Circulation
Cardiovascular System = Heart, Blood and Vessels
Lymphatic System = Lymph nodes, Organs and Vessels
The Lymphatic Vessels
• Function: to collect excess tissue fluid collecting at
arteriole end of capillary beds, and return leaked blood
proteins to blood (maintain osmotic pressure needed to
take up water into bloodstream)
• Lymph is moved through vessels
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Pulse of nearby arteries
Contraction of surrounding skeletal muscle
Regular movement of body (wiggling legs)
Muscle in Tunica Media
Lymphatic System…The Players:
• Lymph- clear fluid from loose CT at capillaries
– Contains small molecules of blood plasma, water, various
ions, nutrient molecules, respiratory gases
• Lymphatic capillaries (near blood capillaries) 
• Lymph collecting vessels (small, 3 tunicas, #
valves)
• Lymph nodes (sit along collecting vessels)-clean
lymph of pathogens, they are NOT glands
• Lymphatic trunks (convergence large collecting
vessels)
• Lymphatic ducts  empty into veins of neck
Lymphatic Ducts
• Thoracic Duct
– Receives lymph from large trunks in abdomen and
thorax
– Receives lymph from ducts of thoracic lymph nodes
– Along vertebral bodies
– Contain valves to ensure 1-way flow of lymph to lymph
nodes
– Drains into left Brachiocephalic Vein (or subclavian or
int. jugular veins)
pg 154
Functions of Heart and Cardiovascular
System
• Cardiovascular System
– Bulk flow of blood
– Exchange with tissue
• Heart
– Right side receives oxygen-poor blood from body
tissues and pumps the blood to the lungs
– Left side receives the oxygenated blood from the
lungs and pumps the blood throughout the body
Location of Heart in Chest
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Oblique Position
Apex = Left of Midline (5th ICS), Anterior to rest of heart
Base (posterior surface) sits on vertebral column
Superior Right = 3rd Costal Cartilage, 1” right midsternum
Superior Left = 2nd Costal Cartilage, 1” left midsternum
Inferior Right = 6th Costal Cartilage, 1” right midsternum
Inferior Left = 5th Intercostal Space at Midclavicular line
Pg 178
Cardiac
Conduction
• Intrinsic system initiating and
coordinating contraction of heart
muscle
– Sinoatrial node (where SVC enters RA)
– Atrioventricular node (in atrioventricular
septum)
– AV Bundle (in IV septum then splits)
– Purkinje fibers (throughout LV)
• Cardiac Plexus (external innervation)
– Vagus (parasympathetic)
– Sympathetic trunk
pg 201
Blood Flow to Supply the Heart Muscle
• Heart wall too thick for diffusion of nutrients
• Rt and Lft Coronary Arteries
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Branch from Ascending Aorta
Have multiple branches along heart
Sit in Coronary Sulcus
Coronary Heart Disease
• Cardiac Veins
– Coronary Sinus (largest)
– Many branches feed into sinus
– Sits in Coronary Sulcus
pg 193
Pericardium
pg 177
• Pericardium (3 layers)
• 1) Outer-fibrous pericardium
– Serous pericardium
• 2) parietal
• 3) visceral (epicardium)
• Pericardial Cavity
– between layers of serous pericardium
– serous fluid
– lubricate heart while beating
External Features of Heart
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Pg 181
Interventricular sulcus
Coronal/Coronary sulcus
Auricles of atria
Apex
Base
Coronary vessels
Ligamentum Arteriosum
The Great Vessels and major branches
Aorta (from Left Ventricle)
• Ascending
– Coronary arteries
• Aortic Arch
– Brachiocephalic trunk
– Left Common Carotid
– Left Subclavian
• Descending (Thoracic/Abdominal)
– Many small branches to organs
Pulmonary Trunk (from Rt Ventricle)
- -2 Pulmonary Arteries into lungs
Inferior/Superior Vena Cava
- Coronary sinus
Pg 203
Layers of Heart
• Epicardium
(most superficial)
– Visceral serosa
• Myocardium (middle layer)
– Cardiac muscle
– Contracts
• Endocardium (inner layer = lining)
Pg 190
– Endothelium on CT
– Lines the heart
– Creates the valves
Fibrous Skeleton of Heart
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Insertion for cardiac muscle
Anchors valve cusps
Prevents valves from opening too much
Block electrical impulses from atria to
ventricles
• Contains AV node
Pg 192
Heart Chambers
• 2 receiving chambers:
– Right atria
– Left atria
• 2 pumping chambers:
– Right ventricle
– Left ventricle
• Atria are superior to ventricles
• Arrangement is not linear…it’s twisted!
