A fundamental premise of materialistic science holds that a complete explanation of brain function is possible in purely objective physiological and biophysical terms....in the world view of materialist science, real mental freedom to act and choose is only an illusion...The resultant view of human nature and the kinds of values that emerge are hardly uplifting. All of us would prefer to think that we are more than mere puppets... At stake are central key concepts that directly involve fundamental convictions regarding the nature of man's inner being, physical reality, the meaning of existence, and related matters of ultimate concern. When it comes to brains, remember that the simpler electric, atomic, molecular, and cellular forces and laws, though still present and operating, have been superceded by the configurational forces of higher-level mechanisms. At the top, in the human brain, these include the powers of perception, cognition, reason, judgment, and the like, the operational, causal effects and forces of which are equally or more potentent in brain dynamics than are the outclassed inner chemical forces.
-Roger Sperry (1981 Nobel prize)

NERVOUS SYSTEM

Assignment

Audesirk, Audesirk & Byers part of Chapter 38, one reference back to chapter 37

Today's musical selection
Napoleon XIV They're coming to take me away

Since metazoans have division of labor (with different organs), there must be a means of integration:
(1) hormones (covered already); and
(2) nervous system
hormones are wasteful since not all cells are target
N.S. more discreet

100,000,000,000 (100 billion) neurons (many connections [synapses])

stimulus -> organism -> response
Energy-(Receptor-Nervous System-Muscle, Gland)-Effect

Figure 38-1
TYPICAL CELL-spinal motor neuron
Dendrite, soma, axon, synapse, vesicle - integration of information

Voltage is potential difference (-70 mV inside negative), and think of "potential" in the physics sense as "potential energy" for now.

Figure E38-1
K+ is relatively more concentrated inside the cell

Figure E38-2
Na+ is relatively concentrated outside the cell

Energy (delivered by ATP) pumps these ions

Figure 38-2
The imbalance of potassium through the membrane which is selectively permeable to K+ creates the Resting potential -70 mV (inside negative)
Nerve and muscle are "excitable" (responsive, a basic property of life), and, in particular, they generate big all-or-none potentials called action potentials or spikes which travel down axons real fast.
all-or-none - binary code +55 mV

Figure E38-2
Na+ permeability increases - action potential (spike)
Channels open and close

Figure E38-3
action potential triggers the action potential ahead of it on the axon, thus it propagates

Figure 38-3
Myelin speeds up action potential to 120 m/s = 269 mph
(slower than light or electricity, but adequate considering body size)
Polio damages myelin in peripheral nervous system
Multiple sclerosis (Anette Funicello, Montell Williams, Richard Prior) damages myelin in the central nervous system

Neurochemistry

Figure 38-4
Axons carry all or none spikes - binary code of n.s.
vs. Synapse (and receptors) -graded potentials- excitation and inhibition are then integrated.
neurotransmitters are in vesicles at synapse
Receptor molecules- very important-

Figure E-38-5
here the receptor is a channel,

Figure 37-3
but there are receptors which work like the membrane receptors for hormones which work through a second messenger system.

Figure E38-5
here are excitatory and inhibitory synapses
Here's how they work
EPSP=excitatory postsynaptic potential, IPSP= inhibitory postsynaptic potential

Transmitters: (like hormones, more discreet) amines, peptides
also amino acids, nucleotides, nitric oxide, carbon monoxide
Synthesis, breakdown, reuptake, diffusion

Figure E 38-6
(health watch box)
Transmitter, location -drug (disease)
Cocaine blocks reuptake of norepinephrine, dopamine and serotonin
Alcohol stimulates receptors for GABA (inhibitory neurotransmitter) blocks receptors for glutamate (excitatory)
Dopamine neurons die in Parkinson's disease, a common health problem usually affecting people over 50, usually not genetic, causes tremor, lose emotion (affect), stone (expressionless) face, Mohammed Ali, Michael J. Fox, Pope
Acetylcholine neurons die in Alzheimer's
Serotonin -Prozac used for depression, the "soma" (Aldus Huxley - Brave new world) of psychiatry
Ecstacy (MDMA) increases serotonin
Noradrenalin (sympathetic nervous system), caffeine & amphetamine (speed) potentiate
Endorphins, Enkephalins (peptide) opiates
opium, poppy, morphine, codeine, heroin, narcotic analgesics,
strategy of look for receptors, what is "endogenous" transmitter
Adicrion can follow where the disruption caused by the drug upsets the body's endogenous mechanism which becomes inadequate by itself.

Organization of the nervous system


Figure 38-10
stimulus - response, e.g. reflexes like the pain-withdrawal reflex

Figure 38-9
Gray- cells, synapses; White-myelinated axons
reflex overseen by volition
afferent - toward the CNS, efferent- away from the CNS

Figure 38-7
Vertebrate CNS (brain and spinal cord)
- PNS - Sensory
Motor systems- Somatic for Striated (Skeletal) muscle
peripheral n.s. has sensory and motor portions. Motor has somatic and autonomic. Autonomic has sympathetic and parasympathetic.

