Lecture 17: Circulatory System Heart

Question 1

Circulatory System

Answer 1

Distributes oxygen and nutrients to body, and picks up waste materials to be eliminated by respiratory and urinary system
Includes heart and blood vessels

Question 2

Mediastinum borders

Answer 2

Anterior border: sternum, costal cartilage
Lateral border: lungs
Posterior border: thoracic vertebrae
Superior border: manubrium of of sternum, ribs 1, T1
Inferior border: diaphragm
Contains heart, large vessels, esophagus, trachea, thoracic aorta

Question 3

Parts of the mediastinum

Answer 3

Transverse plane through sternal angle at TIV, and TV divide it to superior and inferior mediastinum
Inferior mediastinum divided into 3 regions: anterior (in front of heart, between sternum and pericardium), middle (heart, surrounding membranes, pericardium), posterior (behind heart, between pericardium and vertebrae of TV-TXII)

Question 4

Superior mediastinum

Answer 4

Contains:
Arch of aorta and branches (brachiocephlic artery, L common carotid artery, L subclavian artery)
R/L brachiocephalic veins, inferior part of superior vena cava, end of azygus vein
R/L phrenic and vagus nerve
Trachea, esophagus, thymus gland, thoracic duct

Question 5

Anterior mediastinum

Answer 5

Contains:
thymus gland
Over age 25 - becomes loose connective tissue and fat

Question 6

Middle mediastinum

Answer 6

Contains: 
Heart and pericardium
Ascending aorta, pulmonary trunk, pulmonary veins
R/L phrenic nerves
Main bronchi

Question 7

Posterior mediastinum

Answer 7

Contains:
Descending aorta, azygus, hemiazygus veins
R/L vagus nerve
Sympathetic chains and splachnic nerve
Thoracic duct and esophagus

Question 8

Heart

Answer 8

Muscular pump in middle mediastinum (size of fist)
Superior and inferior collects venous/deoxygenated blood to body and sends it to R atrium -> R ventricle -> lungs (pulmonary circulation)
L atrium receives oxygenated blood from lungs via pulmonary vein -> L ventricle -> body (systemic circulation)

Question 9

Surface anatomy of heart

Answer 9

Upper L corner: L 2nd intercostal space, 1 inch away from midline
Upper R corner: R 3rd costal cartilage, 1 inch away from midline
Lower R corner: R 6th costal cartilage, 1 inch away from midline
Lower L corner: L 5th intercostal space, 3-4 inches away from midline

Question 10

Heart sulci

Answer 10

Coronary sulcus
Anterior interventricular sulci
Posterior interventricular sulci

Question 11

Coronary sulcus / Atrial-ventricular sulcus

Answer 11

Encircles heart
Separates atria and ventricles
Contains coronary artery

Question 12

Interventricular sulci

Answer 12

2 of them

Separates ventricles on anterior and inferior surface

Question 13

Heart surfaces

Answer 13

Anterior/sternocostal surface
Inferior/diaphragmatic surface
Left pulmonary surface
Right pulmonary surface

Question 14

Anterior / Sternocostal surface

Answer 14

In touch with sternum and 2-6 costal cartilages

Consists of R ventricle, R atrium, L ventricle

Question 15

Inferior / diaphragmatic surface

Answer 15

Leans on diaphragm
Consists of L ventricle and R ventricle
Has posterior interventricular sulcus
Contains superior and inferior vena cava, pulmonary veins (2 per side)

Question 16

L/R pulmonary surface

Answer 16

L - related to L lung, has L ventricle and L atrium

R - related to R lung, has R atrium

Question 17

Base of heart

Answer 17

Faces posteriorly

Formed by L atrium and R atrium

Question 18

Apex of heart

Answer 18

L ventricle
Directed anteriorly, inferiorly, to the L
Sits in 5th intercostal space on L, 3 inches away from sternum

Question 19

Heart borders

Answer 19

Superior border - R/L atria and auricles
R border - R atrium
L border - L ventricle and L auricle
Inferior border - R ventricle and L ventricle (separates anterior and inferior surface)

Question 20

R atrium

Answer 20

Get venous blood from superior vena cava, inferior vena cava, and coronary sinus
Pectinate muscles lines anterior part and extends to R auricle
Fossa ovalis
R atrioventricular/tricuspid valve - guards R atrioventricular opening that connects to R ventricle

