1/10 Britton Autonomic and Nerve Physiology Flashcards
(144 cards)
1
Q
CNS
A
Brain and spinal cord
2
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PNS
A
Nerves that branch out from CNS al over the body
3
Q
Functional divisions of the nervous system
A
- Afferent
- Efferent
4
Q
_____ detects stimuli from the periphery and conduct APs to the CNS and are termed _____
A
Afferent; sensory neurons
5
Q
____ conducts APs from the CNS to effector organs, which are called _____
A
Efferent; motor neurons
6
Q
The ANS is responsible for the:
A
Unconscious activities of the body (ex. heart rate, blood pressure, GI tract motility, pupil dilation, saliva stimulation)
7
Q
Divisions of the ANS
A
- Sympathetic (fight or flight, mobilize body’s resources)
- Parasympathetic
8
Q
Many organs have ____ innervation
A
Dual
9
Q
Generally, SNS and PSNS have opposing ____ effects on target organs. The actions of the 2 divisions must be balanced in order to maintain _____
A
Antagonistic; homeostasis
10
Q
Arrangement of neurons in the ANS: both divisions of the ANS contain ____ and _____
A
Pre-ganglionic and post-ganglionic neurons
11
Q
Preganglionic neurons have cell bodies located within the
A
CNS
12
Q
Pre-ganglionic neurons of the SNS are located:
A
Within the spinal cord segments T1-L3
13
Q
SNS and PSNS have complementary effect in:
A
- Increasing salivary secretion
- sympathetic increases thickness and viscous
- PSNS increases watery secretion
14
Q
In the SNS, the preganglionic neuron is _____ than the post-ganglionic neuron
A
Shorter
15
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In the PSNS the preganglionic neuron is _____ than the post-ganglionic neuron
A
Longer
16
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Pre-ganglionic neurons of the PNS are located:
A
In the craniosacral regions of the CNS
17
Q
Pre-ganglionic neurons release NT’s onto:
A
Post-ganglionic neurons
18
Q
In the SNS, the pre-and post-ganglionic neurons synapse:
A
In the paravertebral ganglia
19
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In the PNS, the pre-and post-ganglionic neurons synapse:
A
Near or in the effector organs
20
Q
True or false: Adrenal medulla is stimulated both by the SNS and PSNS
A
False- only SNS
21
Q
After synapsing, post-ganglionic neurons then release NTs onto:
A
Effector organs
22
Q
Do parasympathetic nerves innervate the blood vessels?
A
No, only SNS
23
Q
Postganglionic neurons of the ANS store neurotransmitter within vesicles in ____ and release neurotransmitter over the surface of the target tissue
A
axon varicosities
24
Q
Autonomic nerves are divided into what 2 groups?
A
- Cholinergic
- Adrenergic
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Transmission of nerve impulses mediated by Ach
Cholinergic
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Transmission of nerve impulses mediated by NE and E
Adrenergic
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Noradrenaline is an alternative name for:
Norepinephrine (hence adrenergic)
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Cholinergic nerves can synapse with what types of receptors?
- Nicotinic (ligand-gated)
- Muscarinic (GPCR)
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Adrenergic nerves can synapse with what types of receptors?
- alpha-1
- alpha-2
- beta-1
- beta-2
- beta-3
(all adrenergic receptors which are GPCRs)
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Cholinergic receptors bind:
Ach
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Where are nicotinic receptors located?
- all post-ganglionic neurons of the ANS
- adrenal medulla
- neuromuscular junction of somatic nerves
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Nicotinic receptors are _____
Ligand gated ion channels
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True or false: nicotinic receptors are inhibitory usually
False - usually excitatory
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Muscarinic receptors are ____
G-protein coupled receptors
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Location of muscarinic receptors
- All effector glands and tissue innervated by the PNS (M1, M2, M3)
- Sweat glands innervated by the SNS
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Muscarinic receptors can be ____ or _____
Excitatory or inhibitory
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Why are muscarinic receptors both excitatory and inhibitory?
