Modules 6-8: Cell Division, Histology, and Anatomical Orientations

Comprehensive vocabulary flashcards covering bacterial and eukaryotic cell division (mitosis and cytokinesis), vertebrate histology and tissue identification (epithelial, connective, muscular, nervous), anatomical orientations, directional terminology, planes, and comparative vertebrate structures.

Binary Fission

The asexual replication process of bacterial cells where the chromosome replicates from the origin to the terminus, the cell elongates, and a septum forms to divide the parent cell into two daughter cells.

Chromatin

The structural complex composed of DNA and proteins that forms eukaryotic chromosomes.

Homologous Chromosomes

The two non-identical chromosomes that make up a matched pair in diploid cells, with one chromosome inherited from the mother and one from the father.

Sister Chromatids

The two identical copies of a chromosome produced during DNA replication, held together at the centromere.

Kinetochore

A disk-shaped protein complex located at the centromeric region of a chromosome where spindle microtubules attach during cell division.

Centromere

The specific constricted region of a replicated chromosome where sister chromatids connect.

Cohesin Proteins

Protein complexes that physically hold sister chromatids together along their length following replication.

$G_1$ Phase

The primary growth phase of interphase where the cell spends the majority of its life producing proteins and performing metabolic functions.

$S$ Phase

The synthesis phase of interphase during which the cell replicates its genomic DNA.

$G_2$ Phase

The secondary growth phase of interphase that prepares the cell for mitosis by condensing chromosomes, replicating organelles, and synthesizing tubulin.

Prophase

The initial stage of mitosis characterized by DNA condensation making chromosomes visible under a microscope, assembly of the mitotic spindle apparatus, and breakdown of the nuclear envelope.

Prometaphase

The mitotic stage where kinetochore microtubules from the spindle apparatus attach directly to the kinetochores of paired sister chromatids.

Metaphase

The mitotic stage during which chromosomes align along the equator of the cell along an imaginary plane called the metaphase plate.

Anaphase

The mitotic stage during which cohesin proteins degrade and sister chromatids are pulled apart toward opposite poles of the dividing cell.

Telophase

The final stage of nuclear division where the spindle apparatus disassembles, the nuclear envelope reforms around each daughter set of chromosomes, and chromosomes decondense.

Cytokinesis

The physical division of the cytoplasm into two daughter cells, occurring via a cleavage furrow in animal cells and a cell plate in plant cells.

Kinetochore Microtubules

Spindle fibers that attach to the kinetochores of sister chromatids and shorten during anaphase to pull chromatids toward the spindle poles.

Polar Microtubules

Spindle fibers extending from opposite centrosomes toward the center of the cell that elongate during anaphase to push the poles apart.

Astral Microtubules

Short spindle microtubules that radiate outwards toward the plasma membrane to anchor and properly orient the mitotic spindle apparatus.

Avascular

A biological tissue characteristic denoting the lack of direct blood vessels supplying nutrients, as seen in epithelial tissue.

Apical Surface

The unattached, free border or surface of an epithelial tissue that faces the body exterior or the lumen of an internal cavity.

Basal Surface

The anchored surface of epithelial cells attached to underlying connective tissue or a basement membrane.

Lateral Surface

The contact surface between two adjacent epithelial cells in a tissue layer.

Simple Squamous Epithelium

A single layer of flattened epithelial cells with flat nuclei that lines alveolar air sacs, blood capillaries, kidney structures, and body cavity linings.

Stratified Squamous Epithelium (Non-Keratinized)

A multilayered tissue with living flattened apical cells, specialized to resist abrasion in moist openings such as the oral cavity, esophagus, vagina, and anus.

Stratified Squamous Epithelium (Keratinized)

A multilayered epithelial tissue whose outer surface consists of dead cells filled with protective keratin, comprising the epidermis of the skin.

Simple Cuboidal Epithelium

A single layer of cube-shaped cells with central round nuclei, found lining kidney tubules, ovary surfaces, and glandular ducts such as those of the thyroid.

Simple Columnar Epithelium

A single layer of tall, column-like cells with oval nuclei, goblet cells, and apical microvilli or cilia; found in the stomach, intestines, fallopian tubes, and bronchioles.

Pseudostratified Ciliated Columnar Epithelium

A single cell layer appearing stratified due to staggered nuclear levels, possessing surface cilia and goblet cells to clear mucus in the upper respiratory tract.

