Download Nervous System

Anatomy
Lecture
Nervous
Brain:
1.
2.
3.
4.
5.
6.
and Physiology
Outline
System-1
Bio-111
Principal Parts and Coverings
The principal parts of the brain are the brain stem (medulla oblongata, pons and midbrain),
cerebrum, and cerebellum.
The brain is protected by cranial bones, cranial meninges and cerebrospinal fluid.
The cranial meninges are continuous with the spinal meninges and are named the dura mater,
arachnoid and pia mater.
The brain contains cavities called ventricles which communicate with one another, with the
central canal of the spinal cord, and with the subarachnoid space.
Cerebrospinal fluid is formed primarily by the choroid plexus, found in the ventricles. It
circulates through the ventricles, the central canal and the subarachnoid space.
Cerebrospinal fluid protects the brain by serving as a shock absorber. It also delivers
nutritive substances from the blood and removes waste materials.
BRAIN
1.
2.
3.
4.
5.
6.
Largest and most complex of all of the nervous structures.
Centrally located within the cranium extending to the spinal column
Functions to
a. screen and evaluate incoming impulses
b. storage of information or retrieval
c. formulating decisions for responses
In the male 1400 grams; in the female 1250 grams
Most rapid growth within 1-5 years with a steady decline to age 20 when it ceases to grow.
Comprised of nerves
a. those fibers of the brain and the spinal cord with a common origin and destination is
referred to as a tract
b. band of fibers joining the opposite parts of the brain or spinal cord are referred to as a
commissure.
MAJOR DIVISIONS
I. Forebrain
A. Cerebrum
B thalamus
C. hypothalamus
D. pons
E. medulla oblongata
F. cerebellum
CEREBRUM
1.
2.
3.
4.
5.
6.
Comprises 7/8 of the brain in weight
consists of two distinct cerebral hemispheres separated by the central longitudinal fissure.
Contain the highest centers
a. sensory perception
b. motor control
c. memory
d. association
e. thought
f. personality
Comprised of a mixture of white and gray matter. The outer layer is the cerebral cortex is
comprised of gray matter.
Within the gray matter most of the brain is white matter with isolated masses of gray matter
called the basal ganglia
The white matter is comprised of fibers which form the ascending and descending tracts in the
cerebrum and areas in the spinal cord.
a. projection tracts - found above and downward linking the cortex with other parts of the brain
and the spinal cord. These also function to connect and transmit impulses of gyri of the same
hemisphere.
b. Association - these are found from the front of the cerebrum to the posterior which connect
areas of the cortex on the same side.
c. commissural - connects the right and left cerebral hemispheres found specifically at the
corpus callosum and the posterior commissure.
FISSURES AND CONVOLUTIONS
1. There are wrinklings and folding of the cerebral surface called convolutions.
comprised of
a. gyrus - protruding ridges
b. sulcus - depressions or grooves
These are
2.
3.
4.
5.
Central Longitudinal Fissure - separates partially the right and left cerebral hemisphere to the
point of the corpus callosum. There is a connection within a band of commissural fibers
Transverse Fissure - separates the cerebrum from the cerebellum
Central sulcus (fissure of Rolando) - separates the frontal from the parietal
Lateral fissure - lateral sulcus separates the temporal from the parietal
LOBES
A. Frontal
B. Parietal
C. Occipital;
D. Temporal
CEREBRAL CORTEX
1.
2.
Our entire personality is stored in the outer cerebral cortex - less than 1/4 inch
Cortex is elaborately broken down into mapped areas designated for specific functions.
called Brodman's Cytoarchitectural Areas (map).
