Physiology Unit 4

Front 1

CNS/PNS
1. The CNS is composed of which parts?
2.The PNS is composed of which parts?
3. Describe "PNS → CNS → PNS → Effectors"

Back 1

CNS/PNS
1) Brain & spinal cord.
2) Cranial nerves & spinal nerves.
3) CNS receives impulses from PNS, processes the impulses & sends impulses to PNS; the PNS directs responses to the original impulses received by the CNS.

Front 2

Neuron Classification
1. _____ neurons conduct impulses to the CNS.
2. _______ neurons conduct impulses away from the CNS (Somatic Motor & Autonomic Motor).
3. ______ connect sensory neurons & motor neurons; are located entirely inside the _______.

Back 2

Neuron Classification
1) Sensory (Afferent).
2) Motor (Efferent).
3) Association (Interneurons); CNS.

Front 3

Nervous System
1. What are the only two types of cells in the nervous system?
2. What is the function of neurons.
3. What is the function of neuroglia?
4. Which of these two are more common? How many times more.

Back 3

Nervous System
1) Neurons & neuroglia (glia cells).
2) Neurons make, send & receive messages (no mitosis).
3) Neuroglia support the neurons (mitosis).
4) Neuroglia are 5X more common than neurons.

Front 4

Neurons
1. How do neurons recieveand transmit information?
2. What is neuron structure?
3. Clusters of cell bodies in CNS =______
4. Clusters of cell bodies in PNS = _____.
5. Axons interconnecting CNS regions = _____
6. What do dendrites do?
7. What do axons w/ collaterals do?
8. What are Nissl Bodies?

Back 4

Neurons
1)By responding to stimulations, sending electrochemical impulses, releasing chemical messages (neurotransmitters)
2) A cell body w/ nucleus, dendrites & axon w/ collateral branches.
3) Nuclei (nucleus).
4) Ganglia (ganglion).
5) Tracts (tract).
6) Receive information & send it to cell body.
7) Send impulses away from cell body toward axon terminal.
8) rER of cell body cytoplasm.

Front 5

Neurons
1. Extreme axon length (2-3ft.) requires _____________ to move materials in axoplasm.
2. Define Axoplasmic flow.
3. Define Axonal transport.
4. Name two substances that use axonal transport.

Back 5

Neurons
1) Specialized transport systems.
2) 1-way movement towards axon terminal through rhythmic contractions.
3) 2-way movement using microtubules (neurofibrils).
4) Viruses & toxins move through the CNS (herpes, rabies, tetanus toxin).

Front 6

Neurons
1. Define pseudounipolar.
2. Define bipolar.
3. Define multipolar.
4. PNS has _______ to myelinate axons.

Back 6

Neuron
1) A cell body sits along side a single process (sensory neurons).
2) A dendrite & axon arise from opposite ends of cell body (retinal, olfactory).
3) Many dendrites & one axon (motor neurons).
4) Schwann cells.

Front 7

Axon Regeneration
1. If PNS axon is cut the distal part of the axon ______.
2. _______ survive & form a regeneration tube that releases chemicals to attract the growing axon.
3. Axon regeneration Occurs much more easily in the ___ than the ___.

Back 7

Axon Regeneration
1) Degenerates.
2) Schwann cells (regeneration tube guides the re-growing axon to the synapse).
3) PNS; CNS (Oligodendrocytes of CNS produce proteins that inhibit axon re-growth).

Front 8

Neuroglia
1. Define Ependymoma.
2. CNS has _____,_____,____ & ____.
3. ______ myelinate several CNS axons; __________ maintain Cerebrospinal Fluid (CSF) flow; _________ are phagocytic; _______ provide a blood-brain barrier.

Back 8

Neuroglia
1) A tumor that arises from the ependyma.
2) Oligodendrocytes, ependymal cells, microglia & astrocytes.
3) Oligodendrocytes; ependymal cells; microglia; astrocytes.

Front 9

Astrocytes
1. Astrocytes are the most common glia cell; helps _______ to form the blood-brain barrier.
2. What does the blood brain barrier do?
3. Capillaries of the brain are less leaky than ____.
4. What do astrocytes prevent?

