Cardiovascular system

Larry M. Frolich, Ph.D.,Human Anatomy

CARDIO-VASCULAR SYSTEM

• Principles• Structures• Two circuits

– Pulmonary– Systemic

• Fetal Circulation• Heart Details• Other details


What Does C-V System do?

• Circulate blood throughout entire body for– Transport of oxygen to cells– Transport of CO2 away from cells– Transport of nutrients (glucose) to cells– Movement of immune system components

(cells, antibodies)– Transport of endocrine gland secretions


How does it do it?

• Heart is pump• Arteries and veins are main tubes (plumbing)

– Arteries Away from Heart– Veins to Heart

• Diffusion happens in capillaries (oxygen, CO2, glucose diffuse in or out of blood)


• Heart/Great Vessels--1 Route

• Smaller aa. vv.--many routes (collateral circulation)

• Capillaries—network where diffusion occurs

Overall Organization of System


Collateral Circulation


Walls of Arteries and Veins

• Tunica externa– Outermost layer– CT w/elastin and collagen– Strengthens, Anchors

• Tunica media– Middle layer– Circular Smooth Muscle– Vaso-constriction/dilation

• Tunica intima– Innermost layer– Endothelium– Minimize friction

• Lumen pg 546


Artery/Vein differencesArteries (aa.) Veins (vv.)

Direction of flow

Blood Away from Heart

Blood to Heart

Pressure Higher Lower

Walls THICKER: Tunica media thicker than tunica externa

THINNER: Tunica externa thicker than tunica media

Lumen Smaller Larger

Valves No valves Valves (see next)


Capillaries• Microscopic--one

cell layer thick• Network • Bathed in

extracellular matrix of areolar tissue

• Entire goal of C-V system is to get blood into capillaries where diffusion takes place


Two circulatory paths

Pulmonary

Systemic


GREAT VESSELS•Aorta•IVC, SVC•Pulmonary Trunk•Pulmonary Veins


Heart Chambers and Valves


Right Heart Chambers: Pulmonary Circuit

• Right Atrium (forms most of posterior of heart)– Receives O2-poor blood from body via IVC, SVC, Coronary sinus

– Ventral wall = rough Pectinate muscle– 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 along ventral surface

– Papillary Muscle-cone-shaped muscle to which chordae tendinae are anchored

– Moderator Band-muscular band connecting anterior papillary muscle to interventricular septum


Left Heart Chambers: Systemic Circuit

• 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, Chordae tendinae

– No Moderator Band


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 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 Lft. Ventricle by chordae tendinae– Functions same as Rt. AV valve

• **Semilunar valves: prevents backflow in large arteries– Pulmonary Semilunar Valve: Rt Ventricle and Pulmonary Trunk– Aortic Semilunar Valve: Left Ventricle and Aorta– 3 cusps: blood rushes past they’re flattened, as it settles they’re pushed

down (valve closed)


Another View


Location of Heart in Thorax

pg 523


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


Heart Wall

• Epicardium (most superficial)– Visceral pleura

• Myocardium (middle layer)– Cardiac muscle– Contracts

• Endocardium (inner)– Endothelium on CT– Lines the heart – Creates the valves

pg 524

How does heart muscle get blood supply?


Blood supply to heart wall

• 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– Sit in Coronary Sulcus


Heart Innervation• Heart receives visceral

motor innervation– Sympathetic (speeds up)– Parasympathetic (slows

down) p. 534


Fetal Circulation•No circulation to lungs

•Foramen ovale•Ductus arteriosum

•Circulation must go to placenta•Umbilical aa., vv.


Adult remnants of fetal circulation

Adult Fetus

Fossa ovale Foramen ovale

Ligamentum arteriosum Ductus arteriosus

Medial umbilical ligaments Umbilical aa.(within fetus)

Round ligament (ligamentum teres) of liver

Umbilical v.(within fetus)

Ligamentum venosum Ductus venosus

Medial umbilical ligament Umbilical cord (leaving fetus)


Hepatic Portal System


Lymphatic System…The Players:

• Lymph- clear fluid from loose areolar CT around capillaries

• 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)– Lumbar, intestinal, bronchomediastinal, subclavian, jugular

• Lymphatic ducts empty into veins of neck


Lymphatic System--Function

• Function: to collect excess tissue fluid collecting at arteriole end and return leaked blood proteins to blood (maintain osmotic pressure needed to take up water into bloodstream)

• Lymph moved through vessels– Pulse of nearby arteries– Contraction of surrounding skeletal muscle– Regular movement of body (wiggling legs)– Muscle in Tunica Media

• Lacteals-lymphatic capillaries w/unique function– In mucosa of small intestine, receive digested fat from

intestine– Fatty lymph becomes milky = Chyle– Chyle goes to bloodstream

Cardiovascular system

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