Cardiovascular & Respiratory System: Exam 2 Study Guide

Cardiovascular System

Key Anatomical Structures and Definitions

The cardiovascular system consists of the heart, blood vessels, and blood, working together to transport nutrients, gases, and wastes throughout the body.

• Anastomoses: Connections between blood vessels that allow for alternative routes of blood flow.

• Bradycardia: Abnormally slow heart rate, typically below 60 beats per minute.

• Tachycardia: Abnormally fast heart rate, typically above 100 beats per minute.

• Angina pectoris: Chest pain due to reduced blood flow to the heart muscle.

• Cardiac tamponade: Compression of the heart by fluid in the pericardial sac.

• Pericarditis: Inflammation of the pericardium, the membrane surrounding the heart.

• Ductus arteriosus: Fetal blood vessel connecting the pulmonary artery to the aorta; closes after birth.

Heart Structures and Valves

The heart contains specialized structures and valves that regulate blood flow and maintain efficient circulation.

• Ligamentum arteriosum: Remnant of the ductus arteriosus in adults.

• Auricles: Ear-like extensions of the atria that increase atrial volume.

• Pectinate muscles: Muscular ridges in the atria.

• Fossa ovalis: Depression in the right atrium, remnant of the fetal foramen ovale.

• Foramen ovale: Fetal opening between the atria, allowing blood to bypass the lungs.

• Trabeculae carneae: Irregular muscular columns in the ventricles.

• Valvular prolapse: Condition where a heart valve does not close properly, allowing backflow.

Cardiac Function and Pathology

Understanding cardiac function is essential for recognizing pathological conditions and their effects on the body.

• Myocardial infarction: Heart attack; death of heart muscle due to lack of oxygen.

• Chronotropic effects: Changes in heart rate (positive increases, negative decreases).

• Inotropic effects: Changes in contractility of the heart muscle (positive increases, negative decreases).

• Congestive heart failure: Condition where the heart cannot pump blood effectively.

• Cardiac reserve: Difference between resting and maximal cardiac output.

• Baroreceptors: Pressure sensors in blood vessels that regulate blood pressure.

• Chordae tendineae: Tendinous cords that anchor heart valves.

• Papillary muscles: Muscles that attach to chordae tendineae and prevent valve prolapse.

Pulmonary and Systemic Circuits

The heart pumps blood through two main circuits: pulmonary (to the lungs) and systemic (to the body).

• Pulmonary circuit: Carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium.

• Systemic circuit: Carries oxygenated blood from the left ventricle to the body and returns deoxygenated blood to the right atrium.

Coronary Circulation

The coronary circulation supplies blood to the heart muscle itself, ensuring its metabolic needs are met.

• Coronary arteries: Branches from the aorta that supply the heart.

• Coronary veins: Drain deoxygenated blood from the heart muscle into the right atrium.

Heart Wall Structure

The heart wall consists of three layers, each with distinct functions.

• Epicardium: Outer layer; provides protection.

• Myocardium: Middle layer; composed of cardiac muscle responsible for contraction.

• Endocardium: Inner layer; lines the chambers and valves.

Ventricular Wall Thickness

The thickness of the ventricular walls reflects the workload of each ventricle.

• Left ventricle: Thicker wall to pump blood throughout the body.

• Right ventricle: Thinner wall, pumps blood to the lungs.

Heart Valves: Structure and Function

Heart valves ensure unidirectional blood flow and prevent backflow.

• Atrioventricular (AV) valves: Tricuspid (right) and bicuspid/mitral (left).

• Semilunar valves: Pulmonary and aortic valves.

• Valve opening/closing: Controlled by pressure differences across the valves.

Blood Flow Through the Heart

Blood flows through the heart in a specific sequence, passing through chambers and valves.

1. Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs

2. Lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aortic valve → aorta → body

Heart Autorhythmicity

The heart is autorhythmic, meaning it can generate its own electrical impulses without external stimulation.

• Sinoatrial (SA) node: Pacemaker of the heart.

• Atrioventricular (AV) node: Delays impulse before passing to ventricles.

Role of Calcium (Ca2+) in the Heart

Calcium ions are essential for cardiac muscle contraction and electrical activity.

