exam review

Levels of Organization

  • Levels of Organization (Smallest → Largest)

    • 1. Chemical Level

    • Consists of atoms and molecules

    • Examples: water, proteins, DNA

    • 2. Cellular Level

    • Smallest living unit

    • Examples: Red Blood Cells (RBCs), neurons

    • 3. Tissue Level

    • Groups of similar cells

    • Four main types: epithelial, connective, muscle, nervous

    • 4. Organ Level

    • 2 or more tissues forming a structure

    • Examples: heart, stomach

    • 5. Organ System Level

    • Organs working together

    • 11 organ systems: skeletal, muscular, nervous, etc.

    • 6. Organism Level

    • The human body as a whole

Homeostasis

  • Definition: Maintaining internal balance despite external changes.

  • Keeps variables within normal ranges:

    • Temperature: ~37°C

    • pH: 7.35–7.45

    • Blood glucose: ~4–7 mmol/L

  • Achieved mainly through negative feedback loops

    • Examples: sweating vs shivering

Basic Anatomical Terminology

Body Positions

  • Anatomical Position: Standing upright, facing forward, arms at sides, palms forward.

  • Supine: Lying on back, face upward.

  • Prone: Lying on stomach, face downward.

  • Lateral: Lying on side (right or left)

Directional Terms

  • Anterior (ventral): Toward front.

  • Posterior (dorsal): Toward back.

  • Superior: Toward head.

  • Inferior: Toward feet.

  • Medial: Toward midline.

  • Lateral: Away from midline.

  • Proximal: Closer to point of attachment (limbs).

  • Distal: Farther from point of attachment.

  • Superficial: Toward surface.

  • Deep: Away from surface

Body Planes

  • Sagittal: Divides the body into left and right.

  • Frontal (coronal): Divides body into front and back.

  • Transverse: Divides body into upper and lower.

Body Cavities

  • Dorsal cavity: Contains cranial (brain) and vertebral (spinal cord).

  • Ventral cavity: Contains thoracic (heart and lungs) and abdominopelvic (digestive, urinary, reproductive organs).

  • Abdominal quadrants: RUQ, LUQ, RLQ, LLQ for clinical reference

Tissues

Four Main Tissue Types

  1. Epithelial Tissue

    • Function: Covers surfaces, lines cavities, forms glands.

    • Features:

      • Tightly packed cells with little extracellular space

      • Avascular (nutrients diffuse from underlying connective tissue)

      • Polarity (apical vs basal surfaces)

    • Specializations:

      • Microvilli → increase absorption (e.g., intestine)

      • Cilia → move substances (e.g., respiratory tract)

    • Classification:

      • By layers:

      • Simple (1 layer) → absorption/secretion

      • Stratified (multiple layers) → protection

      • Pseudostratified → looks layered, all cells touch basement membrane

      • By shape:

      • Squamous (flat)

      • Cuboidal (cube)

      • Columnar (tall)

    • Examples:

      • Simple squamous → diffusion (alveoli, capillaries)

      • Simple cuboidal → secretion (kidney tubules)

      • Simple columnar → absorption (digestive tract)

      • Pseudostratified ciliated columnar → mucus propulsion (respiratory tract)

      • Stratified squamous → protection (skin, mouth, esophagus)

      • Transitional → stretching (bladder)

  2. Connective Tissue

    • Function: Support, protection, transport, energy storage.

    • Features:

      • Fewer cells, abundant extracellular matrix (ECM) = ground substance + fibers.

    • Fibers:

      • Collagen (strength)

      • Elastic (stretch)

      • Reticular (support mesh)

    • Types:

      • Loose CT:

      • Areolar (cushions)

      • Adipose (stores fat)

      • Reticular (framework for organs)

      • Dense CT:

      • Regular (tendons, ligaments)

      • Irregular (dermis, organ capsules)

      • Cartilage:

      • Hyaline (ends of bones)

      • Fibrocartilage (intervertebral discs)

      • Elastic (ear)

      • Bone:

      • Compact (osteons)

      • Spongy (trabeculae, marrow)

      • Fluid CT:

      • Blood (transport)

      • Lymph (immune function)

  3. Muscle Tissue

    • Function: Movement, posture, heat.

