Circulatory System
Two circuits:
Pulmonary circuit – blood travels from heart to lungs back to heart
Systemic circuit – blood travels from heart to body back to heart
Heart and its major vessels:
4 chambers – Right atrium, right ventricle, left atrium, left ventricle
Right atrium:
Pectinate muscles on inner wall surface
Fossa ovales – formerly, foramen ovales inutero
Oxygen poor blood enters right atrium from three vessels - superior vena cava, inferior vena cava and coronary sinus
Superior vena cava
Vein that brings blood from superior region of body
Enters heart at the right atrium
Inferior vena cava
Vein that brings blood from inferior region of body
Enter heart at the right atrium
Coronary Sinus
Vein that brings blood from heart muscles
Collects from coronary veins – great cardiac vein and middle cardiac vein
Opening into right atrium inferiorly to inferior vena cava
Right ventricle:
Oxygen poor blood enters right ventricle from right atrium through flaps
Three flaps form the tricuspid valves (or right atrioventricular (AV) valve)
Chordae tendinae are tendons attached to cusps
Papillary muscles are attached to tendons that help keep cusps in place during ventricular contraction
Ventricular Contraction
Cusps close over AV valves passively from blood pushing on them
Papillary muscles contract, pulling on tendons
Papillary muscles/tendons prevent cusps from swinging wide into atria and allowing back flow of blood
Trabeculae carnae – muscles on ventricle wall that is involved in ventricular contraction
Blood leaves right ventricle to lungs via the Pulmonary Trunk
Pulmonary Trunk:
Oxygen poor blood enters into pulmonary trunk through the pulmonaric semilunar valves
Pulmonary trunk branches into Right and Left Pulmonary artery
Right and left pulmonary arteries take blood to right and left lungs, respectively
Blood becomes oxygen rich
Oxygen rich blood leaves lungs to left atrium via Pulmonary Veins
Left Atrium
Receives oxygen rich blood from pulmonary veins
Lacks pectinate muscles
Left Ventricle
Oxygen rich blood enters left ventricle from left atrium through flaps
Two flaps form the bicuspid valves (aka. Left AV valve or mitral valve)
Chordae tendinae are tendons attached to cusps
Papillary muscles are attached to tendons that help keep cusps in place during ventricular contraction
Works in same fashion as the tricuspid valves
Also contains trabeculae carnae
Blood leaves left ventricle to body via the Aorta
Aorta and its branches:
Ascending aorta
First part of aorta leaving heart
Oxygen rich blood enters ascending aorta through aortic semilunar valves
First branches are right and left coronary arteries that feed heart
Right Coronary arteries
supplies blood to right atrium and portions of ventricles
branches into marginal artery and posterior interventricular artery (blood leaves these areas by the middle cardiac vein to enter coronary sinus and back to right atrium)
Left Coronary arteries
supplies blood to left ventricle and left atrium
branches into circumflex artery and anterior interventricular artery (blood leaves these areas by the great cardiac vein to coronary sinus)
Aortic Arch
Ascending aorta arches and becomes aortic arch
Branches from aortic arch are the brachiocephalic trunk, left common carotid and left subclavian vein
Brachiocephalic trunk, left common carotid and left subclavian all feed the head, neck, shoulders and upper limbs
Left common carotid divides into internal and external carotid arteries feeding the face and cranium, respectively
Brachiocephalic Trunk
- from aortic arch
- right common carotid branches from it
- right common carotid divides into right internal and external carotid arteries
- carotid arteries feeds neck and cranium region
- brachiocephalic trunk is now called right subclavian artery
Right Subclavian arteries
- from brachiocephalic trunk
- thyrocervical trunk provides blood to neck, shoulder and upper back
- internal thoracic artery provides blood to rib cage
- vertebral artery provides blood to brain and spinal cord
- right subclavian artery passes under clavicle and is called right axillary artery
- right axillary artery descends right upper arm and becomes right brachial artery (around the area that T. major inserts on humerus)
right brachial artery divides into the radial and ulnar arteries
right axillary, brachial, radial and ulnar arteries provide blood to the right upper arm, forearm, and hand
Left common carotid
from aortic arch
divides into the left internal and external carotid arteries
feeds neck and head region
Left subclavian arteries
