THESTRUCTURE OF THE CARDIOVASCULAR...

© 2015 Thompson Educational Publishing, Inc. 1

THE STRUCTURE OF THE

CARDIOVASCULAR SYSTEM

• 250-350g• Left of the

midline• Size of a

closed fist• Two sides are

separated by the septum

The pericardium is the fluid filled sac that surrounds and protects the heart and its great vessels.

Pericardium-protective sac around the heart

The Heart Acts as a “Double Pump”


Myocardium

•Specialized muscle tissue (cardiac muscle) that forms the

heart. The heart is considered a “double pump” that is

divided into right and left sides.

Pulmonary circulation

•The main function of the right side of the heart is to

pump deoxygenated blood, which has just returned to

the body, to the lungs.

Systemic circulation

•The role of the left side of the heart is to pump

oxygenated blood, which has just returned from the

lungs, to the rest of the body.

Arteries and Veins


Arteries are blood vessels that carry blood away from the

heart.

• In the systemic circulation, arteries carry oxygenated blood

from the left side of the heart towards body tissues. In the

pulmonary circulation, arteries carry deoxygenated blood

from the right side of the heart towards the lungs.

Veins are blood vessels that carry blood towards the

heart.

• In the systemic circulation, veins carry deoxygenated blood

towards the right side of the heart from body tissues. In the

pulmonary circulation, veins carry oxygenated blood

towards the left side of the heart.

Other Vascular Structures


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Arterioles

• Arterioles are vessels in the

blood circulation system that

branch out from arteries and

lead to capillaries, where gas

exchange eventually occurs.

Capillaries

• The smallest of the blood vessels,

capillaries help to enable the

exchange of water, oxygen, carbon

dioxide, and other nutrients and

waste substances between blood

and the tissues of the body.

Overview of the Human Vascular System


2

Atria and Ventricles

Atria and Ventricles

The heart is made up of four chambers (two sides). The

upper chambers are called atria (singular: “atrium”), and the

lower chambers are called ventricles. Blood is received into

the atria and pushed out from the ventricles.


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Major Structures of the Heart


4

The Flow of Blood through the Heart


5

Blood is delivered to the right atrium from the

superior and inferior vena cava. It passes through

the tricuspid valve and enters the right ventricle.

From there, the blood is pumped through the

pulmonary semilunar valve and out through the

pulmonary arteries to the lungs.

The blood returns from the lungs through the

pulmonary veins to the left atrium. It then passes

through the bicuspid valve and enters into the left

ventricle. The blood is then pumped out through the

aortic semilunar valve into the aorta and throughout

the systemic circulation.

Tracking the Flow of Blood


The Skeletal Muscle Pump

•The low pressure within

the veins causes a

problem for the

cardiovascular system.

•The skeletal muscle pump

aids in the return of blood

back to the heart through

the veins.

•With each contraction of

the skeletal muscle, blood

is pushed back to the

heart.


Pressure in veins (in the chest) decrease while pressure in veins (in the abdominal cavity) increase upon intake of breath

Difference in pressure pushes blood from veins in the abdominal cavity into veins in the thoracic cavity

Nervous system sends a signal to the veins to

constrict

Veins constrict allowing more blood back to the heart

Two main components:

Plasma

Fluid component of blood (mostly water)

Formed Elements

Red blood cells (erythrocytes)

Made in bone marrow

Transport O2 and CO2 in the blood

Transport nutrients and waste

Contain hemoglobin

White blood cells (leukocytes)

Destroy foreign elements

Critical in the function of the immune system

Platelets

Regulate blood clotting

Plasma 55%90% water

7% plasma proteins

3% other (acids,

salts)

Formed elements

45%>99% red blood cells

<1% white blood cells

and platelets

Buffy Layer

The Cardiac Cycle


• The cardiac cycle is the series of

events that occurs through one heart

beat. During this cycle there is both a

phase of relaxation (diastole), in

which the ventricle is filling with

blood, and a phase of contraction

(systole), in which the heart

contracts and ejects the blood.

• Blood pressure is the force exerted

by the blood against the walls of the

arteries and other vascular vessels.

Blood pressure in each of the two

phases—diastole and systole—is

measured in millimetres of mercury

(abbreviated as mmHg).

Systolic and Diastolic Blood Pessure


When blood pressure is reported or

measured, it is often stated as being the

systolic pressure over the diastolic

pressure (e.g., 120/80 mmHg).

Systolic blood pressure

• refers to the maximum pressure

observed in the arteries during the

contraction phase of the ventricle (e.g.,

120 mmHg).

Diastolic blood pressure

• is the minimum pressure observed

in the arteries during the

relaxation phase of the ventricle

(e.g., 80 mmHg).