    • Types:

      • Skeletal (voluntary, striated)

      • Cardiac (involuntary, striated, intercalated discs)

      • Smooth (involuntary, non-striated)

  4. Nervous Tissue

    • Function: Communication & control.

    • Components:

      • Neurons (signal transmission)

      • Neuroglia (support cells)

Epithelial Cell Shapes & Layers

  • Shapes:

    • Squamous (flat)

    • Cuboidal (cube)

    • Columnar (tall)

  • Layers:

    • Simple (1 layer)

    • Stratified (many layers)

    • Pseudostratified (appears layered)

    • Transitional (stretchable)

Nervous System

CNS vs PNS

  • CNS (Central Nervous System): Consists of the brain and spinal cord, functioning as the command center for processing and integration.

  • PNS (Peripheral Nervous System): Comprises nerves and ganglia outside the CNS, connecting the CNS to the body; includes somatic (voluntary) and autonomic (involuntary) divisions.

Roles of Neurons & Glial Cells

  • Neurons: Functional units that transmit electrical signals.

    • Parts:

    • Dendrites (receive signals)

    • Soma (cell body)

    • Axon (sends signals)

    • Synapse (communication point)

  • Glial Cells: Support, nourish, and protect neurons; include types such as oligodendrocytes (CNS) and Schwann cells (PNS) for myelin production.

Importance of Myelin Sheath

  • A fatty insulating layer around axons that speeds up signal transmission.

  • Produced by oligodendrocytes (CNS) and Schwann cells (PNS).

  • Gaps called Nodes of Ranvier allow rapid “jumping” of impulses (saltatory conduction).

Basic Nerve Impulse Pathway

  • Pathway: Dendrites → Soma → Axon → Synapse

  • Signals move in one direction for proper communication.

Disorders

  • Multiple Sclerosis (MS): Autoimmune attack on CNS myelin → results in demyelination and scar tissue; symptoms include vision problems and muscle weakness.

  • Stroke (Hemorrhage): Involves bleeding in the brain or spinal cord; symptoms include sudden severe headache, weakness, and loss of consciousness.

  • Peripheral Nerve Damage: Often caused by trauma or diabetes; affects sensation and movement.

Lab Links

  • CSF Analysis: Examines protein, glucose, cell counts, cultures, PCR for infections.

  • Lumbar Puncture (Spinal Tap): Used to collect CSF for testing.

  • Histology Stains:

    • Luxol Fast Blue (myelin)

    • Bielschowsky Silver (axons)

Skeletal System

Functions of Bone

  1. Support: Provides framework for the body.

  2. Protection:

    • Skull protects brain; ribs protect heart/lungs.

  3. Movement:

    • Bones act as levers for muscles.

  4. Mineral Storage:

    • Stores calcium & phosphate for nerve/muscle function.

  5. Blood Cell Production:

    • Red marrow involved in hematopoiesis; yellow marrow stores fat.

Basic Bone Structure

  • Compact Bone: Dense, strong outer layer.

  • Spongy Bone: Porous, lighter, found at the ends of long bones.

  • Long Bone Anatomy:

    • Diaphysis (shaft)

    • Epiphyses (ends)

    • Periosteum (outer covering)

    • Medullary cavity (contains yellow marrow)

Types of Bone Tissue

  • Compact Bone: Provides strength and support.

  • Spongy Bone: Houses red marrow for blood cell production.

Bone Marrow

  • Red Marrow: Located in spongy bone; produces red and white blood cells, and platelets.

  • Yellow Marrow: Found in medullary cavity; stores fat and can convert to red marrow during severe blood loss.

Joints: Classification & Movement

  • Synovial Joints: Freely movable (e.g., knee, shoulder).

  • Cartilaginous Joints: Limited movement (e.g., intervertebral discs).

  • Fibrous Joints: Little or no movement (e.g., skull sutures).

Common Disorders

  • Osteoporosis: Results in low bone density leading to brittle bones.

