Lecture 9: Nervous System

Front 1

What are glial cells and what is one essential role of it?

Back 1

Glia nourish neuron, insulate the axons of neurons, and regulate the extracellular fluid surrounding neurons.

Glial cells are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain and peripheral system.

One of the essential roles of glia is in the nervous system development. In embryos, cells called radial glia forms tracks along which newly formed neurons migrate from the neural tube, the structure that gives rise to the CNS.

Later, glia called astrocytes participate in formation of blood-brain barrier, a specialization of the walls of brain capillaries that restricts the entry of most substances from the blood in the CNS.

Front 2

Central Nervous System vs Peripheral Nervous System

Back 2

*The peripheral nervous system consists of nerve cells that lie outside the brain case or spinal vertebrae. Sensory receptors detect changes in the external environment (visual, auditory, olfactory, sensory, etc.) and communicates them to the CNS.

The central nervous system integrates information arriving from the PNS, processes this information to generate behavior, which it communicates back to the PNS. The CNS consists of the brain and spinal cord.

Front 3

Describe the parasympathetic nervous system.

Back 3

The parasympathetic nervous system's general function is to control homeostasis and the body's rest and digest response.

It originates in the Spinal cord and medulla.

Its neuron pathways are longer and slow.

Hint 3

Front 4

Describe the sympathetic nervous system.

Back 4

The sympathetic nervous system's vernal action is to mobilize the body's fight-or-flight response.

Originates in the spinal cord, thoracic, and lumbar spinal cord.

Its neurons are very short and it is a faster system.

Hint 4

Front 5

The organism encounters stress. What happens?

Back 5

Stress causes the hypothalamus to send signals through nerve cell to the spinal cord to more nerve cells, to the adrenal gland. The adrenal gland will secrete epinephrine. This is an example of sympathetic response.

Front 6

What does is mean for a neuron to be afferent?

Back 6

Neurons that receive information from our sensory organs (e.g. eye, skin) and transmit this input to the central nervous system are called afferent neurons.

Front 7

When Na+ ion channels open in a neuron, Na+ floods the inside of the membrane. Is this depolarization or hyperpolarization?

Back 7

Depolarization. The inside of the membrane is become less negative with the influx of Na+ ions.

Front 8

True or False: Color blindness is a X-recessive trait?

Back 8

True. This is why Males have a higher chance of being color blind since the male has only one X chromosome.

Hint 8

Front 9

What is the cerebrum?

Back 9

The cerebrum controls skeletal muscle contraction is the center for learning, emotion, memory, and perception.

Front 10

How do we study the function of each part of the brain?

Back 10

- Measuring activity

- Analyzing the consequences of patients with lesions in specific areas of the brain.

- Making lesions in model organisms

Front 11

Where does the generation of emotion occur?

Back 11

Limbic system. The brain structure that is most important for emotional memory is the amygdala.

Hint 11

Front 12

The somatosensory receptors provide information about

Back 12

- Touch

- Pain

- Pressure

- Temperature

- Position of muscle and limbs

Front 13

Explain the effects of cocaine, heroin and nicotine on inhibitory neurons.

Back 13

Front 14

What is neuronal plasticity?

Back 14

This capacity for the nervous sys-tem to be remodeled, especially in response to its own activ-ity, is called neuronal plasticity.

If you don't use it, you lose it.

Front 15

What is associative learning? Give an example.

Back 15

In associative learning, animals associate one feature of their environment with another.

For example, a white-footed mouse will avoid eating caterpillars with specific colors after a bad experience with a distasteful monarch butterfly caterpillar​

Front 16

Classical conditioning vs operant conditioning

Back 16

- Classical conditioning is a type of associative learning in which an arbitrary stimulus is associated with a reward or punishment

- Operant conditioning is a type of associative learning in which an animal learns to associate one of its behaviors with a reward or punishment

Front 17

Dendrites

Back 17

A typical neuron has numerous highly branched extensions called dendrites. Together with the cell body, the dendrites receive signals from other neurons.

Front 18

Axon

Back 18

A neuron also has a single axon, an extension that transmits signals to other cells.

Axons are often much longer than dendrites, and some, such as those that reach from the spinal cord of a giraffe to the muscle cells in its dfeet.

Front 19

In the image, what is being magnified? Describe it's function.

Back 19

Each branched end of an axon transmits information to another cell at a junction called a synapse.

The part of each axon branch that forms this specialized junction is a synaptic terminal.

Front 20

Complete this sentence:

In most neurons, the concentration of _______ is higher inside the cell, while the concentration of ______ is higher outside .

Back 20

1) K+

2) Na+

Front 21

Complete this sentence:

The sodium-potassium pump uses _____ as energy to _____ transport ______ out of the cell and ______ into the cell.

Back 21

1) ATP

2) Actively

3) Na+

4) K+

Front 22

How many Na+'s ions does the sodium-potassium pump outside the cell? How about K+?

Back 22

The sodium-potassium pump transpors three (3) Na+ out of the cell for every two (2) K+ that it transports in.

