Transcript Chapter 14 - The Nervous System: Organization

Chapter 15/16 - The Nervous
System: Organization
Divisions of the Vertebrate
Nervous System
• The central nervous system (CNS) is the
brain and spinal cord.
• The peripheral nervous system (PNS) is
the nerves and ganglia. (Ganglia are
clusters of nerve cell bodies outside the
CNS.)
CONT’D
Somatic Nervous System
• The somatic nervous system provides
conscious, voluntary control.
• It includes all of the nerves that serve the
skeletal muscles and the exterior sense
organs.
Reflex Arc
http://www.brainviews.com/abFiles/AniPatellar.htm
Autonomic Nervous System
CLASSES OF NEURONS
• Sensory neurons (afferent neurons) conduct
sensory information toward the CNS. Sensory
neurons have a long dendrite and a short axon.
• The brain and spinal cord contain interneurons.
These receive information and if they are
sufficiently stimulated, they stimulate other
neurons.
• Motor neurons (efferent neurons) send
information from interneurons to muscle or gland
cells (effectors).
Neurons
STRUCTURE
• Cell Body- contains nucleus and
organelles
• Dendrites- receive input
• Axon -conducts impulses away from the
cell body
• Axon Terminals - Neurotransmitters are
manufactured in the cell body but released
from axon terminals. The
neurotransmitters stimulate other neurons.
CONT’D
Nerves and Ganglia
• Axons and dendrites are bundled with
axons or dendrites from other neurons to
form nerves.
• Clusters of neuron cell bodies are called
ganglia.
SODIUM POTASSIUM PUMP
NEURON MEMBRANE
ACTION POTENTIAL
ACTION POTENTIAL
Excitatory and inhibitory
postsynaptic potentials
• A synaptic potential can be excitatory (they
depolarize) or inhibitory (they polarize). Some
neurotransmitters depolarize and others
polarize.
• There are more than 50 different
neurotransmitters.
• In the brain and spinal cord, hundreds of
excitatory potentials may be needed before a
postsynaptic cell responds with an action
potential.
http://www.blackwellpublishing.com/matthews/neurotrans.htm
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Synaptic integration
Temporal and Spatial Summation
• The effect of more than one synaptic
potential arriving at a neuron is additive if
the time span between the stimuli is short.
This is called temporal summation.
• The effect of more than one synaptic
potential arriving at a given region of a
neuron can also be additive. This is called
spatial summation.
Synaptic Transmission
Central Nervous System
• The central nervous system is the brain
and spinal cord.
• It is wrapped in 3 layers of membranes
called meninges. Meningitis is an
infection of these coverings.
• The brain contains fluid-filled ventricles
that are continuous with the central canal
of the cord.
The Spinal Cord
The Brain …Hopefully not yours
http://outreach.mcb.harvard.edu/animations/brainanatomy.swf
Regions of Disease and Disorders
Lobes of the cerebral cortex
Summary
Lobe
Function
Frontal
motor functions; permits conscious control of skeletal muscles; contains
the primary motor cortex
conscious thought
Parietal
sensory areas from the skin; contains the primary sensory cortex
Occipital
The primary visual cortex is located within the occipital lobe.
Temporal
hearing and smell
Parts of the Brain
Summary of Brain Structure
Brain Structure Function
Medulla
oblongata
Vital functions such as breathing, heart rate, and blood pressure
Reflexes such as vomiting, coughing, sneezing, hiccupping,
swallowing, and digestion
Neurons cross
Pons
Breathing, connects spinal cord, cerebellum and higher brain centers
Cerebellum
Motor coordination
Midbrain
Receives visual, auditory, and tactile information
In mammals, this information is sent to the thalamus and higher
brain centers. In lower vertebrates, the information is further
processed in the midbrain.
Thalamus
Relays sensory information to the cerebral cortex.
Contains part of the reticular formation (controls arousal).
Hypothalamus
Maintains homeostasis, regulates the endocrine system
Contains part of the Limbic system (controls emotion)
Cerebrum
Processes sensory information and produces signals that
move the skeletal muscles.
Cerebral
Cortex
This is the outer layer of the cerebrum.
Thinking, intelligence, and cognitive functions are located
here.
Processing of sensory information and motor responses