  • Arthritis: Joint inflammation; types include osteoarthritis, rheumatoid arthritis, and gout.

  • Fractures: Breaks in bones, diagnosed via imaging.

Lab Links

  • Calcium Levels: Monitors bone health.

  • ALP (Alkaline Phosphatase): An enzyme linked to bone formation; elevated levels indicate bone disease.

  • Synovial Fluid Analysis: Used for diagnosing arthritis or gout.

  • Bone Marrow Biopsy: For leukemia or other marrow disorders.

Muscular System

Three Types of Muscle Tissue

  1. Skeletal Muscle

    • Structure: Long, cylindrical fibers; multinucleated; striated (contains sarcomeres).

    • Control: Voluntary.

    • Location: Attached to bones.

    • Function: Responsible for movement, posture, heat generation, and control of openings (e.g., swallowing, urination).

  2. Cardiac Muscle

    • Structure: Short, branched fibers; 1–2 nuclei; striated; connected by intercalated discs.

    • Control: Involuntary.

    • Location: Found only in the heart.

    • Function: Produces rhythmic, coordinated contractions to pump blood.

  3. Smooth Muscle

    • Structure: Spindle-shaped fibers; single nucleus; non-striated (no sarcomeres).

    • Control: Involuntary.

    • Location: Walls of hollow organs (e.g., stomach, bladder, intestines), blood vessels, respiratory tract, eyes, and skin.

    • Function: Generates slow, sustained contractions for organ and vessel control.

Key Structural Differences

Feature

Skeletal

Cardiac

Smooth

Appearance

Striated

Striated

Non-striated

Cell Shape

Long fibers

Short, branched

Spindle-shaped

Nuclei

Many

1–2

Single

Control

Voluntary

Involuntary

Involuntary

Special Feature

Sarcomeres

Intercalated discs

Stretch-relax response

Contribution to Movement & Function

  • Skeletal Muscle: Produces fast, precise movements; maintains posture; generates heat.

  • Cardiac Muscle: Ensures rhythmic pumping for circulation.

  • Smooth Muscle: Maintains organ tone; regulates blood flow, digestion, and respiration.

Urinary System

Organs of the Urinary System

  • Kidneys: Filter blood, remove waste, regulate water and electrolytes, produce hormones (e.g., EPO, renin), and activate vitamin D.

  • Ureters: Muscular tubes that transport urine to the bladder via peristalsis.

  • Bladder: Hollow organ that stores urine (400–600 mL); lined with transitional epithelium for stretching.

  • Urethra: Tube for urine excretion; shorter in females (increasing UTI risk) and longer in males (also carries semen).

Nephron Processes

  1. Filtration:

    • Occurs at the glomerulus (a tuft of capillaries inside Bowman’s capsule).

    • Pushes water, ions, glucose, amino acids, and urea into filtrate; blood cells and proteins remain in blood vessels.

    • Driven by hydrostatic pressure against osmotic forces.

    • Produces approximately 180 L filtrate per day; only 1–2 L becomes urine.

  2. Reabsorption:

    • Reclaims water, sodium, glucose, amino acids, and bicarbonate.

    • Primary Tubule (PCT) does the majority of the work; Loop of Henle creates a salt gradient; Distal Convoluted Tubule (DCT) and collecting duct fine-tune under hormonal control (e.g., ADH, aldosterone, PTH).

  3. Secretion:

    • Adds wastes (creatinine, uric acid), drugs, toxins, H⁺, and K⁺ to the filtrate.

    • Primarily occurs in PCT, DCT, and collecting duct to maintain pH and electrolyte balance.

Glomerulus

  • Acts as a sieve with:

    • Fenestrated endothelium → allows fluid through, block cells.

    • Basement membrane → blocks large proteins.

    • Podocyte slits → serves as final filter.

  • Damage: Results in proteinuria (protein in urine).

Urine Epithelial Cells

  • Squamous: Large, flat; originates from urethra/external genitalia; often indicates contamination.

  • Transitional: Round/oval; derived from bladder/ureters; increased numbers suggest infection or irritation.

