Anatomy & Physiology II: Study Guide for Exam 2

Anatomy & Physiology II: Study Guide for Exam 2

Introduction

This study guide covers key concepts in cardiovascular and respiratory physiology, including heart anatomy, blood flow, cardiac cycle, blood pressure regulation, and respiratory system function. The guide is structured to help students prepare for exam questions by providing definitions, explanations, and examples relevant to each topic.

Cardiovascular System

Heart Anatomy and Blood Flow

• Chambers of the Heart: The heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle.

• Valves: The heart contains atrioventricular (AV) valves (tricuspid and bicuspid/mitral) and semilunar valves (pulmonary and aortic). These ensure unidirectional blood flow.

• Blood Flow Pathway: Blood flows from the body into the right atrium, right ventricle, lungs (via pulmonary artery), left atrium, left ventricle, and out to the body (via aorta).

• Major Vessels: Superior/inferior vena cava, pulmonary arteries/veins, and aorta.

• Coronary Circulation: Supplies blood to the heart muscle itself.

Cardiac Cycle and Heart Sounds

• Cardiac Cycle: The sequence of events in one heartbeat, including atrial and ventricular systole and diastole.

• Heart Sounds: "Lub" (S1) is caused by closure of AV valves; "Dub" (S2) is caused by closure of semilunar valves.

• Electrical Conduction System: Includes the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers.

• Electrocardiogram (ECG): Records the electrical activity of the heart. P wave = atrial depolarization, QRS complex = ventricular depolarization, T wave = ventricular repolarization.

Cardiac Output and Regulation

• Cardiac Output (CO): The volume of blood pumped by each ventricle per minute. $CO = HR \times SV$ where HR = heart rate, SV = stroke volume.

• Stroke Volume (SV): The amount of blood ejected by a ventricle with each beat.

• Factors Affecting CO: Preload, afterload, contractility, and heart rate.

• Autonomic Regulation: Sympathetic stimulation increases HR and contractility; parasympathetic decreases HR.

Blood Pressure and Vascular System

• Blood Pressure (BP): The force exerted by blood on vessel walls. $BP = CO \times TPR$ (Total Peripheral Resistance).

• Regulation: Short-term (baroreceptors, chemoreceptors, autonomic nervous system) and long-term (renal mechanisms, hormones such as ADH, aldosterone, and ANP).

• Vessel Types: Arteries (carry blood away from heart), veins (return blood to heart), capillaries (exchange of gases/nutrients).

• Capillary Exchange: Occurs via diffusion, filtration, and osmosis. Hydrostatic and osmotic pressures determine net movement.

Blood Components and Functions

• Plasma: The liquid component of blood, containing water, proteins, nutrients, hormones, and waste products.

• Formed Elements: Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

• Hematocrit: The percentage of blood volume occupied by red blood cells.

Respiratory System

Respiratory Anatomy and Mechanics

• Major Structures: Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli.

• Alveoli: Site of gas exchange; surrounded by capillaries.

• Respiratory Membrane: Thin barrier for gas exchange between alveolar air and blood.

• Ventilation: Movement of air in and out of the lungs. Inspiration is active (diaphragm contracts), expiration is usually passive.

• Pressure Changes: Air flows from high to low pressure. Intrapulmonary and intrapleural pressures are key.

Gas Exchange and Transport

• External Respiration: Exchange of O2 and CO2 between alveoli and blood.

• Internal Respiration: Exchange of O2 and CO2 between blood and tissues.

• Oxygen Transport: Mostly bound to hemoglobin; a small amount dissolved in plasma.

• Carbon Dioxide Transport: Dissolved in plasma, bound to hemoglobin, or as bicarbonate ion ($CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^-$).

• Partial Pressures: $P_{O_2}$ and $P_{CO_2}$ drive diffusion of gases.

Control of Respiration

• Respiratory Centers: Medulla oblongata and pons regulate rate and depth of breathing.

• Chemoreceptors: Detect changes in $CO_2$, $O_2$, and pH in blood and CSF.

• Other Factors: Stretch receptors, irritant receptors, higher brain centers.

Respiratory Volumes and Capacities

• Tidal Volume (TV): Amount of air inhaled or exhaled in a normal breath.

• Inspiratory Reserve Volume (IRV): Additional air that can be inhaled after a normal inspiration.

• Expiratory Reserve Volume (ERV): Additional air that can be exhaled after a normal expiration.

• Residual Volume (RV): Air remaining in lungs after maximal exhalation.

• Vital Capacity (VC): $VC = TV + IRV + ERV$

• Total Lung Capacity (TLC): $TLC = VC + RV$

Tables

Comparison of Blood Vessel Types

Vessel Type	Function	Wall Structure	Pressure
Artery	Carry blood away from heart	Thick, muscular, elastic	High
Vein	Return blood to heart	Thin, less muscular, valves present	Low
Capillary	Exchange of gases/nutrients	Single cell layer (endothelium)	Very low

Additional Info

• Starling's Law of the Heart: The greater the stretch of cardiac muscle fibers (preload), the greater the force of contraction.

• Frank-Starling Mechanism: Explains how changes in venous return affect stroke volume.

• Mean Arterial Pressure (MAP): $MAP = \frac{1}{3} (SBP - DBP) + DBP$ where SBP = systolic BP, DBP = diastolic BP.

• Bohr Effect: Increased $CO_2$ or decreased pH reduces hemoglobin's affinity for O2, enhancing oxygen delivery to tissues.

• Haldane Effect: Deoxygenated blood can carry more $CO_2$.