Anatomy and Physiology

The Study of Pathophysiology

• Physiology examines the functions of the body.
• Pathology studies the effects of diseases on the body.
• Pathophysiology studies the body's reaction to disease and dysfunction, including how diseases alter the body and affect overall health.
• Disease involves an interruption, cessation, or disorder of a body system or organ structure.
• Key aspects of disease include etiology, pathogenesis, morphologic changes, clinical manifestations, diagnosis, and clinical course.

Health

• According to the WHO (1948), health is a state of complete physical, mental, and social well-being, not just the absence of disease.
• Healthy People 2030 identifies 5 key environments impacting social determinants of health: economic stability, education, healthcare, neighborhood, and social context.
• Good health includes physical, social, and mental well-being.

Aspects of the Disease Process

• Etiology is the cause or factors behind a disease's onset, which can include biologic agents, physical forces, chemical agents, genetic inheritance, or nutritional imbalances.
• Many diseases originate from multiple factors, like cancer, heart disease, and diabetes.
• Risk factors include congenital conditions (present at birth) and acquired defects (caused after birth by injury, infection, or inadequate nutrition).
• Pathogenesis is how a disease evolves, including cellular and tissue events from initial contact with an etiologic agent to disease expression.
• Morphology refers to the fundamental structure of tissues and cells in relation to disease, and morphologic changes involve gross anatomic and microscopic changes characteristic of a disease.
• Histology studies the morphologic changes in the cells and extracellular matrix of body tissues.
• Lesions are pathologic or traumatic discontinuities of a body organ or tissue, often observed through imaging methods and biopsies.
• Clinical Manifestations includes the signs (objective, measurable findings) and symptoms (subjective feelings reported by the patient) of a disease which may vary among individuals.
• Syndrome is a compilation of signs and symptoms characteristic of a specific disease.
• Complications are adverse extensions of a disease or outcomes from treatment.
• Sequelae include lesions or impairments following a disease.

Diagnosis

• Diagnosis involves determining the nature or cause of a health problem, using patient history, physical examination, and diagnostic tests for validation.
• Validity is the degree to which a measurement tool accurately measures what it intends to measure
• Reliability is the consistency of repeated observations or tests.
• Sensitivity is the proportion of people with a disease who test positive.
• Specificity is the proportion of people without the disease who test negative.
• Predictive value indicates how well an observation or test predicts the presence of a disease.
• Positive predictive value is the proportion of true positive results in a population.
• Negative predictive value is the proportion of true negative observations in a population.

Clinical Process

• Acute diseases are usually severe and self-limiting (e.g., flu, COVID-19).
• Chronic diseases are long-term, requiring ongoing management to improve quality of life and limit symptoms (e.g., diabetes, asthma, which can have exacerbations and remissions).
• Subacute diseases are intermediate in severity and duration between acute and chronic.
• Preclinical stage is when the disease is not clinically evident but is destined to progress.
• Subclinical disease is not clinically apparent and is not destined to become clinically apparent.
• Clinical diseases are manifested by signs and symptoms.
• Carrier status refers to a person who harbors an organism without showing infection signs.

Epidemiology and Patterns of Disease

• Epidemiology studies disease occurrence in human populations, looking for patterns related to factors like age, race, diet, lifestyle, or location.
• Incidence is the number of new cases in a population at risk during a specific time.
• Prevalence measures the existing disease in a population at a given time.

Morbidity and Mortality

• Morbidity describes the effects of an illness has on a person's life.
• Mortality statistics provide data on the causes of death in a population.

Determination of Risk Factors

• Risk factors are conditions suspected of contributing to disease development.
• Cross-sectional studies compare disease prevalence between different groups.
• Case-control studies compare people with a specific outcome to those without it.
• Cohort studies observe a group of people sharing characteristics over time.

Preventing Disease

• Primary prevention aims to prevent disease by removing risk factors, such as through immunizations.
• Secondary prevention detects disease early through screenings when treatment can be more effective (e.g., PAP smears).
• Tertiary prevention involves interventions to prevent further deterioration and reduce complications once a disease is diagnosed.

Protoplasm

• Protoplasm, the intracellular fluid, comprises water (70-85%), proteins (10-20%), lipids (2-3%), carbohydrates (1%), and intracellular ions (K+, Mg2+, PO4-, SO4, HCO3-, Na+, Cl-, Ca2+).
• The two regions of protoplasm are karyoplasm/nucleoplasm (inside the nucleus) and cytoplasm (outside the nucleus).

