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The build of the heart, cardiac cycle

Source: BruceBlaus, Wikimedia Commons, licencja: CC BY-SA 4.0.

Link to the lesson

Before you start you should know
  • blood is a liquid tissue;

  • cardiovascular system of humans is a closed system of vessels;

  • blood participates in transporting nutrients and respiratory gases.

You will learn
  • to present the connection between how organs of the cardiovascular system are build and what their functions are;

  • you will talk about the cardiac cycle and how the heart is build;

  • you will compare the build and the functions of arteries, veins and capillaries;

  • you will describe the blood flow in the systemic and pulmonary circulation;

  • you will measure the pulse and compare it with the results of healthy people.

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Nagranie dźwiękowe abstraktu

The build of the heart

Cardiovascular system is a closed transporting system, which is composed of the heart and blood vessels. HeartheartHeart has the shape of a cone and the size of a closed fist. It is found in the middle of the chest, behind the sternum, and its tip is pointed to the left. It is composed of striated muscle tissue, which contracts regularly, forcing the blood to flow in blood vessels. There are 4 chambers of the heart: 2 atriaatriumatria (right and left) and 2 ventriclesventricleventricles (right and left). There are walls between particular parts of the heart. The walls of the ventricles are thicker and more muscular than the walls of the atria. This happens because the atria transport the blood only to the ventricles, and the ventricles transport it into all the arteries. The pressure of the blood pushed out by the ventricles must be this high in order for the blood to reach even the cells that are located the furthest from the heart. VeinsveinsVeins enter into the atria and transport blood into the heart, whereas arteriesarteriesarteries start from the ventricles and they transport the blood from the heart. Between the atria and the ventricles and at the place where the vessels exit the ventricles there are valvesvalvevalves. They open in one direction only, which means they force the blood to flow in one direction and prevent it from regressing.

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Simplified schematic drawing of the heart
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.

In order to describe how heart works using a schematic drawing, we must first establish, which part is left and which part is right. In order to do this, we put the piece of paper with the schematic drawing of a heart to our own torso, as if we wanted to show the model of our own heart. The parts of the schematic drawing of the heart on our left side are the left ventricle and left atrium, and those on our right side – right ventricle and right atrium.

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The location of the heart
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.
Task 1

Left ventricle has thicker walls than the right one. Explain, what is the cause of this difference.

How the heart works

If blood isn’t reaching an organ for several minutes, that place suffers from irreversible changes and necrosis of tissues, which is why the heart beats non‑stop. Heart beat is composed of contractions of the organ, one after the other. A doctor listens to cardiac cycle when putting stethoscope to our chest. He pays attention e.g. to the tones, which approximately are identical with contractions of the ventricles and them unflexing.

First, blood transported by the veins fills both atria. When the atria contract, they push blood into the chambers. Then, both ventricles contract, pushing the blood from the heart into the arteries. After that, heart has a short period of rest. When it is relaxed, the atria become filled with blood again.

The heart contracts between 60 and 80 times per minute, pushing around 80 cmIndeks górny 3 of blood during every contraction. The pressure of the blood flowing from the heart can be felt in the arteries as pulsepulsepulse and measured with a blood‑pressure device. This device shows you the values of systolic pressuresystolic pressuresystolic pressure (120 mm Hg) and diastolic pressurediastolic pressurediastolic pressure (80 mm Hg). Blood pressure is measured during rest, because it becomes elevated during effort. The values of the pressure can change, depending on the physical activity, emotional state, temperature and food that we consumed.

Contracting heart works, which is why it requires large amounts of energy. This is why it has its own network of blood vessels called coronary arteries. They provide each cell of the heart muscle with elements necessary for cellular respiration. Cardiac cycle does not depend on us. The heart has a natural pacemaker, composed of highly specialized cells, which have the ability to move the heart muscle and make it contract.

Observation 1

Listening to the heart beat.

You will need
  • you,

  • stethoscope,

  • a stopwatch.

Instruction
  1. Put the stethoscope to your chest, at a heart level. Hold your breath for a while. Listen to the cardiac cycle.

