Human Heart and Blood Vessels

Intro to the circulatory system

Blood Vessels: The Vascular System

• Purpose: Taking blood to the tissues and back

• Include– Arteries– Arterioles– Capillaries– Venules– Veins

Figure 11.8a

The Vascular System

Figure 11.8b

Artery

Vein

Veins– Carry blood to the

heart from the body– Most veins have

oxygen poor (deoxygenated) blood

– Have valves to prevent the backflow of blood

– Veins branch off to venules

Pulmonary Vein

Major Veins• Jugular veins drain

the head/brain• Superior and inferior

venae cavae are the largest veins that drain into the heart

• The ONLY vein that carries oxygenated blood is the Pulmonary Vein

WHY?

Figure 11.12

Arteries

– Carry blood away from the heart to the body

– Most carry oxygenated blood to body cells

– They have thick muscular walls and you can feel a pulse in them

– Arteries branch off to form Arterioles

Major Arteries• Aorta is the largest

artery in the body.• Coronary arteries

supply blood to the heart itself

• Femoral artery supplies blood to the legs

• The ONLY artery that has deoxygenated blood is the pulmonary artery

Why??

Figure 11.11

How are the blood vessels all connected?

ARTERYVEIN

CAPILLARIES

arteriole

endothelium

connective tissue

smooth muscle

venule

valve

From Heart To heart

Capillaries– The walls are thin (one cell thick) so diffusion

of gases, nutrients, & wastes can take place– Red blood cells travel through one cell at a

time, single file

From the heart

Towards the heart

Why do capillaries need to be one cell thick?• So that diffusion can take place.

Capillary Bed – exchange vesselsInteraction of molecules flowing in and out of blood at a capillary bed.

• Oxygen and nutrients cross to body cells• Carbon dioxide and metabolic waste products cross into blood

Gas/nutrient exchange happens at the site of the capillary

GA

S E

XC

HA

NG

ES

O2

CO2

Glucose

What Influences Capillary Exchange?

There are 3 processes: 1.Blood pressure – created by the heart pumping

blood. It’s the pressure of blood against the walls of vessels

2.Diffusion – movement of substances from an area of GREATER concentration to an area of LESSER concentration

3.Osmotic Pressure – A force caused by the difference in solute concentration on either side of a membrane

Diffusion at Capillary Beds

Figure 11.20

Example: Movement of CO2 from areas of higher concentration (body cells) to areas of lower concentration (interstitial fluid and then even lower in the blood)

The lymphatic system • an extension of the circulatory system consisting of a fluid known

as lymph (a watery fluid derived from plasma that has seeped out of the blood system capillaries and mingled with the cells).

• helps regulate blood volume and pressure

How do capillaries interact with the lymphatic system?

How do capillaries interact with the lymphatic system?

• Rather than returning to the heart through the blood veins, this lymph enters a series of one-way lymphatic vessels/ducts that return the fluid to the circulatory system.

http://www.cancerresearchuk.org/about-cancer/cancers-in-general/what-is-cancer/body/the-lymphatic-system

How do capillaries interact with the lymphatic system?

• The vessels/ducts pass through hundreds of tiny, capsule-like bodies called lymph nodes. Located in the neck, armpits, and groin, the lymph nodes contain cells that filter the lymph and phagocytize foreign particles.

http://www.cancerresearchuk.org/about-cancer/cancers-in-general/what-is-cancer/body/the-lymphatic-system

Blood Vessel Disorders: What are Varicose Veins?

• Varicose veins are abnormal and irregular dilations in superficial (near the surface) veins.

• Varicose veins in the rectum are hemorrhoids

Blood Vessel Disorders: What is Phlebitis?

Phlebitis - the inflammation of a vein. Sometimes this inflammation causes a thromboembolism (clot) to form on the wall of the vein.Sometimes the clot breaks off (embolus) and travels through the body.

Do Now: 1.What is the function of an artery? What type of blood flows in arteries?

2.What is the function of a vein? What type of blood flows in veins?

3.What is the function of a capillary? What occurs here? How?

The Human HeartMuscular organ that contracts rhythmically and pumps blood through blood vessels

What are the functions of the heart?

1.Keeps O2-poor blood separate from O2-rich blood2.Keeps blood flowing in one direction3.Creates blood pressure to move blood through the body

Why is the mammalian circulatory system called a double pump system?

One half of the heart pumps blood to the lungs and then the other half pumps blood to the rest of the body.

