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The cerebrum has four major lobes. The frontal, the parietal, the temporal, and the occipital lobe. Frontal lobe. This is the largest lobe and is located in front of the brain. This part of the brain are mainly for "higher brain functions". The main functions of this lobe are for concentration and problem solving, abstract thought, storage of information or memory and for motor function. It is also responsible for judgment (whether actions or events are good or bad), a person's affect and personality, for overriding or suppressing impulses or "impulse control", and sexual and social behavior. This lobe also contains the "Broca's Area", wherein its function is for the motor control of a person's speech.
Parietal lobe. The lobe posterior to the frontal lobe. Its main function is for relaying interpretations of previously analyzed sensory information and relays it to other cortical areas. This is also responsible for the person's awareness of the body's position in space and awareness of body parts (proprioception). It is also involved in size and shape discrimination, texture discrimination, and right and left orientation. This lobe is divided into two hemispheres, the left and the right. The left hemisphere is mainly for symbolic functions of languages and math while the right is for visual-spatial functions (e.g. for location of self, direction to other places).
Temporal lobe. This lobe is inferior to the parietal and frontal lobes. Its function is mainly for auditory perception and plays a significant role in memory of sound, and understanding/interpretation of language and music. This lobe also contains the hippocampus, in which is responsible for maintaining long-term memory.
Occipital lobe. This is located posterior to the parietal lobe. This lobe's function is mainly for visual interpretation and visual memory. This is also responsible for the occurrence of dreams in people.
Other lobe associated with the cerebrum:
Limbic lobe. is an arc-shaped region of the cortex on the middle surface of each cerebral hemisphere of the brain, which consists of parts from the frontal, temporal and parietal lobes. This has been found to contribute for the function of olfaction, or sense of smell.
How does the aging process impact the neurological system?
The aging process poses a great impact on the body, as well as the neurological system. Almost all of the neurological functions and their roots are diminished during the latter stage of a person's life.
In the central nervous system, there are occurrences of loss of neurons. This leads to a decrease in number of neurotransmitters and synapses, thereby resulting in slowed nerve conduction and response time. The brain weight decreases and its ventricles increase its size to maintain cranial volume (as explained by the Monro-Kellie principle, to maintain the volume inside the cranium). Reduction of cerebral blood flow and metabolism are also noted, causing slower mental functioning. Memory, language, and judgement capacities are still intact, only it takes time to be processed due to slower functioning of the brain. Delirium and dementia shouldn't be considered as a normal aging effects, since this signifies presence of underlying causes. Assessment and diagnosis should be done promptly.
Thermoregulation becomes less efficient as well. Reaction to painful stimuli decreases, therefore predisposing them to risk for serious burns or frostbites because they also have slow responses to extremes in temperatures. Complaints of pain may be more serious than it is described, therefore, assessment should be done carefully and thoroughly.
In the peripheral nervous system, myelin is lost which results to decrease in velocity conduction in some nerves. Reduced nerve input into muscles promotes reduction in muscle bulk, and sometimes is atrophied. Decrease in strength and agility is also noted, with increased reaction time.
Gait is slowed and wide based. Balance difficulties results from degeneration of the vestibular system of the inner ear, cerebellum, and proprioceptive pathways, which are all responsible for maintenance of balance. This increases their risk for injuries and falls, which can predispose to cerebral impairments, fractures, etc. Decrease of DTR's and hypothalamic function modification occurs that affects sleep cycles.
Visual and hearing acuity decreases, caused by degeneration of its nerve cells. Visual degeneration is manifested by sensitivity to glare, decrease in peripheral vision, and a constricted visual field. Dark re-orientation takes a longer time for the elderly, therefore, increases their risk of injury and accidents in dark rooms.
Hearing impairment can cause confusion, anxiety, misinterpretation of environment, disorientation, feelings of inadequacy and isolation. This impairment affects the social, emotional, and mental aspect of an aging person.
Loss of appetite is caused by taste bud atrophy and degeneration of olfactory bulb, affecting taste and smell, respectively. Tactile sensation also decreases because sensory receptors in the body degenerate as well. Location of the body and its parts may be difficult as well due to the decrease in proprioceptive pathways. This can cause confusion as to where pain is felt during assessment.
ANS responses also decrease, as well as pupillary responses in the presence of cataracts.
Compare and contrast the sympathetic and parasympathetic nervous systems in terms of function.
SYMPATHETIC NERVOUS SYSTEM
PARASYMPATHETIC NERVOUS SYSTEM
Body's "flight or fight" response
Neurotransmitters are epinephrine and norepinephrine
Sympathetic impulses increases greatly under stress from either emotional or physical origins
Pupils are dilated to be able to more light during stressful situations
Blood vessels dilate to be able to deliver blood faster to other organs of the body to improve functionality
Bronchioles dilate because oxygen demand increases
Heartbeat increases to be able to deliver more blood to other parts of the body especially the brain
Sweat increases due to increased activity of the body
Glycogenolysis occurs to increase the body's fuel or energy for stressful events
Parasympathetic impulses take over during quiet, nonstressful conditions "rest and digest"
Neurotransmitter is acetylcholine
Its function is in opposition to the sympathetic nervous system's function
Constricts pupils to allow closer vision
May dilate blood vessels in the GI tract to increase blood flow which is important for food consumption, since this increases metabolic demands of the body by the gut.
