Arteries and veins This Link shows what the arteries actually look like on a living person in surgeryLearning Objectives

Identify all the major arteries and veins of the circulatory system and show how they connect.

Trace a drop of blood from your left middle toe to your right middle finger.

Describe the structure of arteries and veins and explain the difference between the two.

Explain the significance of blood being contained within a closed system How your heart works. How stuff works/heart

The circulatory system is extremely important for sustaining life. Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products, maintenance of optimum pH, and the mobility of the elements, proteins and cells of the immune system. myocardial infarction and stroke each may directly result from an arterial system that has been slowly and progressively compromised by years of deterioration.

VEINS

Veins function to return poorly oxygenated blood to the heart, and are essentially tubes that collapse when their lumen are not filled with blood. The thick, outer-most layer of a vein is made of collagen, wrapped in bands of smooth muscle while the interior is lined with epithelial cells called intima. Most veins have one-

way flaps called venous valves that prevent blood from flowing back and pooling in the lower extremities due to the effects of gravity. The precise location of veins is much more variable from person to person than that of arteries.

ARTERIESArteries are blood vessels that carry blood away from the heart (as opposed to veins, blood vessels carrying blood toward the heart). All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.

The artery is has three layers: A muscular middle which is very elastic and strong, an outer layer of tissue, and an inner layer of smooth epithelial cells that allow the blood to flow easily.

The muscular wall of the artery actually helps the heart to pump blood. When your heart beats the artery expands with blood. Because the artery keeps pace with the heart

you can actually measure how many heart beats per minute you have by counting the contractions of the artery (pulse rate)

Arteries also deliver oxygen rich blood to the capillaries where the actual exchange of of carbon dioxide and oxygen happen. Looking at the image you can see that they have different wall thicknesses. The capillary wall is only 1 cell thick - this is to allow substances to diffuse across it(ie to give oxygen to cells and retrieve the CO2 from cells. One of the reason the blood is at higher pressure in the arteries is that there is a thick muscle layer and this creates a small volume for the blood to pass through. The thick muscle layer is there to withstand the high pressure. In the veins, the semilunar valves stop the blood from flowing backwards, as it is traveling at a very low pressure and is often moving against gravity. The contraction of the muscles also helps the blood in the veins to be pushed up.

Looking at this image you can see that they have different wall thicknesses. The capillary wall is only 1 cell thick - this is to allow substances to diffuse across it(ie to give oxygen to cells and retrieve the CO2 from cells. One of the reason the blood is at higher pressure in the arteries is that there is a thick muscle layer and this creates a small volume for the blood to pass through. The thick muscle layer is there to withstand the high pressure. In the veins, the semilunar valves stop the blood from flowing backwards, as it is traveling at a very low pressure and is often moving against gravity. The contraction of the muscles also helps the blood in the veins to be pushed up.

The

outermost layer is known as the tunica externa and is composed of connective tissue. Inside this layer is the tunica media, or media, which is made up of smooth muscle cells and elastic tissue. The innermost layer, which is in direct contact with the flow of blood is the tunica intima. This layer is made up of mainly endothelial cells. The hollow internal cavity in which the blood flows is called the lumen.

AortaThe aorta is the root systemic artery. It receives blood directly from the left ventricle of the heart via the aortic valve. As the aorta branches, and these arteries branch in turn, they become successively smaller in diameter, down to the arteriole. The arterioles supply capillaries which in turn empty into venules.

The Next Section will explore major arteries and veins,by body region.

General arterial flow out of the heart

Oxygenated blood is pumped out of the heart by the left ventricle and then enters the ascending aorta. (The left and right coronary arteries branch off directly from the walls of the ascending aorta.)

The ascending aorta then curves towards the left side of the body and forms the aortic arch. ( Three main arteries branch from the aortic arch they are 1. brachiocephalic trunk, 2. left common carotid and 3. left subclavian.

The aortic arch then projects inferiorly to form the descending thoracic aorta. ( The descending thoracic aorta then gives rise to the descending abdominal aorta, which separates into the left and right common illiac arteries.)

General venous return to the heart.

The veins that bring the poorly oxygenated blood back to the heart often share the same names as the arteries that take the oxygenated blood to the same area.

