Homeostasis, Animal Immunity, and Plant Defense Mechanisms

A set of vocabulary flashcards covering homeostasis, animal thermoregulation, the innate and adaptive immune systems, and plant defense mechanisms based on lecture transcript details.

Homeostasis

The process by which an organism maintains a dynamic equilibrium within its internal environment, keeping functions within a specific range around a set point.

Negative Feedback Loops

The predominant regulatory mechanism that counteracts a stimulus to move a physiological level back toward its normal set point to maintain stability.

Positive Feedback Loops

A mechanism that amplifies or maintains the direction of a stimulus, driving a system further away from its initial set point for rapid biological events like childbirth.

Endothermic

Animals that rely heavily on internal metabolic waste heat to stay warm, such as birds and mammals.

Ectothermic

Animals that rely on external environmental temperatures to set their body temperature, such as reptiles and amphibians.

Homeothermic

An organism that maintains a stable internal body temperature despite fluctuations in the external environment.

Poikilothermic

An organism whose internal temperature varies constantly with its immediate environment.

Vasoconstriction

The narrowing of peripheral blood vessels to keep warm blood clustered at the body core as a heat conservation mechanism.

Vasodilation

The widening of blood vessels near the skin surface to radiate heat away from the body as a heat dissipation mechanism.

Countercurrent Heat Exchange

A circulatory adaptation where warm arterial blood running to extremities exchanges heat with cold venous blood returning to the core, minimizing heat loss.

Innate Immunity

The non-specific branch of the immune system providing an immediate response with no immunological memory through barriers, phagocytes, and inflammation.

Adaptive Immunity

A highly specific immune branch with a delayed response that targets unique antigens and develops strong immunological memory via B cells and T cells.

Vaccine

A harmless, weakened, or dead component of a pathogen introduced to the body to generate a primary immune response and produce Memory B and T cells.

Antigen

Any foreign molecule, typically a protein or carbohydrate on a pathogen's surface, that triggers an immune response.

Antibody (Immunoglobulin)

A Y-shaped protein produced by B cells designed to bind precisely to a specific antigen, marking pathogens for destruction.

Neutralization

An antibody interaction where antibodies block the active sites of a virus or toxin, preventing them from infecting host cells.

Opsonization

The process where antibodies coat a pathogen to act as a flag, making it easier for phagocytic cells like macrophages to recognize and engulf it.

Agglutination

The clumping together of pathogens caused by antibodies binding to antigens on separate invaders simultaneously.

Complement Activation

A cascade of blood proteins triggered by antibody binding that punctures holes in a pathogen's cell membrane, causing it to burst.

Neutrophils

The most abundant white blood cells and rapid responders that arrive first at infection sites to engulf bacteria via phagocytosis.

Macrophages

Large, long-lived phagocytes that engulf pathogens and act as Antigen-Presenting Cells ($APCs$) to alert T cells.

Natural Killer ($NK$) Cells

Innate lymphocytes that identify and destroy compromised host cells, such as tumor or virus-infected cells, by forcing them into apoptosis.

B Cells

Lymphocytes that mature in the bone marrow and differentiate into plasma cells to orchestrate humoral (antibody-mediated) immunity.

Helper T Cells ($CD4^+$)

The "generals" of the immune system that secrete cytokines to activate and coordinate B cells, cytotoxic T cells, and macrophages.

Cytotoxic T Cells ($CD8^+$)

T cells that directly target and kill infected host cells or cancer cells by releasing perforins and granzymes.

Lysozyme

An enzyme found in tears, saliva, and mucus that breaks down the peptidoglycan cell walls of bacteria.

Bone Marrow

Primary lymphoid organ where hematopoiesis occurs and where B cells undergo maturation.

Thymus

A gland in the upper chest where immature T cells migrate from the bone marrow to undergo selection and maturation.

Spleen

A secondary lymphoid organ that filters blood, destroys old red blood cells, and clears blood-borne pathogens.

Peyer's Patches

Clusters of lymphoid tissue in the small intestine lining that monitor gut microbiota and prevent pathogenic breaches.

Trichomes

Microscopic hair-like projections on plant surfaces that physically obstruct insects or secrete toxic substances.

Phytoalexins

Antimicrobial compounds synthesized rapidly on-demand by plants in response to a pathogen attack, such as resveratrol.

Alkaloids

Nitrogen-containing secondary metabolites, such as caffeine or nicotine, that disrupt the nervous systems of animals and insects.

Tannins

Polyphenolic compounds in plants that inactivate digestive enzymes in an herbivore's gut, making plant material bitter and indigestible.

