Blood Pressure and Heartbeat (lesson ten)

Question 1

what is a cardiac cycle

Answer 1

• A complete heartbeat is called a cardiac cycle
• This involves a full contraction and relaxation of each chamber of the heart
• The cardiac cycle is usually divided into two basic phases

Question 2

what are the two phases of the cardiac cycle?

Answer 2

• The diastole phase, when the heart is relaxed and filling with blood
• The systole phase, when the heart contracts and empties

Question 3

why does a heart make a “lubb-DUBB” sound?

Answer 3

• The “lubb” occurs when the atrioventricular valves close and the ventricles begin to contract
• The “DUBB” occurs when the ventricles relax and the semilunar valves snap shut

Question 4

sinoatrial (SA) node

Answer 4

• The contraction that initiates the heartbeat is from a cluster/group of cells in the right atrium called the sinoatrial (SA) node
• This cluster of cells sends an electrical signal which causes the atria to contract
• The SA node can generate b/w 50-100 electrical signals per minute
• The SA node acts as a pacemaker - its signals are responsible for setting a normal rhythm of the heartbeat

Question 5

atrioventricular (AV) node

Answer 5

• The electrical signal then propagates (i.e. “spreads”) to a group of cells in between the right atrium and ventricle called the atrioventricular (AV) node
• This cluster of cells sends an electrical signal through special conductive fibres called purkinje fibres
• This signal is passed down the septum and causes the ventricles to contract

Question 6

how can a heart be observed?

Answer 6

• Because the heart is electrically stimulated, it can be observed by measuring the length and strength of electrical signals

Question 7

what tool is used to measure the length and strength of electrical signals?

Answer 7

• The tool used is called an electrocardiograph, which produces an electrocardiogram (ECG)
• If the heart is abnormal, an ECG can provide doctors with information

Question 8

Blood Pressure

Answer 8

• 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
• The pressure your blood exerts on the walls of the circulatory system is what we call blood pressure

Question 9

what happens if the amount of blood increases?

Answer 9

If the amount of blood increases, so does the force on the walls of the blood vessels and therefore so does the pressure

Question 10

what happens if there is too much pressure on your blood vessels?

Answer 10

Too much pressure on the vessels can lead to serious health risks

Question 11

sphygmomanometer

Answer 11

• can measure your blood pressure using an instrument called a sphygmomanometer
• The unit of measurement for blood pressure is millimetres of mercury (mm Hg)

Question 12

two things that the sphygmomanometer measures?

Answer 12

• Your systolic pressure, the pressure when your heart is contracting
• Your diastolic pressure, the pressure when your heart is relaxed

Question 13

systolic pressure

Answer 13

the blood pressure in the arteries when the heart contracts

Question 14

diastolic pressure

Answer 14

the blood pressure in the arteries when the heart relaxes

Question 15

what happens to arteries when ventricles contact with to pump?

Answer 15

When the ventricles of the heart contract to pump blood around the body, the arteries expand slightly in diameter to accommodate the increased pressure of the blood within them.

Question 16

vasodilation

Answer 16

The relaxation of the smooth muscle, which increases the diameter of blood vessels, is known as vasodilation.

Question 17

Vasoconstriction

Answer 17

• vasoconstriction is a decrease in the
  diameter of arterioles that decreases the blood flow to tissues

Question 18

venules

Answer 18

• the capillaries merge into small vessels called venules that merge to form larger vessels called veins.
• Venules and veins carry deoxygenated blood containing carbon dioxide and other waste products from the body tissues.
• The one exception is the capillary networks in the lungs, where the blood is oxygenated

Question 19

Hypertension

Answer 19

• Blood pressures consistently above the normal levels constitute a condition called hypertension
• commonly known as high blood pressure

Question 20

The Lymphatic System

Answer 20

The lymphatic system has two major roles: one in the circulatory system and the other in the immune system.

Question 21

lymph

Answer 21

lymph tissue fluid collected in the lymph vessels and returned to the blood

Question 22

lymph node

Answer 22

an enlargement in the lymph vessels that act as a filter to remove bacteria and foreign particles

Question 23

spleen

Answer 23

the largest organ of the lymphatic
system; acts as a filter and a reservoir of erythrocytes and leukocytes

Question 24

thymus

Answer 24

a glandular organ of the lymphatic system; secretes hormones to promote the maturity of lymphocytes