ch 12-15 Flashcards by Abbie Valicevic

For how many sensory modalities can a given sensory neuron typically carry information?

one

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Which mechanoreceptor in the skin detects touch and low frequency vibration?

meissner’s corpuscle

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Which mechanoreceptor in the skin detects movements that disturb hairs?

hair root plexus

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Which mechanoreceptor in the skin detects continuous touch

Merkel’s disk

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Which mechanoreceptor in the skin detects skin stretching?

Ruffini corpuscle

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Which mechanoreceptor in the skin detects high frequency vibration?

Pacinian corpuscle

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first pain

sharp, alpha-gamma fibers

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second pain

duller and longer lasting, C fibers

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warm receptor fibers

C fibers

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cold receptor fibers

A and C fibers

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somatic sensory pathway neuron locations

first- receptors to spinal cord/brainstem
second- spinal cord/brainstem to thalamus (decussate)
third- thalamus to primary somatosensory cortex

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Dorsal column-medial lemniscus pathway

-touch, proprioception
-dorsal root ganglia –> medulla –> thalamus

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spinothalamic pathway

-pain, temp
- dorsal root ganglia –> posterior gray horn –> thalamus

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somatosensory cortex

Brodman’s 1, 2, 3 (postcentral)

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axial muscles

responsible for trunk movements

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appendicular muscles

support, move, and brace limbs

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lower motor neurons

somatic motor neurons in lower CNS that innervate skeletal muscles

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LMN cell bodies in anterior gray horn

dorsal = flexors
ventral = extensors
medial = axial
lateral = distal

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Lower motor neurons that innervate upper limb muscles have their cell bodies in the _______ enlargement. Their axons exit the spinal cord via a ______ root.

cervical, ventral

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In the somatic motor pathways, ___________ have their cell bodies in the spinal cord and brainstem and extend axons directly to skeletal muscles via spinal and cranial nerves.

lower motor neurons

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Lower motor neurons that innervate lower limb muscles have their cell bodies in the _______ enlargement. Their axons exit the spinal cord via a ______ root.

lumbar, ventral

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major inputs to an alpha motor neuron

Dorsal root ganglion cells with axons that innervate a muscle spindle
Upper motor neurons in the motor cortex and brain stem
Spinal interneurons

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motor neuron pool

all alpha motor neurons that innervate one muscle

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Slow (S) oxidative fibers

Relatively slow to contract
Sustain contraction for a long time without fatigue (legs and torso)
Dark red color (contain large amount of myoglobin and many capillaries)
Large number of mitochondria

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Fast (F) fibers

- Contract rapidly - Fatigue more quickly (arm muscles) - White color (fewer myoglobin and capillaries) - Fewer mitochondria

Patellar (knee jerk) reflex arc

Quadriceps femoris muscle spindle → Ia axon → alpha motor neuron → quadriceps femoris muscle

Tension that a single muscle fiber can produce depends on the ______ of action potentials of an alpha motor neuron that innervates the muscle fiber.

frequency

Muscle spindles are innervated by _____ sensory axons and _____ motor neurons.

Ia, gamma

When a limb withdraws from a painful stimulus, the contralateral limb compensates for the imposed extra-load by contracting extensors and relaxing flexors. This reflex is called _______.

crossed extensor reflex

lateral pathways

corticospinal and rubrospinal

corticospinal pathway

Motor cortex → internal capsule → cerebral peduncle → pyramid → lower motor neurons

rubrospinal pathway

Axons from red nucleus to lower motor neurons

ventromedial pathways

vestibulospinal, tectospinal, and reticulospinal

vestibulospinal pathway

Axons from vestibular nuclei (medulla) to lower motor neurons

tectospinal pathway

Axons from superior colliculus (midbrain) to lower motor neurons

reticulospinal pathway

Axons from reticular formation to lower motor neuron

which brodman's area is the primary motor cortex?

which brodman's area is the higher motor area?

features of the primary motor cortex

- Sends motor commands through the corticospinal tracts to the spinal cord. - Is located in the precentral gyrus of the frontal lobe. - Contains “motor homunculus”, which represents a map of brain areas dedicated to motor functions for different anatomical divisions of the body

