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109 Cards in this Set

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Prosencephalon (forebrain) turns into what secondary brain vesicles?
Telencephalon
Diencephalon
Mesencephalon (midbrain) turns into what secondary brain vesicles?
Mesencephalon
Rhombencephalon (hindbrain) turns into what secondary brain vesicles?
Metencephalon
Myelencephalon
Telencephalon turns into what Adult brain structures and neural canal regions?
Cerebrum: cerebral hemishperes (cortex, white matter, basal nuclei)
Lateral Ventricles
Diencephalon turns into what Adult brain structures and neural canal regions?
Diencephalon (thalamus, hyphothalamus, epithalamus), retina
Third Ventricle
Mesencephalon turns into what Adult brain structures and neural canal regions?
Brain Stem: midbrain
Cerebral aqueduct
Metencephalon turns into what Adult brain structures and neural canal regions?
Brain Stem: Pons
Cerebellum
Fourth ventricle
Myelencephalon turns into what Adult brain structures and neural canal regions?
Brain Stem: medulla oblongata
Fourth Ventricle
Spinal Cord turns into what neural canal regions?
central canal
Ventricles
hollow, ventricular chambers filled with cerebrospinal fluid
1. Lateral Ventricles- one in each cerebral hemisphere, large c-shaped, reflex pattern of cerebral growth and seperated by septum pellucidum
2. third ventricle- narrow, in the diencephalon via channel called interventricular foramen.
3. Fourth ventricle- continuous with the third, via the cerebral aqueduct that runs through the midbrain. Lateral apertures on side and median aperture on roof
Components of the CNS
COMPONENTS: Brain & Spinal Cord
Location of the CNS
LOCATION: Dorsal Cavity, Brain – cranial cavity, Spinal cord – Spinal Cavity
Cephalization
Cephalization: increase concentration of neurons, sensory structures in anterior part of organism forming a head area with a brain.
Protection of the CNS
1. Skull
2. Meninges (Meninx): 3 membranes that protect the CNS
3. Cerebrospinal Fluid
Meninges
- cover & protects
- protect blood vessels and enclose venous sinuses
- contain cerebral spinal fluid
- forms partitions within the skull
Dura Mater, Arachnoid Mater, Pia Matter
Dura Mater
leathery, double membrane, outer layer of the brain with the outer membrane attached to the skull
- in places attaches brain to skull to prevent excessive movement; In spinal cord only a single membrane, does not attach to vertebrae
-Made of 2 layers:
1. Periosteal
2. Meningeal (deeper)
Arachnoid Mater
middle layer, loosely covers brain
- separated from dura mater by subdural space
- between arachnoid mater and pia mater is the subarachnoid
space
- contains the largest blood vessels serving the brain
Pia Mater
inner layer, composed of delicate connective tissue with many small blood vessels
- clings tightly to the brain
Cerebrospinal Fluid
found in 4 ventricles (2 lateral, third, fourth)
- liquid cushion, gives buoyancy to CNS organs
- floats the jelly-like brain
- protection from blows and trauma
- helps nourish the brain
- derived from blood plasma but with a different composition
- formed from the choroid plexuses
What does the brain weigh?
- weighs ~ 3.5 lbs (1600 g)
4 Major Parts of the Brain
A. FOUR MAJOR PARTS OF THE BRAIN:
1. Cerebrum: Cerebral hemispheres
2. Cerebellum
3. Diencephalon: Thalamus, Hypothalmus, Epithalamus
4. Brain stem: Midbrain, Pons, Medulla oblongata
Cerebrum
Cerebrum; largest, divided into two hemispheres, ~ 83% of total brain weight
Functions of Cerebrum
Functions of Cerebrum: motor functions, speech, sensory center, visual center, auditory center, olfactory center, conscious thought, judgment, memory, reasoning, will power.
