1 the circulatory systemppt

8/11/2019 1 the Circulatory Systemppt

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Boardworks Ltd 20061 of 36

The Circulatory System


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KS4 Physical

Education


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Lea

rningo

bjective

s


Learning objectives

The functions of the circulatory system:transportation, control and protection

To identify cardiac structures

How the heart acts as a pump in the doublecirculatory system

Definitions of heart rate, stroke volume and cardiac

output

The roles of blood vessels in the circulatory system

How exercise and training effect the circulatory

system

The components of blood.

What we will learn in this presentation:


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The circulatory system

bodyscells

lungsDeoxygenatedblood is

pumped from

the heart to the

lungs through

the pulmonary

artery.

Oxygenatedblood returns

to the heart

through the

pulmonary

vein.

Oxygenated

blood is pumped

at high pressure

from the heart to

the body through

the aorta.

Deoxygenated

blood returns tothe heart

through the

vena cava.


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The double circulatory system

oxygenated blood to the rest ofthe body through the arteries

deoxygenated blood back to the

heart through the veins.

Thepulmonary circulationcarries:

deoxygenated blood from theheart to the lungs

oxygenated blood back from the

lungs to the heart, ready to be

pumped out to the body.

The systemic circulationcarries:

lungs

bodyscells


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The circulatory system


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Blood vessels

There are three typesof blood vessels, as shown in this

magnified part of the circulatory system.

Why are there different types of blood vessels?

blood fromthe heart

blood to theheart

arterycarries blood

back intothe heart

carries bloodaway fromthe heart

carries blood toand from thebodys cells

vein


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Blood vessels

thickouter wall

thickinner layer of muscleand elastic fibres

narrowcentral tube

(lumen)

thinouter wall

thininner layer of muscle

and elastic fibres

widecentral tube(lumen)

wall only one cellthick

ARTERY

VEINCAPILLARY


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Blood vessels: valves

When blood is flowing against gravity, or when a vein is

squeezed by muscle action, there is a risk that blood will flowin the wrong direction. Veinshavevalvesto prevent backflow.

bloodto theheart

backflowprevented

vein valveopenvein valve

closed

The valves allow

blood to flow in the

correct direction

but close if blood

starts to flow in the

wrong direction.


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Cardiac system

The four chambers of the heart have special names:

A lowerchamber is called a ventricle.

An upperchamber is called an atrium(plural: atria).

rightatrium

rightventricle

left

atrium

left

ventricle



Cardiac system

Here are some other important parts of the heart:

The wallsare made of

cardiacmuscle.

The walldividing the

left and

right sidesof the heartis called the

septum.

The semi-lunarvalvespreventexpelled blood

flowing back into

the heart.

These two valvesprevent blood flowing

back into the atria

from the ventricles.

Bicuspid

(mitral) valve

Tricuspid

valve


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The heart during exercise

Heart rate(or pulse rate) is

the number of times yourheart beats every minute.

It is expressed in beats per

minute(bpm).

Resting heart rate varies fromindividual 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 7075 bpm.

You can measure how fast

your heart is beating bytaking your pulse.

This can be done at the

wristor the neck.Count how many times your

heart beats in 6 seconds

and then multiply by 10.


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cardiac output = stroke volume heart rate

Heart rate, stroke volume and cardiac output

The pulse rate is not the only way of measuring the heart.

Cardiac outputis the amount of blood pumped

out of the left ventricle of the heart per minute.

Stroke volumeis the amount of blood pumpedout of the left ventricle per beat.

Cardiac output can be calculatedby multiplying the

stroke volume by the heart rate:

What is the cardiac output of someone with a heart

rate of 60 bpm and stroke volume of 90 ml?




During exercise, the body uses up oxygen and nutrients at a

much faster rate. To keep the body supplied with what itneeds, the heart beats fasterand with greater force.

This means that the heart rateand stroke volumeincrease.

What do you think happens to the cardiac output?

Regular exercise causes changes to the heart.

The heart gets larger

The muscular wall become thicker

and stronger

Stroke volume at rest increases,

leading to a lower resting heart rate.



Blood pressure



Blood pressure

Blood pressure depends on the speed of the blood coming

into a vessel and the width of the vessel itself.

