1. Efferent Division: Autonomic and Somatic Motor Control
Chapter 11
Efferent Division: Autonomic and Somatic Motor Control

2. About this Chapter Efferent division and what it controls
Pathways receptors and neurotransmitters
Antagonistic controls: sympathetic and parasympathetic
Control of cardiac, smooth muscle, some adipose tissue and glands in homeostasis
CNS control of skeletal muscles through neuromuscular junctions

3. Autonomic Division: Homeostatic balancing
Controls
Smooth & cardiac muscle
Glands & adipose
Antagonistic branches
Parasympathetic
"Rest & digest"
Restore body
Sympathetic
"Fight or flight"
Energetic action

4. Autonomic Division: Homeostatic balancing
Figure 11-1: Homeostasis and the autonomic division

5. Autonomic Control Centers
Hypothalamus
Water balance
Temperature
Hunger
Pons
Respiration
Cardiac
Vasoconstriction
Medulla
Figure 11-3: Autonomic control centers in the brain

6. Autonomic Pathways: Communicate to Body
Coordinates homeostatic responses
Autonomic
Endocrine
Behavioral
Blood pressure
Osmolarity
Tonic regulation
Antagonistic control
Receptor directed response

7. WHAT IS ROHHAD?
ROHHAD is an acronym for rapid-onset obesity with hypothalamic dysregulation, hypoventilation and autonomic dysregulation.
It affects the part of the nervous system that controls involuntary actions and the endocrine system.
Scientists suspect the condition is genetic but are still unsure.
The disease is incredibly rare, and less than 100 people in the world have been diagnosed with it. 
Signs and symptoms:
Dramatic weight gain over a six to 12-month period
Inability to maintain normal water balance in the body
Inability to regulate body temperature
Slow heartbeat and excessive sweating
Very shallow breathing during sleep
There is currently no cure for ROHHAD, with the average life expectancy being between five and nine, reports suggest.
Because it can affect many different parts of the body, children are often cared for by a team of healthcare providers from various fields.
The weight gain is often hard to control through exercise and diet - but keeping active helps to avoid excess from being piled on.

8. Autonomic Pathways: Communicate to Body
Figure 11-2: The hypothalamus and brain stem initiate autonomic, endocrine, and behavioral responses

9. Autonomic Pathways: Two Efferent Neurons
CNS
Preganglionic neuron
Ganglion
Postganglionic neuron
Target tissue
Figure 11-4: Autonomic pathways

10. Comparison of sympathetic and Parasympathetic Pathways
Neurotransmitters
Receptors
Figure 11-7: Sympathetic and parasympathetic pathways

11. Parasympathetic Branch: “Rest and Digest”
Preganglionic neurons
Originate in
Brain stem
Lower cord
NT: cholinergic
Ganglion
Near target
Nicotinic receptors
Postganglionic neuron

12. Figure 11-5: Autonomic sympathetic and parasympathetic pathways

14. Actions of Parasympathetic Branch
Constricts
Pupil
Bronchioles
Slows heart
Stimulates
Digestion
Insulin release
Urination
Erections

15. Sympathetic Branch: “Fight or Flight”
Preganglionic neuron
Short
Origin: spinal cord
NT: cholinergic
Ganglia
Sympathetic chain
Near spinal cord
Postganglionic neuron
Long
NT: adrenergic

16. Homeostasis Hypothalamus: Homeostatic Functions Hunger, stress
Thirst: body osmolarity
Flight/fight pathways
Anger & fear
Circadian rhythms
Coordinates with endocrine system

17. Additonal Functions of Hypothalamus
heart rate
urinary bladder contraction
blood pressure
oxytocin release
vasopressin release
corticotropin-releasing hormone release[8]
thermoregulation
panting
sweating
thyrotropin inhibition
GI stimulation
satiety
neuroendocrine control
Gonadotropin-releasing hormone (GNRH), also known as Luteinizing-hormone-releasing hormone(LHRH)
pupillary dilation
shivering

