Ammonia is highly water-soluble and can be toxic to cells at low concentrations due to presence of its ammonium ion, which can interfere with oxidative phosphorylation. Ammonia is small and can easily diffuse through cell membranes, making it easy to excrete. Essentially, there is a trade off of easy excretion and toxicity levels.

For aquatic animals, however, toxicity is negligible due to the large volume of water available to dilute ammonia wastes. The high solubility of ammonia wastes and the abundance of water solvent allow for the ammonia to be transported out of cells in an very dilute concentration, without harming the organism. This allows aquatic organisms to conserve energy, compared to terrestrial organisms that must convert ammonia wastes to other forms.

Amphibians and mammals convert ammonia to urea, which can be excreted with less water, but must still be relatively dilute. These animals release liquid wastes from the body, resulting in water loss, but conserve energy compared to organisms that continue to convert urea into uric acid. Birds and reptiles excrete uric acid, which requires very little water waste, but uses a larger amount of energy in conversion. This is beneficial to animals that may not have ready access to fresh water.

There is a key trade-off between energy consumption and toxicity in the excretion of nitrogenous wastes. Ammonia is the simplest form of the waste product, and requires very little energy to produce; however, it is highly toxic and must be diluted to extremely low concentrations in order to be safe to the cells. Many aquatic animals excrete ammonia because of their proximity to water. Access to large amounts of water means that these organisms can safely excrete dilute ammonia without needing to use energy in conversions.

Terrestrial animals, with less access to water, excrete urea or uric acid. These wastes are derived from ammonia, but require an input of energy for the conversion. They are less toxic and require less water loss for dilution, making them ideal for animals that must conserve fluids. Uric acid is the least toxic of the nitrogenous wastes, but also requires the greatest energy investment.

Alcohol decreases the activity of antidiuretic hormone (vasopressin). A diuretic increases the production of urine and thus, inhibition of this antidiuretic hormone results in an increase in the production of highly diluted urine.

Alcohol does not block the flow of fluids through the kidney tubules.

Proteins would not be found in the urine because these molecules are too large to pass through the glomerulus of the nephron of the kidney. They would be filtered out and remain in the bloodstream. Meanwhile, all of the other compounds would be present in normal urine. 

The body has a generalized group of phagocytic cells that can attack microbes that have made it past the skin. Macrophages and neutrophils are the first cells to respond to an infection. Monocytes will later migrate from the bloodstream into the body tissues and phagocytize pathogens. T-cells are part of the acquired immune system and are only present after a specific pathogen had been previously encountered in the body.

Natural passive immunity is conveyed from mother to child in-utero or through colostrum in breast milk.  Natural passive immunity provides temporary immunity to many diseases.

Natural active immunity occurs when an individual develops a disease as a result of being exposed to a live pathogen, and acquires immunity to that pathogen as a result.

Artificial active immunity is acquired as a result of intentional exposure to a pathogen, as in a vaccination.

Artificial passive immunity occurs when antibodies are transferred from one person to another. Immediate short-term protection may be conveyed to immune-compromised patients, such as chemotherapy recipients, by this mean.

Essentially, active immunity requires exposure to a live pathogen; passive immunity does not (only antibodies). Artificial immunity requires intervention in the form of a vaccine or medical care, while natural immunity occurs unintentionally through exposure.

Toll-like receptors (TLRs) are a family of receptors found within innate immune antigen-presenting cells such as dendritic cells, monocytes, and macrophages. These receptors recognize specific elements of various infectious agents such as lipopolysaccharides, DNA, and RNA. Binding and activation of these receptors stimulates inflammatory responses and CD4/CD8 T-cell responses to drive an effective immune response.

TLRs do not control B-cell clonal selection, the process by which B-cells replicate to amplify the production of a certain antibody.

Innate immunity is a generalized form of protection against pathogens in the body. The cells of innate immunity generally attack all types of invasive agents and do not interact with antibody production.

Neutrophils, eosinophils, and macrophages are all generalized leukocytes that are present in the body. Neutrophils, basophils, and eosinophils are the primary granulocytes, all of which are involved in innate immunity. Macrophages are differentiated monocytes, capable of phagocytosis against non-specific invaders.

Plasma cells are differentiated B-lymphocytes. They release antibodies into the bloodstream that are specific for a given pathogen. As a result, plasma cells are only present following a specific infection. They are a crucial part of the adaptive immune response, but are not involved in innate immunity.

An acquired immune response to a secondary infection by a pathogen results in presentation of antigen to residual memory helper T-cells, memory T-cells, and memory B-cells. Upon recognizing the antigen, memory T-cells can become cytotoxic T-cells and target the infected region. The process of presentation promotes direct expansion of the existing population of immune cells already capable of responding to the pathogen. Immunological memory provides a more rapid response time to combat the pathogen during the second exposure.

Innate defenses, such as skin and macrophages, are a primary defense against all diseases, but adaptive immunity is related to exposure to a specific disease. The ability for the body to produce specific antibodies quickly provides adaptive immunity. While some antibodies may remain in the blood after initial exposure, this small amount does not provide sufficient immunity. 

The specific lymphocytes that produce antibodies during a second exposure are called memory B-cells. When an antigen is presented to a memory B-cell that produces the appropriate antibody, the cell divides and differentiates into plasma cells. Plasma cells are then responsible for producing large amounts of antibodies against the specific antigen. Antibodies are cell-surface markers that attach to pathogens, signaling effector cells to rapidly destroy the pathogen. The rapid multiplication of B-cells to generate antibody to a specific threat is known as clonal selection.