Nervous tissue

Question 1

overview of nervous system:

Answer 1

network of specialised cells for communication btw host and environment

• regulates body functions
• maintains homeostasis (helped by endocrine system)
• responsible for all behaviours, memories, movement

Question 2

list basic functions:

Answer 2

sensory, integrative, motor

Question 3

sensory:

Answer 3

sense changes in internal/external environments through sensory receptors
- sensory (afferent) neurons

Question 4

integrative:

Answer 4

process/ store sensory info, make decisions regarding appropriate responses
- association/ interneurons

Question 5

motor:

Answer 5

responds to stimuli by initiating action

- motor (efferent) neurons

Question 6

list parts of CNS

Answer 6

central nervous system:

• brain
• spinal cord

Question 7

list parts of PNS

Answer 7

peripheral nervous system:

• cranial nerves
• spinal nerves
• ganglia
• plexuses
• receptors

Question 8

3 types of PNS

Answer 8

• somatic nervous system
• autonomic nervous system
• enteric nervous system

Question 9

list two categories of cells in nervous system:

Answer 9

neurons, neuroglia (glial cells)

Question 10

general features/ function: neurons

Answer 10

functional unit of nervous sytem

• propagates electrical impulses
• 3 main types: multipolar, bipolar, unipolar

Question 11

features/ function: neuroglia

Answer 11

supportive cells
- 6 major types
(4 in CNS, 2 in PNS)

Question 12

main parts of neurons:

Answer 12

dendrites (afferent)
cell body (integration)
axon (efferent)

Question 13

features/ function: dendrites

Answer 13

RECEIVING signals from other neurons (less: intergrating)

• typically many dendrites with numerous branches
• diameter tapers away from cell body
• not myelinated
• passively conduct graded potentials from synapses -> towards cell body

Question 14

features/ function: cell body

Answer 14

soma or perikaryon

• variable in size/ shape
• INTERGRATING signals
• cytoplasm has many organelles

Question 15

organelles of cell body:

Answer 15

nucleus, nissl bodies (ER), golgi apparatus, mitochondria, microtubules

Question 16

features/ function: axons

Answer 16

PROPAGATING signals from neuron-neuron

• 1 axon per neuron, relatively few branches (exc. near terminal end)
• uniform diameter entire way
• often myelinated, increase conduction velocity
• propagates action potentials away -> cell body toward -> synapses at axon terminal

Question 17

features/ function: synapse

Answer 17

junction btw two neurons/ neuron and effector organ

• electrical
• chemical

postsynaptic potentials in other neuron/ organ:

• excitatory
• inhibitory

Question 18

list different classifications of neurons: and why?

Answer 18

based on no. of structures directly attached to cell body:
unipolar
bipolar
multipolar

Question 19

features: multipolar neuron

Answer 19

most common

• cell body btw many dendrites
• axon

Question 20

features: bipolar neuron

Answer 20

• cell body middle

- dendrite, axon

Question 21

features: unipolar neuron

Answer 21

sensory neuron

- one structure (axon)

Question 22

trigger zone:

Answer 22

needs to be activated from multiple dendrites of same signal to then pass stronger signal down axon

Question 23

list glial cells in PNS:

Answer 23

schwann cells
satellite cells

similar functions to glial cells in CNS

Question 24

list glial cells in CNS

Answer 24

oligodendrocytes
astrocytes
microglia
ependymal cells

similar functions to glial cells in PNS

Question 25

features/ function: Oligodendrocytes

Answer 25

found in CNS - produces myelin - 1 cell has many processes, wraps myelin around multiple axons

Question 26

features/ function: Schwann cells

Answer 26

found in PNS - produces myelin - 1 cell forms myelin around 1 segment of 1 axon

Question 27

features/ function: myelin

Answer 27

80% lipid, 20% protein - electrical insulation of axon - increases velocity of impulse propagation - larger diameter axons have thicker/ more effective myelin sheaths (up to 100s of layers) - provides track for regrowth to occur

Question 28

features/ function: astrocytes

Answer 28

found in CNS - most abundant cell in CNS - structural/ metabolic support - maintains extracellular chemical balance - principal role in nervous system repair

Question 29

features/ function: satellite cells

Answer 29

found in PNS - flattened cells surrounding neuron cell bodies within ganglia - similar role to astrocytes (metabolic/ structural support) aka: mantle cells, amphicytes

Question 30

features/ function: ependymal cells

Answer 30

found in CNS - lines ventricles of brain/ central canal of spinal cord - columnar/ cuboidal epithelium - ependymocytes: in choroid plexuses produce CSF - ciliated ependymocytes: help circulate CSF

Question 31

features/ function: microglia

Answer 31

found in CNS - from precursor cells in bone marrow (monocyte) - similar to macrophages elsewhere in body main active immune defence in the CNS: - scavenging - phagocytosis - cytotoxicity - antigen presentation - promotes repair

Question 32

list layers of cerebral cortex:

Answer 32

``` I: molecular layer II: outer granular layer III: outer pyramidal layer IV: inner granular layer V: inner pyramidal layer VI: layer of pleiomorphic cells ```

Question 33

distinguish layers: cerebral cortex

Answer 33

no boundaries, hard to distinguish

Question 34

list layers of cerebellar cortex:

Answer 34

I: molecular layer II: Purkinje cell layer III: granular cell layer

Question 35

list connective tissue associated with peripheral nerves:

Answer 35

endoneurium, perineurium, epineurium

Question 36

endoneurium:

Answer 36

surrounds each axon

Question 37

perineurium:

Answer 37

forms complete sleeve around bundle of axons

Question 38

epineurium:

Answer 38

dense sheath covering entire peripheral nerve

Question 39

features in molecular layer (cerebral cortex):

Answer 39

contains relatively few nerve cell bodies | - composed largely of dendrites, axon terminals, neuroglia

Question 40

features in outer granular layer (cerebral cortex):

Answer 40

typically contains very small cells (granule cells)

Question 41

features in outer pyramidal layer:

Answer 41

contains cell bodies of small pyramidal cells

Question 42

features in inner granular layer (cerebral cortex):

Answer 42

-

Question 43

features in inner pyramidal layer:

Answer 43

contains cell bodies of large pyramidal cells

Question 44

features in layer of pleiomorphic cells:

Answer 44

contains cells of assorted size and shape

Question 45

features in molecular layer (cerebellar cortex):

Answer 45

dendrites of Purkinje cells, axons of granule cells, neuroglia

Question 46

features in Purkinje cell layer:

Answer 46

-

Question 47

features in granular cell layer (cerebellar cortex):

Answer 47

packed with nuclei of many cerebellar granule cells