SA node
starts the heart beat
Automatic
Sends stimulus that causes both atria to contract at the same time
What pacemakers do
AV node
Close to coronary sinus
Between atria and ventricles
Right & left sides are bundled up and branch out over each ventricle
Purkinje fibers transmit the impulse that cause the ventricles to contract at the same time
Contractions start at the apex and travel to the base
Blood Vessels
3 Layers in a vessel
called tunics
Tunica Interna
Thin surface layer of endothelium & elastic CT
Tunica Media
Smooth muscle with some elastic CT
Circular arrangement
Contractions constrict flow of blood, increasing Blood Pressure (BP)
Relaxing dilates the vessels decreasing BP
Tunica Externa
Thin white fibrous elastic CT
Ellastic Arteries
Conducting Vessels
Aorta is an example
Expand and recoil
Delivers to muscular arteries
Musclar arteries
Conduct blood to location or distribute
Continuous flow
Autoregulation
Automatic local adjustment of blood flow in a given region of the body in
response to needs of over tissues à need for oxygen is stimulus
Colateral Circulation
2 arteries serving the same location
Anastomosis
2 arteries joining at distal end
Infarction
Death of cell due to lack of oxygen
NO VALVES IN ARTERIES
Capillaries
Layer of simple squamous epithelium
Slows the flow of blood
Purpose of the cardiovascular system is to serve these
More numerous in tissues that need/use more oxygen
Can be closed of with sphincters
Interconnector between arterioles and venules
Veins
3 layers
Same as arteries but less distinct
Minimal elastic tissue
Thinner walls
Greater diameter
Vena comitans
2 veins following a common artery
Surface veins
Cutaneous
Valves are use to carry blood up against the force of gravity
Low Pressure
Pressure gradients help move blood
Skeletal muscles can act as a pump
Respiratory can act as a pump
Pulmonary Circuit
Receives oxygen deficient blood
Purpose is to oxygenate blood
Begins Right Ventricle
Conus arteriosus
Ends in the Left Atrium
Pulmonary trunk
In front of ascending aorta
To the left & under the arch
Short wide vessel
Is an Artery
Divides into right and left arteries
Right side delivers blood to right side of lung
Branches in lower and superiors branches
Lower branch is larger and delivers to lower lobes
Superior branch delivers to upper lobe
Left side delivers blood to left side of lung
Branches into lower and superior
Lower branch delivers to lower lobe
Superior branch delivers to upper lobe
2 Pulmonary veins from each lung empty into left atrium
Systemic Circuit
More extensive
Starts in Left ventricle
Ends in right atrium
Dispenses from Aorta
Delivers Oxygen to all systemic arteries
Aorta has 3 regions
Ascending
Arch
Descending (2 parts)
Thorassic
Abdominal
Ascending Aorta
2 coronary arteries
only branches of ascending Aorta
Right side receives first
Left side divides more
Anterior ventricular artery
Posterior ventricular artery
Circumflex artery
Arch of the Aorta
Region that leaves the pericardial sac
Leave out & heads back
Ends ~ T4
3 branches on the top of the arch
1st and largest is Brachiocephalic
Left Common Carotid 2nd
Left Subclavian 3rd
Descending Aorta
Begins ~ T4 ~ T6
Thorassic branch
Has parietal & visceral branches
Abdomincal branch
Has parietal & visceral & terminal branches
Systemic veins
Drainage system of blood
Lots of valves to prevent backflow of blood
Brings back nutrients waste and lacks oxygens
Tributaries instead of branches
Tributaries of origin
2 veins merging into 1 common vein
Superficial
Under skin
No companion arteries
Empty into deep veins
Deep
Travel with artery
Artery usually has the same name
Venus Sinus
Space between layer of dura mater (outer layer)
Endothelium lined
Empty into internal jugular vein
Coronay Sinus
Heart wall return
Superior Vena Cava à SVC
7cm long
Receives blood from right and left brachiocephalic
Right side is shorter
Receives blood from head neck thorax and upper extremities
Inferior Vena Cava à IVC
Recieves blood from trunk and lower limbs
All 3 empty into Right Atrium
Portal Sytems or Hephatic (Liver) system
Artery
Arteriole
Capillary (sinusoid)
Venule
Capillary (sinusoid)
Venule
Vein
Recieves blood from digestive tract and spleen
Portal vein takes blood to liver
Feeds capillary beds
Which filter the blood
What gets filtered depends on what the body needs at the moment
Fetal Circulation
5th week the fetal heart can start beating
Foramen Ovale
Oval shaped hole between right and left atrium
Allows blood to skip going to the lungs since a baby doesn’t use it lungs
Decreases in size after birth
Becomes fossa ovale
Large Eustachian valve in IVC
Prevents blood from going into ventricle prematurely
Ductus Arteriosus
Allows blood in right ventricle to skip lung
Becomes ligamentum arteriosum
2 umbilical arteries
lack oxygen
goes to placenta to be oxygenated and get nutrients
becomes lateral umbilical ligament
1 umbilical vein
goes back to liver/IVC
becomes ligamentum teres
Ductus venosus
Between umbilical vein & IVC
Skips liver
Becomes ligamentum venosum
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