1. Autonomic vs somatic efferent systems
Autonomic division
Antagonistic controls
Control of cardiac, smooth muscle, and glands in homeostasis
Agonists and antagonists in research and medicine
Somatic motor division
CNS control of skeletal muscles through neuromuscular junctions

2. Autonomic Division: Homeostasis
Antagonistic branches
Parasympathetic
“Rest and digest”
Restore body function
Sympathetic
“Fight or flight”
Energetic action

3. Autonomic Division: Homeostasis
Figure 11-1

4. Autonomic Pathways Coordination of homeostatic responses Autonomic
Endocrine
Behavioral
Figure 11-2

5. Autonomic Control Centers
Hypothalamus
Water balance, temperature, and hunger
Pons
Respiration, cardiac, and urinary
Medulla
Respiration
Figure 11-3

6. Two Efferent Neurons in Series
Autonomic pathways
Figure 11-4
Divergence in autonomic pathways
1 preganglionic neuron entering a ganglion synapses with about 10 postganglionic neurons
Each postganglionic neuron may innervate a different target
So one preganglionic neuron can regulate a variety of targets

7. Antagonistic Control
Autonomic sympathetic and parasympathetic pathways
What’s the difference?
Anatomically--
Sympathetic pathways originate in the thoracic and lumbar spinal cord and sympathetic ganglia are found in 2 chains that run along either side of spinal cord
Sympathetic pathways have short preganglionic axons and long postganglionic axons
Parasympathetic originate in brainstem and sacral region of spinal cord
Parasympathetic ganglia lie close to the effector organs
So parasympathetic preganglionic neruons have long axons and postganglionic neurons have short ones
Major parasympathetic tract is the vagus nerve (75% of all fibers)
Figure 11-5

8. Sympathetic versus Parasympathetic
Figure 11-7

9. Sympathetic versus Parasympathetic

10. Autonomic Targets Smooth muscle Cardiac muscle Exocrine glands
Endocrine glands
Lymphoid tissue
Adipose tissue

11. Autonomic Neuron Structure
Varicosities in autonomic neurons
Figure 11-8

12. Synapses in Autonomic Neurons
Neurotransmitter released to ECF
No synaptic cleft
Impact
Large area
Slow acting
Long duration
Norepinephrine activates 2 subtypes of  and  adrenergic receptors
G-protein coupled receptors that use different 2nd messengers
 receptors increase cAMP 1 receptors enhance cardiac muscle contraction 2 receptors relax smooth muscle
 receptors activate phospholipase C creating IP3 (release of calcium from intracellular stores) and DAG (phosphorylation)
1 receptors cause smooth muscle contraction or exocytosis
Acetylcholine activates G-protein coupled muscarinic receptors
2nd messenger cascades leading to opening of K+ or Ca2+ channels

13. Agonists and Antagonists

14. Adrenal Medulla Primary neurotransmitter Multiple and distant targets
Epinephrine
Multiple and distant targets

15. Adrenal Medulla
Figure 11-10b

16. Adrenal Medulla
Figure 11-10c

17. Review of Efferent Pathways
Somatic motor
pathway
CNS
Ach = acetylcholine
E = epinephrine
NE = norepinephrine
KEY
Skeletal
muscle
Nicotinic receptor
ACh
Figure (1 of 5)

18. Review of Efferent Pathways
ACh
Somatic motor
pathway
Parasympathetic
Ganglion
Nicotinic
receptor
CNS
AUTONOMIC PATHWAYS
Ach = acetylcholine
E = epinephrine
NE = norepinephrine
Autonomic effectors:
• Smooth and cardiac muscles
• Some endocrine and exocrine
glands
• Some adipose tissue
KEY
Skeletal
muscle
Muscarinic
Nicotinic receptor
Figure (2 of 5)

19. Review of Efferent Pathways
AUTONOMIC PATHWAYS
Somatic motor
pathway
Parasympathetic
pathway
Sympathetic
pathways
CNS
CNS
CNS
ACh
KEY
Nicotinic
receptor
Ach = acetylcholine
E = epinephrine
NE = norepinephrine
Ganglia
ACh
Nicotinic
receptor
Ganglion NE
ACh
a receptor
Muscarinic
receptor
Autonomic effectors:
• Smooth and cardiac muscles
• Some endocrine and exocrine
glands
• Some adipose tissue
ACh
Nicotinic receptor
Skeletal
muscle
Figure (3 of 5)

20. Review of Efferent Pathways
ACh
Somatic motor
pathway
Parasympathetic
Ganglion
Nicotinic
receptor
CNS
AUTONOMIC PATHWAYS
Sympathetic
pathways
Ganglia
Ach = acetylcholine
E = epinephrine
NE = norepinephrine
b1 receptor
Autonomic effectors:
• Smooth and cardiac muscles
• Some endocrine and exocrine
glands
• Some adipose tissue
KEY
a receptor
Skeletal
muscle
Muscarinic
Nicotinic receptor NE
Figure (4 of 5)

21. Review of Efferent Pathways
ACh
Somatic motor
pathway
Parasympathetic
Ganglion
Nicotinic
receptor
CNS
AUTONOMIC PATHWAYS
Adrenal
medulla
cortex E
Sympathetic
pathways
Ganglia
Ach = acetylcholine
E = epinephrine
NE = norepinephrine
b1 receptor b2
Blood
vessel
Autonomic effectors:
• Smooth and cardiac muscles
• Some endocrine and exocrine
glands
• Some adipose tissue
KEY
a receptor
Skeletal
muscle
Muscarinic
Nicotinic receptor NE
sympathetic pathway
Figure (5 of 5)