  • Renal Tubular: Small, round; sourced from nephron tubules; presence indicates kidney damage (e.g., acute tubular necrosis).

Common Disorders

  • UTIs: Infections of the urethra, bladder, or kidneys; lab findings may include WBCs, nitrites, and bacteria in urine.

  • Kidney Stones: Mineral deposits; symptoms include severe flank pain and hematuria; lab findings may reveal RBCs and crystals.

  • Glomerular Damage: Characterized by proteinuria and hematuria; tests may show elevated creatinine/BUN levels in blood.

Respiratory System

Major Organs

  • Upper Respiratory Tract:

    • Nasal Cavity: Filters, warms, and humidifies air.

    • Pharynx: Passage for air and food; divided into nasopharynx, oropharynx, laryngopharynx.

    • Larynx: Voice box; directs air into trachea and produces sound.

  • Lower Respiratory Tract:

    • Trachea: Windpipe supported by C-shaped cartilage rings.

    • Bronchi & Bronchioles: Branching airways leading to lungs.

    • Lungs: Right lung (3 lobes), left lung (2 lobes).

    • Alveoli: Tiny sacs for gas exchange; approximately 300 million per lung.

Processes

  • External Respiration: Gas exchange between alveoli and pulmonary capillaries; O₂ moves from alveoli to blood; CO₂ moves from blood to alveoli.

  • Internal Respiration: Gas exchange between systemic capillaries and tissues; O₂ moves from blood to cells; CO₂ moves from cells to blood.

Alveoli & Gas Exchange

  • Site of O₂ and CO₂ diffusion across the respiratory membrane (alveolar epithelium + capillary endothelium + basement membrane).

    • Type I Cells: Main surface for gas exchange.

    • Type II Cells: Secrete surfactant to prevent alveolar collapse.

    • Macrophages: Provide immune defense.

Common Disorders

  • Asthma: Bronchioles constrict due to inflammation, leading to wheezing and shortness of breath.

  • COPD: Chronic bronchitis and emphysema cause narrowed airways and loss of alveolar elasticity; often linked to smoking.

  • Pneumonia: Infection of alveoli causing fluid and pus accumulation, resulting in reduced gas exchange; symptoms include fever, cough, and chest pain.

Cardiovascular System

Structure of the Heart

  • Chambers:

    • Right Atrium: Receives deoxygenated blood from the body via superior and inferior vena cava.

    • Right Ventricle: Pumps blood to lungs through the pulmonary valve into the pulmonary arteries.

    • Left Atrium: Receives oxygenated blood from lungs via pulmonary veins.

    • Left Ventricle: Pumps blood to the body through the aortic valve into the aorta (thicker wall for systemic circulation).

  • Valves:

    • Tricuspid: Between right atrium and right ventricle.

    • Pulmonary: Between right ventricle and pulmonary artery.

    • Mitral (bicuspid): Between left atrium and left ventricle.

    • Aortic: Between left ventricle and aorta.

    • Function: Prevents backflow; “lub-dub” sound indicates valves closing.

  • Major Vessels:

    • Superior & Inferior Vena Cava: Return blood to right atrium.

    • Pulmonary Arteries: Carry blood to lungs.

    • Pulmonary Veins: Return oxygenated blood to left atrium.

    • Aorta: Largest artery, sends blood to body.

Electrical Conduction System

  • SA Node (Sinoatrial): Acts as the pacemaker, initiating the heartbeat.

  • AV Node (Atrioventricular): Delays the impulse to allow for atrial contraction before ventricles contract.

  • Bundle of His: Transmits the signal to ventricles.

  • Purkinje Fibers: Spread the impulse through ventricles for coordinated contraction.

Blood Vessels

  • Arteries: Thick muscular walls; carry blood away from the heart under high pressure.

  • Veins: Thinner walls; contain valves to prevent backflow; return blood to the heart under low pressure.

  • Capillaries: Microscopic; thin walls enable gas and nutrient exchange between blood and tissues.

