Download Outline for CNS, PNS, and ANS

Development of the Central Nervous System (CNS)
Week 2 -neural plate
Week 3 -neural groove
Week 4 -neural tube
(ice cream cone view)
1. Prosencephalon 2. Mesencephalon 3. Rhombencephalon Week 5 -brain sections
1. Telencephalon-hollow space =
2. Diencephalon -interbrain (
)
-diencephalons, thalamus, hypothalamus, epithalamus
-hollow space =
3. Mesencephalon-brain stem: midbrain
-hollow space =
4. Metencephalon-after brain
-brain stem:
-hollow space =
5. Myencephalon-spinal brain
-brain stem: medulla oblongata
-hollow space =
6. Spinal cord
-spinal cord
-spinal cord
-hollow space =
After week 5, brain begins to curve and bend because it's growing faster
than skull
Week 6
Week 13
Cerebrum (
)
Diencephalon (
)
Brain stem
midbrain (
)
pons ( )
medulla oblongata (
Spinal cord ( )
Cerebellum ( )
Birth
1. Cerebrum
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
2. Diencephalon
3. Brain stem
Midbrain
Pons
Medulla Oblongata
4. Cerebellum
5. Spinal Cord
)
FUNCTIONS OF MAJOR BRAIN AREAS
1.
Cerebral Hemispheres
A. Sensory input
B. Voluntary motor output
C. Intellect, reasoning, problem-solving
2.
Diencephelon
A. Relays information to cerebrum
B. Controls ANS
C. Emotions
3.
Brain Stem (midbrain, pons, medulla oblongata)
A. Relays information to cerebrum
B. Reflex centers
4.
Cerebellum
A. Relays info about voluntary muscles to primary motor
cortex
B. Coordinates skeletal muscles (balance, posture)
BRAIN FEATURES
I. Cerebrum features
A. left and right hemispheres – midsagittal cut
B. gyrus and convolution – part of the folds that stick up
C. fissures and sulci – depressions, deep or shallow respectively
D. parietal lobe - top
E. temporal lobe - side
F. frontal lobe - front
G. occipital lobe - back
H. longitudinal fissure – divides hemispheres
I.
transverse fissure – divides cerebrum from cerebellum
J.
lateral sulcus – divides parietal lobe from temporal lobe
K. central sulcus – divides parietal lobe from frontal lobe
L. parieto-occipital sulcus – divides parietal lobe from occipital lobe
M. precentral gyrus – convolution anterior to central sulcus
N. postcentral gyrus – convolution posterior to central sulcus
O. corpus callosum – largest commissure (connection) between the
hemispheres. Allows them to communicate.
P. primary motor area – controls voluntary muscle movements
- located in the precentral gyrus
Q. primary sensory area – receives information from voluntary
muscles. Located in the postcentral gyrus
R. fornix – small commissure (connection) between diencephalons
halves. involuntary information.
S. premotor area – memory for repetitive motor skills
T. speech or Broca’s area – lateral frontal lobe
U. visual area – occipital lobe
V. auditory area – temporal lobe
W. taste area - parietal lobe
X. olfactory area – frontal lobe
II. Diencephalon Features
A. thalamus – “gateway to the cerebrum”, relays information
B.
hypothalamus – main visceral control center in the body
- ANS, emotions, body temp, food intake,
water balance, digestion
1. pituitary gland – a main endocrine gland in body
2. infundibulum- stalk of the pituitary gland
3. mammillary body- relay for olfactory information
C.
epithalamus – found above the thalamus
1. pineal body- makes melatonin which helps regulate
sleep/wake cycles
III. Cerebellum features
A. cerebellar hemispheres – coordinates body movements
B. arbor vitae – the pattern of white matter resembling a tree
IV. Brain Stem Features
A. Midbrain features
1. corpora quadrigemina –large nuclei or group of cell bodies
a. superior colliculi – visual reflex centers (blinking)
b. inferior colliculi – auditory reflex centers(startle reflex)
B.
Pons features
1. pons means bridge and it is the bridge between the motor
cortex and the cerebellum
C.
