unit 1 – the human body in motion · unit 1 – the human body in motion area of study 2 - how...

Unit 1 – The Human Body in Motion

AREA OF STUDY 2 - HOW DOES THE CARDIORESPIRATORY SYSTEM FUNCTION AT REST AND DURING PHYSICAL ACTIVITY?

The Cardiovascular System



The cardiovascular system consists of:- Heart Blood vessels Blood Pulmonary circuit (blood flow between the

heart and lungs) Systemic circuit (blood flow between the

heart and the body)


The functions of the cardiovascular system are to:- circulate blood bring O2 , water & nutrients to the cells. take CO2 & other wastes away from the cells. maintain body temperature and hydration. fight disease blood clotting

The Heart

Right Atrium

Right Ventricle Left Ventricle

Left Atrium

Pulmonary Vein

Heart Muscle

Pulmonary ArteryAorta

Inferior Vena Cava

Superior Vena Cava

The Heart

The heart has a number of heart valves that control the direction of blood flow through the heart.

Valve

The Heart

Blood flow through the heart:- 1. Oxygenated blood arrives from the lungs through the

pulmonary veins and enters the left atrium. 2. Oxygenated blood passes into the left ventricle. 3. A powerful contraction of the heart muscle surrounding

the the left ventricle pumps oxygenated blood out through the aorta to the body.

4. Deoxygenated blood comes back from the body and enters the right atrium through the vena cava.

5. Deoxygenated blood passes into the right ventricle. 6. Deoxygenated blood returns to the lungs via the

pulmonary arteries.

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2

3

4

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The Blood vessels are intricate networks of hollow tubes that transport blood throughout the entire body.

There are three major types of blood vessels: ARTERIES - carry blood away from the heart CAPILLARIES – allow the exchange of gases,

nutrients & wastes between the blood and the tissues.

VEINS – carry blood back to the heart.

The Blood Vessels

Arteries

Arterioles

CapillariesExchange between blood and cells

Veins

Venules

The Blood Vessels

THE BLOOD The blood has a number of functions:- Transport of gases, nutrients, wastes. Fighting infection. Regulation of temperature and

hydration.

The volume of blood contained in the body is: Adult males 5 – 6 litres Adult females 4 – 5 litres

The Blood

THE BLOOD Within the blood:- 55% is plasma - a yellowy liquid

containing water ( 90% ) , wastes & hormones.

45% of the blood volume is the blood cells.

Blood cells include:- RED BLOOD CELLS – contain haemoglobin

which carries the oxygen WHITE BLOOD CELLS – fight infection PLATELETS – responsible for blood clotting

The Blood

Blood pressure is the reason why blood circulates. Blood will always flow from an area of high pressure to

one of low pressure. SYSTOLIC blood pressure is the highest pressure and is

the pressure on the arteries as the left ventricle contracts. ( 120 mmhg at rest )

DIASTOLIC blood pressure is the lowest pressure and is the pressure on the arteries as the left ventricle relaxes. ( 80 mmhg at rest )

Blood Pressure

Circulation of Blood – Heart Rate

Heart Rate – the number of heartbeats per minute (bpm).

Resting heart rate is the heart pumping the lowest amount of blood you need because you’re not exercising.

Resting heart rate is normally between 60 bpm and 100 bpm.

Circulation of Blood –Stroke Volume and Cardiac Output

Stroke volume (SV): the amount of blood ejected by the left ventricle in one contraction.

Stoke volume at rest is around 75ml/beat and can increase to 105ml/beat following endurance training.

Cardiac output (Q): the amount of blood the heart pumps through the circulatory system in a minute.

Stroke volume and the heart rate determine the cardiac output:- Cardiac output (Q) = Stroke Volume (SV) X

Heart Rate (HR) At rest cardiac output is between 5 and 6

litres of blood per minute.

Thermoregulation

Thermoregulation is a process that allows your body to maintain its core internal temperature.

If the body needs to cool down, these mechanisms include: Sweating: sweat glands release sweat, which cools

as it evaporates.

