Heart disease, exercise and circulation

Lerne es beim Spielen

Beantworte diese Fragen für Energie, dann angle und erkunde. Kein Konto nötig.

Für Lehrkräfte: sofort einsetzbare Lektionsfolien, Lernnotizen für Heart disease, exercise and circulation (MYP Biology, Year 5) — nutze sie in deiner Lektion oder starte das Thema als interaktive Klassenaktivität, die deine Lernenden als Live-Spiel spielen.

Lektionsnotizen

Big idea: a pump that works for a lifetime, and what can go wrong

Big idea (key concept): Systems. The heart, the blood vessels and the blood form one transport system. If one part is damaged, the whole system, and the cells that depend on it, are affected.
Related concept: Consequences. Choices, genes and age change the chance of heart disease. In this topic you will weigh up evidence for the consequences of risk factors, and for the consequences of treatments.
Global context: Identities and relationships. Heart health is shaped by how people live, by their families and by the communities and health services around them. Cardiovascular disease is one of the leading causes of death in the world.
The double circulation. The right side of the heart pumps deoxygenated blood to the lungs (the pulmonary circulation). The left side pumps oxygenated blood to the rest of the body (the systemic circulation). Blood passes through the heart twice on each full circuit.
The left ventricle has a thicker muscular wall than the right ventricle because it pumps blood at higher pressure around the whole body. Valves between the chambers and in the exits stop blood flowing backwards.
Arteries carry blood away from the heart at high pressure and have thick, elastic, muscular walls. Veins carry blood back to the heart at low pressure, have thinner walls and valves. Capillaries have walls one cell thick so that substances can be exchanged with the tissues.

Inside the heart: chambers, valves and blood flow

Coronary heart disease

The heart is made of cardiac muscle. Its thick wall cannot get enough oxygen and glucose by diffusion from the blood inside the chambers, so it has its own blood supply: the coronary arteries, which branch from the aorta and run over the surface of the heart.
Coronary heart disease (CHD) happens when the coronary arteries become narrowed. Fatty material, including cholesterol, builds up in the artery wall as atheroma (plaque). The lumen (the space inside) gets smaller, so less blood reaches the heart muscle.
If the muscle gets too little oxygen when it works hard, it can cause chest pain called angina. The muscle cells respire anaerobically and the pain goes when the person rests.
If an atheroma breaks open, a blood clot can form and block the artery completely. The part of the heart muscle that the artery supplied gets no oxygen or glucose, and its cells begin to die. This is a heart attack.
The chain is: atheroma builds up, the artery narrows, a clot blocks it, muscle is starved, cells die. A larger blockage, or one in a larger artery, damages more muscle.
CHD develops slowly over many years, so the risk factors act over a long time. This is one reason why they are hard to study.

The coronary arteries on the surface of the heart

Risk factors and the evidence for them

A risk factor is something linked with a higher chance of developing a disease. It does not mean that everyone with the factor will get the disease, or that people without it are safe.
Factors linked with CHD that can change: smoking (carbon monoxide reduces the oxygen the blood can carry, nicotine raises heart rate and blood pressure, and chemicals damage the artery lining); a diet high in saturated fat (raises LDL cholesterol in the blood); high salt intake and obesity (linked with high blood pressure); lack of exercise; diabetes.
Factors that cannot be changed: age (risk rises as people get older), sex (men are at higher risk at a younger age) and inheritance (a close relative who had CHD at a young age raises the risk).
Correlation is not causation. Two things can rise together without one causing the other. A third factor, a confounding variable, may cause both. For example, people who eat a lot of fried food may also exercise less and smoke more.
Scientists build the case in steps: large cohort studies that follow thousands of people over many years and compare rates of disease; a plausible mechanism (for example, how carbon monoxide affects haemoglobin); and controlled trials in which people are randomly put into groups.
Reading study data. Compare rates, not raw numbers: 120 cases among 4000 people (3.0%) is a higher rate than 90 cases among 6000 people (1.5%), even though the numbers of cases are close.