Longitudinal Fissure
Longitudinal Fissure:
separates the two hemispheres
Transverse Fissure
Transverse Fissure:
separates cerebral hemisphere from the cerebellum
3 Basic Regions of Cerebrum
3 Basic Regions of Cerebrum:
1. Cortex
2. White Matter
3. Basal Nuclei
Cortex
Cortex:
perceive, communicate, remember, understand, appreciate, initiate voluntary movements, “conscious behavior”
- 2-4 mm thick
- ~ 40% of total brain mass
White Matter
White Matter:
- communication between cerebral areas and cerebral cortex and lower CNS centers
- mainly myelinated fibers bundled into large tracts
Basal Nuclei
Basal Nuclei:
- gray matter areas located deep within the white matter of the
cerebral hemispheres
- may play role in motor control??
Generalizations about the Cerebrum (Cortex):
Generalizations about the Cerebrum (Cortex):
1. 3 kinds of functional areas
2. Each hemisphere acts contralateral
3. Lateralization of hemispheres
3 Functional Areas of Cerebrum:
3 Functional Areas of Cerebrum:
a. motor: control voluntary motor function
b. sensory: provide for conscious awareness of sensations
c. association: act mainly to integrate diverse information for purposeful action
Contralateral
contralateral:
each side concerned with sensory and motor functions of the opposite side
Lateralization of Hemispheres
Lateralization of hemispheres
"split brain concept"
a. ~ 90% of people are left cerebral dominate
- left hemisphere dominate: mathematical abilities, logic
- right hemisphere dominate: visual-spatial skills, intuition,
emotion, art and music appreciation
- most are right handed
b. ~ 10% of people are right cerebral dominate or neither
Dyslexia
Dyslexia:
reading disorder, intelligent people reverse order of
letters, syllables, numbers
- has been attributed in some cases to a lack of cerebral dominance
Diencephalon
Diencephalon:
composed of three major regions
Thalamus, Hypothalamus, Epithalamus
- surrounded by the cerebral hemispheres, enclose the third
ventricle
Thalamus
Thalamus:
relay station for incoming and outgoing nerve
impulses, sorts out information
- mediates sensations, motor activities, cortical arousal, memory
Hypothalamus
Hypothalamus:
Autonomic nervous control (regulates parasympathetic and sympathetic systems of ANS)
- Cardiovascular control, temperature control, appetite
control, water balance, gastrointestinal control, emotional
state, sleep control, thirst, Main Visceral Control Center
- An endocrine gland: Produces ADH & Oxytocin, regulates hormonal output of anterior pituitary gland
- ADH – antidiuretic hormone, water reabsorbed in kidney
Epithalamus
Epithalamus:
dorsal most part of diencephalon
- pineal gland (body): extends from epithalamus, produces
melatonin: mood & sleep/wake cycles
Choroid Plexus
Choroid Plexus:
capillary knot that hangs down into the ventricles
Limbic System
Limbic System:
Emotional brain – involves cerebral and diencephalon to mediate emotional response
Mammary Bodies
Mammary bodies: olfactory relay stations
Cerebellum
Cerebellum:
-processes info from cerebral motor cortex and provides instructions
2 hemispheres connected by the VERMIS- Tree-like
pattern (within the cerebellum) called ARBOR VITAE ("tree of life")
- maintenance of balance, muscle tone, and coordination of skeletal muscle contractions, posture
- process information from PROPRIOCEPTORS: receptors located in a joint, muscle, tendon, concerned with locomotion, posture and muscle tone.
The Brain Stem
The Brain stem:
3 regions: Midbrain, Pons, Medulla Oblongata
- responsible for automatic behaviors necessary for survival
- 10 of 12 pairs of cranial nerves
Midbrain
Midbrain:
between the pons and the diencephalon
- conduction pathway between higher and lower brain functions
- visual and auditory control centers
- motor centers
Pons
Pons:
respiratory center, relay between medulla oblongata
and cerebrum, relay information from cerebrum to cerebellum
Medulla Oblongata
Medulla oblongata:
-in midbrain
vasoconstrictor center, respiratory center, cardiac center, sensory relay to cerebellum,
centers for controlling: vomiting, coughing, hiccuping,
swallowing, and sneezing
Decussation
decussation:
where crossover occurs, contralateral of cerebral
hemispheres
Reticular formation
Reticular formation:
Maintains cerebral cortical alertness (reticular activating system), Helps regulate skeletal & visceral muscle activity.
