Nervous System

• The nervous system is the main control center, together with the endocrine system, aiming to maintain homeostasis and providing quick and brief responses.
• The nervous system monitors the body’s internal and external environments, integrates sensory information, and coordinates voluntary and involuntary responses of many other organ systems.
• The optic nerve splits to go to the thalamus.
• • Explain the function of the structures of the external, middle, and internal ears.
• The optic nerve meets the optic nerve of the other eye at the optic chiasm.
• The central nervous system (CNS) consists of the brain and the spinal cord, integrates, processes, and coordinates sensory input and motor commands.
• The peripheral nervous system (PNS) includes all the neural tissue outside the CNS, carries the information between the CNS and rest of the body.
• Spinal nerves connect to the spinal cord.
• The Peripheral Nervous System consists of 12 pairs of cranial nerves, designated with Roman numerals I through XII.
• Cranial nerves are classified as primarily sensory, primarily motor, or mixed (both sensory and motor).
• The Peripheral Nervous System (PNS) links the Central Nervous System (CNS) to the rest of the body through peripheral nerves.
• Cranial nerves originate from the brain.
• Four cranial nerves also contain additional parasympathetic autonomic fibres: CN III, CN VII, CN IX, CN X.
• CN X is the most important, with extensive parasympathetic fibres to many internal organs.
• The afferent division of the peripheral nervous system carries sensory information from sensory receptors to the CNS, these receptors are sensory structures that either detect changes in the environment or respond to a specific stimuli.
• The efferent division of the peripheral nervous system carries motor commands from the CNS to effectors, these target organs and tissues respond by doing something, hence they are called effectors.
• Pons links the cerebellum with the brain stem and the spinal cord.
• Cerebellum is the 2nd largest part of the brain, has two hemispheres, and is connected by the vermis.
• Nuclei for cranial nerves IX to XII are located in Medulla Oblongata.
• Medulla Oblongata connects the brain to the spinal cord and functions as a relay between the spinal cord and the brain.
• Cerebellum contains two important functions: adjusting postural muscles to maintain balance and programming, fine-tuning, and smoothening voluntary and involuntary movements.
• Substantia nigra, red nucleus, is responsible for involuntary movements.
• Medulla Oblongata contains autonomic centers, vasomotor center, respiratory centers, and reflex centers for coughing, vomiting, sneezing, and swallowing.
• Cerebellum does not initiate movement, but damage to it causes ataxia, a disturbance in balance and gait.
• Pons contains respiratory centers and nuclei for cranial nerves V to VIII.
• The Cerebrum is the largest component of brain and controls higher mental functions such as conscious thought and intellectual functions.
• Gyrus is the singular form of Gyri, and Sulcus is the singular form of Sulci.
• The Cerebral Hemisphere contains numerous folds and depressions known as gyri, which are elevated ridges that increase surface area of cortex.
• The Cerebrum is divided into four lobes: Frontal lobe, Parietal lobe, Temporal lobe, and Occipital lobe.
• The Cerebral Hemisphere also contains sulci, which are shallow depressions.
• The Cerebrum is divided into two hemispheres which are connected by corpus callosum.
• The Cerebral Hemisphere contains fissures, which are deep grooves.
• Multipolar neurons contain numerous mitochondria which produce energy.
• Multipolar neurons are the most common neurons in the Central Nervous System (CNS).
• The functional classification of neurons includes multipolar, unipolar, and bipolar neurons.
• The axon in a multipolar neuron is single and long, transmits electrical signal, and has branches (collaterals) which end in axon terminals.
• The structure of a multipolar neuron includes a large round nucleus, a prominent nucleolus, no centrioles, and cannot divide, regenerate, or be replaced if lost to injury or disease.
• The structural classification of neurons is based on the relationship of the dendrites to the cell body and axon, and includes multipolar neurons, unipolar neurons, and bipolar neurons.
• Dendrites in a multipolar neuron are many, short, branched, and are sensitive to stimulation.
• Multipolar neurons communicate with other cells via synapses.