nervous system

• The nervous system is organized into the central and peripheral nervous system.
• Central nervous system (CNS): brain and spinal cord.
• Peripheral nervous system (PNS): all nerves.
• Autonomic nervous system (ANS): fibers that innervate smooth muscle, cardiac muscle, and glands.
• Further subdivided into the sympathetic and parasympathetic nervous system.
• Nitric oxide (NO) is a neurotransmitter.
• Acetylcholine (ACh) is a neurotransmitter.
• Catecholamines include Norepinephrine, dopamine, and serotonin.
• Enkephalins are neurotransmitters.
• Neurotransmitters are chemicals by which neurons communicate.
• Endorphins are neurotransmitters.
• Other compounds are neurotransmitters.
• The synapse is the place where impulses are transmitted from one neuron to another (the postsynaptic neuron).
• The synapse is made of three structures: synaptic knob, synaptic cleft, and plasma membrane.
• A stimulus triggers the opening of Na+ channels in the plasma membrane of the neuron.
• Neurotransmitters bind to specific receptor molecules in the membrane of a postsynaptic neuron, opening ion channels and thereby stimulating impulse conduction by the membrane.
• At rest, the neuron's membrane is slightly positive on the outside from a slight excess of sodium ions (Na+).
• The stimulated section of membrane immediately repolarizes, but by that time, the depolarization has already triggered the next section of membrane to depolarize, thus propagating a wave of electrical disturbances (depolarizations) all the way down the membrane.
• Three-neuron arcs consist of sensory neurons synapsing in the spinal cord with interneurons that synapse with motor neurons.
• Conduction by a reflex arc results in a reflex, such as a contraction by a muscle or secretion by a gland.
• Nerve impulses are self-propagating waves of electrical disturbance that travel along the surface of a neuron membrane, also called action potential.
• The simplest reflex arcs are two-neuron arcs, consisting of sensory neurons synapsing in the spinal cord with motor neurons.
• Inward movement of Na+ depolarizes the membrane by making the inside more positive than the outside at the stimulated point, this depolarization is a nerve impulse (action potential).
• Reflex arcs are pathways along which nerve impulses are conducted from receptors to effectors.
• Each neuron consists of three main parts: the cell body, dendrites, and axon.
• Interneurons conduct impulses from sensory neurons to motor neurors or among a network of interneurons, also known as central or connecting neurons.
• The Central Nervous System (CNS) consists of the brain and spinal cord.
• The Peripheral Nervous System (PNS) includes nerves and ganglia.
• Motor (efferent) neurons conduct impulses away from brain and spinal cord to muscles and glands.
• The Nervous System consists of the Central Nervous System (CNS) which includes the brain and spinal cord, and the Peripheral Nervous System (PNS) which includes nerves and ANS.
• The Central Nervous System (CNS) consists of the brain and spinal
• Axon is an elongated projection that conducts impulses away from the cell body of a neuron.
• Neurons are classified according to function as sensory (afferent) neurons, motor (efferent) neurons, and interneurons.
• Neurons consist of three main parts: the cell body, dendrites, and axon.
• Neurons are structured as follows: the cell body, dendrites, and axon.
• Sensory (afferent) neurons conduct impulses to the spinal cord and brain.
• Dendrites are branching projections that conduct impulses to the cell body of a neuron.
• The major anatomical components of the brain and spinal cord include the brainstem, cerebellum, cerebrum, diencephalon, hypothalamus, thalamus, and pineal gland.
• The brain is protected by a highly selective blood–brain barrier that regulates exchanges between the blood and brain.
• The brain is shielded from harmful changes by the fluids it contains.