Daily Quizzes for Exam IV A&P I

These questions are to help you quiz yourself. To see my answers, select the area underneath the question using your mouse. (click and drag)  Don't print this out, or the answers will be visible as well!

What are the three basic functions of the nervous system?
Sensing, integrating (analyzing) and motor (responding)
What parts of the nervous system make up the central nervous system? 
Brain and spinal cord
The peripheral nervous system?
Cranial nerves and peripheral nerves
What does afferent and efferent mean in the nervous system? 
Afferent nerves are sensory nerves that bring information into the CNS.
Efferent nerves are motor nerves that stimulate effector organs (muscles and glands). They originate in the CNS.

What is the somatic nervous system?
The nerves that bring sensory information in (like sight and sound) and those that control skeletal (voluntary) muscle.

 What is the autonomic nervous system?
This is the part of the peripheral nervous system that controls involuntary functions within the body, cardiac and smooth muscle, and glands.
What are the two divisions of the autonomic nervous system? 
The sympathetic nervous system - "fight or flight" (think bear)
The parasympathetic nervous system - "feed and breed" (think book)

What are the three basic parts of a neuron?
The cell body or perikaryon, the dendrites, and the axon.
 In what direction does current flow through them? 
Current (information) comes in to the cell body and/or dendrites, and flows down the axon.
 What do you find in synaptic end bulbs?
Neurotransmitters - chemicals that can excite or inhibit neurons and effector organs.
What are Nissl bodies (chromatophilic substance) and what do they do? 
These are rough endoplasmic reticulum- rough because they have ribosomes, which are the workbenches for putting proteins together.

What is a nerve fiber? 
Any process of a neuron, but usually we are referring to the axon.
What exactly is a nerve?
Several nerve fibers that travel the same path and are wrapped in connective tissue. They are part of the peripheral nervous system, and usually carry both sensory and motor fibers.

 What is a ganglion?
A group of cell bodies of neurons found in the peripheral nervous system.
 What is a tract?
Within the central nervous system, it is a group of the same type of neurons (sensory or motor) that travel together and are not separated by connective tissue.
What are the two types of axonal transport, and what do they do? 
Slow axonal transport (axonal flow) - one way delivery of axoplasm to the axon.
Fast axonal transport - delivers proteins and other substances and organelles to the axon, and returns substances for recycling.
Which can be dangerous?
Fast axonal transport, because it can bring viruses and toxins back up to the body of the neuron.
**Neuroglia: 
Which four glial cells are part of the CNS?
Astrocytes, oligodendrocytes, microglia and ependymal cells.
Which cells act as phagocytes?
Microglia
Which cells form the blood-brain barrier?
Astrocytes
Which cells provide the myelin sheaths for the neurons of the CNS?
Oligodendrocytes
Which cells make and circulate cerebrospinal fluid?
Ependymal cells
What cell provides the myelin sheath for axons in the PNS?
Schwann cells - neurilemmocytes

What two things does myelination do for a cell in the PNS? 
It speeds up impulses and aids in the regrowth of the axon after damage.
Why don't axons regenerate in the central nervous system?
Astrocytes form a scar tissue that prevents it.
What is multiple sclerosis?
It occurs when the myelin in the CNS breaks down and plaques form. The nerve cells short circuit, resulting in muscle weakness, visual disturbances, etc. It may go into periods of remission with partial recovery of function, but is generally progressive.
What is found in gray matter?
Cell bodies, dendrites, and unmyelinated axons.
Where is gray matter found?
In the center of the spinal cord (H pattern), on the surface of the cerebral hemispheres, and in areas called nuclei within the cerebral hemispheres (and some other parts of the brain as well).
Why is white matter white?
Because of the myelin around the axons, which is high in lipids (fat) (Think whole milk vs. skim milk!)
What is a resting membrane potential?
A separation of charges on either side of the membrane, the outside of the cell being positive and just inside the membrane is negatively charged. This is the same way we make a battery.
What ions are more concentrated inside the cell?
There is more potassium (K+) inside the cell than outside. The negatively charged ions (anions) are phosphates and the negatively charged amino acids of proteins.
Outside the cell
Sodium (Na+) and chloride ion (Cl-)
What is a leakage channel?
This type of channel is always open and is often very specific, allowing only one substance or ion to pass through.
A gated channel?
This channel can open and close, like a gate, with the proper stimulus.
What are the kinds of gated channels?
Voltage gated, chemically gated, mechanically gated and light gated.
What makes current in a cell?
The flow of charged particles - usually sodium ions.
Know the difference between graded potentials and action potentials:
                                        graded potentials                     action potentials
Amplitude:                variable = strength of stimulus                  all-or-none

Duration:                   longer- several msec. to                        1/2- 2 mseconds
                                            several minutes

Channels:       chemically, mechanically or light gated              voltage gated

Location:      mainly on dendrites and cell body                     on trigger zone of axon and along axon

Refractory      No (may sum if at the same time or close)                   Yes
      Period:

