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Chapter 1 Notes: Anatomy & Physiology Overview

1.1 Overview of Human Anatomy and Physiology

  • Quote for the Course: "There is no structure without a function, and no function without a structure".

  • Terminology:

    • Anatomy: science of structure; relationships revealed by dissection or imaging techniques.

    • Physiology: science of body functions; normal adult physiology described in the text (with some genetic variations).

  • Anatomy: Greek: anatomē (dissection); The study of structure and the relationships among structures.

    • Subdivisions: Surface anatomy; Gross anatomy; Systemic anatomy; Regional anatomy; Radiographic anatomy; Developmental anatomy; Embryology; Cytology; Pathological anatomy.

  • Physiology: Greek: physis (nature) + logos (study); The study of bodily function by analysis of roles of molecules, cells, tissues, organs, and organ systems.

    • Subdivisions: Cell physiology; Systems physiology; Pathophysiology; Exercise physiology; Neurophysiology; Endocrinology; Cardiovascular physiology; Immunophysiology; Respiratory physiology; Renal physiology; Reproductive physiology.

  • No organ system acts alone: interdependent. Critical for understanding healthy anatomy, physiology, pathophysiology, and medicine.

  • Why bother with terminology and chemistry and synthesis of concepts?

    • Clinical issues and the physical exam.

    • Communication with health care professionals and/or patients.

    • Understanding your own body.

  • Symptom vs Sign vs Physical Exam:

    • Symptom: patient’s perception of a change in normal bodily function; hard to measure.

    • Sign: physical manifestation of disease; observed through sight, hearing, touch.

    • Physical Exam: 5 components:

    • Inquiry (patient history)

    • Inspection (sight)

    • Palpation (touch)

    • Percussion (touch and hearing)

    • Auscultation (heart & lung; carotid bruits).

  • Vital Signs (body checks used in exams):

    • Body temperature

    • Pulse rate

    • Respiratory rate

    • Blood pressure

    • Weight (almost always part of the physical exam; some clinicians include it as a vital sign)

    • Height: a normal part of the physical exam, especially in children

    • Signs vary according to age, sex, and condition of the patient.

  • Clinical Application: Autopsy

    • A postmortem examination of the body and dissection of internal organs to confirm or determine the cause of death.

    • Autopsy supplies information relating to the deceased individual.

  • Clinical Application: Medical Imaging

    • A specialized branch of anatomy and physiology essential for diagnosing disorders.

    • Radiography (x-rays).

    • Medical imaging techniques allow physicians to see inside the body to provide clues to abnormal anatomy and deviations from normal physiology to help diagnose disease.

  • Tests performed on the individual (visualize internal structures or processes; provide anatomical and/or physiological information):

    • Endoscopy (bronchoscopy, laparoscopy, cystoscopy, esophagoscopy, gastroscopy, colonoscopy, arthroscopy)

    • X-ray (standard and contrast; mammogram)

    • Angiography

    • CAT scan (CT scan)

    • Nuclear scan

    • PET

    • MRI

    • Ultrasound, Echocardiography

    • ECG, EEG, EMG

    • Pulmonary Function Test

    • Cytology

1.2 Biological Organization

  • Table 1.1: Levels of Organization — New properties emerge at each level.

    • Atoms: valence electrons determine reactivity.

    • Molecules: groups of atoms bonded in a three-dimensional shape.

    • Sub-Cellular Level / Cellular Level: cellular structures lead to basic functions.

    • Organelles: structures within cells that lead to cellular function.

    • Cells: basic unit of life; the human cell is eukaryotic and contains organelles.

    • Tissues: cells with similar functions; basic unit of life; e.g., smooth muscle tissue.

    • Organs: groups of tissues with similar functions.

    • Organ Systems: organs with similar functions.

    • Human Organisms: functional grouping of the lower-level components to make a living system.

  • Diagram/Concept: CHEMISTRY → Atoms → Molecules → Cells → Tissues → Organs → PHYSIOLOGY → CELL BIOLOGY → MOLECULAR BIOLOGY → ECOLOGY → Organ systems → Organisms → Populations of one species → Ecosystem → Biosphere.

  • OARRA (Organization, Acquisition, Response, Reproduction, Adaptation):

    • Organization: segregate internal and external environments.

    • Acquisition: movement; acquire material and energy (metabolism); excretion of waste.

    • Response: response and regulation.

    • Reproduction: growth and development; sexual reproduction.

    • Adaptation: homeostasis.

  • Human Organization (Levels from chemical to organism):
    1) Chemical level: atoms combine to form molecules.
    2) Cellular level: cells are made up of molecules.
    3) Tissue level: tissues consist of similar cells.
    4) Organ level: organs are made of different tissues.
    5) Organ system level: organ systems consist of different organs (e.g., Cardiovascular System).
    6) Organismal level: the human organism is made of many organ systems.

