REVIEW SLIDES

NOTE: Disclaimer: students may find typos/mistakes in these reviews. If you spot them, please feel free to make a change and then email the instructor the corrected Power Point. Disclaimer: these slides are not intended to substitute for exam preparation. Finding a mistake does not exempt students from knowing the material.

Chapter 7 The Nervous System

Which of the following best describes the function of the nervous system? a. protection, thermoregulation b. regulation of other body systems c. secretion of regulatory molecules called hormones d. movements of the skeleton

Which of the following best describes the function of the nervous system? a. protection, thermoregulation b. regulation of other body systems c. secretion of regulatory molecules called hormones d. movements of the skeleton

_______________ disease is caused by a degeneration of the dopaminergic neurons of the substantia nigra.

_Parkinson’s__ disease is caused by a degeneration of the dopaminergic neurons of the substantia nigra.

Which division of the nervous system innervates involuntary effectors?

Which division of the nervous system innervates involuntary effectors Which division of the nervous system innervates involuntary effectors? Autonomic nervous system

The membrane of resting nerve cells is more permeable to ____________ ions than __________ ions. a. sodium, potassium b. calcium, potassium c. potassium, sodium d. chloride, potassium

The membrane of resting nerve cells is more permeable to ____________ ions than __________ ions. a. sodium, potassium b. calcium, potassium c. potassium, sodium d. chloride, potassium

The average cell has a resting potential of ___________________ (provide a range of mV)

The average cell has a resting potential of __-65 to -85 mV_____ (provide a range of mV)

Injured CNS axons do not regenerate, whereas injured PNS axons do. True False

Injured CNS axons do not regenerate, whereas injured PNS axons do. True False

______________ cells form the myelin sheath in the PNS, whereas __________________ form the myelin sheath in the CNS.

Schwann cells form the myelin sheath in the PNS, whereas oligodendrocytes form the myelin sheath in the CNS.

Somatic motor neurons are responsible for both __________ and voluntary control of skeletal muscles.

Somatic motor neurons are responsible for both _reflex__ and voluntary control of skeletal muscles.

____________________ is produced by autoimmune attack mediated by T cells on the myelin sheaths in the CNS.

Multiple sclerosis__ is produced by autoimmune attack mediated by T cells on the myelin sheaths in the CNS.

____________________ is produced by autoimmune attack, mediated by T-cells, on the myelin sheaths of the PNS. This produces rapid onset of symptoms that include muscle weakness (which can dangerously affect the muscles of breathing) due to dysfunction of somatic motor axons, and cardiac and blood pressure problems due to dysfunction of autonomic axons.

Guillain-Barre syndrome is produced by autoimmune attack, mediated by T-cells, on the myelin sheaths of the PNS. This produces rapid onset of symptoms that include muscle weakness (which can dangerously affect the muscles of breathing) due to dysfunction of somatic motor axons, and cardiac and blood pressure problems due to dysfunction of autonomic axons.

Ion channels that open in response to depolarization are called

Ion channels that open in response to depolarization are called voltage-gated.

What is the difference between an action potential and an EPSP?

What is the difference between an action potential and an EPSP? Action potentials are not summed; EPSPs are summed Action potentials occur on Axons and EPSPs occur on dendrites and cell bodies (see table in book p. 187)

Describe an action potential  

Depolarization of an Axon

Describe the all-or-none law  

Describe the all-or-none law The amplitude (size) of action potentials is always the same, regardless of the strength of the depolarization stimulus (beyond threshold)  

Because action potentials look like spikes, they are often called _____________ potentials.

Because action potentials look like spikes, they are often called _____spike___ potentials.

Because of the all-or-none characteristic of action potentials, stronger stimuli do NOT result in signals of __________________ amplitude.

Because of the all-or-none characteristic of action potentials, stronger stimuli do NOT result in signals of ____greater____ amplitude.

Stronger stimuli affect action potentials by increasing their __________________.

Stronger stimuli affect action potentials by increasing their _frequency__.

As the intensity of stimulation increases, more and more axons will become activated. This process is called ___________________.

As the intensity of stimulation increases, more and more axons will become activated. This process is called recruitment.

Name two ways that neurons respond to stimuli of greater and greater strength.  

Name two ways that neurons respond to stimuli of greater and greater strength. 1) Action potentials fire with increasing frequency 2) More and more axons are activated. (recruitment)  

Name the two types of refractory period of an action potential

Name the two types of refractory period of an action potential Absolute refractory period Relative refractory period

The __________________ refractory period can be overcome by a second strong stimulus.

The ______relative_ refractory period can be overcome by a second strong stimulus.

Where on a neuron is an action potential first produced?  

