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HAN 200 > Chapter 14 > Flashcards

Chapter 14 Flashcards

1
Q

Autonomic Nervous System

A

The ANS consists of motor neurons that:
->Regulate circulation, respiration, digestion, metabolism, secretions, body temp, and reproduction

  • > consists mostly of motor neurons
  • > make adjustments to ensure optimal support for body activities
  • > operate via subconscious control
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2
Q

Key differences between Somatic and Autonomic NS

A
  1. Effectors
  2. Efferent pathways (and their neurotransmitters)
  3. Target organ responses to neurotransmitters
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3
Q
  1. Differences in effectors
A

Somatic nervous system:
-> skeletal muscles

ANS:

  • > cardiac muscle
  • > smooth muscle
  • > glands
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4
Q
  1. differences in efferent (motor) pathways
A

Somatic nervous system:
-> A, thick, heavily myelinated somatic motor neuron (type A) makes up each pathway from the CNS to the muscle (faster)

ANS pathway is a two-neuron chain:
-> 1. Preganglionic neuron (in CNS) has a thin, lightly myelinated preganglionic axon

-> 2. Ganglionic neuron in autonomic ganglion has an unmyelinated postganglionic axon that extends to the effector organ

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5
Q
  1. Neurotransmitters of the ANS
A
  • > These include: acetylcholine, epinephrine, norepinephrine
  • > Neurons that secrete acetylcholine are called: cholinergic
  • > Neurons that secrete epinephrine and norepinephrine are called: adrenergic

What is the neurotransmitter of skeletal system?
->ACh

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6
Q
  1. Neurotransmitter Effects
A

Somatic nervous system:
->All somatic motor neurons release acetylcholine (ACh)

-> Effects are always stimulatory

ANS:

  • > Preganglionic fibers release ACh
  • > Postganglionic fibers release norepinephrine or ACh at effectors
  • > Effect is either stimulatory or inhibitory, depending on type of receptors
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7
Q

Somatic NS is much faster than ANS

A

TRUE! Somatic NS has a heavily myelinated axon

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8
Q

Divisions of the ANS

A
  1. Sympathetic division- mobilizes body
  2. Parasympathetic division- maintenance

Dual innervation:
-> Almost all visceral organs are served by both divisions, but they cause opposite effects

->Exception: sweat glands, arrector pili, adrenal medulla only have sympathetic innervation

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9
Q

Parasympathetic division

A
  • > “Rest and digest”
  • > promotes maintenance activities (homeostasis) and conserves body energy
  • > its activity is illustrated in a person who relaxes, reading, after a meal
  • > Blood pressure, heart rate, and respiratory rates are low
  • > Gastrointestinal tract activity is high
  • > Pupils are constricted and lenses are accommodated for close vision
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10
Q

Sympathetic Division

A
  • > “fight or flight”
  • > mobilizes the body during activity. promotes adjustments during excercise, or when threatened (stress)
  • > Blood flow is shunted to skeletal muscles and heart
  • > Bronchioles dilate
  • > Liver releases glucose, fuel needed
  • > Pupils dilate to see environment
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11
Q

Sympathetic division anatomy

A

Origin of fibers:
-> Thoracolumbar region of the spinal cord

Length of fibers:
-> short preganglionic and long postganglionic

Location of ganglia:
->close to spinal cord

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12
Q

Parasympathetic division anatomy

A

Origin of fibers:
-> Brain and sacral spinal cord (craniosacral)

Length of fibers:
-> long preganglionic and short postganglionic

Location of ganglia:
-> in visceral effector organs

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13
Q

Vagus NN has 90% of all preganglionic parasympathetic nerves

A

true

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14
Q

Sympathetic (Thoracolumbar) Division

A

Preganglionic neurons are in what spinal cord segments?
->T1 – L2 (thoracic & lumbar)

  • > Sympathetic neurons come from the lateral horns of the spinal cord
  • > Preganglionic fibers pass through the white rami communicantes and enter sympathetic trunk (paravertebral) ganglia
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15
Q

