Presentation on theme: "Chapter 17 Control of Cardiovascular Function"— Presentation transcript:
1Chapter 17 Control of Cardiovascular Function Essentials of PathophysiologyChapter 17 Control of Cardiovascular Function
2PRE LECTURE QUIZ (TRUE/FALSE) The left side of the heart pumps blood to the lungs. The venous side of the circulation contains a larger portion of the blood volume than the arterial side. The rate of blood flow through a vessel is affected by pressure, resistance, and vessel radius. The loose-fitting sac that surrounds the heart is called the myocardium. The rhythmic impulse of the cardiac conduction system is generated at the AV node and is known as the pacemaker of the heart.FT
3PRE LECTURE QUIZDiastolicFibrillationoutputTricuspidveins_______________ is the result of disorganized electrical activity in the atrium or the ventricle.Cardiac _______________ is the amount of blood the heart pumps each minute and is defined by the formula SV × HR.The _______________ are thin-walled, distensible, and collapsible vessels that are capable of enlarging and storing large quantities of blood.The ______________ period of the cardiac cycle is marked by ventricular relaxation and filling.The heart valve that controls the direction of blood flow from the right atrium to the right ventricle is called the _________________ valve.
4Path of Blood Flow Scenario: You inject a medication into the client’s armWithin a few minutes, some of that drug has reached the client’s liver and is being deactivatedQuestion:How did it get there?
5Simplified Path of Blood Flow bodyleftrightheartheartlungs
7QuestionTrue or False. The pulmonary circulation moves blood through the left side of the heart.
8AnswerFalse Rationale: The right side of the heart pumps blood to the lungs through the pulmonary arteries, where gas exchange takes place. The left side of the heart is considered systemic circulation because blood is pumped to all body tissues.
10The Basics of Cell Firing Cells begin with a negative charge: resting membrane potentialStimulus causes some Na+ channels to openNa+ diffuses in, making the cell more positive (less Negative)Threshold potentialResting membrane potentialStimulus
11The Basics of Cell Firing (cont.) Action potentialAt threshold potential, more Na+ channels openNa+ rushes in, making the cell very positive: depolarizationAction potential: the cell responds (e.g., by contracting)Threshold potentialResting membrane potentialStimulus
12The Basics of Cell Firing (cont.) Action potentialK+ channels openK+ diffuses out, making the cell negative again: repolarizationNa+/K+ ATPase removes the Na+ from the cell and pumps the K+ back inThreshold potentialResting membrane potentialStimulus
13Cardiac Muscle FiringCells begin with a negative charge: resting membrane potentialCalcium leak lets Ca2+ diffuse in, making the cell more positiveThreshold potentialResting membrane potentialCalcium leak
14Cardiac Muscle Firing (cont.) Action potentialAt threshold potential, more Na+ channels openNa+ rushes in, making the cell very positive: depolarizationAction potential: the cell responds (e.g., by contracting)Threshold potentialResting membrane potentialCalcium leak
15Cardiac Muscle Firing (cont.) K+ channels openK+ diffuses out, making the cell negative again, but Ca2+ channels are still allowing Ca2+ to enterThe cell remains positive: plateauAction potentialPLATEAUThreshold potentialCalcium leak
16Cardiac Muscle Firing (cont.) During plateau, the muscle contracts stronglyThen the Ca2+ channels shut and it repolarizesAction potentialPLATEAUThreshold potentialCalcium leak
17QuestionWhich ion channels allow cardiac muscle to fire without a stimulus?Na+K+Ca2+Cl-
18AnswerCa2+Rationale: In the SA and AV nodes, resting cardiac muscle cells have open Ca2+ channels. This allows Ca2+ to leak into the cells, making them more positive (the cells reach threshold this way without the need for a stimulus).
19The Cell Passes the Impulse to Its Neighbors Desmosomes link cells tightly togetherGap junctions pass the electrical signal to the next cells
20Heart ContractionHow would each of the following affect heart contraction:A calcium channel blockerAn Na+ channel blockerA drug that opened Na+ channelsA drug that opened K+ channels
21Cardiac Cycle—Diastole Ventricles relaxBlood entering atriaBlood flows through AV valves into ventriclesSemilunar valves are closed
23Cardiac Cycle—Systole Ventricles contractBlood pushes against AV valves and they shutBlood pushes through semilunar valves into aorta and pulmonary trunk
24What happens in isovolumetric contraction? SystoleWhat happens in isovolumetric contraction?
25QuestionWhich of the following statements is true about ventricular systole?Atria contractVentricles contractAV valves are openSemilunar valves are closed
26AnswerVentricles contractRationale: During ventricular systole, the ventricles contract. Because blood is being forced from the ventricles, semilunar valves must be open and AV valves closed. The atria are in diastole (relaxation) during ventricular systole.
27Cardiac Cycle Discussion: Arrange these steps in the proper order: 8– Ventricles relax 4– First heart sound1– Systole 5– Semilunar valves open10–Diastole 3– AV valves close9– AV valves open 6– Semilunar valves close2– Ventricles contract 7– Second heart sound
28Pressure, Resistance, Flow Fluid flow through a vessel depends on:The pressure difference between ends of the vesselPressure pushes the fluid throughPressure keeps the vessel from collapsingThe vessel’s resistance (R) to fluid flowSmall vessels have more resistanceMore viscous fluids have greater resistanceΔP = Pin - PoutFlow, F= ΔP ÷ R
29Pressure, Resistance, Flow of Blood Blood flow through a vessel depends on:Heart creating pressure difference between ends of the vesselHeart pushing the blood throughBlood pressure keeping the vessels openThe vessel’s resistance to fluid flowConstricting arterioles increasing resistanceIncreased hematocrit increasing resistance
30DiscussionHow will each of these factors affect arteriole size and peripheral resistance?Lactic acid • Low PO2Cold • HistamineEndothelin • HeatNO • Adenosine
31Blood pressure = cardiac output × peripheral resistance BP = CO x PRBlood pressure = cardiac output × peripheral resistanceHow is this related to F=P/R ?
32QuestionTell whether the following statement is true or false. In patients with hypertension (high blood pressure), peripheral resistance is increased. (Hint: P= F x R )
33AnswerTrue Rationale: In hypertension, blood vessels are constricted/narrowed. Smaller vessels increase resistance (it’s harder to push the same amount of fluid/blood through a tube that has become smaller).
34Forces Moving Fluid In and Out of Capillaries Higher Pressure from arteryLower Pressure of the veins
35Lymph Vessels Carry Tissue Fluid Back to the Veins Interstitial fluid not recaptured in the capillaries enters the lymphatic system and ultimately reenters the blood at the subclavian vein