Chapter 15Cardiovascular System

Cardiovascular System

• heart• blood vessels

Average Size of Heart• 14 cm long• 9 cm wide•Fist-sized

Know all of this!

Heart Chambers

Right Atrium• receives blood from

• inferior vena cava• superior vena cava• coronary sinus

Left Atrium• receives blood from pulmonary veins

Right Ventricle• receives blood from right atrium

Left Ventricle• receives blood from left atrium

Heart Valves

Tricuspid Valve• right A-V valve• between right atrium and right ventricle

Bicuspid Valve• left A-V valve• aka mitral valve• between left atrium and left ventricle

Pulmonary Valve• semilunar valve• between right ventricle and pulmonary trunk

Aortic Valve• semilunar valve• between left ventricle and aorta

Path of Blood Through the Heart

Blood and its flow

• Remember that deoxygenated blood is represented by blue (but it is actually a deep, deep red)

• Oxygenated blood is represented by red and would be bright red in real life

• The deoxygenated blood always comes back to the heart and enters the right side (but from our view it looks like the left)

• It leaves and goes to the lungs to get oxygenated• It then enters the left side of the heart before getting

pumped out the aorta to the rest of the body

Path of BloodThrough the Heart

Pulmonary Circuit (lungs)CO2 blood from the

body

CO2 blood from the body

CO2 to the lungs

Superior vena cava

O2

CO2

Systemic Circuit (body)

O2 blood from the lungs

O2 blood from the lungs

O2 blood to the body

CO2

O2

Summary

•Atria receive blood

•Ventricles pump blood out of the heart

•Arteries carry oxygenated blood away from the heart

•Exception: pulmonary arteries carry deoxy. from the heart to the lungs

•Veins carry deoxygenated blood back to the heart

•Exception: pulmonary veins carry oxygenated blood from the lungs to the heart

Review of blood flow

• Deoxygenated blood comes in the SVC or IVC to the Rt. Atrium

• Through the tricuspid valve

• To the Rt. Ventricle

• Out the pulmonary valve

• Into the pulmonary artery

• To the lungs to get oxygenated

• Oxygenated blood comes back to the heart in the pulmonary veins into the Lt. Atrium

• Through the bicuspid valve

• To the Lt. Ventricle

• Out the aortic valve

• Into the Aorta and out to the rest of the body

The explanation of blood flow on the worksheet is great except that it leaves out the valves that are getting passed through, make sure you know that too!

“Pumps your Blood”

Coronary Arteries

• These are the arteries that feed the heart muscle with oxygen

• If these get clogged you have a heart attack• When oxygenated blood gets pushed into the aorta

there are detours leading to the coronary arteries• Coronary arteries right and left cardiac veins

coronary sinus right atrium

Summary of Changes During Cardiac Cycle

Lubb dupp

• This is the terminology most scientists use to describe the sound of the heart

• It is made by the opening and closing of valves• The lubb sound is made by the A-V valves closing• The dupp sound is made by the aortic and

pulmonary valves (semilunar) closing• Listen to your partners (or your) heart for this

sound with the stethoscope

The conduction of the heart

• Remember how your heart can even beat outside of your body???

• It has its own electrical system!!

The conduction of the heart

• The Sinoatrial (SA) node is at the top of the rt. atrium

• The Atrioventricular (AV) node is at the bottom of the rt. atrium (in between atrium and ventricle)

• The impulse is conducted down the septum of the ventricles

• It then branches back up

S-A node

A-V node

Follow the path!

Electrocardiogram

• recording of electrical changes that occur in the myocardium• used to assess heart’s ability to conduct impulses

P wave – atrial depolarization; about to contractQRS wave – ventricular depolarization; about to contractT wave – ventricular repolarization

Regulation of Cardiac Cycle

• physical exercise• body temperature• concentration of various ions

• potassium• calcium

• parasympathetic impulses decrease heart action• sympathetic impulses increase heart action• cardiac center regulates autonomic impulses to the heart

Regulation of Cardiac Cycle

Autonomic nerve impulses alter the activities of the S-A and A-V nodes

Blood Vessels

• arteries• carry blood away from ventricles of heart

• arterioles• receive blood from arteries• carry blood to capillaries

• capillaries• sites of exchange of substances between blood and body cells

• venules• receive blood from capillaries

• veins• carry blood toward RA of heart

*Veins have valves because they have to work against gravity. With each pump of the heart the blood goes through a valve and can’t go back!

Capillary Network

Regulation of Capillary Blood Flow

Precapillary sphincters • may close a capillary• respond to needs of the cells• low oxygen and nutrients cause sphincter to relax

Arterial Blood Pressure

Blood Pressure – force the blood exerts against the inner walls of the blood vessels

Arterial Blood Pressure• rises when ventricles contract• falls when ventricles relax• systolic pressure – maximum pressure• diastolic pressure – minimum pressure

Blood Pressure

• Desired to be under 120/80• Measured in mmHg• Top number is systolic (pressure when heart contracts)• Bottom number is diastolic (pressure when heart is at rest)• Both are important but especially the bottom number

because your heart needs to rest• Learn and practice taking blood pressure with a

sphygmomanometer