> shows tonic control (?))
preganglionic vs postganglionic neuron
- combientième neuron in chain + cell body located where?
- projects from where to where?
- synapses to what?
PREGANGLIONIC:
- first neuron in chain with cell body located in CNS
- projects from CNS to an autonomic ganglion outside CNS
- synapses with postganglionic neuron
POSTGANGLIONIC:
- 2nd neuron in chain with cell body located in autonomic ganglion
- projects from autonomic ganglion to target tissue
- synapses with target cell
ganglion = what?
- also contain what?
- act as what?
- ganglion = cluster of neuronal cell bodies outside CNS
- also contain neurons completely within
- act as mini integration centers
autonomic pathways consists of # neurons that synapse where?
2 neurons that synapses in an autonomic ganglion
synapse vs neural effector junction vs neural muscular junction
- synapse: connection between 2 neurons
- neural effector junction: between 1 neuron and effector cell that is not skeletal muscle
- neural muscular junction: btw 1 somatic motor neuron and 1 skeletal muscle fiber
sympathetic pathway:
- branches out from which regions of spinal cord?
- sympathetic ganglia in 2 ganglion chains along either side of what?
- thoracic and lumbar regions of spinal cord –> T1 to T12 + L1-L2
- either side of vertebral column
3 scenarios for sympathetic post-ganglionic neurons?
- axon synapses with postganglionic neurons in first ganglion it reaches (short first neuron + long 2nd neuron)
- axon may continue, without synapsing, through sympathetic trunk ganglion to end at a prevertebral/collateral ganglion (halfway btw spinal cord and effector organ) and synapse with postganglionic neurons there
- axon may passe through sympathetic trunk ganglion and collateral ganglion and then to the adrenal medulla (no synpases –> adrenal medulla can produce hormones (endocrine system)
what is the most dominant pathway for SNS?
chain ganglions! short first neuron –> synapse in sympathetic ganglion chain –> long postganglionic neuron
parasympathic system:
- branches out from where
- which nerve accounts for 75% of PSNS?
- parasympathetic ganglia located on or near what?
- brain stem + leave brain in cranial nerves (4 craniosacral nerves) + 3 sacrospinal nerves (S2, S3, S4)
- vagus nerve!
- near target organs
most dominant pathway for parasympathetic system?
- quite long 1st neuron –> gets really close or into organ before interacting with terminal ganglion –> synpases with short postganglionic neuron
vagus nerve:
- contains about ___% of all para or sympathetic fibers?
- sensory info from what to what + output from what to what?
- 75% of parasympathetic fibers
- internal organs to brain + output form brain to organs
what are the 2 exceptions where parasympathetic and sympathetic don’t work oppositely?
SALIVA:
- watery saliva = increased by PSNS
- mucusy salive (more dry) = increase by SNS)
BLOOD VESSELS:
- SNS induces ejaculation + PSNS induces erection
- SNS stimulates uterus contraction + PSNS regulates engorgement and secretions
SNS or PSNS:
- relaxes airways
- constricts airways
- inhibits digestion
- slows heart rate
- increases bile secretion
- relaxes bladder
- release of urine
- increases motility and secretion in intestines
- pupil dilates
- increases renin secretion
- releases enzymes and insulin from pancreas
- relaxes airways SNS
- constricts airways PSNS
- inhibits digestion SNS
- slows heart rate PSNS
- increases bile secretion PSNS
- relaxes bladder SNS
- release of urine PSNS
- increases motility and secretion in intestines PSNS
- pupil dilates SNS
- increases renin secretion SNS
- releases enzymes and insulin from pancreas PSNS
what neurotransmitter do sympathetic and parasympathetic PREganglionic neurons release?
- onto what receptor? 2 types
- both release acetylcholine!
- nicotinic cholinergie receptors (nAChR) on the postganglionic cells –> Nn (on neuron) or Nm (on muscle)
what neurotransmitter do sympathetic and parasympathetic POSTganglionic neurons release?
- onto what receptor?
SYMPATHETIC:
- norepinephrine –> adrenergic receptors on target cells (alpha (1 or 2) or beta (1, 2 or 3))
PARASYMPATHETIC:
- secrete acetylcholine onto muscarinic cholinergic receptors (mAChR) –> M1 to M5 (we focus on M2 and M3)
exceptions!
- sympathetic cholinergic neurons (postganglionic) on sweat glands secrete what neurotransmitter? (instead of what normally?)
- which neurons use other types of neurotransmitters?
- acetylcholine! instead of norepinephrine
- nonadrenergic and noncholinergic neurons
which nervous system:
- nicotinic cholinergic receptors
- muscarinic cholinergic receptors
- a adrenergic receptor
- b adrenergic receptor
- Nn or Nm –> both SNS and PSNS
- M1 to M5 –> PSNS
- a1, a2, b1, b2, b3 –> SNS
autonomic pathways control ______ and _____ muscle and _______
- what at the end of the postganglionic neuron can release autonomic neurotransmitters over surface of target cells? –> goal?