The left and right brachiocephalic veins drain the blood from the head, neck and upper limbs.

The left and right brachiocephalic veins then merge to form the superior vena cava, which drains directly into the right atrium of the heart.

All of the veins inferior to the diaphragm merge to form the inferior vena cava, which also drains directly into the right atrium.

Blood flow to the head and neck.

The left and right common carotid arteries supply most of the blood to the head and neck.

The travel parallel and immediately lateral to the trachea. At the superior border of the thyroid cartilage each artery divides into an external and

internal carotid artery the external supplying the structures external to the skull and the internal supplying the internal structures of the skull.

The external carotid artery supplies blood to several branches

1. superior thyroid artery. ( supplies thyroid gland, larynx, and some anterior neck muscles.)

2. ascending pharyngeal artery. (supplies the pharynx.) 3. lingual artery.

(supplies the tongue.)

4. facial artery. (supplies most of the facial region.)

5. occipital artery. (supplies the posterior portion of the scalp.)

6. posterior auricular artery. (supplies the ear and the scalp around the ear.)

7. maxillary artery. (supplies the teeth, gums, nasal cavity, and meninges.)

8. superficial temporal artery. (supplies the side of the head and the parotid gland.)

Venous return from the head and neck.

The venous return is accomplished through several smaller veins that merge to form the facial, superficial temporal, and maxillary veins.

These veins then merge and drain into either the internal jugular vein or the external jugular vein, which drain into the subclavian vein and then into the brachiocephalic vein and then into the superior vena cava.

Blood flow through the cranium

The internal carotid artery splits once it enters the carotid canal. It forms the anterior and middle cerebral arteries, which supply the brain and the

ophthalmic arteries which supply the eyes. The vertebral arteries form from the subclavian arteries before they enter the skull

through the foramen magnum. Once inside the skull they merge and form the basilar artery.

The basilar artery subdivides into many branches that are called the posterior cerebral arteries. (supply the cerebrum.)

The other major structure in the cranium is the cerebral arterial circle. This circle equalizes the blood pressure in the brain and can provide alternate channels should a vessel become blocked.

Venous return from the cranium

Blood is drained from the cranium through several large veins called dural venous sinuses.(there are no valves in the dural venous sinus system so blood can potentially flow in more than one direction.)

There are several components to the dural venous sinus system and they are:

1. Superior sagital sinus. (drains into one of the transverse sinuses usually the right one.)

2. Inferior sagital sinus. (occupies the interior free edge of the falx cerebri.) 3. Straight sinus. (formed by the merging of the inferior sagital sinus and the great

cerebral vein.) 4. Left and Right transverse sinuses. (these run horizontally along the internal margin

of the occipital bone.) 5. Left and Right sigmoid sinuses. (these are a continuation of the transverse sinuses

and they drain into the internal jugular veins.)

The internal jugular veins and subclavian veins merge to form the brachiocephalic veins and drain into the superior vena cava.

Blood flow through the abdominal cavity

Left and Right internal thoracic arteries emerge from the Left and Right subclavian arteries.

Each internal thoracic artery has the following branches.

1. Anterior intercostal arteries which supply the anterior intercostal spaces.

2. Musculophrenic artery which supplies the diaphragm. 3. Superior epigastric artery which supplies the superior abdominal

wall. 4. Inferior epigastric artery which supplies the inferior abdominal wall.

Left andRight costocervical trunks and thyrocervical trunks emerge from the subclavian arteries as well.

These arteries together form a horizontal vessel arc that spans a segment of the thoracic wall.

There are also five pairs of lumbar arteries and a median sacral artery that supply the lower portion of the thorax.

Venous drainage from the abdominal cavity

Anterior intercostal veins, a superior epigastric vein, and a musculophrenic vein merge to form the internal thoracic vein.

Each of the internal thoracic veins drains into its respective brachiocephalic vein. The inferior epigastric vein merges with the external illiac vein and then drains into

the inferior vena cava.

Blood flow through the thoracic organs LungsBronchial arteries: supplies the lungs Bronchial veins: drains blood from the lungs

Here is an article (from Access DNA) about Pulmonary Arterial Hypertension.

Esophagus

Esophageal arteries: supplies the esophagus above the abdominal cavity Esophageal veins: drain the esophageal wall.

