Cardiovascular System

Part II

Blood Vessels Vascular system:

A closed transport system where blood circulates through the blood vessels

Arteries: Blood enters from the heart into the circulatory system from

these and moves into the … Arterioles:

Smaller branches off the arteries which feed into the.. Capillaries:

Contained within the tissues and branch out becoming smaller and smaller. The only connection between arteries and veins. Serves the needs of the body’s cells by exchanging blood between tissue cells and blood.

Venules: Smaller branches off the veins. Drain from the capillaries and

enter into the … Veins:

Empty blood from the circulatory system back into the heart.

Blood Vessels Blood Vessel Walls:

Contain three layers/walls called “Tunics” Tunica Intima:

Lines the interior of the vessels and is a thin layer of endothelial tissue on top of a thin layer of loose connective tissue. It has a slick surface to decrease friction as blood flows through it.

Tunica Media: Bulky middle “coat” made of smooth muscle and elastic

tissue. The smooth muscle is controlled by the Sympathetic NS and is active in changing the diameter of the vessels and in bringing BP up or down

Tunica Externa: Outermost layer made up of fibrous connective tissue.

It functions to support and protect the vessels.

Artery Walls and Functions

Much thicker than veinsMust be able to expand as the blood is

forced into them and then recoil as the blood moves out.

Walls must be strong and stretchy in order to accomplish these goals

Vein Walls and Function

Thinner walls located further from the heart

Pressure in veins is continually lowThey contain valves which prevent

backflowVeins are modified to make sure the blood

returning to the heart is the same amount as blood being pumped out of the heart.

Skeletal Muscle Activity and Venous Return

The action of muscle movement enhances venous return by contracting and relaxing causing the blood in the veins to move towards the heart.

Respiratory Pump

When we inhale pressure in the thorax decreases causing the veins near the heart to expand and fill with blood.

Major Arteries and Systemic Circulation

Aorta: Largest artery of the body. Parts of the aorta are named for their

location and/or shape Ascending Aorta: curves upward from the left

ventricle and when it arches to the left it becomes the aortic arch.

• Right and Left Coronary Arteries: Only branches of the ascending aorta and

serve the heart.

Major Arteries and Systemic Circulation

Aortic Arch: Brachiocephalic Artery: first branch of the

aortic arch which splits into… Right common carotid artery: serves the brain,

skin and muscles of the neck Right Subclavian Artery: serves part of the brain

and right arm Left Common carotid Artery: second branch

off the aortic arch which splits into … Left internal carotid: serves the brain Left External carotid: serves the skin and muscles

of the head and neck.

Major Arteries and Systemic Circulation

Left Subclavian Artery: third branch of aortic arch Vertebral Artery: serves part of the brain Axillary Artery: serves the axilla Brachial Artery: serves the arm Radial and Ulnar arteries: serves the forearm

Major Arteries and Systemic Circulation

Thoracic Aorta: moves downward through the thorax following the spine Intercostal arteries: 10 pairs serving the ribs Bronchial arteries: serve bronchioles of lungs Esophageal Arteries: serve esophagus Phrenic arteries: serve diaphragm

Major Arteries and Systemic Circulation

Abdominal Aorta: moves through diaphragm into the abdominopelvic cavity. Celiac Trunk:

Left gastric artery: supplies the stomach Splenic Artery: serve the spleen Common hepatic artery: serves part of colon

Superior Mesentrick artery: supplies most of the smaller intestine and the first part of the large.

Renal Arteries: serve the kidneys Gonadal Arteries:

Ovarian: serve ovaries in females Testicular: serve testes in males

Major Arteries and Systemic Circulation

Lumbar arteries: pairs of arteries which serve the muscles of the abdomen and trunk.

Inferior mesentric artery: serves second half of the large intestine.

