MT

ANPH 209 – Module 2

Levels of Structural Organization

  • The body is organized into six distinct, increasing levels of complexity from chemical building blocks to a complete organism:
    • Chemical level: atoms and molecules; atoms bond to form molecules (e.g., water, DNA). Essential life atoms include carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), calcium (Ca), and sulfur (S).
    • Cellular level: cells are the basic structural and functional units of an organism; many different kinds of cells exist (e.g., muscle, nerve, epithelial).
    • Tissue level: tissues are groups of similar cells and the surrounding extracellular materials that perform a specific function; four basic tissue types are:
    • Epithelial
    • Connective
    • Muscular
    • Nervous
    • Organ level: organs are structures composed of two or more tissue types that work together to carry out specific functions (e.g., heart, lungs, kidneys); stomach comprises multiple tissues and associated membranes.
    • Organ system level: systems are related organs with a common function; e.g., the Digestive system includes mouth, small and large intestines, liver, gallbladder, pancreas.
    • Organismal level: many organ systems work together to form a functioning human organism.
  • Figure reference: Levels of Structural Organization video (conceptual).
Chemical Level Details
  • Basic level components: atoms and molecules.
  • The smallest unit of matter: atoms.
  • Essential life atoms include: C, H, O, N, P, Ca, S.
  • Example molecule: Deoxyribonucleic acid (DNA).
Cellular Level Details
  • Cells: basic structural and functional units.
  • Examples of cell types: muscle cells, nerve cells, epithelial cells.
Tissue Level Details
  • Tissues: groups of cells and surrounding materials (extracellular matrix) that work to perform a function.
Organ Level Details
  • Organs: composed of two or more tissue types, with specific functions and recognizable shapes.
  • Examples: Heart, lungs, kidneys; stomach composed of serous membrane, smooth muscle, and epithelial layers for digestion.
System Level Details
  • System: related organs with a common function.
  • Example: Digestive system: breaks down and absorbs food; includes mouth, small/large intestines, liver, gallbladder, pancreas.
Basic Life Processes of a Living Human Organism
  • Distinguish living from non-living.
  • Six important life processes:
    • Movement
    • Respiration
    • Responsiveness (Sensitivity)
    • Growth
    • Reproduction
    • Metabolism
    • Differentiation

The Generalized Cell

  • Plasma membrane:
    • Forms the cell’s outer boundary; separates internal from external environments.
    • Is a selective barrier.
    • Plays a role in cellular communication.
  • Cytoplasm:
    • All cellular contents between the plasma membrane and the nucleus.
    • Cytosol: fluid portion, mostly water.
    • Organelles: subcellular structures performing specific functions.
    • Major organelles (from Fig. 3.13 prototype cell):
    • Nucleus, nuclear envelope, nuclear pore, chromatin (DNA), nucleolus
    • Rough endoplasmic reticulum (RER) with ribosomes
    • Smooth endoplasmic reticulum (SER)
    • Golgi apparatus with Golgi vesicles
    • Mitochondria
    • Lysosome, peroxisome, secretory vesicle
    • Vesicles, vacuoles
    • Cytoskeleton components: microtubules, intermediate filaments, microfilaments
    • Centrosome/centriole (animal cells)
    • Ribosomes (free and on RER)
    • Plasma membrane (phospholipid bilayer with embedded proteins and cholesterol)
  • Prototypical human cell note: not representative of any one cell but shows primary organelles and internal structures.
Nuclear and Cytoplasmic Components
  • Nucleus: houses genetic material (DNA) organized as chromatin; contains nucleolus for ribosome synthesis.
  • Nuclear envelope: regulates movement of materials into and out of nucleus; contains nuclear pores.
  • Chromatin: DNA complex with proteins; becomes chromosomes during division.
  • Cytoskeleton: provides shape, support, and movement for cell parts; includes microtubules, microfilaments, and intermediate filaments.
  • Organelles:
    • Ribosomes: sites of protein synthesis; may be free or bound to RER.
    • Endoplasmic reticulum (RER and SER): synthesis of proteins, membranes, and lipids; RER has ribosomes; SER handles lipid synthesis and detoxification.
    • Golgi apparatus: modifies, sorts, and packages proteins and lipids for secretion or delivery to destinations.
    • Mitochondria: produce cellular energy via aerobic metabolism.
    • Lysosomes: digestive enzymes; digest food and worn-out organelles.
    • Peroxisomes: contain enzymes for detoxification and lipid metabolism.
    • Vesicles and vacuoles: transport and storage; secretory vesicles release substances outside the cell.
    • Centrioles (animal cells): organize mitotic spindle during cell division.
Cell Membrane Functions
  • Isolation: isolates cell contents; regulates material movement; enables communication with other cells.
  • Exchange regulation: controls substance exchange across the membrane.
  • Cellular communication: permits signaling between cells.
  • Cell attachments: facilitates attachments within and between cells.
  • Biochemical regulation: participates in many reactions at the membrane.