-Extends through central core of the medulla oblongata, pons and midbrain
-These neurons form thee broad columns along the length of the brain stem:
1. raphe nuclei
2. medial large cell group
3. lateral small cell group.
The Spinal Cord
The Spinal Cord:
- Begins at foramen magnum and extends to the level of the first
lumbar vertebra
- Lies within the vertebral column
- Major reflex center
- Two-way conduction pathway to and from the brain
- 31 pairs of spinal nerves
- divided into right and left halves by the anterior median fissure & the
posterior median sulcus
Spinal Cord Enlargements
Spinal Cord Enlargements:
1. Cervical
area where nerves come off to innervate arms
2. Lumbar
area where nerves come off to innervate legs
Cauda equina
Cauda equina:
looks like horse tail, collection of nerve roots at the inferior end of the vertebral column
conus medullaris
conus medullaris:
termination of the spinal cord. “cone-shaped”
filum terminale
filum terminale:
extends down from the conus medullaris to the posterior surface of the coccyx, where it attaches fibrous extensions of the pia mater
Gray Matter
Gray matter:
appears in the shape of a "butterfly", called commissure
White matter
White matter:
surrounds gray matter, called funiculi
1. sensory areas 2. motor areas 3. ascending and descending tracts
- Made of Myelinated fibers bundled into large tracts
- Fibers classified by way in which they run
1. Commisural Fibers- connect corresponding grey ares, linking the two hemispheres
2. Association Fibers- Connect parts in same hemisphere
3. Projection Fibers- ascending or descending
Ascending Tracts
ascending:
(sensory) conduct sensory impulses upward through
chains of 2 or 3 successive neurons to various parts of the brain
Descending Tracts
descending:
(motor) conduct motor impulses from brain to
spinal cord. Two different groups:
Pyramidal: major motor pathway, voluntary movements, precise or skilled movement like threading a needle or writing
Others: The Rest
Reflex Arc
Reflex Arc:
Reflexes (automatic reaction) occur over neural pathways called reflex arcs. Reflex Arcs have five essential components:
1.receptor
2.sensory neuron
3.CNS integration center
4. motor neuron
5. effector
-unconscious and involuntary
Is the brain involved?
NO!
Reflex Arc Steps
Reflex Arc Steps:
After receiving stimulus:
1. sensory receptors
2. sensory neurons
3. interneuron
4. motor neuron
5 .effectors (muscles, glands)
Motor Areas of Cerebral Cortex
Motor Areas of Cerebral Cortex:
1. Primary Motor Cortex
2. Premotor Cortex
3. Broca's Area
4. Frontal Eye Field
Motor Areas of Cerebral Cortex:
1. Primary (Somatic) Motor Cortex
Motor Areas of Cerebral Cortex:
1. Primary Motor Cortex:
-located in precentral gyrus of frontal lobe
-Large Pyramidal cells in these gyri allow us to consciously control the precise or skilled voluntary movements of our skeletal muscles.
-form pyramidal (corticospinal) tracts
-damage (from stroke) paralyzes muscles on side of body opposite that of lesion (only voluntary movement lost)
Somatotopy
Somatotopy:
The entire body is represented spatially in the primary motor cortex of each hemisphere.
Ex. The pyramidal cells that control foot movement are in one area and hand movement is in the other. Mapping of the body is called Somatotopy
Motor Areas of Cerebral Cortex:
Premotor Cortex
Motor Areas of Cerebral Cortex:
Premotor Cortex:
Anterior to precentral gyrus in the frontal lobe.
-Controls learned motor skills of a repetitious or patterned nature, ex. playing music, typing.
-damage results in loss of learned skills, but movement of muscles is often still possible
Motor Areas of Cerebral Cortex:
Broca's Area
Motor Areas of Cerebral Cortex:
Broca's Area:
anterior to the inferior region of the premotor area
1. present in one area only (gen. left)
2.special motor speech area – controls muscles of tongue, throat & lips during (& possibly in planning of) speech
Motor Areas of Cerebral Cortex:
Frontal Eye Field
Motor Areas of Cerebral Cortex:
Frontal Eye Field:
partially in and anterior to the premotor cotrex and superior to Broca's area.