These are
Parietal Lobe
a. receives information from
1. cutaneous receptors
2. muscular receptors
3. visceral receptors
b. each area of the general sensory area receives stimuli from specific parts of the body.
c. Its functions is to exactly localize the points where the sensations originated. The
thalamus localizes generally.
c. receives information from the thalamus
d integrates and interprets sensations
e. determines size and shape, texture without looking
f. establishes relative relationships
g. stores past experiences
Occipital Lobe
a. medial occipital
b. receives sensory information from eyes
c. interprets size and shape and color
d. relates present to past experiences; recognition and evaluation
Temporal Lobe
a. superior temporal
b. interprets basic characteristics of sound , i.e. pitch and rhythm
c. determines the mode of sound - speech, music, noise
d.. translates words into thoughts
MOTOR AREAS
1. The primary motor area is in the frontal lobe (4).
2. Control of specific muscle of groups for specific regions in the opposite side.
3. The areas correspond to the primary sensory areas.
Responsible for
1. Concerned with learned motor activities of complex and sequential nature
2. Yields a sequential contraction of muscles, i.e. writing.
3. controls skilled movements
4. control voluntary eye scanning i.e. such as looking at an index
Language Areas - Speech
1. This is the chief characteristic which separates us from all living organisms
2. Several regions are responsible
a. Motor Speech Area - in the frontal motor cortex involved in the actual physical movements
associated with speech
b. Temporal Lobe - concerned with the choice of thoughts to be expressed
c. Parietal Lobe - choice of words to be sued
d. Premotor Cortex - Broca's area - (44) involved with the actual word formations
3.
Speech begins with the development around the age of 3 with the left cerebral hemisphere
dominating. This is also the same time that handedness develops and the two are intimately
involved with one another.
ASSOCIATION REGIONS
1. Comprised of association tracts
2. interconnects the sensory and motor areas
3. occupies the lateral regions of the occipital, parietal, temporal and frontal lobes
4. concerned with
a. memory
b.
c.
d.
e.
f.
g.
emotions
judgments
will
reasoning
personality
intelligence
BASAL GANGLIA
This region of the brain, which is the dispersed isolated regions of gray matter within the cerebral
cortex is concerned with the following general functions
a. gross unconscious movements
b. muscle tine for specific movements
c. face and jaw movements
d. pupillary changes
e. piloarrection
f. changes in temperature, BP and respiration
g. emotional responses to fear and rage.
THALAMUS
1. Lies beneath the corpus callosum and 3rd ventricle
2. egg shaped massed of gray matter
3. central relay station of the brain
4. interconnects the cerebral cortex and spinal cord.
filtered through the thalamus
All sensory information, except smell are
FUNCTIONS:
1. all information analyzed before being relayed to the appropriate region of the cerebral cortex.
2. motor cortex impulses also enter the thalamus before entering the cord.
3. Monitors all visual and auditory reflexes
4. Functions as the crude awareness center with the cortex filling in the fine details
5. exaggeration provokes sensations of pleasure or pain even without the cortex.
HYPOTHALAMUS
1. comprises 1/300th of the brain mass
2. Vital for physical and emotional states
3. Gray mattter mass below the thalamus
4. Sensory fibers bring messages from the thalamus, cortex and the brainstem
5. Motor fibers link the hypothalamus to the thalamus, brainstem and the cord.
6. Functions as the central monitoring and control center.
AUTONOMIC NERVOUS SYSTEM
1. controls all autonomic functions through the regulation of the sympathetic and parasympathetic
nervous systems
2.. Controls heart rate and blood pressure. Stimulate causes increases in heart rate and BP at the
anterior region; the posterior hypothalamus causes decreases in heart rate and blood pressure.
3. The anterior hypothalamus contains sympathetic fibers and the posterior region contains
parasympathetic fibers
4. Controls the coordination of maintaining normal body temperature. Excessive heat causes
activation of the ANS causing dilation of the blood vessels; cold causes constriction.
5.
Sensitive to sodium and calcium ions; increases in NA ion increase temperature; increases in
calcium ions decrease temperature
6. Functions is regulation of food intake and GI activity through two centers
a. hunger - lateral
b. satiety - medial
The hunger centers are primarily stimulated by decreases in sugar in the blood plus amino acids
and fats.
7. Post meal satiety centers function through the mediation of a hormone - arenterin - released by
the intestines to signal satiety.
