Topic 2: Exercise physiology

2.2 Structure and function of the cardiovascular system

12 hours

Assessment Statements 1 2.2.1 State the composition of blood.

2.2.2 Distinguish between the functions of erythrocytes, leucocytes and platelets.

2.2.3 Describe the anatomy of the heart with reference to the heart chambers, valves and major blood vessels.

2.2.4 Describe the intrinsic and extrinsic regulation of heart rate and the sequence of excitation of the heart muscle.

2.2.5 Outline the relationship between the pulmonary and systemic circulation.

2.2.6 Describe the relationship between heart rate, cardiac output and stroke volume at rest and during exercise.

2.2.7 Analyse cardiac output, stroke volume and heart rate data for different populations at rest and during exercise.

Assessment Statements 2 2.2.8 Explain cardiovascular drift.

2.2.9 Define the terms systolic and diastolic blood pressure.

2.2.10 Analyse systolic and diastolic blood pressure data at rest and during exercise.

2.2.11 Discuss how systolic and diastolic blood pressure respond to dynamic and static exercise.

2.2.12 Compare the distribution of blood at rest and the redistribution of blood during exercise.

2.2.13 Describe the cardiovascular adaptations resulting from endurance exercise training.

2.2.14 Explain maximal oxygen consumption.

2.2.15 Discuss the variability of maximal oxygen consumption in selected groups.

2.2.16 Discuss the variability of maximal oxygen consumption with different modes of exercise.

2.2.1 Composition of BloodThe average adult human has ~5L

Plasma (55% of blood volume)1. Is the protein-containing fluid portion of the blood

containing a variety of dissolved materials including gases, nutrients and vitamins. The plasma also contains waste products and hormones. 

Cells (45% of blood volume)2. Red blood cells (RBCs) or erythrocytes

3. White blood cells (WBCs) or leukocytes

4. Platelets

5. Other proteins

2.2.2 Function of…Function

1 Red blood cells (RBCs) or erythrocytes

2 White blood cells (WBCs) or leukocytes

3 Platelets

What's the most active muscle in the body?

The human heart.

An absolutely remarkable organ. Obviously, its main function is to pump blood throughout the body.

On average, this muscular organ will beat about 100,000 times in one day and about 35 million times in a year. During an average lifetime, the human heart will beat more than 2.5 billion times.

2.2.3 Anatomy of the Heart

How does the Heart work?

blood from the body

blood from the lungs

The heart beat begins when the

heart muscles relax and blood

flows into the atria.

STEP ONE

The atria then contract and

the valves open to allow

blood

into the ventricles.

How does the Heart work?

STEP TWO

How does the Heart work?

The valves close to stop blood

flowing backwards.

The ventricles contract forcing

the blood to leave the heart.

At the same time, the atria are

relaxing and once again filling with

blood.The cycle then repeats itself.

STEP THREE

To think about…….Right

Atrium

Right Ventricle

Left Atrium

Left Ventricle

Valves

The heart has 4 chambers:

2 on the Right: received blood and 2 on the left: pumps the blood out

How does the heart pump?

What kind of blood does each side

pump?

Which side of

the heart is thicker

Blood flows through the heart in a specific pathway.

• oxygen-poor blood enters right atrium, then right ventricle

• right ventricle pumps blood to lungs

• oxygen-rich blood from lungs enters left atrium, then left ventricle

• left ventricle pumps blood to body

Blood flows through the heart in a specific pathway.

The heart pumps blood through two main pathways.

Pulmonary circulation occurs between the heart and the lungs.

oxygen-poor blood enters lungsexcess carbon dioxide and water

expelledblood picks up oxygen oxygen-rich blood returns to heart

2.2.5 Pulmonary and systemic circulation

Systemic circulation occurs between the heart and the rest of the body.

– oxygen-rich blood goes to organs, extremities

– oxygen-poor blood returns to heart

• The two pathways help maintain a stable body temperature.