Back 9

Astrocytes
1) Capillaries.
2) Allows only some compounds to enter the brain.
3) Capillaries in the body.
4) Unwanted materials (microbes/viruses) from entering a neuron (also prevents certain drugs from entering)
(L-dopa → barrier → dopamine)

Front 10

Myelination
1. How Schwann cells myelinate axons?
2. What is a Myelin sheath?
3. What is Neurilemma?
4. What is White matter?
5. What is Grey matter?
6. What is a Node of Ranvier?

Back 10

Myelination
1) By wrapping around the axon many times (up to 1mm of axon).
2) Schwann cell plasma membrane.
3) Schwann cell cytoplasm.
4) CNS location containing myelinated axons.
5) CNS location containing unmyelinated axons, dendrites & cell bodies.
6) An uncovered space between two Schwann cells (AP only occurs here).

Front 11

Myelination
1. List attributes of unmyelinated axons.
2. List attributes of unmyelinated axons.
3. After the axon hillock reaches threshold & fires AP, its _____ influx depolarizes adjacent regions to threshold: generating a new AP; process repeats all along the axon, so AP amplitude is always same (conduction is _____ because every ion gate on the axon must open & close in sequence)
4. What can not flow across myelinated membrane surface? (No AP can occur under the myelin sheath)
5. In a myelinated axon an AP at one node can depolarize the next node to threshold. This is very fast because AP skips from node to node; ↓gates to open (↓ ion movement); ↓pumping needed (↓ion movement). What is another name for this process?

Back 11

Myelination
1) Slow conduction; high energy use; 80-90 m.p.h.; many Na+/K+ pumps; more ATP used.
2) Fast conduction; low energy use; 250+ m.p.h.; few Na+/K+ pumps; less ATP used.
3) Na+; slow
4) Ions.
5) Saltatory conduction.

Front 12

Membrane Potential
1. What kind of cells can discharge their RMP quickly through rapid changes in permeability to ions.
2. How is MP measured?
3. Define depolarization.
4. Define Repolarization.
5. Define Hyperpolarization.
6. Define and describe what happens during an AP.

Back 12

Membrane Potential
1) Excitable cells (neurons & muscle cells do this to generate & conduct impulses).
2) By placing 1 electrode inside of the cell & 1 outside of the cell.
3) MP becomes ↓negative.
4) MP returns to the RMP.
5) MP becomes more negative than RMP.
6) An AP is a wave of depolarization & repolarization that sweeps along the axon membrane from hillock to axon terminal; depolarization of the membrane through Na+ inflow (+40mV), followed by repolarization through K+ outflow (–65mV).

Front 13

Membrane Ion Channels
1. How do MP changes occur?
2. Closed channels have ______ that allow them to be opened.
3. What opens voltage-gated (VG) channels?
4. 1 type of ___ channel is always open, another type is ____ & is closed in a resting cell; ___ channels are VG (closed in resting cells)

Back 13

Membrane Ion Channels
1) Through membrane channels (gates).
2) Molecular gates.
3) Depolarization.
4) K+; VG; Na+.

Front 14

Mechanism of AP
1. Describe the actions involved with step 1 of an AP.
2. Describe the actions involved with step 2 of an AP.
3. What kind of diffusion do depolarization and repolarization use?
4. After an AP, Na+/K+ pumps move Na+ from in to out & move K+ from out to in. This is done through _______ transport.

Back 14

Mechanism of AP
1) Depolarization:
-At threshold, VG Na+ channels open
-Na+ is driven inward (to ICF) by its concentration gradient (↑ to ↓) & electrostatic gradient (+ to –)
-This is depolarization & opens more channels along the axon membrane (positive feedback)
-MP changes from –65mV to +40mV
-Na+ channels (gates) close
2) Repolarization:
-VG K+ channels open (MP = +40mV)
-Concentration gradient (↑ to ↓) & electrostatic gradient (+ to –) drives K+ outward (to ECF)
-Repolarizes axon from +40mV to –65mV (RMP)
3) Simple diffusion (passive transport, w/no ATP needed).
4) Active (w/ ATP needed).

Front 15

Action Potentials
1. When MP reaches ______, an AP is irreversibly fired.
2. Positive feedback opens more & more ______ channels.
3. Shortly after opening, ___ channels close & become inactivated (refractory period) until _______.
4. What causes more action potentials to be produced?
5. Why is there a refractory period?

