Class 22 Cardiovascular System and Infections

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Questions and Answers

What is the role of iron sequestration by pathogens within macrophages?

It promotes cytokine production.

It prevents the growth of macrophages.

It enhances cellular respiration.

It is needed for the pathogens to grow. (correct)

What leads to the formation of buboes in the early stages of a disease caused by certain pathogens?

Improper immune response.

Direct tissue damage from toxins.

Inflammation of lymph nodes. (correct)

Spread of toxins through the bloodstream.

What is a significant consequence of necrosis in lymph nodes for septicemic plague cases?

Enhanced local immune response.

Entry of pathogens into the bloodstream. (correct)

Death of surrounding epithelial cells.

Increased cytokine production.

What is the main mode of transmission for Borrelia burgdorferi?

Feeding stages of infected ticks. Signup and view all the answers

Which of the following is a characteristic symptom of the disease caused by Borrelia burgdorferi?

Bull's eye rash. Signup and view all the answers

What is the primary recommended treatment for infections caused by Yersinia pestis?

Antibiotics administered promptly. Signup and view all the answers

Where is Yersinia pestis endemic?

Africa, Asia, South America, and parts of the United States. Signup and view all the answers

What is a potential complication in untreated pneumonic plague cases?

Coughing up blood. Signup and view all the answers

What is the first location that a sporozoite travels to after being injected into the human bloodstream by a mosquito?

Liver Signup and view all the answers

How long does a sporozoite remain in the bloodstream before it disappears?

30 minutes Signup and view all the answers

What does a sporozoite transform into after entering liver cells?

Trophozoite Signup and view all the answers

What is the primary role of infected dendritic cells during a viral infection?

To take antigens to lymph nodes Signup and view all the answers

What immediate action occurs when infected red blood cells rupture?

Release of merozoites Signup and view all the answers

What condition can result from a severe response of the immune system to a second infection with a different strain of dengue?

Bone break fever Signup and view all the answers

What triggers the body's systemic inflammation during an infection?

Lysed red cells and parasite debris Signup and view all the answers

Which statement correctly describes the effect of antibodies in the case of a secondary dengue infection?

Antibodies can bind but not inactivate the virus. Signup and view all the answers

How quickly do merozoites invade new red blood cells after escaping from the ruptured cells?

10 minutes Signup and view all the answers

What is one of the historical impacts of yellow fever in the United States?

Impeded the building of the Panama Canal Signup and view all the answers

What is a significant characteristic of red blood cells regarding their nutritional content for parasites?

Limited diet of hemoglobin Signup and view all the answers

What is a characteristic symptom of yellow fever related to liver function?

Decreased liver function leading to jaundice Signup and view all the answers

Why is vaccination against dengue only recommended for individuals who have been previously infected?

Vaccination may worsen the infection in naive individuals. Signup and view all the answers

What happens to the liver cells infected by sporozoites during the lifecycle?

They rupture to release merozoites Signup and view all the answers

What is a main method of transmission for both Dengue and Yellow Fever viruses?

Mosquito bites Signup and view all the answers

What complication can arise from the immune system's cytokine storm during severe dengue infection?

Severe pain in joints and muscles Signup and view all the answers

Why did slaves from Africa not suffer from yellow fever and malaria as much as indentured servants?

They had previous exposure and developed immunity. Signup and view all the answers

What is the primary infectious agent responsible for malaria?

Plasmodium sp. Signup and view all the answers

What are the two most common species of Plasmodium that cause malaria in humans?

Plasmodium vivax and Plasmodium falciparum Signup and view all the answers

What characteristic of malaria symptoms is described in the content?

Fever that alternates with chills and sweating Signup and view all the answers

Which type of mosquito is exclusively required for human malarias?

Anopheles mosquitoes Signup and view all the answers

How can malaria occur outside of tropical regions?

Through a special strain that remains dormant. Signup and view all the answers

How was malaria eliminated in areas where it was once endemic?

By controlling and eliminating the mosquito vector. Signup and view all the answers

What is indicated by the term 'Ague' in relation to malaria symptoms?

A period of extreme shivering and cold. Signup and view all the answers

What must occur after a human is bitten by an infected anopheles mosquito for the malaria cycle to continue?

The mosquito must survive for at least two weeks. Signup and view all the answers

Which mutation is highlighted as a notable genetic adaptation against malaria?

Sickle Cell Signup and view all the answers

What happens to hemoglobin in red blood cells of individuals with homozygous sickle cell trait at low oxygen levels?

It crystallizes and distorts the red blood cells. Signup and view all the answers

What is the outcome for children who are homozygous for sickle Hb without medical intervention?

They will die. Signup and view all the answers

How does being heterozygous for sickle cell trait affect an individual's health in relation to malaria?

It offers some degree of protection against malaria. Signup and view all the answers

Why might the prevalence of sickle cell trait persist in malaria-prone regions?

It provides reproductive advantages to carriers. Signup and view all the answers

In the genetic cross of two parents with sickle cell traits, what percentage of children will likely die if both parents are carriers?

25% Signup and view all the answers

What is the significance of the mutation in hemoglobin related to its hydrophobicity?

It increases the tendency for hemoglobin to crystallize. Signup and view all the answers

What is the consequence of red blood cells rupturing simultaneously in infected individuals?

Activation of macrophages targeting debris Signup and view all the answers

What is a unique characteristic of P.vivax that affects its life cycle?

It can lie dormant in the liver and cause relapsing malaria. Signup and view all the answers

How does P.falciparum infect the body during its lifecycle in red blood cells?

By creating sticky knobs that bind to capillary walls Signup and view all the answers

What is one serious complication associated with P.falciparum infection?

