Chapters 48 & 49 Campbell Biology – 9th ed. Nervous Systems Chapters 48 & 49 Campbell Biology – 9th ed.

You must know The anatomy of a neuron. The mechanisms of impulse transmission in a neuron. The process that leads to release of neurotransmitters, and what happens at the synapse. How the vertebrate brain integrates information, which leads to an appropriate response. Different regions of the brain have different functions.

Organization of the Nervous System Central nervous system (CNS) = _______+ ___________ Peripheral nervous system (PNS) = _________________ Sensory receptors: _______________________ Sensory _____________: body  CNS _____________ neurons: CNS  body (muscles, glands) ______________________: connect sensory & motor neurons Nerves = _____________________________________ Contains motor neurons and/or sensory neurons

Peripheral Nervous System Somatic nervous system Autonomic nervous system Sympathetic division Parasympathetic division Enteric division

Neuron = ______ + __________+ ______

Neuron __________________: contains nucleus & organelles ___________________: receive incoming messages ________: transmit messages ________ to other cells myelin sheath: _____________ insulation covering axon, ________________________nerve impulses ___________________: junction between 2 neurons _____________________: ______________ messengers sent across synapse __________: cells that _______________ neurons Eg. _____________________(forms myelin sheath)

Schwann cells and the myelin sheath

___________________________: difference in electrical charge across cell membrane Microelectrode –70 mV Voltage recorder Reference electrode

The ________________ pump (using ATP) maintains a ________________ potential ________________ the neuron.

_____________________(nerve impulses) are the signals conducted by __________ _____________________: membrane potential at rest; __________________ Na+ ___________, K+ _______________ cell Voltage-gated Na+ channel = __________________ ________________________: stimulus causes a change in membrane potential Action potential: neuron membrane depolarizes __________________________ response _____channels open _____ channels open Na+ enters cell K+ leaves cell

Conduction of an action potential

Action Potential The resting potential of a neuron is -70 mV Stimulus (and depolarization) must reach the Threshold of -55 mV in order for an action potential to occur = “all or none” response

Saltatory conduction speed: 120 m/sec ____________________________: nerve impulse ______ between ___________________________________ (unmyelinated gaps)  speeds up impulse Saltatory conduction speed: 120 m/sec

Cell communication: neurotransmitter released at synapses Axon (presynaptic cell)  Dendrite (postsynaptic cell)

Neurotransmitters Chemicals released from vesicles by _________________ into _________________________________ Diffuse across _____________________ Bind to _________________________ on neurons, muscle cells, or gland cells Broken down by enzymes or taken back up into surrounding cells Types of neurotransmitters: __________________: speed up impulses by causing depolarization of postsynaptic membrane __________________: : slow impulses by causing hyperpolarization of postsynaptic membrane

Examples of Neurotransmitters Acetylcholine (ACh): stimulates muscles, memory formation, learning ____________________: (adrenaline) fight-or-flight Norepinephrine: ____________________________ ______________: reward, pleasure (“high”) Loss of dopamine  _________________ Disease __________________: well-being, happiness Low levels  ___________________ _______________: inhibitory neurotransmitter Affected by alcohol

Reflexes Simple, automatic response to a stimulus Conscious thought not required Reflex arc: (components) Stimulus detected by _________________ ___________________ neuron Interneuron (spinal cord or brain stem) Response by _________ organ (muscles, glands)

Knee-jerk reflex

Evolution of Nervous Systems

Vertebrate brain is regionally specialized Major Regions: forebrain, midbrain, hindbrain

Forebrain  __________________ Midbrain  ___________________ Hindbrain  __________________

Human Brain Structure Function Cerebrum Brainstem Cerebellum _________________________________(learning, emotion, memory, perception, voluntary movement) Right & Left cerebral hemispheres _____________________: connect hemispheres Brainstem *_______________________________________* Basic, ____________________ survival behaviors Medulla oblongata –___________________, heart & blood vessel activity, ________________, swallowing, vomiting Transfer info between PNS & CNS Cerebellum Coordinate ___________________ & balance Motor skill learning

__________________: neuron cell bodies, __________________________ axons __________________: fatty, ___________________ axons