Muscle Contractions & Cardiorespiratory

Year 11 HMS: Mind and body in motion. I want them to do an investigative lesson on muscle contractions.

I want them to plan to film them selves comepleteing a sport action/skill and identify the muscle contractions and the interrelationship of the biomechanical principles.

main content points:

• types of muscle contractions
• muscle relationship

Outline the interrelationship between biomechanical principles and the muscles, bones and joints of the body for safe movement. Including: how biomechanical principles are applied to human movement, including motion, balance and stability, fluid mechanics and force How biomechanical principles can be used to enhance safe movements How biomechanical principles can be used to increase movement efficiency

Activity 2: Structure and function of the cardiorespiratory system. I have copy and pasted some work from a booklet on this topic

Explain the interrelationship between the respiratory and circulatory systems and movement Including: structure and function pulmonary and systemic blood circulation and gaseous exchange factors that impact on the efficiency of the cardiovascular system

Demonstrate and analyse how the systems of the body work together in a variety of movements

KIQ1- How do the systems of the body influence and respond to movement? The Structure and Function of the Cardiorespiratory System

Syllabus Content Explain the interrelationship between the respiratory and circulatory systems and movement.

NESA Glossary of Key Words

Explain: Relate cause and effect; make the relationships between things evident; provide why and/or how.

This is a step beyond ‘describe’ – you must give reasons or mechanisms. If a question says, “Explain how the cardiorespiratory system supports movement,” you should mention both the circulatory and respiratory systems and clarify how one affects the other – essentially answering “why does this result in that?”. Words like because, therefore, thus are often used in an explanation.

The Respiratory System The respiratory system refers to the set of organs that allows a person to breath (air in and out). This includes the: nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli. These organs combine to allow for the exchange of oxygen and carbon-dioxide between the air in your lungs and your blood. It is this exchange that allows not only for movement to occur at various intensities, but also to sustain life. The respiratory system is clearly connected with the circulatory system and should be considered together. Together they are often called the cardiorespiratory or cardiovascular system. This is because both systems on their own are insufficient to create movement or maintain life.

Questions:

1. What is respiration? What is the difference between inspiration and expiration?

2. Use the diagram to explain gas exchange.

Practical application: Measure how many breaths you take each minute after each activity.

Number of breaths: Resting 3 v 3 basketball Run to the top of the Silo and back down.

Why did the respiratory rate increase?

Which extra muscles (beyond diaphragm and intercostals) did you utilise to breathe deeper?

How does your breathing rate and depth compare between activities?

Circulatory System

Components of blood

The circulatory system is a transport system that transports food, oxygen and nutrients around the body. It also helps remove waste products from the body.

Use the textbook to name the three parts of the circulatory system:

B___________________ V____________________ A_________________ V__________ C_________________ H_______________________ B__________________________

Watch the following video to answer the next TWO activities.

Name the three main functions of blood:

Component Function Plasma

Red blood cells

White blood cells

Platelets

Structure and Function of the Heart The heart is a muscular pump that contracts rhythmically, providing the force to keep the blood circulating throughout the body. It is slightly larger than a clenched fist and is the shape of a large pear. The heart lies in the chest cavity between the lungs and above the diaphragm, and is protected by the ribs and sternum.

The heart beats an average of 70 times per minute at rest. This amounts to more than 100 000 beats per day. In one day the heart pumps approximately 12 000 litres of blood, which is enough to fill a small road tanker.

A muscle wall divides the heart into a right and left side. Each side consists of two chambers: • atrium — the upper, thin-walled chambers that receive blood coming back to the heart • ventricles — the lower, thick-walled chambers that pump blood from the heart to the body.

A system of four one-way valves allows blood to flow in only one direction through the heart; that is, from the atria to the ventricles (the atrioventricular valves) and from the ventricles into the main arteries taking blood away from the heart (the arterial valves).

