Pharmacognosy and Plant Anatomy Overview

Pharmacognosy Overview

• Pharmacognosy is the science of nature-derived medicines, pharmaceuticals, and poisons.
• The American Society of Pharmacognosy defines it as the study of the physical, chemical, biochemical, and biological properties of drugs from natural origins.
• It encompasses the search for new drugs from natural sources.
• Key fields within pharmacognosy include:
  • Medical Ethnobotany: the study of traditional plant use in a society.
  • Ethnopharmacology: the study of the pharmacological evaluation of traditionally used natural drugs.
  • Phytotherapy (medical herbalism): the use of plants and plant extracts for therapeutic purposes.
  • Phytochemistry (Natural Product Chemistry): the chemical study of bioactive constituents in plants, crucial for new drug discovery.

Plant Anatomy

• Plant anatomy describes the structure and organization of plant cells, tissues, and organs.
• It relates the structure to their development and function.
• It focuses on the structure of plant cells and tissues.

Cell Theory & Structure

• All living organisms are made up of cells.
• Cells are the smallest working units of all living organisms.
• A cell is the smallest unit capable of performing life functions.

Typical Plant Cell

• A typical plant cell has several key parts:
  • Plasma Membrane
  • Peroxisome
  • Chloroplast
  • Vacuole
  • Golgi Apparatus
  • Ribosomes
  • Plasmodesmata
  • Mitochondria
  • Smooth Endoplasmic Reticulum
  • Rough Endoplasmic Reticulum
  • Nucleus
  • Nucleolus
  • Nuclear Envelope
  • Cell Wall

Plant Cell Parts

• A plant cell is composed of living and non-living material
• Three main components:
  • Cell wall (non-living)
  • Protoplast (living material within the cell wall)
  • Vacuoles (non-living)

Cell Wall

• The cell wall is semi-rigid and non-selectively permeable.
• It is present in plant cells but absent in animal cells.
• It provides protection and support to the cell.
• It's composed of:
  • Middle lamella
  • Primary cell wall
  • Secondary cell wall

Middle Lamella

• The middle lamella is the first partition between two adjacent plant cells.
• Primarily composed of calcium and magnesium pectate.

Primary Cell Wall

• Thin and characteristic of young, growing cells.
• Composed primarily of cellulose molecules.
• Capable of expansion as the cell grows.

Secondary Cell Wall

• Thicker and stronger than primary walls.
• Forms after cell expansion is complete.
• Composed of cellulose, hemicellulose, lignin, and suberin.
• Incapable of increasing in area after formation.

Pits and Plasmodesmata

• Pits are areas in the secondary cell wall where no secondary wall material is deposited.
• Pits enable materials and stimuli to pass between adjacent cells.
• Plasmodesmata are strands of cytoplasm that connect the protoplasts of adjacent cells.
• Aid in cell-to-cell communication and material transport.
• Three types of pits exist: simple, bordered, and half-bordered

Protoplast

• The protoplast is the living component of a plant cell.
• It excludes any non-living components, like crystals, starch grains, and vacuole contents.
• It includes the plasma membrane, cytoplasm, and nucleus.

Plasma Membrane

• The plasma membrane is a phospholipid bilayer.
• It acts as a barrier, regulating the passage of substances into and out of a cell.

Cytoplasm

• The cytoplasm is the gelatinous fluid inside the cell.
• It holds and suspends organelles.

Plastids

• Plastids exist in plant cells and are of three types
  • Chloroplasts
  • Chromoplasts
  • Leucoplasts

Vacuole

• Vacuoles are plant cell structures containing cell sap.
• Cell walls may have thin film of cytoplasm.
• Filled with fluids, including pigments and other substances.
  • Membranes surround vacuoles.
  • Vacuoles contain pigments (e.g., anthocyanins) which colour petals and other parts of plants.

Ergastic Substances

• Ergastic substances are non-living components in plant vacuoles.
• Types include carbohydrates, proteins, and mineral crystals.

Carbohydrates

• Stored as starch grains which can be simple, semi-compound or compound.

Proteins

• Stored in structures called aleurone grains.
• Aleurone grains include structures named crystalloids and globoids.

Mineral Crystals

• Mainly calcium oxalate or carbonate.
• Can take different forms in cells; such as solitary crystals, rosettes, clusters and raphids.
• Example, cystoliths, are calcium carbonate clusters in cells.

Fats

• Lipids (fats and oils) are widely distributed in plant cells.
• Fats function as protective substances in and on the cells walls.

Explore the fascinating fields of pharmacognosy and plant anatomy. Learn about the properties of natural medicines and the structure of plant cells and tissues. This quiz covers key concepts from traditional uses of plants to modern drug discovery.