Right Heart Chambers: Pulmonary Pump
• Right Atrium (forms most of base of heart)
pg 186, 188
– Receives O2-poor blood from body via IVC, SVC, Coronary sinus
– Ventral wall (w/Pectinate muscles) and dorsal wall (no pectinate muscles)
separated by crista terminalis
– Fossa Ovalis- on interatrial septum, remnant of Foramen Ovale
• Right Ventricle
– Receives O2-poor blood from right atrium through tricuspid valve
– Trabeculae Carnae- muscle ridges along ventral surface
– Chordae Tendinae-fibrous cords running between AV valve cusps and papillary
muscles
– Papillary Muscles (3)-cone-shaped muscles within ventricles to which chordae
tendinae are anchored
– Moderator Band (septomarginal trabecula)-muscular band connecting anterior
papillary muscle to interventricular septum
– Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk
Left Heart Chambers: Systemic Pump
• Left Atrium
– Receives O2-rich blood from 4 Pulmonary Veins
– Pectinate Muscles line only auricle
• Left Ventricle (forms apex of heart)
– Receives blood from Left Atrium via bicuspid valve
– Same structures as Rt Ventricle: Trabeculae carnae,
Papillary muscles (2), Chordae tendinae
– No Moderator band
– Pumps blood into aorta via Aortic Semilunar Valve to
body
pg 189, 190
Heart Valves: Lub*-Dub**
• *Tricuspid Valve: Right AV valve
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3 Cusps (flaps) made of endocardium and CT
Cusps anchored in Rt. Ventricle by Chordae Tendinae
Chordae Tendinae prevent inversion of cusps into atrium
Flow of blood pushes cusps open
When ventricle is in diastole (relaxed), cusps hang limp in ventricle
Ventricular contraction increases pressure and forces cusps
closed
• *Bicuspid (Mitral) Valve: Left AV valve
– 2 cusps anchored in Left Ventricle by chordae tendinae
– Functions same as Rt. AV valve
• They close together
pg 188
Semilunar Valves (the dub)
pg 191
• Semilunar valves: prevents backflow in
large arteries
• Pulmonary Semilunar Valve
– Right Ventricle and Pulmonary Trunk
• Aortic Semilunar Valve
– Left Ventricle and Aorta
• Made of 3 Cusps
– As blood rushes past the cusps are flattened
– As it settles they’re pushed down (valve closed)
Flow of Blood
• O2-poor blood (S+I VC, Coronary Sinus) enters Rt Atrium
• Travels through Tricuspid Valve into Rt Ventricle
• Pumped out through Pulmonary Semilunar Valve into
Pulmonary trunk (branches into Pulmonary Arteries) and to
lungs
• After circulating through lungs, O2-rich blood returns to the
heart through 4 Pulmonary veins
• The O2-rich blood enters the Left Atrium
• Travels through Bicuspid/Mitral Valve into Left Ventricle
• Pumped out through Aortic Semilunar Valve into Aorta to
be distributed to rest of body by descending aorta and
branches of aortic arch
Cardiovascular Flow of Blood
• HeartArteries(conducting-distributing)
ArteriolesCapillaries of tissues
• At Capillaries O2 is delivered and CO2 picked
up
• CapillariesVenulesVeinsHeart
Circuits
• Pulmonary Circuit
– Vessels carrying blood to and from lungs
– Pulmonary arteries and veins
• Systemic Circuit
– Vessels carrying blood to and from the rest of the
body
– All other vessels
pg 185
Blood Vessels
• Powered by the heart!
