Physiology Exam 03 – Cardiovascular, Blood Volume, and Respiratory Systems

Comprehensive review flashcards covering heart anatomy, cardiac electrophysiology, blood pressure and vessel dynamics, endocrine regulation of blood volume, and respiratory mechanics and gas exchange.

Which two heart chambers receive oxygenated pulmonary venous blood and pump it into systemic circulation?

The left atrium and left ventricle.

What is the heart valve located between the right atrium and right ventricle?

The tricuspid valve.

What is the heart valve located between the left atrium and left ventricle?

The bicuspid (mitral) valve.

What structure serves as the natural primary pacemaker of the heart?

The sinoatrial (SA) node.

Following the SA node, through which structures does the normal cardiac conduction pathway proceed?

The AV node, bundle branches, and Purkinje fibers.

What mechanical event primarily gives rise to the first and second heart sounds?

The closure of heart valves.

If the SA node ceases pacing and an AV junctional focus takes over, what is the expected heart rate?

Approximately $40$ to $60\,\text{beats/min}$.

Where does fluid tend to accumulate if one ventricle persistently pumps less blood than the other?

Upstream (behind) of the lower-output pump.

What electrical event in the heart is reflected by the ECG P wave?

Atrial depolarization.

What electrical event in the heart is reflected by the ECG QRS complex?

Ventricular depolarization.

What electrical event in the heart is reflected by the ECG T wave?

Ventricular repolarization.

Which ECG interval tends to lengthen when electrical conduction through the AV node is slowed?

The PR interval.

Which ECG interval spans ventricular depolarization through ventricular repolarization?

The QT interval.

Which cardiac rhythm is characterized by chaotic, ineffective electrical activity in the ventricles?

Ventricular fibrillation.

Through which specialized cell junctions do electrical signals spread directly between adjacent cardiac muscle cells?

Gap junctions.

Which specific ion channels produce the rapid upstroke in ventricular contractile cell action potentials?

Fast voltage-gated sodium ($\text{Na}^+$) channels.

The prolonged plateau phase of ventricular contractile cell action potentials is driven by the inward movement of which ions?

Calcium ($\text{Ca}^{2+}$) ions.

In cardiac pacemaker cells, what do funny channels help produce toward reaching threshold?

Gradual depolarization (pacemaker potential).

Sympathetic activation of which specific cardiac adrenergic receptors promotes an increase in intracellular cAMP?

Beta-1 ($\beta_1$) receptors.

What effect does the activation of muscarinic-linked potassium channels have on pacemaker cells to delay the next heartbeat?

It hyperpolarizes pacemaker cells.

How does an increase in the time required for SA-node cells to reach threshold affect heart rate?

It tends to decrease (slow) heart rate.

What are blood vessels that carry blood away from the heart called?

Arteries.

What are the primary blood vessels responsible for nutrient and gas exchange between blood and tissues?

Capillaries.

Why is blood flow velocity slowest across capillary beds?

Because their total cross-sectional area is very large (high).

What are the stretch-sensitive mechanoreceptors located in the carotid sinus and aortic arch called?

Baroreceptors.

What is the term for the numerical difference between systolic and diastolic blood pressure?

Pulse pressure.

How does an increase in either cardiac output or systemic vascular resistance affect mean arterial pressure?

It tends to increase mean arterial pressure.

During major blood loss, what compensatory changes typically occur in sympathetic activity and heart rate?

Sympathetic activity increases and heart rate tends to increase.

Following acute blood loss, what critical parameter may still remain inadequate even if blood pressure is compensated near normal?

Tissue perfusion.

What vascular response typically occurs in the superficial blood vessels of the fingers and toes upon exposure to cold?

Vasoconstriction.

What is the name of the first major branch originating from the aortic arch?

The brachiocephalic trunk.

At the arterial end of a systemic capillary, which Starling force favors fluid filtration outward into the interstitium?

