Foundations of Anatomy & Physiology: Key Concepts, Cell Structure, and Biomolecules

Physiology and Pathophysiology

Definitions and Scope

Physiology is the study of the normal functioning of living organisms and their component parts, including all chemical and physical processes. Pathophysiology examines how body functions are altered in a diseased state.

• Physiology: Focuses on atoms, molecules, cells, tissues, organs, organ systems, and organisms.

• Pathophysiology: Studies abnormal body functions in disease.

Scientific Approaches in Physiology

Teleological vs. Mechanistic Explanations

Physiological phenomena can be explained by their purpose (teleological) or by their underlying mechanisms (mechanistic).

• Teleological: Explains "why" a process occurs (e.g., why do red blood cells transport oxygen? Because cells need oxygen and red blood cells bring it to them).

• Mechanistic: Explains "how" a process occurs (e.g., how do red blood cells transport oxygen? Oxygen binds to hemoglobin molecules contained in red blood cells).

Homeostasis

Homeostasis is the maintenance of a relatively stable internal environment, regulated within a range of values.

• Importance: Essential for survival and proper function of cells and organs.

• Example: Regulation of body temperature, blood glucose levels.

Experimental Design Concepts

• Crossover Study: Individual is both the experimental subject and control.

• Placebo: An inactive substance used as a control in experiments.

• Hypothesis: A logical guess about how an event takes place.

• Theory: A model with substantial evidence from multiple investigations; may become a scientific theory.

• Meta-analysis: Combines data from multiple studies using statistical techniques to extract significant trends.

Variables in Experiments

• Dependent Variable: The variable measured; plotted on the vertical (Y) axis.

• Independent Variable: The variable altered; plotted on the horizontal (X) axis.

Biomolecules and Chemical Structure

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They are a major source of energy and structural components in cells.

• Monosaccharides: Simple sugars; building blocks of complex carbohydrates.

• Glycosylated Molecules: Sugar molecules attached to carbohydrates.

• Elements: Make up more than 90% of the body's mass: oxygen, carbon, hydrogen.

Proteins and Amino Acids

Proteins are polymers of amino acids, which contain a central carbon atom attached to a hydrogen atom, an amino group, a carboxyl group, and a unique side chain (R group).

• Essential Amino Acids: Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine.

Ions and pH

• Cations: Positively charged ions (e.g., sodium, potassium, calcium, hydrogen, magnesium).

• Anions: Negatively charged ions (e.g., chloride, bicarbonate, phosphate, sulfate).

• pH Scale: Measures concentration of free hydrogen ions; indicates acidity or basicity.

Structure and Derivation of Fatty Acids

Fatty acids consist of a carboxylic acid group and a hydrocarbon tail.

• Saturated Fatty Acids: No double bonds.

• Monounsaturated Fatty Acids: One double bond.

• Polyunsaturated Fatty Acids: Two or more double bonds.

ATP (Adenosine Triphosphate)

ATP is the primary energy carrier in cells, produced mainly in mitochondria.

• Function: Provides energy for cellular processes.

Endocrine Glands

Endocrine glands secrete hormones directly into the bloodstream.

• Major Glands: Pancreas, thyroid, gonads, pituitary gland.

Apoptosis

Apoptosis is programmed cell death, a normal event in the life of an organism that removes unneeded cells.

Cell Structure and Function

Cell Organelles and Their Functions

Cells contain specialized structures called organelles, each with distinct functions.

Organelle	Main Function
Phospholipid Bilayer	Primary component of biological membranes; hydrophilic polar head and hydrophobic fatty acid tail
Nucleus	Cell's control center; contains genes and directs synthesis of RNA for ribosomes
Endoplasmic Reticulum (ER)	Interconnected membrane tubes; rough ER synthesizes proteins, smooth ER synthesizes fatty acids, steroids, and lipids
Golgi Complex	Series of hollow curved sacs; modifies, sorts, and packages proteins
Centrioles	Direct DNA movement during cell division
Ribosomes	Dense granules of RNA and protein; manufacture proteins under direction of cell's DNA
Mitochondria	Generate most of cell's ATP
Lysosomes	Digestive system of the cell; contain enzymes to break down bacteria or old organelles
Peroxisomes	Storage vesicles; degrade long-chain fatty acids and potentially toxic foreign molecules
Cytoskeleton	Provides cell shape, internal organization, intracellular transport, and movement

Cell Junctions and Tissue Types

Types of Cell Junctions

Cell junctions are specialized structures that connect cells and facilitate communication and adhesion.

• Communicating Junctions: Allow direct cell-to-cell communication (gap junctions).

• Occluding Junctions: Block movement of material between cells (tight junctions).

• Anchoring Junctions: Hold cells to one another and to the extracellular matrix (adherens junction, desmosome, focal adhesion, hemidesmosome).

Primary Tissue Types

The human body is composed of four primary tissue types, each with specialized functions.

• Epithelial Tissue: Covers body surfaces and lines cavities.

• Connective Tissue: Provides support and structure.

• Muscle Tissue: Enables movement.

• Nerve Tissue: Transmits electrical signals.

Additional info:

• Some content was expanded for clarity and completeness, such as the functions of organelles and the definitions of tissue types.

• Examples and applications were added to support understanding of key concepts.