Anim cardiac output worksheet PDF

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Cardiac Output Instructions: please answer the questions below.

1. a. Define cardiac output and explain how it is calculated. cardiac output maintains blood flow throughout body. It is the measure of blood volume ejected from the heart over a given time. Determined by multiplying heart rate by stroke volume. b. What is normal cardiac output? About 5 liters per minute.

2. How does exercise affect cardiac output? mild exercise will double cardiac output but vigorous exercise can be as much as 20 l/min.

3. a. Explain how the End Diastolic Volume (EDV) and the End Systolic Volume (ESV) produce the Stroke Volume (SV). Stroke volume represents the difference in the amount of blood between the volume in the ventricles at the end of diastole and the volume after systole. .

b. How much is normal stroke volume? 70 ml

4. The following three factors affect stroke volume. Define each. a. Preload - the amount of stretch of ventricular muscle before the contraction starts

b. Contractility - the forcefulness of ventricular muscle contraction

c. Afterload - the pressure that must be overcome before ventricles can eject blood © John Wiley & Sons, Inc. or the author, All rights reserved. No part of these materials should be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse this material is available at http://www.wiley.com/go/permissions.

5. Describe how End Diastolic Volume (EDV) affects the degree of cardiac muscle stretch, known as preload. Increased return blood flow from the veins increases end-diastolic volume. Cardiac muscle sarcomeres stretch and lengthen.

6. Explain how sarcomere stretch and contraction strength affects stroke volume. Contraction of the cardiac muscle sarcomeres during ventricular systole provides the force needed to eject blood from the heart. Increased muscle stretch increases tension and a more forceful contraction ejects more blood, increasing stroke volume.

7. a. Explain the Frank-Starling Law. The greater the preload, the greater the sarcomere stretch, the greater the stroke volume. b. What are the limits of the Frank-Starling Law? When cardiac muscle is overstretched, increasing ventricular filling has no significant effect on stroke volume.

8. a. Contrast the affects of positive and negative inotropic agents on stroke volume and cardiac output. Positive inotropic agents increase contractility and will increase stroke volume and cardiac output. Negative inotropic agents reduce force of contraction.

b. Name specific types of inotropic agents. Positive - neurotransmitters (norepinephrine), hormones (epinephrine and thyroxine) & drugs (digoxin) Negative - calcium channel blockers, some anesthetics

9. How does ventricular pressure and afterload affect activity of the semilunar valve? © John Wiley & Sons, Inc. or the author, All rights reserved. No part of these materials should be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse this material is available at http://www.wiley.com/go/permissions.

The left ventricle blood pressure must overcome arterial pressure in the aorta.

10. a. How does high blood pressure or hypertension affect aortic pressure? Hypertension increases aortic pressure, which must be overcome by higher left ventricular pressure.

© John Wiley & Sons, Inc. or the author, All rights reserved. No part of these materials should be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse this material is available at http://www.wiley.com/go/permissions.

b. Eventually, ventricular pressure will build and overcome aortic pressure thereby opening the semilunar valve and ejecting the blood. How does increased afterload affect ejection and stroke volume? Increased afterload makes ejection more difficult and decreases stroke volume and cardiac output.

How does the heart adjust to maintain homeostasis? When afterload decreases the cardiac output, other mechanisms help bring it back to normal. Preload is increased via feedback mechanisms and contractility is increased.

11. a. What initiates the 60-100 (75 normal resting) heartbeats per minute? SA node b. Describe the correlation between cardiac output and heart rate. Cardiac output is directly proportional to heart rate, the greater the heart rate, the greater the cardiac output

12. Describe the sympathetic nervous system and hormonal responses to low blood pressure. How does this response contribute to maintaining homeostasis? Situations that decrease blood pressure promote sympathetic stimulation and the release of norepinephrine, which increases heart rate and cardiac output.

13. Describe the parasympathetic nervous system and hormonal responses to high blood pressure. How does this response contribute to maintaining homeostasis? Situations that increase blood pressure promote parasympathetic stimulation and the release of acetylcholine, which decreases heart rate and cardiac output.

14. What affect do epinephrine, norepinephrine, and thyroxine have on heart rate? Accelerate heart rate © John Wiley & Sons, Inc. or the author, All rights reserved. No part of these materials should be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse this material is available at http://www.wiley.com/go/permissions.

15. How does low blood O2 and pH, high blood CO2, and increasing cytosolic Ca++ affect heart rate? Trigger an increased heart rate

© John Wiley & Sons, Inc. or the author, All rights reserved. No part of these materials should be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse this material is available at http://www.wiley.com/go/permissions....