Action of the heart The heart is able to receive blood from the veins and pump it to the lungs and the body through a rhythmic contraction and relaxation process called the cardiac cycle. The cardiac cycle consists of the: diastole (relaxation or filling) phase. The muscles of both the atria and ventricles relax. Blood returning from the lungs and all parts of the body flows in to fill both the atria and ventricles in preparation for systole (contraction). systole (contraction or pumping) phase. The atria contract first to further fill the ventricles. The ventricles then contract and push blood under pressure to the lungs and all parts of the body. As they contract, the rising pressure in the ventricles closes the atrioventricular valves (between the atrium and the ventricle) and opens the valves in the arteries leaving the heart (the aorta and the pulmonary artery).

Copy the following diagram into Google Slides, Paint etc to enable you to edit. Label the following diagram. Indicate where the blood is oxygenated and deoxygenated.

Complete the table indicating the function of each part.

Oxygenated / Deoxygenated Function Aorta Oxygenated Distributes blood from the left ventricle to the rest of the body. Inferior vena cava Left atrium Left ventricle Pulmonary artery Pulmonary vein

Right atrium

Right ventricle

Superior vena cava

Structure and Function of the Arteries, Capillaries and Veins

Using the diagram, and your textbook, define pulmonary circulation. (Hint: make sure you do it in your own words)

Using the diagram, and your textbook, define systemic circulation. (Hint: make sure you do it in your own words)

Factors that impact the cardiovascular system Cardiovascular efficiency is the most important factor that determines overall aerobic fitness. High cardiorespiratory efficiency also significantly reduces the risk of cardiovascular disease. There are a number of factors that can be both advantageous or detrimental to the efficiency of the cardiovascular system. Some of the major factors include: altitude haemoglobin levels vascular disease.

Altitude Altitude (height above sea level) can have either a positive or negative impact on the efficiency with which the cardiovascular system operates. At an altitude of 1500 m or higher above sea level, the air is thinner and so the lungs struggle to extract sufficient amounts of oxygen to deliver to the muscles and tissues. As altitude increases, oxygen in the atmosphere further decreases. If a person is not used to these conditions, they can get a condition known as acute hypoxia, which is characterised by decreased oxygen in the blood, leaving insufficient levels for normal bodily function. Acute hypoxia, will have a detrimental impact on the ability of the cardiovascular systems to function efficiently. Effects range from mild, such as shortness of breath and rapid breathing, through to severe, such as coma and even death.

However, gradual acclimatisation can have a positive impact on the functioning of the cardiovascular system. This is because hypoxia produced at altitude stimulates physiological adaptations that improve cardiovascular functioning both at rest and during exercise. Due to the air being thinner at altitude, less oxygen is inhaled with each breath; to counter that, the body produces more red blood cells and hence haemoglobin. If acclimatisation at altitude is done gradually and safely, improvements in endurance performances at sea level are well documented, along with improvements in cardiovascular efficiency. Many endurance athletes and sports teams now include altitude training in their programs, either by training in a high-altitude environment, gradually increasing the altitude usually over a few weeks, or in a prefabricated environment such as a training room that simulates the conditions experienced at altitude and hence brings about the positive adaptations.

Read the case study ‘Running on thin air’ to clearly understand the impact that altitude can have on athletic performance and answer the questions that follow.

