Chapter 12 Flashcards
The cerebellum
- Dorsal to brainstem, inferior to occipital lobe
- subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction
- tests: balance, coordination, finger-nose
- Involved in learning motor tasks (sport, musical instruments)
The pons belongs to which major brain region
brain stem
Severe damage to which of the following brain regions would result in death?
medulla oblongata
Which of the following brain systems is heavily involved in mediating emotional responses?
limbic system
Autonomic Nervous System
the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
Afferent nervous system
transmits impulses from peripheral organs to the CNS
Sympathetic Nervous System
division of the nervous system that functions to produce localized adjustments (such as sweating as a response to an increase in temperature) and reflex adjustments of the cardiovascular system.
- > fight or flight
- > This response is characterized by the release of large quantities of epinephrine from the adrenal gland, an increase in heart rate, an increase in cardiac output, skeletal muscle vasodilation, cutaneous and gastrointestinal vasoconstriction, pupillary dilation, bronchial dilation, and piloerection. The overall effect is to prepare the individual for imminent danger.
Parasympathetic nervous system
predominates in quiet “rest and digest” conditions
The main purpose of the PNS is to conserve energy to be used later and to regulate bodily functions like digestion and urination.
Regions and organization of the CNS
Adult brain regions:
1. Cerebral hemispheres (cortex, cerebral white matter and basal ganglia)
- Diencephalon (thalamus, hypothalamus, epithalamus)
- Brain stem (midbrain, pons, and medulla)
- Cerebellum
- > Spinal cord
what is the difference between white and gray matter
White matter= axons, myelinated fibers
Gray matter= cell bodies, unmyelinated fibers
Ventricles of the brain
- > connected to one another and to the central canal of the spinal cord
- > lined by ependymal cells
- > Contain cerebrospinal fluid
- 2 C-shaped lateral ventricles
- third ventricle
- fourth ventricle
Hydrocephalus
compression of brain due to build up of spinal fluid in ventricles
Cerebral hemispheres
Surface markings
- > Ridges (gyri)
- > shallow grooves (sulci)
- > deep grooves (fissures)
5 lobes per hemisphere:
- > frontal
- > parietal
- > temporal
- > occipital
- > insula
Cerebral cortex
Site of conscious mind:
awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding
The 3 types of functional areas are:
-> motor areas- control voluntary movement
- > sensory areas- conscious awareness of sensation
- > association areas- integrate diverse info
motor areas (frontal lobe)
Primary (somatic) motor cortex:
- > control of skeletal muscles
- > pyramidal cells-> pyramidal tracts
Premotor cortex:
-> plans movements, coordinates movements of several groups into complex tasks (musical instrument)
Broca’s area:
->motor speech area (left hemisphere)
Regions and Organization of the CNS
- > Adult brain regions:
1. Cerebral hemispheres: (cortex, cerebral white matter, and basal ganglia)
- Diencephalon: (thalamus, hypothalamus, epithalamus)
- Brain stem: (midbrain, pons, and medulla)
- Cerebellum
- >Spinal cord
what is the difference between white and gray matter?
- > white matter= axons
- >gray matter=cell bodies
Ventricles of the brain
- > connected to one another and to the central canal of the spinal cord
- > lined by ependymal cells (Ependymal cells are ciliated-epithelial glial cells that develop from radial glia along the surface of the ventricles of the brain and the spinal canal. They play a critical role in cerebrospinal fluid (CSF) homeostasis, brain metabolism, and the clearance of waste from the brain.)
- > contain cerebrospinal fluid
- 2 C-shaped lateral ventricles
- third ventricle
- fourth ventricle
Hydrocephalus
compression of brain due to build up of spinal fluid in ventricles
Primary somatosensory cortex (parietal lobe)
touch
association areas
understanding of sensory info
sensory areas
visual areas
auditory areas
olfactory area
smell
visceral sensory area
full bladder
vestibular cortex
equilibrium
visual areas (occipital lobe)
Primary visual (striate) cortex:
- extreme posterior tip of the occipital lobe
- receives visual info from the retinas
- > Visual association area:
- uses past visual experiences to interpret visual stimuli (e.g., color, form, and movement)
- recognizes faces and familiar objects
auditory areas (temporal lobe)
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
- > Most complicated cortical region
- > Involved with intellect, cognition, recall, and personality
- > Contains working memory needed for judgment, reasoning, persistence, and conscience
- > Develops slowly in children, depends on feedback from social environment
- > Lesions in this area can cause personality changes
lateralization of cortical function
lateralization: division of labor between hemispheres
- > left hemisphere:
- controls language, math, and logic
- > right hemisphere:
- insight, visual-spatial skills, intuition, and artistic skills
**Left and right hemispheres communicate via fiber tracts in the cerebral white matter
cerebral white matter
Myelinated fibers and their tracts
Responsible for communication:
- > Commissures-
- Connect the two hemispheres (corpus callosum)
->Association fibers—
connect different parts of the same hemisphere
->Projection fibers—
connect the hemispheres with lower brain or spinal cord
commissures
*Connect the two hemispheres (corpus callosum)
association fibers
connect different parts of the same hemisphere
projection fibers
connect the hemispheres with lower brain or spinal cord
basal nuclei (ganglia)
- > subcortical nuclei
- > functions:
- help regulate attention and cognition
- regulate intensity of slow or stereotyped movements
- inhibit unnecessary movements
Disorders in Basal Ganglia causes too much movement as in Huntington’s Disease or too little movement in Parkinson’s Disease
