Midterm Cardiovascular

Question 1

what is the optimal blood pH?

Answer 1

7.35 - 7.45

Question 2

cardiac muscle cells have more ____ than skeletal muscle in order to perform aerobic respiration

Answer 2

mitochondria

Question 3

the heart extracts ___% of oxygen

Answer 3

60-70%

Question 4

ejection fraction of blood at rest (in mL)

Answer 4

~70ml

Question 5

how much does the heart weigh?

Answer 5

275g (female) or 325g (male)

Question 6

the space in the thoracic cavity where the heart is located

Answer 6

mediastinum

Question 7

pleural pressure becomes _____ (+ or -) during inhalation

Answer 7

negative. this promotes blood flow into the heart

Question 8

the apex of the heart lies between the junction of which ribs?

Answer 8

4th and 5th

Question 9

name the septums that divide the: atria and ventricles; right and left sides

Answer 9

atrioventricular; interatrial and interventricular

Question 10

autorhythmicity (in terms of the heart)

Answer 10

Cardiac myocytes have the ability to initiate their own electrical potential at a fixed rate which are able to spread through the gap junctions

Question 11

what are the two major types of cardiac muscle cells, and what percentage do they each occupy?

Answer 11

mycardial contractile cells, 99%

myocardial conducting cells, 1%

Question 12

Normal cardiac rhythm is established by the ____, known as the pacemaker of the heart and initiates sinus rhythm

Answer 12

sinoatrial (SA) node

Question 13

The SA node, without nervous or endocrine control, would initiate an impulse ____ times / min
Without the SA node, the AV node would generate an impulse ____ times /min

Answer 13

~80–100, ~40-60

Question 14

cardiac contractile cells have a long refractory period (~250ms) to allow the ventricles to do what?

Answer 14

fill without fluttering

Question 15

cardiac muscle action potentials are what compared to skeletal muscle?

Answer 15

slower, longer-lasting, with a greater refractory period

Question 16

describe what each point represents:

P wave, QRS complex, T wave

Answer 16

depolarization of the atria (~25ms later), depolarization of the ventricles (peak of R wave), repolarization of the ventricles

Question 17

why is atrial repolarization not seen on an ECG?

Answer 17

masked by the QRS complex

Question 18

which ventricle generates a higher pressure when ejecting blood?

Answer 18

left; 80 mmHg compared to 8-20 mmHg in the right

Question 19

cardiac output is equal to ___ x ___

Answer 19

stroke volume x heart rate

Question 20

3 main factors contributing to stroke volume

Answer 20

preload, contractility, afterload

Question 21

Frank-Starling Mechanism / Law

Answer 21

• force of heart contraction is proportional to the initial length of the muscle fiber.
• the greater the stretch of the ventricular muscle (within limits), the more powerful the contraction is, which in turn increases SV.
• by increasing preload, you increase the second variable, contractility

Question 22

autonomic nervous system effects on heart rate:

Answer 22

Down regulation via Parasympathetic (Vagus) input

Up regulation via Sympathetic input
-Norepinephrine shortens the repolarization period

Question 23

endocrine control of heart rate

Answer 23

• Adrenal medulla releases epinephrine and thyroid releases thyroid hormones which both act to increase HR
• Increased levels of K+ or Na+ decrease HR

Question 24

maximum cardiac output (trained and untrained)

Answer 24

~35L/min (highly trained), ~20-25L/min (untrained)