Capillary hydrostatic pressure.

What type of pressure does plasma albumin generate to retain fluid within blood vessels?

Colloid osmotic (oncotic) pressure.

What physiological disturbance occurs when low plasma albumin decreases colloid osmotic pressure?

It promotes edema (excess fluid accumulation in the interstitial space).

Which two anatomical and mechanical mechanisms in the periphery prevent backflow and assist venous return to the heart?

The skeletal muscle pump and one-way venous valves.

What pump utilizes rhythmic changes in intrathoracic pressure during respiration to aid venous return?

The respiratory pump.

In the RAAS pathway, which organ synthesizes angiotensinogen, and which organ secretes renin?

The liver produces angiotensinogen, and the kidneys release renin.

Which enzymatic reaction is catalyzed by angiotensin-converting enzyme (ACE)?

Conversion of angiotensin I to angiotensin II.

Which endocrine gland releases aldosterone in response to activation of the RAAS pathway?

The adrenal gland (specifically the adrenal cortex).

What are two primary actions of angiotensin II on blood vessels and hormone secretion?

It causes arteriolar vasoconstriction and stimulates aldosterone secretion.

Which electrolyte does aldosterone act on the kidneys to reabsorb, thereby indirectly promoting water retention?

Sodium ($\text{Na}^+$).

By what cellular mechanism does antidiuretic hormone (ADH) increase renal water reabsorption?

By encouraging insertion of aquaporins into collecting duct membranes.

What physiological effect on fluid balance results from blocking ADH-responsive aquaporin insertion?

It increases fluid (water) loss in urine.

What hormone is released by cardiac myocytes in response to atrial stretch caused by high circulating blood volume?

Atrial natriuretic peptide (ANP).

Which two substances does ANP promote the renal excretion of to counteract volume expansion?

Sodium and water.

What respiratory term designates the volume of air moved into or out of the lungs during a quiet breath?

Tidal volume.

What respiratory volume is defined as the extra air that can be inhaled above a normal tidal inspiration?

Inspiratory reserve volume (IRV).

What respiratory volume is defined as the extra air that can be forcefully exhaled below a normal tidal expiration?

Expiratory reserve volume (ERV).

What is the volume of air that remains inside the lungs even after a maximal exhalation?

Residual volume (RV).

What type of dead space comprises the air occupying conducting airways that does not participate in gas exchange?

Anatomical dead space.

What type of dead space is formed by ventilated alveoli that fail to participate effectively in gas exchange?

Alveolar dead space.

What is the mathematical formula used to calculate alveolar ventilation?

$\text{Alveolar ventilation} = (\text{tidal volume} - \text{dead space}) \times \text{breathing rate}$.

According to Boyle’s law, what relationship exists between the pressure and volume of a gas at constant temperature?

An inverse (indirect) relationship.

How does contraction of the diaphragm during inspiration facilitate the inward movement of air?

It increases thoracic volume, which lowers alveolar pressure below atmospheric pressure.

Under what pressure condition relative to atmospheric pressure does air move out of the lungs during exhalation?

When intra-alveolar pressure is greater (higher) than atmospheric pressure.

What critical physical property inside alveoli is reduced by pulmonary surfactant?

Alveolar surface tension.

Which two regions of the brainstem house the neural centers responsible for respiratory rhythm and modulation?

The medulla and pons.

How do central chemoreceptors indirectly detect elevated arterial blood $\text{CO}_2$ levels?

Through changes in the $\text{pH}$ (or hydrogen ion concentration, $[\text{H}^+]$) of cerebrospinal fluid.

At a normal alveolar $\text{P}_{\text{O}_2}$ of approximately $100\,\text{mm Hg}$, what is the approximate saturation of hemoglobin?

Approximately $98\%$ (or $95\text{--}100\%$).

At a resting tissue $\text{P}_{\text{O}_2}$ of approximately $40\,\text{mm Hg}$, what is the approximate saturation of hemoglobin?

