Nervous Tissue Flashcards
the nervous system
- the central processing unit (CPU) of the body
- utilization of the neuroendocrine system & endocrine systems for short term and long term responses
- the master controlling & communication sys. of the body
how is the nervous system organized?
composed of two parts; the CNS (central nervous system) & PNS (peripheral nervous system)
central nervous system
- consists of the BRAIN & SPINAL CORD
- helps with integration, processing, coordinating info, and higher brain functions
peripheral nervous system
- variation of NERVES + other NEURAL TISSUE outside of the CNS
- has two functional divisions:
the AFFERENT (SENSORY) DIVISION & the EFFERENT (MOTOR) DIVISION
types of inputs/information
- SENSORY INPUT:
- info gathered by SENSORY RECEPTORS about INTERNAL & EXTERNAL CHANGES (AFFERENT DIVISION)
ex. senses, sight, hearing
[INTEGRATION: where the PROCESSING & INTERPRETATION OF SENSORY INPUT - decides on the approp. behavior aka the BRAIN]
- MOTOR OUTPUT:
- activator becomes active and CREATION OF “WORK” in RESPONSE (EFFERENT DIVISION)
ex. muscle, joint, or hormone
sensory (afferent) division of the PNS
brings sensory info to the CNS from receptors through the body
- also has TWO DIVISIONS:
- SOMATIC SENSORY DIVISION/FIBERS:
- sensory info from muscles, joints, and special senses, to the CNS - VISCERAL SENSORY DIVISION/FIBERS:
- sensory info from VISCERAL ORGANS to CNS
(smooth/cardiac muscle, digestive organs, etc…)
somatic nervous system [motor division]
- is controlled by SOMATIC MOTOR NERVE FIBERS
- conducts impulses from CNS to skeletal muscle/actions
- this is a VOLUNTARY NERVOUS SYS. (conscious control of skeletal muscles)
motor (efferent) division of the PNS
responsible for transmitting impulses from CNS to EFFECTOR ORGANS:
- often seen in muscles & glands
- also divided into TWO SYSTEMS:
1. SOMATIC NERVOUS SYSTEM
2. AUTONOMIC NERVOUS SYSTEm
autonomic nervous system [motor division]
- controlled by VISCERAL NERVOUS FIBERS
- helps with the regulation of SMOOTH MUSCLE, CARDIAC MUSCLE, & GLANDS
- ## this is an INVOLUNTARY NERVOUS SYS.also has two SUBDIVISIONS:
- SYMPATHETIC: fight or flight response
- PARASYMPATHETIC: rest & digest response
*both work in opposition
cells of the nervous system
- NEUROGLIA/GLIAL CELLS
- helps with support, regulation, and protection of neurons - NEURONS (NERVE CELLS)
- helps conduct ELECTRICAL SIGNALS
- aid in PROCESSING, TRANSFER, & STORAGE OF INFO
what are the CNS glial cells?
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
what are the PNS glial cells?
- schwann cells (neurolemmocytes)
- satellite cells
astrocytes
- most ABUNDANT + VERSATILE + HIGHLY BRANCHED glial cells
- most LARGEST
- helps control the CHEMICAL/INTERSTITIAL ENVIRONMENT and alter NERVE CELL FUNCTION
- helps with structural framework/braces neurons
- creates blood-brain barrier for capillaries and neurons
(the satellite cells of the CNS)
oligodendrocytes
- creates MYELIN SHEATHS around CNS NERVE FIBERS/AXONS
- can often appear WHITE in appearance
- gives proper STRUCTURAL FRAMEWORK
- helps SPEED UP ACTION POTENTIALS
(the schwann cells of the CNS)
microglia
- SMALLEST of all glial cells the “clean-up squad”
- helps injured neurons and helps as PHAGOCYTIC CELLS
- known as the “DEFENSE CELLS”
- LEAST NUMEROUS NEUROGLIAL CELLS
ependymal cells
- often shaped like SQUAMOUS or COLUMNAR CELLS (can also have microvilli or cilia)
- often line our BRAIN & SPINAL CORD CAVITIES
- assist in the PRODUCTION, CIRCULATION, & MONITORING of CSF
schwann cells
- helps form the MYELIN SHEATH in the PNS
- surrounds the PERIPHERAL AXONS
helps with NERVE FUNCTION RECOVERY
(the oligodendrocytes of the PNS)
satellite cells