8. Controls peristalsis ands gastric secretions.
9. Contains osmoreceptors sensitive to water balances in the blood stream. Increases in osmotic
pressure (lack o water) cause the release of ADH TO ACTIVATE THE KIDNEY TUBULES TO REABSORB
WATER.
10. Contains the thirst center.
11. It is responsible for sleeping and wakefulness. Stimulation of certain regions provoke
wakefulness, alertness and excitement. Stimulation of other regions causes sleepiness and actual
sleep.
12. Dorsal stimulation activates sexual stimulation.
13. Numerous endocrine functions with the release of numerous releasing factors which activate the
pituitary gland.
14.
Controls a wide range of emotional states:
a. anger
b. fear
c. pain
4. pleasure
LIMBIC SYSTEM
Limbic means border. It describes the brain structures that lie in the BORDER region between the
hypothalamus and the cerebral cortex. The HYPOTHtALAMUS is the central element to the Limbic System.
This is an integrated system controlling the emotional aspects of behavior related to survival.
FUNCTIONS
It controls the behavior of
1. love-hate
2. envy-selfishness
3. altruism
4. revenge
5. subjectivity
Comprised of the
1. hypothalamus
2. thalamus
3. hippocampus
4. amygdyloid nucleus
1.
2.
3.
The limbic system colors thoughts with emotions
Controls emotional homeostasis
Recognizes equilibrium disturbances:
1. hunger or sex drive
2. danger or threat
3. worry or disappointment
4. Recognition enables higher centers to restore equilibrium
5. Can cause a clashing of rational decisions with emotional prompting, I.E. FEAR OF HEIGHTS CAN BE
OVERCOME.
6. If a stimulus causes neither reward not disappointment, it is hardly remembered. With reward or
punishment the response becomes progressively reinforced yielding a string memory
HIPPOCAMPUS
Functions in
a. long term memories
b. evaluation of new experiences from past events
c,. removal erases all memory
d. activation can elicit rage and passivity
MEMORY
DEFINED:
the ability to recall information established via sensory impulses.
a. SHORT TERM
1. no permanent imprint
2. phone numbers
3. presence of reverberating neuronal circuits
4. duration depends upon the number of neurons in circuit.
b. LONG TERM
1. permanent or persistent retention
2. not via reverberating circuits since they will cause neuronal fatigue.
4 some short term signal can be converted to long term if reverberated enough to cause an engram
5. The storage of information is related to RNA synthesis where specific proteins are synthesized
for each memory stored.
6. Recalling memory destroys the protein, but retains the mRNA template.
7. Involves the hippocampus and all association centers of the brain
RETICULAR FORMATION
1.
Found throughout the brain stem and involves the medulla, pons and parts of the diencephalon.
The collection of neuron are called the reticular formation.
2. It begins at the upper end of the cord an extends to:
a. upward through he central portion of the thalamus
b. into the hypothalamus
c. adjacent areas of the hypothalamus
3.
Contains both sensory and motor neurons
Function
1. The reticular formation is intrinsically excitable via the brain the spinal cord.
2. Excitability is held in check from the basal ganglia and cerebral cortex
3. Destruction of the basal ganglia or higher cortical centers causes rigidity of the muscles
Reticular Activating System
1. Human exhibit a 25 hrs circadian rhythm
2. Sleep ad wakefulness alternate, sleep being preceded by neuronal fatigue
3. sleep is caused by a decreased transmission of nerve impulses.
4. Activation of the cortex is thought to be related to the reticular formation.
5., Stimulation of regions of the reticular formation causes increased cortical activity which causes
arousal. This is called the reticular activating system.
Arousal Reaction
1. 'RAS stimulated from sensory input from the cord, cerebellum and the cortex.
2. RAS activation sends impulses to the thalamus then to the specific regions of the cerebral cortex.
This results in arousal
3. Following arousal there is continued activation through the feedback circuits within the cortex.
4. The RAS maintains feedback with the cord which sends impulses to the muscles ----> movement ----> propioceptors ----impulses to the cortex ------>reactivation and reinforcement of the RAS.