• Ca2+ influx triggers contraction in cardiac muscle cells.

• Regulates strength and duration of contraction.

Intrinsic Conduction Pathway

The heart's conduction system coordinates contraction.

• SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers

• Each part ensures timely and coordinated contraction.

Electrocardiogram (ECG) Waves

An ECG records the electrical activity of the heart.

• P wave: Atrial depolarization.

• QRS complex: Ventricular depolarization.

• T wave: Ventricular repolarization.

Cardiac Rhythms and Pacemakers

Cardiac rhythms are regulated by the conduction system; artificial pacemakers may be needed if the system fails.

• Normal rhythm: Sinus rhythm from SA node.

• Artificial pacemaker: Device that maintains heart rate when natural pacemaker fails.

Autonomic Regulation of the Heart

The autonomic nervous system modulates heart rate and contractility.

• Parasympathetic (acetylcholine): Decreases heart rate.

• Sympathetic (epinephrine): Increases heart rate and contractility.

Heart Sounds

Heart sounds are produced by valve closure.

• "Lub" (S1): Closure of AV valves.

• "Dub" (S2): Closure of semilunar valves.

Cardiac Cycle

The cardiac cycle describes the sequence of events in one heartbeat.

• Systole: Contraction phase.

• Diastole: Relaxation phase.

Cardiac Output and Related Equations

Cardiac output is the volume of blood pumped by the heart per minute.

• CO (Cardiac Output): $CO = HR \times SV$

• HR (Heart Rate): Beats per minute.

• SV (Stroke Volume): Volume of blood pumped per beat.

• EDV (End-Diastolic Volume): Volume in ventricle at end of filling.

• ESV (End-Systolic Volume): Volume in ventricle after contraction.

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

Preload, Afterload, and Contractility

These factors influence cardiac performance.

• Preload: Degree of stretch of cardiac muscle before contraction.

• Afterload: Resistance the heart must overcome to eject blood.

• Contractility: Strength of contraction at a given preload.

Frank-Starling Law

The Frank-Starling law states that increased ventricular filling leads to increased stroke volume.

• Greater stretch = stronger contraction.

Ischemia and Concerns

Ischemia is reduced blood supply to tissues; the main concern is lack of oxygen.

• Oxygen deprivation: Can lead to tissue damage or infarction.

Blood Vessels and Circulation

Blood vessels transport blood throughout the body and are classified by structure and function.

• Aneurysm: Abnormal bulge in a blood vessel wall.

• Artery: Carries blood away from the heart.

• Vein: Carries blood toward the heart.

• Precapillary sphincters: Regulate blood flow into capillaries.

• Anastomoses: Alternate pathways for blood flow.

• Portal systems: Vessels connecting two capillary beds.

Blood Pressure and Related Terms

Blood pressure is the force exerted by blood on vessel walls.

• Perfusion: Delivery of blood to tissues.

• Mean arterial pressure (MAP): Average pressure in arteries during one cardiac cycle.

• Systolic: Pressure during ventricular contraction.

• Diastolic: Pressure during ventricular relaxation.

• MAP equation: $MAP = \text{Diastolic} + \frac{1}{3}(\text{Systolic} - \text{Diastolic})$

Blood Pressure Disorders

• Orthostatic hypotension: Drop in blood pressure upon standing.

• Hypotension: Abnormally low blood pressure.

• Hypertension: Abnormally high blood pressure.

Venous Return and Capacitance

Veins are high capacitance vessels, able to store large volumes of blood.

• Factors aiding venous return: Muscle pump, respiratory pump, venous valves.

• Baroreceptors: Detect changes in blood pressure and initiate compensatory mechanisms.

Hormonal Regulation of Blood Pressure

Various hormones influence blood pressure.

• Angiotensin II: Vasoconstriction, increases BP.

• Aldosterone: Increases sodium and water retention.

• Alcohol: Vasodilation, decreases BP.

Blood Flow and Resistance Relationships

Blood flow is affected by viscosity, vessel diameter, and length.

• Peripheral resistance: Opposition to blood flow.

