CBSE Class 12 Biology Chapter 8 Revision Notes Part 2

Chapter 8: Human Health and Diseases Revision Notes Part 2

Multiple Choice Questions

Which type of tumors can invade adjacent tissues and cause harm? _______
Plasmodium, the parasite that causes malaria, is spread from person to person by the bite of the female Anopheles mosquito. __________
The HIV virus uses __________ to generate viral DNA in the host.
Which of these impacts the cardiovascular system? ___________
Ringworm is caused by _________.

A state of complete physical, mental, and social well-being is characterized as health.
A pathogen is a disease-causing organism, such as bacteria, viruses, protozoans, fungus, or worms.
A pathogen can enter our bodies in a variety of ways.

Typhoid: caused by a bacteria, Salmonella typhi.

One can contract this disease through contaminated food and water.
Symptoms include high fever, headache, constipation, and loss of appetite.
This disease can be diagnosed by performing a Widal test, and intestinal perforations can be seen In some extreme cases.

Pneumonia: a lung infection that causes the air sacs in one or both lungs to become inflamed.

Cough with phlegm or pus, fever, chills, and trouble breathing can occur when the air sacs fill with fluid or pus (purulent material).
Streptococcus pneumoniae is the most prevalent cause of bacterial pneumonia.
This form of pneumonia can develop independently or as a result of a cold or virus.

Ascariasis: a parasitic illness of the small intestine.

Caused by the roundworm Ascaris lumbricoides.
Roundworms are parasitic worms, and Roundworm infections are rather frequent.
The most prevalent roundworm infection is ascariasis.

Ringworm: A fungus causes ringworm, which is a common skin illness.

Because it can create a circular rash (formed like a ring) that is generally red and itchy, it’s nicknamed “ringworm.”
Ringworms may affect anyone.

Malaria: Malaria is an infectious illness spread by mosquitoes that affect people and other animals.

Malaria is characterized by fever, exhaustion, vomiting, and headaches.
In extreme cases, it can cause yellow skin, convulsions, coma in extreme cases, or death.
Lifecycle of Plasmodium
- Plasmodium is spread from person to person by female Anopheles mosquito bites.
- Sporozoites, which are formed by female anopheles saliva after they bite, are the infectious form.
- Before attacking RBCs, it replicates in liver cells, leading RBCs to explode.
- Haemozoin, a harmful toxin, is secreted.
- The infected person’s gametocyte is transferred to the mosquito whenever a mosquito bites an infected person.
- Macro and micro gametocytes get fertilized, converted, and sporogenesis happens in the mosquito’s stomach, culminating in the formation of sporozoites.
- The cycle is restarted when sporozoites reach a mosquito’s salivary gland.
- Plasmodium sp. needs both humans and female Anopheles mosquitoes to finish its life cycle.

Plasmodium lifecycle

Caused by HIV (Human Immunodeficiency Virus)
The virus uses the reverse transcriptase enzyme to generate viral DNA in the host.
The viral DNA is integrated into the host genome, resulting in numerous copies of the virus.
The virus targets helper T-cells, where it replicates and multiplies, resulting in a significant reduction in T lymphocyte numbers.
After the virus targets T-helper cells, the infected person develops immunodeficiency.
AIDS patients are vulnerable to infections such as mycobacterium, toxoplasma, fungal, and viral infections.
The ELISA test is a commonly used AIDS diagnostic test.
AIDS can be passed down from mother to fetus through the placenta, contaminated blood transfusions, or using an infected syringe.

HIV Replication Cycle

Source: HIV

Cancer is caused by unregulated cell division, which results in tumor development.

Tumors

Cancerous cells cannot stop future cell proliferation when they touch other cells.
Non-invading benign tumors stay in their original position and do not spread.
Malignant tumors can invade adjacent tissues and cause harm.
Metastasis is a feature of malignant tumors in which sloughed-off cells travel to distant areas and establish tumors in various sections of the body.
Cancer is caused by DNA damage or genetic mutations that result in improper cell cycle control.
Under some conditions, cancer can also be triggered by the activation of proto-oncogenes found in normal cells.
Ionizing radiation (e.g., X-rays, gamma rays), non-ionizing radiation (UV rays), chemical agents (e.g., tobacco), viral oncogenes of oncogenic viruses are all examples of carcinogens.
A CT scan, MRI, X-ray, PET scan, or histological investigations of tissue and blood can all be used to identify cancer.
Molecular biology approaches can also diagnose cancer by identifying inherited cancer-prone genes.
Surgery, transplantation, immunotherapy, and radiation therapy are all options for cancer treatment.
𝛂 -interferon acts as a biological response modifier, activating the immune system and causing it to attack the tumor.

Commonly misused drugs include opioids, cannabinoids, and coca alkaloids.

Opioids bind to opioid receptors in our central nervous system and gastrointestinal tract.
Diacetylmorphine is sometimes known as smack or heroin.
It’s made from the latex of the Papaver somniferum poppy plant, and the acetylation of morphine produces it.
Cannabinoids interact with the brain’s cannabinoid receptors, and they have an impact on the cardiovascular system.
Cannabis, hashish, charas, ganja, and other cannabinoids are extracted from the plant’s flower tops, leaves, and resins, Cannabis sativa.
Cocaine, also known as coca alkaloid, is derived from the Erythroxylum coca plant.
Cocaine works by interfering with dopamine transport, a neurotransmitter.
Cannabinoids are also used by athletes to improve their performance, muscle relaxation, and anxiety reduction.
Morphine is a sedative and a pain reliever.
Depression, sleeplessness, and other mental illnesses are treated with barbiturates, amphetamines, and benzodiazepines, among other drugs.
Tobacco’s nicotine (alkaloid) promotes the adrenal gland’s secretion of adrenalin and nor-adrenalin hormones. It raises blood pressure and heart rate.
Smoking causes oxygen deficit by raising carbon monoxide levels in the blood, lowering the concentration of oxygen bound to hemoglobin.
Excessive drug and alcohol use harms the nervous system and leads to liver cirrhosis.