Blood Components

  • RBCs (Erythrocytes):

    • Biconcave discs; lack nucleus; contain hemoglobin for O₂ transport; lifespan is approximately 120 days; produced in red bone marrow (stimulated by EPO).

  • WBCs (Leukocytes):

    • Defense cells; five types exist:

      • Granulocytes: Neutrophils, Eosinophils, Basophils.

      • Mononuclear (Agranulocytes): Monocytes, Lymphocytes.

  • Platelets (Thrombocytes):

    • Cell fragments essential for clotting (hemostasis).

  • Plasma:

    • Liquid portion comprising approximately 90% water; carries proteins, electrolytes, nutrients, hormones.

Circulation Pathways

  • Pulmonary Circuit: Right heart → lungs → left heart (responsible for gas exchange).

  • Systemic Circuit: Left heart → body tissues → right heart (for oxygen delivery and waste removal).

Common Disorders

  • Hypertension: Chronic high blood pressure that may damage vessels and organs.

  • Atherosclerosis: Buildup of plaque in arteries; narrows lumen and reduces blood flow.

  • Myocardial Infarction (Heart Attack): Blockage of coronary artery leading to tissue death; lab markers include elevated troponin and CK-MB.

Hematology Connections

  • Liver: Produces clotting factors (e.g., fibrinogen, prothrombin).

  • Spleen: Recycles old RBCs and WBCs; stores platelets; plays a role in immune surveillance.

ECG

What an ECG Represents

  • An Electrocardiogram (ECG) records the electrical activity of the heart over time.

  • It shows how impulses travel through the conduction system:

    • SA Node → AV Node → Bundle of His → Purkinje Fibers.

  • Each wave corresponds to a specific event:

    • P wave: atrial depolarization (atria contract).

    • QRS complex: ventricular depolarization (ventricles contract).

    • T wave: ventricular repolarization (ventricles relax).

Normal Pattern

  • Consistent rhythm with a regular P-QRS-T sequence.

  • Heart rate typically ranges from 60 to 100 beats per minute (bpm).

  • Normal would have no extra or missing waves; intervals remain within normal ranges.

Abnormal Patterns

  • Arrhythmias: Irregular rhythms due to conduction problems.

    • Examples:

    • Atrial fibrillation: chaotic atrial activity with no clear P waves.

    • Bradycardia: slow heart rate (below 60 bpm).

    • Tachycardia: fast heart rate (over 100 bpm).

    • Heart block: Delayed or absent conduction between the atria and ventricles.

  • Ischemic Changes: ST-segment elevation or depression often evident in myocardial infarction.

Digestive System

Major Organs of the GI Tract

  • Pathway: Mouth → Pharynx → Esophagus

    • Mouth: Involved in mechanical digestion (chewing) and chemical digestion (salivary amylase for carbohydrate breakdown).

    • Pharynx: Directs food to the esophagus; the epiglottis prevents entry into the airway.

    • Esophagus: Moves bolus to the stomach through peristalsis.

  • Stomach:

    • Churns food (mechanical digestion) and mixes it with gastric juice (chemical digestion).

    • HCl kills bacteria; pepsin begins protein digestion; produces intrinsic factor for vitamin B₁₂ absorption.

  • Small Intestine:

    • Duodenum: Mixes chyme with bile (from liver/gallbladder) and pancreatic enzymes; neutralizes acidity.

    • Jejunum: Primary site for nutrient absorption.

    • Ileum: Absorbs remaining nutrients and bile salts.

  • Large Intestine:

    • Absorbs water and electrolytes; forms feces; houses beneficial bacteria producing vitamin K and B vitamins.

  • Rectum & Anus:

    • Stores feces; controlled elimination via internal (involuntary) and external (voluntary) sphincters.

Accessory Organs

  • Liver:

    • Produces bile (emulsifies fats, neutralizes acid); processes nutrients; detoxifies; eliminates bilirubin.

    • Hematology Link: Synthesizes clotting factors, plasma proteins, and thrombopoietin; stores iron and vitamins.

  • Gallbladder:

    • Stores and concentrates bile; releases it into the duodenum when fats are present.

