Exam 3 Flashcards
How does the nervous system communicate with the other systems of the body?
Sensory input, integration, motor output
Motor output goes to an effector. What can be the effector?
- Smooth muscle, skeletal muscles and cardiac muscles
- Glands
What makes up the CNS?
Brain and spinal chord
What makes up the PNS?
Cranial and spinal nerves
The _______ division carries out the response
motor (efferent)
What are the two divisions of the motor division? describe them
- Somatic (voluntary): skeletal muscles
- Autonomic (involuntary): cardiac and smooth muscle, glands
What are the two arms of the autonomic division?
Parasympathetic and sympathetic
T / F : neuroglia outnumber neurons by a factor of 10
T
How many kinds of neuroglia are there?
6
What are the cells of the nervous system?
Neuroglia and neurons
4 of the 5 kinds of neuroglia reside in the ______
CNS
__________ are the most abundant and versatile neuroglia
Astrocytes
________ cells are phagocytes that defend CNS cells and monitor the health of the neuron
Microglial
_________ cells line cerebrospinal fluid-filled cavities and have cilia
Ependymal
_________ have processes that form myelin sheaths around CNS nerve fibers
Oligodendrocytes
Any neuron that has a myelin sheath has a _______ rate of conduction
faster
What are the 2 neuroglia of the PNS?
Satellite and Schwann cells
Satellite cells are analogous to
astrocytes
Schwann cells are analogous to
oligodendrocytes
Where is gray matter found within the brain? White matter? How about in the spinal cord?
- Gray matter is usually made up of cell bodies and their associated dendrites
- White matter is white from myelinated axons
- Gray matter in the brain: surrounds the cerebrum, known as the cortex (cerebellar and cerebral cortex) and is also found in the brain stem; gray matter is superficial
- White matter in the brain: found in deeper tissues of the brain (subcortical); white matter is deep
- Gray matter in the spinal cord: within the white matter
- White matter in the spinal cord: towards the outside of the spinal cord
Differentiate between tracts and nerves; nuclei and ganglia (what do they consist of and where are each located?)
- Tracts: bundles of nerve fibers in the central nervous system
- Nerves: bundles of nerve fibers in the peripheral nervous system
- Nuclei: clusters of neuron cell bodies in the central nervous system
- Ganglia: clusters of neuron cell bodies in the peripheral nervous system
Contrast sensory and motor neurons.
- Sensory (afferent): carry signals to your brain/CNS to help you touch, taste, smell and see
- Motor (efferent): carry signals to your muscles or glands/PNS to help you move and function
Where are interneurons found and what is their function?
- Found in CNS
- Function: aka association neurons, complete the communication pathway between sensory and motor neurons
What are the parts of a neuron and the functions of these parts
- 3 main parts: cell body, dendrites, axon
- Cell body: contains nucleus and nucleolus, where all cellular products are made as well as where protein synthesis and transport take place, etc. *housekeeping tasks, keeps neuron alive
- Dendrites: short, branched structures that receive incoming signals/information from other neurons
- Axon: send/transmit signal away from cell body, has Schwann cells surrounding it that form the myelin sheath, exposed nodes (Nodes of Ranvier)
Which structural type of neuron do we have the most of?
Multipolar neuron
What are the different types of sensory receptors?
- Free nerve endings: pain reception
- Meissner’s corpuscle: fine touch receptor
- Lamellar corpuscle: deep pressure receptor
- Golgi tendon organ: proprioceptor of tendons (detects stretch/tension)
- Muscle tendon: proprioceptor of muscles (detects stretch/tension)
What is the resting membrane potential and describe how the resting membrane potential is achieved.
- RMP: -70 mV
- Maintained because the polarized membrane is more permeable to K+ than Na+, meaning more K+ move out than Na+ in
Contrast polarized, depolarized and repolarized.
- Polarized: more negative inside the membrane relative to the outside (neuron at rest)
- Depolarized: inside is now more positive and outside is less positive
- Repolarized: return to resting state, outflow of positive ions
Describe what happens when a neuron is stimulated (i.e. an action potential and the conduction of the action potential)
- Local depolarization
- Ion channels open
- Electrical impulse = nerve impulse = action potential (result of Na+ flowing in, will get AP if stimulus is strong enough)
Describe the phases of the action potential: stimulus, depolarization, repolarization and back to rest
- Stimulation: initiates local depolarization, Na+ ions diffuse into a “patch” of the cell
- Depolarization: if stimulus is strong enough, depolarization spreads, resulting in an action potential, which is propagated along the length of the neuron membrane
- Repolarization: caused by opening of K+ channels and outflux of K+
- Back to rest: back to RMP via Na+/K+ resetting ionic conditions
What happens at a chemical synapse?
- AP is transmitted to axon terminal
- Upon arrival of AP, Ca+ ion channels in the axon terminals open
- Ca+ channels opening causes the exocytosis of vesicles filled with chemicals (neurotransmitter)
- NT diffuses across/through the synaptic cleft and binds its receptor (ion channels) on the receiving cell membrane
- If enough of NT opens enough ion channels, depolarization occurs, leading to the generation of another AP!