Depends on the associated G-protein and downstream signaling pathway
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Examples of parasymapthetic nervous system effectors
- smooth muscle
- gland cells
- nerve terminals
- cardiac muscle
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Examples of sympathetic nervous system effectors
- sweat glands
- smooth muscle
- gland cells
- nerve terminals
- cardiac muscle
- renal vasculature
- smooth muscle
- cardiac muscle
- vessels
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Somatic nerves synapse at _____. The NT associated is always ____
Skeletal muscle; Acetylcholine
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Almost all _____ are adrenergic neurons, meaning that they release ____. All adrenergic receptors are ____
Sympathetic post-ganglionic neurons; GPCR's
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Activation of adrenergic receptors on effector glands and tissues initiates:
Diverse G-protein intracellular signaling mechanisms
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Key locations of adrenergic receptors (alpha-1)
- blood vessels
- eye
- bladder
- prostate
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Key locations of adrenergic receptors (alpha-2)
- blood vessels
- GI tract smooth muscles
- CNS
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Key locations of adrenergic receptors (beta-1)
- heart
- kidney
- GI tract smooth muscle
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Key locations of adrenergic receptors (beta-2)
- lung
- liver
- blood vessels
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Key locations of adrenergic receptors (beta-3)
detrusor muscle of the bladder
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Subunits of G proteins
alpha, beta, gamma
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True or false: G proteins can have a different set of alpha, beta, gamma subunits
True
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Regarding G proteins, there are many different ___ subunits
alpha
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The G protein complex is often characterized by:
The type of alpha subunit present
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Examples of G protein alpha subunits: Ga(s)
Stimulated adenylyl cyclase
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Examples of G protein alpha subunits: Ga(i)
Inhibits adenylyl cyclase
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Examples of G protein alpha subunits: Ga(q)
Activated PLC-beta
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True or false: GPCRs are dimeric
False - heterotrimeric
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Somatic nervous system subdivision of the peripheral nervous system has 2 main functions, which are:
- sensory input
- movement control
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Motor functions of the somatic nervous system are responsible for:
- maintaining the body's posture and balance
- moving the trunk, head, links, tongue, eyes
- communicating through facial expressions and speech
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The somatic nervous system is a _____ - under conscious control
Voluntary motor system
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What are voluntary movements?
Movements that are consciously activated to achieve a specific goal, such as walking, typing chewing
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True or false: Although consciously activated, the details of most voluntary movements occur automatically
True
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Reflexes are ____ movements
Involuntary (occur without conscious thought)
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Reflexes are mediated through ____ and are responsible for ____ body movements
spinal cord and brainstem; some
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What is motor control?
Senses --> cognition --> action
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Through our ____, we perceive the world and our relationship to it
Senses
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What is cognition?
CNS processes sensory input to construct details of the environment
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Conscious actions require ________ to make actions adaptive and appropriate for a particular situation
Sensory input and cognitive processing
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In motor control, the final output is:
A set of commands to certain muscles in the body (ex. run from predator, seek shelter from rain, search for food when hungry, move lips and vocal cords to communicate)
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At the highest level, ____ controls voluntary movements
Motor cortex
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Motor cortex function
Processes information related to the planning and coordination of whole-body movements
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_____ make essential contributions to motor control
Basal ganglia and cerebellum
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At the most basic level, movement is controlled by _____, often with no help from the ____
Spinal cord; brain
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True or false: Distinct but highly interactive regions make similar contributions to motor control
False - UNIQUE contributions
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Voluntary movements result from stimulation of ____ neurons
Upper and lower motor neurons
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Upper motor neurons:
Cell bodies are in the _____
Axons form ____ that connect to _____
- Cerebral cortex
- Descending tracts; lower motor neurons
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Lower motor neurons: cell bodies are in:
- Cranial nerve nuclei
- Anterior horn of spinal cord
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Where do lower motor neurons send their axons out? What do they innervate?
Out of the brainstem and spinal cord; innervate skeletal muscles of the head and body (respectively)
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All commands for movement, whether voluntary or reflexive, are ultimately conveyed to ____ by activity of ____
Skeletal muscles; Lower motor neurons
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Somatic motor neurons are also called:
Alpha motor neurons
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Motor neurons that control limb and body movements are located in the ____ of the ___
Anterior horns of the spinal cord
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Somatic motor neurons synapse directly with:
Skeletal muscle and the NMJ
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What is a motor unit?
1 motor neuron plus all the muscle fibers that it innervates
A single motor neuron can branch at its axon terminal and innervate multiple fibers
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Motor units allow for:
Coordinated response of larger muscles
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A single muscle muscle fiber receives how many synapses? What does this mean?
One; Muscle cell is dependent on a single motor neuron for activation, providing great specificity for muscle control
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Motor unit pool
All the motor units within a muscle
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Motor units vary greatly in ____; a single somatic motor neuron may innervate ____ muscle fibers
Size; 3 to 2,000
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What is a small motor unit?
A single motor unit which innervated only a few muscle fibers
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Small motor units allow for:
Fine motor control in that muscle (ex. muscle that controls eye movement, fingers)
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What is a large motor unit?
A single motor unit which innervates thousands of muscle fibers
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Function of large motor unit
Coordinate the response of large muscles (ex. control large limb muscles, posture, walking)
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Different types of movements result from:
The activation of small and large motor units
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Motor unit recruitment: Increasing the number of motor units active at any one time increases ____
The amount of force produced by a muscle
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The progressive activation of motor units is called:
Recruitment
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The contraction of a whole muscle often require:
Hundreds of motor neurons to fire APs
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In what order are motor units recruited?
In a fixed order, according to their size
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True or false: Larger motor units are recruited and fire APs before smaller motor units are recruited
False: smaller before larger
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During motor unit recruitment, when synaptic input increases, what happens?
