BP - F2024 - Nervous System

Central Nervous System

consists of brain and spinal cord; processes and responds to all messages from PNS

Spinal cord

bundle of nerves; extension of brain stem

Brain stem

nerve connections of motor and sensory systems from the rest of the body pass through this; includes midbrain, pons, and medulla oblongata

Peripheral Nervous System

allows the brain and spinal cord to receive and send information to other areas of the body which allows us to react to stimuli in our environment

Sensory Division

made up of afferent neurons that conduct impulses to the CNS from receptors that detect changes inside and outside the body; these include receptors for touch, smell, taste, hearing, sight, pain, body position (proprioception), and receptors in the viscera (internal organs) that indicate bladder fullness, stomach aches, blood pressure and more

Motor Division

made up of efferent neurons that conduct impulses away from the CNS to the muscles and glands, allowing the brain to control heart rate, blood pressure, breathing rate, sweat production, and hormone release, among other functions

Somatic Nervous System

responsible for voluntary movement of muscles and the process known as a reflex arc, a system that carries nerve impulses back and forth between the CNS and the skeletal muscles, skin, and sensory organs

Autonomic Nervous System

responsible for involuntary functions inside the body; communicates with internal organs and glands to regulate body processes that take place without conscious effort including heartbeat, pupil dilation, blood flow, breathing, and digestion

Sympathetic Division

regulates flight-or-fight responses; performs tasks including relaxing the bladder, speeding up heart rate, slowing digestion, and dilating pupils

Parasympathetic Division

helps maintain normal body functions and conserves physical resources; performs tasks including controlling the bladder, slowing down heart rate, normalizing digestion, and constricting pupils

Glial cells

neuron partner; surround and protect neurons; provide immune defense by destroying pathogens; remove dead neurons; help form myelin sheaths, regulate ions

Neuron

electrically excitable cell that transmits information throughout the nervous system through electrical and chemical signals

Interneurons

these are found only in the CNS and transmit messages between the CNS and the sensory and motor neurons of the PNS

Nerve

collection of neuron fibers (axons) bundled with blood vessels and connective tissue; carry impulses between the CNS and other parts of the body; most have axons of both sensory and motor neurons

Axon

long threadlike part of a neuron that sends impulses to other cells

Dendrite

short branched extension of neuron that receives impulses from other cells at synapses

Synapse

site of transmission of electric nerve impulses between two neurons or between a neuron and a gland or muscle cell

Neurotransmitter

chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and transfers the impulse to another neuron, gland, or muscle cell

Action potential

the brief (~1/1000 of a second) reversal of electric polarization of the membrane of a neuron or muscle cell; in the neuron it produces the nerve impulse; in the muscle cell it produces the contraction required for movement

Myelin sheath

fatty white substance that forms protective coating around axons in the CNS; insulates and protects and helps speed transmission of nerve impulses

Reflex arc

results when sensory neurons activate spinal motor neurons which activate muscles cells before routing signals through the brain for analysis

PNS branches

Sensory & Motor Divisions

Motor Division branches

Somatic & Autonomic Nervous Systems

Autonomic Nervous System branches

Sympathetic & Parasympathetic Nervous Systems

synaptic terminal

the location where axons terminate at the synapse for transmission of information by the release of a chemical transmitter