Medulla oblongata features
1. medullary reflex centers
a. cardiovascular - cardiac and vasomotor
b. respiratory – rate and depth of breathing
c. other reflexes–sneeze, hiccup, vomit, swallow, cough
PROTECTIVE STRUCTURES OF THE CENTRAL
NERVOUS SYSTEM
I. Bone – 8 cranial bones
II. Membranes =
- functions to protect CNS and blood vessels. Also contains CSF
In order from outside in
A. ______________ – “tough mother” – thick outside membrane
B. ______________ – small space between dura and arachnoid
C. ______________ – “spider mother” –thin middle weblike membrane D.
______________ – places were CFS enters blood
E. ______________ – larger space between arachnoid and pia filled
with CSF
F. ______________ – “soft mother” – thin inner membrane that adheres
to the brain and spinal cord
PAD
III. Cerebrospinal fluid (CSF)
- functions to cushion, protect, and nourish the brain
A.________________– Makes CSF
B.________________– membrane that separates lateral ventricles
C.________________– one in each hemisphere
D.________________– connects lateral to 3rd ventricle
E.________________– around thalamus
F.________________– connects 3rd to 4th ventricles
G.________________– bordered by cerebellum
H.________________– holes by cerebellum that connect venticle CSF
to CSF in the subarachniod space
I.________________- holes by cerebellum that connect venticle CSF
to CSF in the subarachniod space
J.________________– hollow middle of spinal cord
IV. Blood Brain Barrier
1. Function –
2. Why? Fluctuations in concentrations of hormones, amino acids, and ions in
the blood would affect the neurons in the brain and cause them to fire
uncontrollably. Particularly after exercise or eating.
3. Looks like – 3 layers
A. Capillary wall - epithelium with tight junctions
B. Thick basal lamina
C. Astrocytes – hold capillary to neuron
4. Characteristics
A. Selective rather than absolute barrier
B. Nutrients (
) move by facilitated diffusion from
blood to CSF
C. Ineffective against metabolic wastes, proteins, fats, gases, most
chemicals (exceptions )
5. Exceptions
A. Choroid plexus, 3rd ventricle, and 4th ventricle – no barrier
B. Vomiting center – monitors poisons
C. Hypothalamus – regulates water balance
D. Newborns – haven’t developed yet, can’t fight toxins like
adults
SPINAL CORD
1.
2.
3.
4.
5.
6.
Begins –
Ends –
A. Conus medullaris B. Filum terminale C. Cauda equina Length – 17 inches
Width – ¾ inch (diameter of pinky finger or 5th digit)
except A. Cervical enlargement –
B. Lumber enlargement –
Protection ( same as brain)
A. Bone
B. Membranes
C. CSF
Clinical Application -
Cross-section of spinal cord
1.
2.
3.
4.
Fissures
A. Anterior median fissure –
B. Posterior median fissure –
Gray matter – butterfly-shaped
A. Location – deep to white matter
B. Commissure C. Posterior horn – Interneurons (receive info from sensory nerves)
D. Lateral horn – Autonomic motor neurons (
) send info
out to visceral organ
E. Anterior horn – Somatic motor neurons (
) send info out
to skeletal muscles
White matter
A. Location – superficial to gray
B. Posterior column – ascending tracts (
)
C. Lateral column – ascending and descending tracts
D. Anterior Column – ascending and descending tracts
PNS branches
A. Dorsal root – sensory (
) fibers
B. Dorsal root ganglion – sensory cell bodies
(motor are located in spinal cord)
C. Ventral root – motor (
) fibers
D. Spinal nerve – ventral and dorsal roots meet (mixed nerve)
Peripheral Nervous System
Nerves as organs
- cordlike organ
- consists of peripheral axons wrapped in connective tissue and surrounded by
endoneurium (loose connective tissue)
A. 2 main types of PNS nerves
1.
2.
B. 3 functional types of PNS nerves
1. Sensory nerve (
2. Motor nerves (
) – nerves that carry impulses to CNS
) – nerves that carry impulses away
from CNS
3. Mixed nerves – nerves containing both sensory and motor fibers
C. 2 locational types of PNS nerves
1. Visceral – autonomic nerves
2. Somatic – skeletal muscles
We can combine these together
S.A.
S.E.
V.A.
V.E.
Sense receptors of touch
a.
b.
c.
d.
e.
f.
g.
h.
Free dendritic endings – found - everywhere especially C.T.
