The Circulatory

System

By Mr. Danilo Villar Rogayan Jr.

Instructor I, Department of Natural Sciences

College of Agriculture & Veterinary Medicine

RMTU San Marcelino

27-2

Introduction

• The cardiovascular system consists of heart and blood vessels

• Sends blood to• Lungs for oxygen

• Digestive system for nutrients

• CV system also circulates waste products to certain organ systems for removal from the blood

27-3

The Heart: Structures

• Cone-shaped organ about the size of a loose fist

• In the mediastinum

• Extends from the level of the second rib to about the level of the sixth rib

• Slightly left of the midline

27-4

The Heart: Structures (cont.)

Heart is bordered:

Laterally by the lungs

Posteriorly by the vertebral

column

Anteriorly by the sternum

Rests on the diaphragm

inferiorly

27-5

The Heart: Structures (cont.)

• Heart coverings• Pericardium

• Covers the heart and large blood vessels attached to the heart

• Visceral pericardium

• Innermost layer

• Directly on the heart

• Parietal pericardium

• Layer on top of the visceral pericardium

• Heart walls:• Epicardium

• Outermost layer

• Fat to cushion heart

• Myocardium • Middle layer

• Primarily cardiac muscle

• Endocardium • Innermost layer

• Thin and smooth

• Stretches as the heart pumps

Click for Larger View

27-7

The Heart: Structures (cont.)

• Four chambers• Two atria

• Upper chambers

• Left and right

• Separated by interatrial septum

• Two ventricles• Lower chambers

• Left and right

• Separated by interventricular septum

Click for

View of

Heart

Atrioventricular septum separates the atria

from the ventricles

27-8

The Heart: Structures (cont.)

• Tricuspid valve – prevents blood from flowing back into the right atrium when the right ventricle contracts

• Bicuspid valve – prevents blood from flowing back into the left atrium when the left ventricle contracts

• Pulmonary valve – prevents blood from flowing back into the right ventricle

• Aortic valve – prevents blood from flowing back into the left ventricle Click for

View of

Heart

27-10

The Heart: Blood Flow

Deoxygenat

ed blood in

from bodyOxygenated

blood in lungs

Atria Contract Ventricles Contract

Deoxygenate

d blood out

to lungs

Oxygenated

blood out to

body

27-11

The Heart: Blood Flow (cont.)

Right

Atrium

Right

Ventricle

Pulmonary

Semilunar

Valve

Left

AtriumBicuspid

Valve

Left

Ventricle

Pulmonary

Valve

Tricuspid

Valve

Aortic

Semilunar

Valve

LungsBody

27-12

The Heart: Cardiac Cycle

• Right atrium contracts• Tricuspid valve opens

• Blood fills right ventricle

• Right ventricle contracts• Tricuspid valve closes

• Pulmonary semilunar valve opens

• Blood flows into pulmonary artery

• Left atrium contracts • Bicuspid valve opens

• Blood fills left ventricle

• Left ventricle contracts• Bicuspid valve closes

• Aortic semilunar valve opens

• Blood pushed into aorta

One heartbeat = one cardiac cycle

Atria contract and relax

Ventricles contract and relax

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The Heart: Cardiac Cycle (cont.)

• Influenced by• Exercise

• Parasympathetic nerves

• Sympathetic nerves

• Cardiac control center

• Body temperature

• Potassium ions

• Calcium ions

27-14

The Heart: Heart Sounds

• One cardiac cycle – two heart sounds (lubb and dubb) when valves in the heart snap shut• Lubb – First sound

• When the ventricles contract, the tricuspid and bicuspid valves snap shut

• Dubb – Second sound • When the atria contract and the pulmonary and aortic valves

snap shut

27-15

The Heart: Cardiac Conduction System

• Group of structures that send electrical impulses through the heart

• Sinoatrial node (SA node)• Wall of right atrium

• Generates impulse

• Natural pacemaker

• Sends impulse to AV node

• Atrioventricular node (AVnode)• Between atria just above ventricles

• Atria contract

• Sends impulse to the bundle of His

• Bundle of His

• Between ventricles

• Two branches

• Sends impulse to Purkinje fibers

• Purkinje fibers

• Lateral walls of ventricles

• Ventricles contract Link to

Diagra

m

27-17

Blood Vessels: Arteries and Arterioles

• Strongest of the blood vessels

• Carry blood away from the heart

• Under high pressure• Vasoconstriction

• Vasodilation

• Arterioles• Small branches of

arteries

• Aorta• Takes blood from the

heart to the body

• Coronary arteries• Supply blood to heart

muscle

27-18

Blood Vessels: Veins and Venules

• Blood under no pressure in veins

• Does not move very easily

• Skeletal muscle contractions help move blood

• Sympathetic nervous system also influences pressure

• Valves prevent backflow

• Venules

• Small vessels formed when capillaries merge

• Superior and inferior vena cava

• Largest veins

• Carry blood into right atrium

27-19

Blood Vessels: Capillaries

• Branches of arterioles

• Smallest type of blood vessel

• Connect arterioles to venules

• Only about one cell layer thick

• Oxygen and nutrients can pass out of a capillary into a body cell

• Carbon dioxide and other waste products pass out of a body cell into a capillary

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Checkpoint!!!