Vasodilatation: blood vessels under the skin get wider increasing blood flow to skin where it is cooler —allowing body to release heat through heat radiation.

If the body needs to warm up, these mechanisms include: Vasoconstriction: blood vessels under the skin

become narrower decreasing blood flow to skin, retaining heat near the warm inner body.

Thermogenesis: body’s muscles, organs, and brain produce heat in a variety of ways. E.g. muscles can produce heat by shivering.

Hypothermia - Symptoms

Hypothermia is a potentially dangerous drop in temperature usually caused by prolonged exposure to cold temperatures.

Symptoms of hypothermia include:- Shivering, which may stop as hypothermia progresses.

Slow, shallow breathing.

Confusion and memory loss.

Drowsiness or exhaustion.

Slurred or mumbled speech.

Loss of coordination, fumbling hands, stumbling steps.

A slow, weak pulse.

In severe hypothermia, a person may be unconscious without obvious signs of breathing or a pulse.

Hypothermia - Treatment

Rapid treatment is vital as Hypothermia is a potentially life-threatening condition.

The following steps should be taken in the treatment of hypothermia. Remove any wet clothes, hats, gloves, shoes, and

socks. Protect the person against wind, drafts, and further heat

loss with warm, dry clothes and blankets. Move gently to a warm, dry shelter as soon as possible. Begin rewarming the person with extra clothing and

warm blankets. Offer warm liquids, but avoid alcohol and caffeine. If the hypothermic person is unconscious, or has no

pulse or signs of breathing begin CPR (cardiopulmonary resuscitation) immediately.

Hyperthermia - Causes

Hyperthermia is elevated body temperature due to failed thermoregulation that occurs when the body produces or absorbs more heat than it dissipates.

Factors that contribute to the development of hyperthermia include:- Participating in vigorous activity in a hot humid

environment.

Dehydration from not drinking enough water.

Wearing bulky or heavy clothing in the heat.

Being overweight, which causes the body to generate more heat and reduces the body's ability to cool down.

Being unaccustomed to the heat, such as moving from a cooler climate to a warmer climate.

Hyperthermia –Symptoms and Treatment

Symptoms of hyperthermia include:- abdominal cramps muscle cramps nausea vomiting headache dizziness heavy sweat or a lack of sweat

If ignored, dehydration can lead to:- Heat exhaustion – the body is failing to cool itself. Heat stroke – the body stops sweating and core

temperature rises – this can be fatal.

Hyperthermia –Symptoms and Treatment

Strategies to prevent onset of hyperthermia include:- Drink lots of water throughout the day.

Stay indoors in an air-conditioned area whenever you feel too warm.

Wear lightweight, light-colored clothing, preferably with a loose-weave material that lets air get to your skin.

Avoid strenuous activity in the hottest part of the day (between 10 a.m. and 4 p.m.).

Circulation of Blood –Arteriovenous Oxygen Difference (aVO2 )

Arteriovenous Oxygen Difference (aVO2) is the difference between the oxygen content of arterial blood and mixed venous blood.

Expressed as millilitres per 100mL of blood –represents the extent to which oxygen is removed from the blood as it passes through the body.

aVO2 Rest

Oxygen concentration in arterial blood 20mL/100mL

Oxygen concentration in venous blood 16mL/100mL

aVO2 = 4mL/100mLaVO2 Exercise

Oxygen concentration in arterial blood 20mL/100mL

Oxygen concentration in venous blood 4mL/100mL

a-V02 = 16mL/100mL

Redistribution of Blood Flow During Exercise

As you exercise, the blood vessels in your muscles dilate (vasodilation) and the blood flow is greater.

Increased blood flow delivers more oxygenated blood to the working muscle.

When you begin to exercise, a nervous stimulation causes blood vessels transporting blood to organs such as the kidneys and stomach to constrict (vasoconstriction) thus reducing blood flow to tissues.

Because the rest of the body gets the message to constrict the blood vessels and the muscles dilate their blood vessels, blood flow from nonessential organs (for example, stomach, intestines and kidney) is diverted to working muscle helping increase the delivery of oxygenated blood.