Cyanogenic Glycosides

Plant compounds that release toxic hydrogen cyanide ($HCN$) when tissue is damaged by chewing, halting cellular respiration in attackers.

PAMP-Triggered Immunity ($PTI$)

The first tier of plant immunity where Pattern Recognition Receptors ($PRRs$) recognize conserved molecular signatures like fungal chitin.

Effector-Triggered Immunity ($ETI$)

A high-voltage plant immune response triggered when Resistance ($R$) proteins intercept specialized pathogen effectors.

Callose Deposition

The rapid synthesis of a carbohydrate polymer into the plant cell wall at the site of attack to reinforce the wall against invaders.

Hypersensitive Response ($HR$)

A localized form of Programmed Cell Death ($PCD$) in plants that starves pathogens by intentionally destroying infected tissue.

Systemic Acquired Resistance ($SAR$)

A delayed, whole-body plant immunization triggered by mobile signals like Salicylic Acid ($SA$) that primes uninfected tissues against future attacks.

Homeostasis

The process by which an organism maintains a dynamic equilibrium within its internal environment, keeping functions within a specific range around a set point.

Factors affecting Homeostasis

Factors that can affect homeostasis include temperature, pH levels, hydration status, and nutrient availability.

Negative Feedback Loops

The predominant regulatory mechanism that counteracts a stimulus to move a physiological level back toward its normal set point to maintain stability.

Positive Feedback Loops

A mechanism that amplifies or maintains the direction of a stimulus, driving a system further away from its initial set point for rapid biological events like childbirth.

Endothermic Animals

Animals that rely heavily on internal metabolic heat to stay warm, such as birds and mammals.

Ectothermic Animals

Animals that rely on external environmental temperatures to set their body temperature, such as reptiles and amphibians.

Homeothermic Animals

An organism that maintains a stable internal body temperature despite fluctuations in the external environment.

Poikilothermic Animals

An organism whose internal temperature varies constantly with its immediate environment.

Heat Conservation Mechanisms

Ways animals conserve heat include vasoconstriction, countercurrent heat exchange, and insulating body structures.

Heat Dissipation Mechanisms

Ways animals dissipate heat include vasodilation and behavioral adaptations like seeking shade or water.

Countercurrent Heat Exchange

A circulatory adaptation where warm arterial blood running to extremities exchanges heat with cold venous blood returning to the core, minimizing heat loss.

Innate Immunity

The non-specific branch of the immune system providing an immediate response with no immunological memory through barriers, phagocytes, and inflammation.

Adaptive Immunity

A highly specific immune response that targets unique antigens and develops strong immunological memory via B cells and T cells.

Immunological Memory

The ability of the immune system to remember and respond more effectively to previously encountered pathogens.

Vaccine

A harmless, weakened, or dead component of a pathogen introduced to the body to generate a primary immune response and produce Memory B and T cells.

Antigen-Antibody Interactions

Antibody interaction where antibodies bind to specific antigens, marking pathogens for destruction.

B Cells

Lymphocytes that mature in the bone marrow and differentiate into plasma cells to orchestrate humoral (antibody-mediated) immunity.

T Cells

Lymphocytes that respond to infected or cancerous cells; includes Helper T Cells (coordinate immune response) and Cytotoxic T Cells (kill infected cells).

Natural Killer (NK) Cells

Innate lymphocytes that identify and destroy compromised host cells, such as tumor or virus-infected cells.

Macrophages

Large phagocytes that engulf pathogens and act as Antigen-Presenting Cells (APCs) to alert T cells.

Dendritic Cells

Professional antigen-presenting cells that capture and present antigens to T cells, initiating adaptive immunity.

Physical Barriers

First line of defense including skin and mucous membranes preventing pathogen invasion.

Chemical Barriers

Includes substances like enzymes and antimicrobial peptides that inhibit pathogen growth.

Lymph Node

Major organ that filters lymph, houses immune cells, and facilitates immune response.

Bone Marrow

Primary lymphoid organ where hematopoiesis occurs and where B cells undergo maturation.

Thymus

A gland where immature T cells migrate from the bone marrow to undergo selection and maturation.

Spleen

A secondary lymphoid organ that filters blood, destroys old red blood cells, and clears blood-borne pathogens.

Peyer's Patches

Clusters of lymphoid tissue in the small intestine that monitor gut microbiota and prevent pathogenic breaches.

Hypersensitive Response (HR)

A localized form of programmed cell death in plants that starves pathogens by intentionally destroying infected tissue.

Systemic Acquired Resistance (SAR)

A delayed, whole-body plant immunization triggered by mobile signals that primes uninfected tissues against future attacks.