Chapter 8: Basic Structure/Function of CNS/PNS

Question 1

Discuss the embryonic development of the nervous system

Answer 1

• Neural tube forms from ECTODERM and becomes CNS
• Swellings from Neural tube become forebrain, midbrain, hindbrain
• Forebrain elaborates into telencephalon and diencephalon
• Midbrain does not subdivide
• Hind brain forms mesencephalon and myelencephalon
• Neural crest cells develop where tube fuses and becomes ganglia of PNS

Question 2

Discuss the cerebrum.

Answer 2

• largest part of the brain
• higher mental functions
• Right and left hemispheres connected by corpus callosum

Question 3

Discuss the cerebral cortex.

Answer 3

• Has gyri (gyrus): elevated folds
  
  • precentral gyrus: motor control involvement
  • postcentral gyrus: receives sensory info
• Has sulci (sulcus): depressed groove
• 5 Lobes:
  1. Frontal Lobe
  2. Parietal Lobe
  3. Temporal Lobe
  4. Occipital Lobe
  5. Insular Lobe

Question 4

Briefly discuss the functions of each of the (5) lobes.

Answer 4

1. Frontal Lobe
   - Voluntary motor control, personality, verbal communication, higher processing (like decision making and planning)
2. Parietal Lobe
   - Understand speech, formation of words to express thoughts/emotions, interpretation of texture/shapes
3. Temporal Lobe
   - Interpretation of auditory sensations
4. Occipital Lobe
   - vision (perception of images, eye movement, etc)
5. Insular Lobe
   - Memory, sensory and visceral integration

Question 5

Briefly discuss basal nuclei.

Answer 5

• Function in control of voluntary movement

- Creates motor circuit that stimulates appropriate movements and inhibits unwanted movement

Question 6

Discuss cerebral lateralization.

Answer 6

• It’s the specialization of each hemisphere for certain functions
• Each hemisphere controls movement on the opposite side of the body
• Hemispheres communicate via corpus callosum
• Some tasks are performed better on one side of the brain than the other:
  
  • Left hemisphere: Science/Math; speech, writing, analytical
  • Right hemisphere: Artistic side; visual/spatial tasks, recognizing faces, composing music

Question 7

What do Wernicke’s area and Broca’s area do?

How are they related to one another?

Answer 7

Wernicke’s: Language comprehension (understanding words)
- aphasia here results in “word salad” (rapid speech with no meaning)

Broca’s: Motor control for speech

• aphasia here results in slow, poorly articulated speech but no impairment of understanding (only production of speech is impaired)
• pt could easily write down what they’re trying to say

To speak word comprehension originates in Wernicke’s and is sent to Broca’s
Broca’s sends info to motor cortex to direct movement of appropriate muscles for speech

Question 8

Discuss the limbic system.

Answer 8

Limbic system and hypothalamus are crucial for aggression and emotional response

• including fear, feeding, sex, and goal-related behavior (emotional drives)
• Amygdala: fear memory and emotional content

Question 9

Discuss memory.

Answer 9

• Short term and long term
• 2 types of long term:
  1. Non-declaritive (explicit): memory of simple skills (how to do things like tie shoes)
  2. Declaritive (implicit): memories that can bet verbalized (facts, events)
  
  • this is impaired in amnesiacs;
  • i.e., they can tie their shoes but they can’t tell you how to do it.
• Hippocampus: acquires new memories and consolidates them into short- or long-term memory
• Amygdala: fear memory and emotional content
• Working memory: involves prefrontal cortex

Question 10

Discuss the Hippocampus and neurogenesis.

Answer 10

• crucial for learning and memory
• hippocampus contains neural stem cells that continually produce new neurons (neurogenesis)
• stress or depression impede learning and cause hippocampus to shrink
• age and stress reduce neurogenesis

Question 11

Discuss the thalamus and epithalamus.

Answer 11

Thalamus: relay center for all sensory info to pass through to the cerebrum (except smell)

Epithalamus: contains choroid plexus that secretes CSF; pineal gland here secretes melatonin that helps with sleep cycle

Question 12

Discuss the hypothalamus.

Answer 12

Important for maintaining homeostasis and regulating ANS

• Coordinates symp and parasymp actions
• Regulates body temp, sleep and wakefulness
• Controls endocrine system/hormone release from ant. pituitary gland
• Centers for hunger/satiety and thirst, sexual arousal/performance, emotions - fear, anger, pain, pleasure
• Produces ADH and oxytocin

Question 13

Discuss the midbrain.

Answer 13

Superior colliculi: visual reflexes
Inferior colliculi: relay auditory info

*Red nucleus: connects cerebrum and cerebellum; involved in motor coordination

Substantia nigra: motor circuit; dopamine neurons

Question 14

Discuss the 3 portions of the hindbrain:
Pons
Medulla oblongata
Cerebellum

Answer 14

Pons
- 2 important respiratory control centers

Medulla oblongata

• contains all tracts that pass between brain and spinal cord
• Several crucial centers for breathing and cardiovascular systems

Cerebellum

• Gets input from proprioceptors and is involved in coordination, movements, and motor learning
• Involved in timing and grading movements

Question 15

Discuss the PNS.

Answer 15

• nerves that exit from the CNS and their ganglia (collection of neuron cells bodies outside the CNS)
• 12 pairs of cranial nerves; most mix of sensory and motor fibers

Question 16

Discuss spinal nerves.

Answer 16

• Dorsal root: posterior, sensory fibers
• Ventral root: anterior, motor fibers
• 31 pairs:
  
  • 8 Cervical
  • 12 Thoracic
  • 5 Lumbar
  • 5 Sacral
  • 1 Coccygeal
• C1-C7 - come out ABOVE vertebra
• C8-Down - come out below vertebra

Question 17

Discuss the reflex arc.

Answer 17

Simple circuit of sensory input in, motor input out.
Involves peripheral nerves and spinal nerves
Some have interneuron in between