Exam 2 Study Guide Notes

Exam 2 Study Guide: Cardiovascular System

Functions of the Cardiovascular System

  • Transports oxygen, nutrients, hormones, and immune cells.

  • Removes metabolic waste products.

  • Regulates body temperature.

Pulmonary and Peripheral Circulations

  • Pulmonary Circulation: Transports blood between the heart and lungs for gas exchange.

  • Peripheral (Systemic) Circulation: Transports blood between the heart and the rest of the body.

Pathway of Blood Movement in Peripheral Circulation

  • Left Ventricle -> Aorta -> Arteries -> Arterioles -> Capillaries -> Venules -> Veins -> Vena Cava -> Right Atrium

Structures of the Heart

  • Chambers: Right Atrium, Right Ventricle, Left Atrium, Left Ventricle

  • Valves: Tricuspid (Right AV valve), Mitral (Bicuspid, Left AV valve), Pulmonary valve, Aortic valve

Pathway of Blood Through the Heart

  • Superior/Inferior Vena Cava -> Right Atrium -> Tricuspid Valve -> Right Ventricle -> Pulmonary Valve -> Pulmonary Artery -> Lungs -> Pulmonary Veins -> Left Atrium -> Mitral Valve -> Left Ventricle -> Aortic Valve -> Aorta -> Systemic Circulation

Blood Supply to Cardiac Muscles

  • Coronary arteries supply blood to the heart muscle (myocardium).

Left Anterior Descending Artery (LAD)

  • Also known as the "widow maker".

  • Supplies blood to the anterior wall of the left ventricle.

  • Blockage can lead to significant cardiac damage or death.

Phases of the Cardiac Cycle

  • Systole: Contraction phase, blood is ejected from the ventricles.

  • Diastole: Relaxation phase, ventricles fill with blood.

Intrinsic Regulation of the Cardiac Cycle

  • Sinoatrial (SA) Node: Initiates the electrical signal.

  • Atrioventricular (AV) Node: Delays the signal, allowing atria to contract before ventricles.

  • Bundle of His and Purkinje Fibers: Rapidly transmit the signal to ventricular muscle cells.

Extrinsic Regulation of the Cardiac Cycle

  • Autonomic Nervous System:

    • Sympathetic: Increases heart rate and contractility.

    • Parasympathetic: Decreases heart rate.

  • Hormones:

    • Epinephrine and norepinephrine increase heart rate and contractility.

Myocardium

  • Cardiac muscle tissue.

  • Similar to skeletal muscle: striated, contains actin and myosin.

  • Unique features:

    • Intercalated discs with gap junctions allow for rapid electrical conduction.

    • Involuntary control.

    • Aerobic metabolism.

Relevance of Cardiac Wall Thickness

  • Increased thickness can indicate adaptations to exercise or pathological conditions.

  • Exercise-induced hypertrophy: Enlargement of the heart muscle due to exercise.

  • Pathological hypertrophy: Enlargement of the heart muscle due to disease, such as hypertension.

  • Differentiation: Exercise-induced hypertrophy is often associated with normal or improved cardiac function, whereas pathological hypertrophy is associated with impaired function.

Electrocardiogram (ECG)

  • Measures the electrical activity of the heart.

ECG Waves

  • P wave: Atrial depolarization.

  • QRS complex: Ventricular depolarization.

  • T wave: Ventricular repolarization.

Cardiac Output (Q)

  • The amount of blood pumped by the heart per minute.

  • Equation: Q=HRvertSVQ = HR vert SV

    • HR = Heart Rate (beats per minute)

    • SV = Stroke Volume (milliliters per beat)

Regulation of Cardiac Output

  • Heart rate and stroke volume are regulated by nervous, hormonal, and intrinsic factors.

Stroke Volume (SV)

  • The amount of blood ejected from the left ventricle per beat.

  • Equation: SV=EDV−ESVSV = EDV - ESV

    • EDV = End-Diastolic Volume (volume of blood in ventricle at the end of diastole)

    • ESV = End-Systolic Volume (volume of blood in ventricle at the end of systole)

Ejection Fraction (EF)

  • The percentage of blood ejected from the left ventricle with each contraction.

