The Nervous System
Nervous System Nervous System: Collects information, processes, and responds to internal and external environment
Overview of Nervous System Stimulus: Something in environment causes a response Neuron: Cell that receive, conduct, and transmit impulses Response: Reaction to environmental conditions synapse RESPONSE!
The Neuron Neurons build into nerves!
Parts of the Neuron Dendrites Receive messages from previous neurons Send message to cell body Cell Body Contains nucleus and cytoplasm
Parts of the Neuron: Cont’d Axon Long fiber that carries messages away from the cell body Myelin Sheath Insulating membrane helps send the signal down the axon Nodes of Ranvier Gaps between Schwann Cells Impulse jumps from one node to next Schwann Cells Supporting cells that wrap around the myelin sheath
Parts of the Neuron: Cont’d Axon Terminals Branches at the end of an axon Contain synapses where neurotransmitters are released
Synapses Synapse Space between neurons Carry messages or impulses from one nerve to the next Neurotransmitters Chemical messages sent between neurons Diffuse to next neuron
How does a neuron work? Summary Neurotransmitter received from another neuron in dendrites & through cell body Impulse travels down the axon Neurotransmitter released into synapse Neurotransmitter received by protein receptors in dendrites of next neuron
A closer look at how an impulse travels down the axon Polarization- differences in charge ( + or -) Electrical charges are different inside a neuron compared to outside Caused by K+ and Na+ K+ and Na+ can move through channels within the axon membrane
A closer look at how an impulse travels down the axon Impulse is carried down the axon Resting Negative inside (-70 mV) Active- Impulse in progress Positive inside (+40 mV)
How does a neuron work? http://outreach.mcb.harvard.edu/animations/actionpotential.swf
Receptor & Sensory Neurons Types of Neurons Motor Neuron (Spinal Cord and Brain Muscles and Glands) Receptor & Sensory Neurons (Sensory Organs Spinal Cord and Brain) Interneurons Sends Messages between Nerves (Sensory, Receptor, Motor, and other Interneurons)
Reflex Arc No brain involved! Receptor Afferent Neurons Sensory Neuron Spinal Cord Interneuron Efferent Neurons Motor Neuron Effector (Muscle)
Central Nervous System (CNS) Consists of the brain and spinal column
Spinal Cord Gray Matter White Matter Consists of cell bodies Consists of axons
Parts of the Brain Meninges- protective covering of the brain/spinal cord Corpus Collasum Occipital
Brain Area Function Meninges Protection of spinal cord and brain Cerebrum Memory center Cerebellum Coordination and balance Medulla Involuntary processes Spinal Cord Nerves from brain Thalamus Relay center between brain and spinal cord Occipital Vision & Hearing Hypothalamus Homeostasis- hunger, thirst, hormones Links endocrine to nervous system Corpus Collasum Connects left and right brain
Peripheral Nervous System Peripheral Nervous System- connects the central nervous system to the rest of the body Somatic- voluntary Autonomic- involuntary Parasympathetic- at rest Sympathetic- fight or flight
Malfunctions Meningitis- swelling of meninges Cerebral Palsy- birth defect, affects muscle coordination Stroke- blood clot to the brain Polio- viral illness Multiple sclerosis (MS)- break down of myelin sheath- impairs movement
Malfunctions Drug Addictions Stimulants Depressants Increase the number of neurotransmitters Depressants Decrease the number of neurotransmitters