2.5: the cardiac cycle

What are the 2 simultaneos pumped circuits

• the pulmonary (right side)

• the systemic/cardiac (left side)

What is atrial and ventricular muscle control

• concentration = systole

• relaxation = diastole

what are the sounds of heart beats

• “Lub” = 1st sound of the heart —- closure of the tri and bicuspid valves

• “Dub” = 2nd sound of the heart —- closure of the Pulmonary and Aortic valves 

What causes the contractions of the heart

The contraction are caused by nerve impulses from the sinoatrial node (atop the right atrium)

What can trigger this

Stretching of atrial wall triggers start of signal cascade which travels down to ventriculus (signal which tell the ventriculus to contract)

What controls the pace of the heart

The medulla oblongata and hormones

What does irregularities cause and what’s the solution

This causes sick sinus syndrome which can be resolved using a pacemaker

What is blood pressure

Blood pressure is a measure of the force exerted on arterial walls

How do you measure this

Systolic pressure over diastolic pressure

healthy: 120/80

systolic vs diastolic pressure

Systolic is the pressure on arterial walls while the heart beats and diastolic pressure is the pressure during the pauses

Hypertension vs Hypotension

• Hypertension : chronically high BP (Causes organ damage and aneurysm) 

• Hypotension: abnormally low BP (causes dizziness, weakness and fainting)

Difference between fish and human circulatory circuits

Fish have a single circulatory system where the blood only passes through the heart once

Humans have a double circulatory system where the blood passes through the heart twice

why is carbon monoxide dangerous

It binds to hemoglobin much more strongly (higher affinity for CO) and doesn’t let go

Greatly affects your bodies ability to distribute oxygen