Exercise: how the heart and breathing respond

During exercise the muscle cells respire faster. They need more oxygen and glucose and must lose more carbon dioxide and heat. The heart and lungs respond together.
Heart: the heart rate rises and each beat pushes out more blood. The stroke volume is the volume of blood pumped by one ventricle in one beat. Cardiac output = heart rate x stroke volume. At rest, 75 beats per minute x 70 cm3 per beat = 5250 cm3 per minute (about 5.3 litres per minute).
Breathing: the rate and the depth of breathing both increase. The ventilation rate (volume of air breathed per minute) = breathing rate x tidal volume. The brain detects a rise in carbon dioxide in the blood and speeds up breathing.
If oxygen cannot reach the muscle cells fast enough, they also respire anaerobically, producing lactic acid. After exercise, extra oxygen is needed to break down the lactic acid. This is the oxygen debt, and it is why breathing and heart rate stay high for a while after exercise stops.
Training changes the body over weeks and months. The heart muscle becomes stronger, stroke volume at rest increases and the resting heart rate falls. After exercise, a fitter person's heart rate also returns to normal faster.
Heart rate can be measured by counting the pulse for a set time (for example, beats in 15 s x 4), by a heart-rate monitor, or by an ECG, which records the electrical activity of the heart. On an ECG trace, the time between two beats gives the rate: heart rate = 60 / time between beats in seconds.

Repaying the oxygen debt after hard exercise

Treating coronary heart disease

Statins are drugs that lower the level of LDL cholesterol in the blood, which slows the growth of atheroma. They are taken as tablets, usually for life. Some people have side effects such as muscle pain. Statins reduce the chance of a heart attack but do not remove a blockage that is already there.
A stent is a small mesh tube. A surgeon passes a thin tube through an artery to the narrowed coronary artery, inflates a small balloon to widen it, and leaves the stent in place to keep it open. It is less invasive than major surgery, but the artery can narrow again and the patient needs drugs to stop clots forming.
Coronary bypass surgery uses a blood vessel taken from elsewhere (for example the leg or the chest) to carry blood around a blocked section of a coronary artery. It is major surgery with a longer recovery, but it can treat several blockages.
A heart transplant replaces a failing heart with a healthy donor heart. There are far fewer donor hearts than patients who need them, and the patient must take immunosuppressant drugs for life so that the immune system does not reject the new heart. These drugs make infections more likely.
Doctors and patients weigh benefits, risks, costs and the person's wishes. Treatments are tested in trials before use. Prevention at the level of a population, such as lowering salt in food, can also reduce CHD.

Think like a scientist: how fast does your heart recover?

Question: does the length of time spent exercising change how long the heart rate takes to return to its resting rate? A group of healthy volunteers, who choose to take part, do step-ups on a low, stable step at a steady rhythm. Anyone who feels unwell stops at once.
The independent variable is the time spent exercising (for example 1, 2 and 3 minutes). The dependent variable is the recovery time: the time for the pulse to return to within 5 beats per minute of the resting pulse.
Control variables: the type and rhythm of the exercise, the step height, the volunteer (or volunteers of similar age), the room temperature, the rest period between trials, and the way the pulse is measured.
Reliability: repeat each time-length at least three times and calculate a mean. Identify any anomaly, for example a result far from the others, and say whether you would include it. Counting a pulse for 15 s and multiplying by 4 is less precise than using a heart-rate monitor.
Inquiry task 1: write a plan with a results table, including how you will decide when the pulse has recovered. Inquiry task 2: a student uses one volunteer, one trial per time-length, and concludes that exercise time causes slower recovery. Evaluate the conclusion and suggest three improvements.

Folien

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

REGISTRIEREN — GRATIS ANMELDEN

Übungsfragen

Gratis-Vorschau — 8 von 55 Fragen. Registriere dich, um alle zu sehen.