2.2.5 Pulmonary and Systemic circulation…in summary…

pulmonary circulation: Part of the circulatory system that carries blood between the heart and lungs.

systemic circulation: Part of the circulatory system that carries blood between the heart and body.

The heart has four chambers: two atria, two ventricles.• Valves in each chamber prevent backflow of blood.

• Muscles squeeze the chambers in a powerful pumping action.

aortic valve

left atrium

mitral valve

left ventricle

septum

pulmonary valve

right atrium

tricuspid

right ventricle

Animation

Click here to do the test

SUMMARY

Copy and complete the following;Arteries take blood ______ from the heart. The walls of an artery

are made up of thick _________ walls and elastic fibers. Veins

carry blood ________ the heart and also have valves. The

_________ link arteries and veins, and have a one cell thick wall.

Blood is made up of four main things; ______, is the liquid part of

the blood; Red Blood Cells carry ______; White blood cells

protect the body from disease, and _________ assist in the

process of repair following injury..

External structure of the heart

Arteries, veins and capillaries

Look up this source and find out what they are and do.

What does constriction and dilation mean?

2.2.4 Regulation of the heart rate

Animation

First step: The SA node generates electrical impulse.

Second step: The electrical impulse spreads rapidly over the walls of the atria, causing the atria to contract simultaneously. The contraction of the atria helps push blood into the ventricles.

2.2.4 Control of heart rate

Third step: The impulse is picked up by a specialized group of cells in the right atrium wall called the Atrioventricular Node (AV node or AVN).

Fourth step: This impulse is carried to the fiber bundles in the ventricles. This causes the ventricles to contract

2.2.4 Control of heart rate

2.2.4 Control of heart rate

Last step: The location of nerve fiber bundles causes the ventricles to contract from the apex (bottom) up squeezing blood up and out.

SA node, or pacemaker, stimulates atria to contractAV node stimulates ventricles to contract

SA node

VA node

• In Summary………• The heartbeat consists of two contractions.

2.2.4 Describe the intrinsic and extrinsic regulation of heart rate and the sequence

of excitation of the heart muscle.

As much as the heart has its own pacemaker, it is also important to note that it is influenced by the Sympathetic and Parasympathetic branches of the autonomic nervous system, and by adrenaline.

What does this mean?

2.2.4 Describe the intrinsic and extrinsic regulation of heart rate and the sequence

of excitation of the heart muscle.The sympathetic division (excites) deals with

emergency situations. It prepares the body for “fight or flight.” Do you get clammy palms or a racing heart when you have to play a solo or give a speech? Nerves of the sympathetic division control these responses.

The parasympathetic division (calms) controls involuntary activities that are not emergencies. It slows down the heart rate.

Take the quiz

Stethoscope Find out how to use it

Find out where to use it for

ReviewGo to http://www.hippocampus.org/Biology

  Biology for AP*  Search for human circulatory system

2.2.6 Heart rate –cardiac output and Stroke

volume

The heart during exerciseHeart rate (or pulse rate) is the number of times your heart beats every minute.

It is expressed in beats per minute (bpm).

Resting heart rate varies from individual to individual and is affected by fitness.

The fitter you are, the lower your resting heart rate will be.

The average resting heart rate is about 70–75 bpm.

You can measure how fast your heart is beating by

taking your pulse.

This can be done at the wrist or the neck.

Count how many times your heart beats in 6 seconds and then multiply by 10.

Heart rate and exercise

the arteries supplying the muscles dilate.

Heart rate can also be altered by hormones such as adrenaline. The presence of adrenaline causes the heart rate to increase, allowing a quick response to danger.

These changes help to provide oxygen and glucose to muscles and remove carbon dioxide more quickly.

During exercise several changes occur:

the heart rate increases

the rate and depth of breathing increases

stroke volume × heart rate = cardiac output

Heart rate, stroke volume and cardiac output

Cardiac output is the amount of blood pumpedout of the left ventricle of the heart per minute.

Stroke volume is the amount of blood pumpedout of the left ventricle per beat.

