Introduction to Cell Physiology

Chemotherapeutic Agents

• Alter cellular function or disrupt cellular integrity, causing cell death
• Prevent cellular reproduction, eventually leading to cell death

Chemotherapeutic Drugs

• Destroy organisms that invade the body
  • Bacteria, viruses, parasites, protozoa, fungi
• Destroy abnormal cells within the body
  • Neoplasms and cancers

Parts of a Human Cell

• Nucleus
• Cell membrane
• Cytoplasm

Structure of a Cell

Cell Nucleus

• Contains genetic material
  • Necessary for cell reproduction
  • Regulates cellular production of proteins
• Each cell is “programmed” by the genes for the production of specific proteins
  • Allows the cell to carry out its function
  • Maintains cell homeostasis or stability
  • Promotes cell division

Cell Membrane

• Surrounds the cell
• Separates the intracellular fluid from the extracellular fluid
• Essential for cellular integrity

Structure of a Lipid Cell Membrane

Organelles of the Cytoplasm

• Mitochondria
• Endoplasmic reticulum
• Free ribosomes
• Golgi apparatus
• Lysosomes

Components of Cell Membrane

• Cell membrane is made up of lipids and proteins
• Several lipids make up the cell membrane
  • Phospholipids
  • Glycolipids
  • Cholesterol
• Lipid layer provides a barrier for the cell and maintains homeostasis of the cell

Receptor Sites

• Found on the cell membrane
• Specific receptor sites allow interaction with various chemicals

Identifying Markers

• Surface antigens
• Important in the role of cellular immunity
• Histocompatibility proteins allow for self-identification
• The body’s immune system recognizes these proteins and acts to protect self-cells and to destroy non–self-cells

Channels

• Channels or pores allow for the passage of substances into and out of the cell
• Some drugs are designed to affect certain channels within the cell

Cell Properties

• Endocytosis
  • Involves incorporation of material into the cell
  • Pinocytosis and phagocytosis occur
• Exocytosis
  • Allows a cell to move a substance to the cell membrane and secrete the substance outside the cell
  • Hormones, neurotransmitters, and enzymes are excreted into the body by this process

Homeostasis of the Cell

• Passive transport
  • Happens without the expenditure of energy and can occur across any semipermeable membrane
  • Occurs by diffusion, osmosis, and facilitated diffusion
• Active transport
  • Energy-requiring process
  • Movement of particular substances against a concentration gradient
  • Important in maintaining cell homeostasis

Passive Transport

• Diffusion
  • Does not require energy
  • The movement of solutes from a region of high concentration to a region of lower concentration across a concentration gradient
• Osmosis
  • Does not require energy
  • Movement of water from an area low in solutes to an area high in solutes

Phases of the Cell Cycle

• G₀ phase
  • Resting phase
• G₁ phase
  • Gathering phase
• S phase
  • Synthesizing phase
• G₂ phase
  • Last substances needed for division are collected and produced
• M phase
  • Actual cell division occurs, producing two identical daughter cells

Cell Cycle

Cell Physiology

• May alter the cell membrane, causing the cell to rupture and die
• May deprive the cell of certain nutrients, altering the proteins that the cell produces and interfering with normal cell functioning and cell division
• May affect the normal cells of patients to some extent