the autonomic nervous system n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
The Autonomic Nervous System PowerPoint Presentation
Download Presentation
The Autonomic Nervous System

Loading in 2 Seconds...

play fullscreen
1 / 26

The Autonomic Nervous System - PowerPoint PPT Presentation


  • 114 Views
  • Uploaded on

The Autonomic Nervous System. Autonomic Nervous System (ANS). ANS consists of motor neurons that Innervate smooth and cardiac muscle, and glands Make adjustments to ensure optimal support for body activities Operate via subconscious control

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'The Autonomic Nervous System' - reid


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
autonomic nervous system ans
Autonomic Nervous System (ANS)
  • ANS consists of motor neurons that
    • Innervate smooth and cardiac muscle, and glands
    • Make adjustments to ensure optimal support for body activities
    • Operate via subconscious control
  • Also called involuntary nervous system or general visceral motor system

MDufilho

slide3

Figure 14.1 Place of the ANS in the structural organization of the nervous system.

Central nervous system (CNS)

Peripheral nervous system (PNS)

Motor (efferent) division

Sensory (afferent)

division

Somatic nervous

system

Autonomic nervous

system (ANS)

Parasympathetic

division

Sympathetic

division

MDufilho

somatic versus autonomic nervous systems
Somatic Versus Autonomic Nervous Systems
  • Both have motor fibers
  • Differ in
    • Effectors
    • Efferent pathways and ganglia
    • Target organ responses to neurotransmitters

MDufilho

slide5

Figure 14.2 Comparison of motor neurons in the somatic and autonomic nervous systems.

Neurotransmitter

at effector

Effector

organs

Cell bodies in central

nervous system

Peripheral nervous system

Effect

Single neuron from CNS to effector organs

ACh

+

SOMATIC

NERVOUS

SYSTEM

Stimulatory

Heavily myelinated axon

Skeletal muscle

Two-neuron chain from CNS to effector organs

NE

ACh

Nonmyelinated

postganglionic axon

SYMPATHETIC

Lightly myelinated

preganglionic axons

Ganglion

Epinephrine and

norepinephrine

+

ACh

Stimulatory

or inhibitory,

depending

on neuro-

transmitter

and receptors

on effector

organs

AUTONOMIC NERVOUS SYSTEM

Blood vessel

Adrenal medulla

ACh

ACh

Smooth muscle

(e.g., in gut), glands,

cardiac muscle

PARASYMPATHETIC

Nonmyelinated

postganglionic

axon

Lightly myelinated

preganglionic axon

Ganglion

Acetylcholine (ACh)

Norepinephrine (NE)

MDufilho

role of the parasympathetic division d activities
Role of the Parasympathetic Division – D activities
  • Promotes maintenance activities and conserves body energy
    • Directs digestion, diuresis, defecation
  • As in person relaxing and reading after a meal
    • Blood pressure, heart rate, and respiratory rates are low
    • Gastrointestinal tract activity high
    • Pupils constricted; lenses accommodated for close vision

MDufilho

role of the sympathetic division e activities
Role of the Sympathetic Division – E activities
  • Mobilizes body during activity; "fight-or-flight" system
  • Exercise, excitement, emergency, embarrassment
    • Increased heart rate; dry mouth; cold, sweaty skin; dilated pupils
  • During vigorous physical activity
    • Shunts blood to skeletal muscles and heart
    • Dilates bronchioles
    • Causes liver to release glucose

MDufilho

slide8

Figure 14.3 The subdivisions of the ANS.

Parasympathetic

Sympathetic

Eye

Eye

Brain stem

Skin*

Salivary

glands

Cranial

Salivary

glands

Sympathetic

ganglia

Heart

Cervical

Lungs

Lungs

T1

Heart

Stomach

Thoracic

Pancreas

Stomach

Liver

and gall-

bladder

Pancreas

L1

Adrenal

gland

Liver and

gall-

bladder

Lumbar

Bladder

Bladder

Genitals

Genitals

MDufilho

Sacral

application
Application
  • Work as a group on chart

MDufilho

neurotransmitters
Neurotransmitters
  • Cholinergic fibers release neurotransmitter ACh
    • All ANS preganglionic axons
    • All parasympathetic postganglionic axons at effector synapse
  • Adrenergic fibers release neurotransmitter NE
    • Most sympathetic postganglionic axons
    • Exception: sympathetic postganglionic fibers secrete ACh at sweat glands

MDufilho

slide11

Figure 14.2 Comparison of motor neurons in the somatic and autonomic nervous systems.

Neurotransmitter

at effector

Effector

organs

Cell bodies in central

nervous system

Peripheral nervous system

Effect

Single neuron from CNS to effector organs

ACh

+

SOMATIC

NERVOUS

SYSTEM

Stimulatory

Heavily myelinated axon

Skeletal muscle

Two-neuron chain from CNS to effector organs

NE

ACh

Nonmyelinated

postganglionic axon

SYMPATHETIC

Lightly myelinated

preganglionic axons

Ganglion

Epinephrine and

norepinephrine

+

ACh

Stimulatory

or inhibitory,

depending

on neuro-

transmitter

and receptors

on effector

organs

AUTONOMIC NERVOUS SYSTEM

Blood vessel

Adrenal medulla

ACh

ACh

Smooth muscle

(e.g., in gut), glands,

cardiac muscle

PARASYMPATHETIC

Nonmyelinated

postganglionic

axon

Lightly myelinated

preganglionic axon

Ganglion

Acetylcholine (ACh)

