Nervous Tissue

Question 1

Ganglia

Answer 1

Neuronal cell bodies in the PNS

Question 2

Afferent

Answer 2

toward CNS- sensory

Question 3

Efferent

Answer 3

away from CNS- Motor

Question 4

NissI Bodies (chromatophilic bodies)

Answer 4

clusters of rought ER and free ribosomes

Question 5

Neurofibrils

Answer 5

intermediate filament bundles, make a network between nissI bodies and preven cell from being pulled apart

Question 6

neurofilaments

Answer 6

in axon. with action and mictorubles, provide structural strength. aids in axonal transport

Question 7

Multipolar Nerves

Answer 7

more than 2 processes
~99% of all nerves
multiple dendrites, 1 axon
interneurons and motor neurons are multipolar

Question 8

Bipolar nerves

Answer 8

2 processes that extend from opposite sides of the cell body
one process is a fused dendrite, the other is the axon.
rare
found in some special sensory organs: inner ear, olfactory epithelium, retina

Question 9

Unipolar Nerves

Answer 9

one short single process near neuron cell body. It then divides into 2 long processes.
One long branch goes the to CNS (central process), the other one goes to periphery receptors (dendritic process)
Found in some sensory ganglia of the PNS.
Common in dorsal root ganglia of cranial nerves

Question 10

Neuron Characteristics

Answer 10

longevity
no mitotic division
high metabolic rate

Question 11

Neuroglial Cells- Astrocytes

Answer 11

CNS
most common.
Radiating processes with bulbous ends cling to neurons/capillaries.
extract blood sugar for energy
sense neurotransmitter release. Regulate neurotransmitter levels by increasing uptake in regions of high activity. They also signal to sincrease blood flow in these regions
-take up and release ions to influence ionic environment
-produce molecules neccessary for neural developement ex: brain derived trophic factor.
propagate Ca2+ signals that may be involved in memory

Question 12

Neuroglial CellsEpendymal Cells

Answer 12

CNS
simple epithelium that lines the central cavity of the spinal cord and brain. Fairly permeable. Between cerebral spinal fluid and tissue fluid that baths the cells of the CNS.
Have cilia that help circulate CSF

Question 13

Neuroglial Cells-Microglial cells

Answer 13

CNS
Defense.
-Smallest, least abundant
-elongated with many cell processes that have pointed projections
-phagocytes (dead neurons)
-support maturation of synaptic cleft
- do NOT originate from nervous tissue– derived from monocytes.

Question 14

Neuroglial Cells- oligodendrocytes

Answer 14

CNS
Have fewer branches than astocytes. Wrap their cell processes around thicker axons. Produce MYELIN sheath. Multiple processes from one oligodendrocyte can myelinate multiple axons.
make nodes of ranvier

Question 15

Neuroglial Cells- satelite cells

Answer 15

PNS

surround cell bodies

Question 16

Neuroglial Cells- Schwann Cells

Answer 16

PNS
make myelin sheath in PNS axons by wrapping around them in concentric rings. This causes the cytoplasm to get pushed toward the outer layer– called the neurollema.
These develop during the fetal period and into the first year of life.

Question 17

Thin PNS axons

Answer 17

unmyelinated. Schwann cells can be around the axon but they dont form concentric rings. Found in ANS and sensory fiber.

Question 18

Nerves- Endoneurium

Answer 18

layer of delicate CT covering schwann cells

Question 19

Nerves- nerve fasicles

Answer 19

groups of axons bound in bundles by CT wrapping (Perineurium)

Question 20

Nerves- perineurium

Answer 20

CT wrapped around nerve fasicle

Question 21

Nerves- epinerium

Answer 21

though fibourous sheath that surround the entire nerve.

Question 22

Gray Matter

Answer 22

surround hollow central cavities. Where neuron cell BODIES cluster.

Question 23

White Matter

Answer 23

no cell bodies. predominantly myelinated axons.

Question 24

Tracts

Answer 24

bundles of axons passing between specific regions of the CNS. Most of these only go between brain and spinal cord.

Question 25

Reflex Arcs

Answer 25

chain of neurons responsible for reflexes. Can be somatic (skeletal muscle) or visceral. Made up of 5 components:

1. receptor
2. sensory neuron
3. integration center
4. motor neuron
5. effector

Question 26

Reflex Arcs- receptor

Answer 26

at terminal end of sensory nerve. Site where stimulus acts

Question 27

Reflex Arcs- Senesory Neuron

Answer 27

transmits afferent impulses to the CNS

Question 28

Reflex Arcs- Integration Center

Answer 28

consists of one or more synapses in the gray matter of the CNS

Question 29

Reflex Arcs- motor neuron

Answer 29

conducts efferent impluse form the integration center to an effector

Question 30

Reflex Arcs- effector

Answer 30

muscle or gland cell that responds to the efferent impulses by contracting or secreting.

Question 31

Monosynaptic Reflex

Answer 31

1 synapse- no interneuron
fast
reflexes that help maintain equilibrium and upright posture ex. knee jerk

Question 32

Polysynaptic reflexes

Answer 32

more common
multiple interneurons
most simple ones have 1 interneuron
es. withdrawl reflex

Question 33

Neruonal Circuits- diverging

Answer 33

diverts into multiple paths.
one pre synaptic neuron synapses with multiple neurons
ex. muscle stretch

Question 34

Neruonal Circuits- Convergent

Answer 34

many synpases–> 1 postsynaptic neuron. may get both excitatory and inhibatory

Question 35

Neruonal Circuits- Reverberating

Answer 35

one neuron recieves feedback from another in the same circuit. Ex. Breathing

Question 36

Serial Processing

Answer 36

pass of a signal to a specific destination in sequence along a single pathway. ex: reflex arc

Question 37

Parallel processing

Answer 37

simultaneously, nerve impulses travel in an axon branch that extends into the spinal white matter and extends as an ascending pathway to the brain. A single stimulus–> multiple perceptions. Ex: withdrawal reflex– pain triggers sensory neuron with initiates spinal withdrawal reflex