Arter ies

Speed: high

Width: medium

Pressure:high

Capil laries

Speed: medium

Width: narrow

Pressure:medium

Veins

Speed: low

Width: wide

Pressure:low



Blood pressure

An individuals blood pressure is affected by a number of

factors.Ageit increases as you get older.

Gendermen tend to have higher blood

pressure than women.

Stresscan cause increased blood pressure.

Dietsalt and saturated fats can increase

blood pressure.

Exercisethe 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 attacksand strokes.



Effects of exercise on blood pressure

The immediate effect of exercise is to raisethe blood

pressure as the heart beats faster and more powerfully.

However, in the long-term,

regular exercise reducesblood

pressure. The fitter you are, the

lower your blood pressure islikely to be.

During intense exercise, blood flow to the muscles can

increase to 35 times its normal volume. Higher blood

pressure is necessary in order to get this extra blood to

the muscles.


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Blood flow and body temperature

If the body gets too cold, capillaries near the surface of the

skin get narrower. Blood is diverted away from the skin to

limit heat loss. This is called vasoconstriction.

Sweating stops.

CapillariesSweat

gland



Blood

Blood is the bodys means of transporting

substances around. It transports:

oxygenfrom the lungs to the heart and then to the

bodys tissues

carbon dioxidefrom the tissues to the heart and then

to the lungs to be expired

materials like hormonesfrom one organ to another

nutrients(especially glucose) and mineralsfrom the

intestines to the tissues

waste productsto the kidneys.



Blood



Red blood cells

Also called erythrocytes.

Disc-shaped.

Made in the bone marrow.

Contain a red-coloured

compound called haemoglobin

which bonds with oxygen to form

oxyhaemoglobin.

Transport oxygen to the tissues.

Blood is made up of a number of different elements.

The most common cell in blood is thered blood cell.

How important do you think red blood

cells are to sports performance?


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White blood cells

Also called leucocytes.They are bigger than red

blood cells and have large

nuclei.

Act as the bodys defencesystem.

Blood also contains white blood cells.

How important do you think white blood

cells are to sports performance?

Some white blood cells surround and consume

harmful microbes.

Some produce chemicals called antibodiesthat fight

infection.

Pl l


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Platelets

Formed in red bone marrow.

Produce thrombokinase

a chemical needed for blood

clotting.

Platelets help to repair tissues

and close woundsboth

internally and externally.

When needed, they grow into

irregular shapes and stick together

to form a plugover the wound.

Plateletsare also carried in the blood.

How important do you think platelets

are to sports performance?

Pl


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Plasma

90% water

inorganic salts

glucoseantibodies

urea and other waste products

plasma proteins.

The blood cells and platelets are suspended in a substance

called plasma. Plasma is made up of:

Plasma can be separated

from the other components

of blood using a centr i fuge.

plasma

Bl d ll


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Blood cells

R l f bl d i hi i t t ti l


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Role of blood in achieving sports potential

Because red blood cellscarry oxygen, which is vital to

muscle action, it is advantageous for a performer to have ahigh red blood cell count, especially in endurance events.

When athletes train and live at

altitude, where there is less

oxygen in the air, their bodiescompensate by producing extra

red blood cells.

This means that they can

perform at a higher intensity thanother athletes when performing

at sea level.

EMPICS Ltd

Bl d d i


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Blood doping

An athletes red blood cell count can be

illegallyboosted through blood doping.Several months before a competition,

blood is removed from a performer.

Their body produces more blood to replace

the blood that has been removed.

The red blood cells are separated out

from the removed blood and stored. Just before the

competition, they arere-injectedinto the competitor, giving

them an artificially high red blood cell count.

Blood doping can improve performance by 20%, however,

the extra blood can lead to dangerous blood clotsand all

the heart problems associated with high blood pressure.

E t l ti


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Exam-style questions

1. During exercise, extra demands are placed on the

circulatory system.a) Describe what happens to heart rate, stroke volume

and cardiac output during intensive physical activity.

b) Describe how the circulatory system helps to

regulate body temperature during exercise.

2. Blood contains several different types of cell.

a) Explain the function of red blood cells in the body.

b) Describe one way in which a performer couldincrease their red blood cell count.

Q i


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Quiz


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1 the circulatory systemppt

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