Circulatory System

Chapter 47-1

p. 931-937

The Circulatory System

Figure 23.4 A trip through the human

cardiovascular system. This diagram traces

the path of blood as it makes one full trip

around the body. If we consider the

circulatory system as a whole, the

pulmonary and systemic circuits operate

simultaneously. The two ventricles pump

almost in unison, sending some blood

through the pulmonary circuit and the rest

through the systemic circuit at the same

time. (Note that the left side of the heart is

on the right side of the figure—and vice

versa—because the body is viewed from the

front.)

The Heart – central organ of the cardiovascular

system, pumps blood through the body

Structures of the heart:

• Pericardium – saclike

membrane surrounding

the heart

• Septum – vertically

divides the heart

• Atria (singular = atrium) –

upper chambers of the

heart

• Ventricles – lower

chambers of the heart

Valves of the Heart

• Atrioventricular (AV) valves –

separates the each atrium from

the ventricle below it, prevent

blood from flowing backward

– Tricuspid valve

– Mitral/bicuspid valve

• Semilunar (SL) valve –

separates the ventricles from

the large vessels on the side of

the heart, prevent blood from

flowing back into the heart

– Pulmonary valve

– Aortic valve

Circulation in the Heart

1. Superior vena cava –

deoxygenated blood

enters the heart

2. Right atrium –

deoxygenated blood is

collected

3. Right ventricle –

deoxygenated blood is

pumped out

4. Pulmonary arteries –

carries deoxygenated

blood to the lungs

Circulation in the Heart

1. Pulmonary veins –

carries oxygenated

blood from the lungs to

the heart

2. Left atrium –

oxygenated blood is

collected

3. Left ventricle –

oxygenated blood is

pumped out of the heart

4. Aorta – carries

oxygenated blood to the

body

Circulation in the Heart

To the LungsTo the Lungs

From the LungsFrom the Lungs

Checkpoint

1. Which chambers of the heart receive blood?

The atria (plural for atrium).

2. Which chambers of the heart pump blood?

The ventricles.

3. Where do the pulmonary arteries & veins lead to/from?

The Lungs.

Control of the Heartbeat –cardiac muscle cells contract in waves

• Sinoatrial (SA) node – a group

of specialized heart-muscle

cells located in the right atrium

that cause the atria to contract

– ―Pacemaker‖ – regulates the

contraction of the entire heart

• Atrioventricular (AV) node –

located in the septum, relays

the electrical impulse to the

ventricles and cause them to

contract

Phases of the heartbeat

• Systole – ventricles

contract

– AV valves - close

– SL valves - open

– Blood - flows out of

the heart

• Diastole – ventricles

relax

– AV valves - open

– SL valves – close

Blood Vessels – transport blood

throughout the body• Arties – blood vessels

that carry blood away

from the heart

• Capillaries – tiny blood

vessels that reach all of

the body’s cells

– Gas exchange – oxygen &

carbon dioxide are

exchanged between cells &

the capillaries

• VeINs – blood vessels

that carry blood into the

heart

Blood Pressure

• Blood pressure – force of

blood against blood vessel

walls

– Systolic pressure – pressure

of blood when ventricles

contract

– Diasolic pressure – pressure

remaining when ventricles

relax

– Normal blood pressure =

120/80 (systolic/diastolic)

• Hypertension – high blood

pressure, places strain on the

blood vessels & increases the

chance they will burst

Pulmonary Circulation - blood

travels between the heart & lungs

• Capillaries in the

lungs – carbon

dioxide diffuses out of

the blood & oxygen

diffuses in

Systemic Circulation - blood travels

between the heart & all other body tissues

• Coronary circulation –

supplies blood to the heart

• Renal circulation – supplies

blood to the kidneys

• Hepatic portal circulation –

blood picks up nutrients

from the small intestine &

carries them to the liver to

be used or stored

Checkpoint

1. What controls the SA & AV nodes?The autonomic nervous system.

2. What does a high blood pressure indicate?Strain on the blood vessels.

3. Where does gas exchange occur during pulmonary circulation?

In the capillaries of the lungs.

4. Where does gas exchange occur during systemic circulation?

In the capillaries in the body.

Essential Skill

3-2. Explain how the Circulatory System

and Respiratory System complement

each other in providing cells with

nutrients and removing toxic waste

products. (CSS: 9a)