How do arteries control blood pressure?

ANSWER: The muscular walls of arteries can

constrict to increase blood pressure or dilate to

decrease blood pressure.

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Blood Pressure

• Force blood exerts on the inner walls of blood vessels• Highest in arteries

• Lowest in veins

• Systolic pressure • Ventricles contract

• Blood pressure is at its greatest in the arteries

• Diastolic pressure • Ventricles relax

• Blood pressure in arteries is at its lowest

• Reported as the systolic number over the diastolic number

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Blood Pressure (cont.)

• Control is based mainly on the amount of blood pumped out of the heart

• The amount of blood entering should equal the amount pumped from the heart

• Starling's law of the heart• Blood entering the left ventricle stretches the wall of the

ventricle

• The more the wall is stretched

• The harder it will contract and

• tTe more blood it will pump out

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Blood Pressure (cont.)

• Baroreceptors• Also help regulate blood pressure

• Located in the aorta and carotid arteries

• High blood pressure in aorta message to cardiac center in brain decreases heart rate lowers blood pressure

• Low blood pressure in aorta message to cardiac center in the brain increases heart rate increases blood pressure

27-24

Checkpoint!!!

What is the difference between the systolic

pressure and diastolic pressure?

ANSWER: Systolic pressure is the result of the

contraction of the ventricles increasing the

pressure in the arteries. Diastolic pressure is the

result of the relaxation of the ventricles lowering

the pressure in the arteries.

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Circulation

• Pulmonary circuit right atrium right ventricle pulmonary artery trunk pulmonary arteries lungs pulmonary veins heart (left atrium)

• Systemic circuitleft atrium left ventricle aorta arteries

arterioles capillaries venules veins vena cava heart (right atrium)

27-26

Circulation (cont.)

• Arterial system• Carry oxygen-rich blood

away from the heart

• Pulmonary arteries carry oxygen-poor blood

• Paired – left and right artery of the same name

27-27

Circulation (cont.)

• Venous system• Carries oxygen-poor

blood toward the heart• Except pulmonary veins

• Most large veins have the same names as the arteries they are next to

Hepatic portal system

Collection of veins

carrying blood to the

liver

Click for Larger View

27-29

Checkpoint!!!

ARTERIES: Pulmonary arteries carry oxygen-poor blood.

Do pulmonary arteries carry blood with high levels of

oxygen or low levels of oxygen?

27-30

Blood

• A type of connective tissue• Red blood cells

(erythrocytes)

• White blood cells (leukocytes)

• Platelets – cell fragments

• Plasma – fluid part of blood

Average-sized adult has

4 to 6 liters of blood

Amount depends on:

Size of person

Amount of adipose tissue

Concentrations of ions

Females have less than

males

27-31

Blood Components

• Hematocrit • The percentage of red blood cells

• Normal is about 45%

• White cells and platelets = 1%

• Plasma = 55%

27-32

Blood Components: Red Blood Cells

• Erythrocytes

• Transport oxygen throughout the body

• Small biconcave-shaped cells

• Hemoglobin is a pigment in RBCs• Oxyhemoglobin carries oxygen; bright red

• Deoxyhemoglobin does not carry oxygen; darker red • Carries carbon dioxide, so also called carboxyhemoglobin

• Anemia – low RBC count

• Erythropoietin – regulates production of RBCs

27-33

Blood Components: Red Blood Cells (cont.)

27-34

Blood Components: White Blood Cells

• Granulocytes• Neutrophils (55%) –destroy bacteria, viruses, and

toxins in the bloodstream (phagocytes)

• Eosinophils (3%) – get rid of parasitic infections such as worm infections

• Basophils (1%) – control inflammation and allergic reactions

• Agranulocytes• Monocytes (8%) – destroy bacteria, viruses, and

toxins in blood

• Lymphocytes (33%) – provide immunity for the body

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Blood Components: White Blood Cells (cont.)

