Anatomy and Physiology 141 - Unit 1

Chapter 1 Introduction to A&P, Chapter 2 Chemistry, Chapter 3 Cell Biology, Chapter 4 Tissues, Chapter 5 Integumentary System

Histology

The study of tissues and their structure. It involves examining the microscopic anatomy of cells and cellular components and is essential for understanding how tissues function in various organs.

Epithelial Tissue

A type of tissue that covers body surfaces, lines cavities, and forms glands. It plays roles in protection, absorption, secretion, and sensation.

Identify the Epithelial cell structure

Apical surface

Identify the Epithelial cell structure

Basal structure

Identify

Basal surface

Identify

Apical surface

Apical Surface

free unattached surface of an epithelial cell facing the body exterior or internal cavity

Basal surface

lower surface of an epithelial cell attached to the underlying basement membrane

Four major tissue types

Epithelial, connective, muscular, and nervous tissue.

Connective tissue

Supports, connects, and protects body structures.

Simple epithelium

Epithelium with one layer of cells.

Stratified epithelium

Epithelium with multiple layers of cells.

Transitional epithelium

Not quite stratified cuboidal specialized to stretch.

Pseudostratified epithelium

Single layer of cells of varying heights giving a false appearance of multiple layers, equipped with cilia (e.g., trachea lining).

Cilia

Hair-like structures that move and trap material across a cell surface.

Microvilli

Small projections that increase surface area.

Simple Squamous Epithelium

Single layer of flat, scale-like cells specialized for rapid diffusion and filtration (e.g., alveoli, capillaries).

Simple Cuboidal Epithelium

Single layer of cube-shaped cells specialized for secretion and absorption (e.g., kidney tubules, gland ducts).

Simple Columnar Epithelium

Single layer of tall, column-like cells specialized for absorption and secretion (e.g., digestive tract lining).

Tight junction

Intercellular junction that forms a leak-proof barrier sealing adjacent plasma membranes together.

Anchoring Junction

Cell junction anchoring actin filament networks between neighboring cells via cadherins.

Gap Junction

Protein channel (connexon) linking adjacent cells to allow direct passage of ions and small molecules.

(Epithelial) Structure Determines Function: Squamous, Cuboidal, Columnar
thinner, thicker
fragile, durable
Secretions: less, more
Diffusion: more less

Glands

Epithelial tissue that secrete substances

• Glands often produce the substances that they secrete

• Secretions are released from the apical surface

Exocrine Gland

Gland releasing secretions through ducts onto body surfaces (or surface of

epithelium) or into cavities (e.g., sweat, salivary glands).

Endocrine Gland

Ductless gland secreting hormones directly into interstitial fluid and bloodstream (e.g., thyroid, pituitary).

Merocrine Secretion

Secretory product released via exocytosis without loss of cellular material (e.g., eccrine sweat glands).

Apocrine Secretion

Secretory product released along with the apical portion of the cell membrane (e.g., mammary/pelvic/axillary glands).

Holocrine Secretion

Secretion accumulating within the cell until the entire cell ruptures and dies (e.g., sebaceous glands).

Simple Tubular Glands

A gland with an unbranched duct and a tubular secretory portion.

Simple Alveolar Glands

A gland with an unbranched duct and sac-like (alveolar) secretory portion.

Compound gland

A gland with a branched duct system.

Connective Tissue

Tissue type that binds, supports, protects, insulates, and transports substances throughout the body.

Extracellular Matrix (ECM)

Non-living material surrounding cells, composed of ground substance and protein fibers.
Provides structural and functional support.
ECM = fibers + ground substance

Protein fibers (for ECM)

One component of ECM; includes collagen, reticular, and elastic fibers.
strength, support, elasticity

Collagen fibers

Strong fibers that provide tensile strength.

Reticular fibers

Delicate fibers that form supportive networks.

Elastic fibers

Fibers that allow tissues to stretch and recoil.

Ground Substance

The gel-like, non-fibrous part of the ECM that supports cells, binds water (hydration), and provides cushioning/protection.

Mesenchymal cells

Undifferentiated connective tissue cells that can develop into other connective tissue cell types.

Fibroblasts

Connective tissue cells that produce the extracellular matrix (ECM), including fibers and ground substance.

Fibrocytes

Mature connective tissue cells that maintain the ECM.

Melanocytes

Cells that produce melanin, a pigment that contributes to coloration and helps protect cells from UV radiation.

Adipocytes

Fat cells specialized for storing lipids (fat).

Macrophages

Immune cells that engulf and digest pathogens, dead cells, and cellular debris through phagocytosis.

Neutrophils

White blood cells that respond quickly to infection and inflammation and destroy pathogens.

Mast cells

Immune cells that release chemicals involved in inflammation and allergic responses, including histamine.

Lymphocytes

White blood cells involved in specific/adaptive immune responses, including B cells and T cells.