It also allows proper absorption of nutrients
Peristalsis increases and sphincters relax to promote release of bodily wastes
This also stimulates sexual arousal
Rate and Force of Heartbeat
Bld vessels in Heart muscle
Bld vessels in skeletal muscle
No direct effect
Bld vessels in abdominal viscera and the skin
No direct effect
Rate of Breathing
Peristaltic movements of digestive tube
Muscular sphincters of digestive tube
Secretion of salivary glands
Thick, viscid saliva
Thin, watery saliva
Secretion of stomach, intestine and pancreas
No direct effect
Conversion of liver glycogen to glucose
No direct effect
Muscles of the uterus
Blood vessels of external genitalia
No direct effect
Secretion of sweat
No direct effect
No direct effect
Secretion of epinephrine and norepinephrine
No direct effect
1. Research a neurological article investigating pathologic changes that affect motor control and those that affect the sensory pathways. Write a one-page paper summarizing your reading.
E- OUTPUT ARTICLE SUMMARY
Parkinson's disease, a degenerative disorder of the CNS, is usually manifested by an impairment of (mostly) motor skills, cognitive processes and other brain functions. This is a disease which usually occurs with older aged people, but recent studies show that it may also appear at a younger age.
The etiology of Parkinson's Disease (PD) is usually genetic, or may be at times idiopathic. PD is known for its symptoms and is always present during diagnosis: tremor, rigidity, bradykinesia or akinesia, and postural instability, all of which are motor impairments. It may also show non-motor impairments such as impairment of cognitive and behavior functions, and sleep and sensory functions.
The mechanism of disease is mainly by prevention of forming or action of dopamines, which is manufactured in the substantia nigra. Dopamine is a catecholamine neurotransmitter in the brain which is very vital for movement and cognition. Prevention of dopamine secreting cells in the pars compacta of the substantia nigra, is caused by abnormal accumulation of protein alpha-synuclein which forms "Lewy bodies", a clinical hallmark in PD.
Numerous studies have been made on the other mechanisms that may cause the dopamine neurons to die, or the degeneration of brain cells itself in Parkinson's disease. In one study, researchers have studied the relation of the parkin gene (responsible for mediation of protein degradation) and endophilin-A (binding protein responsible for regulating formation and recycling of synaptic vesicles) during synaptic transmission. In PD, the parkin gene is mutated or is abnormal thereby when bounded to endophilin-A, it causes protein (endophilin-A) degradation and death of dopamine neurons. Death of these neurons is mainly caused by prevention of neurotransmitter uptake due to the absence or destruction of synaptic vessels that resulted from degradation of endophilin-A.
In another study, brain cell deaths in people with PD have been found to also be caused by brain cells being forcibly separated with its mitochondria, the power house of a cell. Brain cells need constant energy to function, therefore, when its cells' energy manufacturers itself are removed, it causes instant death to these cells. Researchers studied the cause of these "forced" separations and found that in PD, there are 10 gene sets that carry the same or common thread called PGC-1 alpha, the master regulator gene. This is a new target for pharmaceutical companies in order to halt or possibly stop brain cell death in PD.
All of these causes lead to the carrying out of the disease process, which has already been carefully studied and put into stages from where the accumulation and neurological affectation causing impairment starts, passes through, and where it eventually ends on. These stages are collectively called the Braak stages.
In stage I, the affected portions are the dorsal motor nucleus of the vagal nerve and the anterior olfactory structures. In this stage, called the mild or early disease, is manifested by symptoms that affect only one side of the body. Symptoms are usually inconvenient to the affected, but it is not disabling. Tremors of only one limb usually will happen, and changes in the person's posture, facial expression and locomotion will be evident.
In stage II, the affected portions are the lower raphe nuclei and locus coeruleus. Affected are both sides of the body, but the person's posture is still normal. He or she has minimal disability, and gait and posture are evidently affected.
In stage III, the affected portions are substantia nigra, amygdale and nucleus basilis of Meynert. This is the stage when clients with PD are usually diagnosed. Both sides of the body are again affected, and mild imbalance and impairment happens during walking or standing. Despite that, the client still is independent. The client has generalized moderately severe disability. Dyskinesias also occur in this stage. The cardinal signs explained earlier in this summary is evident in this stage.
In stage IV, the temporal mesocortex is affected. This is the advanced disease stage. Client's both sides of the body are greatly affected with accompaniment of disabling instability during walking or standing. Tremor may be less in this stage.
In stage V, the temporal neocortex, sensory association and premotor areas are affected. In this stage, the disease is fully developed and severe. He or she is already restricted to the bed or chair and motor and cognitive functions are greatly impaired.
In stage VI, the neocortex, primary sensory and motor areas are now affected, and is evidenced by further cognitive and motor impairment.