  • Equation: EF=(SV/EDV)∗100EF = (SV / EDV) * 100

  • Normal EF: 55-70%

Heart Rate (HR) Regulation

  • Rest to Exercise:

    • Increased sympathetic activity.

    • Decreased parasympathetic activity.

    • Hormonal influence (epinephrine).

Stroke Volume (SV) Regulation

  • Preload: The degree of stretch on the ventricular muscle before contraction (EDV).

  • Afterload: The resistance against which the heart pumps (aortic pressure).

  • Contractility: The force of ventricular contraction.

Frank-Starling Mechanism

  • The heart's ability to increase its force of contraction when venous return increases. Increase EDV will cause increase SV.

Physiological Mechanisms to Increase Venous Return

  • Venoconstriction.

  • Skeletal muscle pump.

  • Respiratory pump.

Left Ventricular Training Adaptations to Exercise

  • Endurance Training: Increased left ventricular volume (eccentric hypertrophy).

  • Resistance Training: Increased left ventricular wall thickness (concentric hypertrophy).

Blood Pressure Definitions

  • Systolic Blood Pressure (SBP): The highest pressure in the arteries during ventricular contraction.

  • Diastolic Blood Pressure (DBP): The lowest pressure in the arteries during ventricular relaxation.

  • Pulse Pressure (PP): The difference between SBP and DBP (PP=SBP−DBPPP = SBP - DBP).

  • Mean Arterial Pressure (MAP): The average pressure in the arteries during one cardiac cycle.

Determinants of MAP

  • Cardiac output and total peripheral resistance.

  • Equation: MAP=Q<br>vertTPRMAP = Q <br>vert TPR

Regulation of MAP

  • Short-term: Nervous system (baroreceptors).

  • Long-term: Kidneys (blood volume).

Plasma

  • The fluid component of blood.

  • Consists of water, proteins, electrolytes, hormones and nutrients.

  • Approximately 55% of total blood volume (TBV).

  • During intense physical activity: Plasma volume decreases due to sweating and fluid shifts.

Formed Elements

  • Red blood cells, white blood cells, and platelets.

  • Approximately 45% of TBV.

Red Blood Cells (RBC)

  • Function: transport oxygen bound to hemoglobin.

Plasma and RBCs After Chronic Aerobic Training

  • Both plasma volume and RBC volume increase, but plasma volume increases more, leading to a lower hematocrit.

Hematocrit

  • The percentage of blood volume that is composed of red blood cells.

  • Decreases after chronic endurance training due to an increase in plasma volume.

Laws Governing Blood Flow

  • Blood flows from high pressure to low pressure.

  • Blood flow is proportional to the pressure difference and inversely proportional to resistance.

Blood Flow Equation

  • BloodFlow=(PressureGradient)/ResistanceBlood Flow = (Pressure Gradient) / Resistance

  • Pressure gradient: The difference in pressure between two points in the circulation.

  • Resistance: The opposition to blood flow.

Resistance Equation

  • Resistance=(Length<br>vertViscosity)/Radius4Resistance = (Length <br>vert Viscosity) / Radius^4

  • Length: Length of the blood vessel.

  • Viscosity: Thickness of the blood.

  • Radius: Radius of the blood vessel (most important factor).

Main Variable in Resistance During Exercise

  • Radius of blood vessels, primarily arterioles, due to vasodilation and vasoconstriction.

Compartment with Largest Drop in Resistance

  • Arterioles.

Gatekeepers of Blood Flow

  • Arterioles, due to their ability to vasoconstrict and vasodilate.

Fick Equation

  • VO<em>2=Qvert(a−vO</em>2difference)VO<em>2 = Q vert (a-vO</em>2 difference)

  • VO2VO_2 = Oxygen consumption

  • Q = Cardiac output (oxygen delivery component)

  • a−vO2differencea-vO_2 difference = Arteriovenous oxygen difference (oxygen utilization component)

  • a−vO2differencea-vO_2 difference at rest: ~5 mL O2/100 mL blood

  • a−vO2differencea-vO_2 difference during exercise: ~15-16 mL O2/100 mL blood

Redistribution of Blood Flow During Exercise

  • Active Skeletal Muscle: Increased blood flow due to vasodilation.

