Flashcards in Exam 2 Part four Deck (103):
Resting potential is
The imbalance of electrical charge that exists between the interior of electrically excitable nerve cells and their surroundings.
The difference in charge between the interior & exterior of the cell is called
Resting membrane potential
For the nerve impulse, what does the resting membrane potential have?
The exterior of the cell has a net positive charge and the interior has a net negative charge
During depolarization what voltage-gated ion channel opens first and second?
Na+ gates open before K+ gates
Depolarization occurs because
More Na+ diffuse into the cell than K+ diffuse out of it
True or false: The sodium-potassium pump is involved in establishing the resting membrane potential
True or false: The nerve impulse is an electrical current that travels along dendrites or axons
An action potential occurs when?
A neuron is conducting a nerve impulse
The state during which no nerve impulse is being conducted
State during which the neuron is actively involved in conducting a nerve impulse
The resting potential is at?
The difference in ion displacement and thus the resting potential is largely maintained by a protein channel called the
The Na+/K+ pump is
Powered by ATP, it actively pumps Na+ ions out of the cell and K+ ions into the cell
The point at which increasing stimuli trigger the start of an afferent nerve impulse
The all-or-nothing for a nerve impulse means that
The ion channels are either open or closed; there is no half-way position
Define Depolarization for a nerve impulse
Reversal of the resting potential in excitable cell membranes when stimulated
Active transport for a nerve impulse is
When a neuron is at rest a charge difference is maintained between the inside and outside of the cell, this charge difference is produced & maintained largely by active transport using sodium-potassium pumps
What is diffusion of a nerve impulse?
When the K+ (potassium) and Na+ (Sodium) diffuse in and out of the neuron during an action potential
Monosynaptic reflex is
The simplest of all reflexes. The sensory axons synapse directly on the motor neurons, whose axons project to the effector
Give an example of a monosynaptic reflex
The patellar reflex, which physicians use to assess the functioning of the spinal cord
Polysynaptic reflexes have
More complex neural pathways that exhibit a number of synapses involving interneurons within the reflex arc. More prolonged delay.
An example of a polysynaptic reflex is
The crossed-extensor reflex, the reflex that supports postural muscle activity when you withdraw your foot from a painful stimulus
Effectors can be
1) A muscle, gland, or organ capable of responding to a stimulus, especially a nerve impulse
2) A nerve ending that carries impulses to a muscle, gland, or organ and activates muscle contraction or glandular secretion
Structures that detect stimuli
A cell, a group of cells, or an organ that produces a secretion for use elsewhere in the body or in a body cavity or for elimination from the body
Considering "the all-or-none" rule of muscle contraction, how is it that we are able to have smooth & refined body movements?
While the muscle fibers obey all the all-or-none principe, the force and precision of muscle movement can be varied, depending on how many muscle fibers and motor units are activated
Muscle fatigue means
That you have exhausted the muscle past the point of it being able to use aerobic respiration
A form of cellular respiration that requires oxygen in order to generate energy
Muscle belly (body) is
Main region that shortens & thickens when it contracts, Creates the Action
If a muscle can only contract (shorten in length) explain how it is that we can "push" an object. Give an example
By levers. Olecranon process
What is the order of skeletal muscle development?
Describe the relationship between mesoderm, somites & myotomes in skeletal muscle development
1) Skeletal muscle tissue formation is initiated during the fourth week of development from blocks of paraxial mesoderm that form somites
2) Cells w/in a somite differentiate into 3 distinct regions; one being myotome which gives rise to skeletal muscles
How do muscles maintain homeostasis?
They help regulate our body temperature
The autonomic nervous system (ANS)
Also called the autonomic motor. It innervates internal organs & regulates smooth muscle, cardiac muscle, & glands without our control, Also known as the visceral motor system or the involuntary nervous system. Has two further subdivisions; parasympathetic and sympathetic
Fight-or-flight response is
A physiological reaction in response to stress, characterized by an increase in heart rate and blood pressure, elevation of glucose levels in the blood, and redistribution of blood from the digestive tract to the muscles. These changes are caused by activation of the sympathetic nervous system by epinephrine (adrenaline), which prepares the body to challenge or flee from a perceived threat
(Sympathetic nervous system)
Gray matter in the brain is
Houses motor neuron & interneuron cell bodies, dendrites, telodendria, and unmyelinated axons
The white matter in the brain is
Derives its color from the myelin in the myelinated axons
Rest-and digest responses are
When parasympathetic activity dominates, healing and regeneration occur. The body performs activities like digesting, detoxifying, eliminating, and building immunity
What is collateral ganglia?
Any of the sympathetic ganglia located in front of the vertebral column, outside the sympathetic chain, close to the viscera and arteries. It is mainly involved in the innervation of abdominal and pelvic viscera.
The midbrain. Only primary vesicle that does not form a new secondary vesicle
Arises from the prosencephalon & eventually forms the cerebrum
What is diencephalon
Arises from the prosencephalon & eventually forms the thalamus, hypothalamus, & epithalamus
The rhombencephalon is
The prosencephalon is
The metencephalon arises from
The rhombencephalon & eventually forms the pons and cerebellum
The myelencephalon derives from
The rhombencephalon & eventually forms the medulla oblongata
The cerebrum is the location of
conscious thought processes & the origin of all complex intellectual functions. Identified as two large hemispheres on the superior aspect of the brain
When the neuroectoderm undergoes dramatic changes to form nervous tissue structures
What is the primary germ layer derivative of neurons: brain & spinal cord, Glial cells: brian and spinal cord?
A bulging region on the anterior part of the brainstem that forms from part of the metencephalon
The thalamus refers to
Paired oval masses of gray matter that lie on each side of the third ventricle. Forms the superolateral walls of the third ventricle
The hypothalamus is the
Anteroinferior region of the diencephalon.
