The Heart and Circulation

1
The Heart and Circulation
Cardiovascular System Heart, Blood and
Vessels Lymphatic System Lymph nodes, Organs
and Vessels
2
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

3
Location of Heart in Chest

• 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 155
4
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 178
5
Pericardium
pg 178

• 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

6
External Features of Heart

• Interventricular sulcus
• Coronal/Coronary sulcus
• Auricles of atria
• Apex
• Base
• Coronary vessels
• Ligamentum Arteriosum

Pg 158
7
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 180
8
Layers of Heart

• Epicardium (most superficial)
• Visceral serosa
• Myocardium (middle layer)
• Cardiac muscle
• Contracts
• Endocardium (inner)
• Endothelium on CT
• Lines the heart
• Creates the valves

9
Fibrous Skeleton of Heart

• Insertion for cardiac muscle
• Anchors valve cusps
• Prevents valves from opening too much
• Block electrical impulses from atria to
  ventricles
• Contains AV node

Pg 170
10
Heart Chambers

• 2 receiving chambers
• Right atria
• Left atria
• 2 pumping chambers
• Right ventricle
• Left ventricle

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Right Heart Chambers Pulmonary Pump
pg 163, 165

• Right Atrium (forms most of base of heart)
• 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
• Pumps blood to lungs via Pulmonary Semilunar
  Valve in pulmonary trunk
• Trabeculae Carnae- muscle ridges along ventral
  surface
• Chordae Tendinae-fibrous cords running between AV
  valve cusps and papilary muscles
• Papillary Muscles (3)-cone-shaped muscles within
  ventricles to which chordae tendinae are anchored
• Moderator Band (septomarginal trabeucla)-muscular
  band connecting anterior papillary muscle to
  interventricular septum

12
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
• Pumps blood into aorta via Aortic Semilunar Valve
  to body
• Same structures as Rt Ventricle Trabeculae
  carnae, Papillary muscles (2), Chordae tendinae
• No Moderator band

13
Heart Valves Lub-Dub

• Tricuspid Valve Right AV valve
• 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 165
14
Semilunar Valves (the dub)

• 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 theyre pushed down (valve closed)

pg 165
15
Flow of Blood

• O2-poor blood (SI 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

16
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

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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

18
Blood Flow to Supply the Heart Muscle

• Heart wall too thick for diffusion of nutrients
• Rt and Lft Coronary Arteries
• 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 171
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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

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Anatomy of Arteries and Veins

• Tunica externa
• Outermost layer
• CT w/elastin and collagen
• Protects, Strengthens, Anchors
• Tunica media
• Middle layer
• Circular Smooth Muscle
• Collagen Elastic Fibers
• Vaso-constriction/dilation
• Tunica intima
• Innermost layer
• Endothelium
• Minimize friction
• Lumen

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Vessels of Cardiovascular SystemArteries

• Carry blood AWAY from heart
• Systemic Circuit carry O2 blood
• Pulmonary Circuit carry de-O2 blood
• Walls thicker than Veins
• Tunica media gt Tunica externa
• 3 Types
• Conducting (elastic)
• large, elastin, high pressure
• Distributing (muscular)
• medium size, to organs
• Arterioles
• smallest

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Capillaries

• Smallest BV
• Usually 1 RBC thick
• 1 layer endothelial cell thick surrounded by
  basal lamina
• 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

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Vessels of Cardiovascular SystemVeins

• 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 gt
  tunica media, less elastin)
• Larger lumen than arteries
• Contain valves (made of T. intima)
• Normal movement, Muscular contraction push blood
  through
• Venules- smallest veins

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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

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Vascular Anastomoses

• Vessels unite and connect
• Arteriole Anastomoses
• Communication between arteries
• Joints, Abdominal Organs, Brain, Heart
• Venous Anastomoses
• Communication between veins
• More common
• (eg) back of hand
• Vaso Vasorum
• Tiny arteries, veins, capillaries in tunica
  externa of vessels to nourish them (outer half)

pg 726
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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

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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)
• Ductus venosus
• Shunt that puts blood to hepatic veins, IVC, and
  RA from placenta
• Too much blood for liver to handle
• Results in highly O2 blood going to heart

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2. Bypassing the LungsForamen Ovale

• Becomes Fossa Ovalis
• Hole in the inter-atrial septum
• Allows blood to flow from RA to LA
• Bypasses the RV
• Would usually bring blood to lungs

pg 163
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2. Bypassing the Lungs Ductus Arteriosus

• Becomes Ligamentum arteriosum
• 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

pg 186
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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