  • Organization leads to function (physiology):

    • Metabolism: sum of all chemical processes; includes catabolism and anabolism.

    • Responsiveness: ability to detect and respond to changes in external or internal environment.

    • Movement: motion of the whole body, organs, cells, or organelles.

    • Growth: increase in size and complexity via more/larger cells.

    • Differentiation: change from unspecialized to specialized state.

    • Reproduction: formation of new cells for growth/repair/replacement or production of a new individual.

1.3 Organ Systems

  • Integumentary system

    • Components: Cutaneous membrane; hair follicles; sweat glands; nails; sensory receptors.

    • Functions: Protect against environmental hazards; regulate body temperature; sensation of touch; production of Vitamin D.

  • Skeletal system

    • Components: Bones, cartilages, joints; bone marrow.

    • Functions: Support; protection; mineral storage; blood formation.

  • Muscular system

    • Components: Skeletal muscles; tendons; aponeuroses.

    • Functions: Locomotion; support; regulation of body temperature.

  • Nervous system

    • Components: Central nervous system; peripheral nervous system; special senses.

    • Functions: Fast response to stimuli; coordination of all other systems; described as "The Boss".

  • Endocrine system

    • Components: Pineal, pituitary, thyroid, parathyroid, adrenal glands; thymus, kidneys, pancreas, gonads, heart, digestive tract.

    • Functions: Regulates total body metabolism, growth, reproduction; mediates long-term changes in homeostasis; referred to as the other "Boss".

  • Cardiovascular system

    • Components: Heart; blood vessels; blood.

    • Function: Transportation of substances throughout the body.

  • Lymphatic system

    • Components: Lymphatic vessels; lymph nodes; spleen; thymus.

    • Functions: Return excess tissue fluid; part of the immune system.

  • Respiratory system

    • Components: Nasal cavities, paranasal sinuses, pharynx, larynx, trachea, bronchi; lungs.

    • Functions: Gas exchange; pH control.

  • Digestive system

    • Components: Mouth, pharynx, esophagus, stomach, small intestine, large intestine; salivary glands, liver, gallbladder, pancreas.

    • Functions: Process and digest food; eliminate waste; absorb nutrients; regulate nutrient content in blood (liver and pancreas).

  • Urinary system

    • Components: Kidneys; ureters; urinary bladder; urethra.

    • Functions: Elimination of waste; homeostasis in water balance; pH control.

  • Reproductive system

    • Components: Male: testes, epididymis, vas deferens, seminal vesicles, prostate, bulbourethral glands, urethra, penis. Female: ovaries, fallopian tubes, uterus, vagina, clitoris, labia; mammary glands.

    • Functions: Produce gametes and sex hormones.

1.4 Homeostasis

  • Definition and etymology: from Greek homoios meaning "like" or "similar"; maintaining a constant internal environment despite changing external conditions; organ systems interact to produce homeostasis.

  • Law of Mass Balance: gain of substance is offset by equal loss.

    • Total substance = intake + production – excretion - metabolism

  • Core concepts:

    • Structure and function are closely related (molecular interactions; compartmentalization).

    • Information flow coordinates body function.

    • Homeostasis maintains internal stability.

  • Process map (water balance example):

    • Water added to body fluids decreases their concentration.

    • Person seeks out and drinks water.

    • Thirst pathways stimulated.

    • Body fluids become more concentrated.

    • Internal receptors sense change in internal concentration.

    • Loses body water by evaporation.

    • (Note: flow illustrates organizational tools for relationships and processes; schematic diagram showing atoms, molecules, cells, tissues, organs; flow charts depict sequential processes.)

  • Internal vs external environments:

    • External environment of body’s cells is extracellular fluid (ECF): interstitial fluid, intercellular fluid, tissue fluid, plasma.

    • Internal environment is intracellular fluid (ICF).

    • Compartmentalization via plasma membrane.

  • Maintenance of the internal environment:

    • Fluids are kept in optimal ranges by homeostatic mechanisms; two principal fluid compartments: ECF and ICF.

  • Components of homeostatic control in feedback loops:

    • Sensory receptors (receptors): monitor changes and send input to a control center.

    • Set point: reference value (average) for the controlled variable; sensitivity determined by allowed deviations from the set point.

    • Integrating center (control center): sets the set point; evaluates input; generates output commands.

    • Effector: structure that responds to counteract the stimulus.

  • Feedback loops: information about the status of a controlled condition is continually monitored and fed back to a central control region; a stimulus disrupts the controlled condition.

  • Interpreting components:

    • Receptor (Sensor)

    • Set point

    • Integrating Center (Control center)

    • Effector

  • Negative vs Positive feedback:

    • Negative feedback: the effector’s response reverses the original stimulus; stabilizes the variable.