What is the cardiac output of someone with a heart rate of 60 bpm and stroke volume of 90 ml?

The heart during exerciseDuring exercise, the body uses up oxygen and nutrients at a much faster rate. To keep the body supplied with what it needs, the heart beats faster and with greater force.

What do you think happens to the cardiac output?

This means that the heart rate and stroke volume increase.

Heart rate during exercise

2.2.8 Explain Cardiovascular drift.

We used to think that exercising at a steady level led to the body reaching a steady state, where the heart rate remained the same.

However, research has shown that it does not stay the same but instead increases slowly. This is Cardiovascular drift.

It is characterized by a progressive decrease in stroke volume and arterial blood pressure, together with a progressive rise in heart rate.

It occurs during prolonged exercise in a warm environment despite the intensity of the exercise remaining the same.

So why does it happen ???

2.2.8 Explain Cardiovascular drift.

It is suggested that cardiovascular drift occurs because when we sweat a portion of the lost fluid volume comes from the plasma volume.

The decrease in plasma volume reduces venous return and stroke volume.

An increase of body temperature results in a lower venous return to the heart, a small decrease in blood volume from sweating.

A reduction in stroke volume causes the heart rate to increase to maintain cardiac output. If CVD did not occur, a person would have to lower his/her intensity.

Katch, McArdle, Katch (2011)

In Summary….

Submaximal exercise for more than 15 minutes (endurance activities), particularly in the heat, produces progressive water loss through sweating and a fluid shift from plasma to tissues.

A rise in core temperature also causes a redistribution of blood to the periphery for body cooling.

The progressive decrease in plasma volume decreases central venous cardiac filling pressure that reduces stroke volume.

Stroke Volume Heart rate – to maintain a nearly constant cardiac output as exercise progresses.

Katch, McArdle, Katch (2011)

Cardio vascular drift

I tried to run as steadily as I could, to see the effects of cardiac drift over the course of 20 miles. Here's the result: The steady increase in heart rate is clear to see, but is even more graphically illustrated by looking at the average heart rate for each 2 mile section: 131, 135, 135, 138, 140, 141, 141, 142, 144, 146 

Next lessonDissection of the heart..

2.2.7 Analyze cardiac output, stroke volume and heart rate

Get into groups of 3 and research the following below.

data for different populations at rest and during exercise.

males, females, trained, untrained, young and old. You can use the Internet or look on p. 43 in your text.

***Recall of quantitative data is not expected***

2.2.7 Analyze cardiac output, stroke volume and heart rate

Males vs. Females Heart rate – lower in males than females Stroke volume – Lower in females than males (body size plays

a role) Cardiac output – Larger in females

Trained vs. Untrained Heart rate – trained has a lower heart rate at rest, same at

max Stroke volume – trained has larger stroke volume at rest and

max Cardiac output – about the same at rest and sub-max, but not

at maximum intensity levels, where the trained is larger.

Young vs. Old Heart rate – higher in children Stroke volume – lower in children than adults Cardiac output – smaller in children than adults

2.2.9 Systolic and diastolic blood pressure

What is Systolic?

The force exterted by blood on arterial walls during ventricular contraction.

What is Diastolic?• The force exerted by blood on arterial

walls during ventricular relaxation.

2.2.9 Systolic and Diastolic blood pressure

Blood pressure is a measure of the force of blood pushing against artery walls. – systolic pressure: left

ventricle contracts – diastolic pressure:

left ventricle relaxes

• High blood pressure can precede a heart attack or stroke.

Cardiac CycleSystole – contract, diastole - relax

The atria fill, then contract (atrial systole), pumping blood via the atrioventricular valves into the ventricles.

Then the ventricles contract (ventricular systole), causing the atrioventricular valves to shut and the semilunar valves to open, allowing blood out of the heart. 

This is followed by relaxation (diastole) of the ventricles, and the semilunar valves shut. The cycles then repeats itself. 

