Chapter 28- Nervous System• 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

• 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 oblongata- control 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