Chapter 5: Peripheral Nervous System Flashcards
the PNS:
contain nerve fivers that carry information between the CNS and other parts of the body.
PNS is diveded into the ____ and ____ division
1) afferent: forward carrying signals towards the CNS.
2) efferent: transmits instructions from CNS to effector organs. Heavily utilizes Ach and Ne
3 components of the efferent division
1) autonomic NS: innervates smooth muscle, cardiac, glands and involuntary organs.
2) somatic NS: consists of fibers of motor neurons that supply skeletal muscles, controls reflects and non reflex skeletal muscle actions.
3) enteric NS: extensive nerve network in the wall of the digestive tract that works with the Autonomic SN and hormones to control digestive activites.
the ___ neurons are mainly in the PNS. Their cell bodies are located near the dorsal root ganglion of the spinal cord, and they contain a sensory receptor at the peripheral end that generates an AP in response to a stimulus
afferent neurons. they convey info from outside (collected by sensory receptors), and transmits it to the CNS.
For Efferent (and thus autonomic neruons) have their cell bodies originating near the ___ ___ of the CNS, and their axon terminals leave to innervate ___ or ___
For Efferent (and thus autonomic neruons and somatic and enteric neurons) have their cell bodies originating near the VENTRAL ROOT HORN of the CNS, and their axon terminals leave to innervate MUSCLES or GLANDS
the autonomic nervous system is part of the ____ division of the PNS, and is further divided into the ___ and ___ systems.
the autonomic nervous system is part of the EFFERENT division of the PNS, and is further divided into the SYMPATHETIC and PARASYMPATHETIC systems.
describe dual innervation
any gland or muscle that is contolled by the autonomic nervous system is undercontrol of the sympathetic AND Parasympathetic nervous system at the same time.
the dual innervation PS and S systems act as an ____ ____ feedback system
antagonistic negative feedback system, they often exert generally the opposite effects.
what is parasymp or symp dominance?
usually, there is both sympathetic and para symp activity occuring at the same time on a gland/effector. But when one system takes over, that is called dominance
describe the general autonomic nerve pathway. What is the exception to this?
each autonomic nerve pathway consists of a 2-neuron chain. The PREGANG fiber (an efferent fiber) originates in the CNS, and synapses with the POST GANGLIONIC fiber in an AUTONOMIC GANGLIA OUTSIDE of the CNS.
All parts of the autonomic nervous system has a 2-neuron chain except the adrenal medulla, in which the preganglion neuron originating in the CNS synapses directly onto the medulla.
the post ganglionic fiber of the Autonomic nervous system pathway has axonal _____, which:
axonal varicosities: bulges in the axon that has the ability to release neurotransmitters and neuromodulators to a LARGE area on an effector
the hypothalamic pituitary adrenal axis in part of the ____ nervous system of the autonomic NS
sympathetic nervous system
the HPA axis is stimulated by ____, causing the hypothalamus to release ____, which moves to the pituitary gland to trigger the release of _____. _____ stimulates the adrenal galnd, promoting ___ and ___ release.
the HPA axis is stimulated by STRESS, causing the hypothalamus to release CTH, which moves to the pituitary gland to trigger the release of ACTH. ACTH stimulates the adrenal galnd, promoting CORTISOL and CATECHOLAMINE release.
which catecholamines are typically released by the HPA axis?
primarily epinephrine and NE. ( mostly epinephrine)
In terms of the HPA axis, what is the secondary response? primary response? tertiary response?
pirmary response: release of cortisol and catecholamines in response to the hypothalamus detecting stress
secondary response: the effects of cortisol and epinephrine (effects metabolic nutrients, the ion concentration gradients etc.)
tertiary response: change in the whole organism (ex/ growth, disease resistance, behavior)
Allostasis
the process by which the body responds to stressors to regain homeostasis. NOT ENTANTOSTASIS, which is the maintenance of systems outside of homeostasis.
physiological definition of acute stress. is this normal?
acute stress is a stressor that elevates heart rate but later moves down to normal levels after the stress is gone. this is evolutionarily normal and it is expected that the body will maintain reactive homeostasis.
reactive homeostasis
the general range of homeostasis that allostasis tries to maintain.