- function –
Nociceptors – found - everywhere especially C.T.
- function –
Pacinian corpuscles – found – everywhere especially C.T.
- function –
Merkel discs – found - germinativum layer of epidermis
- function –
Root hair plexus – found – hair follicle
- function –
Messners corpuscles – found – dermal hairless skin,
(soles of feet, fingertips, genitalia)
- function –
Muscle spindles – found – skeletal muscles
- function –
Golgi tendon organs – found – tendons
- function –
The Spinal Reflex Arc
- reflex defined as a predictable automatic response to changes
Reflex arc components
1. Receptor of stimulus
2. Sensory neuron entering via dorsal root with cell body in dorsal root
ganglion
3. Synapse (directly with motor neuron or with interneuron)
4. Motor neuron exiting via ventral root with cell body in ventral gray
horn
5. Effector (
) responds
Spinal Nerves
31 pairs of nerves - all are mixed
- dorsal and ventral root join to make spinal nerve
A. Naming spinal nerves
- named from point of entry into/out of spinal cord
- top 7 spinal nerves located above same bone name
- rest of spinal nerve located below same bone name
____cervical spinal nerves (one more than number of bones)
____ thoracic spinal nerves
____ lumbar spinal nerves
____ sacral spinal nerves
____ coccygeal spinal nerve
Example - 3rd cervical nerve
- 5th lumbar nerve
B. Naming the plexuses
After exiting from the intervertebral foramen, branching occurs. The dorsal branch
extends to innervate skin and muscles of the back; anterior or ventral branch to
muscles and skin of the front of trunk and limbs.
With exception of the thoracic region, the anterior branch forms network (plexus)
fibers of spinal nerves and are sorted and recombined.
FINAL RESULT: although the point of origin of the spinal nerve may differ, fibers
for a particular part of the body meet in the same nerve.
1. _________________ found deep in neck from C1-4, serves skin and muscles
of head and neck, diaphragm—connects with some cranial nerves.
2. _________________ found within shoulder between neck and armpit from C5T1—serves upper extremities, parts of neck and shoulders
3. _________________ located within muscle that tilts pelvis from L1-L4—
serves part of lower extremities, external genitalia
4. _________________ found on posterior wall of pelvic cavity from L5-S4 –
serves buttocks, perineum (between pubic area and anus in both sexes), and
rest of lower extremities
Cranial Nerves
Number
1
2
3
4
5
6
7
8
9
10
11
12
Saying
Name
S/M/B
Function
CHARACTERISTIC
ALSO CALLED
EFFECTOR OR
TARGET ORGAN
# NEURONS IN PNS
TO EFFECTOR
EFFERENT
PATHWAYS
1ST NEURON IN
EFFERENT PATHWAY
2ND NEURON IN
EFFERENT PATHWAY
CONDUCTION SPEED
NEUROTRANSMITTER
EXAMPLE
AUTONOMIC N.S.
SOMATIC N.S
AUTONOMIC NERVOUS SYSTEM
CHARACTERISTIC
ALSO CALLED
FUNCTION
ORIGIN OF NERVES
LOCATION OF
MOTOR GANGLIA
NAME OF GANGLIA
LENGTH OF AXONS
BRANCHING
NEUROTRANSMITTER
NERVE FIBER
OR AXON NAME
Sympathetic
(Emergency, stress)
Parasympathetic
(Non-emergency)
EFFECT ON
ORGAN/SYSTEM
HEART
BLOOD VESSELS
RESPIRATORY
DIGESTIVE
EYE PUPILS
SKELETAL MUSCLES
URINARY
GLANDS
ARRECTOR PILI
MUSCLE
LIVER
CELLULAR
METABOLISM
MENTAL ACTIVITY
Sympathetic
(Emergency, stress)
Parasympathetic
(Non-emergency)
SHORT STRESSED SUZY HAS 2 THICK CHAINS
Short –
Stressed –
Suzy –
2–
Thick –
Chains –
*General – increase in activity to skeletal muscles, decrease in activity
to digestive system and other systems
Passive Polly thinks gangs are very “achy” and terminal
Passive –
Polly –
“Achy” –
Terminal –
*General – resting nervous system, digestion and other systems are
functioning normal, and skeletal muscle activity decreases