  • Pancreas:

    • Digestive Role: Secretes enzymes (amylase, lipase, proteases) and bicarbonate.

    • Endocrine Role: Produces insulin (lowers blood sugar) and glucagon (raises blood sugar).

Digestion Overview

  • Pathway: Mouth → Pharynx → Esophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus.

  • Physical Digestion: Occurs during chewing (mouth), churning (stomach), and segmentation (small intestine).

  • Chemical Digestion:

    • Mouth: Amylase for carbohydrates.

    • Stomach: HCl and pepsin for proteins.

    • Small Intestine: Bile for fats, pancreatic enzymes for carbohydrates, proteins, and fats, brush border enzymes.

  • Absorption:

    • Small intestine absorbs nutrients via villi and microvilli.

    • Large intestine reabsorbs water and electrolytes and forms feces.

Common Disorders

  • GERD: Acid reflux resulting from a weak lower esophageal sphincter; symptoms include heartburn and sour taste.

  • Ulcers: Open sores in the stomach or duodenum from H. pylori or excess acid; symptoms can include burning pain and possible bleeding.

  • Gallstones: Hardened deposits of bile in the gallbladder that can block ducts, resulting in pain after fatty meals.

  • Hepatitis: Inflammation of the liver caused by viral infection or toxic substances; symptoms include jaundice, fatigue, and dark urine.

Endocrine System

Major Endocrine Glands

  • Pituitary Gland: Known as the “Master gland”; responsible for controlling growth, metabolism, reproduction, and water balance.

  • Thyroid Gland: Produces thyroxine (T4) and T3 for metabolism; releases calcitonin to lower blood calcium levels.

  • Parathyroid Glands: Produce parathyroid hormone (PTH) which elevates blood calcium levels.

  • Adrenal Glands:

    • Cortex: Releases cortisol (affects stress response and metabolism) and aldosterone (regulates Na/water balance).

    • Medulla: Produces epinephrine and norepinephrine (involved in the fight-or-flight response).

  • Pancreas:

    • Produces insulin (lowers blood glucose by promoting uptake/storage).

    • Produces glucagon (raises blood glucose by promoting liver glycogen breakdown).

  • Gonads:

    • Ovaries: Produce eggs, estrogen, and progesterone.

    • Testes: Produce testosterone.

Pancreas Focus

  • Insulin: Decreases blood glucose levels by storing energy.

  • Glucagon: Increases blood glucose levels by releasing stored energy.

    • Both hormones work together to maintain blood sugar balance.

Other Important Hormones

  • Thyroxine (T4): Regulates metabolism.

  • Parathyroid Hormone (PTH): Raises blood calcium levels.

  • Cortisol: Involved in stress response, metabolism, and inflammation control.

  • ADH (Antidiuretic Hormone): Conserves water and increases blood pressure.

Common Disorders

  • Diabetes Mellitus: Results from an imbalance of insulin and glucagon leading to high blood glucose.

  • Thyroid Imbalances:

    • Hypothyroidism: Characterized by low T4 levels; symptoms include fatigue and weight gain; lab tests may show elevated TSH and low T4.

    • Hyperthyroidism: Characterized by high T4 levels; symptoms include weight loss and heat intolerance; lab tests may show low TSH and high T4.

Lab Relevance

  • TSH: Used to evaluate thyroid function (high in hypothyroidism, low in hyperthyroidism).

  • Glucose: Monitors blood sugar levels.

  • HbA1c (A1C): Reflects long-term glucose control.

  • Cortisol: Checks adrenal function (may be elevated in Cushing’s syndrome or low in Addison’s disease).

Reproductive System

Male Reproductive Organs

  • Testes: Produce sperm and testosterone.

  • Epididymis: Stores and matures sperm.

  • Vas deferens: Transports sperm to the urethra.

  • Seminal Vesicles: Add fructose-rich fluid to nourish sperm.

  • Prostate Gland: Secretes alkaline fluid to protect sperm in the acidic vaginal environment.

  • Penis: Delivers semen and serves as a passage for urine (not both simultaneously).

Female Reproductive Organs

  • Ovaries: Produce eggs, estrogen, and progesterone.