  • Inactive Skeletal Muscle: Decreased blood flow due to vasoconstriction.

  • Splanchnic Organs (liver, intestines, stomach): Decreased blood flow due to vasoconstriction.

  • Heart: Increased blood flow due to vasodilation.

  • Cardiac Output to Skeletal Muscle

    • Rest: ~15-20%

    • Maximal Exercise: ~80-85%

Factors Regulating Redistribution of Blood Flow

  • Vasoconstriction:

    • Sympathetic nervous system activity.

    • Hormones (epinephrine, norepinephrine).

  • Vasodilation:

    • Local factors (metabolic byproducts).

    • Nitric oxide.

Factors Regulating Vasoconstriction

  • Sympathetic nervous system, epinephrine, norepinephrine.

Factors Regulating Vasodilation

  • Local metabolites (adenosine, H+, CO2), nitric oxide.

Acute Responses to Exercise

  • Cardiac Output: Increases.

  • Stroke Volume: Increases.

  • Heart Rate: Increases.

  • Systolic Blood Pressure (SBP): Increases.

  • Diastolic Blood Pressure (DBP): Stays the same or slightly decreases.

  • Pulse Pressure (PP): Increases.

  • Mean Arterial Pressure (MAP): Increases.

  • Systemic Vascular Resistance (SVR): Decreases.

Exercise Training Adaptations

  • Cardiac Output: Increases at maximal exercise.

  • Stroke Volume: Increases at rest and during exercise.

  • Heart Rate: Decreases at rest and submaximal exercise.

  • Systolic Blood Pressure (SBP): Decreases at rest and submaximal exercise.

  • Diastolic Blood Pressure (DBP): Decreases at rest and submaximal exercise.

  • Pulse Pressure (PP): Increases at maximal exercise.

  • Mean Arterial Pressure (MAP): Decreases at rest and submaximal exercise.

  • Systemic Vascular Resistance (SVR): Decreases.

  • Vasodilation: Increased.

  • Vasoconstriction: Unchanged or decreased.

  • Maximal Oxygen Consumption (VO2max): Increases.

Exam 2 Study Guide: Respiratory System

Definitions

  • Pulmonary Ventilation: Movement of air into and out of the lungs.

  • Pulmonary Diffusion: Exchange of gases between the lungs and the blood.

  • Gas Transport: Movement of gases in the blood.

  • Capillary Gas Exchange: Exchange of gases between the blood and the tissues.

  • Pulmonary Respiration: Ventilation + Diffusion (external respiration).

  • Cellular Respiration: Oxygen use and carbon dioxide production by the tissues (internal respiration).

Path of Air in the Respiratory System

  • Nose/Mouth -> Pharynx -> Larynx -> Trachea -> Bronchi -> Bronchioles -> Alveoli

Anatomical Dead-Space

  • The volume of air in the respiratory system that does not participate in gas exchange.

  • Areas: Nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles.

Functions of the Respiratory System

  • Gas exchange (O2 and CO2).

  • Acid-base balance.

  • Ventilation.

Alveoli

  • Small air sacs in the lungs where gas exchange occurs.

  • Structure: Thin walls, large surface area, surrounded by capillaries.

  • Process of Gas Exchange: Oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli.

Pleural Membranes

  • Visceral Pleura: Membrane that covers the lungs.

  • Parietal Pleura: Membrane that lines the chest wall.

  • Intrapleural Pressure (IPP): Pressure in the space between the visceral and parietal pleura. It is negative to prevent lung collapse.

  • Relevance of IPP: Maintains the lungs' inflation by creating a suction effect.

Pressure Changes During Ventilation

  • Inspiration: Diaphragm contracts, increasing the volume of the thoracic cavity, decreasing intrapulmonary pressure, causing air to rush into the lungs.

