Harvard Human Anatomy - Cells, Tissues and Systems

Cell

The smallest independent unit of living tissue, composed of molecules and organized by membranes.

Cell membrane

A selective barrier between the interior and exterior of the cell.

Circulatory System

Distributes body fluids, enabling transport of oxygen and nutrients and removal of CO2 and waste.

Cytoplasm

Comprised of the cytoskeleton suspended in cytosol.

Digestive system

Chief functions include absorption of water and breakdown and absorption of food.

Endocrine system

Synthesizes and secretes hormones disseminated through the circulatory system.

Epithelial tissue

Forms a barrier covering external and internal body surfaces.

Endoplasmic reticulum (ER)

A system of membrane-bound tubules and cisternae within the cell.

Rough endoplasmic reticulum

major site of protein and enzyme synthesis within the cell. membrane surface is covered with ribosomes.

Smooth endoplasmic reticulum

found in cells specializing in hormone synthesis or detoxification

Golgi apparatus

Sorts and packages proteins produced in the rough endoplasmic reticulum.

Histology

The study of the minute structure of cells, tissues, and organs in relation to their functions.

Lysosomes

Small membrane-bound packets of enzymes that digest microorganisms and cell debris.

Mitochondria

Principal energy sources of cells, sites of oxidative phosphorylation and ATP formation. Numerous in cells that actively secrete protein,

Muscle tissue

Basic function is motion achieved by contraction and sliding of filament arrays.

Musculoskeletal system

Achieves motion, comprising bones, joints, muscles, and fascia.

Nervous tissue

Basic function is sending and receiving information.

Nervous system

Enables communication between the central nervous system and other body regions.

Nucleus

Contains genetic material, serves as the cell control center.

Nucleolus

Site of ribosomal RNA synthesis and ribosome assembly within the nucleus.

Organelle

Functional components of cells, including the nucleus, mitochondria, endoplasmic reticula, etc.

Peroxisomes

Membrane-bound packets of enzymes that oxidize organic substances and form hydrogen peroxide.

Respiratory system

Consists of a conducting portion (the airway) and a gas exchange portion (the alveoli).

Skin

The largest organ of the body, consisting of an outer epidermis and an inner dermis.

Supportive / Connective Tissue

Includes building materials and structural supports like fat, tendons, bone, and cartilage.

Urogenital system

Includes the urinary system and the male and female reproductive systems.