PHYS

How many molecules of ACh are necessary to completely activate the ACh receptor?

2

The reticular formation is a network of neurons found along the brain stem. Many of the functions of the reticular formation are widespread as a result. Which of the following would occur if you were to disrupt the functions of the reticular formation?

A person would have a difficult time waking due to an inability to arouse the brain.

Most neurons have at least two processes extending from the soma, or cell body. Which type of neuron only has one process extending from the cell body?

A pseudounipolar neuron

What is a varicosity in the autonomic nervous system?

A series of swollen ends that act as synapses.

Neurons in the parasympathetic pathway use which of the following neurotransmitters?

Acetylcholine

What is the trigger for ACh into the synaptic cleft of a neuromuscular junction?

Acetylcholinesterase opens vesicles allowing ACh to diffuse into the cleft.

Which of the following is a modified sympathetic ganglion?

Adrenal medulla

Information coming into the central nervous system is transmitted along _______ neurons.

Afferent and sensory

Which of the following choices best describes the path of sensory information from the receptor into the spinal cord?

Afferent neuron to dorsal root ganglion to dorsal horn

Which of the following is the type of adrenergic receptor found in most sympathetic target tissues?

Alpha 1

What happens if a graded stimulus is of sufficient strength to reach threshold at the trigger zone?

An action potential occurs.

What best describes the resting membrane potential?

An electrical gradient that exists between the intracellular and extracellular fluids.

Cerebrospinal fluid circulates through the central nervous system. It leaves the CNS and enters the bloodstream via which structure?

Arachnoid villus

The division of the efferent nervous system that controls smooth and cardiac muscles and many glands is the _______ division.

Autonomic

Which nervous system division has parasympathetic and sympathetic branches?

Autonomic division of the efferent nervous system.

The sympathetic and parasympathetic nervous systems are divisions of which system?

Autonomic nervous system

Which of the following best describes the direction and function of efferent signals?

Away from the central nervous system, cause motor effects in gland or muscles.

What specific tissue makes up the corpus callosum?

Axons

The part of the brain anatomically most similar to the spinal cord is the?

Brain Stem

Most of the cranial nerves originate in the?

Brain stem

Which of the following are components of the central nervous sytsem?

Brain, spinal cord

Which of the following is/are targets of the efferent nervous system?

Cardiac muscle, glands, smooth muscle, skeletal muscle.

The brain region that is identifiable by its folds and grooves is the?

Cerebellum and Cerebrum

The ________ is a salty fluid continuously secreted into hollow cavities known as ________. This fluid is secreted into these cavities by the _______, a specialized tissue consisting of capillaries and transport epithelium.

Cerebrospinal fluid, ventricles, choroid plexus

Muscarine, a chemical produced by certain mushrooms, binds to muscarinic receptors mimicking the effect of acetylcholine. How do you think administering this chemical would change body function? The drug would ______

Change the functionality of the heart, the functionality of the smooth muscle within the digestive system and change the functionality of certain exocrine and endocrine glands.

Cerbrospinal fluid is produced by the?

Choroid plexus

What is responsible for selectively transporting substances into the ventricles from the bloodstream?

Choroid plexus

Which structure allows communication between the two hemispheres of the brain?

Corpus callosum

The part of the neuron that receives most of the incoming signals is the?

Dendrite

The gray matter of the central nervous system contains mainly ________ and is located ___________ of the spinal cord.

Dendrites, axon terminals, and cell bodies of neurons; in the central portion.

What would happen to the membrane potential if a cell suddenly becomes more permeable to Na+?

Depolarize

Sometimes the effects of sympathetic stimulation can be contradictory in the same types of tissue. What mechanism explains these opposite effects?

Different receptors for the same neurotransmitter.

Cell bodies of sensory neurons are located in?

Dorsal root ganglia

What is the collection of neurons in the walls of the digestive system called?

Enteric nervous system

Neurotransmitters are usually released into synapses by?

Exocytosis

Which brain lobe contains the main areas controlling skeletal muscle movement?

Frontal

The brain consumes about half of the _______ circulating in the body.

Glucose

Most neurons contain a large number of mitochondria. Which characteristic of neurons does this reflect?

High level of aerobic metabolism

Where do most action potentials originate?

Initial segment

During an action potential, activation of voltage-gated sodium and potassium channels occurs at different rates. What is the difference on ion flow across an axon membrane?

Initially, Na+ flows into the cell followed by K+ flowing out of the cell.

Nerve cells in the central nervous system are primarily?

Interneurons

The neurons of the central nervous system are also known as?

Interneurons

Why is the parasympathetic nervous system also called the cranio-sacral division?

Its nerves arise in the head and sacrum.

What is an appropriate classification for the ACh receptor found in the neuromuscular junction?

Ligand-gated, nonspecific, cation channel

The part of the brain known as the center of emotion is the?

