Located superior to each of the kidneys. It contains cells that on sympathetic stimulation secrete epinephrine and norepinephrine.
In mammals, the adrenal glands (also known as suprarenal glands) are the triangle-shaped endocrine glands that sit on top of the kidneys; their name indicates that position (ad-, "near" or "at" + -renes, "kidneys"). They are chiefly responsible for regulating the stress response through the synthesis of corticosteroids and catecholamines, including cortisol and adrenaline.
The adrenal gland has a distinct cortex and medulla, each of different embryologic origin and different function.
Axonal fibers that conduct impulses toward the central nervous system or nerve cell body.
Afferent is an anatomical term with the following meanings:1.Conveying towards a center, for example the afferent arterioles conveying blood towards the Bowman's capsule in the Kidney. 2.Something that so conducts.3.Afferent lymphatic vessels
Acquired impairment in recognizing objects while the primary modalities of sensation (touch, vision, hearing) are normally functioning.
Agnosia (a-gnosis, "non-knowledge", or loss of knowledge) is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss. It is usually associated with brain injuryor neurological illness, particularly after damage to the temporal lobe.
Agnosia can result from strokes, dementia, or other neurological disorders. It may also be trauma-induced by a head injury, brain infection, or hereditary. Some forms of agnosia have been found to be genetic.
Progressive cognitive (dementia) syndrome occurring after chronic HIV-1 encephalitis.
AIDS dementia complex (ADC; also known as HIV dementia, HIV encephalopathy and HIV-associated dementia) is a common neurological disorder associated with HIV infection and AIDS. It is a metabolic encephalopathy induced by HIV infection and fueled by immune activation of brain macrophages and microglia.
These cells are actively infected with HIV and secrete neurotoxins of both host and viral origin. The essential features of ADC are disabling cognitive impairment accompanied by motor dysfunction, speech problems and behavioral change. Cognitive impairment is characterised by mental slowness, trouble with memory and poor concentration. Motor symptoms include a loss of fine motor control leading to clumsiness, poor balance and tremors. Behavioral changes may include apathy, lethargy and diminished emotional responses and spontaneity. Histopathologically, it is identified by the infiltration of monocytes and macrophages into the central nervous system (CNS), gliosis, pallor of myelin sheaths, abnormalities of dendritic processes and neuronal apoptosis.
ADC typically occurs after years of HIV infection and is associated with low CD4+ T cell levels and high plasma viral loads. It is sometimes seen as the first sign of the onset of AIDS. Prevalence is between 10-20% in Western countriesand has only been seen in 1-2% of India based infections.
This has to due to with differences in diets, such as consumption of curcumin (in curry) and EGCG or Theaflavins (in teas), both which can pass the blood brain barrier and have neuroprotective effects. With the advent of highly active antiretroviral therapy (HAART), the frequency of ADC has declined in developed countries. HAART may not only prevent or delay the onset of ADC in people with HIV infection, it can also improve mental function in people who already have ADC.
Dementia only exists when neurocognitive impairment in the patient is severe enough to interfere markedly with day-to-day function. That is, the patient is typically unable to work and may not be able to take care of him or herself. Before this, the patient is said to have a mild neurocognitive disorder.
Slow initiation, or loss of power of voluntary movements seen in patients with basal ganglia pathology.
Akinesia(from the prefix a-, "without", and the Greek κίνηση, kinisi, "motion") is the inability to initiate movement due to difficulty selecting and/or activating motor programs in the central nervous system. Common in severe cases of Parkinson's disease, akinesia is a result of severely diminished dopaminergic cell activity in the direct pathway of movement.
State of altered consciousness in which the patient appears intermittently alert but is unresponsive despite intact motor skills.
Akinetic mutism is a condition in which a person is both mute and akinetic. A textbook on clinical neurology observes that a person with akinetic mutism has "sleep-waking cycles but, when apparently awake, with eyes open, lies mute, immobile and unresponsive." Some dictionaries describe it as "loss of normal muscle tone."
