A&P Chapter 19-22 (Exam 2)

Trace oxygen-poor blood from the body through the right heart to the lungs.

Superior vena cava / inferior vena cava → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lung capillaries

Trace oxygen-rich blood from the lungs through the left heart to the body.

Pulmonary veins → left atrium → mitral valve → left ventricle → aortic semilunar valve → aorta → systemic arteries and tissues.

The process by which the right side of the heart pumps blood to the lungs for gas exchange, with pulmonary veins returning oxygenated blood to the left atrium.

Pulmonary Circuit

Process that describes when the left ventricle ejects oxygenated blood through the aorta to body tissues; systemic veins return oxygen-poor blood to the right atrium.

Systemic Circuit

Why can a pulmonary artery carry oxygen-poor blood while a pulmonary vein carries oxygen-rich blood?

Arteries are defined by carrying blood away from the heart, and veins by carrying blood toward the heart, regardless of oxygen level.

Which chambers of the heart receive blood

Right and Left Atrium

What makes the heart valves open and close?

Pressure gradients across the valves cause them to open when the pressure behind the valve is greater and close when pressure in front of the valve becomes greater

The phase of the heartbeat when the heart muscle contracts and pumps blood out of its chambers into the arteries is called:

Systole

The phase of the heartbeat when the heart muscle relaxes and its chambers fill with blood is called:

Diastole

The phase when the ventricles contract and eject blood into the pulmonary trunk and aorta is called:

Ventricular Systole

The phase when the ventricles relax and fill with blood, while arterial pressure falls to its lowest level between contractions, is called:

Ventricular Diastole

Why does diastole matter beyond simply allowing the heart to “rest”?

It allows the ventricles to fill for the next stroke volume and supports coronary blood flow as the myocardium relaxes

Why is systolic pressure usually higher than diastolic pressure?

Ventricular ejection stretches the arterial walls and raises pressure, while pressure falls as blood continues through the vessels during ventricular relaxation

How do atrial systole and ventricular systole relate during the cardiac cycle?

Atrial systole tops off ventricular filling, then ventricular systole follows and ejects blood

What are the four heart sounds called?

S1 (“lub”), S2 (“dub”), S3, and S4

What produces the first heart sound, “lub” (S1), at the beginning of ventricular systole?

Closure of the mitral and tricuspid (AV) valves

What produces the second heart sound, “dub” (S2), as ventricular systole ends and diastole begins?

Closure of the aortic and pulmonary semilunar valves

What is the normal cardiac conduction sequence?

SA node → atrial myocardium → AV node → AV bundle → right/left bundle branches → Purkinje fibers → ventricular myocardium

Why does cardiac conduction slow briefly at the AV node?

The delay allows the atria to finish contracting and the ventricles to fill before ventricular depolarization and contraction

What does automaticity mean in cardiac muscle?

Pacemaker and other autorhythmic cells can spontaneously depolarize, allowing the heart to initiate its own electrical impulses

What is the SA node’s normal role in cardiac conduction?

It normally fires fastest, sets the heart’s sinus rhythm, and initiates the electrical impulse that spreads through the atria

What is an ectopic focus, and how can it alter cardiac rhythm?

An ectopic focus is an impulse source outside the SA node that can fire early or take over pacing, causing premature beats or an abnormal activation pathway

What is a heart block physiologically?

A delay or interruption in electrical conduction from the atria toward the ventricles, causing ventricular activation to be slowed or to fail to follow atrial activation

What can make an abnormal cardiac rhythm more likely during myocardial ischemia?

Reduced oxygen delivery disrupts ATP production and ion gradients in cardiac cells, altering electrical conduction and increasing the risk of arrhythmias

How do sympathetic and parasympathetic input affect heart rate?

Sympathetic stimulation increases heart rate, while parasympathetic stimulation decreases heart rate

What does the P wave represent on an ECG?

Atrial depolarization

What does the QRS complex represent on an ECG?

Ventricular depolarization

What does the T wave represent on an ECG?

Ventricular repolarization

How do electrical and mechanical events relate during the cardiac cycle?

Electrical depolarization and repolarization occur before the corresponding contraction and relaxation of cardiac muscle

What is cardiac output, and how is it calculated?

Cardiac output is the amount of blood ejected by one ventricle per minute and is calculated as heart rate × stroke volume; it helps support tissue perfusion

Why can ventricular tachycardia reduce cardiac output?

