Exam 4 Anatomy 1: nervous system
Terms in this set (81)
4 characteristics of neruons
-Extreme longevity (lasts a person's lifetime)
-Amitotic, with few exceptions
-High metabolic rate: requires continuous supply of oxygen and glucose
-All have cell body and one or more processes
Define the different glial cells of the CNS
-Myelinate CNS axons
-provide structural framework
-Line ventricles (brain) and central canal (spinal cord)
-assist in producing, circulating, and monitoring cerebrospinal fluid
-maintain blood brain barrier
-provide structural support
-regulate ion, nutrient, and dissolved gas concentrations
-absorb and recycle neurotransmitters
-form scar tissue after injury
-remove cell debris, wastes, and pathogens by phagocytosis
Define the different glial cells of the PNS
-surround cell bodies in ganglia
-regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia
-surround all axons in PNS
-responsible for myelination of peripheral axons
-participate in repair process after injury
clusters of neuron cell bodies in CNS
clusters of neuron cell bodies in PNS
Bundles of neuron processes in CNS
Bundles of neuron processes in PNS
regions of brain and spinal cord with dense collections of myelinated fibers
mostly neuron cell bodies and nonmyelinated fibers
three or more processes (1 axon, others dendrites)
-Most common and major neuron type in CNS
two processes (1 axon, 1 dendrite)
-Rare (ex: retina and olfactory mucosa)
one T-like process (two axons)
Peripheral (distal) process: associated with sensory receptor
Proximal (central) process: enters CNS
Chemically gated channels
these open in response to a specific chemical stimulus (E.g: neurotransmitter, such as acetylcholine, or a hormone); these are specifically important a synapses
Voltage gated channels
these open in response to a change in the membrane potential; these are important in conducting action potentials along axons
Steps of a nerve impulse
-occurs when Na channels and K channels are closed
-occurs when Na channels open and K channels are closed
-occurs when Na channels are inactivated and K channels open
-occurs when Na channels are reset and K channels remain open
Explain salutatory conduction
Occurs only in myelinated axons and is about 30 times faster
-Myelin sheaths insulate and prevent leakage of charge
-Voltage-gated Na+ channels are located at myelin sheath gaps
-APs generated only at gaps
-Electrical signal appears to jump rapidly from gap to gap
a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure, chemical messengers, enable neurotransmission
a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter
the three catecholamines—dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline)—and histamine and serotonin. In terms of synthesis, packaging, release, and degradation, the amine neurotransmitters fall somewhere between the properties of the other small-molecule neurotransmitters and those of the neuropeptides.
building blocks of proteins, big part of giving cells their structures
Neuropeptides are small protein-like molecules (peptides) used by neurons to communicate with each other. They are neuronal signaling molecules that influence the activity of the brain and the body in specific ways. compounds that act as neurotransmitters, short chain polypeptides
rapid, predictable and involuntary response to stimuli
direct route from sensory neuron interneuron to effector neuron
-separates two hemispheres
-transverse cerebral hemispheres
-seperates cerebrum and cerebellum
a hollow part or cavity in an organ, in particular.
each of the two main chambers of the heart, left and right.
each of the four connected fluid-filled cavities in the center of the brain.
Primary motor area
-Generates neural impulses that control the execution of movement
-Pyramidal cells: large neurons that allow conscious control of precise, skilled, skeletal muscle movements
-Pyramidal (corticospinal) tracts: massive voluntary motor tracts formed from long pyramidal cell axons that project down spinal cord
-Somatotopy: all muscles of body can be mapped to area on primary motor cortex
-Directly anterior to primary motor cortex
-Helps plan movements - skilled motor activities
-Sequences basic motor movements into more complex tasks such as playing an instrument or typing
-Coordinates different muscle movements simultaneously or sequentially by sending signals to the primary motor cortex
-Present in one hemisphere (usually the left)
-Motor speech area that is responsible for the production of speech/language.