    • Positive feedback: the response amplifies the original stimulus; used in specific processes (e.g., labor).

  • Positive feedback example: labor (placental CRH, oxytocin, prostaglandins; increasing receptors and gap junctions in myometrium during labor).

  • Negative feedback examples: rise vs fall cases illustrate how sensor → integrating center → effector actions restore the set point.

  • Set Point concepts and antagonistic effectors:

    • Set Point = normal range.

    • Integrating center reacts to changes away from set point.

    • Antagonistic effectors oppose each other for fine control of range.

  • Homeostasis: quantitative measurement (e.g., glucose with insulin): insulin injected alters glucose trajectory over time.

  • Endocrine vs Nervous systems in control:

    • Endocrine: slower, longer-lasting signals via hormones; time scale seconds to hours.

    • Nervous: rapid signaling (neurons, nerves); milliseconds; often hardwired but modifiable.

  • Control types:

    • Local control: metabolites, paracrine hormones act locally.

    • Reflex control: long-distance pathway using nervous and/or endocrine systems; includes stimulus, sensor, input signal, integrating center, output signal, target, response; negative feedback stabilizes, positive feedback reinforces, and feedforward control anticipates change.

  • Homeostatic control summary:

    • Imbalances arise from external or internal disruptions.

    • The nervous and endocrine systems regulate homeostasis, sometimes together or independently.

    • CO2, O2, temperature, pH, blood pressure, etc., are controlled by feedback loops.

  • Disorders and disease:

    • Disorder: derangement or abnormality of function.

    • Disease: illness characterized by a recognizable set of signs and symptoms.

    • Local disease affects a part or region; systemic disease affects the whole body or multiple parts.

    • Signs: objective changes observed/measureable by clinician (fever, rash).

    • Symptoms: subjective changes reported by patient (headache, nausea).

    • Diagnosis: distinguishing one disease from another, usually after history and physical examination.

  • Examples of disorders/diseases:

    • Diabetes Type II; Cardiovascular, Nervous, Urinary involvement.

    • Anorexia nervosa; Osteoporosis.

  • BioFlix resource: Homeostasis – Regulating Blood Sugar (example case study).

1.5 Terminology

  • Purpose: anatomical position, body regions, planes, sections, and directional terms to enable clear diagnosis and communication.

  • Anatomical Position:

    • Standard observation/imaging reference: standing, legs together, feet on floor, hands at sides, palms facing forward.

    • Supine: lying down in anatomical position.

    • Prone: lying face down in anatomical position.

  • Anatomical Directions (reference frame is the subject, not the observer):

    • Superior / Inferior (cranial/caudal): toward head / toward feet.

    • Anterior (Ventral) / Posterior (Dorsal): toward front / toward back.

    • Left / Right: relative to the subject.

    • Rostral / Caudal (in the head region): toward the nose end or toward the tail end in neural terms.

    • Dorsal / Ventral (synonymous with posterior/anterior in many contexts).

  • Medial / Lateral / Intermediate:

    • Medial: toward the midline.

    • Lateral: away from the midline; outer side.

    • Intermediate: between a more medial and a more lateral structure.

  • Proximal / Distal; Superficial / Deep:

    • Proximal: closer to the origin of a body part or point of attachment.

    • Distal: farther from the origin of a body part or point of attachment.

    • Superficial (external) / Deep (internal): toward/away from the body surface.

  • Ipsilateral / Contralateral; Bilateral / Unilateral:

    • Ipsilateral: same side of the body.

    • Contralateral: opposite sides.

    • Bilateral: pertaining to two sides.

    • Unilateral: one side.

  • Head region terminology:

    • Rostral / Caudal; Dorsal / Ventral; Anterior / Posterior; Superior / Inferior.

    • Rationale: helps describe structures in relation to the brain and body axes.

  • Planes of section (perpendicular to each other):

    • Transverse (cross) plane: divides superior and inferior portions.

    • Sagittal plane (right and left): includes midsagittal (through midline) and parasagittal (unequal portions).

    • Frontal/Coronal plane: anterior and posterior portions.

    • Additional: Midsagittal plane is a special sagittal plane through the midline.

  • Planes of Section: Microscopy

    • Cross section; Longitudinal section; Oblique section.

    • These are different appearances of sections cut through a curved tube at different levels.

  • Sectional Anatomy and Diagnostic Imaging

    • Why learn sections and directions? Most modern diagnostic tests use computerized images; ability to locate sections is essential.

    • Serial Reconstruction: sequential CT scans can be reconstructed into a 3-D image (e.g., rib fractures).

  • Cephalic and regional terminology (examples):

    • Cephalon (head), Oris (mouth), Cranium (skull), Facies (face), Mentis (chin), Frons (forehead), Oculus (eye), Auris (ear), Bucca (cheek), Nasus (nose), Cervicis (neck).

