BIO 2350L Midterm 2: Hematology, ECG, Blood Pressure & Spirometry

What happens when whole blood is centrifuged?

Blood separates by density into three layers: plasma on top, a thin buffy coat in the middle, and red blood cells at the bottom.

What is hematocrit?

The percentage of whole-blood volume made up of red blood cells (RBCs).

What is plasma?

The liquid part of blood, containing mostly water plus proteins, electrolytes, nutrients, hormones, dissolved gases, and wastes.

What is the buffy coat?

The thin layer of white blood cells (WBCs) and platelets between plasma and red blood cells.

What do red blood cells do?

Carry oxygen using hemoglobin and carry some carbon dioxide.

What do white blood cells do?

Help defend the body against pathogens and other threats.

What do platelets do?

Help form a platelet plug and support blood clotting.

What does albumin do?

Helps maintain osmotic pressure and transports some substances.

What does fibrinogen do?

A plasma protein that is converted to fibrin during blood clotting.

What can low hematocrit and low RBC count indicate?

Anemia; it may result from blood loss, reduced RBC production, or increased RBC destruction.

What does an ECG record?

Electrical potential changes at the skin caused by the heart's electrical activity.

What does the P wave represent?

Atrial depolarization.

What does the QRS complex represent?

Ventricular depolarization; atrial repolarization occurs around this time and is hidden by the QRS complex.

What does the T wave represent?

Ventricular repolarization.

What is the isoelectric line?

The baseline with no net electrical potential difference detected by that lead.

What is a segment in ECG?

A section between waves, such as the PR segment or ST segment.

What is an interval in ECG?

A time span that includes one or more waves and usually a segment, such as the PR interval or QT interval.

What is the cardiac cycle?

One complete heartbeat, including atrial and ventricular contraction and relaxation.

What is systole?

The contraction/ejection phase; systolic pressure is the peak arterial pressure during ventricular contraction.

What is diastole?

The relaxation/filling phase; diastolic pressure is the lowest arterial pressure between ventricular contractions.

Trace the heart's electrical conduction pathway.

SA node → atrial muscle/internodal pathways → AV node (brief delay) → bundle of His → right and left bundle branches → Purkinje fibers → ventricular myocardium.

What does the SA node do?

Normally starts each heartbeat and acts as the heart's natural pacemaker.

What does the AV node do?

Briefly delays the signal so the ventricles have time to fill before they contract.

How does inhalation affect heart rate?

Heart rate usually rises slightly during inhalation.

How does exhalation affect heart rate?

Heart rate usually falls slightly during exhalation; this normal variation is respiratory sinus arrhythmia.

How can body position affect ECG recordings?

Changing posture can alter heart orientation relative to the electrodes and may change ECG amplitude or shape.

How can physical activity affect the ECG?

Exercise usually increases heart rate, shortening the R-R interval; the ECG reflects faster electrical cycles.

How do you calculate heart rate from an R-R interval?

Heart rate (beats/min) = 60 ÷ R-R interval (seconds).

What is the baroreflex?

A negative-feedback reflex in which pressure sensors in the carotid sinus and aortic arch detect stretch and help adjust autonomic output, heart rate, and vessel tone to stabilize blood pressure.

How does a blood pressure cuff measure pressure?

The cuff temporarily compresses the brachial artery; as cuff pressure is slowly released, blood flow and sounds return in a pattern that indicates systolic and diastolic pressure.

What is occlusion?

Blocking or greatly reducing blood flow by applying pressure to a vessel.

What is auscultation?

Listening to internal body sounds, typically with a stethoscope over the brachial artery.

What are Korotkoff sounds?

Sounds heard over the artery as blood spurts through a partly compressed artery while cuff pressure is between systolic and diastolic pressure.

What happens when cuff pressure is above systolic pressure?

The artery is occluded; no blood passes through and Korotkoff sounds are absent.

What happens when cuff pressure is between systolic and diastolic pressure?

Blood passes intermittently through the partly compressed artery; Korotkoff sounds are heard.

What happens when cuff pressure is below diastolic pressure?