1.Which chamber of the heart pumps oxygenated blood to the whole body?
Easy
- AThe right ventricle
- BThe left atrium
- CThe left ventricle
- DThe right atrium
2.Which vessel carries oxygenated blood away from the heart to the body?
Easy
- AThe aorta
- BThe vena cava
- CThe pulmonary artery
- DThe pulmonary vein
3.Why is the wall of the left ventricle thicker than the wall of the right ventricle?
Easy
- AIt has to hold a much larger volume of blood than any other chamber can
- BIt pumps blood only a short distance, to the lungs
- CIt contains the valves that stop blood flowing backwards
- DIt must pump blood at a higher pressure to reach the whole body
4.Blood passes through the heart twice during one complete circuit of the body.
Easy
True or false?
5.Arteries carry blood away from the heart.
Easy
True or false?
6.Put the parts of the circulation in order, starting with blood returning from the body.
Easy
- Left atrium
- Right atrium
- Body tissues
- Lungs
- Left ventricle
- Right ventricle
7.Which feature is found in veins but not in arteries?
Medium
- AA thick muscular wall that resists high pressure
- BValves that stop the blood flowing backwards
- CA very narrow lumen with walls one cell thick
- DBlood moving in pulses with every heartbeat
8.Explain why the heart needs its own blood supply, even though it is full of blood. [2 marks]
Medium

