Cardiovascular System:

Heart and Blood Vessels

What to Know

• What are the functions of the cardiovascular system?

• What is the anatomy of the heart and blood vessels (veins and arteries)?

• How does blood flow through the heart?

• How is the heart beat regulated?

• What is blood pressure?

• What are common cardiovascular diseases and how might you prevent them?

The Circulatory System

• The cardiovascular system

consists of the blood vessels and

the heart

• The blood vessels conduct blood

in continuous loops

• The heart is a muscular pump

What is the cardiovascular system?

• Includes the heart and blood vessels

• Brings nutrients to cells and helps get rid of wastes

• Blood is refreshed in the lung, kidneys, intestine and liver

• Lymphatic vessels help this system by collecting excess fluid surrounding tissues and return it to the cardiovascular system

What are the functions of the

cardiovascular system?

1. Generate blood pressure

2. Transport blood

3. Exchange of nutrients and

wastes at the capillaries

4. Regulate blood flow as needed

What is the main pathway of blood in

the body?

Arteries

Arterioles

Capillaries

Venules

Veins

Figure 12.1 (1 of 2)

Veins: Carry blood back to the heart

Jugular veins

• Carry blood from headto the heart

Renal vein

• Carries blood from thekidney to the heart

Pulmonary veins

• Carry oxygenated blood

from the lungs to theheart

Inferior vena cava

• Carries blood from the

lower body back to theheart

Superior vena cava

• Carries blood from the

upper body back to the

heart

Iliac vein

• Carries blood from the

pelvic organs and

abdominal wallback to the heart

Radial vein

• Carries blood from the

hand back to the heart

Femoral vein

• Carries blood from the

thigh and inner kneeback to the heart

Figure 12.1 (2 of 2)

Arteries: Carry blood away from heart

Carotid arteries

• Deliver blood to the headand the brain

Aorta

• Delivers blood to the

body tissues

Pulmonary arteries

• Deliver oxygen-poorblood to the lungs

Coronary arteries

• Deliver blood to theheart muscle cells

Renal artery

• Delivers blood to thekidney

Iliac artery

• Delivers blood to

pelvic organs andabdominal wall

Radial artery

• Delivers blood tothe hand

Femoral artery

• Delivers blood tothigh and inner knee

Arteries• Carry blood away from the heart

• Their walls have 3 layers:

– Thin inner epithelium-tunica intima

– Thick smooth muscle layer-tunica media

– Outer connective tissue- tunica adventitia

• The elasticity of the arteries maintains pressure on the

blood between heartbeats to keep it flowing through the

vessels

• As the heart pumps blood into the arteries, they expand

such that one is able to feel a pulse

• The pulse rate is the same as the heart rate

Arterioles• are small arteries that regulate blood

pressure

• serve as gatekeepers to the capillary

networks keeping them open or closed

Capillaries

Capillaries• Microscopic vessels between arterioles

and venules

• Made of one layer of epithelial tissueallow for the exchange of materials between the blood and tissues

• Combined large surface area– Blood flows more slowly due to the large surface area

– Provides more time for the exchange of materials

The Blood Vessels Conduct Blood

in Continuous Loops

Figure 12.3b

Capillary Exchange

• At arterial end bp (30) is higher than (21)

osmotic pressure which is created by salts and

proteins so H20 leaves the bloodstream

• At midsection O2 and CO2 follow their

concentration gradients- O, a.a., glucose-out

CO2 and wastes in

• At venous end osmotic pressure is higher than

bp so H2O enters blood

Exchange at the capillary beds is primarily

a result of osmotic and blood pressure

Veins and venules:

• Venules are small veins that receive blood from

the capillaries

• Venule and vein walls have 3 layers:

– Thin inner epithelium

– Thin smooth muscle layer

– Outer connective tissue

• Veins carry blood toward the heart

• Veins that carry blood against gravity have

valves to keep blood flowing toward the heart

Thinner than arteries, can

expand more 70% of blood is

in the veins

Valves in

Veins

Figure 12.6a

Figure 12.6b

Valve

closed

Valve

open

Relaxed calf

muscles

Skeletal muscles

relax, and blood

fills the valves

and closes them.

