Physio Midterm 2 (Lectures 9 -

Function of the Cardiovascular System

**Distributes things within the body

• Transport: respiratory: gas exchange (O2 & CO2) → from lungs to cells, nutrition (digestive system → cells), waste (toxic waster → liver/kidney)

• Regulation: hormonal (endocrine → target cells), temperature (blood diversion), immune (transport leukocytes/white blood cells, cytokines)

Systemic Circuit

• carries O2 rich blood from heart to body, then returns to heart deoxygenated

• Higher pressure, blood must travel throughout body (120/80)

Pulmonary Circuit

• moves deoxygenated blood from heart to lungs, returning as oxygenated blood to the heart

• Lower pressure, blood DOES NOT have to travel as far (25/8)

Veins

Return to the heart

• blood not always deoxygenated, depends on circuit

Arteries

Move away from the heart

Reading Blood Pressure

Higher Number = when heart is CONTRACTING

Lower Number = when heart is RELAXING

Superior vena cava

blood drains into right ventricle

Aorta

blood from left ventricle to rest of the body

Diastole

• Relaxed phase of cardiac cycle

• Heart muscle expands → heart fills with blood

• Blood flows inside heart through AV Valves

Pulmonary artery

blood going from right ventricle to lungs

Coronary artery and veins

• deliver oxygen and nutrients to cardiac muscle cells

• deliver blood to heart muscle

What does the fat around the heart tell you?

• Cardiac myosites are oxidative, can burn fat as an energy source

• Cardiac muscles are AEROBIC

AV Valve

Atrial-ventricular valve

• valve between right atrium and right ventricle

• blood returning from lung (pulmonary veins) to left atrium

Semilunar Valves

• blood from right ventricle to pulmonary artery

• blood from left ventricle to aorta → rest of body

• MUST HAVE VENTRICULAR CONTRACTION FOR VALVES TO OPEN

Reducing volume _____ pressure

increases

Pressure (Syringe Model)

**overall idea: change in volume to increase pressure

• pressure follows a gradient

• moves from areas of high pressure (inside heart) to low pressure (blood vessel)

• one-way valves keep blood moving through blood vessel in one direction after contraction (systole) during relaxation (diastole)-

→ AV and Semilunar valves are one-way, prevent backflow

Systole

• Contracted phase of the cardiac cycle

• Heart muscle contracts → pumps blood

• Blood ejected out through Semilunar valves

Do both the pulmonary and systemic circuits get blood at the same time?

Yes, both receive blood at the same time

→ more blood to systemic circuit

Phase 1 of Cardiac Cycle

• Late diastole

• preparing to contract

• ventricles are completely open, blood flows freely into heart (blood flows into both atria and ventricles)

Phase 2 of Cardiac Cycle

• Atrial systole: muscular contraction

• Atria contract and push blood into ventricles

• Ventricle is full

Phase 3 of Cardiac Cycle

• Isovolumic ventricular contraction

• Ventricle prepares to contract

• Stiffening of ventricle

• AV valves slam shut

Phase 4 of Cardiac Cycle

• Ventricular systole

• Heart contracting from bottom → up

• Squeezes blood up and out

• Blood flows out of Semilunar valves into Aorta and Pulmonary Arteries

Phase 5 of Cardiac Cycle

• Isovolumic ventricular relaxation

• Ventricle relaxes

• Pressure drops

• Blood can be brought in again from atria

• Cycle repeats at phase 1

Right Ventricle

• receives deoxygenated blood

Left Ventricle

• receives oxygenated blood from lung