L12 - PNS II Flashcards
2 divisions of the PNS and where they receive from/carry info to
Afferent: from sensors to CNS
Efferent: From CNS to effector organs, muscles, glands, etc.
3 components of the efferent nervous system
- Autonomic NS
- Somatic NS
- Enteric NS
Sweat glands are only innervated by _____ nerves
Sympathetic
The autonomic nervous system innervates:
smooth muscle, cardiac muscle, glands, and non-motor organs.
ANS is subdivided into _____ and _____ nervous systems
ANS is subdivided into SYMPATHETIC and PARASYMPATHETIC nervous systems
Digestive activities are controlled by the ____ nervous system, the _____ nervous system, and by _____
Digestive activities are controlled by the AUTONOMIC nervous system, the ENTERIC nervous system, and by HORMONES.
What types of organs does the enteric NS supply?
digestive organs only
3 classes of neurons:
efferent, afferent, and interneurons
Afferent neurons have a sensory receptor at their ____ ending
Afferent neurons have a sensory receptor at their PERIPHERAL ending
What does the cell body of an afferent neuron lack?
Dendrites and presynaptic inputs
What does the sympathetic nervous system promote responses to prepare vertebrates for?
strenuous physical activity (ex: physical threat)
ANS regulation of many targets shows three characteristics:
- dual innervation
- continuous antagonistic actions of SNS and PNS
- Smooth muscle shows a basal tone (i.e., lowest possible level) that is modified by ANS input.
Where is the cell body of an afferent neuron located?
adjacent to the spinal cord in a ganglion (central axon passes into the dorsal root of the spinal cord)
The peripheral axon of an afferent neuron extends from the ____ to the ____ ____ and is (long/short?)
The peripheral axon of an afferent neuron extends from the RECEPTOR to the CELL BODY and is LONG.
The central axon of an afferent neuron extends from the ____ ____ into the ____ and is (long/short?)
The central axon of an afferent neuron extends from the CELL BODY into the SPINAL CORD and is SHORT.
Which type of neuron exists entirely within the CNS?
interneuron
Efferent neuron cell bodies originate in the ___
CNS
about 99% of mammalian neurons are ____
interneurons
more complex actions require a greater number of ________
interneurons
Effect of sympathetic/parasympathetic stimulation on:
heart
SNS: increased HR and force of contraction of whole heart (B1)
PNS: Decreased HR and force of contraction of atria only.
Effect of sympathetic/parasympathetic stimulation on:
blood vessels
SNS:constriction (a1)
PNS: dilation of the penis and clitoris only
Effect of sympathetic/parasympathetic stimulation on:
lungs
SNS: dilation of bronchioles (B2). Inhibition of mucus secretion (a)
PNS: constriction of bronchioles. Stimulation of mucus secretion.
Effect of sympathetic/parasympathetic stimulation on:
digestive tract
SNS: Decreased mobility (a2, B2). Contraction of sphincters to prevent forward movement of contents (a1). Inhibition of digestive secretions (a2).
PNS: increased motility. Relaxation of sphincters. Stimulation of digestive secretions.
Effect of sympathetic/parasympathetic stimulation on:
gallbladder
SNS: relaxation
PNS: contraction (emptying)
Effect of sympathetic/parasympathetic stimulation on:
urinary bladder
SNS; relaxation (B2)
PNS: Contraction (emptying)
Effect of sympathetic/parasympathetic stimulation on:
eye
SNS: Dilation of pupil (contraction of radial muscle) (a1). Adjustment for far vision (B2)
PNS: Constriction of pupil (contraction of circular muscle). Adjustment for near vision.
Effect of sympathetic/parasympathetic stimulation on:
liver (glycogen stores)
SNS: glycogenolysis (glc release) (B2)
PNS: None
Effect of sympathetic/parasympathetic stimulation on: adipose cells (fat stores)
SNS: Lipolysis (FA release) (B2)
PNS: None
Effect of sympathetic/parasympathetic stimulation on:
exocrine pancreas
SNS; inhibition of pancreatic exocrine secretion (a2)
PNS: Stimulation of pancreatic exocrine secretion (important for digestion)
Effect of sympathetic/parasympathetic stimulation on:
sweat glands
SNS: Stimulation of secretion by MOST sweat glands (a1)
PNS: stimulation of secretion by SOME sweat glands
Effect of sympathetic/parasympathetic stimulation on:
salivary glands
SNS: stimulation of small volume of thick saliva rich in mucus (a1)
PNS: stimulation of large volume of watery saliva rich in enzymes
Effect of sympathetic/parasympathetic stimulation on:
adrenal medula
SNS: Cholinergic stimulation of epinephrine and norepinephrine secretion
PNS: none
Effect of sympathetic/parasympathetic stimulation on:
Endocrine pancreas
SNS: inhibition of insulin secretion, stimulation of glucagon secretion (a2)
PNS: stimulation of insulin and glucagon secretion
Effect of sympathetic/parasympathetic stimulation on:
genitals
SNS: ejaculation and orgasmic contractions
PNS: erection of penis and clitoris
Effect of sympathetic/parasympathetic stimulation on:
brain activity
SNS: increased alertness
PNS: none
increased HR, opening of respiratory airways, glyc and fat breakdown, and dilation of blood vessels are all the _____ nervous system’s way of increasing ____ and _______ blood to skeletal muscles in anticipation of ____ ____
increased HR, opening of respiratory airways, glyc and fat breakdown, and dilation of blood vessels are all the SYMPATHETIC nervous system’s way of increasing OXYGEN and NUTRIENT-ENRICHED blood to skeletal muscles in anticipation of STRENUOUS ACTIVITY.