  • Expiration: Diaphragm relaxes, decreasing the volume of the thoracic cavity, increasing intrapulmonary pressure, causing air to rush out of the lungs.

Inspiration and Expiration

  • Inspiration: Active process (requires muscle contraction).

  • Expiration: Passive process (usually, except during exercise).

Air Flow Equation

  • AirFlow=(PressureDifference)/ResistanceAir Flow = (Pressure Difference) / Resistance

  • How to increase air flow: Increase the pressure difference or decrease the resistance.

Biggest Factor Affecting Airflow at Rest

  • Resistance in the airways.

Bronchodilation

  • Dilation of the airways, decreasing resistance and increasing airflow.

  • Causes: Epinephrine, norepinephrine, and local factors.

Ventilation and Tidal Volume (TV)

  • Ventilation (VE): The volume of air moved into and out of the lungs per minute.

  • Tidal Volume (TV): The volume of air inhaled or exhaled per breath.

VE Equation

  • VE=TV<br>vertBreathingFrequencyVE = TV <br>vert Breathing Frequency

  • VE = Minute ventilation (L/min)

  • TV = Tidal volume (L/breath)

  • Breathing Frequency = (breaths/min)

TV and Breathing Frequency During Exercise

  • Both tidal volume and breathing frequency increase during exercise.

Equipment to Measure Lung Capacity and Volumes

  • Spirometer.

Lung Volumes Definitions

  • TV (Tidal Volume): Volume of air inhaled or exhaled per breath.

  • TLC (Total Lung Capacity): Total volume of air the lungs can hold.

  • IC (Inspiratory Capacity): Maximum volume of air that can be inhaled after a normal exhalation.

  • VC (Vital Capacity): Maximum volume of air that can be exhaled after a maximum inhalation.

  • FRC (Functional Residual Capacity): Volume of air remaining in the lungs after a normal exhalation.

  • RV (Residual Volume): Volume of air remaining in the lungs after a maximum exhalation.

  • ERV (Expiratory Reserve Volume): Maximum volume of air that can be exhaled after a normal exhalation.

  • IRV (Inspiratory Reserve Volume): Maximum volume of air that can be inhaled after a normal inhalation.

Factors that Promote Diffusion

  • Large surface area.

  • Thin membrane.

  • Large pressure gradient.

Dalton's Law

  • The total pressure of a gas mixture is equal to the sum of the partial pressures of each gas in the mixture.

Fick's Law of Diffusion

  • The rate of gas transfer is proportional to the tissue area, the diffusion coefficient of the gas, and the difference in the partial pressure of the gas on the two sides of the tissue, and inversely proportional to the thickness.

Changes in Partial Pressure of Oxygen (PO2)

  • Atmosphere -> Alveoli -> Arterial Blood -> Tissues -> Venous Blood

  • PO2 decreases as oxygen is used by the tissues.

Changes in Partial Pressure of Carbon Dioxide (PCO2)

  • Tissues -> Venous Blood -> Arterial Blood -> Alveoli -> Atmosphere

  • PCO2 decreases as carbon dioxide is removed from the body.

Lung Blood Flow and Gas Diffusion

  • Increased lung blood flow can increase gas diffusion by maintaining the concentration gradient.

Oxygen Transport by Red Blood Cells

  • Oxygen binds to hemoglobin in red blood cells.

Oxyhemoglobin Dissociation Curve

  • Relationship between PO2 and hemoglobin saturation.

  • Low PO2: Hemoglobin releases oxygen.

  • High PO2: Hemoglobin binds oxygen.

Factors Affecting the Oxyhemoglobin Dissociation Curve

  • Temperature:

    • Increased temperature shifts the curve to the right (more oxygen released).

    • Decreased temperature shifts the curve to the left (less oxygen released).

  • Acidity:

    • Increased acidity (lower pH) shifts the curve to the right (more oxygen released).

    • Decreased acidity (higher pH) shifts the curve to the left (less oxygen released).

2,3-Diphosphoglycerate (2,3-DPG)

  • A molecule in red blood cells that affects hemoglobin's affinity for oxygen.

