Cardiovascular, Immune, and Respiratory Systems: Study Guide for Anatomy & Physiology

Cardiovascular System: Blood Vessels, Flow, and Pressure

Types of Blood Vessels: Structure, Location, and Function

• Arteries: Thick-walled, high-pressure vessels that carry blood away from the heart. Their elastic and muscular layers allow for pressure regulation and distribution.

• Veins: Thin-walled, low-pressure vessels that return blood to the heart. Contain valves to prevent backflow.

• Capillaries: Microscopic vessels with thin walls (single endothelial layer) for exchange of gases, nutrients, and wastes between blood and tissues.

• Comparison: Arteries have thicker walls and more smooth muscle than veins; capillaries are smallest and most permeable.

• Location: Arteries are deep, veins are both deep and superficial, capillaries are found in all tissues.

• Function: Arteries transport blood under high pressure; veins return blood under low pressure; capillaries facilitate exchange.

Blood Flow Equation

• Relationship: Blood flow (F) is determined by the pressure difference (ΔP) divided by resistance (R).

$F = \Delta P / R$

• Application: Increasing pressure or decreasing resistance increases flow.

Peripheral Resistance

• Factors: Vessel diameter, blood viscosity, and vessel length.

• Most Significant Factor: Vessel diameter (small changes greatly affect resistance).

• Impact: Narrower vessels increase resistance; thicker blood increases resistance.

Compensation for Severe Hemorrhage

• Homeostatic Mechanisms: Activation of baroreceptor reflexes, release of hormones (e.g., epinephrine, ADH, angiotensin II), vasoconstriction, increased heart rate.

• Goal: Maintain blood pressure and perfusion to vital organs.

Net Filtration Pressure and Fluid Exchange

• Forces: Capillary hydrostatic pressure, interstitial hydrostatic pressure, capillary osmotic pressure, interstitial osmotic pressure.

• Net Filtration Pressure (NFP): Determines direction of fluid movement.

$\text{NFP} = (\text{Capillary Hydrostatic Pressure} + \text{Interstitial Osmotic Pressure}) - (\text{Capillary Osmotic Pressure} + \text{Interstitial Hydrostatic Pressure})$

• Alterations: Increased capillary hydrostatic pressure or decreased capillary osmotic pressure promotes edema.

Atherosclerosis Effects

• Impact: Plaque buildup narrows arteries, increases resistance, raises blood pressure, and reduces blood flow.

Cardiovascular System: Lymph, Lymphatic Vessels, and Lymphoid Organs

Lymphatic Capillaries vs. Blood Capillaries

• Lymphatic Capillaries: More permeable, allow uptake of proteins and debris; have overlapping endothelial cells forming one-way valves.

• Blood Capillaries: Less permeable, primarily exchange gases and nutrients.

Lymphatic Vessels vs. Veins

• Lymphatic Vessels: Thinner walls, more valves, carry lymph toward the heart.

• Veins: Carry blood toward the heart, less permeable.

Thymus Function

• Role: Site of T cell maturation and immunocompetence.

Obstructed Lymphatic Flow

• Result: Edema due to accumulation of interstitial fluid.

Lymph Node Functions

• Filtration: Remove pathogens and debris from lymph.

• Immune Activation: Site for lymphocyte activation and proliferation.

Immune System

Pathogens

• Disease-causing organisms: Pathogens (e.g., Streptococcus bacteria, influenza virus).

Viral Effects on Host Cells

• Mechanism: Viruses invade cells, hijack cellular machinery, and cause cell death or dysfunction.

Innate Immune Response

• Definition: Non-specific, immediate defense against pathogens.

• Components: Skin, mucous membranes, phagocytes, inflammation, complement proteins.

• Memory: No memory; same response each time.

Body Surfaces in Immunity

• Role: Physical barriers (skin, mucosa) prevent pathogen entry.

Phagocytes in Immunity

• Function: Engulf and destroy pathogens (e.g., macrophages, neutrophils).

Inflammation

• Purpose: Limits spread of pathogens, removes debris, promotes healing.

Innate Immune Response Components

• Includes: Physical barriers, phagocytes, natural killer cells, inflammation, complement, interferons.

• Memory: Lacks memory.

Complement Proteins

• Role: Enhance phagocytosis, lyse pathogens, promote inflammation.

Interferons

• Function: Proteins produced by virus-infected cells; inhibit viral replication in neighboring cells.

• Memory: No memory.

Fever in Immunity

• Benefits: Inhibits pathogen growth, enhances immune response.

