Week 10
Homeostasis
 Internal environment (_________________) must stay the same
 Homeostasis is the _________________________________
_________________________________________________.
 For your internal environment to remain constant you must have a
1. _____________ (detect the problem)
2. _____________ (fix it)
 Example
– Oxygen concentration in blood.
• Monitor = _____________________________ in aortic arch
• Control = _____________________________
– If not enough O2 in blood,
•
•
•
•
•
chemoreceptor ______________ problem
_______________________ commands diaphragm & intercostals to work harder
Oxygen debt is soon solved
________________________ stops detecting problem
___________________________ stops trying to fix it
This controlling method is called
__________________
 Our bodies use 2 mechanisms for controlling our internal make-up.
1. ___________________________
•
and the _________________________________
2. ___________________________
•
and the _________________________________
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Nervous System
The human body is made up of 2 nervous systems.
 ____________________________________________
o ________
 _____________________________________________
o ________
Central Nervous System
 __________________________________
Peripheral Nervous System
 __________________________________
 __________________________________
PNS is divided into:
 __________________________________
o ____________________________________________
o Nerves leading to ______________________________
o Fast nerve transmission __________________________
 __________________________________
o ____________________________________________
o ____________________________________________
o Slower nerve transmission_______________________
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Autonomic Nervous System
o Controls things like ___________________________________________
_______________________________________________________________
o Divided into two halves
o ____________________________________________
o ____________________________________________
Sympathetic
 Nerves which transmit impulses during times of stress
 Speed up functions like blood pressure and heart rate…
 Nerves from spinal cord
Parasympathetic
 Nerves which transmit impulses when the body is attempting to return back to normal after a
time of stress.
 Slows heart rate and blood pressure…
 Nerves from brain.
Neurons
General Properties of all Neurons
 The basic unit of the nervous system is the _______________.
 A ______________ is a bundle of these neurons.
 Neurons are specialized to conduct an _________________________________.
All neurons have the same basic components:
 __________________ -- receive stimuli
 __________________ -- contains nucleus and cell organelles
 _______________ -- long cylinder carrying impulse to next neuron or to effector.
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_______________can be up to 1 meter in length.
 Sometimes, the axon of a neuron can have an insulating cover called a
________________________________
 white
 made up of __________________________
 speeds up impulse transmission
 appears like sausages
 the naked spaces of axon in between myelinated sections (sausages) are called
_________________________________________
 every 1 mm along the axon.
Neurons can be categorized based on their function
 _________________________________
 Brings information to the __________.
 Located in ganglia next to the spinal cord in the dorsal root.
 _________________________________
 Found only in brain and spinal cord (CNS).
 Form link between _________________ and ________________ neurons.
 __________________________________
 Carries impulses from __________ to _____________ (muscles or glands)
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The Reflex Arc
 The somatic nervous system controls all voluntary systems within the body except for
______________________.
 These are what we call _________________________.
 They protect the body quickly when presented with a stimulus that the body perceives as being
dangerous.
 Although reflex arcs send secondary signals to the brain during the reflex action, the primary
response is "hard wired" through the spinal cord.
 Certain stimuli, such as touching a hot surface, cause a reflex arc
 the nerve impulse travels
 ______________________________________________________
 ______________________________________________________
 ______________________________________________________
 result = jerk the hand away from the hot surface.
 This automatic response system allows for
__________________________________________________.
 A reflex arc must always include 5 components:
1.
____________________________________
2.
____________________________________
3.
____________________________________
4.
____________________________________
5.
____________________________________
** Create a personal mnemonic device for remembering the order of RSIME**
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Week 10 formative part 1
Pg 410 # 3 on a drawn neuron, 4
Pg 414 # 1, 2, 6, create a mnemonic device for remembering the parts of a reflex arc
Send #3, 1, and 2 to me for feedback
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Week 10 continued
Nerve Impulse
 A nerve impulse can actually be thought of as an ________________________ from one place
to another.
