The nervous system integrates and controls other body systems by receiving information, processing information and sending out signals to muscles and glands to elicit appropriate responses.

The 2 parts of the nervous system are the central nervous system and the peripheral nervous system.

The central nervous system is protected by the skull and vertebrae.

Collections of cell bodies inside the CNS are called nuclei, and the collections of nerve axons in the CNS are called tracts.

The peripheral nervous system includes the cranial nerves and spinal nerves.

Collections of cell bodies in the PNS are called ganglia, and the collection of nerve axons in the PNS are called nerves.

The 2 divisions of the PNS are sensory/afferent and motor/efferent.

The PNS receives impulses from sensory organs via the afferent division and then relays signals of impulses from the CNS to the muscles and glands via the efferent system.

The efferent division of the PNS is divided into the somatic system (under conscious control) and the autonomic system (involuntary).

The somatic system controls the movement of skeletal muscles, skin and joints. The autonomic system controls the glands and smooth muscles of internal organs.

The 2 divisions of the autonomic nervous system are the sympathetic and parasympathetic nervous system.

The sympathetic nervous system activates and prepares the body for vigorous muscular activity, stress and emergencies.

The parasympathetic nervous system operates during normal situations, permits digestion and conserves energy.

Label the components of a neuron.

Neurons do not undergo mitosis (cell division). Neurons can survive a person's entire lifetime. Neurons can survive just minutes without oxygen.

All neurons contain dendrites, a cell body and an axon.

The neuron cell body synthesizes all nerve cell products. It receives info from the dendrites and sends info towards the axon. It has a large nucleus with surrounding cytoplasm containing the normal organelles (except for centrioles, which are responsible for mitosis).

Dendrites are numerous short extensions from the cell body. The dendrite receives information from other neurons and conducts impulses to the cell body.

There is a single axon in each neuron responsible for conducting nerve impulses away from the cell body to the axon terminals. Axons are composed of cell organelles but lack a rough endoplasmic reticulum because they rely on the cell body to send necessary proteins down the axon.

Neurotransmitters are synthesized in the cell body and stored inside secretory vesicles at the end of axon terminals. Neurotransmitters are chemical messengers that communicate between neurons across a synapse.

A synapse is a gap between 2 neurons.

A postsynaptic neuron is a neuron that is found after the synapse.

Multipolar neurons have three or more extensions from the cell body and have one axon and many dendrites.

Bipolar neurons have a central cell body with two extensions.

Unipolar neurons have one extension of the cell body which branches into two: one central process running to the CNS and another peripheral process running to the sensory receptor.

Sensory neurons are unipolar and function to carry information from the PNS to the CNS.

Interneurons are also called association neurons.

Motor neurons send messages from the CNS to the PNS.

The function of neuroglial cells is to help support neurons to enable them to thrive in their environment.

The peripheral nervous system neuroglial cells are Schwann cells (myelin sheath) and satellite cells (help to regulate the cell body environment).

Axons can regenerate in the PNS.

Myelin sheath is not continuous and has gaps called nodes of ranvier.

Neuroglial cells in the CNS: Ependymal cells circulate CSF and allow fluid exchange between brain, spinal cord and CSF. Oligodendrocytes act as the insulation for the CNS axons. Astrocytes control the chemical environment of neurons by wrapping around the blood capillaries, creating the blood brain barrier. Microglial cells protect the CNS by scavenging dead cells and infectious microorganisms.

An action potential causes a nerve impulse. It's an electrochemical charge moving along an axon created by the movement of unequally distributed ions on either side of an axon's plasma membrane.

A resting potential of -70 means that the charge on the inside of the axon's cell membrane is 70 mv less than the outside of the membrane. The sodium potassium ion pump maintains this potential by pumping in 2 K+ ions for every 3 Na+ ions pumped out.

The 4 steps of an action potential are resting state, depolarization, depolarization and after polarization.

During depolarization to voltage increases to +40mv when the Na+ gates open and Na+ rushes into the axon.

During repolarization the Na+ gates close and K+ gates open allowing K+ to rush out of the axon. This returns a negative voltage to the inside of the axon.

During after polarization K+ gates are slow to close causing the voltage to drop below -70mv.

The difference in intensity of sensations is distinguished by the number of neurons stimulated and the frequency with which neurons are stimulated.

An impulse from a neuron does not move in both directions.

The transmission of a nerve impulse is electrochemical because neurotransmitters allow the signal to cross the synaptic gap.

The chemical portion of neuron signal transmission is carried out by Neuro transmitters.

When an impulse reaches the end of an axon voltage-gated Ca+ channels open. Ca+ ions rush in, causing vesicles containing the neurotransmitter to fuse with the plasma membrane and release the neurotransmitter into the synapse. The neurotransmitter then bends with a receptor on the next neuron, causing Na+ channels in the receiving dendrites to open and triggering an action potential.

The short existence of neurotransmitters in a synapse prevents continuous stimulation of a neuron, aka inhibition.

Dopamine helps regulate emotional responses and muscle tone.

Acetylcholine is found at neuromuscular junctions in the PNS.

After its released into the synapse, acetylcholine binds to receptors on the muscle fiber that cause Na+ ion channels to open. This triggers an action potential that reaches the sarcoplasmic reticulum. Then, Ca+ ions are released from the sarcoplasmic reticulum of the muscle cell, causing the muscle to contract.

A reflex is a nearly instantaneous, automatic and involuntary motor response within the nervous system. An internal example is the regulation of blood sugar with hormones. An external example is shivering in response to being cold.

Sensory information travels to the spinal cord via the dorsal root of a nerve.

The gray matter of the spinal cord contains the cell bodies of neurons and interneurons. The white matter of the spinal cord contains the axons of neurons.

The DRG contains the cell bodies of sensory neurons.

Sensory neurons synapse on cells in the posterior horn of the spinal cord in the gray matter.

Motor neuron cell bodies are in the anterior horn of the gray matter of the spinal cord.

Motor neuron axons leave the spinal cord via the ventral root.

The ventral root transitions to a spinal nerve when it meets the dorsal root.

Label the components of a cross section of a spinal cord.

A spinal reflex is faster than a conscious decision to move because it involves fewer neurons and doesn't have to travel to the brain and back.

The 5 components of a reflex arc are the receptor at the end of a sensory neuron reacts to a stimulus, the sensory neuron conducts nerve impulses along an afferent pathway to the CNS. the integration center consists of one or more synapses in the CNS, a motor neuron conducts a nerve impulse along an efferent pathway to an effector, an effector responds to the efferent impulses by contracting or secreting a product.

The stretch reflex utilizes a muscle spindle to detect overstretch.

The stretch reflex prevents increases in length that could cause a tear or damaged muscle fibers.