Back 15

Action Potentials
1) Threshold;
2) Na+.
3) Na+; repolarization.
4) Increased stimulus intensity.
5) The refractory period occurs when the membrane cannot produce another AP because Na+ channels are inactivated (only 1 AP is produced at a time).

Front 16

Synapse
1. What is a synapse?
2. What are the two types of synapses?
3. Which type of synapses are more common?
4. What happens in an ES?
5. Name 4 properties of a CS?

Back 16

Synapse
1) Functional connection between a neuron (presynaptic) & another neuron or a muscle cell (postsynaptic).
2) Electrical & chemical synapses.
3) Electrical synaptic transmission is rare. Chemical synaptic transmission is via neurotransmitters (NT).
4) Depolarization flows from presynaptic into postsynaptic cell through channels called gap junctions; formed by connexin proteins & found in smooth muscle, cardiac muscle, brain & glia cells.
5)
A) Synapse separates axon terminal of the presynaptic cell from the postsynaptic cell.
B) Neurotransmitters (NT) are in synaptic vesicles of the presynaptic cell.
C) Vesicles fuse with the axon terminal membrane of the presynaptic cell after Ca2+ enters the ICF from the ECF; release NT by exocytosis into the synapse.
D) Amount of NT released depends upon the frequency of action potentials.

Front 17

Synaptic Transmission
1. What mineral is involved in a synaptic transmission, and what role does it play?
2. What moves across the synapse & binds to receptor proteins (postsynaptic membrane)?
3. Name three things that happen after chemically-regulated ion channels on the post-synaptic membrane open.
4. What 2 types of messages can summate?
5. If MP in the postsynaptic cell reaches threshold (–50mV)- What happens next?

Back 17

Synaptic Transmission
1)
A) AP travels down the axon membrane to depolarize the axon terminal membrane
B) Opens VG Ca2+ channels in axon terminal
C) Ca2+ moves from out to in by concentration & electrostatic gradients (↑ to ↓) & (+ to –)
D) Ca2+ forms cofactors to activate enzyme systems & trigger exocytosis of synaptic vesicles & release NT into the synapse.
2) Neurotransmitters.
3)
A) Depolarizing channels (Na+/K+) cause EPSP (excitatory postsynaptic potential).
B) Hyperpolarizing channels (Cl–) cause IPSP (inhibitory postsynaptic potential).
C)EPSP moves to VG channels in the postsynaptic cell @ the axon hillock & can form an AP.
4) Excitatory postsynaptic potential & inhibitory postsynaptic potential.
5) An AP is generated at the axon hillock of the post-synaptic cell; the AP moves down the axon membrane to the axon terminal

Front 18

NTs and Channels
1. What is the most common neurotransmitter in the body?
2. Where is it used?
3. Is it excitatory or inhibitory?
4. Name 2 properties of Ligand-Operated Channels.
5. Nicotinic ACh Channel: what forms it, and name 3 properties/steps associated with it.
6. A receptor is a 1-subunit protein & is not part of the ion channel. It activates channel indirectly through ______.
7. What happens in Muscarinic ACh Channel?

Back 18

NTs and Channels
1) AcetylCholine.
2) Used at: neuromuscular junctions, brain, Autonomic Nervous System.
3) Can be excitatory or inhibitory depending on the receptor subtype (nicotinic or muscarinic).
4)
A) Ion channel & NT receptor are on the same protein.
B) Channel opens when ligand (NT) binds to the receptor.
5)
A) Channel formed by 5 subunits; 2 subunits have ACh binding sites
a) Opens when 2 ACh bind to the receptor; permits diffusion of Na+ into & K+ out of the postsynaptic cell.
b) Inflow of Na+ occurs 1st & outflow of K+ occurs 2nd through the same channel.
c) Makes EPSP ( –65mV to 0mv to –65mV).
6) G-proteins.
7)
A) Binding of 1 ACh activates G-protein message, which travels to the ion channel.
B) Opens some K+ channels, causing hyperpolarization.
C) Closes other channels, causing depolarization.