  2. Try to recall heartbeat by tapping it. Assign specific taps and pauses the stages of cardiac cycle.

  3. Count how many beats your heart makes within a minute.

Task 2

After you performing the Observation 1 write down the research question and the hypothesis, observations and finally – conclusions.

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Analysis:. Research question (Uzupełnij). Hypothesis (Uzupełnij). Observations (Uzupełnij). Conclusions (Uzupełnij).
Task 3

Explain, why during the listening to the heart beat the doctor says the following: “Do not breathe”.

Task 4

Anazyle the results presented in the table. Based on them, form a conclusion.

Age

Number of heartbeats per minute

newborn baby

140 - 160

1 year old

110 - 130

5 years old

100 - 110

8 years old

90 - 100

Observation 2

Searching for arteries and measuring the pulse.

You will need
  • you,

  • a stopwatch.

Instruction
  1. Sit comfortably. Using your index and middle fingers of the right hand search on the left side of the trachea for the carotid artery.

  2. Feel the pulse with your fingers. Count pulse during 30 seconds, multiply the result by 2.

  3. With your index finger and middle finger try to find the pulse on the radial artery above the wrist on the thumb side. Measure the pulse, the result is expressed in the number of beats per minute.

  4. Compare the results.

  5. Learn how to feel the pulse on the radial arteries of your classmates.

  6. Explain, in which situation you can use this skill.

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Heart rate measurement points
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.
Summary

Pulse is the rhythm in which blood is moved into the arteries by the left ventricle, it basically equals the frequency of the contractions of that ventricle. Arteries are usually hidden between tissues which give them protection against injuries and pressure.

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Exercise 1
Select the correct sentences. Możliwe odpowiedzi: 1. Clavicle is the bone that protects the heart., 2. Heart is situated in the middle of the chest under the sternum, that is in the middle part of the lung cavity., 3. The heart is situated on the left side of the chest with the tip pointed to the right., 4. The heart, just like other internal organs,is made of a smooth muscle tissue., 5. The work of a heart muscle does not depend on our will.
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Exercise 2
Wybierz dowolne angielskie słówko ze słowniczka i zapytaj kolegę o jego znaczenie.
Source: Tomorrow Sp. z o.o., licencja: CC BY 3.0.
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Exercise 3
Select the correct sentences. Możliwe odpowiedzi: 1. Veins lead blood to the heart, whereas arteries lead blood from the heart., 2. Valves are located between the atriums and the ventricles, the ventricles and the arteries., 3. The wall of the left ventricle is thinner than the wall of the right ventricle., 4. The biggest artery of the body, aorta, begins in the left ventricle., 5. The pulmonary artery starts in the right ventricle., 6. The pulmonary artery reaches the left atrium.
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Exercise 4
Choose the correct ending of the following phrase. On the schematic drawing of the heart: Możliwe odpowiedzi: 1. the blue colour indicates blood that is rich in oxygen., 2. the red colour indicates oxygenated blood., 3. the blue colour indicates arteries., 4. the red colour indicates veins.
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Exercise 5
Blood deprived of oxygen is in the main vein. Put the elements of heart and blood vessels in the correct order so that you can show the movement of blood in the right part of the heart. Elementy do uszeregowania: 1. valve, 2. right ventricle, 3. valve, 4. pulmonary artery, 5. right atrium
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Exercise 6
Blood rich in oxygen is in pulmonary vein. Put the elements of heart and blood vessels in the correct order so that you can show the movement of blood in the left part of the heart. Elementy do uszeregowania: 1. valve, 2. left atrium, 3. valve, 4. aorta, 5. left ventricle
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Exercise 7
Choose the correct sentences. Listening to how the heart works we know that Możliwe odpowiedzi: 1. the first beat means that the atriums contract, 2. the first beat means pumping blood into the ventricles, 3. the second beat means that the ventricles contract, 4. the second beat means that the blood enters the arteries, 5. pause means how long the heart rests, 6. pause means the time when the ventricles fill up.

Summary

  • Cardiovascular system includes the heart and blood vessels: Veins, arteries and capillaries.

