Medical Entrance Preparation Zoology Review

Comprehensive vocabulary flashcards covering evolutionary biology, invertebrate and vertebrate diversity, animal histology, human physiology, infectious diseases, immunology, applied biotechnology, and ecology.

Biogenetic Law

The evolutionary principle formulated by Ernst Haeckel stating that ontogeny recapitulates phylogeny, meaning an organism repeats its racial ancestral history during embryonic development.

Homologous Organs

Organs that share a common embryonic origin and basic structural framework but may serve different functions, illustrating divergent evolution (such as human forelimbs, horse forelimbs, and bat wings).

Analogous Organs

Structures that possess different embryonic origins and structural anatomy but carry out similar functions as a result of convergent evolution (such as mosquito wings, bat wings, and sparrow wings).

Atavism

The sudden reappearance of ancestral ancestral morphological traits or features in an organism that were lost in recent evolutionary history, such as a child born with a tail.

Adaptive Radiation

An evolutionary process in which an ancestral group rapidly diversifies into a large variety of new forms specifically adapted to distinct ecological niches and habitats.

Choanocytes

Flagellated collar cells unique to the phylum Porifera that line the internal cavities (choanoderm) and assist in water circulation and nutrition.

Radula

A chitinous, rasping tongue-like feeding organ present in the mouth cavity of molluscs, used to scrape and gather food.

Water Vascular System

A specialized hydraulic, enterocoelic canal network found characteristically in echinoderms that facilitates locomotion via tube feet, food capture, and respiration.

Organ of Bojanus

The excretory organ found in molluscs that functions in waste excretion and osmoregulation.

Sarcomere

The fundamental structural and functional contractile unit of striated muscle tissue, bounded between two successive Z-discs.

Volkmann Canal

A microscopic transverse channel in compact bone connecting longitudinal Haversian canals to one another and to the periosteum.

Nissl Granules

Ribonucleoprotein complexes composed of rough endoplasmic reticulum and free ribosomes located within the cyton of a neuron for protein synthesis.

Astrocytes

The most abundant type of neuroglial cells in the central nervous system, playing a critical structural role in maintaining the blood-brain barrier.

Schwann Cells

Glial cells of the peripheral nervous system responsible for synthesizing and wrapping the insulating myelin sheath around peripheral nerve axons.

Bidder's Canal

A specialized longitudinal canal located within the anterior kidney of male frogs that receives vasa efferentia to conduct spermatozoa.

Chloragogen Cells

Yellow-brown excretory and glycogen-storage cells surrounding the alimentary canal of earthworms (Pheretima), functionally analogous to the vertebrate liver.

Typhlosole

A prominent internal dorsal fold of the intestinal wall in earthworms that increases the effective surface area for nutrient absorption.

Ookinete

The motile, vermiform diploid zygote stage of Plasmodium that penetrates the gut wall of the female Anopheles mosquito.

Haemozoin

A dark crystalline, toxic malarial pigment produced by Plasmodium during the digestion of host erythrocyte hemoglobin, which triggers chills and fever upon release.

Ora Serrata

The serrated junction in the human eye marking the transition between the non-photosensitive ciliary body and the photosensitive retina.

Organ of Corti

The sensory receptor organ for hearing situated upon the basilar membrane within the cochlear duct (scala media) of the internal ear.

Pneumotaxic Center

A neural control center located in the pons varolii of the brain that modulates the respiratory rhythm generator in the medulla.

Bohr Effect

The physiological reduction in hemoglobin's oxygen-binding affinity caused by an elevation in blood carbon dioxide concentration or decreased blood pH.

Hamburger Phenomenon

The chloride shift mechanism wherein bicarbonate ions leave red blood cells in exchange for plasma chloride ions to maintain electrical neutrality during carbon dioxide transport.

Kupffer Cells

Specialized resident macrophages lining the sinusoids of the liver that phagocytize worn-out erythrocytes and foreign matter.

Crypts of Lieberkühn

Tubular mucosal glands found in the small intestine that secrete succus entericus and house enzyme-secreting Paneth cells.

DOTS

Directly Observed Treatment Short-course, the standardized international therapeutic management regimen designed for treating and eradicating tuberculosis.

Humoral Immunity

Adaptive immune protection mediated by B-lymphocytes and their differentiated plasma cells through the secretion of antigen-specific antibodies into blood and lymph.

Cell-Mediated Immunity

Adaptive immunity governed directly by T-lymphocytes (such as cytotoxic T-cells and helper T-cells) without reliance on circulating antibodies, notably mediating allograft rejection.

Passive Immunity

Short-lived immunity conferred to a recipient by the direct transfer of preformed antibodies, providing immediate protection without creating immunological memory.

Biomagnification

The progressive increase in concentration of persistent, non-biodegradable chemicals (such as organochlorines like DDT) at successively higher trophic levels of a food chain.

Eutrophication

The excessive nutrient enrichment of aquatic ecosystems with nitrates and phosphates, triggering dense algal blooms and subsequent severe depletion of dissolved oxygen.

Anadromous Migration

The reproductive migration pattern in which marine fishes (such as salmon) swim from saltwater environments upstream into freshwater bodies to spawn.

Catadromous Migration

The migratory behavior wherein freshwater fishes travel downstream into the sea or ocean to spawn.

Autotomy

The defensive behavior of self-amputating or shedding a limb or caudal appendage (such as a lizard discarding its tail) when threatened by a predator.

Cursorial Adaptation

Morphological and anatomical adaptations specialized for rapid running, typically characterized by slender elongated limbs, digit reduction, and digitigrade locomotion.