The Cardiovascular System

Mr. HunterAnatomy and Physiology

Anatomy and Physiology05/06/2013

• Objectives• SWBAT• Understand the function and the importance of the

Cardiovascular System• Analyze the structure of the heart• Examine circulation function and dynamics

• Bell Ringer: What is the function of a vasomotor mechanism?

The Cardiovascular System

• The system that supplies our body’s transportation needs is the cardiovascular system.

• Provides the replenishment of oxygen water and nutrients to cells

• Provides a means of removal of waste products from cells.

• Circulation of the blood is critical to maintaining homeostasis.

The Heart • The heart is located between the lungs in the lower portion of the mediastinum.

• 2/3 of the mass of the heart is located on the left of the thoracic cavity and 1/3 is located on the right.

• The heart is a triangular shaped organ, shaped and sized roughly like a closed fist.

• The apex which is the blunt pointed , lower edge of the heart lies on the diaphragm pointing toward the left.

• The apical heart beat is located between the 5th and 6th rib along the midline of the left clavicle.

The Heart

• The heart is positioned in the thoracic cavity between the sternum in front and the bodies of the thoracic vertebrae behind.

• Due to its location, the heart can be compressed or squeezed by the application of pressure to the lower body of the sternum using the heel of the hand.

• CPR allows the temporary maintaining of blood flow in the event of cardiac arrest.

The Heart

• The heart is a hollow organ. A partition divides it into right and left sides.

• The heart contains four cavities, or hollow chambers.

• The two upper chambers are called atria. The two lower chambers are called ventricles.

• The atria are smaller than the ventricles and their walls a less muscular. They are often called the receiving chambers.

• Blood exits from the ventricles into arteries – pulmonary and aorta. The ventricles are referred to as discharging chambers.

The Heart

• The wall of each heart chamber is composed of cardiac muscle tissue called myocardium.

• The septum between the atrial chambers is called the interatrial septum.

• The septum between the ventricles is called the interventricular septum.

• Each heart chamber is lined by a thin layer of smooth muscle endocardium.

• Inflammation of this layer is called endocarditis.

• The covering of the heart is called the pericardium. It consists of a parietal and visceral layer with lubricating fluid in between.

• The inner layer = visceral pericardium (epicardium) Fits like the skin of an apple.

• The outer layer = parietal pericardium. • Fits around the heart like a loose fitting sack.• Pericarditis = inflamed pericardium

Review 04/15/2013Anatomy and Physiology

Chapter 12

1. What is the name of the system that provides our body with its transportation needs?

2. Why is adequate circulation critical to the body?3. Where is the heart located?4. In which cavity and on which side is the greatest amount of mass from

the heart located?5. What portion of the heart lies on the diaphragm and points towards the

left?6. Where would a doctor or nurse place a stethoscope to listen to your

apical heart beat?7. What bony structures lie anterior and posterior to the heart?8. What are the names of the chambers of the heart?9. Describe myocardium, endocardium and pericardium.

Heart Action

• The heart serves as a muscular pumping device for distributing blood to all parts of the body.

• Pulmonary circulation and Systemic.• Contraction of the heart is called

systole.• Relaxation of the heart is called

diastole.• When the heart beats, the atria

contract first (atrial systole), forcing blood into the ventricles.

• Once filled, the two ventricles contract (ventricular systole) and force blood out of the heart.

Heart Valves

• The two valves that separate the atrial chambers above from the ventricular chambers below are called the atrioventricular valves (AV).

• The right AV valve is called the tricupsid valve. It consists of three leaf-like valve components.

• The left AV valve is called the bicupsid or mitral valve. It consists of two leaf-like valve components.

• Both AV valves prevent the backflow of blood into the atria when the ventricles contract.

• Stringlike structures called chordae tendineae attach the AV valves to the walls of the ventricles via papillary muscles extending from the floor of the ventrricles.

Heart Valves

• The semilunar valves (SL) valves are located between the two ventricular chambers and the arteries that carry blood away from the heart when systole occurs.

• The ventricles contract at the same time like the atria. The two SL valves open and close at the same time.

• The pulmonary SL valve is located at the beginning of the pulmonary artery and opens to allow blood to enter pulmonary circulation. The valve closes to prevents backflow of blood into the right ventricle.

• The aortic SL valve is located at the beginning of the aorta. The valve opens to allow blood to enter systemic circulation. It closes to prevent backflow of blood from the aorta into the ventricles.

