Growth Adaptations and Cell Injury

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Questions and Answers

What role does MPO deficiency play in infection susceptibility?

MPO deficiency increases the risk of Candida infections.

How do neutrophils differ from macrophages in terms of lifespan during inflammation?

Neutrophils undergo apoptosis within 24 hours, while macrophages peak at 2-3 days and continue to play a role in inflammation.

What are the two main signals required for T cell activation?

T cell activation requires the binding of the antigen/MHC complex and an additional second signal, often provided by a costimulatory interaction.

What is the defining feature of granulomatous inflammation?

The defining feature of granulomatous inflammation is the presence of epithelioid histiocytes. Signup and view all the answers

Which cytokines are mainly secreted by Th1 cells and what are their functions?

Th1 cells secrete IL-2 and IFN-gamma, where IL-2 promotes CD8 T cell activation and IFN-gamma activates macrophages. Signup and view all the answers

How does the process of B cell activation depend on T cells?

B cell activation depends on T cells through antigen presentation to CD4+ T cells, which provide a second activation signal via CD40L. Signup and view all the answers

Explain the importance of the NADPH oxidase in bacterial killing.

NADPH oxidase is crucial for generating reactive oxygen species, enabling effective bacterial killing; its defect results in impaired immune response. Signup and view all the answers

What characterizes the difference between MHC I and MHC II in relation to T cell subsets?

MHC I presents intracellular antigens to CD8+ T cells, while MHC II presents extracellular antigens to CD4+ T cells. Signup and view all the answers

What is the primary function of negative selection in the thymus?

To eliminate T cells that strongly bind to self-antigens, thereby preventing autoimmunity. Signup and view all the answers

How does the cytotoxic CD8+ T cell pathway induce cell death?

It uses perforins to create pores in the target cell membrane and granszyme enters these pores to activate caspases, leading to apoptosis. Signup and view all the answers

Which reactive oxygen species is considered the most damaging and why?

The hydroxyl radical (OH) is the most damaging due to its high reactivity with biological macromolecules. Signup and view all the answers

What is a common consequence of carbon tetrachloride (CCl4) exposure in the liver?

CCl4 exposure can cause cellular swelling and reversible injury, leading to fatty change due to impaired lipid metabolism. Signup and view all the answers

What are the main components of acute inflammation?

The main components are edema (fluid accumulation) and the influx of neutrophils into the affected tissue. Signup and view all the answers

What triggers fever during acute inflammation?

Fever is triggered by macrophages releasing IL-1 and TNF, which increase PGE2 levels in the hypothalamus to raise the body's temperature setpoint. Signup and view all the answers

What role do Toll-like receptors (TLRs) play in the immune response?

TLRs recognize pathogen-associated molecular patterns (PAMPs) and activate NF-kB, leading to an enhanced immune response. Signup and view all the answers

Describe the appearance of amyloid deposits in tissue.

Amyloid deposits display a beta-pleated sheet configuration and can be identified using Congo red staining, which shows apple-green birefringence under polarized light. Signup and view all the answers

What are the two main types of systemic amyloidosis and their causes?

Primary amyloidosis (AL) is due to Ig light chains, while secondary amyloidosis (AA) arises from serum amyloid A protein during chronic inflammation. Signup and view all the answers

What clinical condition is most commonly associated with kidney involvement in amyloidosis?

Nephrotic syndrome is the most common clinical condition associated with kidney involvement in amyloidosis. Signup and view all the answers

What distinguishes noncaseating granulomas from caseating granulomas?

Noncaseating granulomas lack central necrosis, while caseating granulomas contain central necrosis, commonly seen in tuberculosis and certain fungal infections. Signup and view all the answers

Describe the role of CD4 T cells in granuloma formation.

CD4 T cells are activated by IL-12 and release IFN-gamma, which converts macrophages into epithelioid histiocytes and giant cells, essential for granuloma formation. Signup and view all the answers

What is DiGeorge Syndrome and its genetic basis?

DiGeorge Syndrome is caused by a 22q11 microdeletion leading to the absence of the thymus and subsequent T cell deficiency, characterized by the acronym CATCH-22. Signup and view all the answers

What is the main defect in X-linked agammaglobulinemia?

