Introduction to Plasmodium

Plasmodium is an intracellular protozoan parasite. It is also a digenetic parasite i.e it needs two host for completion of lifecycle one is human and the other is female anopheles mosquito.

Summary

Plasmodium is an intracellular protozoan parasite. It is also a digenetic parasite i.e it needs two host for completion of lifecycle one is human and the other is female anopheles mosquito.

Things to Remember

  •  It is a digenetic parasite i.e it needs two host for completion of lifecycle one is human and the other is female anopheles mosquito.
  • Only 4 species of Plasmodium are infective to man which causes malaria.
  • Plasmodium falciparum is the most dangerous species which causes cerebral malaria and black water fever.
  • In Nepal, it is common in terai region. 10 districts of hilly region are reported as malaria free district.

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Subjective Questions

Q1:

Define electroencephalogram. What is the device that is used to record this signal?


Type: Short Difficulty: Easy

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Answer: <p>The recorded graphical representation of bio-electric potentials generated due to neuronal activity of the brain is called electroencephalogram (EEG). The device used to record these electrical activities of the brain is called electroencephalograph.</p>

Q2:

What do you mean by evoked potential? Which evoked potentials are most frequently encountered?


Type: Short Difficulty: Easy

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Answer: <p>If the sensory area of the brain is stimulated, it responds by generating a low amplitude of action potential known as Evoked Potential (EP). Evoked potential helps to test and record how quickly and completely the nerve signals reach the brain. EP is used because it can indicate problems along nerve pathways that are too subtle to show up during a neurologic examination or to be noticed by the patient. The disruption may not be visible even in MRI. It is helpful in making the diagnosis of multiple sclerosis (MS) and other neurological disorders. The EP's most frequently encountered are :</p> <ul><li>Visual evoked potential(VEP)</li> <li>Short-latency somatosensory evoked potential (SEP)</li> <li>Short-latency brainstem auditory evoked potential (BAEP)</li> </ul>

Q3:

What are different types of electrodes used for recording of EEG?


Type: Long Difficulty: Easy

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Answer: <p>There are different types of electrodes used for the recording of EEG signals.Electrodes that make the best contact with a subject's scalp and contain materials that most readily detect EEG signals provide the best EEG recordings. Some of the electrodes used are as follows:</p> <ul><li>Reusable disks:These can be placed close to the scalp, even the region with hair. They are very small and small amount of conducting gel is used under each disks. They are made up of stainless steel, tin, gold or silver. They can be cleaned with soap and water or Cidex. Their cost depemds upon the type of material they are made up of.</li> <li>EEG caps with disks<strong>:</strong>There are different types of caps available with different number and types of electrodes. Some are available for using with reusable disks and leads. Gel is injected under each disk through a hole in the back of the disk. The disc on the region of the scalp with hair cannot be placed as close to the scalp as individual electrodes, so a greater amount of gel needs to be injected under each disk. Their cost can be moderate to high depending upon the longetivity and style of cap and electrodes.</li> <li>Adhesive Gel Electrodes:They act as a malleable extension of the electrodes, so that the movement of electrode cable is less likely to produce artifacts. The gel maximizes the skin contact and allows for a low-resistance recording through the skin.</li> </ul><p></p>

Q4:

Explain \(\frac{10}{20}\) system of EEG recording?


Type: Short Difficulty: Easy

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Answer: <p>The amplitude, phase and frequency of EEG signals highly depend upon the electrode placement. This placement is based upon the frontal, parietal, temporal and occipital cranial area. The internationally standarized \(\frac{10}{20}\) system is the most widely used system for EEG electrode configuration. In this system 21 electrodes are located on the surface of the scalp. The head is mapped by four standard points: the nasion,the inions, the left earand right ear. The positions are determined as :</p> <p></p> <figure class="" style="width: 200px;"><img src="/uploads/10-20_system_for_EEG2.png" alt="Fig: Electrodes placement for 10/20 system" width="200" height="179"><figcaption>Fig: Electrodes placement for 10/20 system</figcaption></figure><ul><li>Reference points are nasion, which is the delve at the top of the nose, level with the eyes.</li> <li>Inions, which is bony lump at the base of the skull on the midline at the back of the head.</li> </ul><p>From these points, the skull perimeters are measured in the transverse and median planes. Electrode locations are determined by dividing these perimeters into 10% and 20% intervals.</p>

Q5:

What do you mean by bipolar and monopolar recording technique? Show with diagram.