• Carry blood to and from the heart
• 3 main types:
– Arteries
• Carry blood away from heart
• arterioles
– Capillaries
– Veins
• Carry blood toward heart
• Venules
• Tunica externa
– Outermost layer
– CT w/elastin and collagen
– Vaso Vasorum
• Tiny arteries, veins, capillaries on vessels to
nourish them (outer half)
Anatomy of
Arteries and
Veins
– Protects, Strengthens, Anchors
• Tunica media
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Middle layer
Circular Smooth Muscle
Collagen & Elastic Fibers
Vaso-constriction/dilation
• Tunica intima
– Innermost layer
– Endothelium
– Minimize friction
www.histology-world.com/keyfeatures/vessels1.htm
Vessels of Cardiovascular System:
Arteries
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Carry blood AWAY from heart
Systemic Circuit: carry O2 blood
Pulmonary Circuit: carry de-O2 blood
Walls thicker than Veins
– Tunica media > Tunica externa
• 3 Types
– Conducting (elastic)
• large, elastin, high pressure
– Distributing (muscular)
• medium size, to organs
– Arterioles
• smallest
Capillaries
• Smallest blood vessels
• Lumen is typically only 1 RBC thick
• Only 1 endothelial cell layer surrounded by basal lamina
(no tunica media or externa)
• Deliver O2 and nutrients to cells and remove waste
• Capillary Beds: networks of capillaries
– Regulating amount of blood going to cells throughout tissues
– Supply tissues and organs that otherwise have poor capillary
circulation
• Epithelium, cartilage has no capillaries
Vessels of Cardiovascular System:
Veins
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Carry blood from capillaries INTO the heart
Systemic Circuit: O2 poor blood
Pulmonary Circuit: O2 –rich blood
Pressure in Veins less than that in arteries
– Thinner walls than arteries (tunica externa > tunica media, less
elastin)
– Larger lumen than arteries
– Contain valves (made of T. intima)
– Normal movement, Muscular contraction push blood through
• Venules- smallest veins
Cardiovascular Blood Flow
• Portal System: Special vascular circulation where
blood goes through 2 capillary beds before
returning to the heart to achieve 2nd function
– (eg) Hepatic Portal System: aids digestion by picking up
digestive nutrients from stomach + intestines and
delivers to liver for processing/storage
– Pick-up occurs at capillaries of stomach and intestine
– Via Hepatic Portal Vein goes to capillaries of liver
– Via Hepatic Vein blood goes back to heart
pg 338
Vascular Anastomoses
• Vessels unite and connect
• Arterial Anastomoses
– Communication between arteries
– Joints, Abdominal Organs, Brain, Heart
• Venous Anastomoses
– Communication between veins
– More common
– (eg) back of hand
pg 770
Fetal Circulation
• All major vessels in place by third month
• 2 main differences:
– 1. Fetus must supply blood to placenta
– 2. Lungs do not need much blood because
respiratory organ is the placenta
www.medical-illustrator.co.uk
1. Blood to Placenta
• Umbilical vessels
– Run in umbilical cord
– 2 umbilical arteries
• Carry blood (little oxygen and waste) to placenta
– 1 umbilical vein
• Returns this blood (with oxygen and nutrients) to fetus and to
portal vein (to liver)
pg 186
2. Bypassing the Lungs:
Foramen Ovale
www.nmtmedical.com/heartrepair.aspx?id=78
• Hole in the inter-atrial septum
• Allows blood to flow from RA to LA
• Bypasses the RV
– Would usually bring blood to lungs
• Becomes the fossa ovalis postnatally
2. Bypassing the Lungs:
Ductus Arteriosus
• Carries blood from pulmonary trunk to aortic arch
– Empties distal to coronary arteries
• This enables the heart and brain to receive the most highly
oxygenated blood
• Bypasses the lungs
• Becomes the ligamentum arteriosum postnatally
www.wellesley.edu/.../Courses/111/mammalian.html
First Breath!!
• Lungs inflate
– Ductus arteriosus constricts and closes
• Oxygenated blood begins pouring into LA for
first time
– Raises the pressure within the LA
– This pushes the 2 flaps of foramen ovale together
and closes it