Heart Sounds

• Two distinct sounds can be heard on the anterior chest wall.

• They are described as the lub dup sounds.

• The first lub sound is the result of the abrupt closure of the AV valves as the ventricles contract.

• The closure of the AV valves during ventricular systole prevents blood backflow into the atrial chambers.

• The second sound , dup is the closing of both the SL valves during ventricular diastole.

ReviewAnatomy and Physiology

04/16/20131. What are the two circulatory paths that the heart pumps blood to?2. What is the contraction of the heart called?3. What is the relaxation of the heart called?4. What is the name of the AV valve that separates the right atrium from

the right ventricle?5. What is the name of the valve that separates the left atrium from the left

ventricle?6. How many leaf like components does the right AV valve have in

comparison to the left AV valve?7. What are the names of the valves located between the ventricles and the

arteries that carry blood away from the heart?8. What function do chordae tendineae have?9. What are papillary muscles?10. If you only heard the lub sound on the anterior chest wall, what

structures may be defective within the heart?

Blood Flow Through The Heart

• The heart acts as two separate pumps.

• The right side of the heart pumps blood into the pulmonary system.

• The left side of the heart pumps blood into the systemic circulation.

• Blood enters the right atrium through two large veins called the vena cava. The superior and the Inferior vena cava provides the right atrium with blood.

• Venous blood lacks oxygen. Therefore, veins normally transport deoxygenated blood and arteries will transport oxygenated blood.

Blood Flow Through The Heart

• The blood leaving the right ventricle is deoxygenated. However it enters the pulmonary circulation via the pulmonary arteries.

• It is returned as oxygenated blood to the right atrium via four pulmonary veins.

• The blood returning to the left atrium crosses the mitral valve and enters the ventricle during atrial contraction.

• When the ventricles contract the left AV valve closes and the blood is pushed into the aortic SL valve – into systemic circulation.

Blood Flow Of The Heart

• The heart must perform a great amount of work by pumping through the pulmonary and systemic systems.•It requires a constant supply of oxygen and nutrients via the coronary circulation to perform this task.

Blood Flow Of The Heart

• Blood flows into the heart via the right and left coronary arteries. The location of the openings to these arteries are behind the aortic valve. The openings are called ostia

• When the aortic valve closes after ventricular systole, blood can flow in a retrograde manner into the coronary arteries.

• In both coronary thrombosis and coronary embolism, a blood clot blocks a certain region of artery and blood cannot supply that region of myocardial tissue with oxygen and nutrients. The cells will become injured and die resulting in a myocardial infarction (MI).

• Angina Pectoris is used to describe the chest pain resulting from a lack of oxygen to the myocardium.

ReviewAnatomy and Physiology

04/17/2013

1. How many separate pumps does the heart act as?2. Where does the right side of the heart pump blood into?3. Where does the left side of the heart pump blood into?4. What are the names of the two large veins which empty deoxygenated

blood from the superior and inferior portions of the body into the right atrium?

5. Explain why oxygenated blood is not found in the pulmonary arteries but it is found in the pulmonary veins.

6. What is the name of the circulation that provides oxygen and nutrients to myocardial tissue?

7. Where are the openings of the right and left coronary arteries found?8. What are these openings called?9. How and when does blood flow into the right and left coronary artery?

Cardiac Cycle

• The normal beating of the heart is regular and in a specific rhythm.

• Each complete heartbeat is called a cardiac cycle and includes systole and diastole (contraction and relaxation).

• Each cycle takes about 0.8 seconds to complete if the heart is beating at a rate of 72 beats per minute.

• Stoke Volume (SV) = the volume of blood ejected from the ventricles during each beat.

• Cardiac Output (CO) = the volume of blood pumped by one ventricle per minute. CO = HR x SV

• Normal CO = 5 L/min

Some Normal Values

• Stroke Volume (SV) = 60 – 130 ml• Heart rate (HR) = 60 – 100 bpm• Cardiac Output (CO) = 4 – 8 L/min• Systolic Pressure = 100 – 140 mmHg• Diastolic Pressure = 60 – 90 mmHg• Ejection Fraction (EF) = 50 – 70%* ( percentage of blood ejected from LV) *

Conduction System of the Heart

• Cardiac muscle cells have an intrinsic property of contracting on their own.

• The rate of contraction is controlled by the autonomic nervous system.