Question 21

Fossa ovalis

Answer 21

In interatrial septum
Remnant of embryonic foramen ovalis that used to connect R/L atrium
In embryonic stage, blood was oxygenated in R atrium by placenta, and the moment the baby cries, the connection is cut (due to pressure change)

Question 22

R ventricle

Answer 22

Walls are thicker than R atrium
Trabeculae carneae (muscle fibers)
Papillary muscles (3)
Pulmonary artery from superior part
Pulmonary/semilunar valve that prevents blood flowing back
Interventricular septum (separates L/R ventricle)

Question 23

Papillary muscles

Answer 23

Group of trabeculae carneae

Finger like projections from walls of ventricles that insert into tricuspid/bicuspid valve via chorda tendinae

Question 24

L atrium

Answer 24

Receives oxygenated blood from R/L pulmonary veins
Pectinate muscles in L auricle
L atrioventricular/bicuspid/mitral valve guards L atrioventricular opening connecting to L ventricle

Question 25

L ventricle

Answer 25

``` Thickest walls Trabeculae carneae Papillary muscles (2) Aorta from superior part Aorta/semilunar valve that prevents blood flowing back ```

Question 26

Pericardial sac

Answer 26

Surrounds the heart | Composed of fibrous pericardium (outer) and serous pericardium (inner)

Question 27

Fibrous pericardium

Answer 27

Dense connective tissue Attaches to central tendon of diaphragm inferiorly, and great vessels of heart superiorly Mechanically protects the heart

Question 28

Serous pericardium

Answer 28

2 layers to secrete serous fluid Parietal layer lines inner fibrous pericardium Visceral layer (epicardium) attaches to heart

Question 29

Pericardial cavity

Answer 29

Space between parietal and visceral layers of serous pericardium Filled with serous fluid Lubricates heart to facilitate movement

Question 30

Conducting system of heart

Answer 30

Sinuatrial (SA) node Atrioventricular (AV) node Atrioventricular bundle (bundle of his) Electrical impulses from modified myocardial cells start at SA node, propagates and contracts atrial walls before AV node. Impulse passes ventricular walls via bundle of His and Purkinje fibers to ventricular contraction via myocytes. Will give rise to a heart rate at a lower rate

Question 31

Sinuatrial node

Answer 31

Heart pacemaker | R atrial wall close to superior vena cava opening

Question 32

Atrioventricular node

Answer 32

R side of interatrial septum close to opening of coronary sinus

Question 33

Atioventricular bundle

Answer 33

Starts at AV node -> interventricular septum -> L/R branches -> Purkinje fibers -> R/L ventricular walls

Question 34

ANS and heart rate

Answer 34

Preganglionic sympathetic fibers from T1-T5 lateral horn to paravertebral sympathetic ganglion to cardiac plexus under aortic arch; increases heart rate Preganglionic parasympathetic fibers from vagus nerve in medulla to cardiac plexus; decreases heart rate

Question 35

Visceral afferent of cardiac plexus

Answer 35

Fibers with parasympathetic system (vagus nerve) - detect change in blood pressure/chemical content, and cardiac reflex Fibers with sympathetic system return to upper 4-5 thoracic segments and conduct pain sensation from heart

Question 36

R coronary artery

Answer 36

From R ascending aorta to R coronary sulcus Supplies R atrium and R ventricle R marginal artery (when passing R side) Terminal branch, posterior interventricular artery, runs in posterior interventricular sulcus and supplies to posterior aspect of ventricles

Question 37

L coronary artery

Answer 37

From L ascending aorta Branches to anterior interventricular artery and circumflex artery Anterior interventricular artery (left anterior descending artery) runs in anterior interventricular sulcus and supplies to anterior aspect of ventricles Circumflex artery follows coronary sulcus to L side supplying to L atrium and L ventricle

Question 38

Venous Drainage of heart

Answer 38

3 major veins Great cardiac vein (anterior interventricular sulcus) Middle cardiac vein (posterior interventricular sulcus) Small cardiac vein (R coronary sulcus; follows R marginal artery) All drain into coronary sinus in coronary sulcus on inferior surface, which drains into R atrium