Define reflex arc
Involuntary, rapid, predictable response to stimulus
What are the 5 elements of a reflex arc?
- Receptor
- Sensory neuron
- Integration center
- Motor neuron
- Effector
Contrast a 2 vs 3 neuron reflex arc
- 2 neuron reflex arc: (think of the patellar tendon reflex) contains only sensory and motor neurons that synapse directly together
- 3 neuron reflex arc: contains all 3 types of neurons (sensory, motor and interneurons)
Describe the sulci/gyri/fissures
- Sulci: the valleys of the folds/wrinkles of the brain
- Gyri/gyrus: a fold or hill, the high parts of the wrinkles of the brain
- Fissures: divide the brain into lobes
Describe hemispheres
The left and right hemispheres are separated by the longitudinal fissure
What are the four lobes of the brain?
Frontal, parietal, occipital and temporal
Describe the cerebral cortex
- Outermost, thin layer of gray matter (about 1/8 of an inch in thickness), very active
- Involved in speech, memory, logic, emotional responses, consciousness, interpretation of situations and voluntary movements
Describe the corpus callosum
Thick band of white matter that connects the cerebral hemispheres
Describe basal nuclei
Islands of gray matter, functional in helping with motor activity, enabling you to start and stop a particular motion, influence motor activity or movement, deep within white matter of cerebrum
Describe the prefrontal cortex
Involved in working memory, judgement, problem solving, comprehension, important cognitive area of brain
What are the roles in movement played by the primary motor cortex?
Where all voluntary skeletal muscle originates
What are the roles in movement played by the premotor cortex?
Where the planning of movements occurs, repetitive movements are learned and stored here
What are the roles in movement played by the cerebellum?
Balance, equilibrium, coordination, posture
What are the roles in movement played by the basal nuclei?
Islands of grey matter, help to regulate voluntary motor activities by modifying instructions sent to the skeletal muscles by the primary motor cortex
What are the roles in movement played by the frontal eye field?
Control over 6 extrinsic eye muscles
What are the roles in movement played by Broca’s area?
- In charge of motor speech
- Involved in moving face, tongue, forming words, etc.
What happens in the sensory areas of the cerebral cortex? What are the association areas?
- Sensory information is sent to the area and then neurons on the outside of that area help to interpret the incoming information
- Anterior association area: higher intellectual reasoning and comprehension as well as socially acceptable behaviors
- Posterior association area: pattern and face recognition, also contains speech area
Be able to identify the location and function of the following: thalamus, hypothalamus, mammillary bodies, pineal gland, reticular formation and RAS!
- thalamus: oval shaped, central relay center for senses, often called the gateway to the sensory cortex, because that sensory information comes in first to the thalamus which then relays it on to the somatic sensory portion, etc.
- hypothalamus: beneath/below the thalamus, important autonomic nervous system regulatory center. Important for body temp control, hunger and thirst center, fluid balance, hormones, etc.
- mammillary bodies: just behind pituitary gland, important for memory
- pineal gland: important for daily sleep and wake cycles, secretes melatonin
- reticular formation: runs the entire length of the brain stem, helps to coordinate a lot of activities within the brain
- RAS: reticular activating system, a part of the reticular formation. Involved in consciousness and arousal of cerebral cortex (when you wake up or maybe keeping you asleep), helps to filter sensory information
Describe the protective layers around the brain
- Dura mater, arachnoid mater and pia mater make up the meninges
- Dura mater: double layer membrane of connective tissue, protects the brain on the outside
- Arachnoid mater: wispy middle layer
- Pia mater: delicate, nourishing, lots of blood vessels
What are the numbers of the different groups of spinal nerves (cervical, etc.)? How does this differ from the numbers of bones in each segment of the vertebral column?
Cervical
- spinal nerves: 8
- vertebrae: 7
Thoracic
- spinal nerves: 12
- vertebrae: 12
Lumbar
- spinal nerves: 5
- vertebrae: 5
5 sacral spinal nerves
1 coccygeal spinal nerve
What are the 3 parts of the brain stem from superior to inferior and their functions
- Midbrain: has several reflex centers for reflex and vision
- Pons: means bridge, has long tracts that act as a bridge/form connection between the upper parts of the brain and your medulla. Also contains an important respiratory center called the pontine respiratory center
- Medulla: major, visceral (organ) control center. Damage to this is often fatal as many organs rely on it/are controlled by it (heart rate, respiratory rate, blood pressure, swallowing, vomiting)
Describe how the spinal nerves associated with each numbered vertebral bone exit the vertebral column (above or below).