from aortic arch
left thyrocervical trunk, internal thoracic artery and vertebral artery provides blood to the left side of the body (same body parts as right side)
left subclavian artery passes under clavicle and is called left axillary artery
left axillary artery descends left upper arm and becomes left brachial artery
left brachial artery branches into radial and ulnar arteries
Descending Aorta
- divided by the diaphragm into abdominal and thoracic descending aorta
Unpaired:
celiac trunk
divides into the left gastric artery, splenic artery, and common hepatic artery
left gastric artery feeds stomach
splenic artery feeds the spleen
common hepatic artery feeds liver
superior mesenteric artery
inferior to celiac branching
feeds pancreas, duodenum, small intestine and large intestine
inferior mesentery artery
inferior to superior mesenteric branching
delivers blood to portions of large intestine and rectum
Paired arteries:
renal arteries
close to superior mesenteric artery
right and left renal arteries
feed right and left kidneys
Gonadal arteries
between superior mesenteric and inferior mesenteric arteries
right and left gonadal arteries
feed gonads (testes in males and ovaries in females)
in males, called testicular arteries
in females, called ovarian arteries
Common iliac arteries
termination of descending aorta
right and left common iliac arteries
feed pelvic region and upper thigh
branches of common iliac arteries:
internal and external iliac arteries
internal iliac arteries supply blood to pelvic, urinary bladder, external genitalia, and medial side of thigh
external iliac artery becomes femoral artery as is descends down anterior thigh region
branches of femoral artery:
femoral artery branches from femoral artery and supplies blood to deep muscles of thigh
deep femoral artery passes through adductor magnus muscle (adductor hiatus) and becomes posterior
changes name on posterior side to popliteal artery
branches of popliteal artery:
branches into the posterior tibial artery and anterior tibial artery
posterior tibial artery has a branch that runs along fibula bone on posterior side and is called fibular artery
anterior tibial artery travels between tibia and fibula to become anterior
branches of popliteal arteries provide blood to skin and muscles of anterior and posterior portion of leg
INUTERO BYPASSES (in embryo):
To divert more blood to placenta for oxygen (instead of lungs)
Foramen ovales – hole between right and left atria; at birth becomes fossa ovales
ductus arteriosus – canal between pulmonary trunk and aorta; at birth becomes ligamentum arteriosum
Blood returning to heart via veins:
Veins of the lower leg, anterior thigh and pelvic region
* each of these have a right and left side
Great saphenous vein – longest vein in body and returns blood from leg region
anterior tibial vein – goes between tibia and fibula to branch into posterior tibial vein; brings blood from anterior lower leg
posterior tibial vein – drains blood from posterior lower leg; becomes popliteal vein when coursing in popliteal region (posterior side)
popliteal vein – travels through adductor hiatus and becomes deep femoral vein (anterior thigh region)
Deep femoral vein – drains into femoral vein on anterior side
Great saphenous vein – drains into femoral vein on anterior side
Femoral vein – receives blood from great saphenous vein and deep femoral vein; located in thigh region; drains into the external iliac veins
External Iliac veins – femoral vein becomes external iliac veins in pelvic region
Internal Iliac veins – drain into external iliac veins to become common iliac veins
Common Iliac veins – internal iliac veins joins external iliac veins and becomes common iliac vein; right and left side join together to drain into inferior vena cava
Inferior Vena Cava – Common Iliac veins from right and left lower limb form together and begin the inferior Vena Cava
Tributaries entering Inferior Vena Cava:
Common iliac veins- base of inferior vena cava, draining from thigh and pelvis
Renal veins – draining from kidneys
Gonadal veins – draining from gonads
Hepatic veins – draining from liver
**Veins do not drain directly from digestive tract (eg. intestines, stomach) – they go through liver first via hepatic portal vein and then enter IVC via hepatic veins**
Tributaries entering Superior Vena Cava:
External jugular – drains blood from face region
Internal jugular – returns blood from cranium
Subclavian vein – returns blood from arm and shoulder region
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