Nervous Sytem: Organisation

Question 1

Name the 5 major parts of CNS and their functions

Answer 1

1. Cerebrum: Higher cognition 2. Cerebellum: Motor coordination 3. Brainstem: Vital reflexes 4. Spinal cord: Signal conduction 5. Retina: Light detection

Question 2

List the 3 main functions of nervous system

Answer 2

1. Sensory input 2. Integration 3. Motor output

Question 3

Name 6 types of glial cells and their functions

Answer 3

1. Astrocytes: BBB maintenance 2. Oligodendrocytes: CNS myelination 3. Microglia: Immune defense 4. Ependymal: CSF production 5. Schwann cells: PNS myelination 6. Satellite cells: PNS support

Question 4

Describe neuron structure

Answer 4

1. Cell body (nucleus/organelles) 2. Dendrites (input) 3. Axon (output) 4. Synaptic terminals (neurotransmitter release)

Question 5

Classify neurons by structure

Answer 5

1. Multipolar (motor neurons) 2. Bipolar (retina) 3. Pseudounipolar (DRG sensory)

Question 6

Classify neurons by function

Answer 6

1. Sensory (afferent) 2. Motor (efferent) 3. Interneurons (CNS integration)

Question 7

What is the role of astrocytes?

Answer 7

1. Maintain BBB 2. Regulate ions/neurotransmitters 3. Support synaptic plasticity

Question 8

How do oligodendrocytes differ from Schwann cells?

Answer 8

Oligodendrocytes: CNS, myelinate multiple axons. Schwann: PNS, myelinate 1 axon segment

Question 9

What is the function of microglia?

Answer 9

CNS macrophages → phagocytose pathogens/debris (activated in neuroinflammation)

Question 10

Describe myelination in PNS

Answer 10

Schwann cells wrap around axons → form nodes of Ranvier → saltatory conduction

Question 11

Name the 4 functional zones of a neuron

Answer 11

1. Input (dendrites) 2. Integration (axon hillock) 3. Conduction (axon) 4. Output (synapse)

Question 12

What are Nissl bodies?

Answer 12

RER in neuron cell bodies → protein synthesis (stain basophilic)

Question 13

How are neurons classified by axon length?

Answer 13

1. Golgi I (long axons) 2. Golgi II (short axons)

Question 14

What makes white matter white?

Answer 14

High lipid content in myelin sheaths (oligodendrocytes/Schwann cells)

Question 15

What are the 3 meningeal layers?

Answer 15

1. Dura mater 2. Arachnoid 3. Pia mater (from outer to inner)

Question 16

What is sensation?

Answer 16

Basic recognition of environmental stimuli through detectable changes in physical energy.

Question 17

What are the 3 key steps in sensory processing?

Answer 17

1. Stimulus detection 2. Transduction by receptors 3. Transmission to CNS

Question 18

How do receptors convert stimuli to neural signals?

Answer 18

Transduction: Environmental energy (e.g., light, pressure) → Action potentials via specialized receptors.

Question 19

Name 6 stimulus modalities detected by receptors

Answer 19

1. Mechanical 2. Chemical 3. Photic (light) 4. Auditory 5. Thermal 6. Electrical

Question 20

What is the role of sensory neurons?

Answer 20

Transmit action potentials from receptors → CNS via sensory pathways.

Question 21

Where does sensory transduction occur?

Answer 21

At receptor endings (e.g., Pacinian corpuscle for pressure, rods/cones for light).

Question 22

How is stimulus intensity encoded?

Answer 22

1. Frequency of action potentials 2. Number of activated receptors (population coding).

Question 23

What determines stimulus modality?

Answer 23

Labeled line coding: Specific receptor types → Dedicated CNS pathways (e.g., photoreceptors → visual cortex).

Question 24

What is adaptation in sensory receptors?

Answer 24

Decreased response to constant stimuli (phasic receptors adapt fast, tonic receptors adapt slowly).

Question 25

Compare phasic vs. tonic receptors

Answer 25

Phasic: Detect changes (e.g., Pacinian corpuscle). Tonic: Continuous monitoring (e.g., muscle spindle).

Question 26

What are first-order sensory neurons?

Answer 26

Afferent neurons with cell bodies in DRG (PNS) that directly innervate receptors.

Question 27

What is the difference between general and special senses?

Answer 27

General: Widespread (touch, pain). Special: Localized organs (vision, taste, hearing).

Question 28

How does the CNS distinguish stimulus location?

Answer 28

Receptive field mapping: Specific body areas → Corresponding CNS regions (e.g., somatotopy).