Chapter 12 Flashcards
Central Nervous System
Brain and Spinal Cord. Where all communication go through the body
Cephalization
Increase number of neurons in the head
Prosencephalon
Forebrain
Encephalon - brain
Telencephalon - end brain
Diencephalon - interbrain
Mesencephalon
Mid brain
Remains undivided. Part of the brain stem
Rhombencephalon
hind brain
Metencephalon - after the brain
Myelencephalon - spinal brain
Development of Neural Tube
Primary brain vesicles
Brain
Cerebrum
Cortex - Gray Matter
Nuclei - Cell Bodies
Cerebellum - Posterior region of the brain
Spinal Cord
Central cavity surrounded by a gray matter core (H - shaped)
Gray
short nonmyelinated - Contain cell bodies
White -
- Myelinated
- Contain primarily axons
- Dense coating of fatty myelin is what gives white matter color
4 Regions include cerebral hemisphere
- Cerebral
- Diencephalon
- Cerebellum
- Brain stem - Mid brain, Pon, Medulla Oblongata
Ventricles of the Brain
Lateral ventricles - on deep within each hemisphere. large C-shaped Cahmpbers
3rd Ventricle: located in Diencephalon
Dorsal (behind) to the pons
Filled with Cerebrospinal fluid
Diencephalon
- Thalamus
- Hypothalamus
- Epithalamus
Septum Pellucidum
Very thin median membrane that separates the Lateral Ventricle
Interventricular Foramen
Channel that is connected to the third ventricle
Central Aqueduct
Going to run through the mid brain connect to third and fourth ventricle
Fourth Ventricle
Extend to the canal - run through the spinal cord
hind dorsal to the pons and superior of medulla
The Brain
- 2 cerebral hemispheres - make up 83% mass of the brain
- Cerebellum
- Diencephalon
- Thalamus/Hypothalamus/
- Epithalamus)
- Brain stem
Gyri
Elevated ridges of tissue separated by sulci
Fissures
Deeper Grooves
Longitudinal Fissures - Separates the cerebral hemisphere
Transverse Cerebal Fissure - separates cerebral hemisphere from cerebellum
Sulci
Shallow groove
Sulci divide into 5 lobes
Temporal Lobe - primary auditory cortex
Parietal Lobe - somatosensory association
Occipital Lobe - posterior lobe, conscious
Insula Lobe - Covered by temporal, parietal, frontal
Frontal Lobe - anterior lobe of cerebrum, broca speech
Lobes of Brain
- Sulci divide into 5 lobes
- Central sulcus - lies in the frontal plane/separate frontal lobe
- Parieto-occipital Sulcus - located posteriorly on medial surface
- Lateral sulcus - outlines the flaplike temporal lobe
- Precentral/Postcentral Gyri
Precentral Gyri
Motor
Postcentral Gyri
Sensory Function
Sucli
Central Sulcus - Separates frontal lobe
Lateral Sulcus - outlines the flaplike temporal lobe
Cerebellum
Plays a role in motor function
Cerebral Hemispheres
- Cortex - Out gray matter
- White Matter - Axons
- Basal Nuclei - group of cell bodies
Cortex
Superficial gray matter
(Neuron cell bodies, Dendrites,
Unmyelinated fibers, Glial cells,
Blood vessels)
Cortex Functions
Sensation
Communication
Understanding
Involuntary
Movements
Memory
Functional Areas of the Cerebral Cortex
52 Cortical Area
Motor area - Voluntary
Sensory area: Conscious awareness of sensation
Association areas : Integrate diverse information
4 Generalizations about the cortex Motor Areas
- Motor/Sensory
All neurons in the cortex are interneurons
2.Tracts crossover at medulla - Hemispheres are not equal in function
(Hemispheric lateralization - specialization) - No functional area acts alone; conscious behavior involves the entire cortex
Primary motor cortex
forms the Corticospinal tracts
Located in precentral gyrus
Motor Areas
Primary Motor Cortex
premotor Cortex
Frontal eye fields
Broca’s area (outlined by dashes)
Prefrontal Cortex
Working memory for spatial tasks
Executive areas for task management
Working memory for object-recall task
Solving complex multi task problems
Sensory area
Primary somatosensory cortex - Somatic sensation
Somatosensory association cortex - Somatic Sensation
Gustatory cortex - Taste
Wernickes area
Primary Visual cortex - vision
Visual association area - vision
Auditory area - Hearing
Primary Auditory - Hearing
Premotor Cortex
Helps to plan movements, staging area
Broca’s
motor area of speech and also active as we plan our speech
Posterior Association Area of the Brain
- parts of: Temporal, Parietal, and Occipital lobes)
- Found in one hemisphere, usually the left
- Roles: Recognizing patterns/faces; localizing self/others in space/Binding
different sensory inputs into a whole - Involved in giving attention to a particular part of body
Cerebral White Matter
Deep myelinated fibers/ tracts
* Communication between the Cerebral cortex/Lower CNS center, and areas of the cerebrum
Basal Nuclei (NOT ganglia – PNS term)
*Subthalamic nuclei/Substantia nigra
* Receives inputs from entire cerebral cortex
* Regulate ATTN and cognition (limbic system and other areas)
Huntingtons
neurons of Putamen/Globus Pallidus degenerate =
involuntary movements; enhance dopamine
Parkinsons
Substantia Nigra nuclei degenerate ~ too little movement
(expressionless face, postural fixation, rigidity, tremor); block dopamine
Diencephalon
Central core of the forebrain
* Thalamus/Hypothalamus/Epithalamus (Pineal gland/Choroid Plexus)
* Encloses the 3rd ventricle
Thalamus
- Information “sorted out” and “edited”
- Gateway to the cerebral cortex
- Emotion and visceral function from hypothalamus; motor form
cerebellum
Thalamic Function: RELAY STATION!!
