Nervous Tissue

Question 1

the nervous system

Answer 1

• 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

Question 2

how is the nervous system organized?

Answer 2

composed of two parts; the CNS (central nervous system) & PNS (peripheral nervous system)

Question 3

central nervous system

Answer 3

• consists of the BRAIN & SPINAL CORD
• helps with integration, processing, coordinating info, and higher brain functions

Question 4

peripheral nervous system

Answer 4

• variation of NERVES + other NEURAL TISSUE outside of the CNS
• has two functional divisions:
  the AFFERENT (SENSORY) DIVISION & the EFFERENT (MOTOR) DIVISION

Question 5

types of inputs/information

Answer 5

1. 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]

2. MOTOR OUTPUT:
   - activator becomes active and CREATION OF “WORK” in RESPONSE (EFFERENT DIVISION)
   ex. muscle, joint, or hormone

Question 6

sensory (afferent) division of the PNS

Answer 6

brings sensory info to the CNS from receptors through the body
- also has TWO DIVISIONS:

1. SOMATIC SENSORY DIVISION/FIBERS:
   - sensory info from muscles, joints, and special senses, to the CNS
2. VISCERAL SENSORY DIVISION/FIBERS:
   - sensory info from VISCERAL ORGANS to CNS
   (smooth/cardiac muscle, digestive organs, etc…)

Question 7

somatic nervous system [motor division]

Answer 7

• 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)

Question 7

motor (efferent) division of the PNS

Answer 7

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

Question 8

autonomic nervous system [motor division]

Answer 8

• 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

Question 9

cells of the nervous system

Answer 9

1. NEUROGLIA/GLIAL CELLS
   - helps with support, regulation, and protection of neurons
2. NEURONS (NERVE CELLS)
   - helps conduct ELECTRICAL SIGNALS
   - aid in PROCESSING, TRANSFER, & STORAGE OF INFO

Question 10

what are the CNS glial cells?

Answer 10

• astrocytes
• oligodendrocytes
• microglia
• ependymal cells

Question 11

what are the PNS glial cells?

Answer 11

• schwann cells (neurolemmocytes)
• satellite cells

Question 12

astrocytes

Answer 12

• 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)

Question 13

oligodendrocytes

Answer 13

• 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)

Question 14

microglia

Answer 14

• 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

Question 15

ependymal cells

Answer 15

• 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

Question 16

schwann cells

Answer 16

• helps form the MYELIN SHEATH in the PNS
• surrounds the PERIPHERAL AXONS
  helps with NERVE FUNCTION RECOVERY
  (the oligodendrocytes of the PNS)

Question 17

satellite cells

Answer 17

• helps with the PROTECTION OF NEURON CELL BODIES
• helps with REGULATION OF EXCHANGING of MATERIAL between neurons

Question 18

neuron anatomy/structure

Answer 18

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)

Question 19

neuron cell body

Answer 19

• 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

Question 20

myelin sheaths

Answer 20

• 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)

Question 21

structural classification of neurons

Answer 21

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

Question 22

demyelination disorders

Answer 22

disorders or diseases that can destroy myelin/myelinated axons within the CNS or PNS

Question 23

multiple sclerosis

Answer 23

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

Question 24

heavy metal poisoning

Answer 24

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

Question 25

describe the electrical signaling of the membrane potentials

Answer 25

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

Question 26

what are the principles of electricity?

Answer 26

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

Question 27

how are insulators & conductors related to electricity?

Answer 27

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

Question 28

neural regeneration

Answer 28

- 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) -------------------------------------------------------------------- 1. Distal axons DEGENERATE & are PHAGOCYTOSED 2. MULTIPLICATION of SCHWANN CELLS - the creation of CELLULAR CORD 3. RELEASE of GROWTH FACTOR from SCHWANN CELL (helps the axon regrow to the original path) *not guaranteed growth