• WBC count normally 5000 to 10,000 cells per cubic millimeter of blood• Leukocytosis

• Elevated WBC count

• Usually due to infection

• Leukopenia • Low WBC count

• Some viral infections and other conditions

27-36

Blood Components: Platelets

• Fragments of cells found in the bloodstream

• Also called thrombocytes

• Important in the clotting process of blood

• Normal count• 130,000 to 360,000 platelets per cubic millimeter of

blood

27-37

Blood Components: Plasma

• Liquid portion of blood composed mostly of water

• Proteins• Albumins

• Smallest plasma proteins

• Pull water in to help maintain blood pressure

• Globulins – transport lipids and fat-soluble vitamins

• Fibrinogen – needed for blood clotting

• Nutrients• Amino acids

• Glucose

• Nucleotides

• Lipids from the digestive tract

• Gases – oxygen, carbon dioxide, and nitrogen

• Electrolytes

• Waste products

27-38

Blood: Bleeding Control

• Hemostasis – the control of bleeding

• Three processes of hemostasis• Blood vessel spasm

• Platelet plug formation

• Blood coagulation

27-39

Blood Types

• Types are distinguished by antigen and antibodies

• Agglutination• Clumping of red blood

cells

• Antigens on surface of RBCs bind to antibodies in plasma

27-40

Blood Types (cont.)

Blood Type Antigen

Present

Antibody

Present

Blood That Can

Be Received

A A B A and O

B B A B and O

AB AB None A, B, AB, and O

O None A and B O

27-41

Blood Types (cont.)

• Rh antigen – protein on RBCs

• Rh-positive• RBCs contain the

Rh antigen

• Rh-negative• RBCs do not contain

the Rh antigen

• Rh-positive blood is given to Rh-negative person

• Antibodies form

• If Rh-negative person receives more Rh-positive blood• Antibodies bind to the

donor cells

• Agglutination occurs

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Chest Pain

• Cardiac• Myocardial infarction

• Angina

• Pericarditis

• Coronary spasm

• Non-cardiac• Heartburn

• Panic attacks

• Pleurisy

• Costochondritis

• Pulmonary embolism

• Sore muscles

• Broken ribs

Take all complaints of

chest pain seriously!

27-43

Chest Pain (cont.)

• Determine cause• Electrocardiogram

• Stress tests

• Blood tests

• Chest x-ray

• Nuclear scan

• Coronary catheterization

• Echocardiogram

• Endoscopy

27-44

Diseases and Disorders of the Cardiovascular System

Disease Description

Anemia The blood does not have enough red blood cells

or hemoglobin to carry an adequate amount of

oxygen to the body’s cells

Aneurysm A ballooned, weakened arterial wall

Arrhythmias Abnormal heart rhythms

Carditis Inflammation of the heart

Endocarditis Inflammation of the innermost lining of the

heart, including valves

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Disease Description

Myocarditis Inflammation of the muscular layer of the heart

Pericarditis Inflammation of the membranes that surround

the heart (pericardium)

Congestive

Heart Failure

Weakening of the heart over time; heart is

unable to pump enough blood to meet body’s

needs

Coronary Artery

Disease (CAD)

Atherosclerosis; narrowing of coronary arteries

caused by hardening of the fatty plaque deposits

within the arteries

Diseases and Disorders of the Cardiovascular System (cont.)

27-46

Disease Description

Hypertension High blood pressure; consistent resting blood

pressure equal to or greater than 140/90 mm Hg

Leukemia Bone marrow produces a large number of

abnormal WBCs

Murmurs Abnormal heart sounds

Myocardial

Infarction

Heart attack; damage to cardiac muscle due to a

lack of blood supply

Diseases and Disorders of the Cardiovascular System (cont.)

27-47

Disease Description

Sickle Cell

Anemia

Abnormal hemoglobin causes RBCs to change

to a sickle shape; abnormal cells stick in

capillaries

Thalassemia Inherited form of anemia; defective hemoglobin

chain causes, small, pale, and short-lived RBCs

Thrombophlebitis Blood clots and inflammation develops in a vein

Varicose Veins Twisted, dilated veins

Diseases and Disorders of the Cardiovascular System (cont.)

27-48

Checkpoint!!!

ANSWER: Anemia is a condition in which a person does not have enough red blood cells or hemoglobin in the blood to carry an adequate amount of oxygen to body cells.

The doctor has told your patient she has anemia. How

would you explain this to the her?

27-49

In Summary

• Cardiovascular system• Transport system for body

• Heart, arteries, veins, and capillaries

• Blood• Transport medium

• RBCs, WBCs, platelets, plasma

• Medical assistant• Assists patients in understanding prevention and

treatments for cardiovascular problems

27-50

Lakô hã salamát!Maraming salamat!