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Science 30 – Unit A – Living Systems Respond to Their Environment

Science 30

Unit A – Living Systems Respond to Their Environment

General Outcome 1: Students will analyze how the human circulatory system facilitates

interaction between blood cells and the external environment and investigate

cardiovascular health.

Specific Outcome 1.1: Describe the principal structures and associated blood

vessels of the heart.

Specific Outcome 1.2: Describe the rhythmic contraction of the heart and its

function in the general circulation of blood through pulmonary and systemic

pathways.

Specific Outcome 1.3: Describe the structure and function of the blood vessels

and the flow of blood through arteries, arterioles, venules, veins and capillaries.

Specific Outcome 1.4: Describe the main components of blood and their role in

the transportation of substances, blood clotting, the defence against pathogens

and the distribution of thermal energy.

Textbook reference pages: p. 6 – 41 in Science 30

CIRCULATORY SYSTEM (CARDIOVASCULAR SYSTEM)

The circulatory system is the body’s internal transportation system that includes the

heart, the blood vessels and the blood.

The circulatory system has 4 main functions:

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Science 30 – Unit A – Living Systems Respond to Their Environment

1.1 THE HEART

About the size of your fist

Located in the centre of your chest (behind the sternum

bone)

Composed of two parallel pumps

Separated by the septum (blood from either side never

mixes)

Right side pumps blood to the lungs

Left side pumps blood to the body

Each pump is composed of two chambers

o An atrium (welcomes blood to the heart)

o A ventricle (pumps blood out of the heart)

Valves connect the atria to the ventricles

Valves allow blood to flow down only (from atrium to

ventricle)

I am an amazing

muscle that beats

about 70 times

every minute.

CORONARY ARTERIES – the vessels that

supply the heart muscle with oxygen-rich

blood.

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Science 30 – Unit A – Living Systems Respond to Their Environment

HEART ANATOMY

SEPTUM – the thick wall of muscle that divides the left and the right sides of the heart

ATRIUM – the smaller upper chamber that receives blood returning to the heart

VENTRICLE – the larger V-shaped bottom chamber that pumps blood from the heart

HEART VALVES – thin flaps of tissue in the heart that open and close to ensure the proper

direction for blood flow

2007 Alberta Education

Name: __________________________________

Science 30 – Unit A – Living Systems Respond to Their Environment

RIGHT

VENTRICLE

• Receives oxygen poor blood from the contraction

of the right atrium causing the valve to open

PULMONARY

ARTERY

• Receives oxygen-poor blood from the contraction of the right

ventricle causing the valve to open sending the blood to the

lungs to be oxygenated

PULMONARY

VEINS

• Receives oxygen-rich blood from the lungs and returns it to the

heart

LEFT

ATRIUM • Receives oxygen-rich blood from the pulmonary veins

RIGHT

ATRIUM

• Receives oxygen-poor blood from the body

through the vena cavae

LEFT

VENTRICLE

• Receives oxygen-rich blood from the contraction of the left

atrium causing the valve to open; has a much more muscular

wall as it pumps blood to the whole body

AORTA • Receives oxygen-rich blood from the contraction of the left

ventricle causing the valve to open sending oxygenated

blood to the body; largest artery in the body

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Science 30 – Unit A – Living Systems Respond to Their Environment

Practice:

Label the diagram

Pg. 19 #1-6

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Science 30 – Unit A – Living Systems Respond to Their Environment

1. Beginning with the vena cavae, the order of the structures of the cardiovascular

system through which blood flows is as follows: vena cavae, right atrium, right

ventricle, lungs, left atrium, left ventricle, aorta, and body.

2. a. IV The pulmonary veins receive oxygenated blood from the lungs.

b. II The aorta sends oxygenated blood to the body.

c. V The semilunar valve prevents the backflow of blood into the heart.

d. VI The septum separates the right and left halves of the heart.

e. I The vena cavae collects deoxygenated blood from the body.

