Transcript Chapter 28- Nervous System

Chapter 28- Nervous System
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Acetylcholine
Action potential
Amygdale
Autonomic nervous system
Axon
Basal ganglia
Biogenic amines
Biological clock
Blood-brain barrier
Brain
Brainstem
Cell body
Central canal
Central nervous system (CNS)
Centralization
Cephalization
Cerebellum
Cerebral cortex
Cerebral hemispheres
Cerebrospinal fluid
Cerebrum
Corpus callosum
Cranial nerves
Dendrites
Effectors
Electroencephalogram (EEG)
Forebrain
Ganglia
Gray matter
Hindbrain
Hippocampus
Intergration
Interneurons
Lateralization
Limbic system
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Long-term depression (LTD)
Long-term memory
Long-term potentiation (LTP)
Medulla oblongata
Meninges
Midbrain
Motor division
Motor neurons
Motor output
Myelin sheath
Nerve
Nerve cords
Nerve net
Nervous system
Neurotransmitter
Nodes of Ranvier
Parasympathetic division
Peripheral nervous system (PNS)
Pons
Referred pain
REM sleep
Resting potential
Reticular formation
Sensory division
Sensory input
Sensory neurons
Short-term memory
Sodium potassium pumps
Somatic nervous system
Spinal cord
Spinal nerves
Stimulus
Summation
Supporting cells
Sympathetic division
Synaptic cleft
Synaptic knobs
Threshold potential
Ventricles
White matter
The nervous system
• Receives signals, interprets them and sends out
appropriate commands
• 2 divisions:
– Central- CNS- brain and spinal cord- where integration occurs
– Peripheral- PNS- nerves- carry signals in and out of CNS
The neuron
• Nerve cell- carries the signal
– 3 functions:
– Sensory input: signal from sense receptor to integration center
– Integration: interpretation of sensory signals and formation of
responses
– Motor output: conduction of signal from integration center to
effector- which performs body’s response
• Types of neurons– Sensory- convey info from sense receptor to CNS
– Interneuron- relays signal to other interneurons or motor
neurons
– Motor- CNS to effectors
Knee- jerk reflex
Parts of a neuron
• Cell body- holds nucleus and
organelles
• Dendrites- short branches off cell
body, receives messages
• Axon- longer, usually 1 fiber, sends
signal towards other neuron or
effector
• Supporting cells- protect, insulate
and reinforce neurons
• Myelin sheath- made of Schwann
cells- insulates
• Nodes of Ranvier- space between
Schwann cells, signal jumps from
node to node to move faster
• Nerve- cable-like bundle of neuron extensions wrapped
in CT
• Ganglia- clusters of neuron cell bodies in the nerves
Nerve signal
• Change in membrane potential
• Resting potential- voltage across the plasma membrane
– Diffusion of ions and Na/K pumps maintain resting
potential
Nerve signal con’t
• Stimulus- factor that causes a nerve cell to be generated
• Action potential- nerve signal- change in the membrane
voltage
– When stimulus is applied- threshold voltage is
reached
– Change in charge is caused by rapid movements of
Na and K at membrane channels
Nerve signal con’t
• Action potential propagates itself
– Electrical changes in 1 section trigger them
in another
– Frequency of action potentials changes
with intensity of stimulus
Synapse
• Space between 2 neurons or a neuron
and an effector cell
– Signal sent can be electrical or chemical
– Synaptic cleft- gap between neurons, prevents action potential
from sending info, action potentials can be converted to chemical
signals (neurotransmitters)
• The action potential triggers vesicles to fuse with plasma
membrane
• Neurotransmitters bind to receptors and open ion channels to
ions that start new action potential or stops one
• Neurotransmitter is then broken down or taken back into
signaling cell
• Fig 28.7
– Excitatory and
inhibitory signals
Types of neurotransmitters
• Most- small N containing organic molecules
• Acetylcholine- used in brain and between motor neurons
and muscle cells
• Biogenic amines- important in CNS
• Many drugs act out chemical signals
– Caffeine- countering effects of inhibitory neurotransmitters
=awake
– Nicotine- acts as a stimulant by binding to and activating
acetylcholine receptors
– Alcohol- depressant, inhibits effects of certain neurotransmitters
– Prozac- antidepressant, blocks removal of serotonin 
increasing amount of mood altering neurotransmitters available
– Amphetamines & cocaine- stimulants, increase in release and
availability of norepinephrine and dopamine
Nervous system organization correlates
with body symmetry
• Hydra-nerve net
• Cephalization- concentration of NS in head end
• Centralization- presence of CNS
Parts of our nervous system
• CNS
– Spinal cord- inside vertebral column- where reflexes are
controlled
– Blood-brain barrier- capillaries in brain restrict many substances
from entering
– Brain and SC- filled with cerebrospinal fluid- cushions CNS,
supplies nutrients, hormones WBC’s
– Meninges- layers of CT that protect CNS
– White matter- mainly axons (myelin sheaths)
– Gray matter- mainly nerve bodies and dendrites
– Cranial nerves- signal to and from brain
– Spinal nerves- 2 and from spine
Parts of our nervous system
• PNS (2 divisions)
– Sensory- senses internal and external env
– Motor – (2 divisions)
• Somatic- voluntary
• Autonomic- involuntary- regulates internal
environment
– Parasympathetic- primes body for digestion
and rest- activities that gain/conserve E
– Sympathetic- prepares body for intense E- E
consuming activities
The Brain
The brain
• Hindbrain and midbrain– Pons, medulla oblongata and
midbrain- brainstem- sensory
filter, regulates sleep,
coordinates body movement
– Pons and medulla oblongatacontrol breathing, and med. Obl.
also controls circulation,
swallowing, digestion
– Cerebellum- planning center for
body movements, learning and
remembering
The Brain
• Forebrain
– Thalamus- relay info to cerebral cortex
• Sorts data as to what goes to cerebrum and what comes out
– Hypothalamus- regulates basics (body temp, BP, thirst, hunger)
and biological clock- maintains daily biorhythms
– Cerebrum- consists of hemispheres- site of memory, learning,
emotion, speech, formulate complex behavior
• Left side of cerebrum- language, logic, math
• Right side- spatial, pattern, face recognition, music, emotional
processing
Limbic system
• Emotion, learning and memory
– Includes parts of thalamus, hypothalamus, amygdala and
hippocampus
– Amygdala- recognize emotion in facial expression and laying
down emotional memories
– Hippocampus- involved in formation of memories
– Moving from short to long term- enhanced by rehearsal, positive
or negative emotional states and association to previous learned
data