• The heart has its own conduction system for coordinating contractions during the cardiac cycle.

• Intercalated disks are connections that electrically join cardiac muscle fibers into a single unit that allows for impulse conduction through the entire wall of a heart chamber.

Conduction System of the Heart

• The structures that make of the conduction system of the heart are:

• Sinoartrial node or pacemaker.• Atrioventricular Node (AV node)• AV bundle, or bundle of His• Purkinje fibers• Impulse conduction starts in the SA

node.• It spreads in all directions through

the atria. This causes atrial fibers to contract.

• The pulse will then travel to the AV node and to the AV bundle / bundle of His and to the Purkinje fibers to cause ventricular contraction.

Conduction System of the Heart

• Normally, therefore a ventricular beat will follow an atrial beat.

• Myocardial infarctions, endocarditis and other heart disorders can cause the heart’s conduction system to malfunction.

• Heart block occurs when impulses cannot reach the ventricles. The ventricles will therefore contract at a much slower rate than normal.

• This condition may be treated by the implantation of an artificial pacemaker that will increase the rate of ventricular contractions to normal.

Conduction System of the Heart

• Small electrical currents are generated by the conduction system of the heart.

• These currents can travel through surrounding tissues to the surface of the body and be transformed into visible tracings by an electrocardiogram – EKG or ECG

• The EKG is a graphical record of the heart’s activity.

Electrocardiogram Waves

• The P wave –atrial depolarization (contraction)•QRS complex – Ventricular depolarization and atrial repolarization (relaxation)•T wave – Ventricular repolarization

Anatomy and Physiology Review 04/25/2013

1. What is the term for each complete heartbeat?2. How long does it take for a cardiac cycle to complete if the heart rate is

72 beats per minute?3. Define stroke volume and cardiac output.4. What is the formula for finding cardiac output?5. The rate of cardiac muscle tissue is controlled by what system within the

body?6. What are the functions of intercalated disks?7. List the structures that make up the conduction system of the heart.8. Outline the path of electrical impulses through the heart including what

chambers are involved.9. Name two cardiac abnormalities that can cause the conduction system to

malfunction.10. What is heartblock and how can it be treated?11. What is an EKG and describe three common waves or deflections.

Electrocardiogram

• P wave – Atrial depolarization, spreads from the RA to the LA.Normal value = 80ms• PR Segment – Impulse does not produce contraction, it is traveling toward ventricles. Normal = 50 to 120 ms.• PR Interval – The time it takes for the impulse to travel from the SA node to the AV node where it then enters the ventricles. The normal value is 120-200 ms.

Electrocardiogram• QRS Complex – Rapid depolarization of right and left ventricles. Normal Ranges = 80 to 120 ms. •Shorter QRS values are found in children and in rapid states of heart beat – tachycardia.•Prolonged values = hyperkalemia or bundle branch block.•J Point – Point at which QRS ends and ST segments begins.•ST segment = ventricles are depolarized. Normal = 80 to 120 ms above = MI•T wave = 160 ms ventricles relax.•U = IV septum repolarization

Electrocardiogram

• ST interval – Measured from J point to end of T wave. Normal = 320 ms. •Represents slow phase of ventricular repolarization.•QT interval – Measured from beginning of QRS to end of T. Normal = up to 420 ms in heart rates of 60 bpm. •Prolonged QT = vetricular tachyarthmias and sudden death.

Blood Vessels

• Arterial blood is pumped through a series of large distribution vessels- arteries.• The largest artery in the body is the aorta.•Arteries progressively become smaller as they move away from the heart becoming arterioles.• Arterioles control the flow of blood into microscopic exchange vessels called capillaries.

Blood Vessels

• Blood enters via capillary sphincter smooth muscle cells. Within the capillary beds, the exchange of nutrients and gases occur between blood and the tissue fluid around the cells.• The blood is drained from the capillary bed and then enters vessels called venules which progressively become larger to form veins.• The two largest veins the SVC and the IVC return blood to the RA.

Structure of Vessels

• Arteries, veins and capillaries differ in structure.•Three layers are found in arteries and veins.•The outermost layer = tunica externa or adventitia. It is made of connective tissue fibers to reinforce the walls under pressure.• The tunica media is the smooth muscle middle layer. It is much thicker in arteries than in veins and contains a thin layer of elastic tissue. This layer is under control of the ANS and maintains BP and blood distribution.

