Lecture 11

Question 1

What are responsible for the heart contracting?

Answer 1

Cardiomyocytes

Question 2

Cardiomyocytes can contract without a

Answer 2

Connection to the nervous system

Question 3

Where are the APs for heart contraction coming from?

Answer 3

They are generated by the Cardiomyocytes themselves

Question 4

Hearts have a specialized group of cells called

Answer 4

Pacemaker Cells

Question 5

Pacemaker cells function to

Answer 5

Create APs that cause different chambers of the heart to contract

Question 6

Why are Pacemaker Cells able to generate APs?

Answer 6

They have unstable resting membrane potentials

Question 7

The unstable resting membrane potentials for Pacemaker cells are caused by?

Answer 7

Sodium channels called Funny channels

Question 8

When do Funny Channels open?

Answer 8

During hyperpolarization and allow Na+ to enter the cell until the threshold is crossed and an AP occurs

Question 9

Pacemaker cells are grouped together in the

Answer 9

SA Node

Question 10

Pacemaker cells have the same three phases of AP, but they

Answer 10

Deal with Ca2+ ions instead of Na+ ions

Question 11

What happens during Depolarization in Pacemaker cells?

Answer 11

Voltage-gated Ca2+ channels open and Ca2+ enters the cell

Question 12

What ion causes for muscle contraction in the heart?

Answer 12

Ca2+

Question 13

Voltage-gated Ca2+ channels open when

Answer 13

The threshold potential has been crossed in the pacemaker cells by funny channels and sodium entering the pacemaker cells

Question 14

APs generated in the pacemaker cells cause muscle cells in the two atria to

Answer 14

Contract at the same time

Question 15

The AP spreads across the muscle cells in the two atria until it reaches the

Answer 15

AV Node

Question 16

What does the AV node function to do?

Answer 16

Delays the AP before it reaches the muscle cells in the ventricles, allowing the ventricles to contract after the atria

Question 17

Heart pumps blood through the arteries via the

Answer 17

Systemic circuit

Question 18

Arteries near the heart have a

Answer 18

Thicker tunica externa

Question 19

A thicker tunica externa is composed of

Answer 19

Collagen fibers that strengthen the vessel to withstand this added force

Question 20

Fluctuations in BP are a result of

Answer 20

Heart contractions

Question 21

The speed at which blood is traveling is greatest in the

Answer 21

Left ventricle

Question 22

Capillaries lack both a

Answer 22

Tunica externa and tunica media

Question 23

How is the Tunica Intima in capillaries?

Answer 23

An extremely thin and porous

Question 24

Blood moves the slowest in the

Answer 24

Capillaries

Question 25

Differences in permeability are caused by

Answer 25

The fenestrations in the tunica intima

Question 26

Continuous Capillaries are most commonly found in

Answer 26

Vertebrate circulatory systems and in muscle and lung tissue

Question 27

What is the function of Continuous Capillaries?

Answer 27

They allow gas exchange to occur between the blood and lungs + deliver oxygen to muscles that use a lot of oxygen

Question 28

Fenestrated Capillaries can be found in

Answer 28

The glomerulus of the kidneys, allowing kidney to filter blood

Question 29

Describe Fenestrated Capillaries

Answer 29

Larger pores allow water, ions, and other small molecules to move into the kidneys

Question 30

Sinusoidal Capillaries are

Answer 30

Extremely Porous

Question 31

Sinusoidal Capillaries are found in the

Answer 31

Bone marrow

Question 32

Veins have a

Answer 32

Thinner tunica externa