Alar plate zone of the embryonic neural tube dorsal to the sulcus limitans. Dorsal gray columns of the spinal cord and sensory centers of brain develop from this region.
The alar plate (or alar lamina) is a neural structure in the embryonic nervous system, part of the dorsal side of neural tube, that involves the communication of general somatic and general visceral sensory impulses. It later becomes a sensory region and part of the spinal cord.
One of the fetal membranes related to urinary bladder development. Not functionally important in human development.
Allantois (plural allantoides or allantoises) is a part of a developing animal conceptus (which consists of all embryonic and extra-embryonic tissues). It helps the embryo exchange gases and handle liquid waste.
The allontois, along with the amnion and chorion (other embryonic membranes), identify humans as amniotes, along with reptiles, dinosaurs, birds, and other mammals.
This sac-like structure is primarily involved in respiration and excretion, and is webbed with blood vessels.
The function of the allantois is to collect liquid waste from the embryo, as well as to exchange gases used by the embryo.
Largest and rapidly conducting spinal motor neuron , which controls the activity of skeletal muscle fibers.
Alpha motor neurons (α-MNs) are large lower motor neurons of the brainstem and spinal cord. They innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction. Alpha motor neurons are distinct from gamma motor neurons, which innervate intrafusal muscle fibers of muscle spindles.
While their cell bodies are found in the central nervous system (CNS), alpha motor neurons are also considered part of the somatic nervous system—a branch of the peripheral nervous system (PNS)—because their axons extend into the periphery to innervate skeletal muscles.
An alpha motor neuron and the muscle fibers it innervates is a motor unit. A motor neuron pool contains all the alpha motor neurons involved in contracting a single muscle.
Brain wave with a frequency between 8 and 13 HZ. Occurs when the patient is relaxed with the eyes closed.
Alpha waves are electromagnetic oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent (in phase / constructive) electrical activity of thalamic pacemaker cells in the human brain. They are also called Berger's wave in memory of the founder of EEG.
Alpha waves are one type of brain waves, commonly detected by electroencephalography (EEG) or magnetoencephalography (MEG) and predominantly found to originate from the occipital lobe during periods of relaxation, with eyes closed but still awake. Conversely alpha waves are attenuated with open eyes as well as by drowsiness and sleep. They are thought to represent the activity of the visual cortex in an idle state.
Brainstem lesion characterized by cranial nerve impairments on the side ipsilateral to the lesion and hemiplegia and sensory loss on the opposite side.
Alternating hemiplegia is a rare condition where a child has episodes of weakness affecting one side of the body. This weakness can affect all the muscles on the affected side, not just those in the limbs. After an episode, the weakness improves, but will recur during the next episode. Alternating hemiplegia is a variable condition that affects children to differing degrees and in a variety of ways. This can make it a difficult condition to diagnose and manage but much expertise has been gained in recent years.
Alternating hemiplegia is a condition which has transient weakness of either, or sometimes both, sides of the body. The attacks may alternate or sometimes overlap, that is the second side is affected before the first recovers. Attacks start in the first year of life and are often accompanied by unusual irregular eye movements. The attacks last from less than an hour which is unusual to sometimes several days. When the attacks are prolonged the manifestations are not apparent during sleep or for the first fifteen to twenty minutes on waking when they then return. This is a very characteristic finding and when there are bilateral attacks this may allow feeding and drinking to occur in that short clear period after waking. The episodes of hemiplegia are not epileptic in nature but epileptic seizures may co-exist and require separate anti-epileptic drug treatment.
The cause is not known. Affected children usually have significant learning disabilities and motor organisational problems, including unsteadiness. There is a tendency for these problems to increase with repeated episodes.
Treatment is with flunarizine (a calcium channel blocker). Other drugs have not been found to be consistently helpful.