  • Increases with altitude and chronic exercise training.

  • Shifts the oxyhemoglobin dissociation curve to the right (more oxygen released).

Carbon Dioxide Transport

  • Dissolved in plasma (7-10%).

  • Bound to hemoglobin (20-30%).

  • As bicarbonate (60-70%).

Myoglobin

  • Oxygen-binding protein found in muscle tissue.

  • Function: Transports oxygen from the cell membrane to the mitochondria.

Respiratory Control Center

  • Located in the medulla oblongata and pons of the brainstem.

  • Function: Regulates breathing rate and depth.

Central Chemoreceptors

  • Located in the medulla oblongata.

  • Function: Respond to changes in the pH of the cerebrospinal fluid (CSF).

  • Main Variables: Increased PCO2 and decreased pH stimulate ventilation.

Peripheral Chemoreceptors

  • Located in the carotid bodies and aortic bodies.

  • Function: Respond to changes in PO2, PCO2, pH, and potassium in the blood.

  • Main Variables: Decreased PO2, increased PCO2, and decreased pH stimulate ventilation.

Pulmonary Ventilation Response to Exercise

  • Rest to Submaximal Exercise: Ventilation increases rapidly, then plateaus.

  • Rest to Maximal Exercise: Ventilation increases linearly up to about 50-75% VO2max, then increases exponentially.

Ventilatory Equivalents

  • The ratio of ventilation to oxygen consumption (VE/VO2) or carbon dioxide production (VE/VCO2).

Ventilatory Threshold (VT)

  • The point at which ventilation increases disproportionately to oxygen consumption during incremental exercise.

Respiratory Compensation Point (RCP)

  • The point at which ventilation increases disproportionately to carbon dioxide production during incremental exercise.

Ventilatory Limits

  • Respiratory muscle fatigue.

  • Airway resistance.

  • Pulmonary diffusion capacity.


Consider a middle-aged man who decides to start an exercise program to improve his cardiovascular fitness.

Scenario:

  • He begins a routine of moderate-intensity aerobic exercises, such as cycling and jogging, for at least 150 minutes per week.

Application of Concepts:

  1. Increased Cardiac Output (Q):

    • As he continues exercising, his cardiac output increases due to enhanced stroke volume (SV) and heart rate (HR). The equation Q=HR×SVQ = HR \times SV explains that cardiac output depends on both heart rate and stroke volume.

  2. Stroke Volume Adaptations:

    • Regular exercise leads to physiological adaptations such as increased left ventricular volume (eccentric hypertrophy) allowing the heart to pump more blood per beat. This is characterized by increased end-diastolic volume (EDV) and reduced end-systolic volume (ESV). The stroke volume equation SV=EDV−ESVSV = EDV - ESV becomes increasingly favorable.

  3. Improved Ejection Fraction (EF):

    • Over time, the man's ejection fraction, defined as EF=(SV/EDV)×100EF = (SV / EDV) \times 100, improves, indicating more efficient heart function with normal EF being above 55%.

  4. Blood Pressure Regulation:

    • During exercise, the increase in systolic blood pressure (SBP) indicates higher cardiac output, while diastolic blood pressure (DBP) remains stable or decreases. Long-term exercise leads to a decrease in resting blood pressure, improving overall cardiovascular health.

  5. Vasodilation and Blood Flow Redistribution:

    • His regular aerobic workouts activate vasodilation in active skeletal muscles, leading to increased blood flow during exercise while reducing flow to inactive muscles and organs. This concept is explained by the Fick equation VO<em>2=Q×(a−vO</em>2 difference)VO<em>2 = Q \times (a - vO</em>2 \ difference), which signifies enhanced oxygen delivery and consumption.

Conclusion:

  • After several months of consistent exercise, this man experiences improved cardiovascular fitness, evidenced by reduced resting heart rate, better overall energy levels, and increased stamina. The application of cardiovascular physiology principles illustrates how exercise boosts various heart functions, highlighting the significant benefits of engaging in a regular fitness routine.