T/F: the stress response is adaptive
true. but we have not yet evolved to manage chronic stress.
why is chronic stress so bad for us?
we have not yet evolved to manage chronic stress, resulting in frequent homeostatic overload because our allostatic mechanisms do not know what to do. this results in increase obesity, cvd and cancer.
the system that promotes general housekeeping activities such as digestion and urination
parasympathetic nervous system. works unconcsiously, many organs are at rest.
Affect of the PS and S on the heart
PS: decreased heart rate, decreased force of contraction
S: increased heart rate, increased force of contraction (Beta 1)
Affect of Ps and S on blood vessesl
PS: dilation
S: vasocontriction A1 (excitatory)
AFfect of PS and S on lungs
PS: CONTRICTION of bronchioles, stimulation of mucus secretion
S: Dilation of broncioles (B2), prevention of mucus secretion (alpha)
Affects of PS and S on digestive tract. What happens to the sphincters?
PS: stimulation of digestion, opening of the sphincters
S: inhibition of digestion (A2B2), closing of the sphincters (A1)
affect of Ps and S on gall bladder
PS: contraction (because the contents are needed for digestion)
S: Relaxation
Affects of Ps and S on bladder
PS: Constriction (makes you pee)
S: relaxation (no peeing)
Affects of Ps and S on eye. What happens to vision?
ps; Constriction of pupil, meant to see things close by
S: dilation of pupil (alpha 1), meant to see things far away.
Affects of PS and S on liver.
PS: NONE
S: glycogenolysis (B2)
Affects of PS and S on adipocytes
PS: none
S: lipolysis (B2)
Affects of PS and S on pancreas
PS: stimulation of pancreatic exocrine secretion (important for digestion
S: inhibition of pancreatic exocrine secretion (A2)
Affects of PS and S on sweat glands.
S; Stimulation of secretion by most sweat glands
Affects of Ps and S on salivary glands
PS: stimulation of large volume watery saliva rich in enzymes
S: stimulation of small volume thick saliva rich in mucus (alpha 1)
Affects of PS and S on adrenal medulla
PS: none
S: stimulation of epinephrine and NE secretion
Affects of PS and S endocrine pancreas
PS: Stimulation of insulin and glucagon secretion
S: Inhibition of insulin secretion (A2)
Affects of Ps and S on genitals
PS: causes erection
S: causes ejaculatoin an organismal contractions (A1)
Affects of Brain activity of PSa dn S
PS: none
S: increased alertness.
Basal tone
lowest possible level/most baseline activity that is modified by ANS input.
in terms of receptors, the subtype 1 is ____ and subtybe 2 is ____
in terms of receptors, the subtype 1 is EXCITATORY and subtype 2 is INHIBITORY
both alpha and beta receptors are ____ receptors and are coupled _____
both alpha and beta receptors are NE receptors and are coupled TO G PROTEINS
Even though Parasymp preganglia are primarily in the cranio-sacral regions on the spinal cord, how are organs that are in the thoraco-lumbar regions parasympathetically innervated?
by the vagus nerve. the post and pre gang neuron change synapse at the autonomic ganglia and the post gan PS fiber runs through the vagus nerve which serves all organs in the thoracic and abdominal cavities.
the sacral part of the para sympathetic division serves the ____ organs and which parts of the intestine?
the sacral part of the para sympathetic division serves the PELVIC organs and BOTTOM HALF of the LARGE INTESTINE
T/F: the cell bodies of a afferent neuron are directly inthe CNS
false. the cell body of an afferent neuron is just outside the CNS but then connects to the dorsal root horn.
all efferent neurons have their preganglionic cell bodies originating in the _____
VENTRAL ROOT
the preganglionic axon of the sympathetic nerve system synapses with the post ganglionic axon at the ___ ___ ____, there the post ganglionic axon runs later runs to the effector
sympathetic trunk ganglion
What happens when the pre ganglionic axon of a sympathetic nervous system does not synapse at the sympathetic trunk ganglion?
it usually runs further to reach a collateral ganglion, such as the CELIAC, MESENTERIC, or INTERIOR MESENTERIC ganglion, and then synpases in the collateral ganglion with the post ganglionic axon.
sympathetic nerve pathways to the head run through the ___
superior cervical ganglion
sympathetic nerve pathways to the middle body or thorax run through the ____
inferior cervical ganglion
the sympathetic nervous system pre ganglionic neurons are typically located in the ____ region of the CNS
thoracolumbar region
how do the PS and S neuron locations differ?
