Nervous System Chapter 48 and part of

Nervous System Functions – Electrochemical communication – Regulation and coordination of body – Homeostasis – 5 senses

Nervous System Structures – Brain – Spinal Cord – Neuron Sensory Neurons (receptors) Interneuron Motor Neurons Sensor Effector Motor output Integration Sensory input Peripheral nervous system (PNS) Central nervous system (CNS)

Neuron Structures Dendrites Cell body Nucleus Axon hillock Axon Myelin sheath Node of Ranvier Axon (synaptic) terminals Synapse – Electrical – Chemical Functions Receive signals from other neurons usually via neurotransmitters Contains the cell organelles Contains DNA Joins axon to cell body Transmits an electrical message – action potential Speeds up an action potential – insulates the axon – saltatory conduction Location of action potential – gap between myelin Release neurotransmitter to the dendrite of the next neuron Gap between the pre-synaptic and post- synaptic cell

Dendrites Cell body Nucleus Axon hillock Axon Signal direction Synapse Myelin sheath Synaptic terminals Presynaptic cell Postsynaptic cell

Diagram– structures and functions

POGIL – pgs 217 – 221 Neuron Structure

– + – – + – – + – – + – – + – – –– – + – + – – –– – –– – – –– – – –– –– – – – – – –– – – – – – –– – – Na + Action potential K+K+ K+K+ K+K+ Axon An action potential is generated as Na + flows inward across the membrane at one location. 1 2 The depolarization of the action potential spreads to the neighboring region of the membrane, re-initiating the action potential there. To the left of this region, the membrane is repolarizing as K + flows outward. 3 The depolarization-repolarization process is repeated in the next region of the membrane. In this way, local currents of ions across the plasma membrane cause the action potential to be propagated along the length of the axon. K+K+

Figure Presynaptic cell Postsynaptic cell Synaptic vesicles containing neurotransmitter Presynaptic membrane Postsynaptic membrane Voltage-gated Ca 2+ channel Synaptic cleft Ligand-gated ion channels Na + K+K+ Ligand- gated ion channel Postsynaptic membrane Neuro- transmitter 1 Ca

Reflex action (arc) Stimulus  sensory neuron  spinal cord (interneuron)  brain  spinal cord  motor neuron  muscle or gland

Peripheral nervous system Somatic nervous system Autonomic nervous system Sympathetic division Parasympathetic division Enteric division Organization Peripheral Nervous System (PNS) Cranial nerves Spinal nerves – Somatic nervous system – Autonomic nervous system Sympathetic Parasympathetic – Enteric – digestive system Central Nervous System (CNS) Brain Spinal cord

Organization Sympathetic “Fight or flight” Response to stressful situations Epinephrine (adrenaline) Fast heart beat Increased breathing Parasympathetic “Rest and digest” Calming and self- maintenance Decreases heart rate Enhances digestion

Parasympathetic divisionSympathetic division Action on target organs: Location of preganglionic neurons: brainstem and sacral segments of spinal cord Neurotransmitter released by preganglionic neurons: acetylcholine Location of postganglionic neurons: in ganglia close to or within target organs Neurotransmitter released by postganglionic neurons: acetylcholine Constricts pupil of eye Stimulates salivary gland secretion Constricts bronchi in lungs Slows heart Stimulates activity of stomach and intestines Stimulates activity of pancreas Stimulates gallbladder Promotes emptying of bladder Promotes erection of genitalia Cervical Thoracic Lumbar Synapse Sympathetic ganglia Dilates pupil of eye Inhibits salivary gland secretion Relaxes bronchi in lungs Accelerates heart Inhibits activity of stomach and intestines Inhibits activity of pancreas Stimulates glucose release from liver; inhibits gallbladder Stimulates adrenal medulla Inhibits emptying of bladder Promotes ejaculation and vaginal contractions Sacral Location of preganglionic neurons: thoracic and lumbar segments of spinal cord Neurotransmitter released by preganglionic neurons: acetylcholine Location of postganglionic neurons: some in ganglia close to target organs; others in a chain of ganglia near spinal cord Neurotransmitter released by postganglionic neurons: norepinephrine

Concept Map – divisions of the nervous system summarize

– POGIL Neuron Function

ACh Synaptic terminal of motor neuron Synaptic cleft T TUBULE PLASMA MEMBRANE SR ADP CYTOSOL Ca 2  P2P2

Thick filament Thin filaments Thin filament ATP ADP P i Cross-bridge Myosin head (low- energy configuration) Myosin head (high- energy configuration) + Myosin head (low- energy configuration) Thin filament moves toward center of sarcomere. Thick filament Actin Cross-bridge binding site

Thick filament Thin filaments Thin filament ATP ADP P i Cross-bridge Myosin head (low- energy configuration) Myosin head (high- energy configuration) + Myosin head (low- energy configuration) Thin filament moves toward center of sarcomere. Thick filament Actin Cross-bridge binding site Muscle Bundle of muscle fibers Single muscle fiber (cell) Plasma membrane Myofibril Light band Dark band Z line Sarcomere TEM 0.5  m I band A band I band M line Thick filaments (myosin) Thin filaments (actin) H zone Sarcomere Z line Nuclei

The Brain Structures Cerebrum – Cerebral cortex – outer portion of the cerebrum – gray matter – Cerebral hemispheres – left and right sides – Corpus callosum – allows communication between the left and right hemispheres Brainstem – Medulla oblongata – controls autonomic and homeostatic functions – Pons – regulates breathing – Midbrain – large scale body movements - walking Cerebellum – coordination, learning, and decision making Diencephalon – Thalamus – input center for sensory info and output center for motor info – Hypothalamus – homeostasis – links to the endocrine system

Cerebral Hemispheres Left Language Math Logical operations Visual and auditory details Right Pattern recognition Face recognition Spatial relations Nonverbal thinking Emotional processing Understanding and reacting to stress Music

Cerebral Cortex Frontal lobe – Speech Temporal lobe – Smell – Hearing Occipital lobe – Vision Parietal lobe – Speech – Taste – Reading

EK

Big Idea Summary