-involves voluntary movement of the eyes
Sensory Areas of Cerebral Cortex
Sensory Areas of Cerebral Cortex
1. Primary Somatosensory Cortex
2. Somatosensory Association Cortex
3. Visual Areas
4. Auditory Areas
5. Olfactory Cortex
6. Gustatory Cortex
7. Visceral Sensory Area
8. Vestibular (Equilibrium) Cortex
Sensory Areas of Cerebral Cortex:
Primary Somatosensory Cortex
Sensory Areas of Cerebral Cortex:
Primary Somatosensory Cortex:
-in the postcentral gyrus of the parietal lobe. Posterior to the primary motor cortex
-spatial discrimination: receive input from sensory receptors in skin & proprioceptors in skeletal muscles & identify region being stimulated
Sensory Areas of Cerebral Cortex:
Somatosensory Association Cortex
Sensory Areas of Cerebral Cortex:
Somatosensory Association Cortex:
-posterior to primary somatosensory cortex
-integrates sensory inputs (temp., pressure…) relayed to it by primary somatosensory cortex
Sensory Areas of Cerebral Cortex:
Visual Areas
Sensory Areas of Cerebral Cortex:
Visual Areas:
-primary visual (striate) cortex: posterior tip & medial aspect of occipital lobe; receives visual information from retinas
-visual association area: surrounds primary visual area in occipital lobe; interprets visual stimuli using past visual experiences
Sensory Areas:
4. Auditory Areas:
Sensory Areas:
4. Auditory Areas:
-primary auditory cortex: temporal lobe next to lateral sulcus; determines pitch, rhythm, & loudness
-auditory association area: posterior to primary auditory cortex; perception of sound & sound memory
Sensory Areas:
5. Olfactory Cortex
Sensory Areas:
5. Olfactory Cortex: Smell
-frontal lobes just above orbits & medial aspects of temporal lobes
-part of “rhinencephalon”; conscious awareness of odors
Sensory Areas:
6.Gustatory Cortex:
Sensory Areas:
6.Gustatory Cortex:
-parietal lobe just deep to temporal lobe; perception of taste stimuli
Sensory Areas:
7. Visceral Sensory Area
Sensory Areas:
7. Visceral Sensory Area:
Cortex of the insula posterior to the gustatory cortex.
-involved in conscious perception of visceral sensations
-upset stomach, full bladder, lungs
Sensory Areas:
8.Vestibular Cortex:
Sensory Areas:
8.Vestibular Cortex:
posterior region of insula deep to temporal lobe; conscious awareness of balance
Multimodal Association Areas:
Anterior Association Area:
Prefrontal Cortex
Multimodal Association Areas:
Anterior Association Area:
Prefrontal Cortex:
anterior portion of frontal lobe; most complex cortical region
-involved with intellect, cognition, recall & personality; necessary for production of abstract ideas, judgment, reasoning, planning, conscience, etc.
Multimodal Association Areas:
Posterior Association Area
Multimodal Association Areas:
Posterior Association Area:
-Large region in parts of temporal, parietal and occipital lobes
-role in recognizing faces, patterns, localizing us and our surroundings in space, and in binding different sensory inputs in a coherent whole.
-many parts involved in understanding written and spoken language
Multimodal Association Areas:
Limbic Association Area
Multimodal Association Areas:
Limbic Association Area:
-includes cingulate gyrus, the parahippocampal gyrus, and the hippocampus. Part of Limbic system.
-Provides the emotional impact that makes a scene important to us.
Chief Homeostatic Roles of Hypothalamus:
Chief Homeostatic Roles of Hypothalamus:
1. Autonomic Control Center
2. Center for emotional response
3. Body temperature regulation
4. Regulation of food intake
5. Regulation of water balance and thirst
6. Regulation of sleep-wake cycles
7. Control of endocrine system functioning
Cerebellar Peduncles
Cerebellar Peduncles:
Three paired fiber tracts connect the cerebellum to the brain stem.
