Core Principles and Biological Molecules in Anatomy & Physiology

Core Principles of Anatomy & Physiology

Homeostasis

Homeostasis refers to the body's ability to maintain a stable internal environment despite changes in external conditions. This is essential for the proper functioning of cells and organs.

• Components of Homeostasis:

  • Receptor: Detects changes in the environment (stimuli).

  • Control Center: Processes information and determines the response (often the brain or endocrine glands).

  • Effector: Carries out the response to restore balance (e.g., muscles, glands).

• Example: Regulation of body temperature by sweating or shivering.

Feedback Mechanisms

Feedback mechanisms are processes that help maintain homeostasis by adjusting physiological processes.

• Negative Feedback: The most common mechanism; reverses a change to keep a variable within a normal range.

  • Example: Blood glucose regulation by insulin and glucagon.

• Positive Feedback: Enhances or amplifies a change; less common and usually associated with specific events.

  • Example: Blood clotting, childbirth contractions.

Structural-Functional Relationships

Structural-functional relationships describe how the form of a biological structure is related to its function.

• Example: The thin walls of alveoli in the lungs facilitate gas exchange.

• Additional info: This principle is fundamental in anatomy and physiology, as structure often determines the possible functions of tissues and organs.

Emergent Properties

Emergent properties are characteristics that arise at a higher level of organization that are not present at lower levels.

• Example: The heart can pump blood (an emergent property) only when all its cells and tissues work together.

Levels of Organization in Biological Systems

Biological systems are organized hierarchically from simplest to most complex.

• Chemical Level: Atoms and molecules

• Cellular Level: Cells and their organelles

• Tissue Level: Groups of similar cells

• Organ Level: Two or more tissue types

• Organ System Level: Organs working together

• Organismal Level: The whole organism

Anatomical Terms

Understanding anatomical terminology is essential for describing locations and positions in the body.

• Sectional Terms: Sagittal, coronal, transverse planes

• Positional Terms: Anterior, posterior, superior, inferior, medial, lateral, proximal, distal

• Example: The heart is medial to the lungs.

Body Cavities and Major Organs

The body contains several cavities that house major organs.

• Cranial Cavity: Contains the brain

• Thoracic Cavity: Contains the heart and lungs

• Abdominal Cavity: Contains digestive organs

• Pelvic Cavity: Contains reproductive organs, bladder

• Vertebral Cavity: Contains the spinal cord

Biological Molecules

Atoms and Their Structure

An atom is the smallest unit of matter that retains the properties of an element.

• Parts of an Atom:

  • Protons: Positively charged, found in the nucleus

  • Neutrons: No charge, found in the nucleus

  • Electrons: Negatively charged, orbit the nucleus

Kinetic and Potential Energy

Energy is the capacity to do work. In biological systems, energy exists in two main forms:

• Kinetic Energy: Energy of motion (e.g., movement of muscles)

• Potential Energy: Stored energy (e.g., energy stored in chemical bonds)

Metabolic Terms and Reactions

• Anabolism: Synthesis of complex molecules from simpler ones; requires energy (endergonic).

• Catabolism: Breakdown of complex molecules into simpler ones; releases energy (exergonic).

• Endergonic Reactions: Absorb energy ($\Delta G > 0$).

• Exergonic Reactions: Release energy ($\Delta G < 0$).

• Hydrolysis: Breaking down molecules by adding water.

• Dehydration Synthesis: Building molecules by removing water.

Chemical Bonds

Atoms combine to form molecules via chemical bonds. The three main types are:

• Ionic Bonds: Transfer of electrons from one atom to another.

• Covalent Bonds: Sharing of electrons between atoms.

• Hydrogen Bonds: Weak attractions between polar molecules.

Macromolecules: Carbohydrates, Lipids, Proteins

Macromolecule	General Structure & Building Blocks	Locations	Functions	Examples
Carbohydrates	Monosaccharides (simple sugars)	Blood, liver, muscle	Energy source, structural support	Glucose, glycogen
Lipids	Fatty acids, glycerol	Cell membranes, adipose tissue	Energy storage, insulation, membrane structure	Triglycerides, phospholipids
Proteins	Amino acids	Muscles, enzymes, cell structures	Catalysis, structure, transport	Hemoglobin, enzymes

Denaturation

Denaturation is the loss of a protein's native structure, resulting in loss of function.

• Causes: Heat, pH changes, chemicals

• Importance: Denatured enzymes cannot catalyze reactions effectively.

Enzymes

Enzymes are biological catalysts that speed up chemical reactions without being consumed.

• Role: Lower activation energy of reactions

• Example: Amylase breaks down starch into sugars

ATP (Adenosine Triphosphate)

ATP is the primary energy carrier in cells.

• Structure: Adenine, ribose, and three phosphate groups

• Source: Produced mainly by cellular respiration in mitochondria

• Function: Provides energy for cellular processes