Afferent impulses - from all senses converge/synapse in the thalamus - spinal cord, brain stem, mid brain
Impulses of similar function are “sorted out,” edited, and relayed as a group = Relay Station
Key Role of Thalamus
in mediating Sensation, Motor activities (interacts with Cerebellum, Basal ganglia), Cortical arousal, Learning, and Memory
Hypothalamus
- Mamillary bodies – relay station for olfaction
Hypothalamus Functions
- seat of ANS – BP, HR, digestion, respiration, pupils
- Emotional response–limbic system, bio-rhythms; long-term stress
- Body temperature regulation – thermoregulation
- Satiety (glucose, AAs)
- H2O balance and thirst – osmoreceptors, ADH
- Sleep-wake cycles – circadian cycles (SCN)
- Endocrine system functioning – pituitary
Epithalamus
Pineal gland – Melatonin (released at night = promotes sleepiness)
* Melatonin – a hormone involved with sleep regulation, sleep-wake
cycles, and mood
* Choroid plexus – a structure that secretes cerebrospinal fluid (CSF)
Brain Stem
Nuclei that control Cranial
nerves III -IV
- Corpora quadrigemina – four
domelike protrusions of the dorsal
midbrain
Brain Stem : Superior colliculi –
visual
reflex centers (tracking
moving images, scanning
stationary image, pupillary
reflex, accommodation)
Brain Stem: Inferior colliculi –
Auditory reflex centers (startle reflex)
Midbrain Nuclei: Periaqueductal gray matter
Pain suppression/link between amygdala and ANS
Midbrain Nuclei: Substantia nigra
functionally linked to basal nuclei (involved in
controlling subconscious muscle activity/Lack of activity = Parkinsons)
Midbrain Nuclei: Cerebral peduncles
– two bulging structures that contain
descending pyramidal motor tracts (Corticospinal)
Pons
Contains: Tracts/Nuclei
Tracts of the Pons:
- Connect higher brain centers and the spinal cord (connects
midbrain above to medulla below) - Relay impulses between the Cerebrum Cerebellum
- Origin of Cranial nerves V, VI, and VII
Tract of Pons: Pneumotaxic center:
with medulla involved with respiratory rate
Medulla Oblongata
Most inferior part of the brain stem - cranial nerve Cranial nerves VIII-XII
Contains a choroid plexus associated with the 4th ventricle
Medulla Oblongata: Pyramids
two longitudinal ridges formed by corticospinal tracts
(large motor tracts)
Medulla Oblongata: Place of decussation of the pyramids
Crossover (90%) points of
the corticospinal tracts
Medulla Nuclei: Inferior olivary nuclei –
sensory (muscle/joint stretch position) to cerebellum
Medulla Nuclei: Vestibular nuclear complex
synapses that mediate/maintain equilibrium
Medulla Nuclei: Cardiovascular control center –
adjusts force and rate of heart contraction/smooth
muscle contraction (Vasomotor center)/dilation (controlled by hypothalamus)
Medulla Nuclei: Respiratory centers
rate/depth of breathing/partners with pons (controlled by hypothalamus)
Medulla Nuclei: Other reflex centers:
coughing, vomiting, sneezing, hiccups
The Cerebellum
Provides precise timing and appropriate patterns of
skeletal muscle contraction
Cerebellar Peduncles : SP
Cerebellum to midbrain (info to the cerebral motor cortex via the Thalamus)
Cerebellar Peduncles : MP
Cerebrum through the pons to cerebellum
Cerebellar Peduncles : IP
Medulla to Cerebellum (Proprio/vestibular nuclei through medulla to cerebellum)
Cerebellar Peduncles: Superior peduncles-up through midbrain
A “blueprint” of coordinated
movement is sent to the Cerebral motor cortex
Amygdala –
anger, danger, and fear responses, recognizes fearful facial expressions
Cingulate gyrus
–role in expressing emotions via gestures, and resolves mental conflict
Psychosomatic illnesses:
illness brought on by emotion
* One can react emotionally to conscious understandings
* One is consciously aware of emotion in one’s life
Hippocampal structures
convert new information into long-term memories
Reticular Formation: RAS
- Sends impulses to the cerebral cortex to keep it conscious and alert
- Filters out repetitive and weak stimuli
- LSD, EtOH, THC; Injury: can lead to irreversible coma
