Vander's Human Physiology Chapter 12 | Quizlet

Bulk Flow

Movement of fluids from region of higher pressure to one of lower pressure; all constituents of blood that flows together

Erythrocytes

red blood cells

Formed Elements

cells and cell fragments

Hematocrit

percentage of blood volume that is erythrocytes (45% in men; 42% in women)

Hemodynamics

the relationship among blood pressure, blood flow, and the resistance to blood flow

Hydrostatic Pressure

the pressure exerted by any fluid

Leukocytes

white blood cells

Microcirculation

arterioles, capillaries, and venules

Plasma

the extracellular matrix of blood cells; 55% of the body's total blood volume

Platelets

cell fragments; used for blood clotting

Portal System

exceptions to the usual anatomical pattern of blood flow for some organs such as the liver and the anterior pituitary gland. Blood passes through two capillary beds, arranged in a series and connected by veins, before returning to the heart.

Resistance (R)

how difficult it is for blood to flow between two points at any given pressure difference; the measure of friction that impedes flow

Viscosity

one determinant of resistance; a function of the friction between molecules of a flowing fluid; the greater the friction, the greater the friction, the greater the viscosity

Absolute Refractory Period

the inability of the heart to generate tetanic contractions; the period during and following an AP when an excitable membrane cannot be re-excited. Because of the prolonged, depolarized plateau in the cardiac muscle AP, the absolute refractory period of cardiac muscle lasts almost as long as the contraction, and the muscle cannot be re-excited multiple times during an ongoing contraction

Afterload

the arterial pressures against which the ventricle pump

Atrioventricular (AV) Node

the portion of the conducting system that is the link between atrial depolarization and ventricular depolarization; located at the base of the right atrium; the propagation of action potentials through the AV node is relatively slow allowing atrial contraction to be completed before ventricular excitation occurs

Atrioventricular (AV) Valve

located between the atrium and ventricle in each half of the heart; one-way valves; permit blood to flow from atrium to ventricle but not backwards. Responsible for the "lub" sound.

Aortic Valve

opening of the left ventricle into the aorta ("dup" sound)

Automaticity

the capacity for spontaneous, rhythmic self-excitation provided to the SA node by the pacemaker potential.

Bicuspid Valve

the left AV valve

Bundle Branches

the right and left branches that the Bundle of His divides into; conducting fibers that separate at the bottom (apex) of the heart and enter the walls of both ventricles

Bundle of His

after the AV node has become excited, the AP propagates down the interventricular septum via this pathway; also called the atrioventricular bundle

Cardiac Cycle

orderly process of depolarization triggers this cycle of atrial and ventricular contractions and relaxations

Cardiac Output (CO)

the volume of blood each ventricle pumps as a function of time (liters per minute); in a steady state, the CO flowing through the systemic and pulmonary circuits is the same

Conduction System

Approx. 1% of cardiac cells that do not function in contraction but have specialized features that are essential for normal heart excitation; cells of the heart that are in electrical contact with the cardiac muscle cells via gap junctions

Contractility

the strength of contraction at any given end-diastolic volume

Coronary Arteries

Arteries supplying the myocardium; exit from behind the aortic valve cusps in the very first part of the aorta and lead to a branching network of small arteries, arterioles, capillaries, venules, and veins similar to those in other organs. Most of the cardiac veins drain into a single large vein, the coronary sinus, which empties into the right atrium

Coronary Blood Flow

blood flowing through the coronary arteries

Diastole

alternating period of ventricular relaxation and blood filling

Dicrotic Notch

the rebound of aortic pressure caused by the combination of elastic recoil of the aorta and blood rebounding against the valve

ECG Lead

multiple recording locations on the limbs and chest in order to obtain as much information as possible concerning different areas of the heart

Ejection Fraction (EF)

the ratio of stroke volume to end-diastolic volume; EF=SV/EDV; a way to quantify contractility

Electrocardiogram (ECG)

or EKG, is a tool for evaluating the electrical events within the heart; when AP's occur simultaneously in many individual myocardial cells, currents are conducted through the body fluids around the heart and can be detected by recording electrodes at the surface of the skin

End

Diastole Volume (EDV)- The amount of blood in the ventricle at the end of ventricular diastole