Where on a neuron is an action potential first produced? Action potentials are produced at the initial segment of the axon. (Axon hillock)

Where on a neuron is an EPSP or IPSP first produced?

Where on a neuron is an EPSP or IPSP first produced? Dendrites and cell bodies

How long is an axon?

How long is an axon? Axons vary in length from a few millimeters to a meter!

Axons can form many branches called _____________________.

Axons can form many branches called collaterals___.

Axons are covered in myelin with open spots called ___________________.

Axons are covered in myelin with open spots called Nodes of Ranvier.

EPSPs and IPSPs can be “summed,” which means that their relative strengths can be added up to determine whether they will reach the threshold required to trigger a(n) ___________________.

EPSPs and IPSPs can be “summed,” which means that their relative strengths can be added up to determine whether they will reach the threshold required to trigger a(n) action potential.

When we say that EPSPs are “graded,” we mean that they can be of varying _____________, unlike action potentials, which are all-or-none.

When we say that EPSPs are “graded,” we mean that they can be of varying magnitude, unlike action potentials, which are all-or-none.

Because EPSPs have no refractory period, they are capable of ________________; therefore, another stimulation can result in an increased amount of depolarization.

Because EPSPs have no refractory period, they are capable of summation; therefore, another stimulation can result in an increased amount of depolarization.

This graph shows the _______ nature of EPSPs.

This graph shows the graded nature of EPSPs.

FOR YOUR INFORMATION

Describe events at the synapse that lead to the release of a neurotransmitter.

Release of Neurotransmitter See notes for this slide Docking involves a SNARE complex of proteins that bridge the vesicle membrane and the plasma membrane. The SNARE proteins include one in the vesicle membrane (synaptobrevin-2) and two anchored in the plasma membrane (syntaxin and SNAP-25). When an action potential arrives at the presynaptic axon terminal, depolarization opens the Ca+2 channels. When Ca2+ enters the cell, it binds to a protein called synaptotagmin that serves as a Ca2+ sensor Vesicles containing neurotransmitter are docked at the plasma membrane by three SNARE proteins. The Ca2+ synaptotagmin complex displaces part of SNARE, and the vesicle fuses. Forms a pore to release the NT Neurotransmitter diffuses across the synapse, where it binds to a specific receptor protein. The neurotransmitter is referred to as the ligand. This results in the opening of chemically regulated ion channels (also called ligand-gated ion channels). The neurotransmitter (ligand) binds to a receptor in the postsynaptic membrane

Summary of Neurotransmitter Action

Drugs that bind to and thereby activate receptor proteins are called __________________, whereas drugs that bind to and thereby reduce the activity of receptor proteins are ________________.

Drugs that bind to and thereby activate receptor proteins are called agonists, whereas drugs that bind to and thereby reduce the activity of receptor proteins are antagonists.

Muscarinic acetylcholine receptors are NOT found on the surfaces of skeletal muscle. They are found on _______________, ______________ and ______________ cells.

Muscarinic acetylcholine receptors are NOT found on the surfaces of skeletal muscle. They are found on cardiac muscle, smooth muscle and glandular cells.

Describe the action of ACh at a muscarinic receptor

Describe the action of ACh at a muscarinic receptor Muscarinic (5 subtypes of receptor) (blocked by atropine) Heart Beta gamma complex binds to K+ channels, opens them, K+ diffuses out  IPSP Smooth muscle of stomach Alpha subunit dissociates, binds to K+ channels, closes them, K+ stays inside cells  depolarization  stomach contractions

MUSCARINIC Ach Receptors Require G-Proteins In the heart, K+ channels are opened by the beta-gamma complex, creating IPSPs (hyperpolarization) that slow the heart rate. In the smooth muscles of the stomach, K+ channels are closed by the alpha subunit, producing EPSPs (depolarization) and the contraction of these muscles. Binding of acetylcholine opens K+ channels in some tissues (IPSP) or closes K+ channels in others (EPSP). Heart: K+ channels open, creating IPSPs  heart rate slowed Smooth muscle: K+ channels close, creating EPSPs  smooth muscles contract

Describe the action of ACh at a nicotinic receptor

Describe the action of ACh at a nicotinic receptor Nicotinic (blocked by curare) (see next slide) Somatic motor neurons Nicotinic  excitatory

BINDING OF ACETYLCHOLINE (LIGAND) TO ITS RECEPTOR ACETYLCHOLINE CAN BIND TO ITS RECEPTOR, WHICH IS ALSO AN ION CHANNEL Notice that 2 acetylcholines must bind

Table 9.6

CH 7 Describe the action of epinephrine at a beta-adrenergic receptor

Monoamines use G-protein Coupled Channels THIS IS A SECOND MESSENGER SYSTEM Norepinephrine, like Acetylcholine, is used as a neurotransmitter in the CNS and PNS. Sympathetic neurons of the PNS use norepinephrine as their neurotransmitter at their synapse with smooth muscle, cardiac muscle, glands. . This is a BETA ADRENERGIC receptor.