Percentage of Blood Flow at Rest (5000ml)

MusclesHeartSkinBrainLiverKidneys

Percentage of Blood Flow Exercise (25000ml)

MuscleSkinLiverOtherHeartKidneysBrain

Acute cardiovascular responses to exercise

Cardiovascular Response Increase Decrease Unchanged

Heart Rate (BPM)

Stoke Volume (SV)

Cardiac Output (Q)

Systolic Blood Pressure

Diastolic Blood Pressure

Arteriovenous Difference (a-VO2)

Blood Plasma

Blood flow to muscles

Blood flow to lungs

Blow flow to organs

Cardiovascular Health


Cardiovascular Disease

Cardiovascular diseases are diseases of the heart and blood vessels.

CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause.

Cardiovascular disease (CVD) is a major cause of death in Australia.

One in six Australians are affected by cardiovascular disease.

Most cardiovascular diseases can be prevented by addressing behavioural risk factors such as tobacco use, unhealthy diet and obesity, physical inactivity and harmful use of alcohol.

Cardiovascular Disease

A person with cardiovascular disease will have one or more of the following conditions :

Coronary heart disease

Angina pectoris

Atherosclerosis

Arteriosclerosis

Stroke

Peripheral vascular disease

Hypertension

Cardiovascular Disease –Risk Factors

Risk factors that can’t be altered:- Age Gender Family history

Risk factors that can be altered:- Physical inactivity Overweight High blood pressure High blood fat levels High blood cholesterol levels High stress levels Diabetes Smoking

Non Modifiable Risk Factors

Age CVD becomes increasingly common with advancing age. As a person gets

older, the heart undergoes subtle changes.

Gender A man is at greater risk of heart disease than a pre-menopausal woman. Once

past the menopause, a woman’s risk is similar to a man’s. Risk of stroke, however, is similar for men and women.

Family history A family’s history of CVD indicates a person’s risk. If a first-degree blood relative

has had coronary heart disease or stroke before the age of 55 years (for a male relative) or 65 years (for a female relative), the risk increases.

Modifiable Risk Factors

Physical Inactivity Physical activity protects you by regulating your weight and improving your

body’s use of insulin.

Being active is beneficial for your blood pressure, blood lipid levels, blood glucose levels, blood clotting factors and the health of your blood vessels.

Obesity If you are overweight you may develop hypertension, diabetes and

atherosclerosis.

Being obese affects your blood pressure, your blood lipid levels and interferes with your ability to use insulin effectively.


High Blood Pressure Hypertension stresses your body’s blood vessels, causing them to clog or

weaken.

Hypertension can lead to atherosclerosis and narrowing of the blood vessels making them more likely to block from blood clots or bits of fatty material breaking off from the lining of the blood vessel wall.

Damage to the arteries can also create weak places that rupture easily.

High Blood Cholesterol High levels of cholesterol speeds up the development of atherosclerosis.


High Stress Levels Studies show that acute stress triggers reduced blood flow to the heart,

promotes irregular heart beat and increases the likelihood of your blood clotting.

Diabetes Uncontrolled diabetes causes damage to your body’s blood vessels making

them more prone to damage from atherosclerosis and hypertension.

People with diabetes develop atherosclerosis at a younger age and more severely than people without diabetes.


Smoking Smoking damages the lining of the blood vessels, increases fatty deposits in the

arteries, increases clotting, raises low-density lipoprotein cholesterol, reduces high-density lipoprotein and promotes coronary artery spasm.

Coronary Heart Disease

Coronary heart disease (CHD) is a disease in which a waxy substance called plaque builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart muscle.

CHD can lead to:- angina (chest pain or discomfort)

heart attack (complete obstruction of blood flow)

arrhythmias (irregular heartbeats)

Angina Pectoris

Angina pectoris is chest pain or discomfort due to coronary heart disease. It occurs when the heart muscle doesn't get as much blood as it needs. This usually happens because one or more of the heart's arteries is narrowed or blocked.

Angina usually causes uncomfortable pressure, fullness, squeezing or pain in the center of the chest.

