BIOH 211: Comprehensive Study Guide for Blood, Heart, Circulatory, Lymphatic, Immune, Respiratory, Endocrine, Digestive, Metabolic, Urinary, Fluid/Electrolyte, and Reproductive Systems

Blood

General Functions and Composition of Blood

Blood is a specialized connective tissue with multiple vital functions, including transport, regulation, and protection. Its composition includes plasma and formed elements.

• Major Functions: Transport of gases, nutrients, hormones, and waste; regulation of pH, temperature, and fluid volume; protection against blood loss and infection.

• General Composition: Plasma (liquid matrix) and formed elements (cells and cell fragments).

• Plasma Components: Water, plasma proteins (albumin, globulins, fibrinogen), electrolytes, nutrients, gases, and waste products.

• Plasma Proteins: Albumin (osmotic pressure, transport), globulins (immunity, transport), fibrinogen (clotting); produced mainly by the liver.

• Leukocytes: Five types in order of prevalence: neutrophils, lymphocytes, monocytes, eosinophils, basophils. Each has distinct immune functions.

• Formed Elements: Erythrocytes (RBCs), leukocytes (WBCs), platelets (thrombocytes).

• Hematocrit: Percentage of blood volume occupied by RBCs. Calculated as: $\text{Hematocrit} = \frac{\text{Volume of RBCs}}{\text{Total Blood Volume}} \times 100$

• Factors Affecting Hematocrit: Dehydration, blood loss, anemia, polycythemia.

Hematopoiesis

Hematopoiesis is the process of blood cell formation, primarily occurring in the red bone marrow.

• Erythropoiesis: Formation of RBCs, regulated by erythropoietin (EPO) from the kidneys. Reticulocytes are immature RBCs.

• Hemoglobin: Oxygen-carrying protein in RBCs; broken down into heme (iron, bilirubin) and globin (amino acids).

• Anemia: Reduced oxygen-carrying capacity. Types: inadequate production (e.g., iron deficiency), hemolytic (destruction), hemorrhagic (blood loss).

• Leukopoiesis: Formation of WBCs, regulated by colony-stimulating factors.

• Thrombopoiesis: Formation of platelets from megakaryocytes, regulated by thrombopoietin.

Hemostasis

Hemostasis is the process that stops bleeding through three phases.

• Vascular Spasm: Vasoconstriction of damaged vessels; endothelial cells and serotonin involved.

• Platelet Plug Formation: Platelets adhere to exposed collagen, aggregate, and release chemicals.

• Coagulation: Intrinsic and extrinsic pathways activate factor X, leading to fibrin clot formation.

• Fibrinolysis: Breakdown of clot by plasmin (from plasminogen, activated by tPA).

• Aspirin: Inhibits platelet aggregation, reducing unwanted clots.

ABO and Rh Blood Typing

Blood typing is based on surface antigens and plasma antibodies.

• Agglutination: Clumping of RBCs due to antibody-antigen reaction.

• Surface Antigens/Antibodies: Type A (A antigen, anti-B antibody), Type B (B antigen, anti-A), Type AB (A and B antigens, no antibodies), Type O (no antigens, both antibodies).

• Rh Factor: Presence (+) or absence (−) of D antigen.

• Transfusion Compatibility: Determined by matching antigens and avoiding antibody reactions.

• Anti-Rh Antibodies: Develop after exposure; Rhogam prevents sensitization in Rh− mothers.

The Heart

Microscopic and Gross Anatomy

The heart is a muscular organ located in the thoracic cavity, protected by the pericardium.

• Pericardium: Fibrous and serous layers; serous fluid reduces friction.

• Heart Wall Layers: Epicardium (outer), myocardium (muscle), endocardium (inner).

• Atria vs. Ventricles: Atria receive blood; ventricles pump blood out.

• Coronary Circulation: Right/left coronary arteries → cardiac veins → coronary sinus → right atrium.

• Myocardium: Contains intercalated discs for synchronized contraction.