Sympathetic trunks and pathways

A

There are 23 paravertebral ganglia in the sympathetic trunk (chain). Upon entering a sympathetic trunk ganglion a preganglionic fiber may:

  1. Synapse with a postganglionic neuron within the same ganglion
  2. Ascend or descend the sympathetic trunk to synapse in another trunk ganglion
  3. Pass through the trunk ganglion and emerge without synapsing
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16
Q

Pathways with synapse in chain ganglia

A
  • > Preganglionic axons enter the sympathetic ganglia via the white rami communicantes (myelinated fibers).
  • > Postganglionic axons exit the sympathetic ganglia and enter the ventral rami via the gray rami communicates (unlyelinated)
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17
Q

what neurotransmitter is released between pre and post-ganglionic neuronS?

A

ACh

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18
Q

Sympathetic pathways

A
  • > To Head: face, stimulates dilators of eye, inhibit nasal and salivary glands.
  • > To Thorax: heart, lungs, esophagus, thyroid gland
  • > To collateral ganglia to form splanchnic n
  • > To abdomen: stomach, intestines, liver, spleen & kidneys
  • > To pelvic: large intestines, bladder, reproductive organs “anal retentive”
19
Q

Pathways with synapses in the adrenal gland

A
  • > Some preganglionic fibers pass directly to the adrenal medulla without synapsing
  • > Upon stimulation, medullary cells secrete norepinephrine and epinephrine into the blood
20
Q

Visceral reflexes

A
  • > Visceral reflex arcs have the same components as somatic reflexes
  • > Main difference: visceral reflex arc has two neurons in the motor pathway

What is an example of visceral reflexes?
->reflexes that empty the rectum and bladder

-> Visceral pain afferents travel along the same pathways as somatic pain fibers, contributing to the phenomenon of referred pain

21
Q

Referred pain

A
  • > Visceral pain afferents travel along the same pathway as somatic pain fibers
  • > Pain stimuli arising in the viscera are perceived as somatic in origin
  • > Explains why when someone is experiencing a heart attack they may have pain in their arm.
22
Q

Neurotransmitters

A

CHOLINERGIC fibers:

  • > release the neurotransmitter ACh
  • > Released from all ANS preganglionic axons
  • > Released from all parasympathetic postganglionic axons

ADRENERGIC fibers:

  • > release the neurotransmitter NE
  • > most sympathetic postganglionic axons
  • > Exceptions: sympathetic postganglionic fibers secrete ACh at sweat glands and some blood vessels in skeletal muscles
23
Q

Receptors for neurotransmitters

A
  1. CHOLinergic receptors for ACh (SNS & PNS)
    - > Nicotinic receptor
    - > muscarinic receptor
  2. ADRENergic receptors for NE (SNS)
    - > Alpha
    - > Beta
24
Q

Cholinergic Receptors

A

Two types of receptors bind ACh
1,. Nicotinic (always excitatory)
2. Muscarinic (either excitatory or inhibitory)

25
Q

Nicotinic receptors (ACh)

A

Found on:

  • > Motor end plates of skeletal muscle cells (NMJ)
  • > All post ganglionic neurons
  • > Hormone-producing cells of the adrenal medulla

Effect of ACh at nicotinic receptors is always stimulatory

26
Q

Muscarinic Receptors (ACh)

A

Found on:
->All effector cells (target organs) stimulated by postganglionic cholinergic fibers (mostly parasympathetic)

The effect of ACh at muscarinic receptors:

  • > Can be either inhibitory or excitatory
  • > Depends on the receptor type of the target organ
27
Q

Adrenergic receptors (NE binding)

A

Two types:

  • > Alpha (subtypes alpha 1, alpha 2)
  • > Beta (subtypes beta 1, beta 2 , beta 3)
  • > Effects of NE depend on which subclass of receptor predominates on the target organ
  • > Excitatory or inhibitory
  • > Just sympathetic NS
28
Q

Interactions of the autonomic division

A
  • > Most visceral organs have dual innervation
  • > Dynamic antagonism allows for precise control of visceral activity

