Chapter 18-19: The Heart and Blood Vessels Overview

Pulmonary Circuit

Transports oxygen-poor blood to lungs for oxygenation.

Systemic Circuit

Delivers oxygenated blood to body tissues.

Atria

Upper chambers of the heart receiving blood.

Ventricles

Lower chambers of the heart pumping blood.

Pericardium

Double-walled sac enclosing the heart.

Fibrous Pericardium

Outer layer protecting and anchoring the heart.

Serous Pericardium

Inner layer with parietal and visceral components.

Pericardial Cavity

Space between pericardium layers containing serous fluid.

Epicardium

Visceral layer of the serous pericardium.

Myocardium

Muscular layer forming the bulk of the heart.

Endocardium

Inner lining of heart chambers, continuous with blood vessels.

Right Ventricle

Pumps blood into the pulmonary circuit.

Left Ventricle

Pumps blood into the systemic circuit.

Cardiac Muscle

Striated muscle with unique contraction mechanism.

Intercalated Discs

Connect cardiac cells for structural strength and communication.

Gap Junctions

Allow electrical impulses to pass between cardiac cells.

Sinoatrial Node

Primary pacemaker located in the right atrium.

Atrioventricular Node

Delays impulse before it passes to ventricles.

Atrioventricular Bundle

Conducts impulses from atria to ventricles.

Bundle Branches

Carry impulses to right and left ventricles.

Subendocardial Conducting Network

Distributes impulses throughout ventricular myocardium.

Sliding Filament Mechanism

Process of muscle contraction in cardiac fibers.

Atrioventricular (AV) node

Delays impulse to allow atrial contraction completion.

Atrioventricular (AV) bundle

Only electrical connection between atria and ventricles.

Right and left bundle branches

Conduct impulses down interventricular septum to apex.

Electrocardiograph

Monitors and records heart's electrical signals.

P wave

Indicates atrial depolarization in ECG.

QRS complex

Represents ventricular contraction in ECG.

T wave

Indicates ventricular repolarization in ECG.

First heart sound (lub)

Closure of AV valves during ventricular systole.

Second heart sound (dup)

Closure of aortic and pulmonary valves during diastole.

Heart murmurs

Turbulent blood flow through improperly closing valves.

Systole

Contractile phase of the cardiac cycle.

Diastole

Relaxation phase of the cardiac cycle.

Ventricular filling

Occurs during mid-to-late diastole with open AV valves.

Atrial contraction

Propels blood into ventricles at end of diastole.

Isovolumetric relaxation

Rapid drop in ventricular pressure during early diastole.

Cardiac output

Blood pumped out of ventricle per beat.

Stroke volume

Volume of blood pumped per beat, ~70 ml.

Average heart rate

Typical adult heart rate is 75 beats per minute.

Cardiac reserve

Difference between resting and maximal cardiac output.

End diastolic volume (EDV)

Blood volume in ventricle during diastole.

End systolic volume (ESV)

Blood volume remaining after ventricular contraction.

Frank-Starling law

Stroke volume controlled by preload stretch.

Venous return

Most important factor for cardiac muscle stretch.

Contractility

Strength of contraction at given muscle length.

Afterload

Ventricular pressure to overcome for blood ejection.

Sympathetic stimulation

Increases heart rate via Ca++ influx.

Parasympathetic inhibition

Decreases heart rate by enhancing K+ permeability.

Epinephrine

Hormone that elevates heart rate.

Thyroxine

Hormone that increases heart rate.

Ion imbalances

Disrupt normal heart function.

Tunica intima

Inner layer reducing friction in vessels.

Tunica media

Middle layer allowing vasoconstriction and vasodilation.

Tunica externa

Outer layer protecting and anchoring vessels.

Elastic arteries

Contain elastin to manage pressure fluctuations.

Muscular arteries

Deliver blood to organs with active vasoconstriction.

Arterioles

Smallest arteries regulating blood flow to capillaries.

Capillaries

Smallest vessels for substance exchange with tissues.

Continuous capillaries

Most common, allowing fluids and small solutes.

Fenestrated capillaries

More permeable to fluids and solutes.

Sinusoid capillaries

Leaky capillaries for large molecule passage.

Capillary beds

Networks for microcirculation and substance exchange.

Precapillary sphincter

Smooth muscle regulating blood flow into capillaries.

Venules

Formed from converging capillaries, allowing fluid movement.

Veins

Thin-walled vessels containing 65% of blood volume.

Blood flow

Volume of blood through a vessel per minute.

Blood pressure

Force exerted by blood against vessel walls.

Resistance

Friction between blood and vessel walls.

Peripheral resistance

Key factor affecting local blood flow.

Systemic blood pressure

Highest in aorta, declines to right atrium.

Systolic Pressure

Peak pressure during left ventricle contraction.

Diastolic Pressure

Pressure when ventricles are relaxed, 70-80 mm Hg.

Pulse Pressure

Difference between systolic and diastolic pressure.

Mean Arterial Pressure (MAP)

Average pressure propelling blood to tissues.

Capillary Blood Pressure

Low pressure (15-40 mm Hg) for tissue exchange.

Blood Volume

Total amount of blood in circulation.

Neural Controls

Short-term adjustments to blood pressure via nerves.

Cardiovascular Center

Medulla clusters regulating heart and vessel function.

Baroreceptors

Sensors detecting blood vessel stretch and pressure.

Chemoreceptors

Sensors responding to blood CO2 levels.

Vasodilation

Widening of blood vessels to decrease pressure.

Vasoconstriction

Narrowing of blood vessels to increase pressure.

Atrial Natriuretic Peptide

Hormone promoting vasodilation and reducing blood volume.

Antidiuretic Hormone (ADH)

Hormone increasing blood volume via water retention.

Angiotensin II

Hormone causing vasoconstriction and fluid retention.

Nitric Oxide

Vasodilator produced in response to high blood flow.

Inflammatory Chemicals

Substances like histamine that induce vasodilation.

Autoregulation

Intrinsic adjustment of blood flow to tissue needs.

Angiogenesis

Formation of new blood vessels over time.

Which of the following might trigger erythropoiesis?

Hypoxia of EPO-producing cells

Hematopoiesis

or blood cell formation, occurs in the _________., Red bone marrow

Which of the choices below is the parent cell for all formed elements of blood?

Hemocytoblast

Platelets ________.

Stick to the damaged area of a blood vessel and help seal the break

What organ in the body regulates erythrocyte production?

Kidney

An individual who is blood type AB negative can ________.

Receive any blood type in moderate amounts except that with the Rh antigen

Erythrocyte production is controlled by the hormone ________.

Erythropoietin (EPO)

Blood is an example of a ________ tissue.

Connective

________ is a situation leading to widespread clotting throughout intact vessels

and may occur as a complication of pregnancy, septicemia, or incompatible blood transfusions., Disseminated intravascular coagulation

Which of the following is an example of a bleeding disorder?

Hemophilia