- smooth and cardiac muscle and glands
- varicosities! goal = increase effect of neurotransmitters
____ node controls heartbeat
- mostly 2 receptors –> which one are controlled by which neurotransmitter from which autonomic division? –> result in heart rate
SA node
- increase b1 –> NE from SNS –> increase heartrate (contraction)
- decrease M2 –> Ach from PSNS –> decrease heart rate
bronchial smooth muscle:
- which 2 receptors-neurotransmitter pair induces relaxation vs contraction?
VS smooth muscle blood vessel:
- which receptor is increased?
- decrease b2 –> NE from SNS –> relaxation for running
- increase M3 –> Ach from PSNS –> contraction (less air gets in/out)
- smooth muscle: increase alpha (SNS) to increase blood pressure
- nicotinic receptors exist on all ________ _______
- muscarinic receptors exist on all _________ _____ ________
- which (3) actions ish are integrated at the spinal cord level?
- vs centers for cardiovascular, respiratory and digestive activities are located in the ________
- autonomic ganglia
- effector cell membranes
- urination, defecation, erection
- medulla
roles + mostly found where?:
- a1: contraction of (2)
- a2: (5)
a1: contraction of vascular and genitourinary smooth muscle
- mostly found in smooth muscle for blood vessels + most sympathetic target tissues
a2:
- contraction of vascular smooth muscle
- decreased insulin secretion
- decreased cAMP
- aggregation of platelets
- pre-synaptic inhibition of NE
- found in gastrointestinal tract and pancreas
roles + found in?
- b1: effects on ?
- b2: relaxes (4) + stimulates (2) in liver
- b3: ?
b1: positive inotropic and chronotopic effects on heart –> increase heart contraction
- found in heart muscle, kidney
b2:
- relaxes vascular, bronchial, gastrointestinal and genitourinary smooth muscle
- stimulaes glyconeolysis and gluconeogenesis in liver
- found in certain blood vessels and smooth muscle of some organs + bronchile!
b3: lipolysis in adipose tissue
- found in adipose tissue
what medication will block which receptors to decrease high blood pressure?
- beta block!
- block b receptors –> effect from SNS will decrease = more PSNS –> decrease heart rate
REVIEW OF SYNAPSES:
- 2 things can happen when neurotransmitters bind to receptors?
- first thing –> 3 different molecules –> 2 different results
- 2nd thing –> what happens?
- can open channels!
- Na+ OR Ca2+ channels –> get into cells = depolarization = graded potential –> Excitatory post synaptic potentials (EPSP) –> needs to go through summation to get AP
- Cl- channels –> get into cells = hyperpolarization –> IPSP - can bind to G protein coupled receptors –> induce 2° messengers –> enzyme changes –> may or may not induce AP
GPCR, ion channels or both?
- alpha and beta adrenergic receptors
- nicotinic and muscarinic receptors
- a and b –> GPCR
- N and M –> GPCR and some ion channels –> can change membrane potential
3 components of the neuromuscular junction?
- axon terminal
- synaptic cleft
- motor end-plate
what is EPP? how is it induced? (4)
- end-plate potential!
- Nm receptors on motor end-plate open sodium channels –> changes membrane potential –> induces EPP –> always big enough to reach threshold = AP!
Action potential arrives at varicosity –> (+4 steps)
- how to “remove” neurotransmitter? (3)
- AP at varicosity
- depolarization opens voltage gated Ca2+ channels
- Ca2+ entry triggers exocytosis of synaptic vesicles –> release NE
- NE binds to adrenergic receptor on target
- receptor activation ceases when NE diffuses away from synape
- NE can be taken back into synaptic vesicles for re-release
- NE is metablized by monoamine oxidase (MAO) which breaks down NE
reacts more to NE or E? or both?
- alpha receptors
- b1
- b2
- b3
- alpha receptors: strongly to NE (and weakly to E)
- b1 (heart): equally to NE and E
- b2 (bronchile): more sensitive to E than NE
- b3: more sensitive to NE than E
neurotransmitters in SYMPATHETIC VS PARASYMPATHETIC
- synthesized from?
- inactivation enzyme?
- varicosity membrane transporters for? (when reuptaken into presynaptic neuron?
SYMPATHETIC:
- NE synthesized from tyrosine
- monoamine oxidase (MAO) in mitochondria of varicosity
- NE
PARASYMPATHETIC:
- Ach synthesized from acetyl-CoA + choline
- Acetylcholinesterase (AChE) in synaptic cleft
- choline (only choline is left after AChE activity)
effects of a1, a2, b1, b2 and b3 on second messengers?
a1 –> increases IP3 and intracellular Ca2+ + increases PKC
a2 –> decreases cAMP
b1, b2 and b3 –> increases cAMP
where are each cholinergic receptors found in? + effect on second messenger?