Muscle contraction

squeezes the vein,

pushing blood

through the open

valve toward the

heart.

Valve

closed

Contracted calf

muscles

(b)

Know how you can tell the difference

between an artery and vein?

• The Human Heart

Anatomy of the Heart

• A large, muscular organ consisting of mostly cardiac tissue called the myocardium

• It is surrounded by a sac called the pericardium

• Consists of two sides, right and left, separated by a septum

• Consists of 4 chambers: 2 atria and 2 ventricles

• 2 sets of valves: semilunar valves and atrioventricular valves (AV valves)

• The valves give the resulting “lub” and “dub” sound of the heart Heart Sounds

Figure 12.7d

Right

ventricle

Superior vena

cava Aorta

Right

pulmonary

arteries

Pulmonary

semilunar valve

Right atrium

Right

pulmonary

veins

Right

atrioventricular

valve

(tricuspid valve)

Chordae tendineae

Inferior vena cava

Left pulmonary

arteries

Pulmonary trunk

Left pulmonary veins

Left atrium

Aortic semilunar valve

(hidden from view)

Left

atrioventricular

valve (mitral valve)

Left ventricle

Myocardium

Endocardium

Pericardium

Septum(d)

Right Ventricle

The Heart is a Muscular Pump

Figure 12.7a

What are the two cardiovascular pathways in the body?

• Pulmonary circuit: the

right side of the body that

brings blood from the

body to the heart and the

lungs

• Systemic circuit: the left

side of the heart that

brings blood to the entire

body to deliver nutrients

and rid it of wastes

How does blood flow through the

heart?• Inferior and superior vena cava (1) dump blood into the

right atrium (2)

• Right ventricle (3)

• 2 pulmonary arteries (4) that lead to the lungs (5) where blood becomes oxygenated

• Pulmonary veins (6) bring blood from the lungs back the left atrium (7)

• Left ventricle (8) is large and muscular to pump blood into the aorta (9) and to the rest of the body (10)

• Eventually blood will be pumped back to each vena cava(1)

Visualizing blood flow through the heart

Hyperlinks to Watch

• Animated tutorial of the Cardiac Cycle

• How the Heart Works

How do the structure of the vessels and heart

match their functions?

• The left ventricle is much more muscular than

the right ventricle because it must pump blood to

the entire body

• The arteries are more muscular than veins to

withstand the higher pressure exerted on them

• The veins have a thinner wall and a larger

center to store blood

How does the heartbeat occur?

• During systole the atria contract together followed by the ventricles contracting together

• This is followed by diastole, a rest phase, when the chambers relax

• This cardiac cycle, heartbeat, on average occurs 70 times/minute

What is the cardiac cycle?

How is the heartbeat controlled?

• Internal control:– The SA node in the right atrium initiates the heartbeat

and causes the atria to contract

– This impulse reaches the AV node, also in the right atrium, to send a signal down the AV bundle and Purkinje fibers that causes ventricular contraction

– These impulses travel between gap junctions at intercalated disks

• External control:– heartbeat is also controlled by a cardiac center in the

brain and hormones such as epinephrine and norepinephrine

Visualizing the heartbeat

Visualizing the gap junctions at the

intercalated disks

• An electrocardiogram

(ECG/EKG)

– Recording of the

electrical events

associated with the

heartbeat

– A powerful diagnostic

tool

• Abnormal patterns can

indicate heart problems

EKG

• A typical ECG/EKG

consists of three

distinguishable

deflection waves

– P wave

– QRS wave

– T wave

What is an electrocardiogram (ECG)?

• A record of the electrical changes in the heart muscle during a cardiac cycle

• The atria produce an electrical current when stimulated by the SA node called the P wave

• The contraction of the ventricles is the QRS complex

• The recovery of the ventricles is called the T wave

• Looking at these electrical changes allows doctors to detect abnormalities

How does a “normal” and abnormal

ECG compare?