PS: fibers are craniosacral
S: fibers are thoracolumbar
How do the lengths of PS and S pre and post ganglionic fibers differ?
PS: Long preganglionic fiber, short post ganglionic fiber
S: short preganglionic axon, long post ganglionic axon.
how do the locations of the PS and S ganglia differ? (Ie/ where the pre and post ganglionic fibers synapse)
PS: ganglia are located near the visceral effector organs
S: ganglia ( the sympathetic trunk) is near the spinal cord
2 neurotransmitters of the ANS
1) acetyl choline
2) NE
in both the symp and para sym, what neurotransmitter is released by the preganlionic axon?
Ach
the does the symp post ganglionin axon release? Parasymp post ganglionic axon?
symp post ganglionin axon release NE
parasymp post ganglionin axon release Ach
which division of the autonomic nervous system would you find cholinergic nicotinic receptors?
you would find them in ALL AUTONOMIC GANGLIA, both symp and parasym. They respond to Ach released by the para and symp pre ganglionic fibers.
you would also find them on the MOTOR END PLATES or skeletal muscle (some in the somatic nervous system).
Cholinergic nicotinic receptors are ____ receptors.
ionotropic receptors. they allow Na+ influx
which division of the autonomic nervous system would you find cholinergic MUSCARINIC receptors?
you would only find them on the EFFECTOR ORGANS when ACh is released from the POST GANGLIONIC axon, thus, muscarinic receptors respond to Ach release from the PARASYMPATHETIC NS.
how many subtypes of muscarinic receptors are there?
5 subtypes, they are all metabotropic
all adrenergic receptors are:
coupled to G proteins
generally, you find beta 1 receptors in the
heart
generally, alpha 1 receptors are coupled to which G protein response?
IP2 and Ca2+ G protein responses.
what effect does alpha 2 have on g proteins?
blocks cAMP production, found in many glands.
two types of sympathetic ganglia
sympathetic chain trunk ganglia, and collateral ganglia.
which division of the autonomic nervous system is more branched?
sympathetic.
the ____ in the brain stem is the region most directly responsible for autonomic output (cardiovascular or digestion)
medulla
the ____ maintains stability of the internal environment and integrates emotional and behavioral states
hypthalamus.
the medulla can increase blood pressure by stimulating the sympathetic NS via the ____ nerve and by decrease the parasympathetic NS via the ____ nerve
the medulla can increase blood pressure by stimulating the sympathetic NS via the GREAT CARDIAC nerve and by decrease the parasympathetic NS via the VAGUS nerve
which effectors are exceptions to the autonomic dual innervation system?
1) blood vessels are primarily controlled by sympathetic NS except the penis and clitoris
2) sweat glans are primarily controlled by sympathetic nervous system
which gland is not under antagonistic control of the symp and para symp?
the salivary glands. both the symp and para symp induces saliva production, its just that the symp creates a more mucusy saliva
____ blocks th effects of ACH at muscarinic receptors, but does not affect nicotinic receptors.
atropine
contrast the autonomic and somatic nervous system in terms of number of neurons from origin in CNS to effector organ
autonomic: 2 neuron chain that synapses together in a ganglia
somatic: a single neuron branches from the cns strait to the muscle
contrast the autonomic and somatic nervous system in terms of the organs that are innervated
autonomic: cardiac, smooth, exocrinegland and endocrine gland
somatic; skeletal muscle
contrast the autonomic and somatic nervous system in terms of type of innervation
autonomic NS is dually innervated
somatic NS: the effector organs is only innervated by one type of neuron (motor neuron)
contrast the autonomic and somatic nervous system in terms of neuro transmitter used at the effector organs
autonomic uses NE for sympathetic and Ach for parasym
somatic only uses Ach
contrast the autonomic and somatic nervous system in terms of their stimulatory and inhibitory effects on the effector organs
autonomic: can be stimulatory (simp) or inhibitory (Parasym)
somatic: only stimulatory
contrast the autonomic and somatic nervous system in terms of the higher centers involved in control
autonomic: medulla, hypothalamus, PFC, spinal cord
somatic: spinal cord, motor cortex, basal nuclei, cerebellum (fine movement), brainstem.
contrast the autonomic and somatic nervous system in terms of types of control
autonomic: under reflex control, may be voluntarily controlled with biofeedback ( ex u can control swallowing to an extent)
somatic: some reflex control, also voluntary control