-involved in the comprehension or understanding of written and spoken language
upper motor neurons that originate in the cerebral cortex and terminate in the spinal cord (corticospinal) or brainstem (corticobulbar)
Primary visual area
-located on extreme posterior tip of occipital lobe
-Receives visual information from retinas
Visual association area
-surrounds primary visual cortex
-Uses past visual experiences to interpret visual stimuli (color, form, or movement)
Example: ability to recognize faces
Primary somatosensory area
-Located in postcentral gyri of parietal lobe, posterior to primary motor cortex
-Receives general sensory information from somatic sensory fibers in skin and proprioceptors of skeletal muscle, joints, and tendons
-Capable of spatial discrimination: identification of body region being stimulated
Somatosensory association area
-Posterior to primary somatosensory cortex
-Integrates sensory input from primary somatosensory cortex (temperature, pressure, etc) for understanding of object
-Determines size, texture, and relationship of parts of objects being felt
the tendency for some neural functions or cognitive processes to be specialized to one hemisphere rather than the other
The medial longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum
Property of the brain such that one side of the body is controlled by the opposite hemisphere of the brain: the left hemisphere controls the right side of the body, and the right hemisphere connects the left side of the body
either of two masses of gray matter lying between the cerebral hemispheres on either side of the third ventricle, relaying sensory information and acting as a center for pain perception
a region of the forebrain below the thalamus that coordinates both the autonomic nervous system and the activity of the pituitary, controlling body temperature, thirst, hunger, and other homeostatic systems, and involved in sleep and emotional activity
also known as the conarium or epiphysis cerebri, is a small endocrine gland in the vertebrate brain. The pineal gland produces melatonin, a serotonin derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone, hence its name
the part of the brainstem that links the medulla oblongata and the thalamus
It helps relay messages from the cortex and the cerebellum. Without the pons, the brain would not be able to function because messages would not be able to be transmitted, or passed along. It also plays a key role in sleep and dreaming
The medulla oblongata (or medulla) is located in the brainstem, anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions ranging from vomiting to sneezing
does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity
reticular activating system (RAS), is a set of connected nuclei in the brains of vertebrates that is responsible for regulating wakefulness and sleep-wake transitions
a complex system of nerves and networks in the brain, involving several areas near the edge of the cortex concerned with instinct and mood. It controls the basic emotions (fear, pleasure, anger) and drives (hunger, sex, dominance, care of offspring)
meninges of the brain
subarachnoid and subdural spaces
how it is formed:
The extra fluid puts pressure on the brain and can cause brain damage. It's most common in infants and older adults.
Hydrocephalus is characterized by head enlargement in infants. Adults and older children experience headache, impaired vision, cognitive difficulties, loss of coordination, and incontinence.
Treatment is often a tube (shunt) inserted surgically into a ventricle to drain excess fluid.
A build-up of fluid in the cavities deep within the brain
Meningitis is usually caused by a viral infection but can also be bacterial or fungal. Vaccines can prevent some forms of meningitis.
Symptoms include headache, fever, and stiff neck.
Depending on the cause, meningitis may get better on its own, or it can be life-threatening, requiring urgent antibiotic treatment
Inflammation of brain and spinal cord membranes, typically caused by an infection
Inflammation of the brain, often due to infection
The infection may be bacterial or viral. In some cases encephalitis, may be the result of an immune system disorder.
Mild cases may cause no symptoms or mild flu-like symptoms. Severe cases can be life-threatening. Immediate medical attention is needed for symptoms such as confusion, hallucinations, seizures, weakness, and loss of sensation.
In addition to addressing the underlying cause, treatments include symptomatic relief and supportive care
-Fifth leading cause of death in US
Leading cause of serious long-term disability in the US
¾ of all strokes occur in people > 65
Biggest risk factors:
During a stroke, every second counts. Fast treatment can reduce the brain damage that stroke can cause. Signs and symptoms of stroke include sudden:
-Numbness or weakness in the face, arm, or leg, especially on one side of the body
-Confusion, trouble speaking or difficulty understanding speech
-Trouble seeing in one or both eyes
-Trouble walking, dizziness, loss of balance, or lack of coordination
-Severe headache with no known cause
Call 9-1-1 immediately if any of the above symptoms are experienced.
If you think someone may be having a stroke, act F.A.S.T. and do the following simple test:
F - Face: Ask the person to smile. Does one side of the face droop?
A - Arms: Ask the person to raise both arms. Does one arm drift downward?
S - Speech: Ask the person to repeat a simple phrase. Is their speech slurred or strange?
T - Time: If you observe any of these signs, call 9-1-1 immediately
Note the time when any symptoms first appear. Some treatments for stroke only work if given within the first 3 hours after symptoms appear.
Ischemic stroke - obstruction within a blood vessel supplying blood to the brain (87% of all stroke cases)
Hemorrhagic stroke - weakened blood vessel ruptures (aneurysm) but most common cause is uncontrolled hypertension
Transient ischemic attack (TIA) - caused by a temporary clot; "mini stroke"
Cerebrovascular accident: The sudden death of some brain cells due to lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain
A brief stroke-like attack that, despite resolving within minutes to hours, still requires immediate medical attention to distinguish from an actual stroke.