Reticular Formation: Motor Function
- Helps control coarse motor movements
- Autonomic centers regulate visceral motor
functions – e.g., vasomotor, cardiac, and respiratory centers
Alpha waves
low-amplitude, slow, synchronous waves indicating an “idling” brain:
Awake but relaxed
Beta waves
rhythmic, more irregular waves occurring during the awake and mentally alert state
awake and alert
Theta waves
more irregular than alpha
waves; common in children/adults experiencing emotional stress/on drugs (LSD, mushrooms)
Common in children
Delta waves
high-amplitude waves seen in deep sleep and when RAS is damped (anesthesia)/normal in awake infants/In adult indicate brain damage
deep sleep
Protection of the Brain
Bone, Meninges, and Cerebrospinal fluid
Blood-brain barrier
Harmful substances are shielded from the brain
Dura Mater
- Leathery, strong meninx
- Composed of 2 layers: Periosteal/Meningeal
- The two layers separate in certain areas and form
Dural sinuses
Arachnoid Mater
The middle meninx, which forms a loose brain covering
Beneath the arachnoid = Subarachnoid space filled with CSF/large blood vessels
Pia
delicate connective tissue/clings tightly to brain
Cerebrospinal Fluid (CSF) Production
Watery solution similar in composition to blood plasma/ formed by Ependymal cells of Choroid Plexus
Cerebrospinal Fluid (CSF) Production :
- Contains less protein/different ion concentrations than plasma
- Forms a liquid cushion = Gives buoyancy to the CNS organs
- Prevents the brain from crushing under its own weight
- Protects the CNS from blows/other trauma
- Nourishes the brain and carries chemical signals throughout it
Production Rate: CSF
*Volume of CSF: in humans is ~150 ml
*Production rate of 21 ml/hr = 500ml/day
*The turnover rate of total CSF : 8 hr for humans
*Homeostatic Imbalance: Hydrocephalus
Choroid Plexuses
Clusters of capillaries which hang from the roof of each ventricle + Ependymal cells that form tissue fluid
filtrate = CSF
- Ependymal cells have ion pumps that allow them to alter ion concentrations of the CSF
- Help cleanse CSF by removing wastes
Traumatic Brain Injury : Concussion
alteration in brain function
following blow to head
Traumatic Brain Injury : Contusion
Concussion leading to bruising of brain/permanent damage
Traumatic Brain Injury : Subdural/Subarachnoid Hematoma
bleeding from ruptured vessels into these spaces
Traumatic Brain Injury : Cerebral edema
swelling of the brain
Cerebrovascular Accidents (Strokes): Ishemia)
Caused when blood circulation to the brain is
blocked
Cerebrovascular Accidents (Strokes): Necrosis)
brain tissue dies
Cerebrovascular Accidents (Strokes)
- Most commonly caused by blockage of a cerebral
artery - Other causes include compression of the brain by
hemorrhage or edema, and atherosclerosis - Tissue plasminogen activator (TPA) is the only
approved treatment for stroke
Cerebrovascular Accidents (Strokes): Transient ischemic attacks (TIAs)
temporary episodes of reversible cerebral ischemia
Degenerative Brain Disorders: Alzheimer’s disease
progressive degenerative disease of the brain that results in dementia (Beta amyloid plaques)
Degenerative Brain Disorders: Parkinson’s disease
degeneration
Degenerative Brain Disorders: Substantia nigra -
results in too little movement
(Lack of Dopamine)
Degenerative Brain Disorders: Huntington’s disease
a fatal hereditary disorder caused by accumulation of the mutant protein Huntingtin that leads to degeneration of the basal nuclei ie results in too much movement
Ascending Pathways: Neuronal Composition 1st
- Cutaneous/Proprio → Spinal
Cord/Brainstem - Cell Body: Dorsal
Root/Cranial Nerve Ganglia - Synapse with 2nd order
Ascending Pathways: Neuronal Composition 2nd
- Cell Body: Posterior horn
spinal cord/Medullary nuclei - From Spinal Cord/Medulla
→ Thalamus/Cerebellum - Synapse with 3rd order
neurons (Only in
Thalamus/No 3rd order
neurons in Cerebellum)
Ascending Pathways: Neuronal Composition 3rd
- Cell Body: located in
Thalamus - From Thalamus →
Somatosensory Cortex in
Parietal lobe of Cortex