Pulmonary Circuit-To and from the lungs-Oxygenates blood-Drops off CO2

Systemic Circuit-To and from rest of body-Drops off oxygen & nutrients-Picks up nutrients, wastes, & CO2

The LEFT side of the heart drives the Systemic Circuit. It pumps blood to the entire body (except lungs)

•To deliver oxygen and nutrients to body cells•To pick up waste (CO2)

from body cells•This is called “nutrient-for-waste” exchange

The RIGHT side of the heart drives the Pulmonary Circuit. It pumps blood to the alveoli in lungs for gas diffusion

•To release CO2 •To oxygenate the blood

Pulmonary Circulation System

Red portion of heart and red blood vessels carry oxygen-rich blood.

Blue portion of heart and blue blood vessels carry oxygen-poor blood.

Pump Your Blood Song

The heart is surrounded by a double-layered, sac-like structure called the pericardium. The space between the layers normally contains a very small amount of fluid.

DISORDER:

Pericarditis - inflammation of the pericardium

Coverings of the Heart

The wall of the heart is composed of 3 distinct layers.

The inner endocardium is smooth and is made up of connective tissue and epithelium, and is continuous with the endothelium of major vessels joining the heart.

The endocardium contains the Purkinje fibers.

The middle layer called myocardium consists of cardiac muscle and is the thickest layer of the heart wall.

The outermost layer, the epicardium, is made up of connective tissue and epithelium, and houses blood and lymph capillaries along with coronary arteries. It is the same as the visceral pericardium.

Chambers of the HeartThe heart has 4 internal chambers: • 2 Atria on top • 2 Ventricles below.Atria receive blood returning to the heart

and have thin walls Ventricles are thick walled and pump

blood out of the heart the body.

A septum divides the atria from each other and ventricles from each other.

Atria of the HeartThe Right Atrium receives blood

from the body• The Superior Vena Cava brings

blood from the upper parts of the body

• The Inferior Vena Cava brings blood from the lower parts of the body

The Left Atrium receives blood from the lungs by way of the pulmonary veins Septum

Ventricles of the HeartVentricles are thick walled and

pump blood out of the heart to the body.

The right ventricle pumps blood via the pulmonary artery to the lungs to be oxygenated

The left ventricle pumps blood out to the whole body via the aorta

DO NOW

List the structures of the heart that have deoxygenated blood.

List the structures of the heart that have oxygenated blood.

Label the Heart

Valves Prevent the Back Flow of Blood

Atrioventricular (A-V) valve ensures one way flow of blood from the atrium to the ventricles

• The right A-V valve is called the tricuspid

• The left A-V valve is called the bicuspid or mitral valve

Valves Prevent the Back Flow of Blood

Semilunar valves are found where the blood exits the heart. They are called “semilunar” because they resemble half moons

• Right side has a pulmonary semilunar valve

• The Left side has an aortic semilunar valve

Do Now:

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conducting_system_of_the_heart.html

What makes the heart beat?The conduction system of the heart is a route of specialized cardiac muscle fibers that initiate and stimulate contraction of the atria and the ventricles

Nodal tissue – the heart is controlled by nodal tissue

1.Sinoatrial node (S-A node or pacemaker), located on the posterior right atrium, generates the impulses for the heartbeat.

2.Atrioventricular node (A-V node) located in the septum.

Branches of the A-V bundle give rise to Purkinje fibers leading to papillary muscles; these fibers stimulate contraction of the papillary muscles at the same time the ventricles contract.

1. SA node sends out a stimulus, which causes the atria to contract

2. When this stimulus reaches the AV node, it signals the ventricles to contract

3. Impulses pass down the two branches of the atrioventricular bundle to the Purkinje fibers

4. After the stimulus reaches the Purkinje fibers the ventricles contract Purkinje Fibers

An electrocardiogram (EKG or ECG) is a test that checks for problems with the electrical activity of your heart.

http://allnurses.com/general-nursing-student/ekg-its-alphabetical-952130.html

https://my.clevelandclinic.org/services/heart/diagnostics-testing/electrocardiograph-tests/electrocardiogram-ekg

Ways to determine how well the heart is functioning

The sounds of the heart are caused by the closing of the

valves. 

A normal heartbeat produces the familiar “LUB-DUP” sound as the chambers contract and the valves close.

The  “lub” sound- quieter, longer, lower pitched- caused by the bicuspid and tricuspid valves (A-V valves) closing. The “dub” or “dup” sound- louder, shorter, higher pitched- caused by the semilunar valves closing. 

Ways to determine how well the heart is functioning

What is a Heart Murmur?