The artery stays open through the cardiac cycle and turbulent sounds disappear.

Which Korotkoff sound marks systolic pressure?

The first clear Korotkoff sound as cuff pressure falls.

Which Korotkoff sound marks diastolic pressure?

Usually the disappearance of Korotkoff sounds (Phase V) in adults.

How might manual and computer blood-pressure measurements differ?

Manual values are based on listening for Korotkoff sounds; computer systems may detect pressure changes algorithmically.

What is systolic pressure (SP)?

The highest arterial pressure during ventricular contraction.

What is diastolic pressure (DP)?

The lowest arterial pressure between ventricular contractions.

What is pulse pressure (PP)?

SP − DP.

What is mean arterial pressure (MAP)?

At a normal resting heart rate, estimated MAP = DP + 1/3(SP − DP).

How does dynamic exercise usually affect blood pressure?

Systolic pressure rises; diastolic pressure often stays about the same or changes only slightly.

How can seated and supine positions affect blood pressure?

Posture changes venous return and autonomic responses; supine and seated values can differ.

What is cardiac output (CO)?

The volume of blood pumped by one ventricle per minute, calculated as CO = heart rate × stroke volume.

What does total peripheral resistance (TPR) refer to?

The resistance to blood flow offered by systemic blood vessels, especially arterioles.

What is the relationship between flow, pressure, and resistance?

Flow = pressure difference ÷ resistance.

What factors can increase heart rate and contractility?

Sympathetic activity and circulating epinephrine/norepinephrine.

What is respiration?

The overall process of moving air and exchanging gases between the atmosphere, lungs, blood, and tissues.

What does spirometry measure?

How much air a person moves and how quickly they can exhale.

What is tidal volume (TV)?

The amount of air inhaled or exhaled during a normal quiet breath.

What is inspiratory reserve volume (IRV)?

Extra air that can be inhaled after a normal inhalation.

What is expiratory reserve volume (ERV)?

Extra air that can be forcibly exhaled after a normal exhalation.

What is residual volume (RV)?

Air remaining in the lungs after maximal exhalation; cannot be measured directly by standard spirometry.

What is inspiratory capacity (IC)?

The maximum amount inhaled after a normal exhalation, calculated as TV + IRV.

What is functional residual capacity (FRC)?

The amount of air remaining in the lungs after a normal exhalation, calculated as ERV + RV.

What is vital capacity (VC)?

The maximum amount of air exhaled after a maximal inhalation, calculated as IRV + TV + ERV.

What is total lung capacity (TLC)?

The total air in the lungs after maximal inhalation, calculated as VC + RV.

What factors affect predicted lung volumes?

Height, age, sex, and sometimes ancestry/population reference factors.

What is forced expiratory volume (FEV1)?

The volume of air forcibly exhaled in the first second after a full inhalation.

How do you calculate FEV1 as a percentage of FVC?

FEV1% = (FEV1 ÷ FVC) × 100.

What is maximum voluntary ventilation (MVV)?

The greatest volume of air a person can breathe in and out over a specified time during rapid, deep breathing.

How might MVV be calculated from a short recording?

MVV = V × (60/t) L/min, where V is the volume collected and t is the time in seconds.

What effect does airway constriction have?

It increases airway resistance, often reducing FEV1 and the FEV1/FVC ratio.

What do obstructive and restrictive patterns indicate?

Obstructive conditions make it harder to move air out quickly; restrictive conditions limit lung expansion.

What are spirometry tests used for?

Assessing airflow and ventilatory function, identifying patterns consistent with obstructive or restrictive problems.

What is the formula for mean arterial pressure (MAP)?

MAP ≈ DP + 1/3(SP − DP).

What is the formula for calculating FEV1 percent?

FEV1 percent = (FEV1 / FVC) × 100.

What are the three layers of centrifuged blood?

Top: plasma; Middle: buffy coat; Bottom: RBCs.

What is the ECG wave for atrial depolarization?

P wave.

What is the full cardiac conduction pathway?

SA node → atrial myocardium/internodal pathways → AV node → bundle of His → right/left bundle branches → Purkinje fibers → ventricular myocardium.