bio psych exam 1

What are the different parts of the neuron?

- Dendrites - Soma/cell body - Axon - synapse

Identify the functions of the major structures of the cell.

- Membrane - Nucleus - Mitochondria - Ribosomes - Endoplasmic reticulum

How are action potentials propagated? Why do they only go one way down the axon?

- Na+ from AP flows into membrane areas, patch of membrane depolarizes, forms AP, next patch of membrane depolarizes, Na+ channels open, so forth. - Previous patch can't reform AP bc it is refractory due to closing + inactivation of Na+ channels during hyperpolarization (only moves toward the synapse because of this)

What is temporal summation

- Sherrington observed - repeated stimuli can have a cumulative effect + produce a nerve impulse when single stimuli is too weak

What is spatial summation?

- Synaptic input from several locations can have cumulative effect + trigger a nerve impulse - Each neuron recieves axons producing synch. responses

What steps are required for synaptic transmission of an action potential?

- Travles down axon terminal + depolarization opens voltage gated Ca2+ channels - Opening allows Ca2+ to flow into cell down concentration gradient - Ca2+ influx and NTM into the synaptic cleft (with diffusion)

What are voltage gated channels and what is their role in neuronal signaling?

- Typically closed at rest, but can open by changes in voltage/charge inside the cell. - Allows ions to move down concentration gradient, no energy required - Specific for specific ions

Function of Microglia?

- immune-like cells in the CNS that remove damaged neurons - eat invading microorganisms + dead/damaged neurons

Function of Oligodendrocytes and Schwann cells?

- insulate neuronal axons and improve electrical transmission along them - makeup myelin - o: central - s: peripheral

Name some features of neurons.

- long branching extensions - different parts - motor and sensory

Function of Ependymal cells?

- produce cerebrospinal fluid

What are some features of NTM receptors?

- proteins found in membrane of dendrites in post-synaptic neuron - bind to specific NTMs - after binding cause changes

What kinds of chemicals can cross the blood brain barrier?

- small, uncharged molecules such as oxygen, carbon dioxide, and water cross the blood-brain barrier passively. - chemicals that dissolve in the fats of the membrane.

Function of Astrocytes?

- star-shaped cells that provide structural and nutritive support to neurons - "feet" wrap around capillaries and make another barrier - synch activity of axon wrapping around presynaptic terminal + take up chemicals from axon

What are examples of purine NTMs?

ATP, adenosine, maybe others

Types of Neurotransmitters

Amino acids, monoamines, peptides/neuropeptides, purines, gases

Neurons typically have one ____, but many _____

Axon; dendrites

What is the 1st phase of action potential and what molecular changes cause them to arise?

Depolarization - inside of the cell rapidly becomes less neg/more pos

Professor Russom is giving a talk about neurotransmitters. She tells the class that most neurotransmitters are synthesized from _____.

Hormones

What is the 3rd phase of action potential and what molecular changes cause them to arise?

Hyperpolarization - overshoot of resting membrane potential, cel becomes even more neg than at rest, then creeps up to resting membrane potential during later phase

Which event will increase the concentration gradient of sodium?

Increasing activity of the sodium potassium pump

Glutamate opens sodium gates, enabling sodium ions to enter the postsynaptic cell. What type of effect is this?

Ionotropic

The "spontaneous firing rate" of a neuron refers to ____.

Its rate of producing action potentials even when it is not stimulated

What is saltatory conduction? From what does it arise?

Myelin sheath surrounds axon except nodes of ranvier. AP jumps from node to node because myelin insulates axon, allowing less ion flow out across membrane. Jumping speeds rate of AP propagation down axon.

What are examples of gas NTMs?

NO (nitric oxide), maybe others

What are peptides/neuropeptides?

NTM made of long chains of amino acids linked together to form protein (ex. endorphins)

What are amino acids?

NTM packaged in vesicles (ex. glutamate, GABA, glycine)

What are monoamines?

NTM synthesized by .chemical modification of amino acids (ex. dopamine, serotonin, norepinephrine)

What is the 2nd phase of action potential and what molecular changes cause them to arise?

Repolarization - inside of cell rapidly becomes less pos/more neg, and returns toward neg resting membrane potential

How is synaptic signaling terminated?

Reuptake, Uptake, Degradation, Diffusion

Dr. Andrus studies reflexes and has demonstrated that a certain reflex does not occur if there is a single stimulus. He found that there needs to be ______ (several, rapidly produced stimuli) for the reflex to occur.

Temporal summation

What is the "spontaneous firing rate"?

The periodic of action potentials despite synaptic input - EPSPs increase AP above - IPSPs decrease AP below

The sodium potassium pump pumps ____ into the cell and ___ ions out of the cell with every cycle

Three K; two Na

In order to produce an action potential, the collective amount of depolarization must exceed the

Threshold of excitation

What is NOT required for neurotransmitter release?