-ipsilateral- fibers entering and leaving cerebellum are from and to the same side of the body
1.Superior Cerebellar Peduncles
2. Middle Cerebellar Peduncles
3. Inferior Cerebellar Penduncles
Cerebellar Peduncles:
1.Superior Cerebellar Peduncles:
Cerebellar Peduncles:
1.Superior Cerebellar Peduncles:
connect cerebellum and midbrain; carry instructions from neurons in the deep cerebellar nuclei to the cerebral motor cortex via thalamic relays.
Cerebellar Peduncles:
2. Middle Cerebellar Peduncles:
Cerebellar Peduncles:
2. Middle Cerebellar Peduncles:
carry a one way communication from the pons to the cerebellum advising the cerebellum of voluntary motor activities initiated by the motor cortex (via relays in the pontine nuclei)
Cerebellar Peduncles:
3. Inferior Cerebellar Penduncles
Cerebellar Peduncles:
3. Inferior Cerebellar Penduncles:
Connect medulla and cerebellum. These peduncles convey sensory info to the cerebellum from:
1. muscle proprioceptors through the body
2. the vestibular nuclei of the brain stem, which are concerned with equilibrium and balance
Cerebellar Processing:
Cerebellar Processing:
1. Motor areas of the cerebral cortex via relay nuclei in the brain stem, notify the cerebellum of their intent to initiate voluntary muscle contractions
2. The cerebellum receives info from proprioceptors throughout the body (regarding tension in the muscles and tendons, and joint position) and from visual and equilibrium pathways. This info enables the cerebellum to evaluate body position and momentum.
3. The cerebellar cortex calculates the best way to coordinate the force, direction, and extent of muscle contraction to prevent overshoot, maintain posture and ensure smooth coordinated movements.
4. Via the superior peduncles, the cerebellum dispatches to the cerebral motor cortex its blueprint for coordinating movement. Cerebellar fibers also send info to brain stem nuclei which in turn influence motor neurons of the spinal cord.
Reticular Activating System (RAS)
Reticular Activating System (RAS):
-Arm of reticular formation
-Impulses from all the great ascending sensory tracts synapse with RAS neurons, keeping them active and enhancing their arousing effect on the cerebrum.
-Acts like a filter for the flood of sensory inputs.
-The RAS and the cerebral cortex disregard 99% of all sensory stimuli.
Brain Wave Patterns and the EEG:
Electroencephalogram or EEG:
Brain Wave Patterns and the EEG:
Electroencephalogram or EEG:
records some aspects of electrical activity of neurons in the brain
Brain Wave Patterns and the EEG:
Brain Waves
Brain Wave Patterns and the EEG:
Brain Waves:
patterns of neuronal electrical activity recorded.
-generated by synaptic activity at the surface of the cortex, rather than by action potentials in the white matter
4 classes of Brain Waves
4 Classes of Brain Waves:
1. Alpha
2. Beta
3. Theta
4. Delta
Alpha Waves
Alpha Waves:
(8-13 Hz): indicate relaxed state of wakefulness
Beta Waves:
Beta Waves:
(14-25 Hz): indicate mental alertness (concentration)
Theta Waves:
Theta Waves:
(4-7 Hz): common in children; abnormal in adults
Delta Waves:
Delta Waves:
(< 4 Hz): seen during sleep & anesthesia; abnormal when awake (indicate brain damage)
Sleep & Sleep-Awake Cycles:
Sleep & Sleep-Awake Cycles:
-sleep is defined as a state of changed consciousness, from which a person can be aroused by stimulation (distinguished from coma, where a person cannot be aroused)
-2 major types of sleep:
-NREM (non-rapid eye movement) sleep: 4 stages ending in slow-wave sleep
-REM (rapid eye movement) sleep: appears after slow-wave sleep; normally occurs about every 90 minutes
-Most dreams occur during REM sleep (nightmares most often occur during stage 3 & 4 NREM sleep)
Language:
Lesion in Broca's Area
Lesion in Broca's Area:
can understand language but have difficulty speaking it
Language:
Lesion in Wernicke's Area:
Language:
Lesion in Wernicke's Area:
able to speak but produce a nonsense referred to as "word salad"
Memory
Memory:
-involves the storage & retrieval of information
What plays a role in memory processing?:
What plays a role in memory processing?:
-memory storage occurs in stages & is continually changing
