Download The NERVOUS System

Unit II. Nervous and Endocrine
Part 2: The Nervous System
The
NERVOUS
System
A. Functions of the Nervous
System
1. Monitors stimuli (Sensory input)
2. Processes, makes decisions about how to
respond to stimuli.
3. Causes a response by activating muscles,
or glands (motor output)
B. Divisions of the Nervous
System
• Central Nervous System (CNS)
- brain and spinal cord
-interprets sensory info and
decides on response based on past
experience, reflexes, and current
conditions.
• Peripheral Nervous System (PNS):
-nerves extending
from the CNS
-these nerves link all of the parts of
the nervous system
CNS
C. Reflex Arch
• Skips the brain, goes straight to spinal cord to
react
D. Divisions of the PNS
• Somatic Nervous System
-Offers voluntary control over
skeletal muscles.
• Autonomic Nervous System
-regulates the activity of cardiac
and smooth muscles.
-regulates hormonal activity
Autonomic
E. Characteristics of Nerves
• Nerves (Neurons)
• amitotic: they do not divide (cannot be
replaced if destroyed)
-high metabolic rate-require constant O2
and glucose, die within a few minutes
without O2
Dentrite – toward cell body
Cell body- located in brain or spinal cord
Axon – Away- extends to other organs (muscles or
glands).
Myelin Sheath - increases the speed of nerve
impulses.
Nodes of Raniver – where signals transmitted.
F. How Neurons Act
1. Neuron AT REST
• Resting Potential: the inside of the cell
membrane is more negatively charged
than the outside.
At rest, there is more Na+ outside than
inside the cell. (More K+ is inside the cell)
2. Sodium Potassium Pump!
• Sodium and Potassium: Na+ and K+
are exchanged across the cell membrane
to signal action.
• ATP is needed!!
• Like the wave
3. The role of Calcium
• Calcium is needed to open the
Neurotransmitter channels in our axon
terminal.
• Neurons communicate at synapses - gap
G. Diseases
• Multiple Sclerosis – Myelin Sheaths are
gradually degenerate.
• ALS
• Congenital Insensitivity to Pain
Drugs can affect your nervous
system.
• Article