17-2: Pathway of circulation

Question 1

The right atrium receives __ blood through __ pathways: _.

Answer 1

deoxygenated blood; three pathways; superior vena cava, inferior vena cava, coronary sinus

Question 2

superior vena cava

Answer 2

returns deoxy blood from organs above the heart and empties into R atrium

Question 3

inferior vena cava

Answer 3

returns deoxy blood from organs below the heart and empties into R atrium

Question 4

coronary sinus

Answer 4

returns deoxy blood from vessels supplying the myocardium and empties into R atrium

Question 5

The right ventricle receives _ blood from __; then pumps it through _.

Answer 5

deoxy; tricuspid valve; pulmonary SL valve into pulmonary trunk

Question 6

Deoxy blood entering the pulmonary trunk goes: __.

Answer 6

into right and left pulmonary arteries that carry the blood to the lungs, dropping off CO2 and picking up O2

Question 7

The left atrium receives _ blood from __.

Answer 7

oxy blood from the lungs through 4 pulmonary veins

Question 8

The left ventricle receives _ blood from _; then pumps it through _.

Answer 8

oxy; mitral/bicuspid valve; the aortic SL valve into aorta

Question 9

Oxy blood entering the aorta goes _.

Answer 9

into many major arteries supplying all body tissues with oxygen.

Question 10

Which ventricle has thicker walls?

Answer 10

left ventricle - pumping blood to a longer route through the whole body

Question 11

coronary circulation

Answer 11

heart tissues need their own blood vessels, because food and O2 can’t diffuse from blood inside the heart through the myocardium

Question 12

The coronary circulation originates as ___ branches off of the ___.

Answer 12

2 main branches; ascending aorta

Question 13

left coronary artery

Answer 13

runs to left side of heart and divides into two major branches: anterior interventricular artery and circumflex artery

Question 14

right coronary artery

Answer 14

runs to right side of heart and divdes into two major branches: marginal artery and the posterior interventricular artery

Question 15

anterior interventricular artery

Answer 15

branches from the left coronary artery

Question 16

posterior interventricular artery

Answer 16

branches from the right coronary artery

Question 17

marginal artery

Answer 17

branches from the right coronary artery

Question 18

circumflex artery

Answer 18

branches from the left coronary artery

Question 19

As blood delivers O2/nutrients and picks up CO2/waste from the cardiac cells, it is collected by ___ which empty into ___.

Answer 19

cardiac veins; coronary sinus

Question 20

coronary sinus

Answer 20

large vein on posterior surface of the heart where cardiac veins empty; it empties into the right atrium

Question 21

anastomosis

Answer 21

where several arteries supplying the same region merge; these fusing networks provide collateral routes for blood delivery to the myocardium

Question 22

conduction system

Answer 22

internal regulating system of the heart (even out of the body, the heart continues to beat)

Question 23

autorhythmicity

Answer 23

specialized cardiac cells spontaneously and rhythmically generate electrical impulses that stimulate the cardiac muscles to contract (unstable resting potential)

Question 24

syncytia

Answer 24

the cardiac muscle cells are so tightly connected at the intercalated discs, that when 1 fiber is stimulated, they all contract simultaneously as a unit

Question 25

The heart is divided into two syncytia: ___ and ___.

Answer 25

atrial syncytium and ventricular syncytium, separated by a wall of insulating connective tissue

Question 26

The conduction pathway consists of __ regions of ___ cells.

Answer 26

5; autorhythmic

Question 27

sinoatrial node

Answer 27

mass of self excitable cells in the wall of the right atrium, just below opening to SVC

Question 28

pacemaker cells

Answer 28

SA node - these cells set the pace for heart rate because they’re faster than other areas

Question 29

normal sinus rhythem

Answer 29

~75 bpm, but may be altered by nerve impulses from autonomic nervous system or chemicals

Question 30

The impulse generated by the SA node does what?

Answer 30

spreads rapidly over the atrial syncytium, causing the atria to contract simultaneously

Question 31

atrioventricular node

Answer 31

2nd mass of self excitable cells, at the base of the inter atrial septum; last part of atria to depolarize

Question 32

bundle of His

Answer 32

electrical bridge between the atria and ventricles, in the interventricular septem

Question 33

The bundle of His splits __, which terminate into __.

Answer 33

into right and left bundle branches; many Purkinje fibers

Question 34

What causes ventricular contraction?

Answer 34

stimulation of the ventricular syncytium by the Purkinje fibers

Question 35

What are the steps in the conduction pathway?

Answer 35

1. SA node sets the pace;
2. impulse travels through atrial syncythium, causing both atria to contract
3. impulse travels to the AV node
4. impulse travels down the bundle of His and interventricular septum, which branches into right and left bundle branches
5. impulse travels from bundle branches to many Purkinje fibers, which stimulate the ventricular syncythium, causing both ventricles to contract