Transcript Central Nervous System (CNS)

Nervous System: Part 2
Organization of the Nervous System
The Senses
Nervous System Organization
Central Nervous System (CNS)
brain
spinal cord
Peripheral Nervous System (PNS)
Sensory nerves
Motor nerves
carry sensory information
into brain and spinal cord
carry motor information
from CNS to effectors
somatic sensory
nerves: signals
from skin,
muscles,
joints, special
senses
visceral sensory
nerves:
signals from
body organs
Somatic motor
nerves: signals
to skeletal
muscles,
voluntary
Sympathetic
division
“fight or flight”
Autonomic
motor nerves:
signals to smooth
muscle, cardiac
muscle, glands,
involuntary
Parasympathetic
division
“rest and digest”
Parts of the Brain
Cortex: thinking,
learning, memory,
speech movement,
senses
sends
sensory input
to cerebrum
homeostasis
muscle
coordination
breathing, heart rate,
blood pressure
Spinal Cord
and Reflex Arcs
pin
dorsal root ganglion
Involve the
Somatic
Nervous
System
central canal
white matter
sensory
receptor
(in skin)
Dorsal
gray matter
dorsal
horn
cell body of sensory neuron
axon of sensory neuron
cell body of interneuron
effector
(muscle)
axon of motor neuron
ventral root
cell body of
motor neuron
Ventral
ventral horn
Autonomic Nervous System
dilates pupils
speeds heart
dilates air
passages
decreases
stomach and
intestinal activity
constricts
pupils
slows heart
constricts
bronchioles
increases
stomach and
intestinal activity
Nervous System Case Study:
Hemimegalenchephaly
• Dylan Catania was born with an oversized right
hemisphere in his brain that was causing constant
seizures
• His only hope of survival and brain development
involved early surgery to sever the connections
between the right and left hemispheres of the brain
Nervous System Case Study:
Hemimegalenchephaly
Nervous System Case Study:
Surgery for Hemimegalenchephaly
Nervous System Case Study:
Surgery for Hemimegalenchephaly
Nervous System Case Study:
Hemimegalenchephaly
Dylan has been seizure free
since his surgery!
Sensation and Perception
Sensation:
impulses arrive
at cerebral
cortex
Perception:
cortex interprets
meaning of
sensations
Sensory Areas on Cerebral Cortex
Sense of Vision: Structure of the Eye
photoreceptors
detect light
takes nerve
impulses to
brain
Photoreceptors
synapse with
neurons that
take signal to
optic nerve
lens
focuses
light on
retina
photoreceptors
Sense of Vision: Photoreceptors
detects color
detects light
absorbs light,
initiates series
of steps leading
to nerve signal
Sense of Hearing:
Structure of the Ear
3. Ossicles (bones) of
middle ear multiply
pressure of vibration
4. Membrane-covered
opening transfers
pressure to inner ear
1. Sound enters
auditory canal
2. Eardrum vibrates
slightly due to
sound waves
5. Pressure enters
fluid-filled chamber
containing
mechanoreceptors
Sense of Hearing: Mechanoreceptors
Bend when basilar
membrane moves
mechanoreceptor
Vibrates in
response to
pressure in
inner ear
takes nerve
impulses to
brain
Sense of Taste:
Chemoreceptors
Taste buds
occur along
the walls of
papillae
Molecules bind
to receptors on
microvilli of
taste cells
Signal from
receptor is
transmitted
within the cell
Nerve
impulses are
sent to brain
chemoreceptor
Sense of Taste
Signal Transmission for Salty and Sour Tastes
Sodium binds and
opens a channel
for more sodium
to enter
Protons bind and
open a channel
for more protons
to enter
Release of calcium
triggers
neurotransmitter
release and neuron
stimulation
Sense of Taste
Signal Transmission for Sweet and Bitter Tastes
Internal
communication
leads to neuron
stimulation