Mehr Fragen

9.Which vessels supply the heart muscle with oxygen and glucose?
Easy
- AThe vena cava
- BThe coronary arteries
- CThe pulmonary veins
- DThe blood inside the atria
10.What is atheroma?
Easy
- AA blood clot that forms inside a vein in the leg and travels
- BA thickened heart valve that no longer closes properly
- CA hormone that raises the blood pressure of the whole body
- DA fatty deposit in the wall of an artery that narrows the lumen
11.What happens in a heart attack?
Easy
- AA coronary artery is blocked and part of the heart muscle loses its oxygen
- BThe heart valves open at the wrong time during each beat of the heart
- CThe pulmonary artery bursts and floods the lungs with blood quickly
- DThe heart muscle stops receiving signals that are sent from the brain
12.Complete the sentence.
Easy
A heart attack happens when a ____ artery becomes blocked.
13.Put these events in the order in which they lead to a heart attack.
Medium
- A blood clot forms and blocks the artery
- Fatty deposits build up in the wall of a coronary artery
- Part of the heart muscle is starved of oxygen
- The lumen of the artery becomes narrower
14.Explain how atheroma in a coronary artery can lead to a heart attack. [3 marks]
Medium
15.What is the name for chest pain caused when narrowed coronary arteries cannot supply enough oxygen during effort?
Easy
- AA stroke
- BArthritis
- CAngina
- DAsthma
16.Which of these are risk factors for coronary heart disease? (select all that apply)
Medium
- AHaving brown eyes
- BSmoking
- CA diet high in saturated fat
- DBeing right-handed
- EHigh blood pressure
17.Match each risk factor to the way it is linked with heart disease.
Easy
- Smoking
- High salt intake
- Saturated fat in the diet
- Lack of exercise
- Raises the level of LDL cholesterol
- Carbon monoxide reduces the oxygen carried by the blood
- Less strong heart muscle and a greater chance of obesity
- Raises the blood pressure
18.Which of these risk factors for CHD cannot be changed by a person?
Easy
- AThe amount of salt eaten in the diet
- BWhether or not a person smokes
- CThe amount of exercise taken each week
- DHaving a parent who developed CHD young
19.Everyone who has a risk factor for CHD will develop the disease.
Medium
True or false?
20.Carbon monoxide in cigarette smoke raises the risk of CHD. Which statement describes one way it does this?
Medium
- AIt dissolves the fatty deposits in the artery wall
- BIt combines with haemoglobin, so the blood carries less oxygen
- CIt slows the heart so that less blood is pumped
- DIt stops the liver making cholesterol
21.Complete the sentence.
Medium
A diet high in saturated fat raises the level of ____ cholesterol in the blood.
22.A survey finds that people who eat more fried food have more heart disease. What is the best reason for not concluding that fried food causes the disease?
Medium
- AFried food contains no fat that could ever be linked with the heart
- BSurveys can never be used to look at heart disease in any population
- COther factors, such as smoking or inactivity, may differ between the groups
- DHeart disease is only ever caused by genes inherited from parents
23.
A study in one town (invented numbers) compared smokers and non-smokers.
Group People CHD cases
Smokers 4000 120
Non-smokers 6000 90
Which statement is supported by the data?
Medium
- AThe rate of CHD in smokers is twice the rate in non-smokers
- BThe numbers of cases are almost equal, so smoking has no effect
- CSmoking proved to be the cause of all 120 cases among smokers
- DNon-smokers were twice as likely to get CHD as smokers were
24.In a study (invented numbers) of 2500 people with high blood cholesterol, 200 developed CHD over ten years. What percentage developed CHD?
Medium
25.Which piece of evidence gives the strongest support for the claim that a drug reduces heart attacks?
Hard
- AOne person who took the drug for many years and then lived to be ninety years old
- BA trial with random drug and placebo groups, where the drug group had fewer heart attacks
- CTwo graphs that both rose steadily over the same twenty years in one country
- DA survey asking a large sample of people what they believe that the drug does
26.A newspaper says that eating red meat causes heart disease. The report is based on a survey showing that people who ate more red meat had more heart disease. Evaluate the claim. [3 marks]
Hard
27.Why does the heart rate rise during exercise?
Easy
- AThe heart has to warm up the blood before it reaches the muscles
- BThe brain needs to make more lactic acid for the muscles
- CMuscles need more oxygen and glucose and must lose carbon dioxide
- DBlood must flow more slowly so that the muscles can absorb it
28.Which substance in the blood is detected by the brain and makes breathing faster during exercise?
Easy
- AOxygen carried by haemoglobin
- BNitrogen dissolved in the plasma
- CWater vapour that is breathed out
- DCarbon dioxide
29.Put these events in order to explain how breathing responds to exercise.
Medium
- The breathing rate and depth increase
- The carbon dioxide level in the blood rises
- The muscle cells respire faster
- The brain detects the rise in carbon dioxide
30.After running hard, a person keeps breathing fast for several minutes. What is the best explanation?
Medium
- AExtra oxygen is needed to break down lactic acid made in the muscles
- BThe lungs need extra time to build up a fresh supply of air
- CThe muscles must still store up carbon dioxide for the next hour
- DThe heart has stopped sending blood to the lungs for a while
31.Complete the sentence.
Easy
Lactic acid builds up in muscles because the cells respire ____ when the oxygen supply is too low.
32.How does regular training change the heart of a person at rest?
Medium