5. The feedback maintains the RAS which maintains the cortex which brings about consciousness.
Consciousness
There are varying levels
1. alert
2. attentive
3. relaxed
4. non-attentive
2. Dependent upon the number of operating circuits
3. Discriminates novel stimuli from familiar ----->focus
Sleep
1. Inactivation of the RAS system
2. Several Levels from NREM to REM
NREM
I. relaxed; regular respiration, normal pulse, thought active and easily awakened
II. harder to awaken; dream fragments; eyes may roll
III. very relaxed; temperature and pressure drop; approximately 20 minutes after sleep
IV.
REM or Deep sleep; responds slowly if awakened; sleep walking may occur
In a 8 hour sleep pattern a person goes from I - IV NREM sleep several times. Post IV one enters
into REM sleep for approximately 1.5 hours.
REM
1. increase in respiration with irregularity
2. increase in pulse with irregularity
3. blood pressure fluctuates
4. dreams occur
5. post REM descends to III ---->II
NREM and REM alternate at approximately 900 minute cycles
REM can last from 5-50 minutes
Infants 50% of sleep is REM
Adults 20% us REM
CEREBELLUM
1.
2.
3.
Part of the hind brain
Convoluted; mixture of gray and white matter with gray matter on the outside
White matter arranged in pattern known as the arbor vitae
Functional Aspects
1. Whenever motor cortex directs the contraction of muscle by means of impulses within the
corticospinal tracts
2. Duplicate set of instructions is relayed through the pons and cerebellum
3. As soon as those specific muscles contract, muscle spindles, joint receptors and other peripheral
receptors transmit a flow of information to the same area in the cerebellum
4. This information tells the cerebellum where each body part is at each moment.
5. Cerebellum compares the higher brain centers intention with the actual performance and corrects
if necessary
MEDULLA OBLONGATA
1.
2.
3.
4.
This is a continuation of the upper portion of the spinal cord.
Lies superior to the foramen magnum and inferior to the pons
Contains all ascending and descending tracts that communicate between the cord and the brain.
The tracts constitute the white matter of the medulla and some of the tracts cross within the
medulla. These are called pyramidal tracts or corticospinal tracts
MEDULLARY REFLEX CENTERS
1. cardiac center - regulates heart rate and force of contraction
2. Medullary rhythmicity center - adjusts basic breathing patterns
3. Vasomotor center - regulates the diameter of the blood vessels
4. Non-vital - includes swallowing, coughing, hiccuping, laughing and sneezing.
5. also contains carbon dioxide chemoreceptors.
PONS VAROLII
1.
2.
Means bridge and lies directly above the medulla
Connects the spinal cord with the brain and parts of the brain with one another. Accomplished
with two groups of fibers
a. transverse - connect with the cerebellum through the middle peduncles
b. longitudinal - belong to the motor and sensory tracts connecting the cord with the medulla with
the upper brain stem.
3. Contains the pneumotaxic and apneustic centers for breathing regulation. The pneumotaxic
inhibits inspiration and allows expiration. The apneustic allows for sustained inspiration
MENINGES
1. These are a series of 3 separate coverings to the brain and the spinal cord.
2. Contains CSF as do the ventricles of the brain.
outer - dura mater
middle - arachnoid layer
inner - pia mater
3. The dura mater is attached to the periosteum and the pia mater adheres to the outer cortex.
denticulate ligament attaches the pia mater to the arachnoid layer to prevent dislodging.
G.
1.
2.
3.
4.
H.
The
Medulla Oblongata: Anatomy and Physiology
The medulla oblongata is continuous with the upper part of the spinal cord and contains portions
of both motor and sensory tracts.
The reticular formation is a part of the medulla which functions in consciousness and arousal
from sleep.
The medulla contains nuclei that serve as reflex centers for the regulation of heart rate,
respiratory rate, vasoconstriction, sneezing, coughing, hiccuping and vomiting. The first three
are considered vital reflexes.
