anatomy and physiology - nervous system quiz

function of the nervous system

ultimate control center of the body overseeing all communication among organ systems

sensory input

receives stimuli via millions of sensory receptors throughout the body

integration

processes the input stimuli and decides what should be done

motor output

activates effector organs to cause a response

central nervous system (cns)

consists of the brain and spinal cord

peripheral nervous system (pns)

consists of the other nerves throughout the body. Cranial nerves: originate in the brain and spinal nerves: originate in the spinal cord.

sensory (afferent) division

sends impulses from the senses to the CNS

motor (efferent) division

sends impulses from the CNS to the muscles and glands

autonomic nervous system

involuntary muscle control (heart, lungs, stomach, etc.) uses norepinephrine (NE)

somatic nervous system

voluntary muscle control (skeletal muscle) Neuromuscular junction uses Ach

sympathetic division

used in emergency situations (“fight or flight”) –”excites you”

parasympathetic division

reduces sympathetic response and provides resting functions such as digestion and urination “calms you down”

neurons (nerve cells)

excitable cells that respond to stimuli by conducting impulses to transmit signals

neuroglia (glial cells)

supportive cells that provide nutrition, insulation, and help with signal transmission, found both in CNS and PNS

astrocytes (CNS)

support & anchor neurons to surrounding capillaries

microglia (CNS)

provide immune response to central Nervous system

ependymal (CNS)

secrete and circulate cerebrospinal fluid

oligodendrocytes (CNS)

provide myelin insulation to neurons in the central nervous system

schwann cells (PNS)

form myelin around neurons of the PNS.

satelittle cells (PNS)

support and anchor neurons to the PNS.

soma (cell body)

the life support containing the nucleus and most organelles (such as tons of mitochondria)

ganglion

collection of nerve cell bodies located in the body (just not the brain or spinal cord)

processes

extensions from the cell body

dendrites

the main receptor of signals; input region

axon

generates and transmits nerve impulses; the conducting region; also known as a nerve fiber

nerves

bundles of axons that extend from the brain and spinal cord to the rest of the body

axon terminals

the end of the axon that releases neurotransmitters at a synapse when a nerve impulse is received; the secretory region

myelin sheath

covers long axons (nerve fibers) to protect and electrically insulate them to increase the speed of nerve impulse transmission

nodes of ranvier

unmyelinated gaps in the myelin sheath that aid in increasing the velocity of nerve signal conduction

how are neurons classified structurally?

based on the number of processes (extensions) from the cell body

multipolar

>3 processes (1 axon and 2 or more dendrites), 99% of neurons are multipolar

bipolar

2 process (1 axon and 1 dendrite on opposite ends of the cell), this is rare and found in a few special sense organs

unipolar

1 process, dividing from the cell body like a T, in the ganglia in the PNS

how are neurons classified functionally?

based on the way an impulse travels through a neuron with regards to the brain and spine

sensory neurons (afferent neurons)

transmit info from sensory receptors to CNS, most are structurally unipolar

interneurons (association neurons)

housed in the CNS and transport info between the sensory and motor neurons, most are structurally multipolar

motor neurons (efferent neurons)

transport info from CNS to rest of the body, most are structurally multipolar to send impulse to multiple places

meninges

layers of tissues that surround the skull (dura matter, arachnoid, and pia mater)

cerebrospinal fluid

cushions brain from injury

ventricles

hollow fluid-filled cavities within brain that contain the choroid plexus which makes cerebrospinal fluid

neurotransmitters

chemicals released from neurons to cross synapses

hormones

chemicals released from glands into the bloodstream

mechanoreceptors

mechanical force, like vibration, pressure, stretch, and touch

thermoreceptors

change in temperature

photoreceptors

light

chemoreceptors

chemicals

nociceptors

pain

reflex

an automatic reaction to stimuli

innate (intrinsic)

a rapid, predictable motor response to a startling stimulus

learned (acquired)

a response resulting from practice, repetition, or experience

reflex arcs

highly specific neural pathways

nerve impulse

an electrical signal that travels along the neuron. It arises from the movement of ions causing a change in electrical charges.

resting potential

a neuron’s intracellular space is negatively charged and the extracellular space is positively charged.

action potential

when the neuron is stimulated, either by the environment or another neuron, sodium rushes into the neuron and quickly reverses the charges (called depolarization)

how does resting potential return

as the impulse passes, potassium diffuses out of the neuron (repolarization). The sodium-potassium pump then restores the ion concentrations to normal

synapse

where 2 neurons meet, they don’t touch

synaptic cleft

space between the neurons in synapse