- Progressively larger motor units are recruited
- results in gradual increase in muscle contraction
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The orderly recruitment of motor neurons by size is known as:
Motor unit size principle
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Motor unit recruitment ____ the strength of muscle contraction
Increases
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AP frequency of motor neurons: frequency refers to ____
The number of APs delivered to a muscle within a set period of time
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An increase in the frequency of APs generated by motor neurons will:
Increase muscle contraction
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The increase in muscle force that occurs with increased AP frequency reflects the ____ of successive muscle contractions
Summation
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The muscle fibers are activated by the next AP before _____, and the forces generated by the temporally overlapping contractions are ____
They have had time to completely relax; Summed
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At the highest AP firing rated, summation grows stronger and individual muscle fibers become in a state of _____
Tetanus
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What is tetanus?
- state of sustained maximal muscle contraction
- also infectious disease caused by tetanospasmin
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True or false: muscle has time to relax between successive stimuli during tetanus
False
106
Tetanus infection generally occurs through:
Wound contamination and often involves a cut or deep puncture wound
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____ is the site of many interneurons and complex neural circuits that perform the nuts and bolts of processing motor control
Spinal cord
108
Spinal cord neurons can take charge of ____
Reflex movements
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What is a reflex?
Involuntary reaction in response to a stimulus applied to the periphery and transmitted to the CNS
110
_____ allow quicker reaction to stimuli than is possible by conscious thought
Reflexes
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3 classes of nerves are the basic constituents of all neural circuits
- sensory (afferent neurons)
- interneurons
- motor (efferent neurons)
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Components of a reflex arc are labeled in the order in which ____
AP;s pass through them
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Components of a reflex arc
- receptor
- sensory neuron
- interneuron
- motor neuron
- effector organ
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In a reflex arc, ___ synapses with the interneuron at the _____
Afferent nerve; dorsal root
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Proper control of muscle function requires:
- excitation of the muscle by the spinal cord anterior motor neurons
- continuous feedback of sensory information from each muscle to the spinal cord
116
Proprioception
Sense of the body's position in space based on specialized receptors that reside in the muscles and tendons
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Types of muscle receptors
- Muscle spindle
- Golgi tendon organ
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____ signals the changes in the length of a muscle
Muscle spindle receptor
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____ signals the amount of force being applied to a muscle
Golgi organ tendon receptor
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Muscle spindles are ____ that are located within _____
Sensory receptors; the muscle itself
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Function of muscle spindles is to:
Detect changes in muscle length and the speed of change in muscle length
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Muscle spindles are referred to as ____
Intrafusal fibers
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Each muscle contains ___ muscle spindles
Many
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True or false: muscles necessary for fine movements contain less spindles than muscles that are used for posture or coarse movements
False - contain MORE
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When muscles lengthen, what happens to muscle spindles?
They stretch
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Muscle spindle stretch causes ____. This results in ____
AP's to sent to the spinal cord; STRETCH REFLEX --> activation of more motor neurons at the spinal level that send an impulse back to the muscle, signals the muscle to contract with greater force to decrease the speed at which the muscle is being stretched
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Examples of stretch reflex
- maintain proper posture
- knee jerk test
- protection from potential damage
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Where is golgi tendon organ located?
Between muscle and tendon
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Golgi tendon organ (GTO) signals information about:
The load or force being applied to the muscle
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When a GTO is stimulated, it causes:
Associated muscle to relax by interrupting its contraction (autogenic inhibition)
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The function of the GTO can be considered ____ of the muscle spindle
Opposite (serves to produce muscle contraction)
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Swallowing reflex: can be initiated ____ but thereafter it is almost entirely under ____
Voluntarily; reflex control
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Phases of swallowing
- oral phase
- pharyngeal phase
- esophageal phase
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Oral phase of swallowing occurs ____ when the bolus of food is passed down towards the pharynx by ____
Voluntarily; elevating the tongue (a conscious decision)
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During the oral phase of swallowing, what nerves are activated?
- sensory nerves from CN 5 and 9 in the pharynx
- integration in the medulla initiated involuntary swallowing reflex
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Pharyngeal phase of swallowing occurs ____ when food enters the pharynx
Involuntarily
135
Esophageal phase of swallowing occurs ____ in the esophagus
Involuntarily
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Steps of pharyngeal phase swallowing
- activation of somatic and vagal nerved innervating skeletal muscle of pharynx; closes trachea
- inhibition of vagal nerves at upper esophageal sphincter causes relaxation of UES
- activation of vagal nerves innervating skeletal muscle of esophagus, causing a primary peristaltic contraction
136
Steps of esophageal phase of swallowing
- activation of vagal nerves innervating smooth muscle of the esophagus
- activation of enteric nerves leads to continued peristaltic waves along esophagus
- relation of the lower esophageal sphincter and receptive relaxation of the stomach
137
What does the gag reflex involve?
Brisk and brief elevation of the soft palate and contraction of the pharyngeal muscles
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Gag reflex is stimulated by:
Touching posterior pharyngeal wall
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Gag reflex: sensory limb mediated by ____; motor limb by ____
CN 9; CN 10
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Touching the soft palate can lead to ___
Similar reflex response as the gag reflex - sensory limb is CN V
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True or false: gag reflex rarely interferes with dental procedures
False - often
