Introduction to the Circulatory System Flashcards
Circulatory system:
made up of the cardiovascular system and the lymphatic system
Cardiovascular system:
made up of the arterial system, the heart, and the venous system
Pulmonary circulation:
right side of heart → lungs → left side of heart
Systemic circulation:
left side of heart → capillary beds of organs and tissues → right side of heart
Epicardium
(external): visceral serous pericardium
Myocardium(middle):
cardiac muscle layer
Endocardium(internal):
continuous with endothelium of blood vessels connecting with the heart
Conduction system of the heart
- Electrical impulse starts at SA node - atria contract
- Impulse travels to AV node at AV septum
- Impulse travels down left and right bundles in the IV septum
- Impulse spreads out to myocardium through conducting fibers - ventricles contract
the arterial system
Each artery (and its branches) carries oxygenated blood to a territory
Tunica intima(internal):
endothelium
Tunica media(middle):
smooth muscles and elastic fibres
Tunica adventitia(external):
connective tissue
Sympathetic tone:
background, low level contraction of smooth muscle in arterioles
- Due to tonic production of action potentials to arterioles by sympathetic nerves
Anastomoses
where arteries connect to each other without an intervening capillary network
End artery:
the only arterial blood supply to a given area of the body
infarction:
irreversible cell death due to hypoxia caused by loss of arterial bloody supply
Left and right coronary arteries supply blood to
heart muscle
Branches of the arch of the aorta supply blood to
the upper limbs and head
Descending aorta supplies
thorax and abdomen
Within the abdomen, the abdominal aorta branches into the two common iliac arteries that provide blood to
the pelvis and lower limbs
Veins drain
deoxygenated blood from a territory
Venous blood is ‘pumped’ back towards the heart by:
- Venous valves
- Skeletal muscle pump
- Accompanying veins
Superficial veins:
smaller, run within the superficial fascia, drain into deep veins
Deep veins:
larger, run deep to the deep fascia in cavities, often in neurovascular bundles
Hepatic portal venous system:
drains venous blood from absorptive parts of the GI tract and associated organs for cleaning
Systemic venous system:
drains venous blood from all of the organs and tissues into the superior or inferior vena cavae
Lymphatic capillaries
collect tissue fluid (lymph)
Lymphatics carry lymph through
lymph nodes
Eventually lymph is returned into
the central veins in the root of the neck
Lymph from superficial lymphatics →
deep lymphatics
Lymph from right lymphatic duct →
right venous angle
Lymph from thoracic duct →
left venous angle
