Lecture 1: Organization of the Nervous System

Question 1

What is the function of the nervous system?

Answer 1

• -Detects environmental changes
• -Responds to such events
• -Divided into central nervous system (CNS) & peripheral nervous system (PNS)

Question 2

What is the peripheral nervous system divided into?

Answer 2

somatic nervous system (SNS): Soma means body so somatic nervous system is the voluntary control of skeletal muscles and other body muscles
bilaterally symmetrical just like the central nervous system
–cranial nerves
–spinal nerves

autonomic nervous system (ANS): controls things that you don’t think about and happens automatically (breathing, heart rate, etc)

• -sympathetic divison (arousal)
• -parasympathetic division (calming)

Question 3

What are cranial nerves?

Answer 3

• -part of somatic nervous system
• -12 pairs of nerves that connects the brain and internal organs, influencing autonomic responses
• -These cranial nerves are either only responsible for afferent functions (sensation from eyes/ears/moth/nose), some only for efferent functions (motor control over facial muscles/tongue/eye), and some for both functions

Question 4

What are afferent neurons?

Answer 4

sensory neurons that carry incoming sensory stimuli towards the central nervous system

Question 5

What are efferent neurons?

Answer 5

outgoing motor neurons that carry signals away from the central nervous system

Question 6

What are spinal nerves?

Answer 6

• -part of somatic nervous system
• -have both efferent and afferent functions (functionally equivalent to cranial nerves)
• -dorsal fibers: afferent
• -ventral fibers: efferent
• -collection of fibers entering/exiting spinal cord segment is called a root (dorsal root, ventral root)
• -Control and carry information about the body, trunk & limbs

Question 7

What is the Law of Bell & Magendie?

Answer 7

• -Dorsal spinal cord is sensory (afferent) & ventral side is motor (efferent);
• -Allows inferences about location of spinal-cord damage on the basis of changes in sensation or movement that a patient experiences.

Question 8

What is the sympathetic division?

Answer 8

• -Fight or Flight;
• -Connected to thoracic & lumbar spinal-cord regions;
• -Spinal cord connects to autonomic control center, made up of ganglia.

Question 9

What is the parasympathetic division?

Answer 9

• -Rest & Digest;
• -Connects through cranial nerves: 3, 7 & 10;
• -Also connected to sacral region of spinal cord

Question 10

What is central nervous system made of?

Answer 10

1) Brain

2) Spinal cord

Question 11

What is the spinal cord?

Answer 11

• -part of central nervous system
• -Can act independently of the brain (Automatic movements, hard for the brain to inhibit)
• -Spinal reflex: reflex arc/interneuron

Vertebrae

• -Segments of the spinal cord;
• -Divided into 5 anatomical regions
• -Cervical (C1  C8)
• -Thoracic (T1  T12)
• -Lumbar (L1  L5)
• -Sacral (S1  S5)

Dermatomes

• -Segments of the body/skin;
• -Each dermatome contains sensory nerve & motor nerves (spinal nerves).
• -Each vertebrae is responsible for one dermatome, or one section of skin/body
• -Law of Bell & Magendie allows you to know whether it is a dorsal root or ventral root, and dermatomes allow you to know exactly which vertebrae it is since each vertebrae is responsible for one specific dermatomes so if one part of skin isn’t feeling anything then you know which vertebrae is not functioning

Question 12

What is the meninges made up of?

Answer 12

Dura Mater (L. hard mother)
–Tough, double layered fibrous tissue;
–Encloses brain & spinal cord.
Arachnoid Layer (L. spider layer)
–Thin sheet of delicate connective tissue;
–Follows the brain’s contour (gyri and sulci).
Pia Mater (L. soft mother)
–Moderately tough membrane of connective tissue;
–Clings to brain surface.

Question 13

What is meningitis?

Answer 13

• -Bacterial infection of the meninges which causes inflammation of the meninges
• —>Particularly the pia mater and arachnoid space;
• —>CSF implicated as well
• -causes Intra-Cranial Pressure (ICP)
• -Inflammation causes swelling of the meninges which puts pressure on the brain
• -Leads to drowsiness, delirium, coma
• -the symptoms of meningitis depends on where that pressure is

Question 14

What is dorsal/ventral, medial/lateral, anterior/posterior, rostral/caudal?

Answer 14

dorsal: top, behind
ventral: bottom, front
anterior: front
posterior: back
rostral: beak/front
caudal: tail/back
medial: toward the brains midline
lateral: located toward the side