Circulatory System: Blood Vessels

Transport blood from the heart HIGH pressure Arteries Transport blood from the heart HIGH pressure Carry oxygen rich blood (except pulmonary artery)

3 tunics (layers): Tunic intima – friction reducing lining endothelium Tunic media – bulky middle layer muscle and elastic tissue Tunic externa – connective tissue

Veins Transport blood back to the heart LOW pressure Same 3 layers except thinner walls Valves = blood flow in one direction

Capillaries One thin layer of endothelium Play an exchange role with tissue cells for nutrients and waste Capillary beds open and close to shunt blood from one body system to another Pressure drops Lumen is the opening

Pulse Pulse is the alternate expansion and recoil of a blood vessel wall as the heart beats; felt over any external superficial artery = pressure point

Blood Pressure Blood pressure is the pressure that blood exerts on the walls of the blood vessels Forces blood to continue moving

Pressure is measured over a pressure point, both systolic and diastolic

Arterial blood pressure is influenced by heart rate (higher = higher) or resistance to blood flow: decrease in diameter, stretch of vessels, or viscosity of blood

Special Circulations

Hepatic Portal The hepatic portal veins drain the digestive organs, spleen, pancreas, and deliver nutrient rich blood to the liver – which is involved in maintaining the proper glucose, fat, and protein concentrations.

Brain Circulation A continuous blood supply is maintained by two pairs of arteries: The internal carotids The vertebral arteries

The Internal Carotids each divide and run into the anterior and middle cerebral arteries Vertebrals each divide to form the posterior cerebral arteries

The anterior and posterior blood supply are connected by branches- forming a complete circle

The Circle of Willis It protects the brain by supplying more than one route to reach all brain tissue

Fetal Circulation A temporary circulation involving 3 vessels: One umbilical- nutrients and oxygen to the fetus two umbilical arteries- carry carbon dioxide and waste to the placenta Shunts bypass the lungs and the liver

Naming the systemic Arteries and Veins Starting with the arteries we will move away from the heart (arteries move blood away)

Arteries above the diaphragm All branch off the Aorta (largest artery) 1st SMALL branch is the coronary artery- which serves the heart 1st Large branch is the Brachiocephalic 2nd Large branch is the Right Common Carotid 3rd Large branch is the Right Subclavian

Off of the Brachiocephalic: Left Common Carotid Left Subclavian

Each of the Common Carotids branch into : Internal Carotid which goes to the brain External Carotid which serves the head

Each of the Subclavians will: 1st branch will be Vertebral which goes to the brain Under the armpit the subclavian becomes the Axillary Which in the upper arm is the Brachial where blood pressure is normally taken The Brachial will split into the Ulnar (medial) and the Radial (lateral)

Arteries under the diaphragm All branch off the Aorta (abdominal) 1st branch is the Celiac Trunk with 3 branches: Gastric- to stomach Hepatic- to liver Splenic- to spleen Next comes the Superior Mesenteric which serves the upper part of the intestine

Continuing down the abdominal aorta: Right and Left Renal brings blood to the kidneys Lumbar brings blood to the back muscles Gonadal brings blood to the gonads At the end of the torso: Common Iliac Artery

The Common Iliac Artery splits: External Iliac which becomes the Femoral in the thigh Internal Iliac loops back towards the pelvis Deep Femoral goes toward buttocks Femoral continues down thigh, will become the Popliteal behind the knee It splits into the Anterior and Posterior Tibial Ends in the foot at the Dorsalis Pedis

The veins bring blood back to the heart so we start at the distal end and move towards the heart.

All the veins above the diaphragm drain into the Superior Vena Cava The Radial and Ulnar Veins from the forearm drain into the Brachial vein The Cephalic (lateral) and Basilic (medial) meet at the Median Cubital (place where you get blood drawn for blood tests!) They all drain into the Brachial vein

The Brachial drains into the Axillary under the armpit The Axillary drains into the Subclavian The Vertebral takes blood from the posterior head and drains into the Subclavians The right and left Subclavians drain into the right and left Brachiocephalic

The External Jugular drains the head and the Internal Jugular drains the brain: both empty into the Braciocephalic The Right and Left Braciocephalic join to form the Superior Vena Cava which enters the heart The Azygos is a single vein that runs up the spine, drains the entire thorax and enters the SVC just before the heart

All veins below the diaphragm drain into the Inferior Vena Cava The Anterior and Posterior Tibial – drain the calf and foot then become the Popliteal at the knee The Popliteal becomes the Femoral at the thigh The Great Saphenous vein is the longest vein, it drains the superficial veins of the leg and empties into the Femoral

The Femoral drains into the External Iliac The Internal Iliac drains the pelvis The External & Internal Iliacs meet at the Common Iliac The Right and Left Common Iliac join to form the Inferior Vena Cava

The Renal veins drain the kidneys The Gonadal veins drain the gonads The Hepatic Veins drain the liver They all drain into the Inferior Vena Cava REMEMBER ALL DIGESTIVE ORGANS (GASTRIC, INTESTINES) DRAIN INTO THE HEPATIC PORTAL AND GO TO THE LIVER FOR PROCESSING, THEN ARE DRAINED BY THE HEPATIC VEIN!

The Inferior Vena Cava enters the heart, and it starts all over again.