The lub-dub sound is when the atrioventricular valves shut and then the semi-lunar valves.

http://www-medlib.med.utah.edu/kw/pharm/hyper_heart1.html

Blood pressureBlood pressure is affected by a number of factors.

Age – it increases as you get older.

Gender – men tend to have higher blood pressure than women.

Stress can cause increased blood pressure.

Diet – salt and saturated fats can increase blood pressure.

Exercise – the fitter you are the lower your blood pressure is likely to be.

Having high blood pressure puts stress on your heart. It can lead to angina, heart attacks and strokes.

2.2.11 How does Systolic and diastolic blood pressure respond to dynamic and

static exercise

• What is Static Exercise?

• What is Dynamic Exercise?

2.2.11 How does Systolic and diastolic blood pressure respond to dynamic and

static exercise

• In dynamic exercise, the increase in cardiac output increases the pressure when the ventricles are contracting.  Thus, the systolic blood pressure increases progressively.  In comparison, the diastolic blood pressure remains relatively unchanged.  

• The diastolic blood pressure remains unchanged due to the fact that dynamic exercise uses many different muscles.  

• As a result of the increased activity of the muscles, heat is produced.  Therefore, blood vessels dilate in order to give off the heat produced from the contraction of muscles during dynamic exercise.  

• The increase in the radius of the blood vessels then decreases resistance and therefore allows the diastolic blood pressure to remain unchanged despite higher cardiac output.  

2.2.11 How does Systolic and diastolic blood pressure respond to dynamic and

static exercise

• During static exercise the heart rate increases, which results in greater cardiac output.  As a result, the systolic blood pressure increases. The diastolic blood pressure also increased because the resistance of the flow of blood increases since only the radii of selected blood vessels increase despite higher cardiac output.  

• Static exercise uses far less muscle groups than that used during dynamic exercise.  As a result, static exercise produces less heat since fewer muscles are contracting.  

 • Therefore, only the vessels of the targeted muscle group dilate due

to the fact that those are the only vessels where excess heat is being produced.  

• Blood vessels not in the targeted muscle group experience an increase in pressure since they do not dilate but still have more blood flowing through them as a result of increased cardiac output.  

FYI….Healthy veins and arteries

VEIN ARTERY

Research has shown that exercise protects

the inner lining of bloodvessels.

This lining ensures that the blood vessels can easily expandand contract to cope with different blood flows. The lining also produces a substance which prevents the build-up offatty deposit on the blood vessels.

Unhealthy blood vessels become harder and less flexible which can lead to

serious heart and circulation problems.

Blood pressureBlood pressure depends on the speed of the blood coming into a vessel and the width of the vessel itself.

Arteries

Speed: high

Width: medium

Pressure: high

Capillaries

Speed: medium

Width: narrow

Pressure: medium

Veins

Speed: low

Width: wide

Pressure: low

Appshttp://

itunes.apple.com/us/app/skeletal-3d-anatomy/id409279397?mt=8

2.2.12 Redistribution of blood during exercise

With exercise, metabolism speeds up and because of this the muscles require more oxygen

So the heart beats faster to supply the muscles with more oxygen-rich blood

In turn the speed of blood flow increases.

2.2.13 Cardiovascular adaptations resulting from endurance exercise training

Increased left ventricular volume

Increased stroke volume

Lower resting and exercising heart rate (why?)

Also: increased capillarization and increased arterio-venous oxygen difference (see next slide)

2.2.13 Arterio – Venous difference (A-VO2 diff)

• This is the difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles.

• At rest, the arterio-venous difference is low because the muscles do not need much oxygen.

• During exercise, however, the muscles need more oxygen from the blood, so the arterio-venous difference is high.

2.2.14: Vo2maxDefinition:

VO2 max is the maximal oxygen uptake or the maximum volume of oxygen that can be utilized in one minute during maximal or exhaustive exercise.

It is measured in L – min -1

VO2 max or maximal oxygen uptake is one factor that can determine an athlete’s capacity to perform sustained exercise and is linked to aerobic endurance.