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Science 30 – Unit A – Living Systems Respond to Their Environment

b. Regular cardiovascular exercise increases the elasticity of the heart tissue—this gives

the heart a greater capacity to expand and, therefore, a larger stroke volume. Since

the stroke volume is larger, an increased volume of blood is pumped to the body during

each of the heart’s cycles, so the athlete’s body can get the necessary amount of

blood with fewer heartbeats. An inactive person tends to have a heart with less elastic

tissue, so this heart has a decreased ability to expand and, therefore, a reduced stroke

volume. This reduction in blood volume pumped to the body during each of the heart’s

cycles means that it takes more heartbeats every minute to supply the body with the

required amount of blood.

4. The left ventricle of the heart pumps blood to the body and needs to do so with

significant force, whereas the right ventricle needs to pump blood only to the

lungs. Therefore, the left ventricle is much more developed.

5. The systole is the complete contraction of one of the heart’s chambers. A

ventricular systole occurs when the ventricles contract, while an atrial systole

occurs when the atria contract. The diastole is the relaxation stage of the heart’s

cycle, when neither the ventricles nor the atria are contracting. Together, the

systole and diastole make up one complete heartbeat.

6. A heart-rate monitor is used to help an exercising person maintain a desired

exercise intensity as determined by the heart rate. The intensity could be used to

aid weight loss and/or an increased cardiovascular performance, or it could be

used to ensure that the heart rate remains at a safe level.

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Science 30 – Unit A – Living Systems Respond to Their Environment

1.2 CIRCULATION PATHWAYS AND HEART BEAT

The heart is made up mostly of muscle cells that contract

on their own and in unison (“myogenic tissue”)

Specialized nerve tissue helps to coordinate the muscle

contractions

Both sides of the heart fill with blood at the same time

and work as parallel pumps

Both atria will fill with blood and contract at the same

time, the valves will open allowing blood to flow to

the ventricles

Both ventricles will then simultaneously contract

There are 3 vascular loops in the circulatory system:

Pulmonary system (lung loop)

o From the heart to the lungs and back

o Picks up O2; dumps CO2

Systemic system (body loop)

o From the lungs to the whole body and

back

o Picks up CO2; dumps O2

Coronary system (heart loop)

- Electrocardiograms (ECG or EKG)

are machines used to monitor the

heart.

- When the ventricles are contracting

randomly and ineffectively (like a

spasm), it is called ventricular

fibrillation; an electric shock from a

defibrillator can jolt the heartbeat

back into rhythm.

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Science 30 – Unit A – Living Systems Respond to Their Environment

The heart beat has two phases:

1. DIASTOLIC – the atria and ventricles are relaxing filling with blood; the semilunar

valves close causing a “dub” sound

2. SYSTOLIC – the atria and the ventricles contract forcing blood to move; the

artrioventricular valves close causing a “lub” sound

BLOOD PRESSURE

The force per unit area that blood exerts on the walls of blood vessels.

It is measured by a sphygmomanometer

It is measured in millimetres of mercury (mm Hg)

It is given as systolic over diastolic pressure

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Science 30 – Unit A – Living Systems Respond to Their Environment

Normal range for blood pressure:

90 to 135 systolic

50 to 90 diastolic

120/80 is the “textbook” normal pressure

Hypertension is chronic abnormally high pressure above 140/90

MEASURING BLOOD PRESSURE:

Put the inflatable cuff around the upper arm and inflate to a pressure of about

145 – 160 mm Hg. This blocks the flow of blood in the major artery.

Using a stethoscope, listen for the sound of the blood in the artery. As the

pressure is slowly reduced, blood forcing its way through the artery is heard. This

FIRST SOUND heard is the pressure recorded as the systolic value.

When the sound is no longer heard, the pressure value is recorded – this is the

diastolic pressure.