Front 23

True or False. The equilibrium potential of K is positive and Na is negative.

Back 23

False.

The equilibrium potential of K is negative and Na is positive.

Front 24

What are myelin sheaths?

Back 24

The electrical insulation that surrounds vertebrate axons.

Front 25

Describe the process of a chemical synapse. Start with the arriving action potential.

Back 25

1) An Action potential arrives, depolarizing the presynaptic membrane.

2) The depolarization open voltage-gated channels, triggering an influx of Ca2+.

3) The elevated Ca2+ concentration causes synaptic vesicles to fuse with presynaptic membrane, releasing neurotransmitter into the synaptic cleft.

4) The neurotransmitter binds to ligan-gated ion channels into the postsynaptic membrane. In this example, binding triggers opening, allowing Na+ and K+ to diffuse through.

Hint 25

Front 26

What is spatial summation?

Back 26

Spatial summation is a way of achieving an action potential in a neuron with input from multiple presynaptic cell. Spatial summation is the algebraic summation of potentials from different areas of input, usually dendrites.

Front 27

What is temporal summation?

Back 27

Temporal summation is where a high frequency of action potentials in the presynaptic neuron elicits post synaptic potentials that overlap and summate with each other.

Hint 27

Front 28

Describe the flow of information in the nervous system

Back 28

Sensor - sensory input - integration - motor output - effector

Front 29

Resting potential

Back 29

Membrane potential when no signal is being sent. This is established by ion pumps and channels

Front 30

What is the source of membrane potential in a neuron?

Back 30

The buildup of negative charge within a neuron

Front 31

Non-gated channel

Back 31

Responsible for resting membrane potential. Ions permeable to non-gated channels may move freely across the membrane

Front 32

Voltage gated channels

Back 32

Responsible for generation and propagation of action potential. Outgoing signal from the neuron

Front 33

Chemically gated channel

Back 33

Responsible for synaptic potentials, incoming signals to the neuron.

Front 34

What is the equilibrium potential for Na+ and K+?

Back 34

Na+ = 60mVK+ = -90mV

Front 35

What does "increasing permeability of Na+" mean? "Increasing permeability of K+" ?

Back 35

Na+ channels open, Na+ in, inside of cell becomes more positive, starts to depolarize.K+ channels open, K+ rushes out of cell, inside of cell becomes more negative, starts to hyperpolarize (this also occurs during "undershoot")

Front 36

What is an action potential?

Back 36

Occurs following depolarization that shifts membrane potential sufficiently. Action potentials have constant magnitude. Arise following Na+ voltage gated channels open and cause inside of cell to become increasingly positive, if reaches "threshold" an action potential occurs.

Front 37

Describe the phases of an action potential

Back 37

1. Resting state: Na+/K+ gated channels closed, ungated channels maintain the resting potential2. Depolarization: Stimulus opens some Na+ channels, Na+ flows into cell, depolarization occurs (inside of cell less negative)3. Rising: Depolarization has opened most of the Na+ channels, K+ remain closed, action potential reached after threshold is reached4. Falling: Most of the Na+ channels now inactivated, block flow of Na+, K+ channels open, K+ flows outside of cell, inside becomes more negative5. Undershoot: Na+ channels close, K+ remain open. Then K+ close, Na+ open, membrane returns to resting state. K+ channels extended time open contributes to the "undershoot", making cell more negative decreases likelihood an action potential can be reached again until appropriate norms are reestablished and also decrease likelihood of an action potential moving "backwards" in an axon.

Front 38

Describe function of location current of ions across a plasma membrane

Back 38

The currents of ions cause the action potential to be propagated along the length of the action (movement of a nerve impulse)

Front 39

Chemically gated channel (short distance)

Back 39

Channels open when chemical binds, exactly like a receptor. Transmission of info occurs at synaptic terminal. Usually involves release of neurotransmitter and then binds/activates specific receptors in membrane

Front 40

Ligand-gated ion channel

Back 40

Receptor protein binds and responds to neurotransmitter. Results is a postsynaptic potential, binding of neurotransmitter to particular part of receptor opens channel, allows specific ions to diffuse across the membrane. Aka ionotropic receptor

Front 41

Metabotropic receptor

Back 41

Neurotransmitter binds to metabotropic receptor. Movement of ions through channels depends on one or more metabolic steps. Activates signal transduction pathway in postsynaptic cell involving a second messenger. Effects of this system slower but longer lasting.Example: Norepinephrine - Binds to metabotropic receptor, neurotransmitter receptor complex activates g-protein, turns on adenylyl cyclase (converts ATP to cAMP), cAMP activates protein kinase A, phosphorylates specific ion channel proteins in postsynaptic membrane causing them to open or close.

Front 42

When is a signal terminated?

Back 42

Receptor activation or postsynaptic responses cease when neurotransmitter is cleared from synaptic cleft. Neurotransmitters may be removed by diffusion, inactivation by an enzyme, or recapture into presynaptic neuron and recycled.