Exam #4 extras Flashcards
which pathways allow different parts of the nervous system to affect the activity of a neuron and when several neurons synapse with a smaller number of neurons?
convergent pathway
which pathway allows one part of the nervous system to affect more than one part of the nervous system and a small number of neurons synapse with a larger number of neurons?
divergent pathway
what is a reverberating circuit?
important functions that are periodically active such as sleep/wake cycle and respiration
where is sodium concentration higher?
extracellular
what is a nucleus
a cluster of cell bodies and their dendrites in the CNS
what is a ganglion?
a cluster of cell bodies and their dendrites in the PNS
what are some similarities between EPSPs and IPSPs? (3) (BCS)
1) both are graded potentials
2) conducted in a decremental fashion
3) size is proportional to the strength of the stimulus
what ionic changes in the membrane will promote depolarization?
sodium and calcium
are graded potentials reversable?
yes
what is temporal summation?
a single synapse fires rapidly in sequence
what is a IPSP?
when the hyperpolarization of a postsynaptic neuron occurs to a neurotransmitter
why does hyperpolarization of a postsynaptic neuron occur with a IPSP?
because it is more likely to reach a threshold
what are IPSPs due to?
the opening of chloride and potassium channels (hyperpolarization)
what is the purpose of the absolute refractory period?
to prevent potentials from being generated in the reverse direction
what is a plexus?
an extensive network of nerves outside the CNS
during an action potential what is repolarization due to?
potassium ions leaving the cell
which nerve fibers form the autonomic system?
B and C
the propagation of action potentials from one node of ranvier to another along a myelenated axon
saltatory conduction
what type of neurons are motor neurons and interneurons structurally?
multipolar
what does gray matter primarily contain?
neuron cell bodies
compared with the inside of the resting plasma membrane what is the outside surface of the membrane?
positively charged
what are leak channels responsible for?
the ion permeability of the resting plasma membrane
if the permeability of the plasma membrane to potassium increases what happens to the resting membrane potential difference and what is that called?
it increases and it’s called hyperpolarization
what happens to the plasma membrane during repolarization?
potassium diffuses out of the cell
what is occurring during the absolute refractory period? (2) (LP)
1) limiting of how many action potentials can be produced during a given time
2) prevention of an action potential from starting another action potential at the same time at the same point on the plasma membrane
where are neurotransmitter substances stored in vessicles located?
in specialized portions of the axon
in convergent pathways what does the response of the postsynaptic neuron depend on?
the summation of EPSPs and IPSPs
what is the function of reciprocal innervation?
promotes relaxation of extensor muscles while opposing flexor muscles contract
what do gamma motor neuron do?
they stimulate contraction of muscle spindles
what do alpha motor neurons do?
stimulate muscle contraction
what is a muscle spindle?
the sensory receptor of a stretch reflex
which of the ramis for plexuses?
the ventral ramis
what is the function of a crossed extensor reflex?
promotes relaxation of extensor muscles while opposing flexor muscles contract
how many of each nerve are there?
8 cervical, 12 in the thoracic, 5 in the lumbar, 5 in the sacral and 1 in the coccygeal.
whata kind of fibers (axons) does dorsal roots ONLY consist of?
sensory
where do axons of sensory neurons synapse with cell bodies of interneurons?
in the posterior horn of spinal cord gray matter
what is the possible reason for a reflex response accompanied by conscious sensation of pain?
divergent pathways
what is responsible for regulating the sensitivity of the muscle spindle?
gamma motor neurons
what is a collection of spinal nerves that join together after leaving the spinal cord called?
a plexus
what are some characteristics of a dermatome? (3) (AEC)
1) area of skin supplied by a pair of spinal nerves
2) exists for each spinal nerve except C1
3) can be used to locate the site of spinal cord or nerve root damage
what 2 nerves combined with the same sheath make up the sciatic nerve?
common fibular (peroneal) and tibial
what would effect the damage to some afferent neurons of the PNS?
it would interfere with a person’s ability to sense a variety of stimuli.
what are the basic functions of the cerebrum? (3)
1) controls conscious motor activity
2) controls thought
3) controls conscious perception
what is the function of the brainstem?
it’s a critical center for essential survival reflexes and strong areas of destruction can be fatal
what are the functions of the midbrain?
1) involved in maintaining muscle tone and coordinating movements
2) reflex movements of head, eyes and body towards visual, auditory or tactile stimuli
3) aids in unconscious regulation and coordination of motor activities
what serves as a visual reflex center?
the midbrain
which cranial nerve innervates skeletal muscles of the neck and back?
accessory (XI)
which nerve is primarily a motor nerve with two branches; the spinal branch and the cranial branch
accessory (XI)
which cranial nerves are only sensory
1, 2 and 8 (vestibulochlear)
which cranial nerves are somatic motor and parasympathetic?
3
which cranial nerves are somatic motor only?
4 (trochlear), 6 (abducens), 11 (accessory) and 12
which cranial nerves are sensory and somatic motor?
5 (trigeminal)
which cranial nerves are sensory, somatic motor and parasympathetic?
7 (facial), 9 (glossopharyngeal) and 10
where in the brain is basal nuclei located?
1) midbrain
2) cerebrum
3) diencephalon
what connects parts of the cerebrum to other parts of the brain and spinal cord?
projection fibers
what connects areas of the cerebral cortex within the same hempisphere?
association fibers
what structures connect the cerebellum to the brainstem and allow communication between the cerebellum and other parts of the CNS
the peduncles
which cranial nerve is involved in reflexes necessary to maintain homeostasis?
vagus (X)
what part of the diencephalon is directly connected to the pituitary gland?
the hypothalamus
what area is located in the postcentral gyrus of the cerebral cortex?
the primary somatic sensory cortex
what is it called when water-soluble molecules of the blood plasma move across the blood-brain barrier?
symport
which nerves are involved in the sense of taste?
facial (VII), glossopharyngeal (IX) and vagus (X)
what nerve has the greatest cutaneous sensory distribution of any of the cranial nerves?
trigeminal (V)
what does the accessory nerve only have?
a spinal component
where is the excess CSF returned to?
the venous circulation
which portion of the spinal cord would be affected by a disease that damages myelin sheaths?
the white columns
if a person with polio lost use of their leg, which area of their spinal cord would you expect the virus-infected motor cell neurons to be?
in the anterior grey horns
what is the minimum number of neurons in a reflex arc?
2
which part of the brain stem contain cranial nerves V and VI and a respiratory center?
pons
where in the brain are basal nuclei located?
the cerebrum , medulla oblongata and midbrain
what is part of the epithalamus?
the pineal gland and thalamus
what is permeable across the BBB?
caffeine, glucose and oxygen
what type of reflex arc are interneurons used?
polysynaptic