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Science 30 – Unit A – Living Systems Respond to Their Environment

1.3 BLOOD VESSELS

1. ARTERIES:

o carry blood away from the heart under high pressure

o have muscle tissue and elastic fibres

o ARTERIOLE: a small artery that connects an artery to a capillary

2. CAPILLARIES

o site of exchange between tissue cells and the blood

o vast networks of thin blood vessels

o blood cells move in single file

o capillary bed is a network of capillaries in a particular part of the body

3. VEINS

o carry blood to the hear under low pressure; have one-way valves to

prevent backflow of blood

o VENULES connect capillaries to veins

o have wide openings surrounded by thin muscle and connective tissue

o contractions of muscles also helps move blood up veins in the legs back

to the heart

high pressure blood

flowing into capillary

from arteriole

low pressure blood

flowing into venules

from capillary

tissue cells

spaces between tissue

cells to allow diffusion

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Science 30 – Unit A – Living Systems Respond to Their Environment

Practice:

Label the diagram

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Science 30 – Unit A – Living Systems Respond to Their Environment

Pg. 33 # 1-6

1. The following table compares arteries, veins, and capillaries.

Arteries Veins Capillaries

2. a. People with diabetes would no longer have to inject themselves with insulin. Using

an inhaler would be a much less painful and invasive delivery system, and there would

be less chance of infection from poor sanitation at the injection site or scarring from

repeated injections. In terms of disposal and safety, it is much more convenient to carry

around an inhaler than it is to carry syringes.

b. The path from fat under the skin is as follows: a fat capillary under the skin; a venule;

a vein; the vena cava; the right atrium; the right ventricle; the pulmonary arteries; the

lungs; the pulmonary veins; the left atrium; the left ventricle; the aorta; several arteries;

an arteriole; and end at a capillary next to a target cell in the liver.

c. Inhaled insulin would take the following path from the lungs to a target cell in the

liver: the lungs; the capillaries and venules of lung tissue; the pulmonary veins; the left

atrium; the left ventricle; the aorta; several arteries; an arteriole; and then to a capillary

next to the target liver cell.

d. The inhaled delivery system would be faster because the needed chemical would

not have to first travel through the de-oxygenated parts of the circulatory system. This

quicker delivery would be an advantage over the hypodermic delivery system.

3. Factors that can cause a person’s blood pressure to increase include a stronger

contraction of the heart, a higher heart rate, and a loss in the elasticity of the arteries.

Higher blood pressure readings can also be attributed to anxiety level, exercise, a

greater than normal amount of blood in vessels, viscosity (thickness) of the blood,

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Science 30 – Unit A – Living Systems Respond to Their Environment

chemicals such as caffeine or epinephrine, kidney disease, or a narrowing of the blood

vessels due to a poor diet.

4. If an artery is cut, the greater pressure in an artery means that the blood flows out

more quickly and forcefully than it would in a vein. It follows that there is a greater risk of

blood loss with a cut artery than there is with a cut vein.

5. The following illustration is a sketch of a capillary bed.

6. Contracting muscles in the lower legs help to massage the blood in the lower legs

back toward the heart. Once the leg muscles push the blood in the veins, the valves

are able to direct this blood.

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Science 30 – Unit A – Living Systems Respond to Their Environment

1.4 BLOOD COMPOSITION

The blood is a tissue (made of cells), a fluid called plasma and blood proteins.

The cells include red blood cells, white blood cells and platelets.

Plasma is mainly water with dissolved solutes (e.g. glucose, amino acids).

PLASMA

Yellowish liquid with dissolved or suspended substances

that makes up more than half of blood.

91% water, 7% proteins, 2% nutrients

Transports substances in the blood

WHITE BLOOD CELLS (a.k.a. leukocytes)

part of the immune system (fight disease)

made from special cells in the bone marrow

much larger than red blood cells but are fewer in

number

have a nucleus

PLATELETS

Platelets are small (1/5 size of red blood cells) with an irregular shape

the sticky surface lets them form clots to stop bleeding

RED BLOOD CELLS (a.k.a. erthrocytes)

most numerous (5 million per mm3 of blood) cell type in blood – most common

blood cell in healthy people

carry oxygen using hemoglobin

“bi-concave” shape

no nucleus (enucleated)

develop in the bone marrow and have a life span of about 120 days before

being recycled by white blood cells

www.dreamstime.com

Red blood cells biconcave

shape allow them to slide

through the blood vessels with

ease.

www.dailymail.co.uk

White blood cells lack a

colour pigment and only

has a life span of 13 – 20

days.