Normal Blood Pressure

120/80 mmHg

High Blood Pressure: (hypertension)

140/90 mmHg or higher

Low Blood Pressure: (hypotension)

90/60 mmHg

The Heart’s Electrical Conduction System


The cardiac muscle cells are excitable, meaning that with electrical

stimulation they will all contract (this is known as a “syncytium”).

Within the heart there are areas of specialized tissue that are

important in the regulation and coordination of this electrical

activity.

These specialized tissues are:

• the sinoatrial node (SA node)

• the atrioventrical node (AV node)

The contraction of the heart leads to the pumping of blood.

The Heart’s Electrical Conduction System


The sinoatrial node (SA node)

• This is a specialized region of tissue that is

found in the right atrium where electrical

signals that lead to contraction are initiated

(also called the “pacemaker” of the heart).

The atrioventrical node (AV node)

• This is the specialized tissue that transmits the

electrical signal from the atria into the

ventricles and to a region that runs down the

ventricular septum. The ventricular septum is

the tissue that separates the two ventricles

(the bundle of His, also known as the

atrioventricular bundle).


Cardiac conduction

An Electrocardiogram


Measured using an electrocardiogram (ECG) or EKG

Graphical representation of electrical sequence of events occurring with each contraction of the heart

Current on body surface derived almost entirely form heard

12 tracings or leads

Normal sinus rhythm: 60-100 bpm

Bradycardia: < 60 bpm, conditioned athlete, drugs, hyopothermia, sleeping

Tachycardia: > 100 bpm, exercise, smoking, fever, hypoxia (lack of O2 to brain)

ST segment elevation -represents tissue injury due to acute, prolonged reduction in BF. May show up min or hours after a heart attack (due to clot or vascular coronary spasm)

Inverted T wave: represents ischemia (temporary and reversible reduction in blood flow; may show up hours or days after ischemic attack)

Abnormal Q wave: irreversible death of heart tissue

Myocardial infarction: heart attack

-occurs when an artery that feeds the heart becomes blocked

Angina: chest pains

Ischemia: insufficient blood flow to provide adequate oxygenation. (ischemia leads to hypoxia)

Hypoxia: reduction of oxygen supply to tissues

Stroke: lack of oxygen to the brain

http://en.wikipedia.org/wiki/File:Ischemia.JPG

http://en.wikipedia.org/wiki/File:Ischemia.JPG

Heart Rate (HR): is the

number of times the

heart contracts in a

minute (bpm)

Avg. HR @ rest

=72bpm

Highly trained

athlete=40bpm

During intense exercise

HR may increase to up

to 200 bpm

Maximum HR=220-age

The lowest resting heart beat on

record is 28 bpm and belongs to

the cyclist Miguel Indura in

(Spain) who was tested at the

University of Navarra,

Pamplona, Spain, in 1995.

Lance Armstrong-his heart is 30

percent larger than average;

however, an enlarged heart is a

common trait for many other

athletes. He has a resting heart

rate of 32-34 beats per minute

(bpm) with a maximum heart

rate of 201 bpm.

Activity Heart RateSpeed skater

Downhill skier

Cyclist

Distance runner

Sprint athlete

Tennis player

Shooter

1-Highest

7-Lowest

2

3

4

5

6

Bradycardia and Tachycardia


Regular aerobic exercise results in

improvements in the efficiency of

the cardiovascular system at rest

and during exercise.

• Bradycardia is one of the most easily

observed adaptations that occurs with

training. Bradycardia is characterized

by a heart rate of 60 beats per minute

or less at rest, while tachycardia is a

heart rate of more than 100 beats per

minute at rest.

•Generally, a lower heart rate is

regarded as an indication of an

athletic or strong heart.

The Effects of Exercise


During exercise, dramatic changes ocur in the cardiovascular

system—changes known as cardiovascular dynamics.

The heart and the vessels constantly adapt to accommodate the

ever-changing requirements of the body during exercise.

Some of the factors that are considered when discussing

cardiovascular dynamics are:

• Cardiac output (Q),

• Blood pressure (BP),

• Distribution of blood flow, and

• Oxygen consumption (VO2).

-Regular aerobic exercise leads to

alterations of the cardiovascular

system

-These are functional & structural

With exercise the size and mass

of heart increase

Ventricular walls become thicker

and volume of ventricle increases

(due to increase in venous return)

This leads to a more forceful

contraction= increase in stroke

volume= increase in cardiac

output

Increase in number of capillaries that deliver blood to the heart tissue

Possible increase in the diameter of the coronary arteriesincrease in O2 to the heart in order to work harder

Increase in blood volume up to 15% within 2 days

This causes increase in venous return= increase in stroke volume (volume of blood ejected by left

ventricle per beat) = increase in cardiac output (the volume of blood pumped out of left

ventricle in 1 min)

Capillaries around the soleus muscle.

