2 ­ 2201 ­ Circulation.notebook March 07, 2015

Oct 11­3:27 PM

Unit 3

• Circulatory system

• The heart

• Blood

• Blood Pressure

• Circulatory Disorders

Maintaining Dynamic Equilibrium

Feb 6­4:30 PM

Circulatory System p.304­307

If an organism is small and flat it can transport nutrients and wastes by diffusion.

For a multi­billion cell organism like humans, diffusion is not quick enough to provide nutrients nor remove wastes.

Therefore most large organisms have a circulatory system.

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:30 PM

For humans an efficient circulatory system is essential because:

1. It transports oxygen, energy and the basic building blocks of life to all parts of the body.

2. It helps maintain a constant temperature in all parts of the body.

3. It removes carbon dioxide and metabolic wastes from cells.

4. It plays an important role in the body’s defenses against pathogens (things that make us sick, e.g. bacteria).

Circulatory System

Feb 6­4:30 PM

There are 4 main parts of the circulatory system:

1. Arteries2. Veins3. Capillaries4. Heart

Parts of the Circulatory System

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:30 PM

1. Arteries ­ p. 306Carry blood away from the heart. Most carry oxygenated blood

Three layers:

1. outer layer = elastic connective tissue.2. middle layer = elastic fibers and smooth muscle.3. inner layer = single layer of smooth cells that reduce friction.

Elastic walls expand as waves of blood pressure pass through.

Snaps back into shape to aide in pumping.

Blood pressure highest.

Feb 6­4:31 PM

2. Veins ­ p. 307

Carry blood toward the heart

Most carry deoxygenated blood

Thinner walls than arteries but have a larger (2x) diameter.

Blood flow is slow

Don’t contract. Gravity and movement of muscles aid in blood flow

Have one way valves to prevent blood from flowing backward.

Blood pressure is low.

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:31 PM

3. Capillaries ­ p.307

Smallest blood vessels

Connect arteries and veins

Site where exchange between blood and other parts of the body occur.

Feb 6­4:31 PM

2 ­ 2201 ­ Circulation.notebook March 07, 2015

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4. Heart ­ p. 314 ­315

4 chambers: 2 atria + 2 ventricles

Made of cardiac muscle tissue.

Can contract repeatedly without getting tired.

Surrounded by a protective membrane called the pericardium.

Feb 6­4:32 PM

4. Heart

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:32 PM

4. Heart

Feb 6­4:35 PM

Blood p.308­313

Blood is an essential part of the circulatory system. It aids in transportation of many molecules throughout the body.

Blood is a tissue, made of 45% cells and 55% liquid called plasma.

There are 4 parts that make up Blood:

1. Red blood cells (erythrocytes)

• They make up 44% of the total volume.• They are produced in the bone marrow.• They live only a short time (3 – 4 months).• They are small cells.

Function: To carry oxygen to other cells and take carbon dioxide away.

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:36 PM

Blood2. White Blood Cells

They make up 1% of blood volume.

They are produced in the bone marro (macrophages) or spleen (lymphocytes).

• They live a few hours to a few days.• They are produced mainly in response to an infection.

• They are larger than red blood cells.

Function: To attack invaders.

Feb 6­4:36 PM

Blood3. Platelets (thrombocytes)

• They are produced in bone marrow and lungs.• They live 7 – 10 days.• They are small fragments of cells.

Function: To aid in blood clotting.

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:37 PM

Blood4. Plasma

• The fluid of blood.• 92% water 7% proteins.• It is yellow coloured.

Function: Aids in movement of cells and transporting CO2.

Apr 13­3:28 PM

Blood Pressure p.323­324

The pressure of blood against the walls of blood vessels.

Blood pressure is highest at the aorta and decreases as it gets further away from the heart.

It is the lowest in the vena cava.

It is expressed as a ratio:

Systolic pressure Pressure during contraction Diastolic pressure Pressure between contractions

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Apr 13­3:28 PM

Blood Pressure

Systolic pressure is the highest.

Diastolic is the pressure exerted on blood vessels most of the time.

A high diastolic pressure is more serious than a high systolic pressure, because it is the lowest pressure your arteries ever have.

Apr 26­2:16 PM

Circulatory Disorders p.324­26

1. Hypertension: Chronic high blood pressure.

This can occur as a result of two conditions:

A) Increase in the volume of the blood or;B) Reduced elasticity of the arteries

An increase in blood volume can be related to diet.

Examples: one high in salt, stimulants (coffee, nicotine), or saturated fat.

Hypertension can also be increased by the following two conditions.

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Apr 26­2:16 PM

Circulatory Disorders1. Atherosclerosis

Deposits of cholesterol plaques on the inside of an artery.

This decreases the diameter of arteries and blood flow

Coronary artery disease occurs when this condition is present in the arteries that supply the heart

Apr 26­2:16 PM

Circulatory Disorders

2. Arteriosclerosis

Deposits of cholesterol or other fatty material becomes deposited under the inner layer of the artery.

This can damage platelets which cause blood clots and block blood flow.

Arteries also become less elastic.

If the flow of oxygen to the brain is slowed a stroke can occur.

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Apr 26­2:16 PM

Treatment of Circulatory Disorders p.326­328

Treatment of circulatory disorders can include one or more of the following:

1. Diet change ­ Less saturated fat & cholesterol, with more fruits and vegetables reduce plaques.

2. Aspirin ­ Prevents platelets from sticking together, so it prevents blood clots.

3. Angioplasty – A fine plastic tube is inserted into a clogged artery. A balloon is pushed out the tip and inflated. This forces the vessel open.

Apr 26­2:16 PM

4. Coronary bypass surgery – This corrects blockages to the heart.

A blood vessel from another part of the body (e.g. leg) is grafted (sewn on) to the aorta and then to a point beyond the blockage.

A double bypass means two blood vessels were added.

This is done by stopping the heart An external pump circulates blood. The blocked vessel is clamped

Sometimes the heart is not stopped and a shunt (tube) is used to direct blood away from the site of the operation.

The shunt provides a bloodless field of view and uninterrupted blood flow.

Treatment of Circulatory Disorders

2 ­ 2201 ­ Circulation.notebook March 07, 2015

Feb 6­4:32 PM

Lab!