Rapid ventricular activation shortens filling time and can reduce coordinated ejection and stroke volume, which can compromise tissue perfusion

How does coronary circulation supply the heart itself?

The right and left coronary arteries branch near the beginning of the aorta and deliver oxygenated blood to the myocardium; cardiac veins drain deoxygenated blood toward the coronary sinus and right atrium

What defines arteries and veins?

Arteries carry blood away from the heart, while veins carry blood toward the heart; the distinction is based on direction, not oxygen content

Put the systemic vessel pathway in the correct order.

Aorta/arteries → arterioles → capillaries → venules → veins → venae cavae

What is the usual order of the three vessel-wall tunics from innermost to outermost?

Tunica interna (intima) → tunica media → tunica externa (adventitia)

How do artery and vein walls differ in relation to blood pressure?

Arteries have thicker, more muscular and elastic walls to withstand higher pressure, while veins operate at lower pressure and expand more readily

What does systolic blood pressure represent?

The peak arterial pressure produced during ventricular contraction and blood ejection

What does diastolic blood pressure represent?

The arterial pressure between ventricular ejections while the ventricles relax and fill

What does diastolic blood pressure represent?

The arterial pressure between ventricular ejections while the ventricles relax and fill

Why are both systolic and diastolic blood pressure values useful?

Together they show the peak arterial pressure during ventricular ejection and the pressure maintained between beats, reflecting both cardiac pumping and vascular function

What is pulse pressure?

Systolic pressure minus diastolic pressure; it reflects the change in arterial pressure with each heartbeat

These factors determine arterial blood pressure

Cardiac output, blood volume, and resistance to blood flow

How does cardiac output connect the heart to blood pressure?

Changes in heart rate or stroke volume change cardiac output; higher cardiac output tends to raise arterial pressure, while lower cardiac output tends to reduce it when other factors remain similar

How does arteriolar radius affect resistance and blood pressure?

Narrowing arterioles increases resistance and tends to raise upstream arterial pressure, while widening arterioles decreases resistance and allows more blood to reach downstream capillaries

What term describes changes in vessel diameter caused mainly by smooth-muscle contraction or relaxation that help regulate regional blood flow and arterial pressure?

Vasomotion

What happens in the baroreceptor reflex when arterial pressure rises?

Increased arterial stretch increases baroreceptor firing, reducing sympathetic vasomotor tone and increasing vagal influence, which lowers heart rate and promotes vasodilation

What is the longer-term compensatory pathway triggered by low blood pressure in which reduced kidney perfusion promotes renin release, leading to vasoconstriction, thirst, and sodium/water retention?

Renin–angiotensin–aldosterone system (RAAS)

Why do venous valves and the skeletal muscle pump matter?

They help low-pressure venous blood return to the heart by preventing backflow and using skeletal-muscle contractions to push blood toward the chest

How does the respiratory pump assist venous return?

Pressure changes during breathing help draw venous blood toward the thorax and right atrium

Where does systemic blood pressure drop most sharply, and what are examples of these vessels?

Across small arteries and arterioles, such as terminal arterioles supplying skeletal muscle, skin, and organ capillary beds, where resistance is high

What drives capillary filtration and reabsorption?

Blood hydrostatic pressure pushes fluid out of capillaries, while osmotic pressure from plasma proteins pulls fluid back in; lymphatics recover excess filtered fluid

How can a mismatch between right- and left-ventricle output cause edema?

If one ventricle pumps less effectively, pressure backs up behind it; left-sided backup can increase pulmonary pressure, while right-sided backup can cause systemic edema

Why can a normal pulse be felt in an artery?

Ventricular ejection creates a pressure wave that travels through arterial walls, producing the palpable pulse

What are the three lines of defense in the immune system?

External barriers; nonspecific internal defenses; and specific defenses with memory

What is the difference between innate and adaptive immunity?

Innate immunity responds quickly and broadly, while adaptive immunity targets specific antigens and can form immunologic memory

What do neutrophils and macrophages contribute to immune defense?

Both can engulf pathogens; neutrophils respond rapidly, while monocytes can enter tissues and differentiate into macrophages

How do natural killer (NK) cells destroy abnormal cells?

They release perforins that form openings in the target-cell membrane and granzymes that trigger cell death

What is complement, and what can it do?

A cascade of plasma proteins that can promote inflammation, coat pathogens for easier phagocytosis, and form membrane-attack complexes that damage target cells

What does an antigen-presenting cell do?

It processes an antigen and displays a fragment with an MHC protein so an appropriate T cell can recognize it

What is the key difference between helper T cells and cytotoxic T cells?