The medulla also contains nuclei of origin for cranial nerves VIII and XII.
Pons: Anatomy and Physiology
1.
The pons is located superior to the medulla. It connects the spinal cord with the brain and
links one part of the brain with one another by way of tracts.
2. The pons relays nerve impulses related to voluntary skeletal movements from the cortex of the
cerebrum to the cerebellum.
3. It contains the nuclei for cranial nerves V-VII and a branch of cranial nerve VIII.
4. The reticular formation of the pons contains the pneumotaxic and apneustic centers which control
respiration.
L. Brain Lateralization (Split-Brain Concept)
1.
2.
3.
Recent research indicates that the two hemispheres of the brain are not bilaterally symmetrical,
either anatomically or functionally.
The left hemisphere is more important for right-handed control, spoken and written language,
numerical and scientific skills and reasoning.
The right hemisphere is more important for left-handed control, musical and artistic awareness,
space and pattern perception, insight, imagination, and generating mental images of sight, sound,
taste and smell.
Anatomy
Lecture
Nervous
and Physiology
Outline
System-2
C.
Bio-111
Neurotransmitters [enzyme]
1. acetylcholine [acetylcholinesterase]
2. norepinephrine
[monoamine oxidase]
[caetchol-O-methyl transferase]
D. Potentials
1. excitatory postsynaptic (EPSP)
2. Inhibitory postsynaptic (IPSP)
E. Neuromodulators
1. CNS neuropeptides
2. enkephalins
3. endogenous morphine
4. glycine
5. gamma amino butyric acid (GABA)
F. Synaptic Circuits
1. divergent
2. reverberating
3. parallel
4. convergent
VI.
Reflex Arc
definition
Components
1. sensory receptor
2. sensory neuron
3. internuncial neuron?
4. motor neuron
5. effector
a. myotactic
b. pilomotor
c. secretory
C. Classes
1. superficial
2. deep
3. visceral
4. pathological
D. Subclasses
1. flexion
2. extension
3. scratch
E. Circuit
1. ipsilateral
2. contralateral
3. monosynaptic
4. polysynaptic
5. Knee jerk
6. withdrawal
F. Examples
1. pupillary
2. knee jerk
3. withdrawal
4. oculocardia
5. laughter
6. swallowing
7. vomiting
8. coughing
G. Inherent
1. grasping
2. Babinski
3. marrow
4. rooting
5. light reflex
A.
B.
VII. CNS Ventricles
A. Lateral (1 & 2)
a. Foramen of Monroe
B. 3rd Ventricle
a. Cerebral Aqueduct
C. 4th Ventricle
a. Foramen of Lushka
b. Foramen of Magendie
D. Central Canal
VIII. Spinal Cord
A. Extensions
B. Spinal Nerves
a. 8 cervical pairs
1] cervical plexus
2] brachial plexus
b. 12 thoracic pairs
1] white ramus
5 lumbar pairs
1] lumbosacral plexus
d. 5 sacral pairs
e. 1 coccygeal pair
C. Structure
1. white matter
a. columns (apl)
2. gray matter
a. horns (apl)
c.
ANATOMY
LECTURE
NERVOUS
AND PHYSIOLOGY
OUTLINE
SYSTEM-3
BIO-111
I. BRAIN STRUCTURE
A. FASCICULUS
B. FUNICULUS
C. ENDONEURIUM
D. PERINEURIUM
E. EPINEURIUM
II. MAJOR BRAIN DIVISIONS
A. FOREBRAIN
1. CEREBRUM
2. DIENCEPHALON
A. THALAMUS
B. HYPOTHALAMUS
B. MIDBRAIN
1. CORPORA QUADRIGEMINA
C. HINDBRAIN
1. PONS
2. MEDULLA OBLONGATA
3. CEREBELLUM
III. CEREBRUM
A. FISSURES
1. CENTRAL LONGITUDINAL
2. CENTRAL SULCUS (FISSURE OF
3. FISSURE OF ROLANDO
4. PARIETO-OCCIPITAL FISSURE
B. TRACTS
1. PROJECTION
2. ASSOCIATION
3. COMMISSURAL
CORPUS CALLOSUM
A. FORNIX
B. GENU
C. ROSTRUM
D. ANTERIOR COMMISSURE
E. POSTERIOR COMMISSURE
IV. CEREBRAL ASSOCIATION AREAS
A. GENERAL SENSORY AREA
B. SOMESTHETIC ASSOCIATION AREA
C. PRIMARY VISUAL AREA
D. VISUAL ASSOCIATION AREA
E. PRIMARY AUDITORY AREA
F. AUDITORY ASSOCIATION AREA
G. PRIMARY GUSTATORY AREA
H. PRIMARY OLFACTORY AREA
I. GNOSTIC AREA
V.