Common Iliac Arteries: final branches of the abdominal aorta. Internal iliac artery: supplies pelvic organs External iliac artery: enters the thigh and becomes… Femoral artery: serves thigh and becomes … Popliteal artery: splits into … Anterior and Posterior tibial arteries: supply leg and

foot Dorsalis Pedis artery: supplies bottom of foot

Major veins of Systemic circulation

Superior Vena cava: veins coming from the head and armpits Radial & Ulnar Veins: deep veins draining the forearm

and they come together to form the: Brachial Vein: drains the arm Axillary vein: drains the axillary region

Cephalic Vein: superficial drainage of the lateral arm & empties into the axillary vein

Basilic Vein: Superficial vein drains the medial aspect of the arm and empties into the brachial vein

Medial Cubital vein: the joining of the cephalic and basilic veins. Major site of blood draws

Major veins of Systemic circulation

Subclavian vein: receives blood from the axillary vein, skin and muscles of head through the jugular vein.

Vertebral vein: drains posterior headInternal Jugular vein: drains dural sinuses of

brainBrachiocephalic veins: right and left drain from

the subclavian, vertebral and internal jugular veins. The join to form the … Superior vena cava: where blood enters the heart

Major veins of Systemic circulation

Azygos vein: single vein draining the thorax and enters into the superior vena cava

Inferior Vena cava: veins draining from the lower body Anterior and Posterior tibial veins: drain the calf and

foot. Peroneal vein: drains the calf and foot Popliteal vein: posterior tibial vein that becomes Femoral vein: drains the thigh and becomes the External Iliac vein: where blood drains from the pelvis

Major veins of Systemic circulation

Great Saphenous vein: longest veins in the body. Receives drainage from the leg. Begins at the foot and goes to the thigh.

Common iliac vein: right and left are formed by the external and internal iliac veins and drain the pelvis

Right gonadal vein: drain the right ovary and right testicle

Left gonadal vein: drain the left ovary and left testicle.

Major veins of Systemic circulation

Renal Veins: drain the kidneysHepatic portal vein: single vein which

drains the digestive tract organsHepatic veins: drain the liver

Arterial Supply of the Brain

The brain is supplied by two pairs of arteries Internal carotid:

Run through the neck and enter the skull through the temporal bone and then divide into the…

• Anterior and Middle cerebral arteries: supply most of cerebrum

Vertebral artery: Paired arteries running upward from the subclavian arteries

at the base of the neck. In the skull they join to form the …• Basilar arteries: serve the brain stem and cerebellum. At the

base of the cerebellum they divide into the … Posterior Cerebral Arteries: supply the posterior cerebrum

Circle Of Willis

The circle of Willis is where the anterior and posterior blood supplies unite by small communicating arterial branches.

They form a complete circle around the base of the brain of connecting blood vessels.

Hepatic Portal Circulation

Veins of hepatic circulation drain the digestive system, the spleen and pancreas and deliver blood to the liver through… Hepatic portal vein: blood contained here contains

large amounts of nutrients and ensures that the liver processes these nutrients before entering systemic circulation.

Inferior mesentric vein: drains part of the large intestine and drains into the …

Splenic vein: drains the spleen, pancreas and left side of the stomach

Hepatic Portal Circulation

Superior Mesentric vein: joins with the splenic vein to form the hepatic portal vein

Left gastric vein: drains the right side of the stomach directly into the hepatic portal vein.

Fetal CirculationIn the fetus the lungs and digestive system are

not functioning so all nutrients and gas exchange go through the placenta. Umbilical cord: contains three blood vessels

Umbilical vein: one vein carries blood rich in nutrients and oxygen to the fetus

Umbilical arteries: two arteries carrying carbon dioxide and debris from the fetus to the placenta

Ductus Venousus: bypass for blood to go towards the heart and bypass the liver which is non functioning.

Fetal Lungs

In the fetus the lungs are non-functional and are collapsed. Shunts: there are two shunts which make sure the

lungs are bypassed. Foramen Ovale: blood entering the right atrium is

shunted directly to the left atrium through this opening in the internal septum. It closes after birth

Ductus Arteriosus: short vessel connecting the aorta and pulmonary trunk. At birth it collapses and becomes the …

Ligamentum Arteriosum: fibrous tissue completing the circulatory system of an adult.