- AThe resting heart rate rises and the stroke volume falls
- BBoth the resting heart rate and the stroke volume fall
- CThe resting heart rate falls and the stroke volume rises
- DNeither the resting heart rate nor the stroke volume changes
33.Which of these happen during vigorous exercise? (select all that apply)
Medium
- AThe muscles need less oxygen than at rest
- BThe heart rate increases
- CThe stroke volume falls to nothing
- DThe breathing rate increases
- ELactic acid may be made in the muscles
34.Match each term to its meaning.
Medium
- Stroke volume
- Cardiac output
- Heart rate
- Ventilation rate
- The volume of air breathed in and out in one minute
- The volume of blood pumped by one ventricle in one minute
- The volume of blood pumped by one ventricle in one beat
- The number of heartbeats in one minute
35.Explain why the cardiac output increases during exercise. [3 marks]
Hard
36.A student counts a pulse for 15 seconds and finds 19 beats. Calculate the heart rate in beats per minute.
Easy
37.At rest, a person has a heart rate of 75 beats per minute and a stroke volume of 70 cm3. Calculate the cardiac output in litres per minute.
Easy
38.During exercise a person has a heart rate of 150 beats per minute and a stroke volume of 110 cm3. Calculate the cardiac output in litres per minute.
Medium
39.On an ECG trace (invented example), the time between two successive heartbeats is 0.75 seconds. Calculate the heart rate in beats per minute.
Easy
40.
A student's heart rate was measured after exercise (invented data). Her resting heart rate was 72 beats per minute.
Minute after exercise 0 1 2 3 4 5
Heart rate (beats per minute) 150 128 110 96 84 76
Recovery is defined as being within 5 beats per minute of the resting rate. At which minute had she recovered?
Medium
- AMinute 5
- BMinute 3
- CMinute 4
- DMinute 2
41.A student measured the pulse rate after exercise four times (invented data): 142, 145, 190 and 143 beats per minute. The value 190 is an anomaly because the pulse was counted for the wrong time. Calculate the mean after leaving it out, to the nearest whole number.
Hard
42.
Two students did the same exercise (invented data, one trial each).
Resting pulse Pulse straight after exercise Recovery time
Student A 72 150 6 min
Student B 64 138 3 min
Which conclusion is best supported?
Hard
- AStudent B is certainly fitter because the lowest numbers always mean fitter
- BStudent A has a healthier heart because the pulse reached a higher value
- CNothing can be said because the two students did not have the same pulse
- DStudent B may be fitter, but two single trials are too few to be sure
43.Breathing during hard exercise (invented data): the tidal volume is 1.8 litres and the breathing rate is 30 breaths per minute. Calculate the ventilation rate in litres per minute.
Hard
44.What is the main action of a statin?
Easy
- AIt widens a narrowed artery by leaving a small mesh tube in it
- BIt lowers the level of LDL cholesterol in the blood
- CIt replaces a diseased heart with a healthy donor heart
- DIt makes the heart beat faster and with greater force
45.What is a stent?
Easy
- AA drug that lowers the level of cholesterol in the blood
- BA small mesh tube that holds a narrowed artery open
- CA vessel taken from the leg and joined around a blockage
- DA machine that records the electrical signals of the heart
46.Match each treatment to its description.
Easy
- Statins
- Stent
- Bypass surgery
- Heart transplant
- A mesh tube that holds a narrowed artery open
- A failing heart is replaced by a donor heart
- Tablets that lower blood cholesterol
- A grafted blood vessel that carries blood around a blockage
47.Why must a person with a donor heart take immunosuppressant drugs?
Medium
- ATo make the donor heart grow to the right size
- BTo prevent the coronary arteries from developing atheroma
- CTo increase the number of white blood cells so that infections are rarer
- DTo stop the immune system attacking and rejecting the new heart
48.A heart transplant can save a life. Give one advantage and one disadvantage of this treatment. [2 marks]
Medium
49.There are fewer donor hearts available than there are patients who need a transplant.
Easy
True or false?
50.In a trial (invented numbers), 1000 people took a statin and 1000 took a placebo for five years. 40 people in the statin group and 60 in the placebo group had a heart attack. Calculate the relative reduction in heart attacks in the statin group, as a percentage of the placebo group's number.
Hard
51.Using the same trial (invented numbers: 40 heart attacks among 1000 on the statin and 60 among 1000 on the placebo), by how much did the percentage of people having a heart attack fall?
Hard
- ABy 2 percentage points
- BBy 20 percentage points
- CBy 33 percentage points
- DBy 40 percentage points
52.In an investigation into how exercise time affects recovery time of the pulse, which is the independent variable?
Medium
- AThe time for the pulse to recover
- BThe rhythm and the height of the step-ups
- CThe length of time spent exercising
- DThe temperature of the room
53.A student counts the pulse for 10 seconds and then multiplies by 6. Which change would most improve the reliability of the results?
Hard
- AUse a bigger step so that the exercise is much harder
- BRepeat each measurement and calculate the mean
- CExercise for longer in the last trial than in the first
- DRecord only the highest pulse rate that is measured each time
54.A student tests one volunteer once for each exercise time and concludes that longer exercise causes slower recovery. Evaluate the conclusion and suggest two improvements. [3 marks]
Hard
55.A heart-rate monitor is usually more precise than counting a pulse by hand for a short time.
Easy
True or false?