Figure 38-8
Autonomic (for smooth muscle and glands) - Sympathetic Parasympathetic (Details are discussed extensively)

Figure 38-12
Brain function (these statements will be oversimplifications)
medulla - fundamental functions like respiration
cerebellum - motor control
hypothalamus - motivation
thalamus - relay for sensory signals

Figure 38-13
limbic system - smell, emotion, learning, very complex

Figure 38-14
cerebral cortex
localization of function- like motor, vision, audition, speech

some fundmental points:
Brain - O2 dependence (CPR)
glucose dependence (insulin shock)
no mitoses (why stroke is so damaging)

Questions used in 2007 and 2008 related to this outline

The action potential occurs
(a) when the voltage is -70 mV inside negative.
*(b) when sodium channels open.
(c) when cocaine blocks the reuptake of norepinephrine.
(d) when neurosecretion from the pituitary toward the hypothalamus occurs.
(e) when an inhibitory postsynaptic potential (IPSP) causes hyperpolarization.

Cyclic adenosine monophosphate (cAMP) is a second messenger
(a) when steroid hormones regulate transcription.
(b) when myelin speeds up the action potential.
(c) when potassium goes through membrane potassium channels.
(d) mediating all-or-none spikes.
*(e) when neurotransmitters affect G protein-coupled receptors.

What happens to a person who has Parkinson's disease?
*(a) Dopamine neurons die.
(b) Endorphin production increased.
(c) Prozac neurons die.
(d) Serotonin production increases.
(e) Norepinephrine is reuptaken.

Neurotransmitter substances are located in (A) and affect receptors in (B).
(a) (A) axons; (B) dendrites.
*(b) (A) synaptic terminals; (B) dendrites.
(c) (A) G protein-coupled receptors; (B) vesicles.
(d) (A) Schwann cells; (B) myelin.
(e) (A) white matter; (B) gray matter.

In addition to polio (what?) is a disease of myelin?
*(a) multiple sclerosis
(b) amyotropic lateral sclerosis (ALS)
(c) myopia
(d) schizophrenia
(e) heroin addiction

The resting potential is
(a) called the threshold.
(b) 50 mV inside positive.
(c) called the EPSP.
*(d) 40 to 90 mV inside negative.
(e) -70 volts.

What statement below best describes action potentials?
(a) An action potential is called an excitatory postsynaptic potential.
(b) An action potential would go too fast if myelin were not present to slow it down.
(c) Action potentials are responsible for "runner's high."
(d) Action potentials are mediated by potassium being so high outside cells.
*(e) An action potential is all-or-none.

The autonomic nervous system
*(a) controls smooth muscle and influences heart rate.
(b) is localized in the white matter of the brain.
(c) is the sensory input to the brain.
(d) mediates the knee jerk reflex.
(e) connects to striated muscle.

The brain structure responsible for controlling the subconscious functions of salt and water homeostasis, sex drives, and hunger is the
(a) cerebral cortex.
(b) cerebellum.
(c) thalamus.
(d) medulla.
*(e) hypothalamus.

Questions used in 2002 relating to this outline (and other outlines)

The autonomic nervous system
*(a) is composed of the sympathetic and parasympathetic nervous systems.
(b) is localized in the gray matter of the brain.
(c) is the sensory input to the brain.
(d) mediates the knee jerk reflex.
(e) mediates respiration.

Multiple sclerosis is a disease that
*(a) scars central nervous system myelin.
(b) decreases transmission by dopamine.
(c) is treated by Prozac.
(d) causes hallucinations.
(e) would prevent action potentials to specific muscles.

At the postsynaptic membrane of the dendrite or cell body, the synaptic electrical potential
(a) is all-or-none.
(b) is mediated by the sodium-potassium pump.
(c) propagates faster if Schwann cells are present.
(d) moves directly from the presynaptic cell since the cytoplasm of the two cells is contiguous.
*(e) are either excitatory or inhibitory and graded (of variable size) potentials.

The brain structure responsible for controlling the subconscious functions of salt and water homeostasis, sex drives, and hunger is the
(a) cerebral cortex.
(b) cerebellum.
(c) thalamus.
(d) medulla.
*(e) hypothalamus.

What changes across the cell membrane during the action potential?
(a) lipids
(b) water
*(c) voltage
(d) ATP
(e) proteins

Afferent neurons
*(a) include those from the muscle stretch receptor involved in the knee jerk reflex.
(b) carry impulses away from the central nervous system.
(c) are myelinated by oligodendrocytes and reside in the central nervous system.
(d) include the spinal motor neuron.
(e) are part of the autonomic motor output.

Myelin is part of the
(a) the male reproductive system.
(b) the cell walls of fungi.
(c) the immune system.
*(d) the nervous system.
(e) the anterior pituitary complex.

What disorder can impair breathing by interrupting the axons between the medulla and the chest?
(a) Parkinson's disease
(b) laryngitis
*(c) polio
(d) emphysema
(e) Lesch-Nyhan syndrome

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