Organization of the Nervous System:
Composed of the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
Components: Brain and spinal cord.
Functions: Acts as the integrating center for processing sensory information and directing responses.
Divisions:
Afferent Division: Sensory neurons that send information to the CNS.
Efferent Division:
Somatic Motor: Controls skeletal muscle.
Autonomic: Controls smooth and cardiac muscle, as well as glands.
Neurons: Basic functional unit of the nervous system.
Structure: Consist of dendrites, an axon, and synaptic terminals.
Types of Neurons:
Presynaptic Neuron: Sends signals.
Postsynaptic Neuron: Receives signals.
Glial Cells: Support neurons, outnumber them by 10-50 times.
Resting Membrane Potential: Electrical potential difference across the membrane at rest.
Key Ions:
Extracellular: High in Na+ and Cl-.
Intracellular: High in K+ and negatively charged proteins.
Equilibrium Potential: Net flux of an ion across a membrane is zero, described by the Nernst equation.
Graded Potentials:
Changes in membrane potential that vary in size.
Subthreshold and Suprathreshold:
Subthreshold: Too weak to trigger an action potential.
Suprathreshold: Strong enough to initiate an action potential.
Action Potentials:
All-or-nothing response when a stimulus reaches threshold.
Characteristics:
Frequency of action potentials reflects stimulus strength.
Conducted without loss of strength along the axon.
Saltatory Conduction:
Occurs along myelinated axons, greatly increasing conduction speed.
Myelin Formation:
PNS: Schwann cells individually myelinate axons.
CNS: Oligodendrocytes myelinate multiple axons.
White vs. Grey Matter:
White Matter: Myelinated axons.
Grey Matter: Neuron cell bodies and unmyelinated axons.
Physical Protection:
Bony Structures: Skull and vertebrae.
Meninges: Three protective membranes:
Dura Mater: Outer layer.
Arachnoid Membrane: Middle layer.
Pia Mater: Inner layer, adheres to the brain and spinal cord.
Cerebrospinal Fluid (CSF): Provides cushioning and chemical stability.
Blood-Brain Barrier: Selectively permeable barrier that protects the brain from harmful substances in the blood.
Cerebrum: Largest part of the brain, involved in higher brain functions.
Cerebellum: Coordinates movement and maintains posture.
Brainstem: Controls vital functions and pathways between the brain and spinal cord.
Limbic System: Involved in emotion and memory.
Frontal Lobe: Involved in executive functions and voluntary motor control.
Parietal Lobe: Processes sensory information.
Temporal Lobe: Involved in auditory information and memory.
Occipital Lobe: Responsible for visual processing.
Ascending Tracts: Carry sensory information to the brain.
Descending Tracts: Convey motor commands from the brain to the body.
Dorsal/Ventral Roots: Dorsal roots carry sensory information, ventral roots carry motor signals.
Electroencephalography (EEG): Measures brain electrical activity.
Positron Emission Tomography (PET): Measures brain metabolism using radioactive tracers.
Functional Magnetic Resonance Imaging (fMRI): Measures brain activity by detecting changes in blood flow.
Understand the organization and protective mechanisms of the CNS.
Describe the anatomy and function of different brain regions.
Comprehend cellular mechanisms involved in neuronal signaling and communication.
Central Nervous System (CNS)