Cardiovascular system adapts to meet the demands that are placed on it

Heart adjusts amount of blood pumped by altering:

Heart rate (HR) (beats/min)

duration of each cardiac cycle

Stroke volume (SV) (mL)

volume of blood ejected by left ventricle per beat

Avg=70 mL per beat

Cardiac output (Q) (L/min)

HR SV = Q

The volume of blood pumped out of left ventricle in 1 min

Frank-Starling Law:

Ability of the heart to stretch and increase the force of contraction

Q (L/min)=SV (mL) x HR (bpm)

Q = SV x HR

Eg. An avg. HR at rest would be 72 bpm and an avg. SV at

rest would be 71 mL.

Therefore using the equation for Q = SV x HR Q= 71mL x 72 bpm

Q= 5040 mL/min or 5.04 L/min.

During exercise Q can increase to 15-25 L/min

depending on the intensity of exercise

Athletes tend to have slower HR and large SV creating a

more efficient circulatory system.

A slower HR with an increased SV requires less oxygen.

Cardiac Output during Exercise


The Cardiovascular Effects of Training


Heart Disease


The system of vessels that supply essential materials

via blood to the heart muscle itself is called the

coronary circulation.

Serious health repercussions and even death can

occur if a narrowing or blockage of blood vessels

restricts the flow of blood to the heart muscle. For

example, a heart attack (myocardial infarction) can

result when blood flow to a section of the heart

muscle becomes blocked due to plaque buildup or

some other reason.

The Coronary Vessels (Anterior View)


Atherosclerosis

• Coronary artery disease (also known as atherosclerosis) involves a

gradual narrowing of the coronary arteries resulting from the

accumulation of hard deposits of cholesterol (plaque), on the lining

of the blood vessels.


The Causes of Coronary Artery Disease


• Poor Diet,

• Smoking,

• Elevated blood lipids,

• Hypertension,

• Family history, and

• Physical inactivity.

Each factor individually increases the risk of development of coronary artery

disease. When the factors are combined, the risk of coronary artery disease is

magnified.

angioplasty

stent

The Functions of the Respiratory System

The three main functions

of the respiratory system

are to:

•Supply O2 to the

blood,

•Remove CO2 from the

blood, and

•Regulate blood pH (acid-

base balance).


Respiration


External Respiration

• External respiration refers to the processes that occur within the

lungs involving the exchange of O2 and CO2.

Internal Respiration

• Internal respiration refers to the exchange of gases at the tissue

level, where O2 is delivered and CO2 is removed.

Cellular Respiration

• Finally, cellular respiration is the process in which the cells use O2 to

generate energy in the mitochondria of cells.

The Structure of the Respiratory System

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The respiratory system can be

divided into two main zones — the

“conductive zone” and the

“respiratory zone.”

• The conductive zone

transports filtered air to the

lungs. This zone consists of the

mouth and nose; pharynx;

larynx; trachea; primary and

secondary bronchi; and tertiary

bronchioles and terminal

bronchioles.

• The respiratory zone is where gas

exchange occurs. Bronchioles,

alveolar ducts, and the alveolar sacs

are all structures of the respiratory

zone that are involved with the

exchange of gases between inspired

air and the blood.

The Mechanics of Breathing


The combination of inspiration and

expiration together is known as

“ventilation.”

• Inspiration is an active process,

requiring the contraction of various

respiratory muscles and therefore

the expenditure of significant

amounts of energy.

• Expiration, on the other hand, may be

passive, as in quiet breathing (which

may not require much energy) or

active (as in forced breathing).

Inspiration

Air flows into

the lungs due to

increased lung

volume following

the contraction

of the diaphragm

and intercostal

muscles.


Expiration

Air is expelled from

the lungs due

to relaxation of the

diaphragm and the

intercostal

muscles.


• Ventilation (VE) is the volume

of air moved by the lungs in 1

min.

• Influenced by two factors:

• Tidal volume (VT)

• Volume of air in each breath

• Respiratory frequency (f)

• Number of breaths taken per

minute

Ve is influenced by:

VT (tidal volume): vol. of air in each breath

f (respiratory frequency): # of breaths taken per min

@ rest VT = 0.5 L/breath

@ Exercise VT= 4 L/breath

@ rest f = 12 breaths/min

@ Exercise f = 40 breaths/min

Therefore, Ve = VT x f

note: during strenuous xcise, Ve = 200 L of air per

min

Gas Exchange


The average person’s

lungs have about 300

million alveolar sacs (that

is about a tennis court’s

worth), each of which is

surrounded by a web of

capillaries.