Lernnotizen

## Heart disease, exercise and circulation - The heart is a **double pump**: the right side sends blood to the lungs and the left side sends it to the body. The **coronary arteries** feed the heart muscle. - **Atheroma** narrows a coronary artery. A **clot** can block it and cause a **heart attack**. - **Risk factors** raise the chance of CHD: smoking, saturated fat, salt, inactivity, obesity, age, sex and inheritance. **Correlation is not causation**: look for confounding variables and compare **rates**. - Exercise raises **heart rate**, **stroke volume** and **breathing**. **Cardiac output = heart rate x stroke volume.** Anaerobic respiration makes **lactic acid** and creates an **oxygen debt**. - Training lowers resting heart rate and raises stroke volume. - Treatments: **statins**, **stents**, **bypass surgery** and **transplants**. Each has benefits, risks and costs. - A good investigation controls variables, repeats measurements, finds a mean and judges anomalies.

Coronary heart disease (CHD): Disease in which the coronary arteries are narrowed by atheroma, so the heart muscle gets too little blood.
Coronary arteries: The arteries that supply the heart muscle itself with oxygen and glucose.
Atheroma: A fatty deposit, containing cholesterol, in the wall of an artery.
Angina: Chest pain when the heart muscle gets too little oxygen during effort.
Heart attack: Death of part of the heart muscle after a coronary artery is blocked, often by a clot.
Risk factor: Something linked with a higher chance of developing a disease.
Correlation: A link between two variables that does not by itself show that one causes the other.
Confounding variable: A third factor that affects both variables and can create a misleading link.
LDL cholesterol: The type of cholesterol in the blood that builds up as atheroma.
Stroke volume: The volume of blood pumped by one ventricle in one beat.
Cardiac output: The volume of blood pumped by one ventricle in one minute: heart rate x stroke volume.
Oxygen debt: The extra oxygen needed after exercise to break down the lactic acid made by anaerobic respiration.
Statin: A drug that lowers the level of LDL cholesterol in the blood.
Stent: A small mesh tube that holds a narrowed artery open.
Immunosuppressant: A drug that reduces the activity of the immune system to prevent rejection of a transplant.

Karteikarten

What are the coronary arteries?

The arteries that supply the heart muscle with oxygen and glucose.

What is atheroma?

A fatty deposit, containing cholesterol, in an artery wall that narrows the lumen.

Describe how a heart attack happens.

A coronary artery is blocked, often by a clot on atheroma, so the muscle it supplies gets no oxygen and its cells die.

What is angina?

Chest pain when narrowed coronary arteries cannot supply enough oxygen during effort.

Give four changeable risk factors for CHD.

Smoking, a diet high in saturated fat or salt, lack of exercise and obesity (also diabetes).

Give three risk factors that cannot be changed.

Age, sex and inherited risk (family history).

Why is correlation not causation?

A third, confounding factor may cause both, or the link may be chance.

How does carbon monoxide in smoke increase CHD risk?

It binds to haemoglobin so the blood carries less oxygen, and the heart works harder.

Write the equation for cardiac output.

Cardiac output = heart rate x stroke volume.

How do you get heart rate from an ECG?

Heart rate in beats per minute = 60 / time between beats in seconds.

Why does breathing rate rise in exercise?

Rising carbon dioxide in the blood is detected by the brain, which speeds up breathing.

What is the oxygen debt?

Extra oxygen needed after exercise to break down lactic acid made by anaerobic respiration.

How does training change the heart?

Stronger heart muscle: higher stroke volume, lower resting heart rate.

What does a statin do?

Lowers LDL cholesterol in the blood, slowing the growth of atheroma.

How do a stent and a bypass differ?

A stent keeps a narrowed artery open; a bypass graft carries blood around a blockage.

Why are immunosuppressants given after a transplant?

To reduce rejection of the donor organ, though they raise the risk of infection.

How can you make heart-rate data more reliable?

Repeat measurements, calculate a mean, control variables and treat anomalies sensibly.

Unlock all 55 questions, flashcards & more

Erstelle ein Gratis-Konto, um alle Fragen, Folien, Karteikarten und Lernnotizen zu diesem Thema zu sehen.

REGISTRIEREN — GRATIS ANMELDEN

Altklausuren

Altklausuren-Übungen für dieses Thema kommen bald.

Bald verfügbar

Group	People	CHD cases
Smokers	4000	120
Non-smokers	6000	90

	Resting pulse	Pulse straight after exercise	Recovery time
Student A	72	150	6 min
Student B	64	138	3 min