What is a threshold?
The amount of stimulus needed to cause an action potential in a nerve or muscle cell.
What is depolarization?
It occurs when the inside of the cell becomes less negative relative to the outside of the cell - brings the axon toward threshold and beyond during an action potential.
Hyperpolarization?
This makes the inside of the cell more negative relative to the outside of the cell - brings the axon further away from reaching threshold, and now we need a larger stimulus to get the neuron to fire.
Review:
In a resting neuron, the outside of the membrane is positively charged and just inside the membrane is negatively charged.  The cell body can have chemically, mechanically, or light gated channels which open and allow sodium ions  to enter into the neuron. These are called graded potentials because the response is proportional to the strength of the stimulus. When the trigger zone of the axon reaches threshold , an action potential is produced, and this is an all-or-none response. The opening of voltage gated channels in the axolemma causes an electrical impulse  to travel down the axon. The axon reestablishes the resting potential by closing the sodium ion channels and opening potassium ion channels. During an absolute refractory period no stimulus will cause the neuron to fire again. During a relative refractory period a strong stimulus (more than the normal threshold) will cause the neuron to fire again.
 

How does saltatory conduction differ from continuous conduction?
Saltatory conduction is faster and requires less energy to reestablish the resting potential.
What two factors affect the speed of impulse propagation ?
Whether or not the nerve is myelinated, and the diameter of  the neuron.
When the action potential reaches the synaptic end bulb, in addition to the Na+ and K+ channels, what other ion comes into the cell through voltage-gated channels and causes the release of the neurotransmitter?
Calcium ions
How does the neurotransmitter get across the synaptic cleft?
simple diffusion
What is an excitatory postsynaptic potential?
This occurs when a postsynaptic neuron is depolarized or brought closer to threshold.
What is an inhibitory postsynaptic potential?
This occurs when a postsynaptic neuron is hyperpolarized or taken farther away from threshold.

What is summation?
The adding together or two or more stimuli to bring a neuron closer to or further away from threshold.
What are two types of summation?
Temporal (over time) summation - one neuron releases neurotransmitter several times to affect a postsynaptic neuron. 
Spatial summation (in space) - several neurons all converge on a postsynaptic neuron and each release neurotransmitter to affect the postsynaptic neuron.
Where is acetylcholine used as a neurotransmitter?
It is used in several places in the body, notably at the neuromuscular junction, from the preganglionic neurons of the sympathetic and parasympathetic nervous systems and from the postganglionic neurons of the parasympathetic nervous system.
Can a certain neurotransmitter be both excitatory and inhibitory?
Yes, look at the effects of the neurotransmitters of the parasympathetic and sympathetic nervous systems. Their neurotransmitters will stimulate some muscles and glands while inhibiting others.
What other substances act as neurotransmitters? 
Amino acids, biogenic amines (modified amino acids), neuropeptides (short chains of amino acids) and some gases.
 Which ones are the bodies natural pain killers?
Enkephalins and endorphins.
Which one is made only when it is needed, and why is it made this way?
The gas nitric oxide, because it is lipid soluble and can diffuse through the axolemma.
 