Atherosclerosis

When plaque builds up in the arteries, the condition is called atherosclerosis.

Over time, plaque hardens which narrows the coronary arteries and reduces the flow of oxygen-rich blood to the heart.

If plaque ruptures a blood clot can form, which if large enough, can mostly or completely block blood flow through a coronary artery. Ruptured plaque also hardens and narrows the coronary arteries.

Arteriosclerosis

Arteriosclerosis is the hardening and thickening of the walls of the arteries.

Arteriosclerosis can occur because of:-

fatty deposits on the inner lining of arteries (atherosclerosis)

calcification of the wall of the arteries

thickening of the muscular wall of the arteries from chronically elevated blood pressure

Stroke

A stroke occurs when the blood supply to part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and nutrients.

The blockage of blood flow or rupture of an artery to the brain results in a lack of oxygen supply and a sudden death of brain cells.

High Cholesterol

Cholesterol is a type of fat (lipid) in your blood.

Cholesterol is produced in the liver and is also found in some foods we eat.

It aids in making cell membranes, hormones, vitamin D and bile.

If you have too much cholesterol (from the types of foods we eat) , it starts to build up in your arteries leading to cardiovascular disease.

Peripheral Vascular Disease

Peripheral vascular disease (PVD) is a blood circulation disorder that causes the blood vessels outside of your heart and brain to narrow, block, or spasm.

This can happen in your arteries or veins.

It reduces oxygen supply around the body.

Hypertension

Hypertension is defined as having a blood pressure higher than 140 mmHg over 90 mmHg.

Uncontrolled high blood pressure can lead to:- artery damage and narrowing

coronary artery disease

enlarged left heart

heart failure

stroke

kidney failure

Role of Physical Activity in Controlling Risk Factors

Regular physical activity makes you less likely to have a heart attack or develop heart disease. It also helps control other heart disease risk factors like high blood pressure, high cholesterol, and being overweight.

Risk Factor Role of ExerciseObesity Obesity results from energy imbalance: too many kilojoules in, too few kilojoules burned.

Keeping active can help people stay at a healthy weight or lose weight.High blood pressure Exercise intervention studies have consistently shown that moderate intensity aerobic

exercise lowers blood pressure.High blood cholesterol Exercise raises the levels of heart-protecting HDL cholesterol and drops dangerous

triglyceride levels,

High stress levels Exercise helps to increase the production of your brain's feel-good neurotransmitters, called endorphins.

Diabetes When you are active, your cells become increasingly sensitive to insulin removing glucose more efficiently, thus lowering blood glucose.

Revision Questions

When the heart contracts it pumps blood into the:

A/ arteries.

B/ veins.

C/ capillaries.

D/ arterioles.

After leaving the heart the blood will take the following pathway:

A/ veins - venules - capillaries - arterioles -arteries.

B/ arterioles - arteries - capillaries - veins - venules.

C/ arteries - veins - capillaries - venules -arterioles.

D/ arteries - arterioles - capillaries - venules - veins.

Arterio - venous oxygen difference (a-Vo2 diff) is greatest at:

A/ maximal exercise

B/ sub maximal exercise

C/ rest

D/ none of the above – it remains constant

In which of the following does blood have the lowest concentration of oxygen ?

A/ coronary artery

B/ inferior vena cava

C/ pulmonary vein

D/ carotid artery

Revision Questions

Explain the function of the heart muscle.

Receives oxygenated blood from the lungs pumps blood out to the bodyreceives deoxygenated blood from bodypumps blood back to lungs.

List four functions of the cardiovascular system.

Circulates blood, takes carbon-dioxide & wastes away from cells, fights disease, transports oxygen & nutrients to the cells maintains body temperature.

What is the function of haemoglobin ?

Carries oxygen to working muscles and vital organs.

Describe the function of the following:Arteries

Carry blood away from heart.

Capillaries

Allow transfer of oxygen and carbon-dioxide.

Veins

Bring blood back to heart.

unit 1 – the human body in motion · unit 1 – the human body in motion area of study 2 - how...

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