Chapter 11: Nervous System II: Divisions of Nervous System

Short Term Memory

-Working memory -Closed neuronal circuit -Circuit is stimulated over and over -When stimulation ceases, memory also, does, unless it enters long-term memory via memory consolidation

What does the limbic system consist of?

Portions of frontal lobe Portions of temporal lobe Hypothalamus Thalamus Basal nuclei Other deep nuclei

Motor Areas (Pre-central sulcus)

Primary motor areas Broca's area Frontal eye field

Implicit (nondeclarative)

Procedural memory Associative learning Non-associative learning

3 major areas of Cerebrum

Sensory Moto Association *referred to as a cortex or cortices

What do both hemispheres participate in?

Sensory analysis, storing memories, and skeletal muscle control

How does ganglia control certain voluntary muscular activities?

-Via connections w/ motor cortex, thalamus, and cerebellum -Dysfunction in these nuclei associated w/ parkinson's, huntington's, ADHD, OCD

White Matter

Axons or nerve tracts

Functions of the Limbic System

Controls emotions (amygdala) Produces Feelings Interprets sensory/olfactory impulse

Structure of Cerebrum

Corpus Callosum Gyri Sulci Fissures

What does the fibers cross over?

Cross over each other in brainstem from one side of the other (decussation): Left side of body controlled by right

Crossed Extensor Reflex (example)

Crossing of sensory impulses within the reflex center to produce an opposite effect *Some interneurons inhibit antagonistic extensor muscles ipsilaterally and regulate contralateral leg muscles to maintain balance

What do the fibers of the corpus callosum allow for?

Dominant hemisphere to control/ receive motor, sensory, and decision making tasks

DAVE

Dorsal Afferent, Ventral Efferent

Types of Long-term memory

Explicit (declarative) Implicit (nondeclarative)

Parts of Cerebrum (forebrain)

Frontal Parietal Occipital Temporal Insula

Lobes of Cerebrum

Frontal lobe Parietal lobe temporal Occipital Insula aka 'island of reil'

Types of association areas

Frontal lobe associations areas Parietal Lobe Temporal Lobe Occipital lobe

Primary Motor Areas

Frontal lobes control voluntary muscles

Sulci

Grooves in gray matter (central sulcus)

What does the hypothalamus regulate?

HR and BP eating drinking temp circadian rhythms

What do association areas provide?

Higher intellectual processes Memory, reasoning, verbalization, judgement, emotions

Brainstem

Hindbrain and midbrain combined

What do the 2 enlargements supply?

Nerves to upper and lower limbs

Visual Area

Occipital Lobe Interprets vision

Periaqueductal Gray

Pain perception, MORs

Cutaneous Sensory area/ cortex

Parietal lobe Interprets sensations on skin

Amygdala

Part of the emotional control center of the brain and assigns an emotional 'value' to memory

What does brain stem control?

-The programmed, automatic behaviors critical to survival -Pathway for fiber tracts between the higher and lower neural centers and is associated w/ 10 of 12 cranial nerves -Connects brain to spine

What side is more dominant?

The left hemisphere is dominant in most individuals

What does the spinal cord allow?

Two-way communication between brain and the body

Superior Colliculus

Visual system, pointing

Finiculi

White matter columns forming tracts

Memory

a specific circuit of neurons which communicate to each other

Frontal Lobe association areas

concentrating planning complex problem solving emotional behavior

Withdrawal Reflex

flexor Reflex Prevents or limits tissue damage 3 nerve arcs

What happens if a memory is consolidated?

it is stored in various association areas of the cerebral cortex

Cerebral Cortex

-Thin layer of gray matter that constitutes the outermost portion of cerebrum (2-5mm think) -Contains 75% of all neuron cell bodies NS

Parietal Lobe association areas

-Understanding speech -choosing words to express thoughts and feelings -awareness of object and body forms

What does non-dominant hemisphere control?

-Nonverbal tasks -Motor tasks -Understanding and interpreting musical and visual patterns -Provides emotional and intuitive thought processes

Association Areas

-Regions that are not primary motor or primary sensory areas -Widespread throughout the cerebral cortex

What strengthens synaptic connections?

-Repeated stimulation of neuronal circuits

Explicit (declarative)

-Semantic memory -episodic memory

Thalamus

-Sensory inputs converge here (all but smell) are filtered and passed to the cerebral cortex for processing -Lots of connection with cortex -> exit ramp from spine

Spinal Cord

-Slender column of nervous tissue continuous w/ brain and brainstem -Extends downward through vertebral canal -Filum Terminale

Choroid Plexus

-Specialized capillaries -Releases cerebrospinal fluid

What does Dominant hemisphere control?