    • Thoracis (thorax), Mamma (breast), Abdomen (abdomen), Umbilicus (navel), Pelvis (pelvic), Manus (hand), Digits (fingers), Pes (foot).

    • Anterior Landmarks: Axilla (armpit), Antecubitis (front of elbow), Brachium (arm), Antebrachium (forearm), Carpus (wrist), Pollex (thumb), Digital digits (fingers).

    • Posterior Landmarks: Dorsum (back), Lumbus (loins), Acromial (shoulder), Cephalon (head), Cervicis (neck), Olecranon (elbow back), etc.; more terms listed under upper and lower limbs.

  • Body Regions and Cavities

    • Ventral (anterior) and Dorsal (posterior) body cavities.

    • Thoracic cavity subdivides into: pleural cavities (right and left for lungs), mediastinum (trachea, esophagus, major vessels), pericardial cavity (heart).

    • Abdominopelvic cavity subdivides into: abdominal cavity (digestive organs, some urinary organs) and pelvic cavity (urinary bladder, reproductive organs, distal digestive organs).

    • Diaphragm separates thoracic and abdominal cavities.

    • Serous membranes line the cavities and cover viscera; serous fluid reduces friction between layers.

  • Serous membranes and related cavities

    • Pleura: serous membrane surrounding the lungs. Visceral pleura clings to the lung; parietal pleura lines chest wall.

    • Pericardium: serous membrane of the pericardial cavity; visceral pericardium covers the heart; parietal pericardium lines the chest wall.

    • Peritoneum: serous membrane of the abdominal cavity; visceral peritoneum covers abdominal viscera; parietal peritoneum lines abdominal wall.

  • Organs and regional anatomy

    • Organs: lungs, heart, thymus, trachea, esophagus, blood vessels (etc.)

    • Left and right pleural cavities; Mediastinum; Pericardial cavity; Heart; Serous membranes (pleura, pericardium).

    • Digestive, urinary, and reproductive systems: Peritoneal cavity; Peritoneum; Organs located within the peritoneal cavity.

  • Abdominopelvic quadrants

    • RUQ: right lobe of liver, gallbladder, right kidney, portions of stomach, small and large intestine.

    • LUQ: left lobe of liver, stomach, pancreas, left kidney, spleen, portions of large intestine.

    • RLQ: cecum, appendix, portions of small intestine, reproductive organs (right ovary in female, right spermatic cord in male), right ureter.

    • LLQ: small intestine, portions of large intestine, left ureter, reproductive organs (left ovary in female, left spermatic cord in male).

  • Nine regions (for precise location/orientation in surgical planning).

  • Clinical Applications: Autopsy and Medical Imaging

    • Autopsy: postmortem examination to confirm/determine cause of death; provides information about the deceased.

    • Medical Imaging: diagnostic tool to see inside the body and identify abnormal anatomy/physiology; includes radiography and other modalities.

  • Conventional Radiography (X-ray)

    • One burst of X-rays produces a 2-D image on film; good for bone (osteology); limited soft tissue resolution.

  • Computed Tomography (CT Scan)

    • Moving X-ray beam; cross-section image on monitor; better soft tissue detail; can build 3-D views with multiple scans.

  • Digital Subtraction Angiography (DSA)

    • Radiopaque material injected into vessels; before/after images compared by computer; images of vessels highlighted.

  • Dynamic Spatial Reconstruction (DSR)

    • 3-D reconstruction of organs; observes movement/volume in real time; used for cardiac/blood vessel studies.

  • Ultrasound (US)

    • High-frequency sound waves; safe, noninvasive; used for fetal ultrasound, abdominal/pelvic organs, heart, and blood flow.

  • Magnetic Resonance Imaging (MRI)

    • Body exposed to strong magnetic field; protons align; radiowave pulses generate images; great soft-tissue detail; cannot be used with metal in the body.

  • Positron Emission Tomography (PET)

    • Radioactively labeled substance emits positrons; gamma rays detected and used to form images.

  • Notes on imaging terms: many slides include specific examples and figures illustrating planes, sections, and organ relationships. When studying, pay attention to how different imaging modalities reveal different tissue contrasts and functional aspects.

  • Additional cross-cutting themes to remember:

    • The body is organized into hierarchical levels from atoms to the biosphere, with emergent properties at each level.

    • Homeostasis integrates nervous and endocrine control to maintain stable internal conditions, often via negative feedback loops; positive feedback is used in specific processes like labor.

    • Anatomical terminology (position, planes, directions, regions, and cavities) is essential for clear communication in clinical settings.

    • Knowledge of body planes and sectional anatomy underpins interpretation of modern medical imaging techniques (CT, MRI, US, etc.).