 This can be achieved by _______________________________________________________ in
and out of the neuron.
 ________________ and _____________________ play important roles.
 There is lots of sodium and potassium around the neuron.
 In reality, there is a proton pump that will transport _______________ into the neuron and
______________ out of the neuron.
 There are also channels that will allow certain ions to diffuse back across the membrane of the
neuron.
 _______________________________________
 _______________________________________
The Goal…

To have a _______________________________________ across the membrane.

The _______________________________________

This is achieved by having one channel open and the other closed.
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 At rest, the inside of the neuron is negative relative to the outside
 inside is said to be _______________________
 The neuron is ____________________.
 It is polarized because the inside of the neuron and the extracellular fluid are
________________________________________
 When electrical charges are separated in this way, they have the potential to do work should they
be permitted to come together.
Resting Potential Summary
 Polarization occurs because of the ___________________ _______ _____________________.
 Polarization is mainly due to 3 main factors:
1. The outward diffusion of potassium ions
2. The sodium pump is actually slightly more efficient than the potassium pump (more
sodiums out than potassiums in – approximately 3:2)
3. The presence of large diameter negatively charged anions that are stuck inside the
neuron.
The Stimulus
 Electrical, chemical, or mechanical stimulus will alter the resting potential by causing
_____________ to leak back into the neuron.
 “Sneaks” through the sodium channel.
 This changes the polarity slightly
 If the stimulus is strong enough to bring the inside to about -55 mv, a __________________ has
been reached.
 Once this occurs, the _______________ channels immediately _____________ wide and
___________________ channels ______________.
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 The rapid influx of sodium causes a momentary reversal in polarity.
 ___________________________
 Membrane potential shoots to about _________________.
 This sharp rise and fall of action potential is called a __________________.
 This could be described as a slight electrical disturbance in the neuron.
 The ______________________________________ is an electric current strong enough to
induce the collapse of the resting potential in the adjacent area of the neuron.
 As the wave of ______________________ moves along the axon, the normal polarized state is
quickly reestablished behind it.
 Must get back to ______ outside and _____ inside.
 Sodium channels ____________, and potassium channels _____________.
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Repolarization
 The sodium and potassium pumps soon reestablishes resting potential ion separation.
 The amount of time it takes to repolarize is called the ____________________________.
 approximately 1 ms (millisecond)
 During this time the axon cannot transmit an action potential no matter how great the stimulus.
 During repolarization, the rapid pumping of sodium causes a momentary
____________________________.
 Too much ____________ outside
 Inside is about _________
 Resting state is established when potassium re-enters the neuron.
Impulse Transmission
 Neurons and Impulse Transmission
 Follow the “_____________________________” principle
 a stimulus above the threshold level, whether strong or VERY strong produces the
same _________________ of signal transmission.
 More stimulus (i.e. more painful) = more impulses generated, NOT a stronger impulse.
 An impulse does not diminish in strength as it travels along a neuron.
 We already know that having a myelin insulation on an axon will __________ its impulse
transmission.
 This is because the impulse will ____________ from node to node.
 In this way, sodium and potassium do not have to undergo exchanges along the entire
length of the axon
 Sodium and potassium pumps and channels are active only at each
__________________________________________
 This is where the axon can actually exchange ions with the extra cellular fluid.
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Page 11 of 21
Week 10 formative part 2
Pg 418 # 1-4
Pg 420 # 5, 6
Pg 425 # 2, 3, 4 (send me these)
Week 11
The SYNAPSE!!
Getting the impulse from one neuron to the next.
 Adjacent neurons in a nerve fiber do not actually touch end to end.
 The junction between them is called a ________________.
 The gap is called a ________________________________.
 The gap between the terminal axon of one neuron and the dendrite of the next is about 0.02 m.
 one millionth of an inch
 When the nerve impulse (depolarizing wave) reaches the synaptic knob, it must jump to the next
neuron.