Cell Membrane Structure and Components

  • Phospholipid bilayer: two layers with hydrophobic tails and hydrophilic heads.
    • Polar phosphate head is hydrophilic; non-polar fatty acid tail is hydrophobic.
    • Unsaturated fatty acids introduce kinks in tails, affecting membrane fluidity.
  • Proteins:
    • Integral membrane proteins: span the membrane.
    • Peripheral membrane proteins: associated with the membrane surface.
    • Channel proteins and carrier proteins: regulate transport of substances.
  • Lipids and carbohydrates:
    • Cholesterol helps modulate membrane fluidity and stability.
    • Glycoproteins and glycolipids contribute to cell recognition and signaling.
  • Concept: the cell membrane is a dynamic phospholipid bilayer with a mosaic of proteins and other molecules embedded in or attached to it.
Membrane Transport and Permeability
  • Membrane permeability: selectively permeable; some substances cross easily, others require assistance.
  • Transmembrane transport proteins: channels and transporters facilitate entrance of substrates (e.g., glucose, ions).
  • Osmosis and solute movement:
    • Isotonic: solutions with equal solute concentrations; no net water movement.
    • Hypertonic: higher solute concentration outside; water moves out of the cell.
    • Hypotonic: lower solute concentration outside; water moves into the cell.
Passive vs Active Transport
  • Passive transport: substances move across membranes without cellular energy; rely on kinetic energy.
    • Simple diffusion: diffusion of lipid-soluble or very small molecules across the phospholipid bilayer.
    • Facilitated diffusion: diffusion of ions or water-soluble molecules via channel or carrier proteins; channels are less selective; carriers are more selective.
    • Osmosis: diffusion of water across a selectively permeable membrane.
  • Active transport: requires cellular energy (usually via ATP) to move substances against their concentration gradients.
  • Endocytosis and Exocytosis: energy-requiring bulk transport mechanisms.
    • Endocytosis: engulfing extracellular material via vesicle formation; includes Phagocytosis (large particles), Pinocytosis (fluid), and Receptor-mediated endocytosis (highly selective).
    • Exocytosis: release of materials from the cell via vesicle fusion with the plasma membrane.
Facilitated Diffusion (Figure Reference)
  • Channel proteins: less selective, discriminate by size/charge to some extent.
  • Carrier proteins: highly selective, often transporting a single molecule type.
Sodium-Potassium Pump (Na+/K+-ATPase)
  • Location: many cell membranes.
  • Mechanism: uses ATP to move Na+ and K+ in opposite directions, against their gradients.
  • In one cycle:
    • Three Na+ ions are extruded from the cell.
    • Two K+ ions are imported into the cell.
  • Overall effect: maintains the resting membrane potential and cell volume.
  • Representation:
    • 3\ Na^+ \text{ (out)} \quad\text{and}\quad 2\ K^+ \text{ (in)}
  • Powered by ATP hydrolysis: \text{ATP} \rightarrow \text{ADP} + P_i
Endocytosis Forms (Figure 3.10)
  • Phagocytosis: non-selective uptake of large particles; forms a vacuole.
  • Pinocytosis: uptake of fluids and dissolved substances in vesicles.
  • Receptor-mediated endocytosis: highly selective uptake triggered by ligand binding to receptors on the cell surface; ligands are internalized in coated vesicles.

