Transcript Spinal Cord - Northside Middle School

The Nervous System
Chapters 9 & 10
Function?
Is to RELAY messages from the INTERNAL and
EXTERNAL environments
Main Communication network of the body
Homeostasis: Balance of the body
Only great minds can read this
This is weird, but interesting!
fi yuo cna raed tihs, yuo hvae a sgtrane mnid too
Cna yuo raed tihs? Olny 55 plepoe out of 100 can.
i cdnuolt blveiee taht I cluod aulaclty uesdnatnrd
waht I was rdanieg.
The phaonmneal pweor of the hmuan mnid,
aoccdrnig to a rscheearch at Cmabrigde Uinervtisy,
it dseno't mtaetr in waht oerdr the ltteres in a wrod are,
the olny iproamtnt tihng is taht the frsit and lsat ltteer
be in the rghit pclae.
The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm.
Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but
the wrod as a wlohe.
Azanmig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt!
The organization of the Nervous system
Know for test!
2 main cell types
1.Glial ( neuralglial) -- Protect the neurons
Some say maybe more
Great research with stem cells
10 times more than neurons
Total of 6 different types
4 in the CNS
a) astrocytes: most abundant, provide barrier of blood to brain
b)Microglial—act as immune cells of CNS
c) Ependymal—ciliated—barrier between CSF and CNS—keeps csf flowing
d) Oligodendrocytes—produce myelin sheaths
2 in PNS
a) satellite—unsure of fuction
b) Schwann---forms myelin of PNS—allows it to regenerate
Find the Oligodendrocyte? Microglial? Astrocyte?
A variety of glial cells are shown. Oligodendrocytes (arrowhead)
have round medium sized nuclei and may have a few short
processes (oligo means few). Microglia (arrow) are smaller and
often have an angular nucleus and fibers originating at opposite
poles of the cell soma. Can you identify the structure curving into
the field from the upper left? It is a blood capillary with several
astrocyte processes attached
2) Neuron : The functional unit of the nervous system
Very specialized
Special characteristics
1. Extreme longevity—over 100 years
2) Amitotic—no mitosis---no new cells
3) Very high metabolic rate--The rules of 3’s
DEMANDS O2 and glucose
3 weeks without food
3 days without water
3 hours without shelter
3 minutes without air
But not three seconds without hope.
3 different types of neurons determined by # of branches
2 processes- axon &
dendrite—very rare—
retina eye, olfactory
3 or more processes
Most common
99% these
Unipolar
pseudounipolar
Begins as 2 then form
single
Mainly in ganglia of
PNS
Structure of Neurons
A)
Cell body (Soma)
2 special organelles
1.
Nissl bodies— (Chromatophilic: orderly arrangement of Rough ER)
2.
-large granular body
-contains rough ER—produces protein
-axoplasmic transport—transport of materials from cell body to
axons
Neurofibrils---long thin fibrils that give support and structure
to neurons in the cytoplasm
B)
Cell Processes ( branches)
1. Dendrite—usually multiple/cell body
-carry impulses to the cell body
2. Axon—usually only 1/cell body
-carry impulses away from cell body
United Streaming: Biologix: Nerve Impulse Conduction
End is the SYNAPTIC KNOB—
the “gap” Node of Ranvier
Some fibers are myelinated—“jumps”—Salatory Conduction
---- Much faster mostly found in the PNS
Myelinated = white matter Unmyelinated = gray matter
If not myelinated impulse must move continuously as waves--chemicals involved sodium &
potassium
PNS—Neurilemma-outer covering of Schwann cell
-Schwann cells surrounds axon--this allows repair
CNS—lacks a Schwann cell so NO regeneration--YET!!!!!
Receptor Classes
A) Exteroreceptor
External stimuli
B) Interoreceptor
internal (gut)
D) Photoreceptors
Light
E) Chemoreceptors
chemical
C) Proprioreceptors
body part relation
G) Thermoreceptors H) Mechanoreceptors
Temperature
tension and pressure
F) Pain receptors
Nerve:
Structure (pg 229) Epineurium: covering over the nerve
Fascicle:bundles of wrapped axons Perineurium: covering over fascicle
Endoneurium: wrapping around individual axons in a nerve
A connective tissue sheath called the
epineurium surrounds each nerve. Each
bundle of nerve fibers is called a
fasciculus and is surrounded by a layer of
connective tissue called the perineurium.