Sympathetic division
-> increases heart & respiratory rates, and inhibits digestion and elimination; utilizes glucose and fat for fuel

Parasympathetic division:
-> decreases heart & respiratory rates, and allows for digestion & the discarding of wastes

29
Q

Sympathetic tone

A
  • > Sympathetic division controls blood pressure, even at rest
  • > Sympathetic tone (vasomotor tone)
  • > Alpha-blocker drugs interfere with vasomotor fibers and are used to treat hypertension
  • dominates blood vessels
30
Q

Parasympathetic tone

A

Parasympathetic division normally dominates the heart and smooth muscle of digestive and urinary tract organs

  • > Slows the heart
  • > Dictates normal activity levels of the digestive and urinary tracts

*The sympathetic division can override these effects during times of stress

31
Q

Unique roles of the sympathetic division

A

-> The adrenal medulla, sweat glands, arrector pili muscles, kidneys, and most blood vessels receive only sympathetic fibers

The sympathetic division controls:

  • > Thermoregulatory responses to heat
  • > Metabolic effects
  • Increases metabolic rates of cells
  • Raises blood glucose levels
  • Mobilizes fats for use as fuels
32
Q

Localized versus diffuse effects

A
  • > Parasympathetic division: short-lived, highly localized control over effectors, usually in control.
  • > Sympathetic division: long-lasting, body-wide (systemic) effects
33
Q

effects of sympathetic activation

A

Sympathetic activation is long lasting because NE:

  • > Is inactivated more slowly than ACh
  • > NE and epinephrine are released into the blood and remain there until destroyed by the liver

Explains why you need to calm down after a stressful situation

34
Q

Control of ANS functioning

A

Hypothalamus—main integrative center of ANS activity

Subconscious cerebral input via limbic lobe connections influences hypothalamic function

35
Q

Homeostatic imbalance of ANS

A
  • > Hypertension – may result from overactive sympathetic vasoconstrictor response promoted by continuous high levels of stress
  • > Raynaud’s disease – exaggerated vasoconstriction provoked by exposure to cold, causing skin of fingers and toes to become pale then cyanotic
36
Q

Hypothalamic control

A

Centers of the hypothalamus control, main integrative center for ANS control:
->Heart activity and blood pressure

  • > Body temperature, water balance, and endocrine activity (pituitary gland)
  • > Emotional stages (rage, pleasure) and biological drives (hunger, thirst, sex)
  • > Reactions to fear and the “fight-or-flight” system
37
Q

Sympathetic NS

A
  • > Vasoconstrict blood vessels in skin and gut to increase blood flow to the muscles
  • > increase blood glucose
  • > dilate bronchi
  • > increase blood pressure, heart rate
  • > reduce activity in digestive system
38
Q

Parasympathetic NS

A
  • > slows heart rate, decreases contraction force
  • > facilitates digestion
  • > bronchoconstriction
  • > controls voiding of bowel and bladder
  • > sexual function
39
Q

preganglionic neurons

A

the midbrain, pons, and medulla oblongata contain parasympathetic nuclei associated with cranial nerves III, VII, IX, and X

40
Q

The first set, called preganglionic neurons, originates in the brainstem or the spinal cord, and the second set, called ganglion cells or postganglionic neurons, lies outside the central nervous system in collections of nerve cells called autonomic ganglia.

A

yes

41
Q

sympathetic release ACh at pre and NE at postganglionic axons

A

yes

42
Q

parasympathetic release ACh at both pre and post ganglionic axons

A

yes

43
Q

ANS

A
  • involuntary
  • regulates internal organs
  • effectors: cardiac muscle, smooth muscle, glands
  • 2 neurons from CNS to effector
  • neurotransmitter: ACh at site or NE into blood stream
44
Q

Somatic NS

A

-voluntary
-regulates movement
-effectors: skeletal muscle
-1 neuron from CNS to effector
Neurotransmitter: ACh at neuromuscular junction

HAN 200 (15 decks)

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