Innervated blood vessels are mostly under ____ control
Innervated blood vessels are mostly under SYMPATHETIC control (except penis and clit)
the autonomic nerve pathway is a ___-neuron chain
two-neuron chain
SNS neurons originate in the _______ regions of the spinal cord
SNS neurons originate in the THORACOLUMBAR regions of the spinal cord
PNS neurons originate in the __ and ___ region of the spinal cord
PNS neurons originate in the BRAIN and SACRAL region of the spinal cord
SNS has ___ ____ preganglionic fibers and ___ ___ postgangionic fibers
SNS has SHORT CHOLINERGIC preganglionic fibers and LONG ADRENERGIC postganglionic fibers
PNS has ____ ____ preganglionic fibers and ___ ___ postganglionic fibers.
PNS has LONG CHOLINERGIC preganglionic fibers and SHORT CHOLINERGIC postganglionic fibers
the adrenal medulla releases E and NE into the ___
blood
Which nerve accounts for 90% of all parasympathetic fibers in the body and serves almost all organs in the thoracic and abdominal cavities?
Vagus nerve
3 options for preganglionix axon once it reaches a sympathetic nerve trunk ganglion
- synapse at the same level
- synapse at a higher or lower level
- synapse in a distant collateral ganglion anterior to the vertebral column
site of origin of PS vs S fibers
PS: fibers are craniosacral
S: fibers are thoracolumbar
location of ganglia in PS vs S fibers
PS: ganglia are located in or near visceral effector organs
S: ganglia are close to spinal cord
Effects of neurotransmitters depend on the ____
receptor
which receptor type is found on the postganglionic cell bodies in all autonomic ganglia?
cholinergic nicotinic receptors
Cholinergic nicotinic receptors respond to which NT?
ACh
What occurs when ACh binds with a cholinergic nicotinic receptor?
binding of ACh to receptor causes nonspecific cation channels to open in the postganglionic cell. This permits passage of both Na+ and K+, causing the CELL TO DEPOLARIZE (since more Na+ enters the cell than K+ leaves)
Which receptor type is found on effector cell membrane innervated by parasympathetic fibers?
Cholinergic muscarinic receptors
How do cholinergic muscarinc receptors bring about a response?
By binding to ASCh released by PS postganglionic fibers. This receptor is linked to a G protein which activates a 2nd messenger system.
4 types of adrenergic receptors
a1, a2, B1, B2
B2 receptors primarily bind with _____
epinephrine
B1 receptors bind with ____ and ____
E and NE
T/F ALL adrenergic receptors are coupled to G proteins
TRUE
activation of B1 and B2 receptors brings about target cecll response by means of the ______________ system.
activation of B1 and B2 receptors brings about target cecll response by means of the CYCLIC AMP 2ND MESSENGER system.
Stimulation of a1 receptors elicits a response via the _________ system
Stimulation of a1 receptors elicits a response via the IP3/Ca2+ 2ND MESSENGER system
a2 stimulation responds via blocking ________ production in the target cell. This inhibits the response in the effector organ.
a2 stimulation responds via blocking CYCLIC AMP production in the target cell. This inhibits the response in the effector organ.
Atropine ___ the effect of ACh at ____ receptors but does not effect ______ receptors
Atropine BLOCKS the effect of ACh at MUSCARINIC receptors but does not effect NICOTINIC receptors
subtype “1” of adrenergic receptors is usually ____ and subtype “2” is usually ____
subtype “1” of adrenergic receptors is usually EXCITATORY and subtype “2” is usually INHIBITORY
Which adrenergic receptor is found primarily in the heart?
B1
Does atropine block sympathetic or parasympathetic NS?
Atropine blocks parasympathetic NS
SNS has two types of ganglia:
sympathetic chain ganglia and collateral ganglia. Located near spinal cord.
PNS has one type of ganglion:
terminal ganglia. Located near walls of target organs.
Which is more branched? S division or PS division?
sympathetic
What is the region which is most directly responsible for autonomic output? Controls cardiovascular, respiratory, digestion?
the medulla within the brainstem.
NT affinities in alpha and beta receptors
alpha receptors have a greater affinity for NE than E.
Beta 1 receptors bind equally to both.
Beta 2 receptors bind primarily to E.