Approximately $75\%$.

In which direction does a decrease in blood pH shift the oxygen–hemoglobin dissociation curve?

To the right.

What effect do elevations in temperature and 2,3-BPG concentration have on oxygen delivery to peripheral tissues?

They favor oxygen unloading (release) to tissues.

How does the oxygen affinity of fetal hemoglobin compare to that of adult hemoglobin?

Fetal hemoglobin has a higher oxygen affinity.

In what form is the vast majority of oxygen transported through the bloodstream?

Bound to hemoglobin (as oxyhemoglobin).

In what chemical form is the majority of carbon dioxide transported in the blood?

As bicarbonate ions ($\text{HCO}_3^-$).

Which red blood cell enzyme accelerates the reversible hydration of $\text{CO}_2$ to form carbonic acid?

Carbonic anhydrase.

What is the exchange process at systemic tissues where chloride ions enter red blood cells as bicarbonate exits called?

The chloride shift.

What ion exchange occurs across red blood cell membranes at pulmonary capillaries during the reverse chloride shift?

Bicarbonate ions enter red blood cells while chloride ions exit.

What is the phenomenon called where elevated tissue $\text{CO}_2$ and $\text{H}^+$ promote oxygen dissociation from hemoglobin?

The Bohr effect.

Why does carbon dioxide diffuse efficiently across the respiratory membrane despite having a much smaller partial-pressure gradient than oxygen?

Because $\text{CO}_2$ is much more soluble in biological fluids than $\text{O}_2$.

Why does carbon monoxide severely impair arterial oxygen transport?

Because it binds with extremely high affinity to hemoglobin, displacing oxygen.

What acid-base disturbance is induced by acute hyperventilation due to excessive loss of arterial $\text{CO}_2$?

Respiratory alkalosis.

If conduction velocity through the AV node is pathologically delayed, how will the ECG be altered?

The PR interval will increase (lengthen).

If SA-node pacemaker cells become hyperpolarized and take longer to reach threshold, what happens to the interval between successive heartbeats?

The interval between heartbeats increases (lengthens, decreasing heart rate).

If a hemorrhaging patient compensates by systemic arteriolar vasoconstriction, what happens to vascular resistance and tissue perfusion?

Systemic resistance increases while tissue perfusion may still decrease or remain inadequate.

How does a pathological reduction in circulating plasma albumin affect fluid distribution in the interstitium?

Fluid accumulation in the interstitial space increases (promoting edema).

What occurs to urinary water excretion if ADH-dependent aquaporins are prevented from inserting into collecting duct membranes?

Urinary water excretion increases, producing large volumes of dilute urine.

What vascular pressure and fluid complication arise when the left ventricle fails to pump blood forward adequately?

Pulmonary circulation pressure increases, promoting pulmonary edema.

Why does pulmonary edema reduce the effectiveness of alveolar-capillary oxygen exchange?

Because it increases the physical diffusion distance across the respiratory membrane.

Which proteolytic enzyme is released by recruited neutrophils in response to smoke-derived ROS that destroys lung elastin?

Elastase.

Which circulating protease inhibitor protects lung alveolar walls by inhibiting neutrophil elastase?

Alpha-1 antitrypsin (AAT).

What are the three primary physiological determinants of cardiac stroke volume?

Preload, afterload, and contractility.

Why is active cool-down movement recommended after strenuous exercise to maintain venous return?

It sustains the action of the skeletal muscle pump to propel venous blood back to the heart.

From which ABO and Rh blood types can a patient with B-negative ($\text{B}^-$) blood safely receive packed red blood cells?

B-negative ($\text{B}^-$) and O-negative ($\text{O}^-$).

What happens to net outward capillary filtration when plasma albumin concentration is markedly elevated and capillary hydrostatic pressure is low?

Net outward capillary filtration tends to decrease (favoring fluid reabsorption into the capillary).