Esophageal branches: supplies the esophagus in the abdominal cavity.

Diaphragm Superior phrenic arteries: supply the diaphragm

Superior phrenic veins: drain the diaphragm into the inferior vena cava

Musculophrenic arteries: supply the diaphragm

Inferior phrenic veins: drain the diaphragm into the inferior vena cava.

Inferior phrenic arteries: supply the diaphragm

Musculophrenic veins: drain the diaphragm into the internal thoracic veins.

Blood flow through the GI tract Celiac trunk: supplies the stomach, the liver, the spleen, and parts of the duodenum and pancreas.

Heptic portal vein: receives poorly oxygenated blood from the gastrointestinal organs.

Left and Right gastric artery: supplies the lesser curvature of the stomach.

Inferior mesenteric vein: drains the distal part of the large intestine, receives blood from the superior rectal vein, sigmoid, veins, and the left colic vein.

Splenic artery: supplies the spleen and part of the stomach.

Splenic vein: drains the spleen, receives blood from pancreatic veins, short gastric veins, and the right gastroepiploic vein.

Common hepatic artery: supplies the liver.

Superior mesenteric vein:drains the small intestine and part of the large intestine. It receives blood from the intestinal veins, pancreaticoduodenal veins, ileocolic vein, and right and middle colic veins.

Hepatic artery proper: supplies the liver via left and right hepatic arteries.

Gastroduodenal artery: supplies the lesser curvature of the stomach, the duodenum, and the pancreas.

Superior mesenteric artery: supplies most of the small intestine, part of the pancreas and part of the large intestine.

Intestinal arteries: supply the jejunum and ileum

Ileocolic artery: supplies the ileum, cecum, and the appendix.

Right colic artery: supplies the ascending colon.

Middle colic artery: supplies most of the transverse colon.

Inferior mesenteric artery: immediately branches into smaller arteries.

Left colic artery: supplies distal part of the transverse colon and part of the descending colon.

Sigmoid arteries: supply the inferior descending colon and the sigmoid colon.

Blood flow through pelvis Middle artery: supplies each adrenal gland. Middle suprarenal vein: drains each adrenal

gland.Renal artery: supplies each kidney. Renal vein: drains each kidney.Gonadal artery: supplies each gonad.(testes in males and ovaries in females.) Gonadal vein: drains each gonad.

Internal illiac artery: supplies the pelvis and perineum.

Internal illiac vein: drains the pelvis and perineum.

Superior gluteal arteries: supply the gluteal region.

Superior gluteal veins: drain the gluteal region.

Inferior gluteal arteries: supply the gluteal region.

Inferior gluteal veins: drain the gluteal region.

Obturator artery: supplies the medial muscles of the thigh.

Obturator vein: drains the medial muscles of the thigh.

Interpudenal artery: supplies the anal canal and the perineum.

Interpudenal vein: drains the anal canal and the perineum.

Middle rectal artery: supplies the lower portion of the rectum.

Middle rectal vein: drains the lower portion of the rectum.

Uterine and Vaginal arteries: supply the uterus and vagina in females.

Uterine and Vaginal veins: drain the uterus and vagina in females.

Blood flow through the upper limb Subclavian artery: supplies each of the Basilic vein: runs adjacent to the medial

upper limbs. surface of the upper limb drains the dorsal venous network. Superficial vein.

Axillary artery: extends into many branches as it passes the shoulder region.

Cephalic vein: runs alongside the lateral aspect of the upper limb also drains the dorsal venous network. Superficial vein.

Brachial artery: branches into the deep brachial artery and supplies blood to most of the brachial muscles.

Median cubital vein: connects the basilic and cephalic veins and is a common site for venipuncture.

Radial artery: runs along the radius and supplies blood to the forearm and wrist.

Radial veins: run along side the radial artery and drain blood from the palmar arches.

Ulnar artery: runs along the ulna and supplies the forearm and wrist.

Ulnar veins: run alongside the unlar artery and drain the palmar arches.

Superficial palmar arch: formed from the ulnar artery and supplies blood to the palm of the hand.

Brachial veins: travel with the brachial artery and drain the radial and ulnar veins.

Deep palmar arch: formed from the radial artery and supplies the hand.