CHAPTER 11 :
Where is cerebrospinal fluid formed? 
CSF is a filtrate of blood. Blood is filtered through the capillaries in the choroid plexes of the ventricles and is modified and circulated by the ependymal cells.
 Where does the CSF flow, and where does it return to the vascular system?
CSF flows through the subarachnoid space and returns to the blood in the dural sinuses through the arachnoid villi or arachnoid granualtions.
What is the filum terminale and the denticulate ligaments?
These are both extensions of the pia mater which anchor and support the spinal cord within the vertebral column. The denticulate ligaments are found between the ventral and dorsal roots of the spinal nerves, and the filum terminale extends from the conus medularis to the coccyx.
Where are spinal taps done?
Between L3 and L4 or between L4 and L5 so that the needle would pass between the spinal nerves of the cauda equina.
Which type of nerves  enter or leave the spinal cord by the posterior or dorsal root? 
Sensory. The cell bodies of these neurons are located in the dorsal root ganglion.
By the anterior or ventral root?
Motor neurons. Their cell bodies are located in the anterior gray horn.
What cell bodies are found in the  lateral gray horn?
These are the cell bodies of the neurons of the autonomic nervous system. 
Where is the central canal? What flows through it?
In the center of the spinal cord. Cerebrospinal fluid.
What is a reflex? 
It is a fast, predictable, automatic, and subconscious response to a change inside or outside the body.
What is the difference between a somatic and an autonomic reflex?
Somatic reflexes involve skeletal muscle, and are usually easier to test. Autonomic reflexes involve responses from smooth muscle, cardiac muscle,  and glands. Except for the pupillary light reflex, these are more difficult to demonstrate.
What neural tube defects can be prevented if a pregnant woman gets enough of what vitamin?
A pregnant woman should take folic acid ( a B vitamin) to prevent spina bifida and anencephaly.
The cerebrum:
What does the corpus callosum do?
It is the only major bridge between the two cerebral hemispheres, and allows communication between the two hemispheres.
What is an association area, and what does it do?
An association area processes the information that comes into specific areas in the cerebrum. These areas help you to interpret what you are seeing, feeling, hearing ,etc.
What is memory consolidation?
A way to move information from short term memory into long term memory by repeated retrieval of that information (take it out, look at it, put it away. Repeat.)
What happens when the basal ganglia degenerate?
Not enough of the inhibitory neurotransmitter dopamine is formed, and this leads to the tremors of Parkinson's disease.
What happens if too much cerebrospinal fluid is formed, or not enough drains?
In an infant, before the fontanels close, the head will swell. The condition of over production of CSF  is hydocephalus. In older children and adults this puts pressure on the brain, causing headache, vomiting, optic atrophy,  and mental disturbances. In some adults overproduction produces benign intercranial hypertension which can be treated by withdrawing CSF with a lumbar puncture.
The diencephalon:
What makes up the diencephalon? 
The thalamus, hypothalamus, mamillary bodies and pineal gland.
What does the pineal gland do?
The pineal gland receives information from the eyes and responds to light, and is therefore sometimes called the "third eye." It secretes a hormone called melatonin, which regulates the body's biological clock and promotes sleepiness (sometimes used to help get over "jet lag.") It may also affect the onset of puberty.
What does the infundibulum make?
It makes hormones or factors that control the release of hormones from the anterior pituitary gland.
The mamillary bodies are associated with what sense?
The sense of smell.
What does the thalamus do?
It is the main relay station for sensory information to the cerebral cortex, and also plays a role in emotions, memory, awareness and learning.
What does the hypothalamus control?
The autonomic nervous system, the pituitary gland, regulation of eating and drinking, body temperature, diurnal(daily) rhythms and states of consciousness, and emotional and behavioral patterns.
What part of the brain is called the "emotional brain"? Why?
The limbic system, because it controls the emotional aspects of behavior and memory (memory is easier when associated with an emotional response.) It produces behaviors associated with rage, pain, pleasure, fear, anger, affection and sexual feelings.
Where are the superior and inferior colliculi (corpora quadrigemina)?
On the posterior surface of the midbrain, as part of the area called the tectum.
What do they do?
The 2 superior colliculi contain reflex centers for coordination of  movements of the eyes, head and neck in response to visual stimuli .
The inferior colliculi have reflex centers for movements of the head and trunk in response to sounds.
What does the red nucleus do?
It coordinates muscle movements and provides reflexes that maintain posture.
 What does the pons do? What bodily function does it help control?
It serves as a "bridge" between the spinal cord and the brain, and links parts of the brain together. It has centers that aid in controlling breathing. It also gives rise to several cranial nerves.
What happens in the pyramids ?
Mummies are buried here. No, actually the large motor tracts cross over from one side to the other at the decussation of pyramids. (Remember the right side of your brain controls the muscles on the left? ) 
 What regulatory centers do we find in the medulla oblongata ?
Centers that regulate heart rate and force of contraction, muscles in the walls of blood vessels, breathing and modified respiratory movements, like sneezing, coughing and vomiting.
What is the reticular activating system, and what does it do?
It is part of a netlike formation of gray and white matter that runs through the brain stem. The RAS is responsible for maintaining consciousness and awakening from sleep. It gets signals from the eyes, ears, and the sense of touch. (but not the sense of smell, so don't believe the Folger's commercial that claims the smell of their coffee wakes you up!)
What is the arbor vitae? The vermis? 
The arbor vitae or "tree of life" is the white matter inside the hemispheres of the cerebellum. The vermis is a wormlike structure found on the posterior surface of the cerebellum between the two hemispheres.
What is the main function of the cerebellum?
Comparing what the cerebrum intends for the muscles of the body to do with what the body is actually doing, and making corrections to produce smooth, coordinated movements.
What are "intention tremors"?
Shaking movements produced by people with cerebellar damage. The shaking increases the closer they get to grasping their intended target.
How many pairs of spinal nerves are there? How many are cranial? Thoracic? Lumbar? Sacral? Coccygeal?
31. 8/12/5/5/1
What is a dermatome?
The area of skin that sends its sensory information to the brain through a particular spinal nerve. Muscles are innervated in the same way - a specific spinal nerve carries motor information to a myotome.
How would the fact that each division of the autonomic nervous system has several this be helpful to someone with asthma?
We can formulate drugs that affect only part of the system. In other words, we can give someone with asthma a sympathomimetic drug that opens their airways without raising blood pressure and heart rate also.

Which neurotransmitter would have a longer lasting effect, acetylcholine or norepinephrine? Why?
Norepinephrine. When the sympathetic nervous system is stimulated norepinephrine and epinephrine are released from the adrenal medulla and circulate through the blood stream, acting as hormones. The effects will last until they are removed from the blood stream, usually taking 20 mins. or so.