-the hippocampus of the limbic system & surrounding structures play roles in memory processing
-structural changes that encode memory) are widely distributed in the brain
Stages of Memory
Stages of Memory:
1. short-term memory (STM) or working memory: fleeting memory limited to 7 or 8 chunks of information
2. long-term memory (LTM): appears to have limitless capacity
-transfer of information from STM to LTM is enhanced by:
-emotion tied to an event
-rehearsal
-association of new information with old information in LTM
-automatic (unconscious) memory
Categories of Memory:
categories of memory:
-fact (declarative) memory: learning explicit information (names, faces, words, dates…); stored with context
-skill (procedural) memory: less conscious memory; involves motor activity (riding a bike or playing a musical instrument); often stored without context
Memory Storage Pathway:
Memory storage pathway:
sensory perception in cerebral cortex -> hippocampus & amygdala -> diencephalon, basal forebrain & prefrontal cortex -> back to sensory cortex
Anterograde Amnesia:
Anterograde amnesia:
-ability to associate new information with old is lost; person lives in here & now, but can still learn skills
Retrograde amnesia:
Retrograde amnesia:
-loss of memories formed in the distant past
Formation of Cerebrospinal Fluid:
Formation of Cerebrospinal Fluid:
-cerebrospinal fluid: formed by choroid plexuses hanging from the roof of the ventricles
-capillaries feed choroid plexus; ependymal cells lining ventricles regulate content of filtrate
-hydrocephalus: excess CSF in ventricles (due to faulty drainage of CSF into subarachnoid space – caused by tumors, inflammation or developmental abnormalities, head injury or meningitis) causes increased pressure that can damage nerves; can be relieved by draining excess CSF into vena cava or abdominal cavity
Blood Flow to Brain:
Blood Flow to Brain:
-blood flows to brain via internal carotid & vertebral arteries
-internal jugular veins return blood to heart from head
Blood-Brain Barrier:
Blood-Brain Barrier:
-capillaries serving brain tissue have tighter junctions than most capillaries of body; let very little through
-bloodborne substances within capillaries of brain separated from extracellular space & neurons by continuous endothelium of capillary walls, thick basal lamina & astrocytes contacting capillaries
-selective barrier: allows diffusion of nutrients but not metabolic wastes to enter brain tissue
-ineffective against fats, fat soluble molecules (some drugs) & alcohol
-some beneficial drugs (for brain cancer or infections) also cannot pass
-brain injury or infection/inflammation may result in localized breakdown of blood-brain barrier
Spinal Cord
Spinal Cord:
enclosed within vertebral column; extends from foramen magnum of skull to level of first or second lumbar vertebrae
-two-way conduction path to & from brain
-major reflex center: spinal reflexes initiated & completed at spinal cord level
Multimodal Association Area of Cerebral Cortex:
Multimodal Association Area of Cerebral Cortex:
-seems to be where sensations, thoughts, and emotions become conscious; makes us who we are
-allows us to give meaning to the info that we receive, store it in memory if needed, tie it to previous experience and knowledge, and decide what action to take.
-Anterior, Posterior, and Limbic
In general, how does information flow in the brain?
In general, how does information flow in the brain?:
-From sensory receptors to the appropriate primary sensory cortex, then to a sensory association cortex and then on to the multimodal association cortex.
Sensory Areas of Cerebral Cortex:
Sensory Areas of Cerebral Cortex:
-Areas concerned with conscious awareness of sensation
-The sensory areas of the cortex occur in the parietal, insular, temporal, and occipital lobes
- Primary Somatosensory Cortex, Somatosensory Association Cortex, Visual Areas, Auditory Areas, Olfactory Cortex, Gustatory Cortex, Visceral Sensory Area, and Vestibular Cortex
Motor Areas of Cerebral Cortex:
Motor Areas of Cerebral Cortex:
-control voluntary movement
-lie in posterior part of frontal lobes
-Primary motor cotex, premotor cortex, Broca's area, and the frontal eye field.