CEREBRAL MOTOR AREAS
A. PRECENTRAL GYRUS
B. PREMOTOR AREA
C. FRONTAL EYEFIELD AREA
D. LANGUAGE/SPEECH AREA
E. ASSOCIATION AREAS
1. MEMORY
2. EMOTIONS
3. JUDGEMENTS
4. WILL
5. REASONING
6. PERSONALITY
7. INTELLIGENCE
F. BASAL GANGLIA
1. GROSS UNCONSCIOUS MOVEMENTS
2. MUSCLE TONE
3. FACE/JAW MOVEMENTS
4. PUPILLARY CHANGES
5. PILOARRECTION
6. TEMPERATURE/ BP CHANGES
7. EMOTIONAL RESPONSES TO ANGER
A. CAUDATE NUCLEUS
SYLVIUS)
G.
B. LENTIFORM NUCLEUS
C. AMYGDALA
BRAIN LATERALIZATION
VI. DIENCEPHALON
A. THALAMUS
B. EPITHALAMUS - PINEAL GLAND
C. HYPOTHALAMUS
1. ANS
2. HEART RATE, BP AND RESPIRATION
3. BODY TEMPERATURE
4. GI ACTIVITY
5. SATIETY AND HUNGER
6. HORMONES
7. THIRST CENTER
8. SLEEPING AND AWAKEFULNESS
9. SEXUAL STIMULATION
10. ANGER AND FEAR
11. PLEASURE AND PAIN
ANATOMY
LECTURE
NERVOUS
AND PHYSIOLOGY
OUTLINE
SYSTEM-4
BIO-111
VII. LIMBIC SYSTEM
A. COMPONENTS
1. HYPOTHALAMUS
2. THALAMUS
3. HIPPOCAMPUS
4. AMYGDALA
B. CONTROLS BEHAVIOR OF:
1. LOVE-HATE
2. ENVY-SELFISHNESS
3. ALTRUISM
4. REVENGE
5. SUBJECTIVITY
6. COLORING OF EMOTIONAL THOUGHTS
7. RATIONAL DECISION MAKING
C. HIPPOCAMPUS
1. RAGE AND PASSIVITY
2. LONG TERM MEMORY
3. EVALUATION OF EXPERIENCES
4. SHORT-TERM MEMORY ( WHAT?)
5. ENGRAM FORMATION
VIII. RETICULAR FORMATION
A. COMPONENTS
1. MEDULLA
2. PONS
3. DIENCEPHALON
B. RETICULAR ACTIVATING SYSTEM (RAS)
1. AROUSAL REACTION
2. CONSCIOUSNESS
3. SLEEP
A. NREM
B. REM
IX. CEREBELLUM
A. STRUCTURE
B. PEDUNCLES
1. SUPERIOR
2. MIDDLE
3. INFERIOR
C. FUNCTION
X.
MEDULLA OBLONGATA
A. FUNCTION
B. STRUCTURE
C. REFLEX CENTERS
1. VITAL
2. NON-VITAL
XI PONS VAROLII
A. STRUCTURE
B. REFLEX CENTERS
1. APNEUSTIC
2. PNEUMOTAXIC