Biology Lecture: Tissues, Junctions, and Membranes

Flashcards covering the classification of epithelial and connective tissues, cellular junctions, membrane types, and glandular secretion mechanisms according to the lecture transcript.

Main Rule of Osmosis

Water follows the solute; water moves towards areas where there is a higher concentration of solute.

Hypertonic Solution

A solution with a higher concentration of solute (e.g., $5\,\%$) relative to a cell (e.g., $3\,\%$), causing water to move out and the cell to shrivel like a raisin.

$$AUG$$

The first codon added during the process of translation.

Codon

A set of $3$ nucleotides that the ribosome reads in order to add amino acids onto a protein chain.

Tissue

Groups of cells that perform the same function, which can be organized or unorganized.

Main Tissue Types

The $4$ primary categories of tissue in the body: connective, nervous, epithelial, and muscular.

Epithelial Tissue

A main tissue type whose job is to line body surfaces and cavities, such as the skin.

Connective Tissue

A main tissue type that connects parts of the body and provides structural support.

Muscular Tissue

A main tissue type responsible for helping with movement.

Nervous Tissue

A main tissue type that revolves around sending and receiving electrical signals.

Junction

A structure used to stick $2$ cells together.

Tight Junction

A junction that acts like a zipper, completely sealing off intercellular space to form a watertight seal, found in the stomach and bladder.

Gap Junction

A junction that functions like a gate using proteins called connexons, which can open and close to allow substances to move between cells.

Desmosome

A small anchoring point similar to a spot weld that connects to the cytoskeleton of the cell to resist mechanical stresses like twisting or pulling.

Hemidesmosome

An anchoring point found at the bottom of a cell that connects it to the basement membrane.

Basement Membrane

A line or layer that sits at the bottom of epithelial tissue, anchoring it to underlying connective tissue.

Avascular

A characteristic of tissue, such as epithelia and cartilage, meaning it has no blood vessels or direct blood supply.

Squamous

Epithelial cells that are flattened or squished in shape.

Cuboidal

Epithelial cells that are round or cube-shaped.

Columnar

Epithelial cells that are taller than they are wide, shaped like rectangles or columns.

Simple Epithelium

Epithelial tissue consisting of only $1$ row or layer of cells.

Stratified Epithelium

Epithelial tissue consisting of multiple rows or layers of cells.

Pseudostratified Columnar Epithelium

A type of tissue that looks like it has multiple layers because of misplaced nuclei, but is actually a single layer of cells; primarily found in the respiratory tract.

Alveoli

Little air-filled sacs in the lungs where oxygen and carbon dioxide diffuse across simple squamous epithelium.

Simple Cuboidal Epithelium

A single row of cube-shaped cells good for secreting substances like mucus in mammary glands, the liver, and salivary glands.

Stratified Cuboidal Epithelium

Multiple layers of cube-shaped cells found in sweat glands, ovaries, and seminiferous tubules to help produce sweat, hormones, or sperm.

Microvilli

Little tiny hair-like projections on the tops of columnar cells that move in order to transport substances or aid in absorption.

Transitional Epithelium

A type of epithelial tissue where cells can change shape from round to flat; found in the bladder to allow for stretching as it fills with urine.

Matrix

The space between the widely spread-apart cells in connective tissue.

Matrix Fibers

The $3$ main fibers found in connective tissue matrix: collagen (strength), reticular (framework/net), and elastic (stretch and bounce back).

Areolar Connective Tissue

A type of loose fibrous tissue found beneath the skin and between muscles that is highly vascular, providing blood and nutrients to the epithelial tissue above it.

Reticular Tissue

A net-like tissue that forms the framework for lymphatic organs such as lymph nodes, the spleen, thymus, and bone marrow.

Dense Regular Connective Tissue

Tissue with organized fibers lined up in the same direction, making up tendons and ligaments.

Dense Irregular Connective Tissue

Tissue with fibers that lack a specific organizational pattern, allowing it to withstand unpredictable mechanical stresses; found deep in the skin.

Adipose Tissue

Fatty tissue made of cells with giant lipid droplets that provide insulation, cushioning, and energy storage.

Chondrocyte

A cartilage cell located within a small space in the tissue.

Hyaline Cartilage

A stiff, non-bending type of cartilage that is structurally sound; found in joints, attached to ribs, in the trachea, and in the larynx.

Fibrocartilage

A type of cartilage rich in fibers found in intervertebral discs; it provides strength, weight-bearing functions, and resists compression.

Elastic Cartilage

A flexible or bendy type of cartilage found in the ear and the epiglottis.

Compact Bone

Bone tissue organized into concentric circles with no visible spaces between cells.

Plasma

The matrix found in blood tissue that surrounds red blood cells, white blood cells, and platelets.

Synovial Membrane

A type of membrane found around joint cavities that consists only of connective tissue and contains no epithelial tissue.

Exocrine Gland

A gland that uses a duct (a small passageway) to secrete products like sweat, tears, or oil, typically outside the body.

Endocrine Gland

A ductless gland that secretes products, such as hormones, directly into the bloodstream.

Eccrine (Merocrine) Secretion

A secretion method where products are packaged by the Golgi into vesicles and released through exocytosis.

Apocrine Secretion

A secretion method where a portion of the cell breaks off and is released along with the product, as seen in mammary glands.

Holocrine Secretion

A dramatic secretion method where cells build up product until they explode, releasing secretions and dead cell parts; found in oil glands.