Exam 2 - Cardiovascular System (pt. 2)

Question 1

What are the characteristics of neurons?

Answer 1

• lipid bilayer membrane is impermeable to ions
• ions must pass through ion channels
• ion channels are sensitive to environment and can change shape

Question 2

What is the resting membrane potential?

Answer 2

approximately -70 mV

Question 3

What are voltage-gated ion channels?

Answer 3

ion channels that change structure in response to voltage changes

Question 4

What are leak channels?

Answer 4

• channels that are generally open but may open and close at random
• no actual event that opens the channel; intrinsic rate of switching between open and closed

Question 5

How is the Na+ and K+ gradient maintained?

Answer 5

active transport via the Na+/K+ pump

Question 6

What are the steps of an action potential/

Answer 6

1. at rest
2. stimulus applied
3. voltage rises
4. voltage falls
5. end of action potential
6. return to rest

Question 7

Which nodes are responsible for maintaining heart beat?

Answer 7

• sinoatrial (SA) node

- atrioventricular (AV) node

Question 8

What are pacemaker cells?

Answer 8

cells at the SA node that coordinate the heartbeat

Question 9

Why does the SA node only control atrial excitation and contraction?

Answer 9

the fibrous skeleton prevents the electrical signal from entering the ventricles

Question 10

What is the role of the AV node?

Answer 10

to serve as the “electrical gateway” into the ventricles and conduct the action potential

Question 11

What is the role of purkinje fibers?

Answer 11

conduct the action potential to the muscle cells of the ventricle walls

Question 12

What events occur during contraction?

Answer 12

• cells of SA node trigger action potential
• action potential moves through the two atria, causing atrial systole
• action potential depolarizes cells of the AV node, causing ventricular systole
• action potential is propagated down AV bundle cells and Purkinje cells
• action potential propagated throughout ventricles, causing contraction from the bottom up

Question 13

What does an ECG measure?

Answer 13

small changes in voltage between the heart and the rest of the body

Question 14

What are the waves of an ECG and what do they correspond to?

Answer 14

• P wave: atrial depolarization
• QRS complex: ventricular depolarization, atrial repolarization
• T wave: ventricular repolarization

Question 15

What type of procedure can remedy a lack of SA node activity/

Answer 15

pacemaker insertion

Question 16

What is systolic pressure?

Answer 16

the blood pressure during ventricular systole

Question 17

What is diastolic pressure?

Answer 17

the blood pressure during ventricular diastole

Question 18

Why are arteries thicker than veins?

Answer 18

there is greater pressure in the arteries than in the veins

Question 19

How is blood flow regulated?

Answer 19

• vasoconstriction

- vasodilation

Question 20

What is cardiac output?

Answer 20

amount of blood pumped by the left ventricle in one minute

Question 21

What three variables affect blood pressure?

Answer 21

• cardiac output
• resistance of vessels
• blood volume

Question 22

What are included in the cardiovascular control centers in the brain?

Answer 22

• cardioacceleratory neurons
• cardioinhibitory neurons
• vasomotor control

Question 23

What is the sympathetic response?

Answer 23

• occurs when blood pressure is too low

- causes increased heart rate and vasoconstriction

Question 24

What is the parasympathetic response?

Answer 24

• occurs when blood pressure is too high

- causes decreased heart rate and vasodilation