diencephalon
3 paired structures:
- > thalamus
- relay station
- > hypothalamus
- homeostasis
- > epithalamus
- melatonin
these 3 structures enclose third ventricle
thalamic function
- > gateway to the cerebral cortex (relay station)
- > sorts, edits, and relays info (afferent impulses from all senses)
- > thalamus means “inner room”
hypothalamic function
- > autonomic control center
- e.g., blood pressure, rate and force of heartbeat, digestive tract mobility
- > emotional response (limbic system): involved in the perception of pleasure, fear, and rage and in biological rhythms and drives
- > fearful person-has a pounding heart, high blood pressure, sweating, dry mouth
- > also regulates body temp, food intake, water balance, thirst
- > connected to the pituitary gland
epithalamus
- > part of diencephalon
- > pineal gland-secretes melatonin (helps regulate sleep-wake cycles)
brain stem
3 regions:
-> midbrain: substantia nigra (parkinsons disease)
- > pons- “bridge”
- > medulla oblongata- connects to spinal cord
substania nigra
- > functionally linked to basal ganglia (nuclei)
- > produces neurotransmitter dopamine
- > degeneration of these dopamine releasing neurons causes parkinsons disease
medulla oblongata
-> autonomic reflex centers- unconscious activity
Cardiovascular center:
- > cardiac center adjusts force and rate of heart contraction
- > vasometer center adjusts blood vessel diameter
Respiratory center:
- > generate respiratory rhythm
- > control rate and depth of breathing
Damage to brain stem, especially medulla oblongata results in death
the cerebellum
- > dorsal to brainstem, inferior to occipital lobe
- > subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction
- > tests: balance, coordination, finger-nose
- > involved in learning motor tasks (sports, musical instruments)
functional brain systems
limbic system:emotional brain
- > hippocampus (stress)
- > amygdala
- > cingulate gyrus
- > hypothalamus (diencephalon)
reticular formation: wakefulness
limbic system
emotional or effective brain
->amygdala: recognizes angry or fearful facial expressions, asses danger, elicits the fear response, “body’s alarm system”
- > cingulate gyrus: plays a role in expressing emotions via gestures, and resolves mental conflict
- limbic system & olfactory area related
- odors recall memories
Limbic system: emotion and cognition
- the limbic system (emotional brain) interacts with the prefrontal lobes (thinking brain), therefore:
- > our emotions sometimes override logic and conversely why reason can stop us from expressing our emotions
- > hippocampus and amygdala-play a role in memory
“use your head but trust your heart”
reticular formation
RAS (reticular activating system):
->sends impulses to the cerebral cortex to keep it conscious and alert
- > filters out repetitive stimuli
- > RAS inhibited by sleep cnters (depressed by EtOH and tranquilizers)
- > severe injury results in permanent unconsciousness (coma)
organizations
- Pre/motor cortex: ?
- prefrontal cortex: problem solving
- hypothalamus: autonomic center
- sensory cortex: touch, temp, pain
- thalamus:relay station
- cerebellum: movement
- hippocampus:memory
- amygdala: emotion
- pons:part of brainstem
- spinal cord:pathways
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)
- Two major types of sleep (defined by EEG patterns);
- Nonrapid eye movement (NREM)
- Rapid eye movement (REM)
importance of sleep
- slow wave sleep (NREM stages 3 &4) is presumed to be the restorative stage
- people deprived of REM sleep become moody and depressed
- sleep deprivation is linked to increased risk of heart diease, DM, kidney disease, and stroke, and HBP
- REM sleep may be a reverse learning process where superfluous info is purged from the brain
- daily sleep requirements decline with age
language
language implementation system:
- basal nuclei
- broca’s area (frontal lobe)
- wernicke’s area (temporal lobe)
-corresponding areas on the right side are involved with nonverbal language components
broca’s- expressive speech
wernicke’s- understanding speech
memory
-encoding, storage and retrieval of info
- 2 stages:
- short term memory (STM, or working memory)- temporary holding of info; limited to 7 or 8 pieces of info
*long term memory has limitless capacity
transfer of memory from STM to LTM
- factors that affect transfer from STM to LTM
- emotional state: best if alert, motivated, surprised, and aroused (norepinephrine)
- rehearsal- repetition and practice
- association-tying new info with old
- automatic memory-subconscious info stored in LTM
protection of the brain
- bone (skull)
- membranes(meninges)
- watery cushion (cerebrospinal fluid)
- blood-brain barrier (filters toxins, but not lipid soluble like alcohol)
meninges
-cover and protect the CNS
3 layers:
-Dura mater: “tough mother” fibrous CT (consists of periosteal and meningeal)
- Arachnoid matter: “spider”, subarachnoid contains CSF and blood vessels
- pia mater: “gentle mother” delicate CT, clings to brain like saran wrap
cerebrospinal fluid (CSF)
functions:
-Gives buoyancy to the CNS organs – floats the brain
- Protects the CNS from blows and other trauma
- Nourishes the 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 the foramen magnum
- ends at conus medullaris at L1 vertebra
functions:
- provides 2 way communication to and from the brain
- contains spinal reflex centers
spinal cord protection
protected by vertebral column, meninges, cerebrospinal fluid in subarachnoid space
gray matter
-dorsal horns:
somatic and 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
Ascending tracts transmit ______ impulses while descending tracts conduct ______ impulses.
sensory;motor
spinal cord trauma
transection (cut):
-results in total motor and sensory loss in regions inferior to the damage
- quadriplegia-transection in the cervical region
- paraplegia- transection between T1 and L1
