Lesson 10: Blood Pressure and Heartbeat

Question 1

how long do these heartbeats take under normal conditions?

Answer 1

0.8s

Question 1

what is a cardiac cycle? what does it involve?

Answer 1

the process of a complete heartbeat; this involves a full contraction and relaxation of each chamber of the heart

Question 2

how many phases is the cardiac cycle divided into? what are these phases?

Answer 2

2 phases
- diastole phase (when the heart is relaxed and filling with blood)
- systole phase (when the heart contracts and is emptying)

Question 3

what is the heart’s sound caused by? what is happening in each part of the sound (lub and dub)?

Answer 3

caused by the opening and closing of heart valves; sounds like “lub-dub”
- the first part (lub) occurs when the atrioventricular valves closed and the ventricles begin to contract
- the second part (dub) occurs when the ventricles relax and the semilunar valves snap shut

Question 4

stethoscope

Answer 4

• helps you hear your heartbeat
• if the heartbeat sounds are not normal, this may be a sign of a leaking valve, also known as a heart murmur

Question 5

what is the myogenic muscle? what is its ability?

Answer 5

the heart muscle; it has to ability to contract and relax on its own without stimulation from nerves

Question 6

how come an organism’s heart can still beat even though they have a damaged nervous system?

Answer 6

due to the mygenic muscle

Question 7

what is the sinoatrial node (SA)?

Answer 7

the contraction that initiates the heartbeat, and is from a cluster or group of cells in the right atrium

Question 8

what does the SA do (sinoatrial node)? what does it act as?

Answer 8

the cluster of cells sends an electrical signal which causes the atria to contract; it acts as a pacemaker (its responsible for setting a normal rhythm of the heartbeat, and determines heart rate)

Question 9

what is the atrioventricular node (AV)?

Answer 9

it is located on the other side of the right atrium meartructure where the electrical signal then propagates or spreads to a group of cells in between of the right atrium and ventricle

Question 10

what does the atrioventricular node (AV) do? what happens after this happens?

Answer 10

this cluster of cells sends an electrical signal through special conductive fibers called purkinje fibers; it serves as an electrical gateway to the ventricles, and delays the passage of electrical impulses to the ventricles (delay happens to ensure that the atria ejected all the blood into the ventricles before the ventricles contract)
- the AV node receives signals from the SA node, and passes them onto the atrioventricular bundle

Question 11

what is the atrioventricular bundle? what happens next?

Answer 11

it is a bundle divided into right and left bundle branches, which conduct the impulses towards the apex of the heart- the signals are then passed to Purkinje fibers, turning upward and spreading throughout the ventricular myocardium

Question 12

what is electrocardiogram? what are they used for?

Answer 12

where electrical activities of the heart is recorded (called ECG or EKG); they are used to observe the heart by measuring length and strength of the electrical signals

Question 13

what can you do if theres an abnormality in the heart?

Answer 13

ECG (electrocardiogram) can provide doctors with information

Question 14

what is blood pressure? how is it measured? why is blood always under pressure?

Answer 14

Blood pressure is the pressure your blood exerts on the walls of the circulatory system
- Blood is always under pressure in the blood vessels because of the contractions from your heart
- Pressure increases when your heart is contracting and decreases when your heart relaxes

Question 15

what happens when the amount of blood in our blood vessels increase (specifically about the pressure)?

Answer 15

If the amount of blood increases, so does the force on the walls of the blood vessels (this essentially increases the pressure)

Question 16

what happens when theres too much pressure on the blood vessels?

Answer 16

Hypotension or hypertension- it can lead to serious health risks (strokes, heart attacks, etc)

Question 17

what is a sphygmomanometer?

Answer 17

an instrument that measures your blood pressure

Question 18

how does a sphygmomanometer work?

Answer 18

• cuff is wrapped around the arm and measured the pressure of the blood in your BRACHIAL ARTERY

Question 19

what is the brachial artery?

Answer 19

the major blood vessel supplying blood to your upper arm/forearm

Question 20

what does the sphygmomanometer measure (what 2 things)? explain each.

Answer 20

• your systolic pressure (pressure when your heart is contracting)
• diastolic pressure (pressure when your heart is relaxed)

Question 21

what is the unit of measurement for blood pressure

Answer 21

millimetres of mercury (mm Hg)

Question 22

what should a normal blood pressure of a healthy young adult look like?

Answer 22

systolic pressure of 120 mm Hg; diastolic pressure of 80 mm Hg

Question 23

what does the pressure do as it moves away from the heart?

Answer 23

the pressure will decrease slowly as it moves away from the heart (the pressure in the vessels closest to your heart will basically be the highest)

Question 24

describe/explain the systolic phase?

Answer 24

the heart contracts, blood pressure rises and blood moves out along the vessels

Question 25

describe/explain the diastolic phase

Answer 25

the heart relaxes, blood pressure falls and the blood fills the heart

Question 26

when is blood pressure highest?

Answer 26

during systole, when heart contracts to force blood through the arteries

Question 26

when is blood pressure at its lowest value?

Answer 26

when the heart is at rest between beats: the diastolic pressure

Question 27

when does a heart attack occur?

Answer 27

when oxygen-deprived cardiac muscle cells start to die

Question 28

why is there a delay between the transfer of SA node and AV node?

Answer 28

to ensure that the atria has ejected all of the blood into the ventricles before the ventricles contract