Arrhythmia

What is blood pressure?• The pressure against a blood

vessel wall, usually measured in an artery in the arm

• The highest pressure is during blood ejection from the heart called the systolic pressure

• The lowest pressure is the diastolic pressure when the ventricles relax

• Average blood pressure is recorded at about 120/80 mmHg (systolic/diastolic)

• Reminder: this is controlled by the arterioles

• Pulse- rhythmic expansion

Korotkoff Sounds

Figure 12.14 (2 of 2)

How is blood pressure categorized?

What is important about blood

flow?

• Blood flow is under the

highest pressure in the

arteries but remember the

thick, muscular walls

• Blood flow is slower in the

capillaries which is

important to allow time for

exchange between cells

• Blood pressure is minimal

in the veins and venules

but blood flow increases

If blood pressure is so low in the veins why

does the blood flow increase?

• They have help:

1. Skeletal muscle

contraction

2. Breathing

3. Valves

The heart’s blood supply: Coronary circulation

• There are small

coronary arteries

that supply the heart

that are separate

from the systemic

and pulmonary

pathways of the

body

Figure 12.10a

Inferior

vena

cava

Superior

vena cava

Pulmonary

trunk

Aorta

Right

coronary

vein

Right

coronary

artery

Left coronary

artery

Left

coronary

vein

(a)

Pulmonary

veins

What is the hepatic portal system?

• A system that brings blood from the digestive tract rich in amino acids and glucose to the liver

• The liver synthesizes blood proteins and stores the glucose as glycogen

• The liver also plays a role in purifying blood from the digestive tract

• Finally, the blood will return to the heart via the inferior vena cava

Why should we care about cardiovascular

disease?

• Cardiovascular disease (CVD) is the most

common cause of death in the western

world

Disorders of the blood vessels:

• Hypertension/high blood pressure

• Atherosclerosis

• Stroke

• Heart attack

• Aneurysm

Hypertension

• High blood pressure results when blood moves through vessels at a rate higher than normal often due to arterial plaque

• 140/90 mmHg is considered hypertension

• A silent killer because there are few symptoms

• Can lead to a heart attack, stroke or kidney failure

Atherosclerosis

• A build up of plaque in blood vessels

• Plaque that is stationary is called a thrombus and an embolus when it detaches and can move to distant sites

• Associated with a stroke, heart attack and aneurysm

Stroke

• Also known as a cerebrovascular accident (CVA)

• Usually occurs when a cranial artery is blocked or bursts

• Part of the brain dies dues to lack of oxygen

• Symptoms may occur including numbness of hands or face, difficulty speaking and inability to see in one eye

Heart attack

• Also known as a myocardial infarction (MI)

• Part of the heart dies due to lack of

oxygen

• Can begin with angina pectoris, a pain that

radiates down the left arm due to a

blockage of a coronary artery

Aneurysm

• A ballooning of a blood vessel

• Atherosclerosis and hypertension can

weaken a vessel and cause ballooning

• The most commonly affected is the

abdominal artery or the arteries leading to

the brain

How are disorders of the blood vessels

treated?

• Dissolving blood clots: – t-PA is a drug that dissolves clots

• Treating clogged arteries:– Bypass surgery: usually a vein from the leg is taken

and used to bypass a clogged artery

– Stents: wire mesh cylinder inserted into a clogged artery to hold it open

– Angioplasty: a tube with a balloon is inserted into the clogged area and the balloon is then inflated to open the vessel

– A stent and angioplasty may be used in combination

Stents

Figure 12.17

Figure 12.18

Cardiovascular Disease

• Heart muscle dies because of an

insufficient blood supply during a heart

attack (myocardial infarction) and is

gradually replaced by scar tissue

• Scar tissue cannot contract, so part of the

heart permanently loses its pumping ability

Figure 12.19

Disorders of the heart and its treatment

• Disorders:

– Heart failure is when

the heart no longer

pumps properly

• Treatments:

– Left ventricular assist

device(LVAD)

– Heart transplant either

natural or artificial

Health Focus: The do’s and don’ts for

prevention of cardiovascular disease?

• Do not smoke

• Do not abuse drugs

• Keep your weight down to decrease chances of

hypertension and Type II diabetes

• Eat a healthy diet

– Low in saturated and trans fats

– Low in cholesterol

• Know your blood cholesterol

• Exercise