 Impulse moves from the __________________ of a pre-synaptic neuron to the _____________
of a post-synaptic neuron.
Neurotransmitters
 Each _________________________________ (terminal axon) has vesicles that will produce and
secrete ________________________________.
 When the impulse reaches the synaptic knob, the membrane surrounding the knob
becomes permeable to _________________.
 The calcium causes the vesicles to fuse to the membrane of the knob emptying their
neurotransmitters into the ____________________________.
 A _________________________________ is a chemical that will signal the next neuron’s
dendrites to send an impulse down its axon.
 Important neurotransmitters are…
 ______________________________ -- most common
 neuromuscular junctions, brain, internal organs
 usually has an _________________________ effect on post-synaptic dendrite.
 _________________________ (norepinephrine)
 same thing but involved in the __________________________ nervous system
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 HOW DOES IT REALLY HAPPEN??
 ________________________________ is released from vesicles in the pre-synaptic axon
 it diffuses across the synaptic cleft
 it lands on _________________________________ on the post-synaptic dendrite
 Its purpose is to partially _____________________ the membrane of the post-synaptic dendrite.
 This excites the __________________________________________.
 ______________________ channels on post-synaptic dendrites open
 _________________________ (charge reversal)
 action potential is achieved
 wave of depolarization spreads across __________________________ neuron
 Problem: If acetylcholine remains in the receptor site, the sodium channels will remain
open
 repeated stimulation of muscle
 Solution: _______________________________ (an enzyme released into synaptic cleft)
breaks down acetylcholine.
 Once sodium channels close, the neuron begins recovery.
 Troubles…
 Nerve gas ___________________ cholinesterase.
 the amount of acetylcholine in synaptic cleft increases with each successive nerve
impulse
 repeated stimulation of muscle
 life-threatening spasms
 The acetylcholine from one axon terminal is usually not enough to cause depolarization of the
post-synaptic neuron.
 Usually, neurotransmitters from a few different pre-synaptic knobs are needed to induce
an action potential
 This is known as _______________________________.
 Some neurotransmitters are not ____________________ but rather ______________________.
 These cause post-synaptic ______________________ channels to open fully
 _____________________________________
 more potassium will flow out (diffusion)
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 more ____________________ charges outside neuron
 Resting potential is now even more negative
 Need higher stimulus to overcome _______________ and initiate action potential
Disorders
 M.S.
 Multiple Sclerosis
 Deterioration of the _____________________________________________
 scar tissue on axon
 no impulse transmission
 impaired neural function
 loss of coordination
 tremor
 paralysis
 Nerve Damage due to injury
 If damaged neurons are covered by the thin membrane called ______________________,
regeneration is likely (only in ___________________________________________).
 No neurilemma = no chance of regeneration
 Parkinson’s Disease
 Involuntary muscle contractions
 Insufficient production of _________________________________ (a neurotransmitter)
 Alzheimer’s Disease
 loss of memory
 decreased production of _____________________________________
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Structures of the CNS and PNS
 Spinal Cord
 Brain
– runs down neck and back
– more complex functions
– coordination of
inside the spine
– receives information from
•
•
•
•
•
skin & muscles
– sends motor commands
for movement
– controls reflex activities
homeostasis
perception
movement
intellect
emotions
Central Nervous System
 _____________________________________
–
Structure
•
•
_________________________________
–
outer layer
–
consists of motor and sensory axons
–
___________________________________
___________________________________
–
inner layer
–
contains cell bodies of motor neurons and interneurons.
The Spinal Cord
•
_______________________________
–
•
•
contains cerebrospinal fluid
_______________________________
–
pass through dorsal root
–
have cell bodies in the dorsal root ganglion
____________________________________
–
leave the spinal cord through the ventral root.