Blood Flow Through the Heart

• Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs → pulmonary veins → left atrium → bicuspid (mitral) valve → left ventricle → aortic valve → aorta.

Physiology of Cardiac Muscle Contraction

• Pacemaker Cells: Generate action potentials via ion channels (Na+, Ca2+, K+).

• Contractile Cells: Depolarize in response to action potentials; Ca2+ influx triggers contraction.

• Autonomic Innervation: Sympathetic increases rate/force; parasympathetic decreases rate.

Cardiac Cycle

• Cardiac Cycle: All events in one heartbeat (systole = contraction, diastole = relaxation).

• Phases: Ventricular filling, isovolumetric contraction, ventricular ejection, isovolumetric relaxation.

• Heart Sounds: S1 (AV valves close), S2 (semilunar valves close).

Regulation of Cardiac Output, Stroke Volume, and Heart Rate

• Cardiac Output (CO): Volume of blood pumped per minute. $\text{CO} = \text{HR} \times \text{SV}$

• Stroke Volume (SV): $\text{SV} = \text{EDV} - \text{ESV}$

• Ejection Fraction: $\text{Ejection Fraction} = \frac{\text{SV}}{\text{EDV}} \times 100$

• Venous Return, Preload, Afterload: Affect SV and CO.

• Frank-Starling Law: Increased preload increases SV.

• Inotropic/Chronotropic Agents: Affect contractility and heart rate.

Electrical Conduction System and ECG

• Conduction Pathway: SA node → AV node → AV bundle → bundle branches → Purkinje fibers.

• ECG Deflections: P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

• Arrhythmias: Abnormal rhythms; ectopic focus is an abnormal pacemaker site.

The Circulatory System

Blood Vessels

• Arteries: Carry blood away from the heart.

• Veins: Return blood to the heart.

• Capillaries: Exchange vessels; types include continuous, fenestrated, and sinusoidal.

• Tunics: Intima (endothelium), media (smooth muscle), externa (connective tissue).

• Vasoconstriction/Vasodilation: Narrowing/widening of vessels.

• Anastomosis: Connection between vessels (e.g., Circle of Willis).

Systemic and Pulmonary Circuits

• Systemic Circuit: Left heart → body → right heart.

• Pulmonary Circuit: Right heart → lungs → left heart.

• Portal System: Blood passes through two capillary beds (e.g., hepatic portal system).

Fetal vs. Postnatal Circulation

• Fetal Structures: Foramen ovale, ductus arteriosus, ductus venosus.

• Postnatal Remnants: Fossa ovalis, ligamentum arteriosum, ligamentum venosum.

Blood Pressure and Hemodynamics

• Blood Pressure (BP): Force exerted by blood on vessel walls.

• Peripheral Resistance (PR): Opposition to flow; mainly in arterioles.

• Key Equations: $\text{Flow} = \frac{\Delta P}{R}$; $\text{MAP} = \text{CO} \times \text{TPR}$

• Pulse Pressure (PP): $\text{PP} = \text{Systolic BP} - \text{Diastolic BP}$

• Mean Arterial Pressure (MAP): $\text{MAP} = \text{Diastolic BP} + \frac{1}{3}(\text{PP})$

• Capillary Exchange: Filtration and reabsorption driven by hydrostatic and osmotic pressures.

• Edema: Excess fluid in tissues; prevented by lymphatic drainage.

• Hormonal Regulation: ADH, angiotensin II, aldosterone, ANP, epinephrine, norepinephrine.

• Baroreceptor Reflex: Maintains BP homeostasis via autonomic adjustments.

Circulatory Shock

• Types: Hypovolemic (blood loss), vascular (vasodilation), cardiogenic (heart failure).

• Compensatory Mechanisms: Increased HR, vasoconstriction, fluid retention.

• EpiPen: Treats anaphylactic shock by vasoconstriction and bronchodilation.

Lymphatic and Immune Systems

Lymphatic System Structure and Function

• Structures: Lymphatic vessels, nodes, spleen, thymus, tonsils.

• Function: Returns interstitial fluid to blood, immune surveillance.