The ________ and prefrontal cortex represent the highest levels of motor control hierarchy. They make decisions about what actions to take and their likely outcome.

posterior parietal cortex

The ________ and prefrontal cortex represent the highest levels of motor control hierarchy. They make decisions about what actions to take and their likely outcome.

mirror neurons

structures of the basal ganglia

- Globus pallidus - Putamen - Caudate nucleus

basal ganglia functions

- Regulate initiation and termination of movements - Facilitate behavior and movements that are appropriate and inhibit inappropriate movements - Control subconscious contractions of skeletal muscles - Regulate muscle tone

direct neural pathway

Enhance initiation of desired movements

indirect neural pathway

Suppresses competing and inappropriate motor programs

Parkinson's symptoms

- Hypokinesia: paucity of movement - Bradykinesia: slowness of movement - Akinesia: inability to move muscles voluntarily - Rigidity: increased muscle tone - Tremors of jaw and hands

Parkinson's cause and treatment

degeneration of dopaminergic neurons in substantia nigra; L-dopa (produces dopamine)

Huntington's symptoms

- Hyperkinesia: excessive movement - Dyskinesia: abnormal movement - Chorea - Dementia - Personality disorders

Huntington's cause

loss of neurons in caudate nucleus, putamen, and globus pallidus (basal ganglia)

granule cells

Excitatory, most numerous neuron type in CNS

purkinje cells

inhibitory

cerebellar functions

- Coordination of movement - Motor learning - Equilibrium (posture and balance)

symptoms of cerebellar lesions

- Ataxia: uncoordinated movement - Dyssynergia: decomposition of movement - Dysmetria: inability to estimate distance in muscular action

The sensorimotor cortex sends massive axon projections to the _________, which relay(s) the information to the cerebellum.

pons

___________ neurosecretory neurons in the __________ hypothalamus extend axons to the posterior lobe of the pituitary gland and secrete neurohormones (oxytocin and vasopressin (antidiuretic hormone, ADH).

Magunocellular; posterior

___________ neurons in the __________ hypothalamus secrete hypophysiotropic hormones (FSH, LH, TSH, etc)

Parvocellular; anterior

The _________ nervous system mostly controls voluntary movements of skeletal muscles, whereas the __________ nervous system usually regulates involuntary movements of cardiac and smooth muscles.

somatic; autonomic

Somatic motor pathways consist of ____ neuron, while the ANS motor pathways consist of _______ neurons in ______

one; two; series

sympathetic

fight or flight

parasympathetic

rest and digest

enteric

controls GI behavior

cholinergic receptors

nicotinic = postganglionic muscarinic = effectors (most sweat glands)

adrenergic receptors

alpha 1 and 2; beta 1, 2, and 3 - 1s are excitatory and cause constriction - 2s are inhibitory and cause relaxation

SNS neurotransmitters

preganglionic = ACh (nicotinic) postganglionic= NE

adrenal medulla neurotransmitters

preganglionic = ACh (nicotinic) postganglionic = epinephrine, NE (chromaffin cells)

sweat gland neurotransmitters

preganglionic = ACh (nicotinic) postganglionic= ACh (muscarinic)

PNS neurotransmitters

preganglionic = ACh (nicotinic) postganglionic= ACh (muscarinic)

fight or flight

- Pupils dilate - Heart rate and BP increase - Airways dilate - Blood vessels dilate - Constrict to kidneys and GI tract - Glycogenolysis in liver, lipolysis in adipose tissue

rest and digest

decrease in heart rate, airway diameter, pupil diameter (constrict)

phenylephrine - agonist

Used in cold and sinus meds - Constricts blood vessels to reduce mucus production

atropine - anatagonist

Muscarinic ACh receptor antagonist - Dilated pupils - Reduces glandular secretions - Relaxes smooth muscle in GI tract

beta blockers - antagonist

Treats hypertension - Decreases heart rate and force of contractions

NE system

Locus coeruleus in the pons

serotonin system

Raphe nuclei in brainstem, rostral nuclei in pons and midbrain, caudal nuclei in medulla

dopamine system

Dopaminergic neurons in diffuse modulatory systems

ACh system

Diffuse modulatory cholinergic systems