Cell Physiology Lecture 1

Physiology

• Physiology is the branch of biology that deals with the functions and activities of life or living matter and the physical and chemical phenomena involved.
• Human physiology is the science that explains the specific characteristics and mechanisms of the human body that make it a living being.

Levels of Organization

• Chemical level: Includes atoms, ions, and molecules necessary for life.
• Cellular level: A cell is the smallest independently functioning unit of a living organism, with many different types of cells (e.g., muscle, nerve, blood, etc.).
• Tissue level: A tissue is a group of many similar cells that work together to perform a specific function.
• Organ level: An organ is an anatomically distinct structure of the body composed of two or more tissue types, performing one or more specific physiological functions.
• System level: An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body, with 11 major systems in the human body.

Cell Physiology

• The basic living unit of the body is the cell.
• Cells are the building blocks of the body, providing structure for the body’s tissues and organs, ingesting nutrients and converting them to energy, and performing specialized functions.
• A cell is composed of three major parts: Nucleus, Cytoplasm, and Cell membrane.
• Protoplasm, the collective substance of the cell, is composed mainly of five basic substances: Water, electrolytes, proteins, lipids, and carbohydrates.

Protoplasm Components

• Water: 70% to 85% of the cell's composition.
• Electrolytes: Important ions in the cell include potassium, magnesium, phosphate, sulfate, bicarbonate, sodium, chloride, and calcium.
• Proteins: 10% to 20% of the cell mass, divided into structural and functional proteins.
• Lipids: 2% of the cell mass, mainly phospholipids and cholesterol, forming the cell membrane and intracellular membrane barriers.
• Carbohydrates: 1% to 3% of the cell mass, playing a major role in cell nutrition and structural functions.

Cell Structure

• Nucleus: The control center for the cell, responsible for transmitting and expressing genetic information encoded in DNA.
• Nucleolus: The site of synthesis of ribosomal RNA (rRNA) within the nucleus.

Specialized Cells

• Blood cells: Three main types - Red blood cells (erythrocytes), White blood cells (leukocytes), and Platelets (thrombocytes).
• Red blood cells: Collect oxygen in the lungs and deliver it to body tissues through gas exchange by simple diffusion.
• White blood cells: Help the body fight infectious disease and foreign objects in the immune system.
• Platelets: Bind together to prevent and stop bleeding when they recognize damaged blood vessels.