  • Fallopian Tubes: Transport eggs and are the site for fertilization.

  • Uterus: Supports fetal development; endometrium sheds during menstruation.

  • Cervix: Lower part of the uterus that produces mucus; dilates during childbirth.

  • Vagina: Passageway for menstrual flow, intercourse, and childbirth.

  • Vulva: External structures for protection and stimulation.

Key Hormones

  • FSH (Follicle-Stimulating Hormone): Stimulates sperm production and egg maturation.

  • LH (Luteinizing Hormone): Triggers ovulation and stimulates testosterone release.

  • Estrogen & Progesterone: Regulate the menstrual cycle and maintain pregnancy.

  • Testosterone: Promotes sperm production and male secondary sex characteristics.

Common Disorders

  • PCOS (Polycystic Ovary Syndrome): Hormonal imbalance leading to irregular periods, ovarian cysts, and infertility.

  • Endometriosis: Uterine lining tissue grows outside the uterus, resulting in pain and infertility.

  • Prostate Issues: Enlargement or cancer can cause urinary problems.

  • Infertility: May stem from low sperm count, blocked ducts, or hormonal imbalances.

Lab Links

  • hCG: Confirms pregnancy and is also used for cancer screening.

  • PSA: Screens for prostate cancer.

  • Pap Test: Detects cervical cell changes indicative of cancer or infection.

  • Hormone Panels: Measure FSH, LH, estrogen, progesterone, and testosterone for fertility and endocrine health.

Integumentary System

Three Layers of the Skin

  1. Epidermis

    • Outer protective layer composed of stratified squamous keratinized epithelium.

    • Contains keratinocytes (producing keratin for waterproofing) and melanocytes (producing melanin for UV protection).

    • Avascular; relies on dermis for nutrients.

    • Functions: Acts as a barrier against injury, microbes, and UV exposure; helps prevent dehydration.

  2. Dermis

    • Thick middle layer composed of dense connective tissue (includes collagen and elastin).

    • Contains blood vessels, nerves, hair follicles, sweat glands, and sebaceous glands.

    • Functions: Provides strength and elasticity; involved in sensation and thermoregulation.

  3. Subcutaneous (Hypodermis)

    • Deepest layer containing loose connective tissue and adipose tissue (fat).

    • Functions: Provides insulation, cushioning, energy storage, and anchors the skin to underlying structures.

Skin Glands

  • Sebaceous Glands:

    • Secrete sebum (oil) into hair follicles, lubricating skin/hair, and providing mild antibacterial action.

  • Eccrine Sweat Glands:

    • Most numerous, producing watery sweat for cooling and thermoregulation.

  • Apocrine Sweat Glands:

    • Located in the armpits and groin; secrete thicker sweat that bacteria break down, resulting in body odor.

Common Disorders

  • Eczema: An inflammatory condition characterized by dry, itchy patches.

  • Acne: Cl clogged follicles with oil, dead cells, and bacteria lead to inflammation.

  • Skin Cancers:

    • BCC (Basal Cell Carcinoma): Slow-growing with low metastatic risk.

    • SCC (Squamous Cell Carcinoma): More aggressive malignancy that can spread.

    • Melanoma: The most dangerous type, often appearing as an irregular dark patch; detection follows the ABCDE rule (Asymmetry, Border, Color, Diameter, Evolving).

  • Burns:

    • 1st-degree: Affects only the epidermis (red, painful).

    • 2nd-degree: Affects epidermis + part of dermis (blisters).

    • 3rd-degree: Involves full thickness (white or charred, nerve damage).

  • Bedsores: Pressure ulcers formed due to prolonged immobility.

Lab Relevance

  • Vitamin D Testing: The skin synthesizes vitamin D₃ through UV exposure.

  • Wound Swabs: Detect bacteria or fungi in infections.

  • Biopsies: Diagnose skin cancers or chronic illnesses.

  • Burns: Monitor fluid and electrolyte balance as well as protein levels.

Lymphatic and Immune System

Lymphatic System Basics

  • Lymph: Fluid collected from tissues (i.e., excess interstitial fluid), containing water, proteins, WBCs, debris, and pathogens.