Structure of Vessels

• The tunica intima lines the arteries and veins. It is a single layer of squamous epithelial cells called endothelium that lines the inner surface of the entire cardiovascular system.• The veins have one-way valves not present in arteries. These valves prevent backflow of blood.

Anatomy and PhysiologyReview 04/26/2013

1. Describe the P wave, the PR segment and the PR interval.2. Where would you expect to find shorter QRS values?3. What conditions would reflect prolonged QRS values?4. ST segment elevated values are an indication of what type of cardiac

event?5. What do U wave deflections indicate?6. What could be the cause of a prolonged QT interval?7. What is the name of the largest artery in the body?8. As arteries become smaller, what type of vessels do they become?9. When blood leaves the capillary bed, what vessel does it travel through?10. Name and describe the three structural layers of arteries and veins.11. What structure is found in veins but not found in arteries?

Hepatic Portal Circulation

• Hepatic portal circulation refers to the route of blood flow through the liver.

• Veins from the stomach, intestines, gallbladder and spleen do not pour blood directly into the Inferior Vena Cava (IVC) as do the veins from other abdominal organs.

• Blood is funneled to the liver by the hepatic portal vein.

• Blood passes through the liver before it reenters regular venous return to the heart.

• Blood exits the liver via hepatic veins which drain into the IVC.

Hepatic Portal Circulation

• The diverted blood in this circulatory path is sent through a second capillary bed in the liver.

• Liver cells can remove high concentrations of glucose and convert it to glycogen.

• Liver cells can also remove and detoxify various poisonous substances that may be in the blood.

• This system is another example of helping the body maintain homeostasis.

Fetal Circulation

• Circulation in the body before birth differs from circulation after birth because the fetus must obtain oxygen and nutrients only from maternal blood.

• Fetal blood must be carried to the placenta and returned to the body of the fetus.

• This is accomplished by three vessels that compose the umbilical cord.

• Two umbilical arteries• One umbilical vein• The umbilical artery carries oxygen

poor blood.• The umbilical vein carries oxygen

rich blood.

Fetal Circulation

• The ductus venosus is a continuation of the umbilical vein.

• It serves as a shunt allowing the blood to bypass the immature liver and empty directly into the IVC.

• The foramen ovale shunts blood from the RA to the LA, bypassing the immature lungs.

• The ductus arteriosus connects the aorta and the pulmonary artery. The blood will bypass the lungs through this route.

Anatomy and Physiology Review04/30/2013

1. What does hepatic portal circulation refer to?2. Veins from which organs do not pour directly into the IVC?3. What vein funnels blood into the liver?4. What are two functions that this system can provide for

blood traveling through its capillary bed?5. Name the three vessels that carry blood to the placenta and

return it to fetus.6. What is the function of the foramen ovale?

Bell Ringer 04/30/2013Label and Describe each wave of the EKG trace below

Blood Pressure

• The pressure or push of blood as it flows through the cardiovascular system.

• It is the highest in the arteries and the lowest in the veins.

• The blood pressure gradient is the difference between two blood pressures.

• The BP for systemic circulation is the difference of the mean BP in the aorta and the pressure at the termination of the vena cava.

Blood Pressure• The mean BP in the aorta is

100 mmHg and within the termination of the vena cava it is 0 mmHg.

• The systemic BP gradient is 100 - 0 = 100 mmHg.

• The BP gradient is responsible for keeping the blood flowing.

• When a BP gradient is not present, blood does not circulate.

Blood Pressure

• Hypertension HTN – high blood pressure can cause the rupture of one or more blood vessels.

• If BP is too low - hypotension, then vital organs will not be perfused. Circulation would soon cease.

• Massive hemorrhage can kill in this way.

Factors that Influence Blood Pressure

• Blood Volume• Strength of Contraction• Heart Rate• Thickness of Blood

Blood Volume – The larger the volume of blood in the arteries, the greater the pressure that is exerted on their walls.

• The lower the volume, the lower the blood pressure.

Factors that Influence Blood Pressure

• Hemorrhage is a pronounced loss of blood, this decrease in volume causes a decrease in BP.

• Diuretics-drugs that promote water loss by increasing urine output.

• These drugs are often used to treat HTN by decreasing blood volume.

Factors that Influence Blood Pressure

• The volume of blood in the arteries is determined by how much blood is pumped into them by the heart.

