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Flashcards in Chapter 14 Deck (34)
1

Autonomic Nervous System (ANS)

Motor neurons that:
-Innervate smooth muscle cardiac muscle, and glands
-Make adjustments to ensure optimal support for body activities
-Operate via subconscious control
Involuntary Nervous System: Fight-or-Flight

2

Somatic Versus Autonomic Nervous Systems

Both have motor fibers
Differences
-Effectors
-Efferent pathways and ganglia
-Target organ responses to neurotransmitters

3

Effectors

Somatic nervous system
-Skeletal muscles
Autonomic Nervous System
-Cardiac muscle
-Smooth muscle
-Glands

4

Efferent Pathways and Ganglia

Somatic Nervous System
-Cell body in CNS
-Thick, myelinated fibers
-Spinal or cranial nerve to skeletal muscle

5

Autonomic Nervous System Pathway uses 2-Neuron Chain

1. Pre-ganglionic Neuron
-In CNS has a thin lightly myelinated axon
2. Post-ganglionic Neuron
-Autonomic ganglion outside CNS
-Nonmyelinated axon extends to effector organ

6

Neurotransmitter Effects: Somatic Nervous System

-All somatic motor neurons release acetylcholine (ACh)
-Effects always stimulatory

7

Neurotransmitter Effects: Autonomic Nervous System

Pre-ganglionic fiber release ACh
Post-ganglionic fibers release norepinephrine or ACh at effectors
Effect is either stimulatory of inhibitory, depending on type of receptors

8

Overlap of Somatic and Autonomic Function

Most spinal and many cranial nerves contain both somatic and autonomic fibers
Adaptations usually involve both skeletal muscles and visceral organs

9

Divisions of the Autonomic Nervous System

Sympathetic division
Parasympathetic division
Dual innervation

10

Dual Innervation

All visceral organs served by both divisions but cause opposite effects

11

Role of Parasympathetic Division

Maintenance activities and conserves body energy
-Directs digestion
Person relaxing and reading after a meal
-low BP and Heart Rate
-Gastrointestinal tract activity high
-Pupils constricted

12

Role of Sympathetic Division

Mobilizes body during activity "Fight or Flight" system
-Exercise
-Excitement
-Emergency
-Embarrassment
Increased BP and Heart Rate, Tensed

13

Role of the Sympathetic Division During Vigorous Physical Activity

Shunts blood to skeletal muscles and heart
Dilates bronchioles
Causes liver to release glucose
Run away to survive

14

Sympathetic Trunks and Pathways

Paravertebral ganglia vary in size, position, and number
There are 23 paravertebral ganglia in the sympathetic trunk (chain)
-3 Cervical
-11 Thoracic
-4 Lumbar
-4 Sacral
-1 Coccygeal

15

Pathways with Synapses in Trunk Ganglia: Fibers that Innervate

Sweat Glands
Arrector Pili Muscles
Vascular Smooth Muscle

16

Pathways to Head

Fibers synapse in the superior cervical ganglion
These fibers:
-Innervate skin and blood vessels of the head
-Stimulate dilator muscles of the iris
-Inhibit nasal and salivary glands
-Innervate smooth muscle of upper eyelid
-Branch to heart

17

Pathways to Thorax

These Fibers Innervate:
-Heart vis the cardiac plexus
-Thyroid gland and the skin
-Lungs and esophagus

18

Pathways to Abdomen

Post-ganglionic fibers serve the stomach, intestines, liver, spleen, and kidneys

19

Pathways to Pelvis

Post-ganglionic fibers serve the distal half of large intestine, the urinary bladder, and the reproductive organs
Primarily inhibit activity of muscles and glands in abdominopelvic visceral organs

20

Pathways with Synapses in the Adrenal Medulla

Upon stimulation, medullary cells secrete norepinephrine and epinephrine into blood

21

Visceral Pain

Visceral pain afferent travel along same pathways as somatic pain fibers, contributing to phenomenon of referred pain

22

Neurotransmitter

Cholinergic Fibers
Adrenergic Fibers

23

Cholinergic Fibers

Release ACh
-All ANS pre-ganglionic axons
-All parasympathetic post-ganglionic axons at effector synapse

24

Adrenergic Fibers

Release Norepinephrine
-Most sympathetic post-ganglionic axons

25

Interactions of the Autonomic Divisions

Most visceral organs have dual innervation
Dynamic antagonism allows for precise control of visceral activity
-Sympathetic division increase heart and respiratory rates, and inhibits digestion and elimination
-Parasympathetic division decreases heart and respiratory rates, and allows for digestion and discarding wastes

26

Sympathetic Division

Long
Body Wide Effects

27

Parasympathetic Division

Short
Localized

28

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

29

Hypothalamic Controls

Control may be direct or indirect

30

Centers of Hypothalamus Controls

Heart activity and blood pressure
Body temperature, water balance, and endocrine activity
Emotional stages (rage, pleasure) and biological drives (hunger, thirst, sex)
Reactions to fear and "fight or flight" system

31

Cortical Controls

Connections of hypothalamus to limbic lobe allow cortical influence on ANS
Voluntary cortical control of visceral activities is possible

32

Biofeedback of Cortical Controls

Awareness of physiological conditions with goal of consciously influencing them
Training allows some to control migraines and manage stress

33

Homeostatic Imbalances of ANS

Hypertension
Raynaud's Disease
-pale than cold fingers
Autonomic Dysreflexia
-High BP and life threatening

34

Developmental of Aspects of the ANS

Older Age
-Dry eyes
-Constipation
-Low BP