Heart

Question 1

Cardiac Muscle

Answer 1

• Is what the heart is made from
  -Is myogenic- contracts without hormonal/nervous stimulation
  -Never fatigues, as long as it has supply of oxygen

Question 2

Coronary Arteries

Answer 2

-Supply the cardiac muscle with oxygen
-Branch of from aorta
-Blockage of these arteries result in myocardial infarction (heart attack) because the heart will be deprived from blood and oxygen therefore the muscle cells become unable to respire

Question 3

Flow of blood in the heart

Answer 3

-Vena cava carries deoxygenated blood from body into the hearts right atrium

-This pumps the blood through the
A.V(tricuspid) valve into the right ventricle

-The right ventricle pumps to semi lunar(pulmonary) valve into pulmonary artery which takes deoxygenated blood to lungs

-Blood becomes oxygenated and comes back through pulmonary vein into left atrium

-Next goes through A.V (bicuspid) valve into left ventricle into semi lunar (aortic) valve then into aorta which sends the oxygenated blood to the rest of the body

Question 4

Adaptations of chambers

Answer 4

Atria’s
-Thin muscular walls, as doesn’t need to contract as hard as is only pumping blood to ventricles
-Elastic walls to stretch when blood enters

Ventricles
-Thicker muscular walls to enable contraction
-This creates a higher blood pressure, to enable blood to flow for longer distances (lungs and rest of body)
- Right ventricle has thinner walls in comparison to the left ventricle. This is because the R.V pumping blood to lungs which means it needs to be at a lower pressure to prevent damaging capillaries in the lungs and so blood flows slowly to allow time for gas exchange
-Left ventricle has thicker muscular walls to enable larger contractions of the muscles to create higher pressure

Question 5

Valves

Answer 5

-Prevent backflow of blood
-Open when pressure is higher behind the valve
Close when pressure is higher in front of the valve

Question 6

Septum

Answer 6

-Separates the deoxygenated blood and oxygenated blood
-Maintains a high concentration gradient of oxygen in oxygenated blood to enable diffusion at respiring cells.

Question 7

The Cardiac Cycle

Answer 7

Diastole
-Atria’s and ventricle are relaxed
-Blood enters atria via vena cava/pulmonary vein
-This increases pressure in atria

Atrial systole
-The atria muscular walls contract, increasing the pressure, causing atrioventricular valves to open and blood to flow into ventricles
-The ventricles are relaxed (ventricular diastole)

Ventricular systole
-The ventricles contract, increasing the pressure beyond that of the atria’s
-The A.V. valve closes and semi lunar opens.
The blood is pushed out of ventricles into arteries (pulmonary artery/ aorta)

Question 8

Cardiac Output

Answer 8

Heart Rate X Stroke Volume