1. Prayer
Attendance
Homework

2. Peripheral Nervous System (PNS)
21 pairs of cranial nerves
31 pairs of spinal nerves
Innervates (신경을 분포시키다) upper body
and head
Innervates entire body

3. Peripheral Nervous System (PNS)
Motor Division
(efferent)
From CNS to Effectors
Sensory Division
(afferent)
From Sensory Receptors to CNS
Somatic Nervous System
Autonomic Nervous System
Sympathetic Division
Parasympathetic Division

4. Questions 9

5. Motor Division (SNS)
The somatic nervous system (SNS) moves muscles when there is external stimuli.
Somatic pathways:
Most are under voluntary control (자발적 통제)
Some are involuntary (무의식적) monosynaptic or polysynaptic reflexes.
Very simple somatic pathway:
Has one sensory neuron and one motor neuron

6. Monosynaptic Reflexes
Has only 1 synapse between the sensory neuron and the motor neuron.
The pathway, or reflex arc, travels from the sensory receptor to the sensory neuron, which synapses directly with the motor neuron in the spinal cord.
The reflex arc is involuntary and occurs in the spinal cord.
Example: Reflex Arc for Knee-Jerk

7. Example: Reflex Arc for Knee-Jerk
The tendon covering the patella (knee) is hit.
Stretch receptors fire.
An action potential is sent along the sensory neuron and into the spinal cord.
The sensory neuron synapses with a motor neuron in the spinal cord.
This simulates the quadriceps muscle to contract.
The knee jerks forward.

8. Polysynaptic Reflexes
The sensory neurons synapse with one or more interneurons.
The withdrawal reflex is an example of a postsynaptic reflex.
When a person steps on a nail, the injured leg withdraws in pain, while the opposite leg extends to offer support.

9. Questions 10

10. Motor Division (ANS)
The autonomic nervous system (ANS) regulates the internal environment using involuntary actions and processes.
ANS motor neurons innervate:
Most ANS pathways have 2 motor neurons.
One motor neuron has its cell body within the CNS, then synapses outside the CNS with another motor neuron, which innervates the effector.
Two divisions: sympathetic and parasympathetic
Heart
Smooth muscle in blood vessels
Digestive tract
Endocrine system
Excretory system
Respiratory system
Reproductive system

11. Sympathetic Division Responsible for fight or flight responses
Sympathetic neurons start in the thoracic and lumbar parts of the spinal cord.
The presynaptic axon is short
The postsynaptic axon is long.
The presynaptic membrane secretes acetylcholine
The postsynaptic membrane (effector) secretes norepinephrine (adrenaline).
Increased heart rate
vasoconstriction of blood vessels in the skin
Inhibition of digestion
vasodilation of blood vessels in skeletal muscle
Dilation of pupils
학생들 의 팽창
piloerection 경직

12. The Parasympathetic Division
Innervates actions that conserve energy and restore the body to normal activity following exertion (rest and digest)
Parasympathetic neurons stimulate:
Vagus nerve is one of the most important parasympathetic nerves.
Parasympathetic neurons start in the cranial and sacral parts of the spinal cord.
The presynaptic axon is long
The postsynaptic axon is short.
The neurotransmitter secreted in both the presynaptic synapse and the postsynaptic synapse is acetylcholine.
Decrease in heart rate.
Increase in digestive action.
Vasodilation of blood vessels in the skin

13. Questions 11