the CNS Flashcards
what does gray matter consist mostly of?
unmyelinated axons, with somas and dendrites
what does white matter consist of?
mostly myelinated axons, no somas or dendrites
where is cerebral spinal fluid contained?
in the space between the arachnoid membrane and pia mater (the subarachnoid space)
what are the meninges and what do they do?
three layers that protect the brain and spinal cord–pia mater, arachnoid membrane, dura mater
the spinal cord is the major pathway for information flowing back and forth between the brain, skin, muscles, and joints of the body
ya
how many cervical segments are there?
8
how many thoracic segments are there?
12
how many lumbar segments are there?
5
how many sacral segments are there?
5
how many coccygeal segments are there?
1
what is the role of the dorsal root?
carries afferent info from the periphery, through spinal cord, up to brain
what is the role of the ventral root?
carries efferent info from brain, down spinal cord, to periphery
white matter contains tracts of axons carrying info to and from the brain
ya
what is a spinal reflex?
a response created by the spine without input from the brain–particularly important in body movement
brainstem contains 11 of 12 cranial nerves (except the olfactory one) as it leads straight into the thalamus–where olfactory nerve just goes to olfactory cortex
ya
what are the processes with which the brainstem is involved?
sleep and arousal, muscle tone and stretch reflexes, coordination of breathing, blood pressure and modulation of pain
white matter of the medulla contains all of the ascending somatosensory tracts and descending corticospinal tracts
ya
90% of all corticospinal tracts decussate/crossover at the pyramids
ya
nuclei in the medulla contain the cardio centre and medulla resp centre–linked together–>changes in blood flow means you need changes in resp
ya
what centres does the medulla contain?
cardio and medulla resp centre; vomiting centre; sneezing/coughing/hicupping centre; swallowing or deglutition centre
what does the pons contain?
nuclei and tracts
what is the purpose of the pons?
relay info between the cerebrum and cerebellum and to assist the medulla in the coordination of breathing
function of the midbrain
control of eye movement, relays auditory and visual reflexes (movement of body in response to these stimuli) and contains the substantia nigra which plays a role in reward (dopaminergic) and movement
midbrain is the junction bw the lower brainstem and the diencephalon (nuclei and tracts)
ya
what is reticular formation?
extends throughout the brainstem–small neuronal cell bodies interspersed among tracts (ascending and descending)
what is reticular formation important in?
conciousness, arousal, attention, alertness; involved in the reticular activating system (RAS)?
what is the purpose of ras?
sends sensory info to cortex and filters info so you’re not overloaded; RAS inactivated during sleep–>damage to RAS can lead to coma; regulates muscle tone, assists in vital functions
what is the purpose of the cerebellum?
processes sensory info and coordinates the execution of movement; alters movement as it occurs; regulates posture and balance; sends feedback signals to motor areas of the cerebral cortex, via its connections to the thalamus helping to correct any errors and smooth the movements
what is the diencephalon composed of?
two primary structures: thalamus and hypothalamus; and two endocrine structure: pineal gland and pituitary gland
what is the role of the thalamus?
relay centre–recieves sensory info from the optic tracts, ears, spinal cord, and motor info from cereellum and projects info to cerebrum for processing
what is the role of the pineal gland?
cyclically releases melatonin and is involved in the sleep/wake cycle
functions of the hypothalamus?
centre for homeostasis-influences autonomic and endocrine function;
- activates symp NS: controls catecholamine release from adrenal medulla (important for flight or fight rxn); maintains BGL via endocrine pancreas;
- maintains body temp–stimulates shivering and sweating
- controls body osmolarity–motivates thirst and drinking; stimulates secretion of vasopressin
- controls repro functions–directs secreton of oxytocin (not homeostatic)–for milk production and uterine contractions; directs tropic hormone control of ant pit hormones–FSH and LH
- controls food intake–stimualtes satiety centre and feeding centre
- interacts with limbic system to influence behaviour and emotion
- influences cardi cntrol centre in medulla oblongata
- secretes tropic hormones that control release of hormones from ant pit
Function of pit gland?
output for hypothalamus
describe the structure of the pit gland
connected to the hypothalamus by a long stalk called the infundibulum; the post pit is an extension of neural tissue while the ant pit is an endocrine gland; protected by the sphenoid bone
types of neurons in neurohypophysis
one contains oxytocin which stilumates milk production and urinary contraction; the other contains vasopressin which stimulates water reabsoprtion from kidneys
describe release of hormones in ant pit
neurons from hypothal release trophic hormones which are carried by capillary beds (hypothalamic-hypophyseal portal system) to the ant pit where they stimulate the release of peptide hormones
what does the gray matter in the cerebrum contain?
cerebral cortex, basal ganglia, limbic system
cerebrum is the area of higher processing–separated into 2 distinct lobes connected by the corpus callosum
ya
what is the basal ganglia/nuclei and what is its role?
three nuclei collectively termed basal ganglia–globus pallidus, putamen, caudate nucleus; receives input from cerebral cortex and provides output to motor portions of the cortex; major job is to regulate and coordinate the initiation and termination of movement
limbic system role
primary role in emotions including pain, pleasrure, docility, affection, and anger; may play a major role in learning and memory
major components of limbic system and their roles
cingulate gyrus–produces emotion; amygdala–emotion, some learning and memory; hippocampus–has a major role in learning and memory by creating new neurons
cerebral cortex is the outermost layer of the cerebrum and is the integrating centre for the CNS
ya
what are sulci and gyri?
sulci–indentations in the brain tissue; gyri–protrustions created by two indentations
specializations of the cerebral cortex
- sensory areas–translate sensory input into perceptions
- motor areas–direct skeletal muscle movement
- association areas–integrate into from sensory nd motor areas and helps direct voluntary behaviours
cerebral cortex can undergo plasticity–if you lose your hand, that part responsible for your hand will move to another part of the body (e.g. leg)
ya
what are receptor/generator potentials?
graded potentials in sensory neurons