22. Neural Reflexes

23. Somatic Motor Reflexes
Monosynaptic and polysynaptic somatic motor reflexes
Figure 13-1a

24. Somatic Motor Reflexes
Figure 13-1b

25. Skeletal Muscle Reflexes
Proprioceptors are located in skeletal muscle, joint capsules, and ligaments
Proprioceptors carry input sensory neurons to CNS
CNS integrates input signal
Somatic motor neurons carry output signal
Alpha motor neurons
Effectors are contractile skeletal muscle fibers

26. Proprioceptors
Muscle spindles and Golgi tendon organs are sensory receptors in muscle
Figure 13-3a–b

27. Muscle Spindles
Muscle spindles monitor muscle length and prevent overstretching
Sensory
neuron
endings
Intrafusal
fibers of
muscle spindle
(a)
Extrafusal muscle
fibers at resting length
Sensory neuron is
tonically active.
Spinal cord integrates
function.
Alpha motor neurons
to extrafusal fibers
receive tonic input
from muscle spindles.
Extrafusal fibers maintain a certain
level of tension
even at rest.
Spinal
cord
Alpha motor 1 2 4 5 3
Figure 13-4a

28. Muscle Spindles
Muscle spindles monitor muscle length and prevent overstretching
Sensory
neuron
endings
Intrafusal
fibers of
muscle spindle
(a)
Extrafusal muscle
fibers at resting length
Spinal
cord 1
Figure 13-4a, step 1

29. Muscle Spindles Figure 13-4a, steps 1–2 (a) Extrafusal muscle
Sensory
neuron
endings
Intrafusal
fibers of
muscle spindle
(a)
Extrafusal muscle
fibers at resting length
Sensory neuron is
tonically active.
Spinal
cord 1 2
Figure 13-4a, steps 1–2

30. Muscle Spindles Figure 13-4a, steps 1–3 (a) Extrafusal muscle
Sensory
neuron
endings
Intrafusal
fibers of
muscle spindle
(a)
Extrafusal muscle
fibers at resting length
Sensory neuron is
tonically active.
Spinal cord integrates
function.
Spinal
cord 1 2 3
Figure 13-4a, steps 1–3

31. Muscle Spindles Figure 13-4a, steps 1–4 (a) Extrafusal muscle
Sensory
neuron
endings
Intrafusal
fibers of
muscle spindle
(a)
Extrafusal muscle
fibers at resting length
Sensory neuron is
tonically active.
Spinal cord integrates
function.
Alpha motor neurons
to extrafusal fibers
receive tonic input
from muscle spindles.
Spinal
cord
Alpha motor 1 2 4 3
Figure 13-4a, steps 1–4

32. Muscle Spindles Figure 13-4a, steps 1–5 (a) Extrafusal muscle
Sensory
neuron
endings
Intrafusal
fibers of
muscle spindle
(a)
Extrafusal muscle
fibers at resting length
Sensory neuron is
tonically active.
Spinal cord integrates
function.
Alpha motor neurons
to extrafusal fibers
receive tonic input
from muscle spindles.
Extrafusal fibers maintain a certain
level of tension
even at rest.
Spinal
cord
Alpha motor 1 2 4 5 3
Figure 13-4a, steps 1–5

33. Muscle Spindles
Figure 13-4b

34. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
Figure 13-7 (1 of 7)

35. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
Receptor: Muscle
spindle stretches
and fires.
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
Figure 13-7 (2 of 7)

36. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
Receptor: Muscle
spindle stretches
and fires.
Afferent path: Action
potential travels through
sensory neuron.
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
Figure 13-7 (3 of 7)

37. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
Receptor: Muscle
spindle stretches
and fires.
Afferent path: Action
potential travels through
sensory neuron.
Integrating
center:
Sensory neuron
synapses in
spinal cord.
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
Figure 13-7 (4 of 7)

38. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
Receptor: Muscle
spindle stretches
and fires.
Afferent path: Action
potential travels through
sensory neuron.
Integrating
center:
Sensory neuron
synapses in
spinal cord.
Efferent path 2: Interneuron
inhibiting somatic motor neuron
Efferent path 1:
Somatic motor neuron
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
onto
Figure 13-7 (5 of 7)

39. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
Receptor: Muscle
spindle stretches
and fires.
Afferent path: Action
potential travels through
sensory neuron.
Integrating
center:
Sensory neuron
synapses in
spinal cord.
Efferent path 2: Interneuron
inhibiting somatic motor neuron
Effector 2: Hamstring
muscle
Efferent path 1:
Somatic motor neuron
Effector 1: Quadriceps
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
onto
Figure 13-7 (6 of 7)

40. Patellar Tendon (Knee Jerk) Reflex
Stimulus:
Tap to tendon
stretches
muscle.
Receptor: Muscle
spindle stretches
and fires.
Afferent path: Action
potential travels through
sensory neuron.
Integrating
center:
Sensory neuron
synapses in
spinal cord.
Efferent path 2: Interneuron
inhibiting somatic motor neuron
Effector 2: Hamstring
muscle
Response: Hamstring
stays relaxed, allowing
extension of leg
(reciprocal inhibition).
Efferent path 1:
Somatic motor neuron
Effector 1: Quadriceps
Response: Quadriceps
contracts, swinging lower
leg forward.
The patellar tendon (knee jerk)
reflex illustrates a
monosynaptic stretch
reflex and reciprocal
inhibition of the
antagonistic muscle.
onto
Figure 13-7 (7 of 7)

41. Movement