•The walls of each

capillary are one

cell thick, which

provides a very

short distance for

gases to diffuse.

Diffusion


The primary factor that mediates gas

exchange both at the lung (where

blood becomes oxygenated and CO2

is removed) and at the tissue (where

O2 is delivered for metabolism and

CO2 is removed) is diffusion.

• Diffusion is the movement of a

gas, liquid, or solid from a region

of high concentration to a region

of low concentration through

random movement.

• Diffusion can only occur if a

difference in concentration

exists, and such a difference is

called a concentration

gradient.

O2 Transport


O2 Transport

• The process by which O2 is absorbed in the lungs and carried to the

peripheral tissues.

CO2 Transport

• The process by which CO2 in blood is moved into the alveoli and

then exhaled from the body.

a-vO2 diff

• The difference between the amount of O2 in the artery and vein

reflects the amount of O2 that was delivered to the muscle.

Monitoring Cardiorespiratory Functioning


The Rest-to-Exercise Transition


The delivery of O2 to the working skeletal muscle is

achieved through a combination of physiological

mechanisms. However, this is not instantaneous. During

this “lag,” a phenomenon called oxygen deficit (O2 deficit)

occurs.

Oxygen deficit is the difference between the oxygen

required to perform a task and the oxygen actually

consumed prior to reaching a new steady state.

•The trained individual will reach this steady-state

plateau faster than an untrained individual.

Oxygen Deficit: difference between total oxygen

consumed during exercise and amount that would

have been used at steady-rate of aerobic metabolism.

--Trained person reaches steady-rate quicker, has smaller oxygen deficit.

Light aerobic exercise

rapidly attains steady-rate

with small oxygen deficit.

Moderate to heavy

aerobic takes longer to

reach steady-rate and

oxygen deficit

considerably larger.

Maximal exercise

(aerobic-anaerobic) VO2

plateaus without matching

energy requirement.

Excess post-exercise oxygen consumption: The extra oxygen required to replenish oxygen to the various systems that were taxed during the exercise.

Eg: refilling phosphocreatine reserves, replenishing O2 in blood and tissues, lowering breathing rate, lowering body temp. and increasing blood lactate removal.

Active recovery can aid in the removal of blood lactate.

O2 Deficit

Ventilatory threshold

• A state in which

ventilation

increases much

more rapidly than

workload

Lactate threshold

• The point where

blood lactate

concentrations

begin to increase


o Ve increases more rapidly than workload

o 65-85% VO2max

o increase Ve due to increase in lactic acid, and

therefore there is a decrease in blood pH

(increase in H+ ions in blood)

o increase in Ve, increases expelling of CO2 and

increases H+ to combine with bicarbonate to

form CACO2 + H2O, therefore decrease in H+

ions increases pH to normal levels,

therefore, increase in Ve aids to return blood Ph to

normal

Onset of Blood Lactate Accumulation

When lactate levels begin to accumulate rapidly in the blood, this is referred to as the

onset of blood lactate accumulation (OBLA).

• With training, the curve for lactate threshold and OBLA can shift to the right.


VO2max

Maximal rate of

oxygen

consumption

(VO2max)

VO2max is the maximum volume(V) of oxygen (O2) inmillilitres that the humanbody can use in oneminute, per kilogram of body weight, while breathing air at sea level.


VO2max Scores for Athletes/Non-Athletes


Physiological Adaptations to Training


Physiological Adaptations to Training


Respiratory Diseases


Asthma is a disease that is characterized

by spasm of the smooth muscles that line

the respiratory system, an oversecretion

of mucous, and swelling of the cells lining

the respiratory tract.

• Many factors can lead to an asthma

attack, including exercise, allergic

reaction, contaminates, and stress.

Fortunately, most cases of asthma

can be controlled through the use

of different medications.

• Some Olympic-level athletes have

been diagnosed with asthma and

yet are able to compete

internationally.

Asthma Continued

In people with asthma, the airways are chronically inflamed.

Certain triggers can make the inflammation worse and cause a

narrowing of the airways. At the same time, the body may

produce extra mucus that clogs the airways. These changes

work together to restrict the flow of air to the lungs. As too little

air gets through, wheezing and breathlessness occur.

Respiratory Diseases


Chronic obstructive pulmonary

disease (COPD) is a general term

that describes a family of diseases

that lead to a dramatic reduction in

airflow through the respiratory

system.

• Individuals with COPD cannot

perform normal everyday

activities without experiencing

dyspnea (shortness of breath).

• Treatment of COPD conditions

includes not only medications but

also supplemental oxygen therapy

for severe cases, as well as

respiratory muscle training.


A Diseased Lung

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