  • Circulation:

    • Lymphatic system functions as a one-way drainage system (tissues → lymph vessels → nodes → ducts → subclavian veins).

    • Blood system operates as a closed loop (heart → arteries → tissues → veins → heart).

    • Movement of lymph occurs via skeletal muscle contractions, breathing, and valves (as there is no pump).

Major Organs

  • Lymph Nodes: Filter lymph and trap pathogens; house lymphocytes (immune cells).

  • Spleen: Filters blood, removes aged RBCs, and mounts immune responses.

  • Thymus: Site where T cells mature, teaching them the difference between “self” and “non-self.”

  • Tonsils: Trap pathogens coming from food and air.

  • MALT (Mucosa-Associated Lymphoid Tissue): Includes Peyer’s patches found in the intestines; protects mucosal surfaces.

Functions

  • Fluid Balance: Returns excess tissue fluid back to the bloodstream.

  • Filtration & Protection: Removes pathogens and abnormal cells.

  • Fat Absorption: Absorbs dietary fats and fat-soluble vitamins from the intestines.

Common Disorders

  • Lymphadenopathy: Swollen lymph nodes often resulting from infections, inflammation, or lymphoma.

  • Lymphangitis: Inflamed lymph vessels, often due to bacterial infection.

  • Lymphoma: Cancer of lymphocytes; includes Hodgkin and Non-Hodgkin types.

  • Mononucleosis: Viral infection (commonly from EBV) characterized by swollen lymph nodes, fatigue, and an enlarged spleen.

Immune System Key Concepts

  • Innate Immunity: Fast, non-specific immunity; includes skin, mucous membranes, inflammation, and natural killer (NK) cells.

  • Adaptive Immunity: Specific but slower initial response; involves B cells (creating antibodies) and T cells; generates memory cells for quicker responses upon reinfection.

WBC Functions

  • Neutrophils: First responders in infection; perform phagocytosis (cell eating).

  • Eosinophils: Combat parasites and are involved in allergic responses.

  • Basophils: Release histamine; play a role in allergic reactions.

  • Macrophages: Perform phagocytosis, cleaning up debris and activating the immune response.

  • Dendritic Cells: Present antigens to T cells, aiding in adaptive immunity activation.

  • NK Cells: Attack infected or cancerous cells without having been exposed previously.

Antibodies & Reactions

  • Classes of Antibodies:

    • IgG: Most prevalent; offers long-term immunity and can cross the placenta.

    • IgM: First antibody made during new infections; a strong agglutinator.

    • IgA: Found in mucus, tears, and saliva; protects mucosal surfaces.

    • IgE: Related to allergies; triggers histamine release.

    • IgD: Present on B cells; assists with their activation.

  • Antigen–Antibody Interactions: Include neutralization, agglutination, precipitation, and complement activation.

  • Affinity: The strength of one antigen–antibody bond.

  • Avidity: The overall strength of multiple antigen–antibody bonds.

Clinically Significant vs Insignificant Antibodies

  • Clinically Significant Antibodies:

    • Why they Matter: Can cause transfusion reactions or hemolytic disease of the newborn; must be identified and managed in laboratory settings.

    • Key Features: Typically of the IgG class, best reactive at body temperature (37°C), often requiring prior exposure (e.g., transfusion, pregnancy), detected during antibody screenings and cross-matching.

  • Clinically Insignificant Antibodies:

    • Why they Matter Less: Rarely cause clinical issues; may appear in tests but don’t compromise patient safety.

    • Key Features: Typically of the IgM class, reactive at room temperature or colder (approximately 4°C), often naturally occurring (form without prior exposure); examples include Lewis antibodies and cold agglutinins.

Quick Comparison Table

Feature

Clinically Significant

Clinically Insignificant

Immunoglobulin Class

IgG

IgM

Reaction Temperature

37°C (body temp)

Room temp or colder

Clinical Impact

Yes (risk of transfusion)

No major impact

Exposure Needed

Often yes

Often naturally occurring