The Nucleus

• The nucleus is the cell's control center, containing DNA, where its primary function is cellular division and genetic information control.
• It provides RNA for protein synthesis, including mRNA (messenger), rRNA (ribosomal), and tRNA (transfer).
• It is enclosed by a nuclear envelope with pores for molecular exchange.
• Osteoclasts have more than one nucleus

Cytoplasm and Organelles

• The cytoplasm is located outside the nucleus, containing cytosol (aqueous solution) and organelles.
• Organelles are suspended in the cytoplasm and perform various functions.
• Ribosomes are the sites of protein synthesis, composed of rRNA and proteins, located in the cytoplasm or attached to the rough ER.
• The endoplasmic reticulum (ER) consists of tubular channels for protein and lipid transport.
• Rough ER contains ribosomes for protein synthesis (e.g., digestive enzymes, insulin).
• Smooth ER lacks ribosomes, synthesizing lipids, as well as carrying out detoxification and calcium storage.
• The Golgi complex modifies, sorts, and packages proteins from the ER and produces vesicles for protein transport.
• Lysosomes digest worn-out cell parts and foreign materials and allow the cell to autodigest.
• Peroxisomes detoxify free radicals and degrade peroxides.
• Mitochondria are responsible for generating energy and producing ATP through cellular respiration.
• The Cytoskeleton is a network of microtubules, microfilaments, intermediate filaments, and thick filaments which controls cell shape and movement

Membranes

• The cell membrane separates intracellular components from the extracellular environment, allowing cells to form tissues and organs.
• Plasma membranes have a selective transport system with gates, channels, and pumps, influencing metabolic pathways.

Cell Membrane Components

• The lipid bilayer serves as a semipermeable barrier, composed of phospholipids with hydrophilic heads and hydrophobic tails.
• Integral proteins span the lipid bilayer, forming ion channels.
• Peripheral proteins are bound to one side of the membrane.
• Glycocalyx participates in cell-to-cell recognition and adhesion.

Cell Membrane Function

• The cell membrane provides receptors for hormones and other biologically active substances: neurotransmitters, antigens, lipoproteins, infectious agents, and drugs.
• It participates in electrical events, regulates cell growth and proliferation.
• Microtubules form from tubulin, which develop and maintain cell form, participate in intracellular transport, and contain cilia and flagella and centrioles and basal bodies.
• Microfilaments produce muscle contraction and support cell shape.
• Microfilaments can be thin, intermediate, thick myosin.

Cell Communication

• Cell communication is essential for maintaining homeostasis.
• Autocrine signaling affects a cell’s own activity.
• Paracrine signaling acts on nearby cells.
• Endocrine signaling uses hormones carried in the bloodstream.
• Synaptic signaling occurs in the nervous system.

Cell Receptors and Ligands

• Ion channel-linked receptors facilitate rapid synaptic signaling.
• G-protein-linked receptors act as on-off switches for signal transduction.
• Enzyme-linked receptors are receptors for protein hormones.
• Intracellular receptors allow ligands to move directly across the membrane.
• First messengers include neurotransmitters and hormones.
• Second messengers are intracellular mechanisms like protein kinases.

The Cell Cycle and Cell Division

• The main stages of the cell cycle include mitosis and interphase.
• Mitosis is the cell division stage, while interphase is the non-dividing phase.
• Mitotic cell division occurs in somatic cells.
• Meiosis occurs in gamete-producing cells.

Cell Metabolism and Energy Sources

• Energy metabolism converts fats, proteins, and carbohydrates into ATP.
• Catabolism breaks down nutrients to produce energy.
• Anabolism builds more complex molecules from simpler ones.
• Anaerobic glycolysis occurs in the cytoplasm.
• Aerobic pathways occur in the mitochondria.

Movement of Substances Across the Cell Membrane

• Passive transport does not require energy, including diffusion, facilitated diffusion, and osmosis.
• Active transport requires energy, including primary and secondary active transport (symport/cotransport and countertransport/antiport).
• Endocytosis involves cells engulfing materials.
• Phagocytosis is cell eating, involving engulfment and degradation of microorganisms.
• Exocytosis is the secretion of intracellular substances.

Membrane Potential

• Ion channels are integral proteins that allow ions to move across the membrane.
• Electrical potentials exist across membranes due to ion distribution.
• Resting membrane potential describes the voltage generated by ions diffusing across the cell membrane.
• Equilibrium potential is when no net movement of ions occurs due to balanced diffusion and electrical forces.

Organization of Cells into Tissues

• Similar cells organize into tissues, which then form organs.
• The four types of tissue are epithelial, connective, neural, and muscle.

Epithelial Tissue

• Epithelial tissue covers the body's outer surface, lines internal cavities, and forms glands.
• It has apical, lateral, and basal surfaces and is avascular.
• Types include squamous, cuboidal, columnar, simple, stratified, and pseudostratified.

Connective Tissue

• Connective tissue connects and supports various tissues.
• Types include connective tissue proper (loose, adipose, reticular, and dense) and specialized connective tissue (cartilage, bone, and blood cells).

Muscle Tissue

• Muscle tissue contracts to produce movement.
• It contains actin and myosin filaments.
• Types include cardiac, smooth (involuntary), and skeletal (voluntary).

Nervous Tissue

• Nervous tissues control body function and aid in sensing and moving.
• Cell types include neurons and neuroglial cells.

Cell Junctions and Cell-to-Cell Adhesion

• Tight junctions seal adjacent cell membranes together.
• Adhering junctions provide strong adhesion between cells.
• Gap junctions link the cytoplasm of adjacent cells.

Extracellular Matrix (ECM)

• Extracellular matrix is composed of glycosaminoglycans (GAGs) and fibrous proteins like collagen, elastin, fibronectin, and laminin in the basement membrane.
• ECM is secreted and organized into a supporting mesh, with varying amounts and types depending on tissue function.

Test your knowledge of human anatomy and physiology with this quiz! It covers epithelial, connective, and muscular tissues. Explore cells, junctions, and structural organization.