Chapter 3 - Anatomy of the Nervous System Flashcards
central nervous system (CNS)
division of the nervous system located within the skull and the spine; composed of two divisions –> the brain (skull) and the spinal cord (located in the spine)
peripheral nervous system (PNS)
division located outside the skull and the spine,
composed of two divisions: somatic nervous system (SNS) and automatic nervous system (ANS)
afferent nerves
carry sensory signals from the skin, skeletal muscles, joints, eyes, ear to the CNS
efferent nerves
carry motor signals from the CNS to the skeletal muscles
somatic nervous system (SNS)
part of the PNS that interacts with the external environment, composed of the afferent nerves and the efferent nerves
automatic nervous system (ANS)
part of the PNS that regulates the body’s internal environment
sympathetic nerves
automatic motor nerves that project from the CNS in the lumbar (small back) and the thoracic (chest area) regions of the spinal chord
parasympathetic nerves
automatic motor nerves that project from the brain and sacral (lower back) region of the spinal chord
cranial nerves
12 pairs of nerves extending from the brain (optic nerves, olfactory nerves, and vague nerves)
meninges
three protective membranes that cover the brain and the spinal cord
dura mater
outer meninx, though membrane
arachnoid membrane (spider web membrane)
immediately inside the dura mater
subarachnoid space
beneath the arachnoid membrane, contains many large blood vessels and cerebrospinal fluid
pia mater
innermost meninx, really delicate, adheres o the surface of the CNS
cerebrospinal fluid (CSF)
protects the CNS, fills the subarachnoid space, the central Canal of the spinal cord and the cerebral ventricles of the brain
central canal:
small central channel that runs the length of the spinal cord
cerebral ventricals
four large internal chambers of the brain: two lateral ventricles, the third ventricle and the fourth one
choroid plexuses
network of capillaries or small blood vessels that protrude into the ventricles from the Pia mater; produces CSF, the excess CSF is continuously absorbed from the subarachnoid space into large blood-filled spaces or dural sinuses
blood-brain barrier
a mechanism that impedes the passage of many toxic substances from the blood into the brain
neurons
cells that are specialized for reception, conduction and transmission of electrochemical signals; they come in an incredible variety of shapes and sizes
Neuron cell membrane
composed of a lipid bilayer, or two layers of fat molecules
external features of a neuron
cell body, myelin, cell membrane, dendrites, axon hillock, axon, nodes of ranvier, buttons, synapses
dendrites
the short processes emanating from the cell body, which receive most of the synaptic contacts from other neurons
axon hillock
the cone shaped region at the junction between the axon and the cell body
Myelin
the fatty insulation around many axons
axon
the long, narrow process that projects from the cell body
Nodes of Ranvier
the gaps between sections of myelin
buttons
the button like endings of the axon branches, which release chemicals into synapses
synapses
the gaps between adjacent neurons across which chemical signals are transmitted
major internal features of a neuron
endoplasmatic reticulum, cytoplasm, ribosomes, Golgi complex, nucleus, mitochondria, microtubules, synaptic ventricles, neurotransmitter
endoplasmatic reticulum
system of folded membranes in the cell body, rough portions (those with ribosomes) play a role in the synthesis of proteins; smooth portions (those without ribosomes) play a role in synthesis of fats
cytoplasm
the clear internal fluid of the cell
ribosomes
internal cellular structures on which proteins are synthesized; they are located on the endoplasmatic reticulum
Golgi complex
a connected system of membranes that packages molecules in vesicles
nucleus
the spherical DNA-containing structure of the cell body
mitochondria
sites of aerobic (oxygen-consuming) energy releases
> powerhouse of the cell