Cardiovascular System 2

Question 1

why don’t all cardiac muscles need a nerve to contract?

Answer 1

because of the intertwining look

when 1 section of cardiac muscle contracts it stimulate whole muscle

Question 2

what is a pacemaker?

Answer 2

clectrical signal to beat every 1/4 second = control of the heart beat

Question 3

where is the pacemaker located?

Answer 3

in the right atrium

Question 4

what are the steps to control the heartbeat?

Answer 4

1) pacemaker generates a signal to contract, spreading to both atria
2) both atria contract simultaneously
- signal from SA node stimulates AV node
3) AV fires and transfers through branches to apex of heart
4) ventricle contraction starts at apex and spreads to rest of ventricle via purkinue fibres

Question 5

what is the cardiac conduction system ?

Answer 5

a collection of nodes and specialised conduction cells that initiate and co-ordinate contraction of the heart muscle

Question 6

what does the conduction system consist of?

Answer 6

1) sinoatrial node (SA node)
2) atrioventricular node (AV node)
3) atrioventricular bundle (AV bundle)
4) Purkinje fibres (deep in ventricles)

Question 7

what is involved in the pumping action (heart beat)?

Answer 7

• periods of contraction (systole)

alternating with

• periods of relaxation (diastole)

Question 8

what is systole?

Answer 8

periods of contraction when the heart beats

Question 9

what is diastole?

Answer 9

periods of relaxation when the heart beats

Question 10

what is a cardiac cycle?

Answer 10

the continual rhythmical contraction and relaxation of the heart

each cycle takes approx 1 second

Question 11

what is the sound we hear when using a stethascope?

Answer 11

the valves closing

Question 12

what does a single heart beat involve?

Answer 12

1) contraction/relaxation of both atria
2) contraction/relaxation of both ventricles

Question 13

describe the cardiac cycle

Answer 13

1) all 4 chambers are relaxed (diastole)
- semilunar valves close to prevent backflow “dubb” sound
2) atrial systole/ventricular diastole
- atrial contraction forces blood into ventricles, filling/stretching them
3) ventricular systole/atrial diastole
- atria relaxes and begins to fill with blood flowing from veins
4) ventricles contract, increased pressure forces AV valves closed “lubb” sound
5) blood is forced through semilunar valves into the arteries

Question 14

what is an electrocardiogram (ECG)?

Answer 14

recording electrical activity and charting it

AKA getting heatr pattern

Question 15

what is the sequence of depolarization/repolarization of the heart of an ECG tracing?

Answer 15

1) atrial depolarization initiated by SA node causes P wave
2) impulse delayed at the AV node
3) ventricular depolarization begins at apex (QRS complex)
4) venticular depolarization is complete
5) ventricular repolarization begins at apex (T wave)
6) ventricular repolarization is complete

Question 16

what control does the heart have for beating?

Answer 16

intrinsic

Question 17

what other factors influence heart rate?

Answer 17

1) autonomic nervous system
ex: change in blood pressure

O2/CO2 levels

2) chemical regulation
ex: hormones, ionic blood composition
3) body temperature
ex: elevated = increase HR

lower = decrease HR

Question 18

what is the structure of blood vessels?

Answer 18

ARTERIES

1) tunica externa
2) tunica media
3) tunica interior
4) thick layer of muscle
5) thick layer of elastic connective tissue

VEINS

1) valves
2) thinner layer of muscle

CAPILLARIES

• pickup waste products

Question 19

what is the structure of artery and vein?

Answer 19

• squamous endothelial cells
• layer of smooth muscle
• elastic connective tissue
• valve in veins

Question 20

what is the structure of a capillary?

Answer 20

• extremely thin blood vessels
• only one cell can pass at a time for most
• 3 different types called “continuous capillaries”

Question 21

what are capillilary leaks?

Answer 21

when some plasma leaves the blood

Question 22

what is blood pressure?

Answer 22

the pressure exerted on the arterial walls due to contraction of the ventricles

Question 23

what are the 2 readings we get with blood pressure?

Answer 23

1) systolic pressure (ventricle contaction)
2) dyastolic pressure (ventricle relaxation)

Question 24

what is the normal average resting values for blood pressure?

Answer 24

male 120/80 mmHg

Female = 7-10 mmHg lower

Question 25

what are some factors that affect blood pressure?

Answer 25

1) heart rate
2) strength of contraction
3) blood volume
4) blood vessel resistance (diameter of blood vessel)
5) blood viscosity (thickness

Question 26

where in the body can the pulse be felt?

Answer 26

1) radial artery
2) cartoid artery
3) temporal artery
4) femoral artery