Within the fasciculus, each individual
nerve fiber, with its myelin and
neurilemma, is surrounded by connective
tissue called the endoneurium. A nerve
may also have blood vessels enclosed in
its connective tissue wrappings.
Nerve Impulses ( aka) Action Potenial
Reaction time
.5 –150m/sec
300mph
The 4 steps of a reaction
Irritability---
WILL BE ON TEST
Neurons respond
Conductivity---
Enable neurons to encode stimulus
into impulse
Integration--- CNS sorts impulses& interprets them
Reaction--- CNS sends its own message telling which
mucle or gland to react
Nerve Impulse Transmission
-neurons at rest have high K+ and low Na+ on inside of neuron and
Low K+ and high Na+ outside the neuron
-causes a slight – charge inside the cell and + outside
-when an impulse is conducted the permeability of the membrane changes
For Na+ ions and they rush into the cell
-this causes the polarity to change--+ charge inside the cell and
- charge outside the cell=--called Depolarization
-this section of membrane immediately recovers and Repolarizes
-However, depolarization stimulates adjacent membrane and
Depolarization continues down length of axon until it reaches the synaptic
Knob
-if a region of myelinated axon is reached the impulse is able to
jump over the myelinated region
-called saltatory conduction
-increases speed of nerve impulse
HOW IMPULSE TRANSMITTED---impulses go
from bodyspinal cordbody
Reflex arc—2-neuron arc
-consists of only 2 neurons—1 sensory
neuron
and one motor neuron—only 1 synapse
-ex. Knee-jerk reflex
-3-neuron arc
-consists of all 3 types of neurons
and 2
synapses
-withdrawal reflex
-sensory neuron interneuron
Functions of Neurons
A? Sensory-Afferent
C? Integration—
Associative or
Interneuron
B?
Motor-Efferent
The Synapse
Neurotransmitters, such as Acetylcholine, are
stored in vesicles in the presynaptic
terminal. Acetylcholine is secreted across synaptic
clefts, where it binds to the post synaptic
membrane and causes a change in the permeability
of the postsynaptic cell, which results in an
excitatory post-synaptic potential.
Neurotransmitter—between presynaptic neuron and postsynaptic neuron
different ones 5 main ones
Neurotransmitters
A)Acetylcholine—innervates skeletal muscles, slows the
heart,
-used to dilate constrict pupils in cataract surgery, reverse
affects of muscle relaxants, treat myasthenia gravis, and
alzheimer’s
-used in nerve agent sarin and in some pesticides
B)Norepinephrine—functions include increasing the rate
of contractions, acts a stress hormone by increasing
heart rate, triggering release of glucose from storage,
increase blood flow to skeletal muscle
-too much associated with schizophrenia, and too little
associated with ADHD and depression
C)Dopamine: functions include roles in cognition and behavior, motivation,
punishment and reward, sleep, mood, attention, working memory, and
learning
-too little associated with ADHD and Parkinson’s disease,
too much associated with pshychosis and schizophrenia
D)Serotonin-the “feel good" neurotransmitter
-insulin released when carbs are eaten—breakfast???