Norepinephrine (NE)

MDufilho

cholinergic receptors
Cholinergic Receptors
  • Two types of receptors bind ACh
    • Nicotinic – always stimulatory
    • Muscarinic – both stimulatory and inhibitory depending on the organ
  • Named after drugs that bind to them and mimic ACh effects

MDufilho

adrenergic receptors
Adrenergic Receptors
  • Two major classes
    • Alpha () (subtypes 1, 2)
    • Beta () (subtypes 1, 2 , 3)
  • Effects of NE depend on which subclass of receptor predominates on target organ

MDufilho

effects of drugs
Effects of Drugs
  • Epinephrine (adrenaline)
    • Hormone released or drug
    • Sympathomimetic effect
    • Hormone is released during “flight or fight”
    • Given as drug during heart attacks and anaphylactic shock - improve blood pressure and circulation
    • Binds to all adrenergic receptors (1, 2, 1, 2 , 3) – mimicks effect of NE
    • Active ingredient in OTC inhalers

MDufilho

effects of drugs1
Effects of Drugs
  • Albuterol – Proventil or Ventolin
    • Sympathomimetic effects – selective
    • Binds to 2 receptors – dilation of bronchioles
    • Given to asthma patients – relieves bronchospasms

MDufilho

effects of drugs2
Effects of Drugs
  • Propanolol (Inderal)
    • Sympatholytic effects
    • Rx as a “beta blocker to control hypertension
    • Vessels of skin and viscera receive constant impulses from sympathetic neurons – sympathetic tone
    • Action - decrease the number of sympathetic impulses from medulla to blood vessels – vasodilation and reduced blood pressure
    • Action – Binds and blocks NE receptors to heart – decreases heart rate to reduce cardiac output and BP

MDufilho

effects of drugs3
Effects of Drugs
  • Atropine
    • Anticholinergic; blocks muscarinic ACh receptors
    • Used to prevent salivation during surgery, and to dilate pupils for examination
  • Neostigmine
    • Inhibits acetylcholinesterase that breaks down ACh
    • Used to treat myasthenia gravis

MDufilho

effects of drugs4
Effects of Drugs
  • Over-the-counter drugs for colds, allergies, and nasal congestion
    • Stimulate -adrenergic receptors
  • Beta-blockers
    • Drugs that attach to 2 receptors to dilate lung bronchioles in asthmatics; other uses
  • See Table 14.3 p. 535

MDufilho

sympathetic tone
Sympathetic Tone
  • Sympathetic division controls blood pressure, even at rest
  • Vascular system ~ entirely innervated by sympathetic fibers
  • Sympathetic tone (vasomotor tone)
    • Keeps blood vessels in continual state of partial constriction

MDufilho

sympathetic tone1
Sympathetic Tone
  • Sympathetic fibers fire more rapidly to constrict blood vessels and cause blood pressure to rise
  • Sympathetic fibers fire less rapidly to prompt vessels to dilate to decrease blood pressure
  • Alpha-blocker drugs interfere with vasomotor fibers
    • Used to treat hypertension

MDufilho

parasympathetic tone
Parasympathetic Tone
  • Parasympathetic division normally dominates heart, smooth muscle of digestive and urinary tract organs, activate most glands except for adrenal and sweat glands
    • Slows the heart
    • Dictates normal activity levels of digestive and urinary tracts
  • The sympathetic division can override these effects during times of stress
  • Drugs that block parasympathetic responses increase heart rate and cause fecal and urinary retention

MDufilho

control of ans function
Control of ANS Function
  • Hypothalamus—main integrative center of ANS activity
  • Subconscious cerebral input via limbic system structures on hypothalamic centers
  • Other controls come from cerebral cortex, reticular formation, and spinal cord

MDufilho

slide23

Figure 14.8 Levels of ANS control.

Communication at

subconscious level

Cerebral cortex

(frontal lobe)

Limbic system

(emotional input)

Hypothalamus

The “boss”: Overall

integration of ANS

Brain stem

(reticular formation, etc.)

Regulates pupil size, heart,

blood pressure, airflow,

salivation, etc.

Spinal cord

Reflexes for urination,

defecation, erection,

and ejaculation

MDufilho

homeostatic imbalances of the ans
Homeostatic Imbalances of the ANS
  • Hypertension (high blood pressure)
    • Overactive sympathetic vasoconstrictor response to stress
    • Treated with adrenergic receptor - blocking drugs
  • Raynaud's disease
    • Exaggerated vasoconstriction in fingers and toes
      • Pale, then cyanotic and painful
      • Treated with vasodilators

MDufilho

homeostatic imbalances of the ans1
Homeostatic Imbalances of the ANS
  • Autonomic dysreflexia
    • Uncontrolled activation of autonomic neurons in quadriplegics and those with spinal cord injuries above T6
    • Blood pressure skyrockets
    • Life-threatening

MDufilho

developmental aspects of the ans
Developmental Aspects of the ANS
  • Effects of age on ANS
    • Constipation
    • Dry eyes
    • Frequent eye infections
    • Orthostatic hypotension
      • Low blood pressure after position change
      • Pressure receptors less responsive to blood pressure changes
      • Cardiovascular centers fail to maintain healthy blood pressure

MDufilho