It is generally considered the best indicator of cardiorespiratory endurance and aerobic fitness.

Elite endurance athletes typically have a high VO2 max. Some studies suggests that it is largely due to genetics, although training has been shown to increase VO2 max up to 20%. A major goal of most endurance training programs is to increase this number.

2.2.15 Discuss the variability of maximal oxygen consumption in selected groups

2.2.15 Group VO2max

(L MIN -1)Max HR

(B MIN -1)MAX SV

(ML B -1)MAX Q

(L MIN-1)

Mitral stenosis

1.6 190 50 9.5

Sedentary 3.2 200 100 20.0

Athlete 5.2 190 160 30.4

Modified from Rowell LB. Circulation. Med Sci Sports 1969: 1:15, as cited by McArdle, Katch & Katch (2007)

2.2.16 Discuss the variability of maximal oxygen consumption with different modes

of exercise

With a partner, research and compare the variability of VO2max with cycling, running and arm ergometry.

Vocabulary aorta: The largest artery; receives blood directly from the heart.

artery: Type of blood vessel that carries blood away from the heart toward the lungs or body.

blood pressure: Force exerted by circulating blood on the walls of blood vessels.

blood vessel: Vessel that transports blood; includes the arteries, veins, and capillaries.

capillary: Smallest type of blood vessel that connects very small arteries and veins.

constriction: Narrowing of the blood vessels; occurs when the muscular walls of blood vessels contract.

dilation: Widening of the blood vessels; occurs when the walls of blood vessels relax.

hypertension: High blood pressure.

inferior vena cava: The vein that receives blood directly from the heart.

superior vena cava: The vein that brings blood back to the heart from the upper body.

vein: Type of blood vessel that carries blood toward the heart from the lungs or body.

Cross word

Quiz

Resource to check knowledge

1. Choose the correct pathway through which air passes on its way from the

atmosphere to the alveolus.

1. Trachea → Bronchiole →Larynx → Bronchus

2. Larynx → Trachea → Bronchus → Bronchiole

3. Bronchiole → Bronchus → Larynx → Trachea

4. Bronchus → Bronchiole → Trachea → Larynx

2. Which combination of the following lung volumes would allow you to

calculate the residual lung volume?

1. Inspiratory reserve volume and tidal volume

2. Total lung capacity and expiratory reserve volume

3. Tidal volume and inspiratory reserve volume + expiratory reserve volume

4. Total lung capacity and vital capacity

3. What type of blood is pumped by each of the four chambers of the heart?

 Left atriumRight atrium

Left ventricle

Right ventricle

A  oxygenated oxygenateddeoxygenated deoxygenated

B deoxygenated

deoxygenated oxygenated oxygenated

C  oxygenateddeoxygenated oxygenated deoxygenated

D deoxygenated oxygenated

deoxygenated oxygenated

4. What is systolic blood pressure?

A.The pressure at the brachial artery when the ventricles relax

B.The pressure at the brachial artery when the ventricles contract

C.The pressure at the brachial artery when atria aid the filling of the ventricles

D.The relationship between stroke volume and heart rate

Answers 1= 2

2= 4

3= C

4= A

Short answer questions

1. Define the term systolic and diastolic blood pressure

2. Describe the relationship between the pulmonary and systemic circulation

3. Describe the relation between cardiac output, HR and stroke volume at rest and during exercise

Answers Systolic: the force exerted by blood on arterial walls during

ventricular contraction.

Diastolic: the force exerted by blood on arterial walls during ventricular relaxation.

Deoxygenated blood leaves the RV lungs and become oxygen rich

Oxygenated blood goes to heart (LA) (pulmonary circulation: heart – lungs - heart)

Oxygenated blood is pumped into the body where it delivers the O2

Deoxygenated blood enters the RV of the heart (systemic circulation: heart – body - heart)

During exercise: cardiac output increases because SV expands and HR goes up