End

Systolic Volume (ESV)- the amount of blood remaining in the ventricle after ejection

Epicardium

A fibrous layer that is closely affixed to the heart; the narrow space between the pericardium and the epicardium is filled with a watery fluid that serves as a lubricant as the heart moves within the sac

Frank

Starling Mechanism- the relationship between stroke volume and end-diastolic volume; The greater the end diastolic volume, the greater the stretch and the more forceful the contraction (length-tension relationship in cardiac muscle)

F

Type Channel- unique set of channels in pacemaker cells that unlike most voltage-gated channels, open when the membrane potential is at negative values. These nonspecific cation channels conduct mainly an inward, depolarizing, Na current and, because of their unusual gating behavior, have been termed "funny"

Heart Rate

the number of times the heart contracts per minute

Heart Sounds

"lub" (closure of AV valves) and "dup" (closure of aortic and pulmonary valves) sounds resulting from cardiac contraction that are heard through a stethoscope placed on the chest wall

Internodal Pathway

pathway of the action potential that is conducted rapidly from the SA node to the AV node

Interventricular Septum

A muscular wall that separates the two ventricles

Isovolumetric Ventricular Contraction

during the first part of systole, the ventricles are contracting but all valves in the heart are closed and so no blood can be ejected; ventricular volume is constant

Isovolumetric Ventricular Relaxation

During the first part of diastole, the ventricles begin to relax and the aortic and pulmonary valves close. At this time, the AV valves are also closed; therefore, no blood is entering or leaving the ventricles and ventricular volume is constant

Laminar Flow

how blood flows normally through valves and vessels in smooth concentric layers

L

Type Ca Channel- modified versions of the dihydropyridine (DHP) receptors that function as voltage sensors in excitation-contraction coupling of skeletal muscle

Mitral Valve

another name for the bicuspid valve, resembles a bishop's headgear (a "mitre")

Myocardium

the wall of the heart composed of cardiac muscle cells

Pacemaker Potential

gradual depolarization; brings the membrane potential to threshold, at which point an AP occurs

Pericardium

a protective fibrous sac that encloses the heart

Preload

the volume of blood in the ventricles just before contraction

Pulmonary Valve

opening of the right ventricle into the pulmonary trunk ("dub" sound)

Purkinje Fiber

large-diameter conducting cells that rapidly distribute the impulse throughout much of the ventricles; make contact with ventricular myocardial cells, which spread the action potential through the rest of the ventricles

P Wave

the first deflection that corresponds to current flow during atrial depolarization

QRS Complex

the second deflection, occurring approx. 1.5 seconds after the P wave; a result of ventricular depolarization

Sinoatrial (SA) Node

The initial depolarization normally arises in this small group of conducting-system cells; located in the right atrium near the entrance of the superior vena cava; normally the pacemaker for the entire heart because its depolarization generates the action potential that leads to depolarization of all other cardiac muscle cells.

Stroke Volume (SV)

The volume of blood ejected from each ventricle during systole. SV=EDV-ESV

Systole

the period of ventricular contraction and blood ejection

Tricuspid Valve

the right AV valve

T

Type Ca Channel- the third type of pacemaker channel that opens briefly but contributes inward Ca current and an important final depolarizing boost to the pacemaker potential

T Wave

the third and final deflection; result of ventricular repolarization

Venous Return

the flow of blood from the veins into the heart

Ventricular Ejection

Once the increasing pressure in the ventricles exceeds that in the aorta and pulmonary trunk, the aortic and pulmonary valves open; blood is forced into the aorta and pulmonary trunk as the contracting ventricular muscle fibers shorten.

