Cardiovascular 4 Flashcards
Describe fetal circulation
Pulmonary system is inactive in the fetus
-Blood is oxygenated maternally
- Blood is shunted from the pulmonary to systemic circulation by two ways
- foramen ovale
- ductus arterioles
Shunting allows for by-passing the pulmonary circulation
The ductus venosus shunts less than a third of the blood flow of the umbilical vein directly to the inferior vena cava
-Allows oxygenated blood from the placenta to bypass the liver
What happens to pulmonary circulation after birth?
Closure of the ductus arteriosus and foramen ovale completes the transition of fetal circulation to newborn circulation
-Ductus venosus becomes Ligamentum Venosum
- Ductus Arteriosus becomes Ligamentum Arteriosum - Foramen ovale becomes foramen ovalis
Summarize the divisions of the circulatory system
Human circulation can be divided into
- Pulmonary circulation
- Systemic circulation
Both are closed circuits
The two circuits are arranged in series
The output of one becomes the input of the other
Summarize pulmonary circulation
Is the movement of blood from the heart to the lungs and back to the heart again
-This type of circulation adds oxygen and removes carbon dioxide from the blood
Summarize systemic circulation
- Is the circulation of blood between the heart and the body
- Brings blood to and from the cells
Contains:
-Coronary circulation: supplies blood directly to the heart muscle
- Hepatic-portal circulation
- Cerebral circulation
Summarize hepatic circulation
- Tributaries from portions of stomach, pancreas, and large intestine lead into the splenic vein
- Tributaries from small intestine and portions of large intestine, stomach, and pancreas leads into the superior mesentric vein
- Superior mesentric vein leads into hepatic portal vein, while the splenic vein leads into the hepatic portal vein as well
- Hepatic portal vein—> liver—> hepatic vein—> inferior vena cava—> heart—> abdominal aorta—> proper hepatic artery—> liver
Summarize cerebral circulation
Movement of blood through the network of blood vessels supplying the brain
The brain accounts for about 2% of the body weight
- Receives 17% of the cardiac output
- Consumes about 20% of the entire oxygen used by the body
- 10 seconds of interruption in blood flow leads to to unconsciousness
Describe the aorta and its branches
The aorta is usually divided into 4 sections:
-Ascending aorta (between the heart and the aortic notch)
- Aortic arch
- descending aorta: this is divided into
- Thiracic Aorta (above the diaphragm)
- Abdominal aorta (extends from below the diaphragm to the common iliac arteries)
Describe the arterial supply of the lower limb
The major arterial supply to the lower limb is the femoral artery
- Continuation of the external iliac artery beyond the inguinal ligament
- Branches supply most of the thigh, all of the leg and foot
- Other arteries supplying parts of the lower limb are:
- Superior gluteal
- Inferior gluteal
- Obturator
Describe the major veinous drainage of the lower limb
Divided into two groups
-Superficial: originate from the dorsal venous arch in the foot
- Great Saphenous vein
- Small Saphenous vein
- Deep: generally follow the arteries
The major deep vein draining the lower limb is the femoral vein
-Becomes the external iliac vein when it passes underneath the inguinal ligament to enter the abdomen
Describe the veinous drainage of the major systemic veins
The major systemic veins are:
Superior vena cava
-carries de-oxygenated blood from the upper half of the body to the right atrium
-Formed by the right and left brachiocephalic veins
-The azygos vein joins it just before it enters the right atrium
Inferior vena cava
- Carries de-oxygenated blood from the lower half of the body into the right atrium
- Formed by the union of the left and right common iliac veins
- Anastomoses with the azygos vein system (which runs on the right side of the vertebral column) and venous plexuses next to the spinal cord
Explain what is the azygos system of veins
The azygos vein on the right
- The hemiazygos vein vein and the accessory hemiazygos vein, on the left
- Serves as an important anastomotic pathway capable of returning venous blood from the lower part of the body to the heart if the inferior vena cava is blocked