Three thick tracts that link the cerebellum with the brainstem
The medulla oblongata is
Formed from the myelencephalon. The most inferior part of the brainstem & is continuous with the spinal cord inferiorly
The central nervous system forms primarily from?
The embryonic neural tube
Towards the tail
Relating to the head or the head end of the body. Situated on, in, or near the head. Cephalic is synonymous with cranial, relating to the cranium or head
Neural groove is
The gutterlike groove formed in the midline of the embryo's dorsal surface by the progressive elevation of the lateral margins of the neural plate, resulting in the formation of the neural tube. Also called medullary groove
A small protuberance, especially one of two pairs in the roof of the midbrain, involved respectively in vision and hearing
Nerve growth factor is
A protein that promotes development of the sensory and sympathetic nervous systems and is required for maintenance of sympathetic neurons
A protein that stimulates the growth of sympathetic and sensory nerve cellS
Nerve growth factor
Describe neuron repair following damage
Why do neurons usually not repair in the CNS?
Limited due to several factors
1) Oligodendrocytes do not release a nerve factor, they inhibit axon growth by producing and secreting several growth inhibitory molecules
2) Large numbers of axons crowded within the CNS complicates regrowth activities
3) Astroctyes & connective tissue coverings can form scar tissue that obstructs axon regrowth
Neurotransmitter of the postganglionic fibers in the sympathetic division of the autonomic system
Chemical stored at the ends of axons that is responsible for transmission across a synapse
What are the 12 cranial nerves?
The function and sensory/motor function for Olfactory cranial nerve
* Odor detection
The function and sensory/motor function for optic cranial nerve
The function and sensory/motor function for oculomotor, trochlear, and abducens cranial nerves
Function and sensory/motor function for trigeminal cranial nerve
Function and sensory/motor function for facial cranial nerve
*Motor to face
*Sensory from tongue
Function and sensory/motor function for vestibulocochlear cranial nerve
* Hearing and balance
Function and sensory/motor function for glossopharyngeal cranial nerve
Function and sensory/motor function for vagus cranial nerve
Function and sensory/motor function for accessory cranial nerve
* Neck and upper back
Function and sensory/motor function for hypoglossal cranial nerve
Threshold level is
At the base of the hillock, or trigger zone, the stimulus must reach a specific threshold level in order to generate an action potential. At the threshold, a positive feedback look of Na+ influx will initiate
A damaged axon can regenerate if
At least some neurilemma remains
PNS axon regeneration depends upon 3 factors
1) Amount of damage
2) Neurolemmocyte secretion of nerve growth factors to stimulate outgrowth of severed axons
3) The distance between the site of the damaged axon and the effector organ
How do neurolemmocytes help repair a damaged axon?
Through a regeneration process called Wallerian degeneration
A large portion of the brain, serving to coordinate voluntary movements, posture, and balance. in back of and below the cerebrum and consists of two lateral lobes and a central lobe
Where are ganglia and nuclei located?
In the central nervous system, a collection of neuron cell bodies is called a nucleus.
In the peripheral nervous system, a collection of neuron cell bodies is called a ganglion
What does ganglia contain?
Mass of nerve tissue; a group of nerve cell bodies, especially nerve cells external to the brain or spinal cord
What does nuclei contain?
A mass of nerve cells in the brain or spinal cord in which nerve fibers form connections
Gray matter in the spinal cord is dominated by
The dendrites and cell bodies of neurons and glial cells and unmyelinated axons
White matter in the spinal cord is composed of
Primarily myelinated axons
Where is gray matter in the spinal cord located?
Centrally located, it resembles a letter H or a butterfly
The gray matter in the spinal cord may be subdivided into
Anterior horns, lateral horns, posterior horns, and the gray commissure
Gray Commissure is
A horizontal bar of gray matter that surrounds a narrow central canal. Contains unmyelinated axons and serves as a communication route between the right and left sides of the gray matter
White commissure is
A narrow band of white matter that crosses the midline of the spinal cord posterior to the central canal and posterior gray commissure
Gray matter and white matter in the brain
(Gray on outside, white in middle
* Gray matter: houses motor neuron and interneuron cell bodies, dendrites, telodendria, and unmyelinated axons
* White matter: Derives its color from myelin in the myelinated axons. Lies deep to the gray matter of the cortex. Within masses of white matter, the brain contains clusters of gray matter (cerebral nuclei)
What is ganglionic neuron?
autonomic motor neuron that has its body in a peripheral ganglion and projects its (postganglionic) axon to an effector
Ganglion Of Sympathetic Trunk are
Clusters of postsynaptic neurons located at intervals along the sympathetic trunks, including the superior cervical, middle cervical, and cervicothoracic ganglion, the thoracic, lumbar, and sacral ganglia, and the ganglion impar
Pertaining to thoracic and lumbar vertebrae
A therapy that uses gentle manual pressure applied to the skull, spine, and membranes to restore rhythmic flow to the craniosacral system, which includes the brain, spinal cord, cerebrospinal fluid, and surrounding membranes.
Sympathetic Postganglionic Neurons
Postganglionic fibers are long and unmyelinated.
Sympathetic Preganglionic Neurons
Preganglionic fibers are short and myelinated.
Overview of parasympathetic pathways
Preganglionic axons from the brain & spinal cord innervate the viscera in the head, neck and trunk
Overview of the sympathetic pathways
The right sympathetic
Ganglia in sympathetic is
Closer to CNS
Parasympathetic preganglionic neurons
Preganglionic fibers are long and myelinated.
Parasympathetic postganglionic neurons
Postganglionic fibers are short and not myelinated