-protein containing tryptophan in conjunction with carbs
-insulin allows tryptophan to be taken into brain and used to
make
serotonin
-involved in mood, sexual desire and function, appetite, sleep, memory,
learning, temp. regulation, and some social behavior
Shortage---depression, sleep disorders, eating disorders, digestive disorders
Excess—diarrhea, vomiting, headache, rapid heart rate, serotonin syndrome
1) light
3 ways to get to release—
2) exercise
3) diet
E) Endorphins---natural painkillers in labor--Released under stress
-leads to feelings of euphoria, appetite modulation
Release of sex hormones, improved immune response, and dec
Feelings of pain
Sleep
24 hour period---circadian rhythm
REM—Rapid Eye Movement
without sleep
Sleep video 2:51
http://player.discoveryeducation.com/index.cfm?guidAssetId=69D1E39F
No Video, TV, flashing lights 1 hr before
Nervous is body’s main communication system of the body
works with the endocrine system (hormones)
Central nervous system--- brain and spinal cord
Meninges—
infected =
meningitis
Dura mater Outer-tough Dense CT
Arachnoid Transparent
Pia mater
Innermost, attaches
to SC and Braincontains b.v
Spaces-- Subarachnoid---filled with cerebrospinal fluid (CSF)
--acts as a shock absorber and helps protect against
pathogens
used in treatments---page 247--spinal tap—
collect CSF and check for substances
(pathogens, etc.)
hydrocephalus—accumulation of CSF in brain—results when CSF can’t drain
away
Epidural—introduction of an
Anesthetic into the CSF in the
Lumbar region of the spinal
column
The illustration to the left represents a post-mortem axial section of a normal lumbar spinal
canal. The vertebral body is shown at the top and the lamina of the vertebrae at the
bottom. The epidural space surrounds the dural membrane. Only the posterior portion of
the epidural space is outlined in green as this is the area of clinical interest.
Spinal Cord---Runs out of the foramen magnum
42-45 cm long (if of average height)
Gray H--- composed of gray matter—mainly cell bodies
and dendrites
-Front 2 –ventral horns
carry messages to skeletal muscle
-Rear 2 – dorsal horns
Receive and process incoming information—carry info toward the brain
Spinal Nerves--(pg 245)
8 Cervical
12 Thoracic
1 Coccygeal
5 Lumbar
5 Sacrospinal
Map of spinal nerves---- Dermatome: skin surface area supplied by
A single spinal nerve
Parts of the brain
Dissection photo
Next slide
Sheep brain
*1. cerebrum
4. cerebral aquaduct
*5. Mudulla oblongata(turn arrow)
*6. pons
*7. cerebellum
**9. spinal cord
*14. Thalamus
*15 & 21. optic chiasma
*16. Pituitary gland
*18. mammillary body
*19. pineal gland
*20. olfactory bulbs
Dissected brain
Brain --- 3 LBs on average 80-120 billion neurons Protected by skull, BBB and CSF
Proportioned to
body mass
Difference between
male and female???
Now the truth--- Male 1600 g
Female 1450g
Why? Proportioned to size
http://www.bbc.co.uk/science/humanbody/sex/add_user.shtml?users=1
Pet scans
Positron emission tomography
This brain picture shows the communication centers in the male brain (designated by the blue areas) and
the communication centers in the female brain (designated by the red areas).
One of the final frontiers is the human brain. Current research reports that we change
our brain with every conversation, every action we partake in. Our brain keeps changing
and developing well into our 80’s (current research states 80’s but it could be longer).
Just because your biological hand may have dealt you a certain brain style doesn’t mean
you can’t change, build, and reconstruct your brain. If you communicate indirectly you
can practice communicating directly with a direct speaker. If you are a direct speaker
you can work with an indirect speaker to build up your ability to speak indirectly.
Dementia
Each brain image shows the change in brain metabolism when subjects were
asked to inhibit their response to food during food stimulation compared with
when they were not told to inhibit their response. Two brain sections at different
levels of the brain are shown for each group (women, men, and women vs. men).
Top row, women: No color indicates that women had
no significant differences in brain activity between
the two conditions.
Middle row, men: Blue colored areas were
significantly less active when men were told to inhibit
their response to food than they were without
inhibition.
Bottom row, women vs. men: Orange color
indicates areas where men showed greater
decrements with inhibition than women. These
brain regions are involved in emotional
regulation, conditioning, and the motivation to
eat.
