Chapter 15 & 16 - ANS & Sensory, Motor & Integrative Systems Flashcards Preview

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Flashcards in Chapter 15 & 16 - ANS & Sensory, Motor & Integrative Systems Deck (59):
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(2) divisions of ANS

sympathetic 

parasympathetic

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Structure of the Sympathetic Division

thorocolumbar (sympathetic) division- Preganglionic neurons originate from thoracic lumbar levels of spinal cord (T1-L2). 

 

Sympathetic ganglia - site of synapse between sympathetic pre & postganglionic 

(2) types - sympathetic trunk & prevertebral (collateral) ganglia

 

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Preganglionic & postganglionic neurons

preganglionic - cell body in CNS, exits as cranial/spinal nerve 

axon = type B fiber (small, myelinated)

postganglionic - in PNS (outside CNS), cell body & dendrites in autonomic ganglia 

axon = small, unmyelinated type C fiber 

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Sympathetic division 

sympathetic ganglia (2) 

Sympathetic trunk (vertebral chain) ganglia. - innervate organs above diaphragm 


Prevertebral (collateral) ganglia: celiac, superior mesenteric, inferior mesenteric, 
aorticorenal and renal.

innervate organs below diaphragm

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Once axons of sympathetic preganglionic neurons pass to sympathetic trunk ganglia, they may connect with postganglionic neurons in the following ways (4) 

1) synapse with neurons in nearest gangliaon

2) axons ascend/descend to higher/lower ganglion, sympathetic chains 

3) through sympathetic trunk ganglion to synapse with neurons in prevertebral ganglion

4) through sympathetic trunk & prevertebral to chromaffin cells of adrenal medulla 

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A single sympathetic preganglionic fiber has many axon _______________ and may synapse with 20 or more postganglionic neurons. 

 

branches (collaterals) 

 

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sympathetic postganglionic axons typically terminate in several 

visceral effectors 

therefore effects are more widespread than parasympathetic stimulation

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Structure of the Parasympathetic Division 

 

craniosacral divison - Preganglionic neurons originate from cranial 
nerves III, VII, IX, X & sacral spinal nerves S2-S4

parasympathetic ganglia - preganglionic synapse with postganglionic in terminal (intramural) ganglia 

 

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Parasympathetic Presynaptic neuron usually synapses with 4-5 postsynaptic neurons all of which supply ?

a single visceral effector

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Autonomic Plexuses in Thorax, Abdomen & Pelvis

network of sympathetic & parasympathetic neurons 

thorax plexus - heart

pulmonary plexus - bronchial tree

celiac (solar) plexus - largest. stomach, spleen, pancreas, liver, gallbladder & adrenal medulla

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Sympathetic response

fight or flight

 ↑ ATP, heart rate, BP, blood supply to skeletel/cardiac muscles, liver & fat, blood glucose

dilation of pupils, constriction of blood vessels 

breakdown of glycogen & lipids

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Parasympathetic Responses

rest & digest

conserve & restore energy 

 ↑ digestive & urinary function

↓ body functions supporting physical activity 

 

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Sensation

conscious & subconscious awareness of changes in environment 

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components of sensation

Stimulation of sensory receptor → transduction of stimulus → nerve impulses integration of sensory input. 

 

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Classification of Sensory Receptors

General senses

Special Senses

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  1. General senses
  2. Special senses

1) somatic & visceral 

a. somatic - tactile, thermal, pain &proprioceptive sensations

b. Visceral- provide info about conditions within internal organs. 

2) smell, taste, vision, hearing, equilibrium/balance

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Types of Sensory Receptors

free nerve endings

encapsulted nerve endings

seperate cells

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free nerve endings

pain & thermoreceptors

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encapsulated nerve endings

dendrites enclosed in CT capsule

pacinian corpuscles

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seperate cells 

hair cells, photoreceptors & gustatory receptor cells

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Generator Potential and Receptor Potential 

 

Generator potential: produced by free nerve, encapsulated nerve endings, and olfactory receptors. When it reaches threshold, triggers 1+ nerve impulses in axon of  first-order sensory neuron. 


Receptor potential triggers release of neurotransmitterspostsynaptic potential → action potential. 

 

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Classification of Sensory Receptors Based on the Location

o Exteroceptors: external surface
o Interoceptors: internal environment (vessels, organs & muscles & NS) 
o Proprioceptors: muscles, tendons, joints & nner ear 

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Classification of Sensory Receptors based on the type of Stimulus

mechanoreceptors - mechanical stimuli (touch, proprioception) 

thermoreceptors

nociceptors - pain

photoreceptors - light

chemoreceptors - chemicals in mouth, nose & body fluids

Osmoreceptors 

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Adaptation of Sensory Receptors 

 

rapidly adapting receptors:  detect pressure, touch and smell. 

slowly adapting receptors: detect pain, body position & blood chemical composition

 

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Somatic Sensations 

(4) modalities 

 

sensory receptors in skin, muscles, tendons, joints & inner ear 

1) tactile 

2) thermal

3) pain

4) proprioceptive 

 

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Tactile Sensations 
include?

touch

pressure 

vibration

itch 

tickle

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Tactile receptors in skin

Meissner corpuscles

hair root plexuses

Merkel discs

Ruffini corpuscles

pacinian corpuscles

free nerve endings. 