• Risks: High fever can damage tissues and proteins.

Humoral vs. Cell-Mediated Immunity

• Humoral: B cells produce antibodies.

• Cell-Mediated: T cells (TH, Tc) attack infected cells.

TH and Tc Cells

• TH (Helper T) Cells: Activate B cells and other T cells.

• Tc (Cytotoxic T) Cells: Destroy infected or abnormal cells.

Vaccines

• Mechanism: Introduce antigens to stimulate immune response and memory without causing disease.

Active vs. Passive Immunity

• Active: Body produces its own antibodies (e.g., infection, vaccination).

• Passive: Antibodies are transferred from another source (e.g., maternal antibodies, antiserum).

Primary vs. Secondary Immune Response

• Primary: First exposure, slower, less antibody production.

• Secondary: Subsequent exposure, faster, stronger response due to memory cells.

• Type: Both humoral and cell-mediated responses involved.

Immunocompetence

• Definition: Ability of B and T cells to recognize specific antigens.

• Location: B cells in bone marrow; T cells in thymus.

Antigens and Antibodies

• Antigen: Substance that triggers an immune response.

• Antibody: Protein produced by B cells that binds to antigens.

• Immunoglobulin Classes: IgG, IgM, IgA, IgE, IgD (each with distinct functions).

Immunoglobulin	Main Function
IgG	Most abundant; crosses placenta; opsonization
IgM	First produced; activates complement
IgA	Found in mucosal areas; protects surfaces
IgE	Allergic responses; defense against parasites
IgD	B cell receptor; initiates immune response

Respiratory System

Anatomical Structures and Functions

• Structures: Nose, pharynx, larynx, trachea, bronchi, lungs, alveoli.

• Functions: Air conduction, gas exchange, protection, vocalization.

Pathway of Inhaled Molecule

• Route: Nares → Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.

Pleurae

• Definition: Double-layered membranes surrounding lungs (visceral and parietal pleura).

• Function: Reduce friction, create pressure gradient, compartmentalize lungs.

Surfactant

• Importance: Reduces surface tension in alveoli, prevents collapse, aids in gas exchange.

Inspiration and Expiration

• Inspiration: Diaphragm contracts, thoracic volume increases, pressure decreases, air enters lungs.

• Expiration: Diaphragm relaxes, thoracic volume decreases, pressure increases, air exits lungs.

Gas Diffusion Variables (Fick's Law)

• Variables: Surface area, membrane thickness, partial pressure gradient, diffusion coefficient.

$\text{Rate of diffusion} = (\text{Surface Area} \times \text{Partial Pressure Difference} \times \text{Diffusion Coefficient}) / \text{Membrane Thickness}$

Internal vs. External Respiration

• External: Gas exchange between alveoli and blood.

• Internal: Gas exchange between blood and tissues.

Partial Pressure (Dalton's Law)

• Calculation: Partial pressure of a gas = total pressure × fraction of gas in mixture.

$P_{\text{gas}} = P_{\text{total}} \times \text{fraction of gas}$

Oxygen and Carbon Dioxide Transport

• Oxygen: Mostly bound to hemoglobin; some dissolved in plasma.

• Carbon Dioxide: Dissolved in plasma, bound to hemoglobin, or as bicarbonate.

Oxyhemoglobin Formation and Dissociation

• Formation: Promoted by high pO2, low temperature, low CO2, high pH.

• Dissociation: Promoted by low pO2, high temperature, high CO2, low pH.

Utilization Coefficient

• Definition: Percentage of oxygen released from hemoglobin to tissues.

SO2 vs. pO2

• SO2: Oxygen saturation; percentage of hemoglobin bound to oxygen.

• pO2: Partial pressure of oxygen; measure of oxygen concentration.

Respiratory Rate Control

• Controlled by: Medullary respiratory centers, chemoreceptors (CO2, O2, pH).

Tidal Volume

• Definition: Volume of air inhaled or exhaled in a normal breath.

• Average Value: ~500 mL in adults.

Acid/Base Balance: Hyperventilation and Hypoventilation

• Hyperventilation: Decreases CO2, causes respiratory alkalosis.

• Hypoventilation: Increases CO2, causes respiratory acidosis.

Factors Affecting Respiratory Rate

• Increase: High CO2, low O2, low pH, exercise, fever.

• Decrease: Low CO2, high pH, sleep, certain drugs.

Key Terms

• Hypocapnia: Low CO2 in blood.

• Hypercapnia: High CO2 in blood.

• Hypoxemia: Low O2 in blood.