• Lymph Formation: From interstitial fluid; circulates via vessels to subclavian veins.

Immune Defenses

• Three Lines of Defense: Barriers (skin, mucosa), innate immunity (phagocytes, inflammation), adaptive immunity (lymphocytes).

• Key Terms: Diapedesis (WBC movement), chemotaxis (chemical attraction), opsonization (enhanced phagocytosis).

• Phagocytosis: Engulfment of pathogens by neutrophils, macrophages.

• Inflammation: Redness, heat, swelling, pain; benefits include containment and repair.

• Fever: Elevated body temperature; pyrogens reset hypothalamic set point.

• Antigen-Presenting Cells (APCs): Dendritic cells, macrophages, B cells.

• Cell Types: NK cells, dendritic cells, B cells, plasma cells, helper T cells, cytotoxic T cells, memory cells.

• Epitope: Specific antigen region recognized by immune cells.

• Antibody Classes: IgG, IgA, IgM, IgE, IgD; each with unique locations and functions.

• Primary vs. Secondary Response: Faster, stronger antibody production in secondary response.

• Cell-Mediated Immunity: Cytotoxic T cells destroy infected cells using perforin and granzymes.

• Active vs. Passive Immunity: Active (own antibodies), passive (received antibodies).

• Hypersensitivity: Type I (acute, e.g., allergy), Type IV (delayed, e.g., contact dermatitis).

Respiratory System

Structure and Function

• Pathway of Air: Nares → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.

• Histology: Varies by region; alveoli have thin walls for gas exchange.

• Pressures: Atmospheric, intrapulmonary, intrapleural, transpulmonary.

• Boyle's Law: $P_1V_1 = P_2V_2$; pressure inversely related to volume.

• Muscles: Diaphragm, intercostals (quiet); accessory muscles (forced).

• Dead Space: Air not involved in gas exchange.

• Alveolar Membrane: Three layers: alveolar epithelium, basement membrane, capillary endothelium.

• Surfactant: Reduces surface tension, prevents alveolar collapse.

• Respiratory Volumes: Tidal volume, inspiratory/expiratory reserve, residual volume, capacities.

• Gas Exchange: External (lungs), internal (tissues).

• Oxygen Transport: Mostly bound to hemoglobin.

• CO2 Transport: Dissolved, bound to hemoglobin, as bicarbonate.

• Oxygen-Hemoglobin Curve: Right shift (↓affinity) with ↑temperature or ↓pH; left shift (↑affinity) with ↓temperature or ↑pH.

• Chloride Shift: Exchange of Cl− and HCO3− in RBCs during CO2 transport.

• CO2 Reaction: $\mathrm{CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^-}$

• Respiratory Centers: Medulla and pons regulate breathing.

Endocrine System

Hormone Function and Regulation

• Nervous vs. Endocrine: Nervous is fast, short-term; endocrine is slower, long-term.

• Hormone Classes: Amino acid-based (e.g., insulin), steroids (e.g., cortisol).

• Transport and Receptors: Steroids use intracellular receptors; amino acid-based use membrane receptors.

• Second Messengers: cAMP, DAG, IP3; hormones activate specific pathways.

• Hormone Interactions: Permissiveness, synergism, antagonism.

• Major Glands: Hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, thymus.

• Local Messengers: Eicosanoids (prostaglandins, leukotrienes).

• Stress Response: General adaptation syndrome; hormones include cortisol, epinephrine.

• Disorders: Hyper/hyposecretion leads to diseases (e.g., diabetes, Cushing's, Addison's).

Digestive System

Structure and Function

• Functions: Ingestion, digestion, absorption, elimination.

• GI Tract Layers: Mucosa, submucosa, muscularis externa, serosa/adventitia.

• Mesenteries: Support and anchor digestive organs.

• Saliva: Contains enzymes (amylase), lubricates food.

• Pharynx: Nasopharynx (air), oropharynx/laryngopharynx (air and food).

• Gastric Glands/Intestinal Crypts: Secrete digestive enzymes, acid, hormones.

