The Heart And Cardiac Cycle

Question 1

Mass transport systems

Answer 1

Bulk movement of substances through transport systems used to supply materials to all cells in large organisms mass transport system linked with substance exchange systems for example lungs the leaves kidneys the gut the roots

Question 2

The mammalian heart

Answer 2

Arteries carry blood away from heart veins carry blood into the heart valves prevent back flow
2 separate pumps right side pumps to lungs
Left side pumps to body
4 chambers atria and and ventricles

Question 3

Vena cava

Answer 3

Brings deoxygenated blood back from the body

Question 4

Pulmonary artery

Answer 4

Carries deoxygenated blood to lungs

Question 5

Aorta

Answer 5

Carries oxygenated blood to the body

Question 6

Pulmonary vein

Answer 6

Carries oxygenated blood into the heart

Question 7

Right a trio ventricular valve

Answer 7

Stop back flow of blood into atrium also known as tricuspid

Question 8

Chordae tendineae

Answer 8

Tendons heart strings stop valves from inverting under pressure

Question 9

Semi lunar valves

Answer 9

Found between arteries and ventricles prevent back flow into ventricles

Question 10

Left atrioventricular

Answer 10

Bicuspid or mitral valve

Question 11

Order of blood flow

Answer 11

Vein atrium ventricle artery

Question 12

First stage of cardiac cycle

Answer 12

Heart is relaxed diastole blood at low pressure in veins flow into atria the pressure increases in the aria as they fill this blood pushes against atrioventricular valves causing them to open and blood flows into ventricles below

Question 13

2nd stage cardiac cycle

Answer 13

When the atria are full atria systole blood is pushed through the atrioventricular valves into into ventricles pressure in the atria is increased due to contractions and pressure is increasing in ventricles as they fill with blood

Question 14

3rd stage of cardiac cycle

Answer 14

When the atria contract blood cannot flow into the vein beacause pressure of the bloood pushes on pocket valves in veins to shut them

Question 15

4 stage of cardiac cycle

Answer 15

After short delay the ventricles contract from the base upwards pressure inside the ventricles increases. The atria relaxes

Question 16

5th stage of cardiac cycle

Answer 16

Ventricular pressure reaches higher level than that in atria blood pushing against atrioventricular valves shut them giving the first heart sound Lub preventing back flow

Question 17

Stage 6 in cardiac cycle

Answer 17

Semilunar valves open under pressure and blood leaves heart through arteries

Question 18

7 stage of cardiac cycle

Answer 18

Ventricles relax pressure in aorta pulmonary artery exeedsbthat of the ventricles and blood pushes on semilunar valves which snap shut the second heart sound dub preventing back flow into heart

Question 19

How do we measure how efficient heart is

Answer 19

Cardiac output=HRxstroke volume

Question 20

How is the heartbeat controlled

Answer 20

Cardiac muscle cells are surrounded by capillaries and up to 35% of content is mitochondria
Heart beat is myotonic

Question 21

How is heart beat controlled

Answer 21

Pacemaker cells from intrinsic cardiac conduction system cause contractile cells in atria then ventricles to contract as impulses spread out through this system
Made of pacemaker cells send depolarising auothythmic produce action potentials like nerve cells without the need for an external stimuli
Leaky ion channels allow sodium ions to trickle in at a constant steady rate so eventually threshold is reached and the cell depolarises

Question 22

SA node

Answer 22

Is crescent shaped collection of myocytes found between upper wall of right atrium. And opening of vena cava is the primary pacemaker

Question 23

AV node

Answer 23

Secondary pacemaker

Question 24

Bundle fibres

Answer 24

Tertiary pacemaker

Question 25

Spread of nerve impulses

Answer 25

San avio bundle of his purkinji fibres