development and organization of the nervous system (1.3) Flashcards
subdivisions of peripheral (AUTONOMIC) nervous system (2)
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)
zygote
a single cell formed by the amalgamation do an ovum and sperm; divides from two daughter cells until a mature organism is produced
phases of neurodevelopment (5)
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))
germinal stage
the time from fertilization to implantation in the uterus (8 to 10 days); end of stage (“baby in a compact disc”)
germinal stage potency (4)
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
gastrulation (4)
(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
neurulation (definition, neural tube, inside tube, neural crest, somite)
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)
neural proliferation
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
neural migration and aggregation (neural stem cells, radial and tangential migration)
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
axon growth and synapse formation (growth cone and filopodia)
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)
directional terms (8)
anterior/rostral: front/nose
posterior/caudal: back/tail
dorsal/superior: too
ventral/inferior: bottom
medial: middle
lateral: side
proximal: close
distal: far
ipsilateral vs contralateral
ipsilateral: same side
contralateral: opposite side
planes (4)
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)
lateral view of the brain (cerebrum, cerebellum, brain stem)
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)
spinal cord, dorsal and ventral roots
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)
two areas comprised by the spinal cord in cross section (inner H-shaped core of gray matter, outer area of white matter)
gray matter: (cell bodies and unmyelinated interneurons) organized into sensory (dorsal) and motor (ventral) nuclei
white matter: myelinated axons
separate the nervous system from the bone right outside (3)
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
cerebrospinal fluid (CSF)
fills the subarachnoid space covering the brain and spinal cord; supports the CNS and provides cushioning against injury
blood barriers
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
somatic vs autonomic nervous system (PNS)
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)
cranial nerves
considered to be part of the PNS, primarily stimulating the head and neck
