Transcript The Nervous System & the control of movement

The Nervous System
& the control of movement
Chapter 6
Q: What is the main role of
the Nervous System?
A: To “assemble info about conditions
external & internal to the body, to
analyze this information and initiate
an appropriate response”.
“COMMUNICATION NETWORK”
The Nervous System
The Nervous System
The body's "Communication System"
The Central Nervous System
(CNS)
Brain
1. cerebrum
2. cerebellum
3. brain stem 4. diencephalon
5.limbic system 6.reticular activating system
The Peripheral Nervous System
(PNS)
Spinal Cord
12 Cranial Nerves
31 pairs of Spinal Nerves
Autonomic Nervous System
(involuntary)
Sympathetic
"Fight or Flight"
Parasympathetic
"Homeostasis"
Somatic Nervous System
(voluntary)
What are the 2 Major
Components of the
Nervous System?
1. The Central Nervous System
2. The Peripheral Nervous System
CNS (Central Nervous System)
 Two Parts:
A) The Brain
B) The Spinal Cord (& vertebral column)
CNS ‘A’ - The Brain
 Main control center for survival
 Emotions
 The brain is made up of 6 parts:
The 6 Brain Segments
1) Cerebrum:
-largest section
-controls sensory, motor & intelligence
functions
-2 hemispheres / 8 ‘lobes’
The 6 Brain Segments
(continued)
2) Cerebellum - coordinates balance
& muscle movement
3) Brain Stem - links cerebrum to the
spinal cord
---> Autonomic functions like
“muscle tone”
The 6 Brain Segments
(continued)
4. Diencephalon
-divided into the:
i) Thalemus
-pain & attention
ii) Hypothalemus
-appetite
-emotions
-body temperature
The 6 Brain Segments
(continued)
5. Limbic System:
-regulates basic drives like hunger,
emotions, aggression
6. Reticular Activating System
-crucial for maintaining consciousness
CNS ‘B’ - Spinal Cord
(& Vertebral Column)
 Main info pathway between brain &
PNS
 Spinal Cord - 45cm (brain stem to
L2)
 Spinal Nerves carry:
-sensory info to CNS &
-motor commands away from CNS
What are the 2 Major
Components of the
Nervous System?
1. The Central Nervous System
2. The Peripheral Nervous System
PNS (Peripheral Nervous System)
 12 Cranial Nerves / 31 Spinal Nerves
(sensory fibers)
 Responsible for voluntary actions & bodily
functions
 Eg heart beat, muscle control
 Made of Autonomic NS & Somatic NS
 Efferent nerves (motor) - carry info from
CNS to organs (Efferent-->muscles)
 Afferent nerves (sensory)- carry info to
brain --> Afferent-->brain)
PNS ‘A’- Autonomic
Nervous System
 Involuntary
i) Sympathetic System:
-prepares body for emergencies
(fight or flight response)
ii) Parasympathetic System:
-returns boy to normal after ‘emergency’
PNS ‘B’- Somatic Nervous
System
Components:
-afferent & efferent nerve fibers
-PNS controls and knows what our
muscles/tendons are doing & feeling
(ie pain, cold, balance, etc.)
REFLEX ARC
-Automatic response to stimulation
-if command center for the flex is:
a)the brain ---> cerebral reflex arc
b)the spinal cord --->spinal reflex arc
Autonomic Reflexes
-some involve smooth muscle, cardiac
muscle, glands
-regulates digestion, blood pressure,
sweating
Somatic Reflexes
-involve stimulation of skeletal muscle
ie -stretch reflex, withdrawl reflex
Basic Reflex Arc
 The components of a basic reflex
include;
i) receptor
ii) adjustor
iii) effector
Reflex Arc
The components of a reflex arc include;
i) receptor
ii) sensory or AFFERENT nerve (brain)
iii) intermediate nerve fibers (adjustor)
which interprets the signal & issues an
appropriate response
iii) motor or Efferent nerve (muscle)
v) effector organ (muscle)
-if command center for the flex is:
a)the brain ---> cerebral reflex arc
b)the spinal cord --->spinal reflex arc
Proprioceptors
Provide info re:
- muscle contraction
- position of limbs
- body posture
- balance
Proprioceptors
There are 2 receptors:
i)
Golgi Tendon Organs (GTO)
ii)
Muscle Spindles
Golgi Tendon Organs
- tension detectors
- In the tendon of the muscle
- Tension Reflex: GTO, Afferent
Neuron, CNS, Efferent Neuron, Motor
unit
Muscle Spindles
-senses changes in muscle length
-2 afferent neurons & 1 efferent
neuron
-very sensitive
“Stretch Reflex”
(see table 6.1 on pg. 101 in text)