- helps with the PROTECTION OF NEURON CELL BODIES
- helps with REGULATION OF EXCHANGING of MATERIAL between neurons
neuron anatomy/structure
DENDRITES:
- stimulation by any environmental changes or activities
- conveys its messages to the cell body through GRADED POTENTIALS (short distance)
CELL BODY:
- contains nucleus & mitochondria, ribosomes, or other organelles
- picks up SIGNALS from DENDRITES
AXON HILLOCK:
- part of the cell body that connects to the axon (helps control the ELECTRICAL IMPULSE)
AXON:
- transmission begins in AXOLEMMA
- conducts the NERVE IMPULSE (AP) toward the synaptic terminals
- ends with the AXON TERMINAL
TELODENRIA (branches):
- helps with the establishment of FXN. CONTACT with the OTHER NERVE CELLS
SYNAPTIC TERMINALS:
- affects another neuron/effector organ (muscle or gland)
neuron cell body
- the BIOSYNTHETIC CENTER OF THE NEURON
- SYNTHESIZES proteins, membranes, and other chemicals
- ## part of the ROUGH ER
- NUCLEI:
clusters of neuron cell bodies within the CNS - GANGLIA:
lies along nerves in PNS
myelin sheaths
- consists of MYELIN
- a WHITEISH, PROTEIN-LIPOID SUBSTANCE
- ## wrap around LONG AXONS
- helps PROTECT & INSULATE AXONS
- helps INCREASE SPEED of NERVE IMPULSE TRANSMISSION
(non-myelinated fibers CONDUCT IMPULSES MORE SLOWLY)
structural classification of neurons
MULTIPOLAR:
- has ONE AXON
- has THREE or MORE PROCESSES
- dendrites
- most COMMON; a MAJOR NEURON in the CNS
- considered to be INTERNEURONS or MOTOR NEURONS
BIPOLAR:
- has ONE AXON/ONE DENDRITE
- has TWO PROCESSES (separated by CELL BODY)
- typically considered to be a SENSORY NEURONS (often more RARE - seen in retina & olfactory mucosa)
UNIPOLAR/PSEUDOUNIPOLAR:
- has only ONE SHORT PROCESS
- both branches are considered AXONS - divides like the LETTER “T”
- often considered SENSORY NEURONS
demyelination disorders
disorders or diseases that can destroy myelin/myelinated axons within the CNS or PNS
multiple sclerosis
the demyelination of the axons within the OPTIC NERVE, BRAIN, and SPINAL CORD
- progressive and there is NO CURE
- often between ages 30-40
- w>m
heavy metal poisoning
chronic exposure to lead, mercury, arsenic which can cause demyelination of the axons in PNS/CNS
- mercury espec. can lead to BIRTH DEFECTS due to DESTRUCTION of ASTROCYTES
describe the electrical signaling of the membrane potentials
MEMBRANE POTENTIAL:
the ELECTRICAL CHARGE across the MEMBRANE of every cell in your body
(often relies on the ELECTROLYTES/IONS within BODY
DISTRIBUTION:
- uneven dist. of CATIONS and ANIONS across the cell membrane creating an UNEVEN ELECTRICAL EQUILIBRIUM
what are the principles of electricity?
well, what is ELECTRICITY?
- the MOVEMENT OF ELECTRIONS
these ELECTRONS have OPPOSITE CHARGES that ATTRACT EACH OTHER (due to the Law of Conservation of Electrical Charge - cation+anion)
- ENERGY IS REQUIRED IN THIS
- ENERGY IS LIBERATED when CHARGES MOVE TOWARD EACH OTHER
———————————————————————SEPARATION: the system now has POTENTIAL ENERGY
how are insulators & conductors related to electricity?
both INSULATORS & CONDUCTORS are types of RESISTANCES to these CHARGES:
- INSULATOR:
a substance with HIGH electrical resistance; material that separates charges if they CANNOT MOVE
- CONDUCTOR:
a substance with LOW electrical resistance; material that moves the freely moving (+) & (-) charges
neural regeneration
- ## has the LIMITED ABILITY TO RECOVER; they are AMITIOIC (cannot be replaced b/c neurons do not undergo mitosis/ or due to lack of centrosomes)
- Distal axons DEGENERATE & are PHAGOCYTOSED
- MULTIPLICATION of SCHWANN CELLS - the creation of CELLULAR CORD
- RELEASE of GROWTH FACTOR from SCHWANN CELL (helps the axon regrow to the original path)
*not guaranteed growth