Ventricular Filling

when the AV valves open and blood flows into the ventricles from the atria; approx. 80% of ventricular filling occurs before atrial contraction

Ventricular

Function Curve- a graphical representation showing that the mechanical properties of cardiac muscle that form the basis for an inherent mechanism for altering the strength of contraction and stroke volume; the ventricle contracts more forcefully during systole when it has been filled to a greater degree during diastole. In other words, all other factors being equal, the stroke volume increases as the end-diastolic volume increases

Artificial Pacemaker

current treatment for severe AV conduction disorders, as well as for many other abnormal rhythms; a permanent surgical implantation that electrically stimulates the ventricular cells at a normal rate

Atrial Fibrillation

a state in which the cells of the atria contract in a completely uncoordinated manner and so the atria fail to work as effective pumps

AV Conduction Disorders

drug- or disease-induced malfunction of the AV node that may reduce or completely eliminate the transmission of AP's from the atria to the ventricles

Cardiac Angiography

requires the temporary threading of a thin, flexible tube called a catheter through an artery or vein into the heart. A liquid containg radiopaque contrast material is then injected through the catheter during high-speed x-ray videography. Useful for evaluatin cardiac function and identifying narrowed coronary arteries

Echocardiography

used to obtain two- and three-dimensional images of the heart throughout the entire cardiac cycle; ultrasonic waves are beamed through the heart and returning echoes are electronically plotted by computer to produce continuous images of the heart. Can be used to detect abnormal functioning of cardiac valves or contractions of cardiac walls, and it can also be used to measure ejection fraction

Ectopic Pacemaker

other pacemaker cells that are driven to threshold by action potentials from the SA node and do not manifest their own rhythm; have slower inherent pacemaker rates

Heart Murmur

abnormal sounds of the heart that may signify heart disease

Insufficiency

leaky valve

Prolapse

when the AV valves are pushed up and open backward into the atria when the ventricles are contracting

Septal Defect

a small hole in the walls separating the two atria or ventricles

Stenosis

abnormally narrowed valve

Active Hyperemia

increased blood flow when metabolic activity is increased

Angiogenesis

how capillaries develop and grow

Angiogenic Factors

stimulate vascular endothelial cells to build new capillary networks by cell locomotion and cell division

Angiotensin II

hormone important for arteriolar control which constricts most arterioles

Atrial Natriuretic Peptide

secreted by the cardiac atria; potent vasodilator; regulates Na balance and blood volume

Colloid

plasma proteins that are unable to move through capillary pores, have low concentration in interstitial fluid leading to lower water concentration in plasma than in the interstitial fluid creating an osmotic force that tends to cause the flow of water from the interstitial compartment into the capillary

Compliance

how easily a structure stretches; Compliance= Change in Vol./ Change in Pressure. Greater compliance = more easily stretched

Crystalloid

low-molecular weight solutes found in large quantities in plasma within the capillary and the interstitial fluid outside that pass easily through the capillary wall; concentrations of these substances including Na, Cl, and K are nearly identical in capillaries and interstitial fluid

Diastolic Pressure (DP)

the minimum arterial pressure that occurs just before ventricular ejection begins

Endothelin

1 (ET-1)- one of the important vasoconstrictor paracrine agents that the endothelial cells release in response to certain mechanical and chemical stimuli. Can also function as a hormone when blood concentrations are high enough, causing widespread arteriolar vasoconstriction

Flow Autoregulation

when the change in resistance is in the direction of maintaining blood flow nearly constant despite the pressure change

Fused

Vesicle Channels- endothelial cells containing large numbers of endocytotic and exocytotic vesicles that sometimes fuse together

Hyperemia

increased blood flow

Intercellular Clefts

narrow, water-filled spaces that separate the flat cells that constitute the endothelial wall of a capillary

Intrinsic Tone

spontaneous contractile activity of arteriolar smooth muscle (basal tone)

Korotkoff's Sounds

vibrations produced by turbulent high-velocity blood flow through partially compressed arteries when cuff pressure decreases

Local Control

mechanisms independent of nerves or hormones by which organs and tissues alter their own arteriolar resistances, thereby self-regulating their blood flows

Lymph

a fluid derived from interstitial fluid

Mean Arterial Pressure (MAP)

the average pressure during the cardiac cycle

Metarteriole

connect arterioles to venules in which some tissues and organs receive blood to their capillaries

Myogenic Response

direct response of arteriolar smooth muscle to stretch

Net Filtration Pressure (NFP)

depends on 4 variables: capillary hydrostatic pressure, interstitial hydrostatic pressure, osmotic force due to plasma protein concentration, and the osmotic force due to interstitial fluid protein concentration

Precapillary Sphincter

the site at which a capillary exits from a metarteriole; relaxes or contracts in response to local metabolic factors

Prostacyclin

vasodilator released by endothelial cells