Front 19

NTs and Associated Terminology
1. What de-activates ACh?
2. Cholinergic neurons use ____ as a NT.
3. Somatic motor neuron synapse on skeletal muscle is called the _______________.
4. ACh produces an __________ (like an EPSP)

Back 19

NTs and Associated Terminology
1) Acetylcholinesterase.
2) ACh.
3) Motor end-plate (neuromuscular junction).
4) End-plate potential. (Opens VG channels at the motor end-plate. Causes a muscle contraction (curare blocks ACh action at the NMJ))

Front 20

Monoamines
1. How do MAs work?
2. List 3 MAs.
3. What is the chemical name for Serotonin, and what AA is it derived from?
4. What 2 things can inactivate MAs?
5. How do MAOI work?
6. Serotonin is involved in regulation of __________.
7. SSRI (Serotonin-Specific Reuptake Inhibitor) includes the antidepressants: Prozac, Zoloft, & Paxil; all block ______________ (prolonging the action of serotonin at the synapse) → ☺
8. Dopamine is involved in_________.
9. Degeneration of dopamine motor neurons causes ________.
10. In ___, NE is a sympathetic division (fight vs. flight) neurotransmitter.
11. In ___, NE affects general level of arousal; amphetamines & other stimulants (caffeine) stimulate NE pathways (↑sympathetic division response). Caffeine blocks __________ activity. _____ blocks cAMP. cAMP carries the NE message…(caffeine therefore stimulates the NE message).

Back 20

Monoamines
1) Receptors activate G-protein cascade to affect ion channels.
2) Serotonin (☺), norepinephrine (NE), dopamine (☺).
3) 5-hydroxytryptamine; tryptophan.
4) Presynaptic reuptake, or breakdown by MonoAmine Oxidase (MAO).
5) MAO inhibitors are antidepressants because they allow ↑monoamine levels in the synapse for long periods of time.
6) mood, behavior, appetite, & cerebral circulation. (LSD is a serotonin mimic)
7) Reuptake of serotonin.
8) Motor control & emotional reward system (involved in addiction).
9) Parkinson's disease (↓ dopamine). (Schizophrenia (↑dopamine) is treated by anti-dopamine drugs (dopamine blocking-agents). (Cocaine blocks dopamine reuptake, which ↑dopamine at the synapse → ☺)
10) PNS.
11) CNS; phosphodiesterase; Phosphodiesterase

Front 21

Amino Acid Neurotransmitters
1. Glutamic acid & aspartic acid are _______ excitatory neurotransmitters (like ACh).
2. ____ is an inhibitory NT. -Opens Cl– channels (hyperpolarize).
3. ______ blocks glycine receptors (promotes EPSP by preventing an IPSP).
4. Gamma-aminobutyric acid is most common inhibitory NT in the _____ (opens Cl– channels)
5. What 2 substances mimic GABA?
6. Neuropeptides cause a wide-range of effects; not thought to open ______. Many are _____ & are involved in learning & neural plasticity.
7. ______ promotes satiation following meals.
8. What blocks Substance P receptors?
9) _____ and ______ are natural opiates (analgesics), like β-endorphin (runner’s high)Effects are blocked by ______, an opiate antagonist (blocking agent).
10. What is the most common neuropeptide, and what does it do?
11. What is similar to tetrahydrocannabinol (THC) in marijuana (appetite stimulator)?
12. NO (nitric oxide) & CO (carbon monoxide) are gaseous NTs. Act through ___ second messenger system. NO causes _____________; CO regulates _______.

Back 21

Amino Acid Neurotransmitters
1) CNS.
2) Glycine.
3) Strychnine.
4) brain.
5) Gamma-butyrolactone & Gamma-hydroxybutyrate.
6) ion channels; neuromodulators.
7) Cholecystokinin
8) Analgesics.
9) Endorphins; enkephalins; naloxone.
10) Neuropeptide Y; appetite stimulator.
11) Endocannabinoids. (Have analgesic effects (painkiller for cancer patient))
12) cGMP; smooth muscle relaxation; the hypothalamus.

Front 22

Summation and EPSP vs IPSP
1. Define temporal summation.
2. Define spatial summation.
3. Define Excitatory Post-Synaptic Potential.
4. Define Inhibitory Post-Synaptic Potential.

Back 22

Summation and EPSP vs IPSP
1) EPSPs from one neuron, can summate at a divergent synapse; the message moves from one location to several locations.
2) EPSPs from several neurons, can summate at a convergent synapse; the message moves from several locations to one location.
3) Graded in magnitude; has no threshold; causes depolarization; summates; has no refractory period; forms action potentials.
4) Graded in magnitude; has no threshold; causes hyperpolarization; summates; has no refractory period; inhibits action potentials.