The Cardiovascular System

Biology 9Ms. Marcos

Questions you can answer after learning about the Cardiovascular System:

• Why could you faint if you stand at attention for a long time?

• Why can you feel nauseous if you are in a sudden stressful situation?

• What makes the Boom-boom sound of a heart beat?• How is the heart disconnected during open heart surgery?• Why does your heart rate increase with exercise?• What is a “pacemaker” and what does it do?• What is hypertension? What is hypotension?

Big Questions about the Cardiovascular System:

• Why do we need a cardiovascular system?

• What does blood do?

• How does blood move around the body?

Answer these questions on your own, then share your

answers with a partner.

Answer these questions on your own, then share your

answers with a partner. Watch Tim and Moby explain about

the cardiovascular system and add

more information to your answer!Watch Tim and Moby explain about

the cardiovascular system and add

more information to your answer!

Pulmonary veinVein

Pulmonary artery Artery

Body capillaries

Lung (pulmonary) capillaries

Label the

blood vessels!Label the

blood vessels!

What types of blood vessels are there?• Arteries:

– Carry blood AWAY from the heart– A few, strong vessels

• Veins:– Carry blood TO the heart– More, weak vessels

• Capillaries:– Exchange gases and nutrients in the blood with tissues– Many, very small vessels

Now try to

label this one!Now try to

label this one!

Body capillaries

Body capillaries

Lung capillariesLung capillaries

Pulmonary vein Pulmonary vein

Pulmonary arteryPulmonary artery

Artery

Artery

Vein

Vein

Left VentricleRight Ventricle

Right AtriumLeft Atrium

A closer look…

• What are arterioles?– Small arteries (one artery leads to more arterioles)

• What are venules?– Small veins (small venules lead to one vein)

• How large and flexible are:– Arteries and arterioles?– Veins and venules?– Capillaries? See the diagram on the

next slide!See the diagram on the

next slide!

Thick muscle

(holds high

pressure blood)

Thick muscle

(holds high

pressure blood)

Thin muscle

(only low pressure

blood inside)

Thin muscle

(only low pressure

blood inside)

Thin walls

Allow diffusionThin walls

Allow diffusionValve

(prevents backflow)

Valve(prevents backflow)

ArteryArtery VeinVein

CapillariesCapillaries

Explain the differences

•Which one carries blood away from the heart?

•Which one has thicker muscle?

•Why does it need to be thicker?

•Which one carries blood to the heart?

•Which one has a valve?•Why does it need a valve?

Why are capillaries so small?

BAD stuff going IN

from body tissues:

Wastes, CO2

BAD stuff going IN

from body tissues:

Wastes, CO2

GOOD stuff going

OUT to body tissues:

Nutrients, O2

GOOD stuff going

OUT to body tissues:

Nutrients, O2

They need to DIFFUSE things

IN and OUT

They need to DIFFUSE things

IN and OUT

Are they always filled with blood?

Are they always filled with blood?

Why would you want to cut off blood flow to capillaries in a certain area?

Small muscles

stop blood flow

Small muscles

stop blood flow

Only the parts that NEED blood right away have it(Many body parts take

turns getting blood)

Only the parts that NEED blood right away have it(Many body parts take

turns getting blood)

Hint: Injury!Hint: Injury!

Changing blood flow… an example

If you are being chased by a

BEAR…

You need to get away FAST!If you are being chased by a

BEAR…

You need to get away FAST!Send blood away

from the digestive system

Send blood away from the digestive

system

Send blood to the brain and musclesSend blood to the brain and muscles

Result: You might feel nauseous because of less blood going to your stomach

Result: You might feel nauseous because of less blood going to your stomach

How does blood get back to the heartafter going through the capillaries?

Muscle pushes on

the veinMuscle pushes on

the vein

Valve lets blood flow

only in one direction

Valve lets blood flow

only in one direction

Blood returns to the heartBlood returns to the heart

How veins work… an example

Activity:

Raise one hand and keep the other

hand down.

Wait 1 minute.

Now look at your palms!

Were your hands different colors?Why?

When guards stand still for a long time, the blood moves down to their feet and can’t get back up. It can cause them to faint.

Explain this using what you know

about veins and valves!

The Heart: A few definitions

• Myocardium– Heart muscle

• Pericardium– Tissue surrounding the heart

• Pericardial sac– Tissue sac with liquid around the heart

Latin roots: Myo = MuscleCardium = HeartPeri = Around

Latin roots: Myo = MuscleCardium = HeartPeri = Around

Aorta

Pulmonary artery

Pulmonary artery

Left Atrium

Pulmonary veins

Pulmonary veins

Vena cava

Vena cava

Semilunar valveSemilunar valve

AV valveAV valve

Left ventricleRight ventricle

Right Atrium

Label the

parts of the

heart!Label the

parts of the

heart!

Watch it happen!

Check out these animations:•The heart parts QUIZ•The heart from the outside•The heart both inside and outside•The valves•The valves from the inside

What makes the sound of your heart beat?

What would happen if…

• You had a hole in your septum (the dividing muscle between the right and left

ventricles)?

• You had a hole between your atria?

• You had a connection between your aorta and your pulmonary arteries?

How do you control heart contraction?

• Systole is…– When the heart muscle contracts

• Diastole is…– When the heart muscle relaxes

• Nodal tissue– Is very special… it has both nerve and muscle tissue

• SA node (sino-artrial node)

– Gets the signal from the brain and makes the atria contract

– Sends the signal to the AV node• AV node (atrio-ventricular node)

– Makes the ventricles contract all together

Pacemaker(SA node)

1 2 3 4

Rightatrium

Rightventricle

AV nodeSpecializedmuscle fibers

ECG

What does blood pressure mean?

• What is your pulse?Does it measure blood flow in arteries or veins?– Your pulse is a wave of blood moving through your

arteries

• What is blood pressure?Which vessels have the highest pressure?– Arteries have the highest pressure, then capillaries,

then veins• Muscles need to push the blood back to the heart through

your veins

How do you measure blood pressure?

Watch the Blood Pressure Animation!

• What is normal blood pressure?– Usually around 120 / 80 mmHg

• Why is blood pressure written as two numbers?– The first number means…

• When the ventricles contract and push blood through arteries

– The second number means…• When the ventricles relax and the blood keeps moving

through (at lower pressure)

Which is systolic and which is diastolic pressure?

SystolicSystolic

DiastolicDiastolic

Blood pressure problems

• Hypotension is – when blood pressure is too low

• Hypertension is – when blood pressure is too high

Put the following terms in order:Right Atrium Left Atrium Pulmonary Veins

Venules Arteries Veins

Arterioles Right Ventricle Body Capillaries

Superior/Inferior Vena Cava

Lung Capillaries Pulmonary Arteries

Aorta Semilunar valve Left Ventricle

Semilunar valve AV valve AV valve

Check your answers with these animations:

• How the blood circulates

• Music Video