  • Heart is the suction and forcing pump, that makes the blood move in the vessels.

  • Human heart is divided into 4 parts: 2 atria and 2 ventricles.

  • Valves that are present in the heart and in veins force the blood to flow in one direction only.

  • Arteries lead blood from the heart, whereas veins lead blood to the heart.

  • Capillaries are wrapped around cells, provide them with nutrients and participate in gas exchange.

Homework
Task 5.1

Select a blood vessel connected directly to the heart in which the blood has a lot of oxygen and little nutrients.

Select a blood vessel connected directly to the heart in which the blood has a lot of oxygen and little nutrients.

Keywords

heart, valves, aorta

Glossary

aorta
aorta
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Nagranie dźwiękowe słówka

aorta – największa tętnica organizmu; wyprowadza krew z lewej komory serca, należy do dużego obiegu krwi

diastolic pressure
diastolic pressure
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Nagranie dźwiękowe słówka

ciśnienie rozkurczowe – ciśnienie krwi panujące w tętnicach podczas rozkurczu komór serca wyrażane w mm Hg

systolic pressure
systolic pressure
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Nagranie dźwiękowe słówka

ciśnienie skurczowe – ciśnienie krwi panujące w tętnicach podczas skurczu lewej komory serca wyrażane w mm Hg

ventricle
ventricle
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Nagranie dźwiękowe słówka

komora – jedna z 4 jam serca zaopatrzona w silnie umięśnione ściany, których skurcz wypycha krew do krwiobiegów – dużego (lewa komora) lub małego (prawa komora)

deoxygenated blood
deoxygenated blood
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Nagranie dźwiękowe słówka

krew odtlenowana – krew uboga w tlen, bogata w dwutlenek węgla

oxygenated blood
oxygenated blood
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Nagranie dźwiękowe słówka

krew natleniona – krew bogata w tlen, uboga w dwutlenek węgla

systemic circulation
systemic circulation
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Nagranie dźwiękowe słówka

krwiobieg duży – inaczej krwiobieg ustrojowy; system naczyń krwionośnych rozpoczynający się w lewej komorze, prowadzący krew tętnicami w kierunku narządów ciała (innych niż płuca), gdzie zachodzi wymiana gazowa wewnętrzna; krew pozbawiona tlenu wraca do serca żyłami do prawego przedsionka

capillaries
capillaries
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Nagranie dźwiękowe słówka

krwiobieg mały – inaczej krwiobieg płucny; system naczyń krwionośnych rozpoczynający się w prawej komorze, prowadzący krew tętnicami w kierunku płuc, gdzie zachodzi wymiana gazowa zewnętrzna; krew naleniona wraca do serca żyłami płucnymi do lewego przedsionka

atrium
atrium
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Nagranie dźwiękowe słówka

przedsionek – jedna z 4 jam serca, do której spływa krew z krwiobiegu dużego (prawy przedsionek) lub małego (lewy przedsionek)

heart
heart
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Nagranie dźwiękowe słówka

serce – główny narząd układu krwionośnego zbudowany z tkanki mięśniowej poprzecznie prążkowanej serca; działa jak pompa ssąco‑tłoczącai wymusza krążenie krwi w naczyniach krwionośnych

arteries
arteries
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Nagranie dźwiękowe słówka

tętnice – naczynia krwionośne transportujące krew z serca (komór) w kierunku komórek ciała

pulse
pulse
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Nagranie dźwiękowe słówka

tętno – puls; rytmiczne rozciąganie ścian tętnic przez krew wypchniętą podczas skurczu serca i płynącą falami pod wysokim ciśnieniem

valve
valve
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Nagranie dźwiękowe słówka

zastawka – błoniasty fałd występujący w przegrodzie serca między przedsionkami i komorami oraz w żyłach i naczyniach limfatycznych; wymusza jednokierunkowy przepływ krwi w sercu i innych naczyniach

veins
veins
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Nagranie dźwiękowe słówka

żyły – naczynia krwionośne zaopatrzone w zastawki; transportują krew z komórek ciała do serca (przedsionków)