Tag: community health and hygiene

A refractory period is a period of time during which an organ or cell is incapable of repeating a particular action. 

Berger waves, also called as $\alpha$-waves are neural oscillations in the frequency range of 7.5-12.5 Hz. $\alpha$-waves are called as Berger waves in the memory of the founder of EEG.
$\alpha$-waves are one type of brain waves detected either by either EEG, electroenccephalography or magnetoencephalography (MEG) and predominantly originate form the occipital lobe during wakeful relaxation with closed eyes.
Thus, the correct answer is option (C), 'Brain'.

Magnetoencephalography or MEG is a non-invasive technique for investigating human brain activity. It allows the measurement of the ongoing brain activity on a millisecond-by-millisecond basis and it shows where in the brain activity is produced. So, it is helpful in shocked patients.
So, the correct answer is option C.

The tenth cranial nerve (X) is the vagus nerve. It is the longest cranial nerve. (Its name means "wanderer"). It supplies most of the organs in the thoracic and abdominal cavities. This nerve also contains motor fibers to the larynx (voice box) and pharynx, and to glands that produce digestive juices and other secretions. The vagus nerve is responsible for such varied tasks as heart rate, gastrointestinal peristalsis, sweating, and quite a few muscle movements in the mouth, including speech. Parasympathetic innervation of the heart is partially controlled by the vagus nerve and is shared by the thoracic ganglia. To be specific, vagal and spinal ganglionic nerves mediate the lowering of the heart rate. 

Heart beat is initiated by the nodal cells of the SA node. It starts the heart beat. The electrical impulse is then carried by the nerves to the AV node and the Purkinje fibres. Thus the nerves help to spread the impulse throughout the heart. Hence the rate and rhythm of heart beat is controlled by the impulses travelling through the nerves.

The cardiac activity is controlled by the sympathetic nervous system through the epinephrine. It fastens the heartbeat and the cardiac output so that more concentration of oxygen can be supplied to the body parts.

The calcium ions are responsible for muscle contraction by generating the action potential in the muscle cells. More influx of calcium ions may contract the heart muscle to a prolonged state of contraction, which will lead to abnormal increase in the heart rate. 

An electroencephalogram (EEG) is a test that measures and records the electrical activity of your brain by using sensors (electrodes). EEG is most often used to diagnose epilepsy, which causes abnormalities in EEG readings. It is also used to diagnose sleep disorders, coma, encephalopathies, and brain death. EEG used to be a first line method of diagnosis for tumors, stroke and other focal brain disorders.

Magnetoencephalography (MEG) is a non-invasive neurophysiological technique that measures the magnetic fields generated by neuronal activity of the brain. The spatial distributions of the magnetic fields are analyzed to localize the sources of the activity within the brain, and the locations of the sources are superimposed on anatomical images, such as MRI, to provide information about both the structure and function of the brain. 

Electroencephalography (EEG) is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. German physiologist and psychiatrist Hans Berger recorded the first human EEG in 1924.