- C1 nerve exits above C1
- C2-7 nerves exit above corresponding vertebrae
- C8 exits below C7 vertebra
- all thoracic and lumbar nerves than exit below their corresponding vertebrae
Define/describe the conus medullaris
the terminal end of the spinal cord (~L1)
Define/describe the intervertebral foramen
serves as the doorway between the spinal canal and periphery
Define/describe the vertebral foramen
- the foramen (opening) formed by the anterior segment (the body), and the posterior part, the vertebral arch
- begins at cervical vertebra #1 and continues inferior to lumbar vertebra #5
Define/describe the cauda equina
The collection of spinal nerves at the inferior end of the vertebral canal
At what level does the spinal cord taper off?
~L1-L2
Describe the structure/function of the ascending and descending pathways between brain and spinal cord (use lateral corticospinal tract as an example)
- Ascending: sensory, taking information to the brain
- Descending: motor pathways, taking information to spinal cord/body
- Lateral corticospinal tract: descending (motor), synapse in the anterior horn of SC
What are the 12 pair of cranial nerves?
- C1: olfactory
- C2: optic
- C3: oculomotor
- C4: trochlear
- C5: trigeminal
- C6: abducens
- C7: facial
- C8: vestibulocochlear
- C9: glossopharyngeal
- C10: vagus
- C11: accessory
- C12: hypoglossal
Describe the structure of a spinal nerve
- Ventral and dorsal root to spinal nerve
- Ventral root: motor component
- Dorsal root: sensory component
Describe the role of the ANS and contrast the two arms
- Role: involuntary movements
- Two arms: parasympathetic and sympathetic
- Parasympathetic: rest and digest
- Sympathetic: fight or flight
What are the ANS effectors (3 of them)?
smooth muscle, cardiac muscle, glands
Describe dual innervation by the ANS
- to be both parasympathetic and sympathetic
- most organs are dually innervated
T / F : all spinal nerves are mixed nerves
T
Together with the brain stem, the __________ oversees all subconscious, autonomic functions.
diencephalon
The cell bodies of sensory neurons whose fibers enter the spinal cord are found in the __________.
dorsal root ganglion
The __________ area, which allows us to consciously move our skeletal muscles, is anterior to the central sulcus in the __________ lobe.
primary motor, frontal
__________ is considered the major relay station for ascending sensory information
The thalamus
The deep groove that separates the two hemispheres of the cerebrum is called the __________.
longitudinal fissure
The __________ division of the autonomic nervous system generates the fight-or-flight response in extreme circumstances.
sympathetic
Damage to which cranial nerves may impair the sense of taste?
- C7: facial
- C9: glossopharyngeal
The cerebellum aids in maintenance of __________.
posture and balance
The three connective tissue membranes covering and protecting CNS structures are collectively known as the __________. The __________ is the outermost, leathery layer.
meninges; dura mater
Select the substances that the blood-brain barrier prevents from entering brain tissue.
- Proteins
- Urea
- Glucose
- Alcohol
urea, proteins
The corpus callosum connects the __________.
right and left cerebral hemispheres
The __________ produce cerebrospinal fluid.
choroid plexuses
The autonomic nervous system controls…
smooth muscle, cardiac muscle, and glands
The somatic nervous system controls…
skeletal muscle
The central nervous system includes…
the brain and spinal cord
The peripheral nervous system includes…
spinal nerves and cranial nerves
Describe the role and circulation of the CSF
- CSF is made in the choroid plexuses dangling from the ventricles
- CSF flows from lateral ventricle, into third, through the cerebral aqueduct and into the fourth and then into the subarachnoid space
- Is able to circulate due to cilia of ependymal cells
- Role: protects the brain by providing cushioning
Describe the flow of information in terms of the dorsal and ventral roots
Information goes outward from ventral root and comes inward via the dorsal root
Damage to _______ typically results in a coma because the cortex cannot be aroused
RAS
Why are the Nodes of Ranvier important?
They are where the nerve impulses will jump (in a myelinated axon), which helps to increase the speed of an electrical impulse
Where are nerve impulses generated?
Axon hillock
________ communicate with the next cell (muscle cell, gland cell, another neuron, etc.)
Axon terminals
Clusters of cell bodies in the CNS are known as _______, while clusters of cell bodies in the PNS are known as ________
nuclei, ganglia
Bundles of nerve fibers/neuron processes are known as _______ in the CNS and ______ in the PNS
tracts, nerves
What are the functional classifications of neurons?
Sensory, motor and interneurons
What are the structural classifications of neurons?
Multipolar, bipolar, unipolar
Where are bipolar neurons typically found?
Eye, nose, etc.
Where are unipolar neurons typically found?
Some sensory organs in PNS
Are neurons or muscle cells more irritable?
Neurons!
Describe a neuron at rest
- Unstimulated
- RMP (-70 mV, slightly negative inside, slightly positive outside)
- Membrane is polarized
At rest, _______ (more or less) K+ diffuses outward than Na+ diffuses inward
more
In what ways does neurotransmitter action end?
- Diffuses away
- Broken down via enzymatic activity
- Taken back up by transmitting neuron