A TIA may be a warning sign of a future stroke.
Symptoms include weakness on one side of the body, vision problems, and slurred speech. These are transient and often resolve within 24 hours.
Treatment includes medication, surgery, and healthy lifestyle changes.
-virus that may cause paralysis
-preventable by vaccine
-treatment can help, but this condition cannot be cured
-spreads through contaminated food and water or contact with an infected person
-requires a medical diagnosis
-lab tests or imaging always required
-Burning or prickling sensation usually felt in hands, feet, arms or legs
-Caused by damage to dorsal roots or sensory tracts
spinal cord or ventral roots are injured
only upper motor neurons of primary motor cortex are damaged (spinal reflex may continue to stimulate muscles irregularly)
T1 & L1 - both lower limbs affected
cervical region - all four limbs are affected
respond to touch, pressure, vibration, and stretch
sensitive to changes in temperature
-Transmit signals of chemical, thermal or mechanical stimulus
-Vanilloid receptor: protein in nerve membrane is main player
-Acts as ion channel that is opened by heat, low pH, chemicals (example: capsaicin in red peppers)
-Itch receptors in dermis: can be triggered by chemicals such as histamine
Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles
-Inform brain of body position/movement
small receptors involved in discriminative touch; found just below skin, mostly in sensitive and hairless areas (fingertips)
large receptors respond to deep pressure and vibration when first applied (then turn off); located in deep dermis
respond to deep and continuous pressure; located in dermis
loose connective tissue that encloses axons and their myelin sheaths (Schwann cells)
tough fibrous sheath around all fascicles to form the nerve
-Sensory nerves of smell
-Pass through cribriform plate of ethmoid bone
-Fibers synapse in olfactory bulbs
-Pathway terminates in primary olfactory cortex
-Purely sensory (olfactory) function
-Arise from retinas; really a brain tract
-Optic radiation fibers run to occipital (visual) cortex
-Purely sensory (visual) function
-Fibers extend from ventral midbrain through superior orbital fissures to four of six extrinsic eye muscles
-Function in raising eyelid, directing eyeball, constricting iris (parasympathetic), and controlling lens shape
-Fibers from dorsal midbrain enter orbits via superior orbital fissures to innervate superior oblique muscle
-Primarily motor nerve that directs eyeball
-Largest cranial nerves; fibers extend from pons to face
-Ophthalmic (V1) passes through superior orbital fissure
-Maxillary (V2) passes through foramen rotundum
-Mandibular (V3) passes through the foramen ovale
-Convey sensory impulses from various areas of face (V1 and V2)
-Supply motor fibers (V3) for mastication
-Afferent fibers from hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass from inner ear through internal acoustic meatuses and enter brain stem at pons-medulla border
-Mostly sensory function; small motor component for adjustment of sensitivity of receptors
-Formerly auditory nerve
-Only cranial nerves that extend beyond head and neck region
-Fibers from medulla exit skull via jugular foramen
-Most motor fibers are parasympathetic fibers that help regulate activities of heart, lungs, and abdominal viscera
-Sensory fibers carry impulses from thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds of posterior tongue and pharynx
-Fibers from medulla exit skull via hypoglossal canal
-Innervate extrinsic and intrinsic muscles of tongue that contribute to swallowing and speech
ALS(Lou Gehrig's disease)
A nervous system disease that weakens muscles and impacts physical function
In this disease, nerve cells break down, which reduces functionality in the muscles they supply. The cause is unknown.
The main symptom is muscle weakness.
Medication and therapy can slow ALS and reduce discomfort, but there's no cure
A disorder of the central nervous system that affects movement, often including tremors
Nerve cell damage in the brain causes dopamine levels to drop, leading to the symptoms of Parkinson's.
Parkinson's often starts with a tremor in one hand. Other symptoms are slow movement, stiffness, and loss of balance.
Medications can help control the symptoms of Parkinson's
An inherited condition in which nerve cells in the brain break down over time
It typically starts in a person's 30s or 40s.
Usually, Huntington's disease results in progressive movement, thinking (cognitive), and psychiatric symptoms.
No cure exists, but drugs, physical therapy, and talk therapy can help manage some symptoms
A progressive disease that destroys memory and other important mental functions
Brain cell connections and the cells themselves degenerate and die, eventually destroying memory and other important mental functions.
Memory loss and confusion are the main symptoms.
No cure exists, but medications and management strategies may temporarily improve symptoms