-Speech -Writing -Reading -Analytical skills -Computational skills

The midbrain

-Tectum (dorsal) and tegmentum -Periaqueductal gray -Superior colliculus -Inferior colliculus -Motor Nuclei

Functions of Brain

*Often in nerve centers of nuclei -Interpret sensations -Determine perception -Store memory -Reasoning -Make decisions -Coordinate muscular movements -Regulate visceral activities -Determine personality

Dura Mater (outer)

-"Tough mother" -Venous Sinuses

Pia Mater (inner)

-"faithful mother" -Encapsulates blood vessels

Arachnoid Mater

-"spiderweb-like" -Space contains cerebrospinal fluid (CSF)

Ventricles of the Brain

-4 -Interconnected cavities within cerebral hemispheres and brain stem -Continuous w/ central canal of spinal cord -Filled w/ cerebrospinal fluid (CSF) -Interventricular foramen (lats to 3rd) -Cerebral aqueduct (3rd to 4th)

Hypothalamus

-A collection of nuclei -Connected to pituitary gland -Controls autonomic nervous system

Meningitis

-An infection of the meninges -Bacterial and viral -Affects arachnoid and/ or pia maters

Occipital Lobe association areas

-Analyze and combine visual images w/ other sensory experiences -Face recognition

Reflexes

-Automatic, subconscious responses to stimuli wthin or outside the body -Maintain homeostasis ; carry out automatic actions (swallowing, sneezing, vomiting) -Simple reflex arc (sensory- motor) -Most common reflex arc (sensory- association- motor)

Long Term Memory

-Changes in the structure or function of neurons -Enhances synaptic transmission -LTP- long term potential -Allow consolidation

Cerebrospinal Fluid

-Circulates in ventricles, central canal of spinal cord, and subarachnoid space -Surrounds brain and spinal cord (blood= CSF barrier)

What is cerebrospinal fluid?

-Clear fluid similar to blood plasma -Only about 140 ml -Nutritive and protective -Reflects composition of body fluid -CSF floats the brain

Ascending Tracts (Axons)

-Conduct sensory impulses to the brain

Functions of Spinal Cord

-Conduit (pathway) for nerve impulses to and from brain and brainstem -Center for spinal reflexes (reflex arcs)

Memory

-Consequence of learning -Learning is the acquisition of new knowledge -Memory is the persistence of that knowledge and the ability to recall it at a later time

Layers of Meninges

-Dura Mater (outer) -Arachnoid mater -Pia Mater (inner)

Evolutionary Development of Brain

-Hindbrain (oldest) -Midbrain -Forebrain (most recent to develop)

Temporal Lobe association areas

-Interpret complex sensory experiences -Help understand speech and to read -Store memories of visual scenes music, and complex patterns

Fissures

-Longitudinal: separates the cerebral hemispheres -Transverse: separates cerebrum from cerebellum

Effects of Meningitis

-Loss of vision and hearing, paralysis, mental retardation, death

Meninges

-Membranes of CNS -Protects CNS

What are the 4 ventricles?

-lateral ventricles (2) (first= left and second = right) -Third ventricle (below Corpus callosum) -Fourth Ventricle (brainstem)

How many segments in spinal cord?

31 segs each giving rise to a pair of spinal nerve

Filum Terminale

A thin cord of CT attaches to upper surface of coccyx

Frontal eye field

Above Broca's area Controls voluntary movements of eyes and eyelids

What is down with excess or wasted CSF?

Absorbed by arachnoid granulations

What do association do?

Analyze and interpret sensory experiences

Broca's Area

Anterior to primary motor cortex Usually in left hemisphere controls muscles needed for speech Connected to Wernicke's

Sensory area for smell

Arises from centers deep within the cerebrum

Hindbrain

Basic, life-sustaining functions

Where does the spinal cord start and stop?

Begins at foramen magnum and terminates at the first and second lumbar vertebrae (L1/L2) interspace

Diencephalon

Between cerebral hemispheres and above the brainstem Surrounds the third ventricle

What does CNS consist of?

Brain and spinal cord

What does the brainstem connect to?

Brain to the spinal Cord

Gyri

Bums or convolutons

How does CNS communicate w/ PNS?

By way of spinal cord

Gray Matter

Cell bodies and interneurons

Major Parts of the brain

Cerebrum Diencephalon (forebrain) Cerebellum Brainstem (hindbrain)

Descending Tracts

Conduct motor impulses from the brain to motor neurons reaching muscles and glands

Corpus Callosum

Connects cerebral hemispheres (a commissure)

Forebrain

Includes the cerebral hemispheres

What do sulci and gyri act to do?

Increase surface area/volume of brain (more neurons)

Functions of Cerebrum

Interpreting impulses from sense organs Initiating voluntary movements Storing information as memory and retrieving stored information Reasoning Seat of intelligence and personality

Ganglia

Masses of gray matter deep within cerebral hemisphere (caudate, nucleus, putamen, and globus pallidus) -Produce dopamine Control certain voluntary muscular activities

Parts of Brainstem (hindbrain)

Midbrain Pons Medulla Oblongata

Regions of the brain stem (superior to inferior)

Midbrain Pons Medulla Oblongata *these parts consist of many tracts of nerve fibers and nuclei

Forebrain

More complex functions

Sensory Area for taste

Near base of the central sulcus

Auditory Area

Temporal lobe Interprets hearing

Sensory speech area (wenicke's area)

Temporal/ parietal lobe Usually left hemis Understanding and formulating language

Parts of Diencephalon

Thalamus Hypothalamus

Hippocampus

Thought to be the brain center for generation of memories -temporal lobe