18. Examples of Autonomic Reflexes
Cold Water (Whole Body) Immersion causes tachycardia
Exposure of face to cold water causes bradycardia: Mammalian Diving Reflex via Vagal Nerve
Pupillary Reflex-Pupil Constricting in response to light
Baroreceptor Reflex- Low BP in carotid sinus results in tachycardia and blood vessel constriction
Carotid Sinus Reflex- Increased pressure within or external manipulation of carotid sinus results in bradycardia
Dilation of Blood vessels as body temperature increases
Secretion of epinephrine and norepinephrine from the adrenal medulla in response to fear or stress
Sweating in response to increased body temperature

19. Autonomic Effects on Cardiovascular System
Target
Sympathetic (adrenergic)
Parasympathetic (muscarinic)
cardiac output
β1, (β2): increases
M2: decreases
SA node: heart rate (chronotropic)
β1, (β2) [4]: increases
Atrial cardiac muscle: contractility (inotropic)
β1, (β2)[4]: increases
at AV node
β1: increases conduction increases cardiac muscle automaticity [4]
M2: decreases conduction Atrioventricular block [4]
Ventricular cardiac muscle
β1, (β2): increases contractility (inotropic) increases cardiac muscle automaticity [4]
---
Heart

20. Autonomic Effects on Blood Vessels
Target
Sympathetic (adrenergic)
Parasympathetic (muscarinic)
vascular smooth muscle in general
α1:[5] contracts; β2:[5] relaxes
M3: relaxes [4]
renal artery
α1[6]: constricts
---
larger coronary arteries
α1 and α2[7]: constricts [4]
smaller coronary arteries
β2:dilates [8]
arteries to viscera
α: constricts
arteries to skin
arteries to brain
α1[9]: constricts [4]
arteries to erectile tissue
α1[10]: constricts
M3: dilates
arteries to salivary glands
hepatic artery
β2: dilates
arteries to skeletal muscle
Veins
α1 and α2 [11] : constricts β2: dilates
Blood vessels

21. Stimulatory Actions of Sympathetic Branch
Pupil dilation
Salivation
Heart beat & volume
Dilation
Blood vessels
Bronchioles
Catecholamine release
Fat breakdown
Ejaculation

22. Inhibitory Actions of Sympathetic Branch
Digestion
Pancreas secretion
Urination

23. Adrenal Medulla: A Modified Sympathetic Ganglion
Sympathetic stimulation
Catecholamine release to blood
Epinephrine
Norepinephrine
Travel to:
Multiple targets
Distant targets

24. Adrenal Medulla: A Modified Sympathetic Ganglion
Figure 11-10: The adrenal medulla

25. Synapses in Autonomic Nerves
Varicosities
NT released to ECF
No cleft
Impact
Large area
Slow acting
Long duration
Figure 11-8: Varicosities of autonomic neurons

26. Mechanism: Norepinephrine Release and Recycling
Figure 11-9: Norepinephrine release at a varicosity of a sympathetic neuron

27. Review of Efferent Pathways: Motor & Autonomic
Figure 11-11: Summary of efferent pathways

28. Somatic Motor Division: Controls Skeletal Muscles
Body movement
Appendages
Locomotion
Single neuron
CNS origin
Myelinated
Terminus
Branches
Neuromuscular junction
Figure 11-11: Summary of efferent pathways

29. Neuronmuscular Junction: Overview
Terminal boutons
Synaptic cleft
Filled with a fibrous Matrix (collagen)
AChE
Hold axon terminal and motor end plate together
Motor end plate
On muscle
Nicotinic receptors

30. Neuronmuscular Junction: Overview
Figure 11-12: Anatomy of the neuromuscular junction

31. Neuronmuscular Junction: Mechanism of Signal Conduction
Axon terminal
AP signals
ACh release
Motor end plate
2 ACh bind
opens cation channel
Na+ influx
Membrane depolarized
Stimulates fiber contraction

32. Neuronmuscular Junction: Mechanism of Signal Conduction
Figure 11-13: Events at the neuromuscular junction

33. Summary Autonomic branches: sympathetic and parasympathetic
Regulate glands, smooth & cardiac muscles
Team with endocrine to regulate homeostasis
Are regulated by hypothalamus, pons & medulla
Have pathways with 2 neurons and a ganglion
Use varicosities to release NTs
Have diverse receptors: tonic & antagonistic regulation

34. Summary Efferent motor neurons control skeletal muscles
Single long myelinated neuron from CNS
Neuromuscular junction structure & mechanism