• Blood viscosity: Thickness of blood.

• Vessel diameter: Smaller diameter increases resistance.

• Blood flow equation: $Q = \frac{\Delta P}{R}$

Capillary Exchange and Edema

Hydrostatic and osmotic pressures regulate fluid movement in capillaries.

• Hydrostatic pressure: Pushes fluid out of capillaries.

• Osmotic pressure: Pulls fluid into capillaries.

• Edema: Excess fluid accumulation in tissues.

Types of Shock

Shock is a life-threatening condition due to inadequate tissue perfusion.

• Hypovolemic shock: Due to blood loss.

• Cardiogenic shock: Due to heart failure.

• Distributive shock: Due to abnormal distribution of blood flow.

Respiratory System

Functions and Components

The respiratory system provides gas exchange, regulates blood pH, and protects against pathogens.

• Major components: Nose, pharynx, larynx, trachea, bronchi, lungs.

Pharynx Regions and Importance

• Nasopharynx: Air passageway.

• Oropharynx: Passage for food and air.

• Laryngopharynx: Connects to larynx and esophagus.

Laryngeal Muscles

• Intrinsic muscles: Control vocal cord tension.

• Extrinsic muscles: Move the larynx as a whole.

Respiratory Zones

• Conducting zone: Passages that transport air (nose to bronchioles).

• Respiratory zone: Sites of gas exchange (alveoli).

Respiratory Tree and Membrane

• Respiratory tree: Branching airways from trachea to alveoli.

• Respiratory membrane: Site of gas exchange; consists of alveolar and capillary walls.

Mucociliary Escalator

The mucociliary escalator removes debris from the respiratory tract.

• Cilia move mucus upward toward the pharynx.

Inspiration and Expiration

• Inspiration: Diaphragm contracts, thoracic volume increases.

• Expiration: Diaphragm relaxes, thoracic volume decreases.

• Quiet vs. forced: Quiet uses diaphragm; forced uses accessory muscles.

Gas Laws

Gas laws govern the movement of gases in the respiratory system.

• Boyle's Law: $P_1V_1 = P_2V_2$ (pressure and volume are inversely related).

• Dalton's Law: Total pressure is the sum of partial pressures.

• Henry's Law: Gas solubility in liquid is proportional to partial pressure.

Resistance and Airflow

• Airway diameter affects resistance; smaller diameter increases resistance.

Respiratory Volumes and Capacities

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

• Vital Capacity (VC): Maximum amount of air exhaled after maximum inhalation.

Alveolar Ventilation Rate

• Equation: $AVR = (TV - \text{dead space}) \times \text{respiratory rate}$

Transport of CO2 and O2 in Blood

• Oxygen: Mostly bound to hemoglobin.

• Carbon dioxide: Dissolved, bound to hemoglobin, or as bicarbonate.

Utilization Coefficient and Venous Reserve

• Utilization coefficient: Percentage of oxygen released from hemoglobin.

• Venous reserve: Oxygen remaining in venous blood.

Hemoglobin Loading/Unloading

• Factors: pH, temperature, CO2 levels, 2,3-BPG.

Haldane Effect

The Haldane effect describes how oxygenation of blood affects CO2 transport.

• Deoxygenated hemoglobin binds CO2 more readily.

Neural Control of Breathing

• Hypothalamus, medulla oblongata, pons: Regulate breathing rate and rhythm.

• Chemoreceptors: Detect changes in CO2, O2, and pH.

Acid-Base Balance and Disorders

• Respiratory acidosis: High CO2, low pH.

• Respiratory alkalosis: Low CO2, high pH.

• Metabolic acidosis/alkalosis: Due to non-respiratory causes.

Gas Exchange and Ventilation

• Oxygen and carbon dioxide are exchanged by diffusion across the respiratory membrane.

• Partial pressures ($P_{O_2}$ and $P_{CO_2}$) drive gas movement.

Disorders of the Respiratory System

• Includes asthma, COPD, pneumonia, and others.

Additional info:

• Some definitions and relationships were expanded for clarity and completeness.

• Equations and formulas were provided for key physiological calculations.

• Table formatting was not required as no tables were present in the original material.