Limbic system

Which area of the brain controls basic functions as breathing, swallowing, and vomiting?

Medulla oblongata

What would the effect of ACh binding to its receptor on the postsynaptic muscle cell?

Na+ would flow into the cell and K+ would flow out of the cell.

A molecule that carries information across a synaptic cleft is a?

Neurotransmitter

Which type of receptors are found in the neuromuscular junction?

Nicotinic

The two main types of acetylcholine receptor are known as?

Nicotinic and Muscarinic

Which neural term is synonymous with rough endoplasmic reticulum?

Nissl substance

The somatic nervous system and the parasympathetic nervous sytem both release acetylcholine onto their target tissues. Do you predict that this would indicate that these two pathways carry out the same effects? Why or why not?

No, because the receptors found on the target tissue for each pathway are different.

Which glial cell produces myelin in the central nervous system?

Oligodendrocytes

What characterizes repolarization, the second phase of the action potential?

Once the membrane depolarizes to a peak value of +30mV, it repolarizes to it's negative resting value of -70mV.

What initiates exocytosis of synaptic vesicle contents in an axon terminal?

Opening of voltage-gated Ca2 channels.

Which of these characteristics is the same in both the sympathetic and parasympathetic branches for the vast majority of neurons?

Preganglionic neurotransmitter

Which of the following neurons or groups of neurons are NOT considered to be a part of the efferent pathway?

Sensory

The target tissue of somatic motor neurons is?

Skeletal muscle

Somatic motor neurons control?

Skeletal muscles

A single neuron is stimulated at the central nervous system; this signal travels all the way to the target tissue, where the neurotransmitter acetylcholine is released onto the target tissue. The acetylcholine binds to a nicotinic receptor to induce skeletal muscle contraction. These steps describe the function of which branch of the efferent nervous system?

Somatic

The cells that we are capable of controlling consciously are the

Somatic Motor Neurons

These neurons secrete the neurotransmitter acetylcholine onto their targets?

Somatic motor and parasympathetic motor.

Which of the following are components of the efferent nervous system?

Somatic motor neurons, parasympathetic neurons & sympathetic neurons.

Through which layer of the meninges does cerebrospinal fluid run?

Subarachnoid space

The motor neurons primarily associated with the fight-or-flight responses are the _____ neurons.

Sympathetic

The diameter of blood vessels varies under the control of _______ neurons, which cause the diameter to _______.

Sympathetic; either increase or decrease, depending upon the type of receptor present.

The small space between the sending neuron and the receiving neuron is the?

Synaptic cleft

Composed of many small nuclei, an area that integrates as well as relays sensory information that passes through it.

Thalamus

What best describes the concept of permeability?

The ability of a molecule to cross the cell membrane.

What makes the brain more complex than a simple, reflex pathway?

The ability to generate information in the absence of external input.

From what does the blood-brain barrier result? Which of the following best describes the role of the blood-brain barrier?

The blood-brain barrier is formed by tight junctions between capillary endothelial cells thus preventing the movement of solutes between cells.

Which part of the nervous system is the most different when comparing humans to other animals?

The cerebrum.

Brain ventricles develop from

The lumen of the neural tube.

Why is an action potential conducted in only one direction, from an axon hillock to an axon terminal?

The membrane channels upstream are refractory and cannot open.

What characterizes depolarization, the first phase of the action potential?

The membrane potential changes from a negative value to a positive value

What event triggers the generation of an action potential?

The membrane potential must depolarize from the resting voltage of -70mV to a threshold of -55mV.

Which of the following is an example of antagonistic control?

The parasympathetic stimulation causes bronchoconstriction while sympathetic stimulation causes bronchodilation.

In a graded potential, what is the effect of cytoplasmic resistance and current leak?

The strength of the signal inside the cell decreases over distance.

The effects of the sympathetic nervous system are divergent, meaning that a single stimulus can have an effect on a large number of targets. In other words, when the SNS is activated, all of the organs it innervates are stimulated. This does not occur in the parasympathetic system. Why?

The sympathetic ganglia spreads the stimulus to all postganglionic sympathetic neurons.

Whether or not a neuron produces an action potential at a given moment depends on?

The total potential change reaching threshold voltage at the trigger zone.

When calcium ions enter the synaptic terminal,

They cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.

Motor fibers leave the spinal cord's gray matter via this?

Ventral root

What opens first in response to a threshold stimulus?

Voltage-gated Na+ channels

What is the first change to occur in response to a threshold stimulus?

Voltage-gated Na+ channels change shape, and their activation gates open

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron,

ion channels in the plasma membrane of the receiving neuron open.

In most cells, the concentration of ions contributing to the membrane potential are ______ in the intracellular fluid compared to the extracellelular fluid, with the exception of _______ ions.

lower; potassium

If a signal from a sending neuron makes the receiving neuron more negative inside,

the receiving neuron is less likely to generate an action potential.