Nn:
- postganglionic autonomic neurons
- opens non specific monovalent cation channels
Nm:
- skeletal muscle
- opens non specific monovalent cation channels
M1, M2, M3, M4 and M5: nervous system and parasympathetic target tissues
M1, M3 and M5 –> increases IP3 and intracellular Ca2+ + increases PKC (induces bronchile contraction)
VS M2 and M4 –> decreases cAMP, opens K+ channels (more hyperpolarization –> decrease heart contraction)
why is smoking a cardiac risk factor? (2)
- blood vessels are primarily influenced by the SNS –> nicotine activation of autonomic ganglia –>
- NE released and binds with a1 –> contraction of blood vessel = increase blood pressure - cardiac muscle tissues only modulated by autonomic inputs –> conflicting info from both SNS and PSNS postganglionic fibers will cause arrhythmias
- NE released in SNS binds with b1 –> increase heart rate
- Ach released in PSNS binds with M2 –> decreases HR
heart receives input from SNS and PSNS. what is the actual difference btw sympathetic and parasympathetic divisions at synapse btw neurons and cardiac muscle?
- SNS –> NE –> adrenergic receptors
- PSNS –> Ach –> muscarinic receptors
- which receptors are bound is the signal that determines how the heart responds
adrenal medulla is a ____________ tissue. is also a modified _________ ____________
- innervated by sympathethic or parasympathethic preganglionic fibers?
- postganglionic neurons (_________ cells) lack ______ –> secrete (which neurotransmitter) into the _______
- neuroendocrine tissue + modified sympathetic ganglion
- sympathethic preganglionic fibers
- chromaffin cells lack axons –> secrete mostly epinephrine (75%) into the blood
where is the adrenal gland?
above the kidney
somatic motor pathway consists of how many neurons?
- originates in _____ –> in (2)
- always inhibitory or excitatory?
- terminal branches close/far to target and each terminal innervates what?
- 1 neuron!
- CNS: brain and ventral horn of spinal cord
- always excitatory –> EPP!
- close to target –> each terminal innervates a single skeletal muscle fiber
which enzyme is on end plate/in synaptic cleft of a neuromuscular junction?
achetylcholinesterase (AChE)
M subtype nicotinic receptors :
- ________ -gated channels with (#) bindings sites for ________
- always excitatory/inhibitory –> creating what?
- chemically gated with 2 binding sites for ACh
- excitatory! creating muscle contraction –> 1 AP in neuron induces 1 AP on target muscle
what is the motor end-plate?
region of muscle membrane that contains high concentrations of ACh receptors
somatic motor neurons:
1. AP arrives at axon terminal –> causing what?
2.
3.
4.
5. depolarization of post-ganglionic cell
6. what happens to the neurotransmitter?
- AP arrives at axon terminal –> causing voltage-gated Ca2+ channels to open
- Calcium entry causes synaptic vesicles to fuse with presynaptic membrane –> releases ACh into synaptic cleft
- Nicotinic cholinergic receptors (Nm) binds 2 ACh molecules, opening non-specific monovalent cation channels
- Open channel allows Na+ and K+ to pass
- Net Na+ influx depolarizes muscle fiber
- ACh is metabolized by acetylcholinesterase
somatic motor pathways:
signals come from:
- upper motor neurons via _________ tracts
- _______ ________ –> helps with muscle tone
- ___________ –> coordination
- sensory neurons or interneurons via __________
- corticospinal tracts
- basal ganglia helps with muscle tone
- cerebellum –> coordination
- via reflexes!
impulses from somatic motor pathways activate lower motor neurons (cell bodies in what?)
- axons –> ______ _____ –> ________ nerve –> ______ –> voluntary movement
- lower motor neurons
*cell bodies in anterior gray of spinal cord - axons –> ventral root –> spinal nerve –> muscle –> voluntary movement
primary motor cortex:
- 2 tracts come out of it?
- where do each go to? control what part of body?
- the second one has 2 different tracts: explain
- cortico bulbar tract –> goest to brain stem (doesn’t go to spinal cord) –> where they interact with 2° neuron –> controls neck, face, head, skeletal muscles
- corticospinal tract –> goes to spinal cord –> controls everything below brain stem –> passes through pyramid where it separates into:
1. right anterior corticospinal tract –> small amount controlled –> go on same side until spinal cord –> crossover at spinal cord + interact with 2° neuron
2. left lateral corticospinal tract –> major one! most muscles controlled by it –> crossover at medulla –> interact with 2° neuron –> to skeletal muscle