• It is also determined by how much blood is being drained from them via the arterioles.

• The diameter of the arterioles plays an important role in determining how much blood is drained from the arteries.

• Heart Contractions – Strength and rate of the heartbeat affect CO and therefore BP.

• The stronger the contraction, the more blood is pumped into the arteries.

Anatomy and Physiology Review 05/01/2013

1. What can blood pressure be defined as?2. Where is blood pressure normally the highest and the lowest?3. What is a blood pressure gradient?4. How is the systemic blood pressure gradient determined?5. What is the blood pressure gradient responsible for?6. What is the difference between hypertension and hypotension?7. What affects can hypertension and hypotension have on the circulatory

system?8. Name three factors that can influence blood pressure.9. How does the volume of blood in the arteries increase or decrease blood

pressure?10. What type of drugs are commonly used to treat hypertension and how

do they work?

Factors that influence Blood Pressure

• A decrease in the heart’s output will decrease the volume of blood in the arteries. The decrease in arterial blood volume decreases blood pressure.

• A stronger heartbeat increases blood pressure, and a weaker beat decreases it.

• Heart Rate - The rate of the heartbeat also may affect arterial blood pressure.

• When the heart beats faster, more blood enters the aorta, and therefore the arterial blood pressure should increase if the SV does not decrease.

Factors that influence Blood Pressure

• When a change in heart rate produces a change in blood pressure there must also be a change in stroke volume.

• Blood viscosity - If blood becomes less viscous than normal, blood pressure will decrease.

• If a person suffers a hemorrhage, fluid moves into the blood from the interstitial fluid. This dilutes the blood and decreases blood pressure.

• Polycythemia is a condition in which the number of red blood cells increase to compensate for low oxygen levels. This can cause an increase in viscosity.

Factors That Influence Blood Pressure

• Peripheral Resistance describes any force that acts against the flow of blood in a blood vessel.

• Tension of muscles within the walls of blood vessels can affect PR.

• When blood vessel walls are relaxed resistance is low.

• When blood vessel muscles are contracted resistance is high.

• Vasomotor mechanism- adjustment of muscle tension in vessel walls to control blood pressure and blood flow.

• CVP – Central Venous Pressure should be 0 mmHg. If not, blood flow into RA is slowed.

Anatomy and Physiology Review05/06/2013

1. What affect does a strong heartbeat have on blood pressure?2. How does stroke volume affect heart rate and blood pressure?3. What is the relationship between blood viscosity and blood pressure?4. What is polycythemia?5. What can peripheral resistance be defined as?6. When blood vessel walls are contracted, what happens to PR?7. What is a vasomotor mechanism?8. What is normal CVP?9. If the CVP is above normal, what could the problem possibly be?

Factors of CVP

Pulse Pressure

• Pulse results from an artery expanding and then recoiling.

• To feel a pulse , you must place the fingertips over an artery that lies near the surface of the body and over a bone or other firm base.

• A pulse can provide information about the rate, strength and rhythm of a heartbeat.

Pulse Pressure

• Pulse results from an artery expanding and then recoiling.

• To feel a pulse , you must place the fingertips over an artery that lies near the surface of the body and over a bone or other firm base.

• A pulse can provide information about the rate, strength and rhythm of a heartbeat.

Pulse Pressure

• Three pulse points are located on each side of the head and neck:

1. superficial temporal artery in front of the ear

2. The common carotid artery in the neck along the edge of the sternocleidomastoid muscle

3. The facial artery at the lower margin of the mandible below the mouth

Pulse Pressure

• Pulse points are located at three points in the upper limb.

1. Axilla over the axillary artery

2. Brachial artery at the bend of the elbow

3. Radial artery at the wrist Most frequently

monitored pulse.

Pulse Pressure

• Pulse points are located on three locations in the lower extremities.

1. Femoral artery2. Popliteal artery – behind

and proximal to the knee3. Dorsalis pedis artery – on

the front surface of the foot just below the bend of the ankle joint.

Anatomy and PhysiologyReview 05/09/2013

1. Name three mechanisms that keep venous blood moving back through the CV circuit into the RA.

2. What causes a pulse?3. To feel a pulse, what must you do?4. What information can a pulse provide?5. Name three pulse points located on each side of the head

and neck.6. Name three pulse points of the upper limb.7. Name the three pulse points of the lower extremities.8. Where is the popliteal artery located?