Central Nervous System Flashcards
Regions + organizations of CNS
Adult brain regions
1. Cerebral hemispheres: cortex, cerebral white matter, basal ganglia
2. Diencephalon: Thalamus, hypothalamus, epithalamus
3. Brain stem: midbrain, pons, medulla
4. Cerebellum
Spinal Cord
Ventricles of brain
- connected to one another and to central canal of spinal cord
- lined by ependymal cells
- contain cerebrospinal fluid
- 2 c-shaed lateral ventricles
- third (line in middle) + fourth ventricles (diamond shape)
Hydrocephalus
Cerebral hemispheres + 5 lobes
Surface markings
- ridges (gyri)
- shallow grooves (sulci)
- deep grooves (fissures)
5 lobes per hemisphere
- frontal
- parietal
- occipital
- temporal
- insula
Cerebral cortex + 3 functional areas
- site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding
3 types of functional areas:
- motor area: control voluntary movement
- sensory area: conscious awareness of sensation
- association areas: integrate diverse info
Motor areas
- Primary somatic motor cortex
- control of skeletal muscles
- pyramidal cells –> pyramidal tracts - premotor cortex
- plans movements, coordinates mov’ts of several groups into complex tasks (musical instrument) - Broca’s area
- motor speech area (left hemisphere)
Sensory Areas
- primary somatosensory cortex: parietal lobe + touch
- association areas: understanding of sense
- visual areas
- auditory areas
- olfactory area - smell
- visceral sensory area - full bladder
- vestibular cortex - equilibrium
Visual areas
Occipital lobe
1. primary visual striate cortex
- extreme posterior tip of occipital lobe
- receives visual info from retinas
- visual association area
- uses past visual experiences to interpret visual stimuli (color, form, movement)
- recognizes faces + familiar objects
Auditory areas
Temporal lobe
1. primary auditory cortex
- temporal lobes
- interprets info from inner ear as pitch, loudness, and location
- Auditory association area
- stores memories of sounds and permits perception of sounds (car brakes, voices)
Prefrontal cortex
Frontal lobe
- most complicated region
- intellect, cognition, recall, personality
- working memory for judgement, reasoning, conscience
- develops slowly in children and depends on feedback from environment socially
- lesions here will cause changes in personality
Lateralization of cortical function
Lateralization: division of labor bw hemispheres
- left hemisphere: controls language, math, logic
- right hemisphere: insight, visual spatial skills, intuition, artistic skills
- left + right communicate via fiber tracts in cerebral white matter
Cerebral white matter
- myelinated fibers + their tracts
- responsible for communication
- commissures: connects 2 hemispheres (corpus callosum)
- association fibers: connect diff parts of same hemisphere
- projection fibers: connect hemispheres w/ lower brain/spinal cord
Basal Nuclei Ganglia
Subcortical nuclei
- help regulate attention + cognition
- regulates intensity of slow/stereotypes movements
- inhibit unnecessary movements
- disorders here cause too much movement like huntingtons disease or too little movement like parkinsons
Diencephalon
3 paired structures
1. thalamus: relay station
2. hypothalamus: homeostasis
3. epithalamus: melatonin
Thalamic function
- gateway to cerebral cortex (relay station)
sorts, edits, and relays info (afferent impulses from all senses) - thalamus = inner room
Hypothalamic function
- Autonomic control center: blood pressure, rate and force of heartbeat, digestive tract motility
- Emotional response (limbic system): perception of pleasure, fear, and rage in biological rhythms and drives
- Fearful person: pounding heart, high blood pressure, sweating, dry mouth
- Also regulated body temp, food intake, water balance, thirst
- connected to pituitary gland
Epithalamus
Part of diencephalon
- pineal gland: secretes melatonin which helps regulate sleep-wake cycles
Brain stem
3 regions
1. Midbrain: substantia nigra (parkinsons disease
- Functionally linked to basal ganglia
- produces neurotransmitter dopamine
- degeneration of these dopamine releasing neurons case parkinsons
- Medulla oblongata: connects to spinal cord
- autonomic reflex centers - unconscious activity
cardiovascular center
- cardiac center = adjusts force + rate of heart contractions