Cranial nerves
-- 12 pairs ( Page 252)
Quiz
Name & Function
I.Olfactory: sense of smell
II.Optic: vision
III.Oculomotor: eye movements
IV.Trochlear: eye movements
V.Trigeminal:face, scale, teeth sensation, chewing
movt
VI.Abducens: eye movements
VII.Facial: taste, facial muscle contractions
VIII.Vestibulocochlear:hearing,balance
IX.Glossopharyngeal: sensations of throat;
swallowing, taste, saliva secretion
X.Vagus: sensations of throat,larynx,thoracic &
abdominal organs, swallowing, voice, slowing of
heartbeat, speed up peristalsis
XI.Accessory: shoulder movts, turn head
XII.Hypoglossal: tongue movts
Development- begins about 2 weeks after fertilization
Neural plate—2 weeks 4 days—thickened plate of ectoderm in the embryo that
develops into the neural tube
1) Hindbrain—upper part of spinal cord, brain stem, and cerebellum
2) Midbrain—uppermost part of the brain stem
3) Forebrain--cerebrum
Fully developed -- 4 divisions
Hindbrain– A) Brain stem—
midbrain, pons, medulla oblongata
Midbrain-B)uppermost part of brain
stem
Forebrain- C) Cerebrum,
D) Diencephalon- hypothalamus,
thalamus, epithalmus
Ventricles—contain CSF
Gyri—ridge on the cerebral cortex
Brainstem --- 2-way—connects motor and sensory systems
from the main part of the brain to the body
3 main parts ---medulla oblongata, pons, midbrain
Medulla oblongata-3 main control centers-1.Respiration
2.Cardiac Center
3.Reflex centers of vomiting, coughing, sneezing, and swallowing
Origin to 4 cranial nerves--- IX, X, XI, XII
Pons—integral part of the brain’s pathway (connects various parts of the brain), as a
Respiration control center (inhalation initiator), maybe REM sleep and arousal
Origin to 4 cranial nerves --V, VI, VII, VIII
Midbrain-associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and
Temperature regulation
2 cranial nerves --III, IV
DIENCEPHALON--(interbrain)
thalamus—relays sensory and motor signals to the cerebral cortex,
regulates consciousness, sleep, and alertness
-switchboard that sends incoming info where it needs to go in
the brain
hypothalamus—links the nervous and endocrine systems via the pituitary
gland
-makes and secretes neurohormones that stimulate or inhibit
the secretion of pituitary hormones
-controls body temperature, hunger, thirst, fatigue, sleep, and
circadian cycles
Epithalumus—secretion of melatonin by pineal gland and regulation of
motor pathways and emotions
Cerebellum– 2nd largest part of the brain % of brain mass
controls muscle movement and coordination
works to maintain posture
acts as our balance center
-- gray matter—outer layer
--- white matter—bulk of interior
Cerebrum lobes
Cerebrum– largest part of the brain 66% of brain mass
--origin to 2 cranial nerves --I and II
Quiz
Responsible for perception, thought, decision making, primary sensory
Areas (visual, auditory, etc), and primary motor area
Quiz is a combo—P. 250
3 parts--1) Cortex---outermost layer
Makes us aware of our environment
3 areas----motor, association, and sensory
All neurons are—unmyelinated
Each side (hemisphere)
Olfactory area—involved in sense of smell
referred to as “executive suite”
2)Basal Ganglia-- InnerAssociated with voluntary motor control, procedural learning relating to routine behaviours
or habits, eye movts, and cognitive and emotional functions
3)Limbic System—functions include emotion, behavior, long term memory, and olfaction
Islands of Calleja—aids in reinforcing effects of reward-like activities
The limbic system wraps around the
brain stem and is beneath the cerebral
cortex. It is a major center for
emotion formation and processing, for
learning, and for memory. The limbic
system contains many parts, including
the cingulate gyrus, a band of cortex
that runs from the front of the brain to
the back, the parahippocampal gyrus,
the dentate gyrus, and most notably,
the hippocampus and amygdala. The
hippocampus is involved in memory
storage and formation. It is also
involved in complex cognitive
processing. The amygdala is
associated with forming complex
emotional responses, particularly
involving aggression. The limbic
structures are also connected with
other major structures such as the
cortex, hypothalamus, thalamus, and
basal ganglia.