Goblet Cell

A specialized mucus-secreting epithelial cell that appears as a pale or clear bubble-like structure within columnar epithelial layers.

Fibroblast

The predominant cell type in connective tissue proper that synthesizes and secretes fibrous extracellular matrix proteins including collagen and elastin.

Loose Connective Tissue (Areolar)

A connective tissue containing fibroblasts and a meshwork of thick pink collagen fibers and thin purple elastin fibers, located under all epithelial tissues and around organs.

Dense Regular Connective Tissue

A connective tissue characterized by densely packed, parallel arrays of collagen fibers interspersed with rows of fibroblasts, forming tendons and ligaments.

Reticular Connective Tissue

A connective tissue featuring an intricate network of dark reticular fibers that provides internal scaffolding for immune organs like lymph nodes and bone marrow.

Osteon (Haversian System)

The basic structural and functional repeating unit of compact bone tissue consisting of concentric lamellae arranged around a central canal.

Haversian Canal

The central longitudinal channel of an osteon through which blood vessels and nerve fibers travel.

Lamellae

Concentric rings of mineralized extracellular bone matrix that surround the central Haversian canal.

Osteocytes

Mature bone cells that reside inside lacunae and maintain bone matrix metabolism.

Lacunae

Small cavities or crevices located within the extracellular matrix of bone and cartilage that house osteocytes or chondrocytes.

Canaliculi

Microscopic hair-like canals penetrating bone lamellae that interconnect lacunae with each other and with the Haversian canal.

Chondrocytes

Cartilage cells residing within lacunae that produce and maintain the surrounding chondrin matrix.

Chondrin

The firm, gelatinous extracellular matrix characteristic of cartilage tissues.

Hyaline Cartilage

A smooth cartilage with a homogenous chondrin matrix and lacunae-enclosed chondrocytes, found at articular bone ends, the nose, costal ribs, larynx, and trachea.

Elastic Cartilage

A flexible cartilage containing dense networks of elastin fibers within its chondrin matrix, found in the external ear and larynx.

Plasma

The fluid intercellular matrix that suspends the cellular elements of blood tissue.

Erythrocytes

Anucleated biconcave red blood cells containing hemoglobin for oxygen transport that stain pink under a light microscope.

Leukocytes

Nucleated white blood cells that fight infection and defend the immune system, staining dark purple under the microscope.

Platelets

Enucleated fragments of large bone-marrow cells that circulate in blood to facilitate blood clotting.

Adipocyte

A specialized cell found in adipose tissue that stores energy in a large intracellular lipid droplet composed of triglycerides.

Skeletal Muscle

Voluntary, striated muscle tissue attached to bones that exhibits alternating bands of actin and myosin filaments perpendicular to cell length.

Smooth Muscle

Involuntary, non-striated spindle-shaped muscle tissue found within the walls of hollow organs including the stomach, intestines, bladder, uterus, airways, and blood vessels.

Cardiac Muscle

Involuntary, striated muscle tissue found exclusively in the heart wall, characterized by branching fibers and specialized intercalated discs.

Intercalated Discs

Specialized cellular junctions between adjacent cardiac muscle cells that coordinate cellular contraction across continuous functional fibers.

Neurons

Excitable nervous tissue cells that generate and propagate electrical nerve impulses.

Schwann Cells

Glial support cells in peripheral nervous tissue that help propagate nerve impulses and provide metabolic nourishment to neurons.

Superior

Anatomical term indicating a structure is higher or positioned above another part of the body.

Inferior

Anatomical term indicating a structure is lower or positioned below another part of the body.

Medial

Anatomical directional term meaning toward or closer to the midline of the body.

Lateral

Anatomical directional term meaning away from the midline toward the outer side of the body.

Proximal

Anatomical directional term meaning closer to the point of attachment or trunk of the body.

Distal

Anatomical directional term meaning farther away from the point of attachment or trunk of the body.

Coronal Plane

A vertical plane (also called frontal plane) that divides the body into dorsal (posterior) and ventral (anterior) portions.

Transverse Plane

A horizontal cross-sectional plane that divides the body into superior and inferior portions.

Sagittal Plane

A vertical plane dividing the body into left and right sides, either as equal halves (midsagittal) or unequal sections (parasagittal).

Homologous Structures

Morphological features in different species that share a common ancestral origin or developmental pathway, even if they perform different functions.

Analogous Structures

Morphological features in different species that perform similar functions but evolved independently without sharing a common ancestor.