Transcript Nervous System Ch 35

The Nervous System
Nervous System Function
 Receives & relays
information about
activities within the body
 Monitors & responds to
internal and external
changes
Nerve/Brain Facts
 The brain is made up of
approx. 100 billion neurons
 WE DO NOT USE ONLY
10% OF OUR BRAINS
 we use 100% of
our brain
Nerve/Brain Facts (cont.)
 Your brain weighs
approx. 3 lbs
 Your spinal cord is
approx. 43-45 cm
long
 Nerve Impulses travel
395 feet
Bundles of nerve fibers
What are neurons?
 Nerve cells that
carry messages
throughout the
nervous system
Anatomy of a Neuron
 Dendrites:
receive
messages &
brings them
to cell body
Anatomy of a Neuron (cont.)
 Axon:
transmits
messages, AKA
nerve impulses,
away from cell
body
Anatomy of a Neuron (cont.)
 Myelin Sheath:
membrane
surrounding
axon
• faster nerve
conduction
Anatomy of a Neuron (cont.)
 Cell Body:
contains
organelles
•mitochondria,
nucleus, etc.
Types of Neurons
1. Sensory neurons
2. Motor neurons
3. Interneurons
1. Sensory Neurons
 Carry impulses to the
central nervous system
(CNS)
 EX. From sense organ to
brain and spinal cord
2. Motor Neurons
 Carry impulses
from the brain
and spinal cord
to muscles or
glands
3. Interneurons
 Receives impulse from
sensory neurons &
carries impulse to motor
neurons
Interneuron
How Neurons Work
 Neurotransmitters:
chemicals that
carry nerve
impulses /
messages between
gaps or synapse
between neurons
Action Potentials
 Sodium ions rush into
cell & Potassium ions
rush out
 Sodium-potassium pump
restores balance
Transmission of Nerve
Impulses
 Nerve impulses begin
when ion concentrations
change
• Sodium & Potassium
 Caused by a series of
action potentials
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html
Nervous System
Organization
 Peripheral Nervous
System (PNS)
• Autonomic & Somatic
Nervous Systems
Autonomic
Nervous System
 Controls smooth
muscle, organs &
glands
• Further broken
down into
parasympathetic
& sympathetic
Somatic Nervous System
 Controls voluntary
muscle contractions
•Under conscious
control
The Central Nervous
System
Basic Info
 2 Parts: Brain & Spinal
 Cord
• Covered by meniges
 Processes & sorts info.
 Controls behavior
 Sends messages throughout
body
CNS continued:
 Brain has 4 main parts:
•Cerebrum
•Cerebellum
•Brain stem
•Hypothalmus
Brain Anatomy
 2 Hemispheres
 Surface covered with:
•gyri (bumps) & sulci
(creases)
Increase
surface area
Cerebrum
AKA Cerebral Cortex
•Control center
•Controls:
• Memory
• Awareness
• Thought
• Language
• Reasoning
• Perception
• Voluntary
movement
Cerebrum:
 Cerebrum named by
region:
•Frontal Lobe –
judgment, impulses
•Parietal Lobe –
understand & process
information
Cerebrum continued:
•Occipatal Lobe –
visually process
•Temporal Lobe –
controls hearing &
recognition
Named by
bones that
cover them!
Cerebellum
 Important for coordination
of movement
 Responsible for body
movements, posture,
muscle tone, equilibrium
Brain Stem
 Connects the brain to the
spinal cord
 Controls vital life processes
•breathing, swallowing,
digestion, heart rate &
blood pressure
Diencephalon Region
“interbrain”
Consists of the thalamus,
subthalamus, hypothalamus,
epithalamus
Body’s center for
emotions & instincts
• Body Temp
Controls
• Thirst
• Hunger
• Hostility
• Pain
• Sexual Desire
Hypothalmus:
 Emotions & instincts
 Controls body
temperature,
thirst, hunger,
hostility, & pain
Problems due to
Neurotransmitters
•Parkinson's Disease: dopamine
producing neurons destroyed
(lack of movement)
•Depression: deficit in serotonin
&/or dopamine
•Schizophrenia: high level of
dopamine
Epilepsy
•Seizures due to large
numbers of impulses sent
simultaneously
•Affects 1 out of every 200
people in U.S. & 50
million people worldwide
Multiple Sclerosis
 Body attacks myelin
sheath
 Causes nerve
impulses to
short circuit
Studying The Brain
 CAT Scan: used
to locate tumors,
damaged regions
& blood clots
 AKA CT Scan –
computed axial
tomography
Studying The Brain (cont.)
 PET Scan:
used to look at
brain activity
Positron
emissions
tomography
Studying The Brain (cont.)
 MRI: used to
look at brain
tissue
MRI of an
individual
with MS
Magnetic resonance
imaging