Running on thin air The 1968 Mexico City Olympic Games have had sport scientists’ minds racing for decades. It was an Olympics where some records were smashed beyond comprehension, and others were completely untouchable. Why? The answer is up in the air. Literally. Mexico City sits 2240 metres above sea level where the high altitude and thin air can wreak havoc on the human body. For Professor Chris Gore, Head of Physiology at the Australian Institute of Sport (AIS), understanding the effects of altitude has become a fixation. ‘It’s been my passion for 15 years. I think it’s fascinating and I’m always trying to find new ways to help athletes and coaches use altitude training more effectively.’ So what happens to the air at high altitudes to affect our bodies so much? This is due to the effects of gravity (which keeps air close to the ground) and heat (as you get closer to the sun) which cause molecules to bounce off one other and expand. So as you reach higher altitudes, the air expands. Any given volume of air is comprised of 79 per cent nitrogen, 20.9 per cent oxygen and 0.1 per cent other gases such as argon and krypton. But as you get higher and higher above sea level, the pressure of the atmosphere decreases. While the composition of the air stays the same, the expansion means that the air is ‘thinner’ — so in essence, at higher altitudes you inhale less oxygen and nitrogen molecules than you would at sea level. This drives a cascade of physiological responses in the human body. To begin with, your body increases its heart rate and respiratory rate to increase the amount of oxygen taken in and circulated around the body. So for example, while an athlete might normally run with a heart rate of 150 beats per minute, at high altitude it might increase to 165. Then the body begins to respond and adapt to the altitude (a process called acclimatisation). More than 200 genes are turned on in response to altitude, and one that is most commonly thought of is that which induces the creation of more red blood cells thereby increasing the amount of haemoglobin in the blood. Haemoglobin is the protein that binds oxygen molecules to red blood cells. The more haemoglobin in the blood cells, the more efficient the cells will be at carrying oxygen around the body. This means that even though less oxygen is taken into the lungs, it is more easily transported to the muscles. Finally, as you breathe faster and faster, the amount of carbon dioxide in the blood is reduced, which leads to the blood becoming less acidic. To counter this, the kidneys release blood bicarbonate to try to balance the PH level. For athletes, this is a big advantage since blood bicarbonate is the primary source of protection for muscles against lactic acid — the waste that builds up during exercise and leaves muscles feeling stiff and sore. While most of the scientific world has focused on the benefits of more haemoglobin following altitude training, Professor Gore and his colleagues have looked at the range of other effects. His work has proven that muscle buffering capacity is improved and that blood lactate levels during exercise are lowered. Additionally, the AIS scientists have found that athletes become more efficient after altitude exposure. Just like high altitude natives, athletes are able to use less oxygen to do the same amount of work after they have been at simulated altitude. The down side, however, is that many of these physiological responses do not occur straight away. It can take days, even weeks for the human body to fully adapt to the effects of altitude and for athletes to reap the benefits of better muscle protection and more efficient oxygen transportation. Scientists have determined that at high altitudes of 2400 meters plus, we inhale approximately three quarters of the amount of oxygen molecules that we would at sea level. This decreases as you go higher. As a reference, on the summit of Mount Everest (8848 m above sea level) we inhale only a third of the amount of oxygen we would at sea level, which is not enough to sustain human life. Altitude training at the AIS To simulate this low atmospheric pressure, enabling athletes to get the benefits of altitude training without having to travel to high altitude areas, scientists at the Australian Institute of Sport have developed an ‘altitude house’. This house, comprised of 12 beds, bathroom, kitchen and a lounge, simulates what it would be like to live at high altitude. The AIS recreate the low pressure atmosphere of 2500 metres by changing the composition of the air within the house to approximately 85 per cent nitrogen and 15 per cent oxygen. The air is not thinner, but the presence of less oxygen is physiologically equivalent to being at altitude. Athletes from endurance sports like cycling, rowing, race walking and swimming live in the house for 3–4 weeks at a time, a couple of times a year. At the same time, they maintain their standard training regime in the normal atmosphere in Canberra, which is 600 metres above sea level. According to Professor Gore, this ‘live high, train low’ program enables athletes to reap the benefits of high altitude living, while still enabling them to train with the same intensity and frequency. ‘Australia is at a disadvantage to other countries because we don’t really have big mountains for our athletes to live or train on, so the altitude house allows us to simulate what other countries have already,’ Professor Gore said. ‘And this way we get similar benefits from the altitude house that we would get from natural altitude by flying the athletes to train in say Europe, but without having to sacrifice their access to their physios, doctors, nutritionists, friends and family.’ Some athletes use the house as preparation for events where they will be competing at high altitudes. Mainly however, coaches are using the ‘altitude’ house as a way to improve performance at sea-level events. ‘By living in the house for 12 hours or so a day, the athlete’s red blood cell counts increase, their haemoglobin increases. As well, their muscle buffering capacity, ability to handle lactic acid and their efficiency also improves. They can then use these factors to their advantage in training and competitions. ‘Overall, we’re talking about a 1–2 per cent increase in performance, which mightn’t sound like much, but can be the difference between a medal and failing to qualify,’ Professor Gore said. But the effects don’t last forever. For example, Professor Gore quotes a study where Kenyan runners who lived and trained in high altitude all their lives were taken to a low-altitude region of Germany to train. After six weeks the runners had lost 5 per cent of their haemoglobin showing a relatively fast de-adaptation. ‘The verdict is still out, but we’re looking at benefits lasting for between 2–4 weeks for sea-level athletes who return to normal sea-level training.’ For Professor Gore, one of the most interesting things about altitude is its ability to both hinder and help athletes, depending on their event. ‘In cycling for example, the thin air means there is less drag, and in short stints in particular, athletes’ ability to absorb oxygen is not badly affected. This is true of almost all explosive events, including sprints, long jump and triple jump. ‘But for endurance events, like the ones our altitude training athletes compete in, kayaking, rowing and race walking, they are hit hard by the lack of oxygen and the lack of air resistance means little,’ Professor Gore concluded.