- vasomotor center = adjust blood vessel diameter
Respiratory centers
- generate respiratory rhythm
- control rate + depth of breathing
damage to brain stem, esp medulla will lead to death
- Pons: bridge
Cerebellum
- dorsal to brainstem, inferior to occipital lobe
- subconsciously provides precise timing and patterns of skeletal muscle contraction
- tests: balance, coordination, finger-nose
- learning motor tasks (sports/musical instruments)
Functional Brain systems
Networks of neurons that work together and span wide areas of the brain
limbic system: emotional brain
- hippocampus, amygdala, cingulate gyrus, hypothalamus
reticular formation: wakefulness
Limbic system
Emotional/affective brain
- amygdala: recognizes angry/fearful facial expressions, assesses danger, and elicits the fear response, BODY ALARM SYSTEM
- cingulate gyrus: plays a role in expressing emotions via gestures, mental conflict
- limbic + olfactory connected
- odors recall memories
Emotion + cognition
Limbic system (emotional brain) interacts w/ prefrontal lobes (thinking brain)
- our emotions sometimes override logic and why reason cant stop us from expressing emotions
- hippocampus + amygdala –> play a role in memory
Reticular formation
RAS (reticular activating system)
- sends impulses to the cerebral cortex to keep it conscious and alert
- filters out repetitive and weak stimuli and lets important ones in
- RAS inhibited by sleep centers
- severe injury results in coma
Sleep
- state of partial unconsciousness from which a person can be aroused by stimulation
- environmental monitoring continues (can be aroused –> crying baby; sleepwalkers avoid obstacles
- 2 major sleep types defined by EEG patterns
1. nonrapid eye movement NREM
2. Rapid eye movement REM
Sleep importance
- slow wave sleep (NREM stages 3 + 4) is presumed to be restorative stage
- people deprived of REM sleep become moody + depressed
- sleep deprivation linked to increased heart disease, DM, kidney disease, stroke, HBP
- REM sleep may be a reverse learning process where superfluous info is purged from the brain
- daily sleep requirements decline w/ age
Language
Langauge implementation system
- basal nuclei
- Broca’s area (frontal lobe): expressive speech
- wernickes area (temporal lobe): understanding speech
Corresponding areas on right side are involved w/ nonverbal language components
Memory
encoding, storage, retrieval of info
2 stages of storage
- short term memory: working memory, temporary holding of info, limited to 7/8 pieces of info (telephone #)
- Long term memory: LTM has limitless capacity
STM –> LTM
Factors affecting transfer from STM to LTM
- emotional state: best if alert, motivated, surprised, and aroused (norepinephrine) (teachers/emotional situation)
- rehearsal: repetition + practice
- association: tying new info w/ old memories
- automatic memory subconscious info stored in LTM
Protection of brain
- bone (skull)
- membranes (meninges)
- water cushion (cerebrospinal fluid)
- blood-brain barrier (filters toxins, but not lipid soluble like alcohol)
Meninges
Cover + protects CNS
3 layers
- Dura mater: tough mother, fibrous CT
- arachnoid mater: spider, subarachnoid contains CSF + blood vessels
- pia mater: gentle mother, delicate CT, clings to brain like saran wrap
Meningitis: viral/bacterial inflammation
Cerebrospinal fluid CSF
Functions
- gives buoyancy to CNS organs and floats the brain
- protects CNS from blows + other traumas
- nourishes brain and carries chemical signals
- constant volume, replaced every 8 hours
- choroid plexus: hangs from roof of ventricles, produces CSF
Spinal cord
Location
- begins at foramen magnum
- ends as conus medullaris at L1 vertebra
Functions
- provides 2 way communication to and from the brain
- contains spinal reflex centers
Protected by vertebral column, meninges, cerebrospinal fluid in subarachnoid space
Gray Matter
- Dorsal horns: somatic + visceral sensory
- ventral horns: somatic motor neurons whose axons exit the cord via ventral roots
- Lateral horns (only in thoracic and lumbar regions): sympathetic neurons
- Dorsal root (spinal) ganglia: contain cell bodies of sensory neurons
Spinal cord trauma
Transection (cut): results in total motor and sensory loss in regions inferior to the damage
- Quadriplegia: transection in cervical region
- Paraplegia: transection bw T1 + L1