• Motility: Segmentation (mixing), peristalsis (propulsion).

• Small Intestine: Duodenum, jejunum, ileum; increased surface area via folds, villi, microvilli.

• GI Hormones: Gastrin, CCK, secretin, GIP.

• Autonomic Effects: Parasympathetic stimulates, sympathetic inhibits digestion.

• Digestive Phases: Cephalic, gastric, intestinal.

• HCl Secretion: Parietal cells, regulated by neural and hormonal signals.

• Enteric Nervous System: Local control of GI function.

• Digestive Enzymes: Amylase, proteases, lipases; each with specific substrates and products.

• Emulsification: Bile salts break down fats for digestion.

• Absorption: Monosaccharides, amino acids, fatty acids absorbed via specific mechanisms.

Nutrition and Metabolism

• Metabolic Rate: Rate of energy expenditure; basal rate measured at rest, fasting, thermoneutrality.

• Factors Affecting Metabolism: Age, sex, hormones, activity.

• Thermoregulation: Maintenance of body temperature.

• Absorptive vs. Post-Absorptive States: Absorptive (insulin-dominated), post-absorptive (glucagon-dominated).

• Key Terms: Glycogenesis (glucose → glycogen), glycolysis (glucose breakdown), ketogenesis (ketone production), lipogenesis (fat synthesis), lipolysis (fat breakdown), gluconeogenesis (glucose from non-carbs).

• LDL vs. HDL: LDL delivers cholesterol to tissues; HDL removes cholesterol.

• Liver Functions: Metabolism, vitamin storage, detoxification, bilirubin processing.

Urinary System

• Functions: Excretion, regulation of blood volume/composition, acid-base balance.

• Structures: Kidneys, ureters, bladder, urethra; nephron is functional unit.

• Nephron Types: Cortical (short loops), juxtamedullary (long loops).

• Juxtaglomerular Apparatus (JGA): Regulates blood pressure and GFR.

• Urine Formation: Filtration (glomerulus), reabsorption, secretion.

• GFR: Rate of filtration; maintained by autoregulation, hormones.

• Renin-Angiotensin System: Renin → angiotensin I → angiotensin II; increases BP.

• Hormones: ADH (water reabsorption), aldosterone (Na+ reabsorption), ANP (inhibits Na+ reabsorption).

• Micturition Reflex: Urination controlled by autonomic and voluntary pathways.

Water, Electrolyte, and Acid-Base Balance

• ECF vs. IF: Extracellular fluid (outside cells), interstitial fluid (between cells).

• Water Balance: Intake (drinking, food), loss (urine, sweat, respiration).

• Imbalances: Dehydration, hypovolemia, water intoxication, fluid overload; affect osmolarity.

• Hormonal Responses: ADH, aldosterone, ANP adjust water and electrolyte balance.

• Buffer Systems: Bicarbonate, protein, phosphate buffers maintain pH.

• Acidosis/Alkalosis: pH < 7.35 (acidosis), pH > 7.45 (alkalosis).

• Acid-Base Disorders: Respiratory/metabolic acidosis/alkalosis; causes include lung/kidney dysfunction.

• Compensation: Respiratory or renal adjustments to restore pH.

Reproductive System

• Structures: Male (testes, ducts, glands, penis), female (ovaries, tubes, uterus, vagina).

• Functions: Gamete production, hormone secretion, fertilization, support of offspring.

• Hormones: FSH, LH, estrogen, progesterone, testosterone regulate reproduction.

• Oogenesis vs. Spermatogenesis: Egg vs. sperm production; oogenesis includes meiosis and follicle development.

• Ovarian Cycle: Follicular, ovulation, luteal phases; regulated by hormones.

• Uterine Cycle: Menstrual, proliferative, secretory phases; endometrial changes.

• Meiosis: Two divisions produce haploid gametes; increases genetic variability.

• Gamete Pathways: Oocyte: ovary → uterine tube → uterus. Sperm: epididymis → vas deferens → urethra.