Body Organization: Positions, Planes, and Cavities

  • Anatomical position: body upright, facing observer; head and eyes forward; feet flat and forward; upper limbs at sides; palms forward.
  • Terms for non-upright positions:
    • Prone: body lying face down.
    • Supine: body lying face up.
Body Planes and Sections
  • Planes and sections provide reference for anatomical description and are used to describe real or imagined cuts of the body or organs, commonly aiding in locating structures and discussing cross-sections.
  • Sagittal plane: vertical plane dividing body into right and left sides.
    • Midsagittal (median) plane: divides body into equal right and left halves.
    • Parasagittal plane: divides body into unequal right and left portions.
  • Frontal (coronal) plane: divides body into anterior (front) and posterior (back) portions.
  • Transverse (horizontal) plane: divides body into superior (top) and inferior (bottom) portions.
  • Oblique plane: passes at an angle between transverse and sagittal or frontal planes.
Regions, Planes, and Directional Terms
  • Directional terms pair in opposites to describe position relative to another structure:
    • Superior (cephalic) vs. Inferior (caudal)
    • Anterior (ventral) vs. Posterior (dorsal)
    • Medial vs. Lateral
    • Proximal vs. Distal
    • Superficial vs. Deep
    • Ipsilateral vs. Contralateral
  • Note: In humans, anterior = ventral and posterior = dorsal; in four-legged animals, terms are relative to the belly and back respectively.
Body Cavities and Membranes
  • Cavities provide protection, organization, and separation of organs:
    • Dorsal cavity: contains cranial cavity and vertebral (spinal) canal; lined by meninges.
    • Ventral cavity: contains thoracic and abdominopelvic cavities; lines are serous membranes.
  • Meninges: layers that line the cranial cavity and vertebral canal.
Dorsal vs Ventral Cavities (Overview)
  • Dorsal body cavity comprises:
    • Cranial cavity (brain)
    • Vertebral canal (spinal cord)
  • Ventral cavity comprises:
    • Thoracic cavity (within the rib cage)
    • Abdominopelvic cavity (below the thorax)
  • The thoracic cavity contains:
    • Mediastinum (central compartment containing the heart and major vessels)
    • Pleural cavities (surrounding each lung)
    • Pericardial cavity (surrounding the heart)
  • The abdominal cavity contains digestive organs; the pelvic cavity contains urinary bladder and reproductive organs.
  • The diaphragm separates thoracic from abdominopelvic cavities.
Serous Membranes
  • Serous membranes line both the walls of the cavities and the surfaces of the viscera within these cavities.
  • Key layers:
    • Parietal layer: lines the cavity walls.
    • Visceral layer: covers the visceral organs.
  • Specific serous membranes:
    • Pleura: lines pleural cavities around the lungs; visceral pleura covers lungs; parietal pleura lines chest wall.
    • Pericardium: lines heart-containing cavity; visceral pericardium covers heart; parietal pericardium lines chest wall.
    • Peritoneum: lines abdominal cavity; visceral peritoneum covers abdominal organs; parietal peritoneum lines abdominal wall.
Abdominopelvic Regions and Quadrants
  • The abdominopelvic cavity is divided into:
    • Nine regions (three across: right hypochondriac, epigastric, left hypochondriac; three middle: right lumbar, umbilical, left lumbar; three lower: right iliac, hypogastric, left iliac).
    • Four quadrants (RUQ, RLQ, LUQ, LLQ) created by two perpendicular lines: subcostal line (top) and transtubercular line (bottom), plus the midclavicular lines (vertical).
  • Specific organs within quadrants:
    • RUQ: liver and gallbladder
    • LUQ: stomach and spleen

Key Figures and Terms (Conceptual References)

  • Fig. 1.3 Levels of Structural Organization: visualizes the progression from chemical level to organism.
  • Fig. 3.2 & 3.3 Phospholipid structure and bilayer: highlights amphipathic nature and membrane fluidity determinants.
  • Fig. 3.4 Cell Membrane composition: illustrates phospholipid bilayer with proteins, cholesterol, glycoproteins, and glycolipids.
  • Fig. 3.6 Facilitated Diffusion: comparison of channel vs carrier proteins.
  • Fig. 1.12 Regions of the Human Body: visual regions mapping (anterior and posterior views).
  • Fig. 1.15 Dorsal and Ventral Body Cavities: dorsal vs ventral cavity organization.
  • Fig. 1.16 Abdominopelvic Regions and Quadrants: nine regions and four quadrants map.

Quick Glossary (Selected Terms)

  • Anatomical position: standard reference posture for describing body parts.
  • Prone: lying face down; Supine: lying face up.
  • Sagittal plane: divides into left and right; Midsagittal: equal halves; Parasagittal: unequal halves.
  • Frontal (coronal) plane: anterior and posterior sections.
  • Transverse (horizontal) plane: superior and inferior sections.
  • Oblique plane: angled plane between others.
  • Ipsilateral: on the same side; Contralateral: on opposite sides.
  • Proximal: closer to limb attachment; Distal: farther from attachment.
  • Superficial: closer to the surface; Deep: further from the surface.

Formulas and Notation Used in Transport and Membrane Concepts

  • Sodium-Potassium Pump cycle (Na+/K+-ATPase):
    • In one cycle: 3\ Na^+ \text{ are extruded} \quad\text{and}\quad 2\ K^+ \text{ are imported}
  • Powered by ATP hydrolysis: \text{ATP} \rightarrow \text{ADP} + P_i
  • Equilibrium concepts for isotonic/hypertonic/hypotonic solutions involve solute concentrations and water movement, described qualitatively above; quantitative osmolarity can be represented as the total solute particles per liter of solution (Osm) in practice.

Study Tips and Real-World Relevance

  • Understanding levels of organization helps connect molecular processes to organ-level function (e.g., how DNA (chemical level) affects cell function (cellular level), tissue types, organs, and whole-body systems).
  • Membrane transport concepts are foundational for physiology, pharmacology, and medical applications (e.g., how drugs enter cells via diffusion or transporters, and why osmosis matters in dehydration or edema).
  • Knowledge of body cavities, membranes, and regions provides a framework for clinical assessment, imaging interpretation, and surgical planning.
  • Ethical and practical implications: understanding human anatomy and physiology informs