The main defect in X-linked agammaglobulinemia is a mutation in Bruton tyrosine kinase, resulting in a complete lack of immunoglobulin due to disordered B-cell maturation. Signup and view all the answers

Explain the concept of central tolerance in the bone marrow.

Central tolerance in the bone marrow involves negative selection of immature B cells that strongly bind to self-antigens, leading to apoptosis or light chain editing. Signup and view all the answers

What are the two main causes of hyper-IgM syndrome?

Hyper-IgM syndrome is primarily caused by mutations in CD40L or CD40 receptor, leading to defects in T cell activation during B cell class switching. Signup and view all the answers

What is the significance of regulatory T cells in immune tolerance?

Regulatory T cells (CD4+ CD25+ FoxP3+) suppress immune responses and help maintain tolerance by blocking T cell activation and producing inhibitory cytokines. Signup and view all the answers

How does zinc deficiency affect wound healing?

Zinc deficiency impairs collagenase activity, which is vital for converting type III collagen to type I collagen during wound healing. Signup and view all the answers

What is apoptosis, and how is it regulated at the molecular level?

Apoptosis is a programmed cell death process regulated by the Bcl-2 family of proteins, which stabilize the mitochondrial membrane and prevent cytochrome c release. Signup and view all the answers

Describe how cancer cells invade surrounding tissues.

Cancer cells invade tissues by downregulating e-cadherin to detach from neighboring cells, binding to basal membrane components, and producing enzymes like collagenase IV to degrade the extracellular matrix. Signup and view all the answers

What is the relationship between immunodeficiency and cancer risk?

Immunodeficiency increases cancer risk due to inadequate immune surveillance, which reduces the body's ability to identify and destroy tumor cells. Signup and view all the answers

What role does IFN-gamma play in macrophage activation?

IFN-gamma released by activated CD4 T cells converts macrophages into a more effective form known as epithelioid histiocytes, enhancing their ability to engulf and destroy pathogens. Signup and view all the answers

Which cytokines are produced by regulatory T cells and what is their function?

Regulatory T cells produce cytokines such as IL-10 and TGF-beta, which inhibit T cell activation and promote immune tolerance. Signup and view all the answers

Study Notes

Growth Adaptations, Cell Death, and Injury

Atrophy is a decrease in cell size or number (apoptosis). It occurs through ubiquitin-proteosome degradation of the cytoskeleton and autophagy of cellular components.
Autophagy is a cellular process where vacuoles are formed to contain cellular components and then consumed by lysosomes.
Metaplasia is a reversible reprogramming of stem cells. It can occur with removal of the stressor that caused it, but can progress to cancer. An example of an exception is apocrine metaplasia, which is not linked to cancer. Vit A deficiency can cause metaplasia of specialized epithelia, such as the conjunctiva of the eye. Keratomalasia and myositis ossificans are associated with thickened conjunctiva and inflammation of skeletal muscle (converting to bone), respectively.
Dysplasia is a reversible condition unlike cancer, often caused by inflammation of skeletal muscle (trauma). An example is cervical intraepithelial neoplasia (CIN).
Aplasia is failure of cellular production during embryogenesis, an example is unilateral renal agenesis.
Hypoplasia is a decrease in cell production during embryogenesis, one example given is a streak ovary in Turner syndrome.

Cell Injury

Hypoxia is a decrease in blood flow through an organ (ischemia). This can be due to blockage in arteries or veins, or shock.

Cell Death

Necrosis is the death of a large group of cells, resulting in acute inflammation. Types of necrosis include coagulative necrosis, and liquefactive necrosis, where cell shape/architecture is retained while the tissue becomes loosely organized.
Apoptosis is the death of individual/small groups of cells, without the inflammatory response associated with necrosis. This process involves shrinkage of cells, which is followed by the removal of cellular components by macrophages.

Other

Example of oxygen carrying capacity decrease includes anemia, since normal oxygen levels may be bound by a dysfunctional hemoglobin (Hb).

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Description

This quiz focuses on the concepts of atrophy, autophagy, metaplasia, and dysplasia in cellular biology. It explores how these processes relate to cell size, functionality, and injury. Prepare to test your knowledge on these key adaptations and their implications for health and disease.