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Meissner Corpuscles or Corpuscles of Touch 

 

egg-shaped mass of dendrites enclosed by capsule of CT

rapidly adapting 

dermal papillae of hairless skin 

 

TOUCH & PRESSURE

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Hair root plexuses

rapidly adapting- touch 

in hairy skin

free nerve endings wrapped around hair follicles 

detect movement on skin that disturbs hair

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Merkel Discs or Tactile Discs 

 

type I cutaneous mechanoreceptors

slowly adapting touch 

fingertips, hands, lips, external genitals

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Ruffini Corpuscles

type II cutaneous mechanoreceptors

elongated, encapsulated receptors 

deep in dermis, ligaments & tendons

hands & soles

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Pacinian or Lamellated Corpuscles 

 

Large oval structure composed of a multilayered CT capsule that encloses a dendrite (encapsulated)

fast adapting - pressure

joints, tendons, muscles, peiosteum, mammary glands, external genitals, pancreas & urinary bladder

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Thermal Sensations

thermoreceptors

cold - stratum basale: medium myelinated A fibers

warm - dermis: small unmyelinated C

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Pain Sensations 

protective

nociceptors 

free nerve endings 

fast: acute, sharp/pricking

slow: chronic, aching

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Refered pain

Pain is felt in or just deep to the skin that overlies the stimulated organ or in a surface area far from the stimulated organ

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Proprioceptive Sensations 

 

proprioceptors

slow adaptation

weight discrimation

(3) types: muscle spindles, tendon organs & joint kinesthetic receptors 

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Proprioceptors: muscle spindles

parellel to & among skeletal muscle fibers

measure muscle length

consist of intrafusal (inside) muscle fibers - specialized with sensory nerve endings & gamma motor neurons

extrafusal (outside) muscle fibers - surround muscle fiber supplied by alpha motor neurons

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Tendon Organs

at junction of tendon & muscle

protect tendons from damage due to xs tension

thin capsule of CT that encloses few tendon fascicles 

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Joint Kinesthetic Receptors

Found within or around articular capsules of synovial joints. 
Free nerve endings & Ruffini corpuscles respond to pressure

pacinian corpuscles respond to accel/deceleration of joints during movement

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Somatic Sensory Pathways 

  1. first order neurons 
  2. second order neuron 
  3. third order neuron

  1.  (somatic receptor → brain stem/spinal cord
  2. brain stem/spinal cord → thalamus
  3. thalamus → primary somatosensory area

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Major Somatic sensory pathways 

o The posterior column-medial lemniscus pathway. 
o The anterolateral (spinothalamic) pathway. 
o The trigeminothalamic pathway. 
o The anterior and posterior spinocerebellar pathway. 

 

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The Posterior Column-Medial Lemniscus Pathway 

 

impulses for touch, pressure, vibration, conscius proprioception from limbs, trunk, neck, & posterior head to cerebral cortex

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The Anterolateral (spinothalamic) pathway 

 

pain, cold , warmth, itch, & tickle from the limbs, trunk, neck, and posterior head to cerebral cortex.

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Trigeminothalamic Pathway 

 

most somatic sensations 

from face, nasal/oral cavity & teeth to cerebral cortex 

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Somatic Motor Pathways 

 

upper motor neurons → lower motor neurons → 
skeletal muscles

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Neural circuits involving basal ganglia and cerebellum regulate activity of  
_______________ motor neurons.

upper

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Organization of the Upper Motor Neuron Pathways 

direct motor pathway 

originates in cerebral cortex 

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Direct Motor pathways (2) 

corticospinal - limbs & trunk

corticobulbar - skeletal muscles in head

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 Indirect motor pathway-

originates in brain stem 

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 Indirect or Extrapyramidal Pathways (4) 

Rubrospinal tract 
- Tectospinal tract 
- Vestibulospinal tract 
- Reticulospinal tract 

 

 

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Modulation of Movement from the Cerebellum

coordinates and smoothes contractions of skeletal
muscles during skilled movements & helps maintain posture and balance

 

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Integrative Functions of the Cerebrum 

 

wakefulness, sleep, learning, memory 

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o The role of Reticular Activating System (RAS) in Awakening 

 

neuronal axons from reticular formation through thalamus to cerebral cortex

increased activity = awakening 

 

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Sleep

(2) components

state of altered consciousness

1) NREM

2) REM

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4 stages of sleep

  1. relaxed
  2. light sleep
  3. moderately deep sleep
  4. deepest sleep (sleepwalking)

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Learning

ability to acquire new info/skills through instruction/experience

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Memory

 process by which information acquired through learning is stored and retrieved. 

 

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Memory types (3) 

immediate

short-term 

long-term

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