Helper T cells coordinate immune responses by releasing cytokines, while cytotoxic T cells directly kill infected or abnormal cells

What do activated B cells become, and what do they produce?

Activated B cells can become plasma cells that secrete antibodies or memory B cells that support a faster future immune response

How do antibodies help defend the body?

They bind specific antigens, can neutralize or clump targets, and tag them for removal by other immune mechanisms

What is immunological memory?

Long-lived memory B and T cells allow a faster, stronger immune response when the body is exposed again to the same antigen

Trace the airflow pathway from the nose to the gas-exchange region.

Nasal/oral cavity → pharynx → larynx → trachea → main bronchi → lobar bronchi → segmental bronchi → bronchioles → respiratory bronchioles → alveolar ducts/sacs → alveoli

What changes as airways branch into bronchioles?

Cartilage is lost and smooth muscle becomes more prominent, allowing bronchiolar diameter to change airway resistance and airflow

What is the difference between the right and left lungs?

The right lung has three lobes, while the left lung has two lobes and a cardiac notch

What is the role of the pleurae and pleural fluid?

The visceral and parietal pleurae surround the lungs, and pleural fluid reduces friction while helping couple lung movement to the thoracic wall

What happens to the diaphragm during inspiration?

It contracts and descends, increasing thoracic volume; intrapulmonary pressure falls below atmospheric pressure, causing air to flow into the lungs

What happens during quiet expiration?

The diaphragm and inspiratory muscles relax, thoracic volume decreases, intrapulmonary pressure rises above atmospheric pressure, and air flows out

Why does air move into or out of the lungs?

Air moves down a pressure gradient: negative intrapulmonary pressure relative to atmospheric pressure draws air in, while positive intrapulmonary pressure pushes air out

How does surfactant help keep alveoli open?

It lowers surface tension at the air–fluid interface, reducing the tendency of small alveoli to collapse

What structures form the respiratory membrane?

The thin alveolar squamous cell layer, shared basement membrane, and capillary endothelial layer that separate alveolar air from blood

In which directions do O₂ and CO₂ diffuse at the lungs?

O₂ diffuses from alveolar air into pulmonary capillary blood, while CO₂ diffuses from the blood into the alveoli; both move down their partial-pressure gradients

How does pulmonary blood become oxygenated?

Oxygen-poor blood enters pulmonary capillaries from the pulmonary arteries, gains O₂ and releases CO₂, then returns through the pulmonary veins to the left atrium

How does oxygen travel from the alveoli to systemic tissues?

O₂ enters pulmonary capillary blood, binds mainly to hemoglobin in red blood cells, returns to the left heart, and travels through systemic arteries to the tissues

How is most CO₂ transported from systemic tissues to the lungs?

Most CO₂ is converted to bicarbonate in red blood cells, carried in plasma, then converted back to CO₂ in pulmonary capillaries and exhaled

Why does CO₂ affect blood pH?

CO₂ combines with water to form carbonic acid, which can release H⁺; changing ventilation changes CO₂ removal and therefore changes blood pH

What is the relationship between ventilation and perfusion?

Ventilation brings air to the alveoli, while perfusion brings blood to alveolar capillaries; efficient gas exchange requires the two to be regionally matched

What is anatomical dead space, and why does it matter?

It is air in the conducting passages that does not participate in gas exchange, reducing the portion of each breath available for alveolar ventilation

What is the clinical connection between pulmonary edema and gas exchange?

Fluid in lung tissue or alveoli increases the diffusion distance for gases, reducing oxygen transfer; left-sided heart failure can cause this pulmonary fluid buildup

What is hypoxia?

Inadequate oxygen at the tissue level, which can result from low blood oxygen, reduced tissue perfusion, or insufficient oxygen-carrying capacity

What is Inhalation

Inhalation is the active, muscular phase of breathing in which the diaphragm and intercostal muscles contract

An abnormal heart rhythm is a

Dysrhythmia

What can trigger a premature ventricular contraction (PVC)?

A ventricular ectopic focus fires before the next expected sinus impulse, often from irritated or damaged ventricular tissue

How can ventricular tachycardia progress to ventricular fibrillation?

Rapid abnormal ventricular activation can become disorganized, causing the ventricles to quiver without effective coordinated ejection

How do ventricular fibrillation and asystole differ electrically?

Ventricular fibrillation has chaotic electrical activity without effective pumping, while asystole is the absence of detectable cardiac electrical activity