Localized inflammation and damage to the fetus Signup and view all the answers

What process occurs in the Anopheles mosquito after infected red blood cells undergo fertilization?

Zygotes develop and move to the salivary glands Signup and view all the answers

What signals the gametes to emerge from infected red blood cells in the mosquito?

A change in environmental temperature Signup and view all the answers

Where do sporozoites travel after being released in the mosquito's stomach?

To the salivary glands for transmission Signup and view all the answers

What are the primary targets of P.falciparum in the human body?

Brain capillaries and placenta Signup and view all the answers

Study Notes

Cardiovascular System

Circulates blood and lymph fluids
Normally sterile (free of microorganisms)
Infections can become systemic
Worst cases include cytokine storms, sepsis, and life-threatening tissue damage
Blood and lymph are immune defense sites

Key Organs

Lymph nodes: Concentrates immune cells to test for invaders
Spleen: Removes debris from blood (using many macrophages) and acts as a lymph node for blood
Liver: Detoxifies blood and acts as a lymph node for blood

How Infections Reach the Blood System

Breaches of mucosal membranes (e.g., TB, UTI, STI, wounds)
Medical device transmission (e.g., shared needles)
Accidental infections
Infections that require systemic spread through blood/lymph to complete their cycle
Infections need regular access to blood/lymph and a plan to reach other hosts
These are viral, bacterial, and parasitic infections

Special Group - Blood-Sucking Arthropods

Injected into blood or lymph; built-in ways to re-infect
Zoonotic infections (carried by animals transmitted to humans by bites)
Others can survive in the host and transmit from person to person
Have a close relationship with both the arthropod (vector) and human (host).
Example: Fleas are ectoparasites, living on animals and regularly consuming blood. Different fleas have preferences (e.g., cat fleas, dog fleas, and others)

Rat Fleas and the Black Death

Plague is a disease transmitted by the rat flea and Yersinia pestis
Affects rodents and humans
Plague spreads through rat populations and fleas
Causes fleas to carry whatever they can get from dead rats to infect new hosts

Pathogenesis

Proteases break down fibrin clots
Multiplies within macrophages (need iron)
Injects toxins into cells to disrupt cytoskeleton and prevent phagosome development
Blocks cytokine production
Necrosis in lymph nodes leads to septicemia and shock

Disease Progression

Regurgitation and scratching from bite wound spreads to lymph nodes
Enlarged and tender lymph nodes (called buboes)
Infection spreads to blood stream
Can cause systemic infection, high fever, and diffuse bleeding into skin.
Can infect lungs and cause a potentially fatal form of pneumonic plague (spread through aerosols) – no longer requires fleas

Treatment

Antibiotics immediately
Prevention via rodent control and flea insecticides
No widely effective vaccine, but research is underway

Endemic Areas

Africa, Asia, South America, and some areas in the western United States (ground squirrel populations)

Ticks

Borrelia burgdorferi (Gram-negative, microaerophilic spirochete)
Tick-borne infections (commonly infect animals, but humans are incidental hosts)
Transmission occurs through tick bites, with infection lasting the life of the tick
Incubation periods are relatively long
Symptoms start with a localized infection with inflammation that spreads outward as an erythema migrans rash (bull's-eye)
May cause flu-like symptoms and local lymph node swelling

Disseminated Disease (Long-Term)

Symptoms appearing with a delay up to 2-10 weeks of initial infection
Symptoms include dizziness, fainting, facial paralysis, headache, stiff neck, difficulty concentrating, and cardiovascular complications
Can last up to 6+ months, with joint pain and arthritis being common
Treatable if caught early, but often goes unnoticed

Mosquitoes

Primarily feed on nectar but need protein when reproducing
Can transmit diseases like dengue and malaria

Dengue

Enveloped, single-stranded RNA virus
Transmitted by Aedes mosquitoes (like Aedes aegypti and A. albopictus)
Infect humans and other mammals, but not all species
Common in urban areas where recycled materials and water collecting can lead to breeding
Virus multiplies in macrophages and dendritic cells, spreading through blood to infect more cells and tissues.
Can result in fever, rash, joint and muscle pain, and, in severe cases, hemorrhaging and organ dysfunction.
Can cause several complications

Reinfection

Reinfection from a different strain can result in a more severe illness than initial infection

Yellow Fever

Enveloped, single-stranded RNA virus
Transmitted by Aedes mosquitoes
Causes liver infection, resulting in jaundice
Severe symptoms with high potential for fatality rates

Malaria

Infect humans and other animals via mosquito bites
Four varieties are common, including P. vivax and P. falciparum
Humans are an incidental host, needing very specific types of mosquitoes.

Malaria Life Cycle

Mosquito injects sporozoites into blood, traveling to liver
Sporozoites transform into trophozoites and then schizonts. These develop into thousands of merozoites that invade red blood cells
Host red blood cells rupture, unleashing merozoites that then attack further red blood cells, causing symptoms (every 48-72 hours)
Other stages in mosquito
Cycle repeats until controlled

Other Notes

P. vivax can undergo a dormant phase in the liver
P. falciparum produces sticky knobs that let them take root in blood vessels
Malaria causes a cyclical pattern of fever, chills, sweats, weakness, and other symptoms as the red blood cells rupture.
Treatment generally is antibiotics. There are vaccines for some of these diseases.

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Description

Explore the essential functions of the cardiovascular system and its role in immune defense. This quiz covers key organs, pathways for infections to enter the bloodstream, and the implications of blood-sucking arthropods. Test your knowledge of how infections can become systemic and affect overall health.