development and organization of the nervous system (1.3)

Question 1

subdivisions of peripheral (AUTONOMIC) nervous system (2)

Answer 1

sympathetic: fight or flight; arousal (automatic motor nerves that project from the cns in the spinal cord and stimulate, organize, and mobilize energy resources in threatening situations)
parasympathetic: calming down; psychological relaxation (automatic motor nerves that project from the brain and lower spinal cord and conserve energy)

Question 2

zygote

Answer 2

a single cell formed by the amalgamation do an ovum and sperm; divides from two daughter cells until a mature organism is produced

Question 3

phases of neurodevelopment (5)

Answer 3

induction of neural plate: neural plate (patch of ectodermal tissue on dorsal surface of embryo) folds to form the neural groove which then forms the neural tube
neural proliferation: cells of tube begun to proliferate (increase greatly in number)
migration and aggregation: immature cells migrate to appropriate target location; developing neurons align themselves with other developing neurons that migrated to the same area (aggregation)
axon growth/synapse formation: axons must establish appropriate pattern of synapses (requires coordinated activity)
synapse refinement: more focused pattern of synaptic contact (neuron death due to lack of neurotrophins; neural activity (fire together, wire together))

Question 4

germinal stage

Answer 4

the time from fertilization to implantation in the uterus (8 to 10 days); end of stage (“baby in a compact disc”)

Question 5

germinal stage potency (4)

Answer 5

potency: the ability to develop into different cell types
totipotent: become anything that he needed to produce a viable pregnancy (morula^)
pluripotent: can develop into many but not all classes of body cells (embryonic stem cells; blastocyst^)
multipotent: new cells can develop into different cells if only one class (i.e. different blood cells)
unipotent: cells can develop into only one type of cell

Question 6

gastrulation (4)

Answer 6

(1) cells of inner cell mass begin to differentiate as amnion forms
(2) gastrula develops when cells begin to migrate inward (forms indentation)
(3) cells continue to push inward (form endoderm); cells on outer surface of gastrula are called ectoderm
(4) mesoderm is formed (middle layer) as additional cells migrate inward between endoderm and ectoderm

Question 7

neurulation (definition, neural tube, inside tube, neural crest, somite)

Answer 7

definition: the stage at which the nervous system emerges
neural tube: formed when edges of ectoderm elevate and meet at the mid-line (precursor to CNS)
inside tube: fluid-filled cavities in the brain (ventricles) and spinal cord (canal)
neural crest: in PNS; dorsal to neural tube; formed from cells that break off from neural tube as it forms
somite: future skull and vertebrae (spine)

Question 8

neural proliferation

Answer 8

neural tube changes it’s size and shape (morphology) where the head later forms the brain and the tail later forms the spinal cord; first three swellings (forebrain, midbrain, hindbrain) then five swellings (forebrain —> telencephalon and diencephalon, midbrain —> mesencephalon, hindbrain —> metencephalon and myelencsphalon); brain stem formed by lower four divisions

Question 9

neural migration and aggregation (neural stem cells, radial and tangential migration)

Answer 9

neural stem cells (radial glial cells): generated at inner surface of neural tube and migrate to form structures
radial: neural stem cells move up at the edge (straight line outward toward the outer wall of tube)
tangential: cells move around or down the tube before moving up to the edge

Question 10

axon growth and synapse formation (growth cone and filopodia)

Answer 10

growth cone: growing tip of a neurite (axon or dendrite)
filopodia: thin spikes on growth cone that extend and retract in response to guidance molecules (chemoaffinity hypothesis —> specific chemical label)

Question 11

directional terms (8)

Answer 11

anterior/rostral: front/nose
posterior/caudal: back/tail
dorsal/superior: too
ventral/inferior: bottom
medial: middle
lateral: side
proximal: close
distal: far

Question 12

ipsilateral vs contralateral

Answer 12

ipsilateral: same side
contralateral: opposite side

Question 13

planes (4)

Answer 13

sagittal: left vs right (midsagittal separates left and right brain)
horizontal: top vs bottom
frontal (coronal): front vs back
cross-section: right angle to long narrow structure (never in brain)

Question 14

lateral view of the brain (cerebrum, cerebellum, brain stem)

Answer 14

cerebrum: telencephalon; two hemispheres that receive sensory input and control motor output to the opposite side of the body
cerebellum: below cerebrum; motor control center for same side of body
brain stem: fibers of passage, cranial nerves, basic functions (i.e. breath rate)

Question 15

spinal cord, dorsal and ventral roots

Answer 15

spinal cord: a long, thin, tubular bundle of nervous tissue that extends from the brain stem
dorsal root: brings sensory information from the body into the spinal cord (afferent)
ventral root: carries motor commands from the cord to body (efferent)

Question 16

two areas comprised by the spinal cord in cross section (inner H-shaped core of gray matter, outer area of white matter)

Answer 16

gray matter: (cell bodies and unmyelinated interneurons) organized into sensory (dorsal) and motor (ventral) nuclei
white matter: myelinated axons

Question 17

separate the nervous system from the bone right outside (3)

Answer 17

dura mater: “thought mother;” out meninx
arachnoid membrane: inside dura mater; fine, spider-web-like membrane (subarachnoid space beneath membrane that contains many large blood vessels and CSF)
pia mater: “pious mother;” delicate; innermost meninx; adheres to the surface of the CNS

Question 18

cerebrospinal fluid (CSF)

Answer 18

fills the subarachnoid space covering the brain and spinal cord; supports the CNS and provides cushioning against injury

Question 19

blood barriers

Answer 19

in the form of tightly packed endothelial cells lining blood vessel walls; maintain environment by preventing things (foreign substances, proteins/large molecules, highly charged molecules, hormones and neurotransmitters) from going into the CNS; glucose actively transported; weak in some areas to allow for monitoring of the chemical composition of blood

Question 20

somatic vs autonomic nervous system (PNS)

Answer 20

somatic: conscious; sensory and motor stimulation to all body parts except organs, smooth muscles, and glands; sensations we are aware of, along with voluntary movements; interacts with external environment
autonomic: unconscious; regulates the visceral (organ) functions that maintain homeostasis within the body (i.e. heart rate, blood pressure, digestion); internal environment (sympathetic and parasympathetic)

Question 21

cranial nerves

Answer 21

considered to be part of the PNS, primarily stimulating the head and neck