Source: Australia’s Chief Scientist 2012, https://www.chiefscientist.gov.au/2011/05/running-on-thin-air/

What is meant by ‘air is thinner’ at higher altitudes?

Describe how the body acclimatises to air at high altitudes.

How does Australia’s ‘altitude house’ function to improve acclimatisation?

How long do the benefits of altitude training last?

Explain how altitude training impacts the efficiency of the cardiovascular system.

Haemoglobin Levels Haemoglobin is the oxygen-carrying component of the blood. Higher levels of haemoglobin increase the amount of oxygen that can be delivered to the muscles and organs both at rest and during exercise. This is a significant advantage for athletes. However, conditions such as anaemia and iron deficiency reduce the amount of haemoglobin in the blood and reduce the body’s ability to deliver oxygen both at rest and during exercise. Higher haemoglobin levels in the blood mean that more oxygen can be absorbed from the lungs and carried to the muscles and tissues, which has a positive impact on the efficiency of the cardiovascular system and overall health. Higher levels of haemoglobin in the blood also benefits endurance athletes by allowing them to exercise at greater intensities for longer periods of time before fatiguing. It is therefore a desirable physiological adaptation that many athletes seek to obtain.

Low levels of haemoglobin can have a negative impact on the cardiovascular system by reducing the amount of oxygen being delivered around the body. When a person has low levels of haemoglobin, their cardiovascular system does not work efficiently because the heart has to work harder to ensure that the muscles and organs get the oxygen they require both at rest and during exercise. During heavy exercise, lower haemoglobin levels in the blood means inadequate oxygen is being delivered to meet the body’s needs and the person can become exhausted and feel unwell. Iron deficiency and anaemia reduce the levels of haemoglobin in the blood and therefore have a negative impact on the ability of the cardiovascular system to work effectively. Vascular disease Vascular disease is caused by a number of conditions that affect the blood vessels of the circulatory system. It has a negative impact on the ability of the cardiovascular system to function because the blood vessels cannot perform their role effectively. This leads to insufficient oxygen and nutrient delivery as well as poor waste removal from the body. The main cause of vascular disease is atherosclerosis, which is the build-up of fatty and/or fibrous material, known as plaque, on the interior walls of arteries. The build-up of these deposits causes the arteries to become narrow. This hinders blood flow to the body’s tissues, increases blood pressure and decreases the elasticity of the artery walls. Figure 7.47 shows the impact that atherosclerosis has on an artery’s structure; it can cause a complete blockage to occur. Depending on the artery affected, this can cause heart attacks, stroke or peripheral vascular disease. Accumulation of plaque happens over a long period of time and can be symptomless until atherosclerosis is advanced and the blood flow to the organs and muscles is compromised due to the narrowing of the artery.

Once this occurs, individuals will begin to experience the following symptoms: shortness of breath and fatigue due to insufficient supply of oxygenated blood angina, which is a medical term used to describe the chest pain that occurs when the heart has an insufficient supply of oxygenated blood blood clots due to plaque rapturing in the wall of the artery and causing platelets to form clots at the site of the rupture. This forms blockages in the artery or, if the clot enters the bloodstream, it can cause further serious health issues.

When performing exercise, the heart requires an increased supply of oxygenated blood. The presence of atherosclerosis in the arteries reduces the much-needed supply of blood, depriving the working muscles of the oxygen they require and hindering the functioning of the heart and hence performance in aerobic activities. Exercise is one of the main protective factors that reduces the risk of a person developing atherosclerosis and subsequent vascular disease.