Voltage gated sodium channels

What are anatognists?

a drug that blocks opioids by attaching to the opioid receptors without activating them (ex. naltrexone and naloxone)rec

What is the neuronal cell membrane made of?

a phospholipid bilayer (phospholipid molecules, protein molecules)

What are brain tumors made of?

abnormally over-proliferating cells

How does the blood-brain barrier work?

active transport systems pump glucose + amino acids across membrane

What is "coincidence detection"?

after summation, neurons integrate info + decide if it's important rather than passing on

What are some features of ligands?

allow ions to cross across cell membrane in response to binding. (the key into the receptor hole)

How are Neuropeptides made?

amino acids chaining together

Which of the following glial cells is most involved in the blood brain barrier:

astrocytes

What are four types of glial cells?

astrocytes, oligodendrocytes and schwann cells, microglia, ependymal cells

What are metabotropic receptors?

binding of NTM doesn't open ion channel in receptor, but indirectly opens ion channel by activating other intracellular proteins

What are ionotropic receptors?

binding of NTM opens ion channel in receptor and allows ions to flow into cell

What is degradation?

breakdown of NTMs by enzymes in the synapse (neuropeptides)

What are graded potentials?

brought about by external stimuli (in sensory neurons) or by neurotransmitters released in synapses (in the post synaptic cell)

What is Ca+'s role in the synapse?

causes fusion of NTM vesicles with the membrane + dumping of NTM into the synaptic cleft, which moves across the cleft by diffusion.

What are neurotransmitters?

chemicals that are produced by presynaptic neurons and are released in response to an action potential and have effects on postsynaptic neurons

Function of Nucleus?

contains the chromosomes

What is an EPSP?

depolarization of postsynaptic membrane in which its resting membrane potential becomes less neg and more likely to fire an AP (goes down) - basis of temporal and spatial summation

The concentration gradient refers to the ____.

difference in distribution for various ions between the inside and outside of the membrane

What are agonists?

drug that activates certain receptors in the brain (ex. heroin, oxycodone, methadone, hydrocodone, morphine, opium and others)

How are neurotransmitters released?

from a Ca2+ influx fusing to NTM vesicles

What is an IPSP?

hyperpolarization of postsynaptic membrane in which its resting membrane potential becomes more neg and less likely to fire an AP (goes up)

Function of Cell body or soma?

integrates and processes signals and decides whether to create a signal of its own ; also carries out cellular functions such as energy production and protein synthesis

When a neuron's membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell.

into; into

How do ions respond to concentration gradients?

ions flow down their concentration gradient

How do ions respond to electrical (voltage) gradients?

ions flow down their voltage gradient

where are neuropeptides stored?

large dense-core vesicles

How do IPSPs and EPSPs influence post-synaptic cell?

likeliness of firing an action potential

What is cortex?

made up of neurons (brain)

Function of Endoplasmic reticulum?

network of thin tubes that transports newly synthesized proteins to their location

What is the resting voltage of a neuron, and how is this achieved?

outside more positive than inside, membrane is polarized (-70mV)

What is diffusion?

passive movement of NTM away from synapse (neuropeptides)

Function of Mitochondrion?

performs metabolic activities and provides energy that the cells requires

What is hyperpolarization?

positive ions flow out of the cell and becomes more negative inside compared to outside

What is the neuronal cell membrane made of, and what is its importance?

protein channels that permit certain ions to cross at a controlled rate

What are channels and pumps made of? What are some of their features?

protein complex that continually pumps ions out of the cells while drawing 2 ions into the cell. It maintains the electrical gradient and uses active transport with ATP

What is active transport across the blood brain barrier?

pump glucose and amino acids across the membrane

Function of dendrites?

receive signals from other neurons

Function of Synapse?

region where the axon terminal of one neuron comes close to the dendrite of another neuron

How is membrane polarization maintained?

selective permeability controls the flow of charged ions

Function of membrane?

separates the inside of the cell from the outside environment

Function of Ribosomes?

sites at which the cell synthesizes new protein molecules

Where are neurotransmitters stored?

small secretory vesicles (SSVs) in the axon terminals of presynaptic neurons

What's the blood brain barrier?

surrounds brain + blocks most chemicals from entering

What did Ramon y Cajal contribute to modern neuroscience?

the first to demonstrate that the individual cells comprising the nervous system remained separate. - they did not merge into each other

What is the effect of receptor binding on membrane voltage?

the inside of the cell is either less negative or more negative inside after the post-synaptic potential. (IPSP/EPSP)

What is uptake?

transport of NTM into, and deactivation by glial cells (amino acids and monoamines)

What is reuptake?

transporter proteins move NTM back into presynaptic neuron axon terminal (amino acids and monoamines)

What is passive transport across the blood brain barrier?

unwanted molecules back go back to the circulatory system. Small polar molecules, such as glucose, amino acids, organic anions and cations, and nucleosides

What does the brain use as a fuel source? How is this fuel supplied?

vertebrate neurons depend on glucose (with thiamine/vitamin b1 and oxygen)

What are ions?

when an atom gains or loses an electron, it becomes either positively or negatively charged

What is the distribution of ions inside and outside the cell membrane at rest? How does this relate to chemical and electrical gradients?

when channels open, it permits some type of ion to cross. When closed it prevents the passage. Electrical pulls more into the cell but they leak out with positive charge.

What is depolarization?

when positive ions flow into the cell and becomes less negative inside compared to outside