Heart murmurs are the clicking or the swishing sound after the “LUB”. The valve doesn't close properly and “leaks”

Listen to heart sounds

What is a mitral valve prolapse?• 1 in 20 americans

have this

• The defective heart valve leaflet can cause blood to flow back into the atrium

Mitral Valve Prolapse

• What are mitral valve prolapse symptoms?– Feeling like your heart is racing or is skipping beats – Heart palpitations – Chest pain that comes now and then – Shortness of breath – Dizziness – Anxiety

• Diagnosis?• When listening to your heart with a stethoscope, your

doctor may hear a clicking sound. The defective heart valve leaflet can make a pronounced "click" as it opens and closes. If blood is flowing back into the atrium, your doctor will hear a "whooshing" sound. This sound is called a heart murmur and is caused by the mitral valve prolapse.

Disorders of the heart

• Arrhythmia – Irregular heart beat– Bradycardia =<60bpm– Tachycardia =>100bpm

• Fibrillation – fast but uncoordinated contractions

Coronary Disorders• Atherosclerosis or

Arteriosclerosis - slow and progressive building up of plaque, fatty substances, cholesterol, cellular waste products, calcium and fibrin in the inner lining of an artery.

• This building up of plaque may lead to thickening and hardening of the arteries, subsequently blocking the blood flow either partially or totally in an artery.

Medmovie of atherosclerosis

Angina• Angina is chest pain or

discomfort that occurs if an area of your heart muscle doesn't get enough oxygen-rich blood.

• This pain is due to plaque in arteries

• Angina may feel like pressure or squeezing in your chest. The pain also can occur in your shoulders, arms, neck, jaw, or back. Angina pain may even feel like indigestion.

Thromboembolism• Thromboembolism is when a blood clot

breaks away from its place of origin and is carries to a new location. Thromboembolism leads to a heart attack when the embolus (traveling clot) blocks a coronary artery and a portion of the heart dies due to a lack of oxygen.

• A heart attack is called a myocardial infarction

AngioplastyAngioplasty is the technique of

mechanically widening a narrowed or obstructed blood vessel, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated. The balloon crushes the fatty deposits, opening up the blood vessel for improved flow, and the balloon is then deflated and withdrawn.

Coronary Bypass Surgery• Coronary Bypass

surgery is when a surgeon grafts segments of another vessel between the aorta and the coronary vessels, bypassing the areas that have a blockage

PulseYour pulse is your heart rate, or

the number of times your heart beats in one minute. Pulse rates vary from person to person. Your pulse is lower when you are at rest and increases when you exercise (more oxygen-rich blood is needed by the body when you exercise). Monitored at “pressure points” where pulse is easily palpated

• A normal resting pulse is 60-100 beats per minute

Figure 11.16

The Heart:Regulation of Heart Rate• Increased heart rate is regulated by:

– Sympathetic nervous system• Crisis• Low blood pressure

– Hormones• Epinephrine• Thyroxine

– Exercise can increase heart rate– Decreased blood volume

• Decreased heart rate is regulated by– Parasympathetic nervous system– High blood pressure or blood volume– Decreased venous return

Blood Pressure

• Measurements by health professionals are made on the pressure in large arteries

– Systolic – pressure at the peak of ventricular contraction

– Diastolic – pressure when ventricles relax

• Pressure in blood vessels decreases as the distance away from the heart increases

Measuring Arterial Blood Pressure

Figure 11.18

Variations in Blood Pressure• Human normal range is variable

– Normal• 140–110 mm Hg systolic• 80–75 mm Hg diastolic

– Hypotension• Low systolic (below 110 mm Hg)• Often associated with illness

– Hypertension• High systolic (above 140 mm Hg)• Can be dangerous if it is chronic

Figure 11.17

Comparison of Blood Pressures in Different Vessels

Blood Pressure: Effects of Factors• Temperature

– Heat has a vasodilation effect so pressure decreases– Cold has a vasoconstricting effect so pressure

increases

• Chemicals– Various substances can cause increases or decreases

• Diet• Neural factors

– Autonomic nervous system adjustments (sympathetic division)

• Renal factors– Regulation by altering blood volume– Renin – hormonal control

Animation: The Cardiac Cycle (Quiz 1)

Major blood supply to the body1. Brain2. Thyroid gland3. Thyroid artery4. Pulmonary circulation5. Pulmonary vein6. Aorta7. Splenic artery8. Spleen9. Superior mesenteric artery10. Renal artery11. Kidney12. Intestine13. Renal vein14. Portal vein15. Liver16. Inferior vena cava17. Hepatic veins18. Pulmonary artery19. Superior vena cava20. Thyroid vein

Capillary Beds

Figure 11.10