The Circulatory System

Getting to the heart of the matter.

Are you pumped?

The Circulatory System •  System comprised of a heart, blood

vessels, & lymph glands •  Work together to supply the body

tissues with nourishment and collect waste materials.

Our Vascular System

•  Comprised of 3 main vessels: –  Arteries

• Branch into smaller arteries called ARTERIOLES

–  Capillaries –  Veins

• Connected to capillary bed via into smaller veins called VENULES

Our Vascular System

Arteries

•  Carries oxygen-rich blood from heart to other parts of body

•  Thick walled •  Elastic-like tissues

• To withstand the pressure from the heart’s beating

Capillaries

•  Connect arteries to veins •  Located all throughout body tissues •  Thin-walled •  Small diameter

– Blood cells pass through in single file •  Semi-permeable membrane allows

nutrients, oxygen, and water to diffuse from blood into the tissues

•  Waste products (ie. CO2) diffuse from the tissues into the blood.

Veins

•  Veins are the BV that bring blood back to the heart

•  Thin, collapsible walls •  Valves

– Prevent blood from reversing flow

X-Section of Blood Vessels

Our Circulatory system is a double circulatory system. It has two parts:

the left side of the system

deals with oxygenated

blood.

the right side of the system

deals with deoxygenated

blood.

Lungs

Body cells

The total system is divided into two main parts: Pulmonary & Systemic Circulation

1.  Pulmonary circulation

-  takes blood from heart to the lungs -  returns OXYGENATED blood to the heart -  main parts: heart, pulmonary arteries,

capillaries of lung, pulmonary veins

Pulmonary Circulation

Red portion of heart and red blood vessels carry oxygen-rich blood.

Blue portion of heart and blue blood vessels carry oxygen-poor blood.

Flow of Blood in Pulmonary Circulation: 1. Blood that is low in O2 returns to heart thru 2

large veins: superior vena cava & inferior vena cava.

2. The de-oxygenated blood enters RIGHT ATRIUM of heart.

3. The blood passes through right atrioventricular (tricuspid) valve into RIGHT VENTRICLE.

4. Right ventricle pumps blood through pulmonary valve into pulmonary artery.

Flow of Blood in Pulmonary Circulation: 5. Pulmonary artery quickly divides into two

branches. 6. Each branch of the pulmonary artery carries

the blood to the LUNGS 7. In the lungs: pulmonary arteries branch into

capillaries that surround the ALVEOLI (site of gas exchange in the respiratory system).

8. Through diffusion, CO2 moves from blood into alveoli. O2 moves from alveoli into blood.

Flow of Blood in Pulmonary Circulation: 9. Oxygenated blood returns to heart through

pulmonary vein into the left atrium. 10. From the left atrium, blood flows thru the left

atrioventricular (bicuspid) valve into the left ventricle.

11. Thick-walled left ventricle pumps blood through aortic valve into the aorta.

The pressure required is much less for

pulmonary circ. than systemic. Why? How does this relate to muscle mass on each

side of the heart?

De-oxygenate Blood: - dark red / brownish red

Oxygenate Blood - bright red

NOTE: In Pulmonary Circulation: - deoxygenated blood is carried via pulmonary arteries - oxygenated blood is carried via pulmonary veins

In Systemic Circulation: - oxygenated blood is carried via arteries - de-oxygenated blood is carried via veins

2. Systemic circulation -  Flow of oxygenated blood from heart to

tissues of ALL parts of body -  returns DE-OXYGENATED blood to the

heart -  main parts: blood vessels (arteries,

capillaries, veins) -  Delivers O2 and nutrients to tissues via

arteries -  Blood is filtered during systemic circ. by

kidneys and liver.

Flow of Blood Through Systemic Circulation: 1.  Oxygen-rich blood leaves left ventricle of heart

through aorta (=largest artery) 2.  Left and right coronary arteries branch from

aorta and carry fresh blood to heart muscle itself (often clots form here & leads to a heart attack).

3.  Coronary veins quickly return that blood back to heart.

4.  Brachiocephalic truck is next branch from aorta.

-  Carotid arteries branch off and carry O2 to neck and head (blood returns via jugular veins)

-  Left and Right Brachial arteries branch to supply blood to shoulders and forelegs

5. Thoracic aorta (another portion of the aorta) goes from heart through the thoracic cavity to the diaphragm.

6. Celiac Artery branches from aorta to gastric (supplies

stomach), splenic (supplies spleen) and hepatic (supplies liver) arteries.

7. Mesentaric arteries branch from abdominal aorta to carry blood to small and large intestines .

8. Renal arteries branch from abdominal aorta to supply kidneys. - arteries branch from here to supply testicles (spermatic arteries) and to female reproductive system (uteroovarian arteries).

9. Abdominal aorta ends to branch into internal and external iliac arteries. - Internal iliac artery: supplies blood to pelvic and hip region - External iliac artery -branches to femoral arteries. Femoral arteries supply blood to hind legs.

10. Veins accompany arteries and have similar names.

- Veins always larger than arteries - usually more visible (closer to skin) - most empty de-oxygenated blood into vena cavas.

The Heart