Type: Short Difficulty: Easy

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Answer: <p>The amplifiers are connected between the pairs of scalp electrodes in a regular orderand voltage difference between the two scalp electrodes is recorded in bipolar recording.</p> <p></p> <figure class="" style="width: 200px;"><img src="/uploads/bp3.jpg" alt="Fig: Biopolar recording technique" width="200" height="112"><figcaption>Fig: Biopolar recording technique</figcaption></figure><p></p> <p>In monopolar recording the amplifiers are connected between the scalp electrodes and a reference electrodes and the voltage difference between respective scalp electrode and reference electrode is recorded.</p> <figure class="" style="width: 200px;"><img src="/uploads/mono4.jpg" alt="Fig: Monopolar recording technique" width="200" height="138"><figcaption>Fig: Monopolar recording technique</figcaption></figure>

Q6:

List different wave-bands along with their frequencies during EEG recording technique.


Type: Short Difficulty: Easy

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Answer: <p>The list of different wave-bands along with their frequencies are as follows:</p> <table width="591"><tbody><tr><td> <p>Wave Band </p> </td> <td> <p>Frequency(Hz) </p> </td> <td> <p>Condition</p> </td> </tr><tr><td> <p>&alpha;-Rhythm</p> </td> <td> <p>8-13 Hz</p> </td> <td> <p>Parietal-occipital; seen best when both eyes closed or in relaxed condition.&alpha;- Rhythm is most prominent when anesthesia is given. It also serves as indicator of anesthetic during surgery.</p> </td> </tr><tr><td> <p>&beta;- Rhythm</p> </td> <td> <p>13-22 Hz</p> </td> <td> <p>Frontal-Parietal; seen best when&alpha; is blocked or a person becomes fully alert.</p> </td> </tr><tr><td> <p>&delta;- Rhythm </p> </td> <td> <p>0.5-4 Hz</p> </td> <td> <p>Associated with normal sleep; present in children less than a year.</p> </td> </tr><tr><td> <p>&theta;- Rhythm</p> </td> <td> <p>4-8 Hz</p> </td> <td> <p>Present in children above 1 year old.</p> </td> </tr></tbody></table>

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Introduction to Plasmodium

Introduction to Plasmodium

It is an intracellular protozoan parasite. It is also a digenetic parasite i.e. it needs two hosts for completion of lifecycle one is human and the other is female anopheles mosquito. Female anopheles mosquito also acts as a vector ( an insect which transmits causative agent from one person to another). Only 4 species of Plasmodium are infective to man which causes malaria.

P.vivax → BenginTertian Malaria

P. falciparum → Malignant Tertian Malaria

P. malaria → Quartan Malaria

P. ovale → Mild Tertian Malaria

Plasmodium falciparum is the most dangerous species. It cause cerebral malaria and black water fever.


source:www.biologydiscussion.com trophozoit of plasmodium
source:www.biologydiscussion.com
fig:trophozoites of plasmodium

Plasmodium vivax

Classification:

kingdom: Protista

Phylum : Protozoa

Class : Sporozoa

Genus : Plasmodium

Species : Vivax

Common name : Malarial parasite


source:www.biologydiscussion.com A sporozoite of plasmodium
source:www.biologydiscussion.com
fig:A sporozoite of plasmodium

Habit, Habitat, and Distribution

  • It is an intracellular protozoan parasite.
  • It lives inside RBC and liver cell of the human host, stomach and salivary gland of mosquito host.
  • It is worldwide in distribution.
  • It is the most common species mainly found in hot tropical and temperate region of the world.

In Nepal, it is common in terai region. 10 districts of the hilly region are reported as malaria free district.

Structure of Plasmodium:

It mostly occurs in two different morphological stages:

  • Trophozoite
  • Sporozoite

Trophozoite Sporozoite
It is a fully grown feeding stage of plasmodium. It is a non-infecting stage of plasmodium.
It is formed in human RBC. It is formed in salivary glands of mosquito.
It is in rounded or amoeboid shape. It is in sickle- shaped.
Nucleus is eccentric. Nucleus is present in the centre.
The body is covered with plasmalemma. Body is covered with the pellicle.
It is non- motile. It is motile.
Food vacuole contains toxic haemozoin pigment. Food vacuole contains apical cap and secretory glands for penetration of the host cell.

Incubation period:

It is the period between initial infection of sporozoites and appearance of the first symtom. It is of 14 days in P.vivax.

Paroxysm:

The rise of malarial fever at the interval of every 48 hours is called paroxysm. Such fever is also called intermittent or relapsing fever.

Relapse:

It is the reoccurrence of malarial symptoms after the certain time period of treatment. It is caused by crypto merozoites of the previous infection as they are unaffected by anti-malarial drugs.

Lesson

Plasmodium

Subject

Biology

Grade

Grade 11

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