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Platelets call on a protein

to produce FIBRINOGEN,

present in the plasms, to

clot blood.

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Science 30 – Unit A – Living Systems Respond to Their Environment

ROLE OF BLOOD COMPONENTS

1. TRANSPORTATION

HEMOGLOBIN (Hb)

Hemoglobin is an iron-containing pigment that binds oxygen to facilitate its

movement in the circulatory system.

Each red blood cell contains hundreds of millions Hb molecules – the lack of a

nucleus allows for a red blood cell to carry the extra hemoglobin.

As blood passes through the lungs, the hemoglobin molecules picks up oxygen

to form oxyhemoglobin. The oxygen is transported to the body tissues through

the capillary beds.

Carbon monoxide binds irreversibly to hemoglobin thereby inactivating it

Draw a diagram to show the transport of oxyhemoglobin to the body tissues (refer to

page 37).

PLASMA

Holds and transports

o Cells of the blood

o Dissolved waste carbon dioxide from capillaries to the lungs

o Urea – a waste product from the liver, filtered by the kidneys to become

urine

o Hormones from glands

o Digested nutrients such as glucose, amino acids, vitamins and minerals

o Proteins such as antibodies (involved in the immune system) and

fibrinogen to aid in blood clotting

2007 Alberta Education

Name: __________________________________

Science 30 – Unit A – Living Systems Respond to Their Environment

2. BLOOD CLOTTING

Platelets are responsible for clotting the blood.

Fibrin is a thread-like insoluble protein formed from firbrinogen.

A blood clot is a jelly-like, solid mass of red blood cells caught up in a net of fibrin

fibres.

PROBLEMS WITH BLOOD CLOTTING

o High fat diets can lead to artery walls becoming rough causing platelets

to stick and produce a blood clot in the artery.

o Blood clots in the arteries can lead to heart attacks or strokes.

o Hemophilia is a blood disorder that inhibits ability for the blood to clot,

which may lead to excessive bleeding.

3. DEFENSE AGAINST PATHOGENS

White blood cells increase in number when disease-causing organisms enter the

body.

The increase in the white blood cells helps the body fight off infections.

4. DISTRIBUTION OF THERMAL ENERGY

To keep the thermal energy distributed evenly throughout the body, blood acts

as a convective fluid to keep the tissues of the body from overheating.

Hormones such as epinephrine, norepinephrine, and thyroid hormone are

carried through the circulatory system to help with heat in the body.

Practice:

Pg 41 #1, 3, 4, 5

When the skin is

cut, blood starts

leaking out to

wash away dirt

and germs

Platelets rupture

and convert

fibrinogen into

threads of fibrin

Red blood cells

get caught in the

fibrin net to form a

blood clot

The clot hardens

to form a

protective scab

Name: __________________________________

Science 30 – Unit A – Living Systems Respond to Their Environment

1. a. The four components of blood from most abundant to least abundant are plasma,

red blood cells, white blood cells, and platelets.

b. The following diagram illustrates each component of question 1.a.

3. Carbon monoxide has a much greater affinity for hemoglobin than does oxygen, so

carbon monoxide will preferentially bind to hemoglobin and form a stable bond. As a

result, if you inhale even low concentrations of carbon monoxide, more hemoglobin

combines with carbon monoxide than does oxygen. If carbon monoxide is taking the

place of oxygen on the red blood cells, that means that the blood cannot transport

needed oxygen to the body’s cells. A person could suffocate even though he or she is

able to breathe normally.

4. Anticoagulants that thin blood make it easier for blood to flow through damaged or

constricted blood vessels.

5. a. Having improperly functioning white blood cells means that the person is not able

to fight off disease-causing organisms.

b. A transplant of healthy bone marrow means that healthy and normally functioning

white blood cells will be produced.