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The Brain
 3 pounds
 one of the largest organs in body
 soft
 squishy
 Protected by 3 layers of membranes called _______________________________
–
Dura Mater -- outer (next to skull)
–
Arachnoid -- middle
–
Pia Mater -- inner
 Infection (and swelling) of meninges is called …
MENINGITIS
Cerebrospinal Fluid
 Surrounds the _________________________________
 Lies in between the Pia Mater and the Arachnoid layer.
–
_________________________________
–
brings nutrients, hormones and WBC to parts of brain
–
Circulates between meninges and central canal of spinal cord
–
Drains into veins
Anatomy of the Brain
 Divided into
–
_______________________________
–
_______________________________
–
_______________________________
–
Controls
• pattern & image formation
• memory
• learning
• emotions
Includes:
• ________________________________
• ________________________________
• ________________________________
Forebrain
–
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Thalamus
 Relay center for information on its way to cerebrum
– sensory information is sorted out
– sent to appropriate higher brain centers
Hypothalamus
 Regulation of _________________________________
–
source of hormones (ADH, Oxytocin - uterine contractions)
•
pituitary gland is connected to hypothalamus
–
thermostat
–
hunger
–
thirst
–
sexual response
–
mating behaviors
–
fight-or-flight response
–
pleasure / rage
–
biological clock
•
when we sleep
•
when our sex drive peaks
Cerebrum
–
2 cerebral hemispheres
•
left -- controls the _________________ side of body
–
•
right -- controls the _______________ side of body
–
•
Logical thought
Creative thought
The two halves of the brain communicate with each other through the
________________________________________
–
a thick white band of fibers
•
Outer gray matter is called ______________________________
•
each hemisphere is divided into ____________________________
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–
4 lobes in each hemisphere
•
frontal -- near the forehead
–
•
•
•
speech, personality, precise movements
temporal -- by your ears
–
hearing
–
smell
parietal-- top of your head
–
taste
–
reading
–
body position
occipital -- back of your head
–
vision
Cerebral Cortex
 Largest part of the brain
 most complex
 different parts of the cortex are in charge of different parts of the body.
Midbrain
 Small region
–

relay center between
•
forebrain & ___________________
•
forebrain & __________
Vision
–
vision is controlled in the ____________________
–
vision reflexes & some perceptual functions are controlled here
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Hindbrain
 Called the _________________
–
lower brain
–
Coordinates large-scale body movements like walking.
•
______________________________________________
•
__________________
•
____________________________________
Medulla Oblongata
 ______________________ & _______________________ functions
–
breathing, heart rate, blood pressure, vasoconstriction/vasodilatation, swallowing,
digestion, vomiting …
–
Here, motor axons from the mid and forebrain cross from one side of the CNS to the
other SIDE!!!.
•
as a result, right side of brain controls left side of body, and visa versa.
Pons
 just above medulla oblongata
 relay center between the __________________ and the _____________________
Cerebellum




Smooth coordination of ________________________
Hand-eye coordination
__________________________
________________________________________ about
– position of joints, length of muscles, visual & auditory activity
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The Peripheral Nervous System
 Nerves that leave the brain and spine
–
________________________
•
nerves that leave the brain
–
–
Lead to organs of the head & upper body
•
parasympathetic system
•
Vagus Nerve = important cranial nerve
______________________________
•
nerves that leave the spine
–
•
Lead to the whole body
sympathetic system
Antagonistic Systems
 When both the sympathetic and parasympathetic systems innervate the same effector, they are
called ________________________.
–
I.e. Heart
•
Sympathetic = _________________________
•
Parasympathetic = ______________________
Page 20 of 21
Week 11 Formative
Pg 420 # 7
Pg 425 # 5(send to me)
pg 429 # 1, 2, 3
pg 432 # 2, 3 (send #2 to me)
pg 435 #2 (send to me)
pg 441 #1-11, 13, 15-19 (send me #2,3,4,6,7,9, 10, 11,13)
When you get feedback from these questions, set up a time to write your week 10-11 test.
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