Axillary vein: brachial and basilic veins merge to form this vein.

Digital arteries: emerge from the arches to supply the fingers.

Subclavian vein: axillary vein is remaned this once it passes the lateral border of the first rib.

Blood flow through the lower limb

Femoral artery: branches to form the deep Great and Small sephenous veins:

femoral artery and supplies the hip joint and many of the thigh muscles.

superficial veins that drain the dorsal venous arch. The great sephenous vein drains into the femoral vein and the small sephenous vein drains into the popliteal vein.

Popliteal artery: supplies the knee joint and the muscles in this region.

Medial and Lateral plantar veins: drain the digital and deep veins of the foot.

Anterior tibial artery: supplies the anterior compartment of the leg.

Posterior tibial veins: drain the medial and lateral plantar veins.

Posterior tibial artery: supplies the posterior compartment of the leg.

Fibular veins: drain the plantar surface of the foot.

Fibular artery: supplies the lateral compartment of the leg.

Anterior tibial veins: drain the deep veins of the ankle and dorsum of the foot.

Medial and Lateral plantar arteries: supply the foot.

Popliteal vein: drains the knee joint and the muscles there.

Digital arteries: supply the toes. Femoral vein: drains the deep veins of the lower leg once they pass the popliteal region.

DevelopmentThere are differences in the fetus circulatory system and that of an average adults. Fetal lungs do not rely on the exchange of gases and oxygenated blood because it is supplied from the umbilical cord attached to the placenta in the mother's womb.

The venous duct is connects the umbilical veins that lead from the placenta to the vena cava of the fetus. Oxygenated blood from the placenta travels into the umbilical veins through the venous duct into the vena cava and mixes with the poorly oxygenated blood of the fetus.

The opening between the Right and left Atria is called the oval opening. It allows blood from both sides of the heart to mix and allows blood to enter pulmonary circulation directly.

The arterial duct is the connection between pulmonary artery and aorta that allow the blood to bypass the the non-functioning lungs of the fetus.

The umbilical arteries and veins are vessels that carry the waste and oxygen from the placenta. The veins are the main oxygen carries to the fetus from the placenta and the arteries are the main waste movers.

Fun Fact

Did you know that if you took the blood vessels out of a child and laid it out in a straight line it would be over 60,000 miles long!

In late-nineteenth-century France there was an individual known as "I'homme prote," or the "protean man." He had exceptional control over all his muscles and could protrude or distort any part of himself at will. He could harden the muscles of his stomach so that if hit with a hammer they would not recoil. He could distend his abdomen to create the appearance of enormous obesity or draw it in until he looked like a living skeleton. According to Quatretages, a celebrated French physician of the time, I'homme prote could shut off all the blood from the right side of his body and control the beating of his heart, feats he credited to his great Muscular Control.

Blood is always red - bright red when it is oxygenated and a darker red when it's lacking oxygen. Deoxygenated blood just **looks** blue because you're seeing it through your skin.

In the News & Case study

This is contrast x-ray taken of the kidneys and the mighty aorta

surgeons use abdominal vein to treat brain artery blockage Prosthetic vein valve shows promise for chronic venous insufficiency Here is a Utah story of a little boy whose femoral artery and vein were cut by shrapnel

from a homemade firework

Glossary

Connections to other body systemsThe cardiovascular system transports gases between the lungs and body cells, while the respiratory system exchanges gases between the atmosphere and blood.

This diagram shows the connection between the cardiovascular system with the lungs.

Without arteries and veins every other system in the body would be affected,they can't work without oxygenReview Questions

1. What disease is most commonly seen in African Americans which affects red blood cells?a. Vasodilationb. Arrhythmia*c.Sickle Celld. Varicose Veins

2. What two arteries arise from the ascending aorta?*a.left & right coronary arteriesb. subclavion & brachiocephalic arteriesc. left & right common carotid arteriesd. left & right axillary arteries

3. Which radiological investigation would you use to asses for deep vein thrombosis?a. Duplex doppler ultrasoundb. Direct venography

c. MRI venography*d. All of the above

4. What is the only artery that carries poorly oxygenated blood?a. Gonadal artery*b. Pulmonary artery c. Right common carotidd. Facial artery