1. Unit 5 Nervous System part 5: Autonomic Nervous System (ANS)

2. Autonomic Nervous System
Subdivison of the peripheral nervous system that regulates involuntary effectors (cardiac and smooth muscle, glands)
2 Divisions: Sympathetic and Parasympathetic
Act as antagonists

4. Functions of the ANS
Regulates autonomic effectors in ways that tend to restore homeostasis quickly
Principle of autonomic antagonism

5. Sympathetic Division
At rest, the sympathetic division will counteract the parasympathetic division to maintain normal body levels
The major function of the sympathetic division is to serve as an “emergency system” called the “fight-or-flight” response
When the body is under stress, or might be threatened, and homeostasis is threatened our outgoing sympathetic responses increase greatly to prepare our body to “fight” or “flee”

6. Epinephrine may cause the following responses:
Nerve fibers that play a role in the sympathetic response release the neurotransmitter epinephrine (more commonly know as adrenaline)
Epinephrine may cause the following responses:
Increased heart rate
Dilation of blood vessels in skeletal and cardiac muscles
Constriction of blood vessels in non-essential organs
Dilation of respiratory airways
Increased sweating
Increased blood glucose levels
Secretion of epinephrine and norepinephrine from adrenal glands

7. This is a normal reaction in times of stress, which enables us to retreat or resist a perceived threat
However, chronic exposure to such stress can lead to dysfunction of the ANS

9. Parasympathetic division
At rest, the parasympathetic division controls most effectors
After the fight-or-flight the “rest and repair” division dominates
Parasympathetic division slows heart rate, and promotes digestion using the neurotransmitter ACh
Has an excitatory effect on skeletal muscle, but an inhibitory effect on smooth and cardiac muscle

10. SLUD
S—salivation
L—lacrimation (all return to normal)
U—urination
D—defecation +
Heart rate returns to normal

11. Reflex Arcs Many nerve impulse pathways act as reflex arcs
Reflex- automatic subconscious response to changes (stimuli) within or outside the body
Help to maintain homeostasis by controlling involuntary processes like breathing, heart rate, blood pressure, etc.
Usually used to describe only involuntary responses (swallowing, coughing, vomiting)

12. There are 5 main components of a reflex arc:
1) Sensor/Receptor- receives a stimulus
2) Sensory Neuron- Sends the sensory info to the CNS to be integrated
3) Integration Center- Brain or spinal cord, interprets sensory info and sends an outgoing motor response
4) Motor Neuron- carries the motor response to an effector
5) Effector- Muscle or gland that responds

16. Today we will test your somatic reflexes because the somatic reflexes have an important clinical significance
Abnormalities may be present in certain diseases

17. Patellar Reflex- animation (first one)

18. Biceps Jerk- animation

19. Achilles Reflex (Ankle Jerk)- animation

20. Plantar Flexion- animation

21. Testing the Pupillary Reflex- animation (stop at 55sec)
CN: cranial nerve