Table 9.4

What is meant by the term “retrograde neurotransmitter”?

What is meant by the term “retrograde neurotransmitter”? “retrograde” means that the neurotransmitter is released from the postsynaptic neuron and diffuses back to the presynaptic neuron.

Explain the steps at the synaptic bulb (terminal bouton) that result from an action potential and lead to the release of a neurotransmitter. Start with 1) Action potential sent to the axon terminus. End with 6) release of neurotransmitter into synaptic cleft. 1-Action potential sent to the axon terminus. 2 3 4 5 6-Release of a neurotransmitter into synaptic cleft

Explain the steps at the synaptic bulb (terminal bouton) that result from an action potential and lead to the release of a neurotransmitter. Start with 1) Action potential sent to the axon terminus. End with 6) release of neurotransmitter into synaptic cleft. 1 - Action potential sent to the axon terminus. 2 - Opening of voltage-gated Ca2+ channels. 3 - Entry of Ca2+ and binding to sensor protein (forming synaptotagmin-Ca2+ complex) 4 - Interaction between complex and synaptic vesicles containing neurotransmitter 5 - Exocytosis of synaptic vesicles 6 - Release of a neurotransmitter into synaptic cleft

CH 7 Describe endocannabinoids

Describe endocannabinoids CH 7 Describe endocannabinoids Compounds with effects similar to those of the active ingredient in marijuana (THC) Bind to the same receptors as THC Lipids, which are acting as neurotransmitters Not stored in vesicles, but rather are released from membrane May be retrograde neurotransmitters

Epinephrine, dopamine, norepinephrine, acetylcholine are known as excitatory neurotransmitters because they ___________ the likelihood that the post-synaptic cell will fire an action potential.

Epinephrine, dopamine, norepinephrine, acetylcholine are known as excitatory neurotransmitters because they _increase___ the likelihood that the post-synaptic cell will fire an action potential.

GABA and glycine are known as inhibitory neurotransmitters because they __________________ the likelihood that the post-synaptic cell will fire an action potential.

GABA and glycine are known as inhibitory neurotransmitters because they __decrease____ the likelihood that the post-synaptic cell will fire an action potential.

The disease multiple sclerosis is characterized by destruction of CNS myelin sheaths and the formation of hardened scars.

The disease __________________is characterized by destruction of CNS myelin sheaths and the formation of hardened scars.

In contrast to the all-or-none amplitude of an action potential, excitatory post-synaptic potentials (EPSPs) are

In contrast to the all-or-none amplitude of an action potential, excitatory post-synaptic potentials (EPSPs) are graded.

Some drugs are called Monoamine oxidase (MAO) inhibitors. MAO inhibitors have proven useful in the treatment of depression, as well as of panic disorder, anxiety and others. Which of the following is the best description of their mechanism of action? MAO inhibitors block the _________________________ of neurotransmitters such as dopamine, epinephrine and norepinephrine.

Some drugs are called Monoamine oxidase (MAO) inhibitors Some drugs are called Monoamine oxidase (MAO) inhibitors. MAO inhibitors have proven useful in the treatment of depression, as well as of panic disorder, anxiety and others. Which of the following is the best description of their mechanism of action? MAO inhibitors block the ____breakdown___ of neurotransmitters such as dopamine, epinephrine and norepinephrine.

GABA is a neurotransmitter which has _________________ effects on postsynaptic neurons due to its opening of ______________ channels.

GABA is a neurotransmitter which has __inhibitory___ effects on postsynaptic neurons due to its opening of chloride ion (Cl-) channels.

_________________________ is caused by degeneration of dopaminergic neurons in the substantia nigra.

Parkinson’s disease is caused by degeneration of dopaminergic neurons in the substantia nigra.

The binding of norepinephrine to its beta-receptors causes the dissociation of G-proteins. In some cases, the alpha G-protein subunit then binds to ____________________, leading to the production of ___________________.

The binding of norepinephrine to its beta-receptor causes the dissociation of G-proteins. In some cases, alpha G-protein subunit then binds to _adenylate cyclase_, leading to the production of _cAMP___. cAMP then activates a protein kinase, which opens ion channels.

CHAPTER 3 Describe Huntington’s disease

CHAPTER 3 Huntington’s disease is a neurodegenerative disorder. Results in a deficiency of GABA-releasing neurons, which results in uncontrolled movements. Inherited as a dominant gene Caused by CAG repeats in the huntingtin gene GABA is an inhibitory neurotransmitter.