Human Digestive System

• The digestive system's structure is directly related to its function of breaking down food.

Human Digestive System

• The mouth is the entry point for food, where mechanical digestion begins.
• The pharynx is a passageway for both food and air.
• The esophagus transports food from the pharynx to the stomach.
• The stomach is an organ that churns food and mixes it with gastric juices.
• The small intestine is the primary site of nutrient absorption.
• The large intestine absorbs water and forms feces.
• The rectum stores feces until elimination through the anus.

Accessory Organs and Glands

• The liver produces bile, which aids in fat digestion.
• The gallbladder stores and concentrates bile.
• The pancreas produces enzymes that digest carbohydrates, proteins, and fats.
• Bile is a fluid that emulsifies fats, breaking them into smaller droplets.
• Emulsification is the process of breaking down fats into smaller droplets for easier digestion.
• Enzymes are proteins that catalyze chemical reactions, including digestion.
• Ingestion is the act of taking food into the body.
• Chyme is the partially digested food that leaves the stomach.

Physical and Mechanical Digestion

• Physical digestion involves breaking food into smaller pieces without changing its chemical composition.
• Mechanical digestion is the physical breakdown of food, such as chewing.
• Feeding is the process of obtaining food.
• Digest is to break down food into smaller molecules.
• Teeth are used for mechanical digestion, breaking food into smaller pieces.
• The tongue assists in chewing and swallowing.
• Gastric juice is a fluid secreted by the stomach that contains enzymes and acid to aid in digestion.

Cell Cycle

• The cell cycle is a repeating series of growth, DNA replication, and division.
• Prophase is the first stage of mitosis, during which the chromosomes condense.
• Metaphase is the stage where chromosomes align in the middle of the cell.
• Anaphase is the stage where sister chromatids separate and move to opposite poles.
• Telophase is the final stage of mitosis, where the cell divides into two daughter cells.
• Cytokinesis is the division of the cytoplasm, resulting in two separate cells.

Phases and Stages

• Interphase is the period of the cell cycle between cell divisions.
• G1 phase is the first growth phase, where the cell increases in size and synthesizes proteins.
• S phase is the synthesis phase, where DNA replication occurs.
• G2 phase is the second growth phase, where the cell prepares for division.

Cell Division

• Mitosis: A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.
• Meiosis: A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Diploid and Haploid

• Diploid cells contain two sets of chromosomes.
• Haploid cells contain one set of chromosomes.

Cellular Reproduction and Genetics

• Cellular reproduction involves the creation of new cells from existing cells.
• Genetics is the study of heredity and the variation of inherited characteristics.

Species

• Species are a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
• Defining characteristics of species include morphological, physiological, biochemical, ecological, and genetic characteristics.
• Several types of species concepts exist, including biological, morphological, ecological, and phylogenetic.

Taxonomy

• Taxonomy is the science of classifying and naming organisms.
• Aristotle made early contributions to taxonomy.
• Carolus Linnaeus developed the binomial nomenclature system of classification.
• The hierarchical structure of taxonomy includes domain, kingdom, phylum, class, order, family, genus, and species.

Bacteria Domain

• Bacteria Domain: Kingdom Archaebacteria: Consists of single-celled organisms lacking cell nuclei and are classified as prokaryotes.
• Bacteria Domain: Kingdom Eubacteria: A domain made up of prokaryotes that usually have a cell wall and reproduce by cell division.