Chapter 18, The Heart

1
Chapter 18, The Heart

• Class demonstrations

2
Two main functions

• Pulmonary circulation
• Superior inferior vena cava
• R atrium
• R ventricle
• Pulmonary arteries
• Lungs oxygenation
• Pulmonary veins
• Return to heart

18.1
3
Two main functions

• Systemic circulation
• L atrium
• L ventricle
• Aorta
• Arteries
• Capillaries
• Tissues
• Veins
• Vena cava

18.1
4
Location of heart

• Thorax
• Posterior to sternum costal cartilages
• Mediastinum (between lungs)
• Superior to diaphragm
• Anterior to vertebrae and large vessels

18.2abc
5
Location of heart

• Apex of heart
• Left side
• Between ribs 5-6
• Below nipple
• Base of heart
• Posterior surface

5
6
18.2a
6
Pericardium
18.2c

• 3 layered sac
• Fibrous pericardium
• Protective layer
• Attached to great vessels (aorta, pulmonary
  artery veins)
• Attached to diaphragm
• Anchors heart in place

18.3
7
Pericardium

• Serous pericardium
• Parietal layer
• Visceral layer
• Pericardial cavity
• Serous fluid
• Permits movement

18.3
8
Heart wall layers
18.3

• Epicardium
• Visceral layer of serous pericardium
• Myocardium
• Cardiac muscle fibers
• Arranged in bundles
• Squeezes blood out of heart
• Endocardium
• Continuous with endothelium

18.4
9
Heart chambers

• R-L atria
• R-L ventricles
• Interatrial septum
• Interventricular septum

18.5be
10
External landmarks

• Coronary sulcus
• Anterior interventricular sulcus
• Posterior interventricular sulcus

18.5bd
11
R Atrium

• External landmarks
• R auricle (not labeled)

18.5ad
12
R atrium
not in text

• Internal landmarks
• Superior inferior vena cava
• Coronary sinus
• Fossa ovalis
• Former foramen ovale

18.5e
13
Foramen ovale

• In fetus
• Shunts 1/2 blood from R to L
• Closes at birth (fossa ovale)

19.26a
14
Prenatal Heart Animation

• http//www.heartcenteronline.com/myheartdr/home/sh
  ow_animations.cfm?cmbtopics174
• this is slow sometimes

15
R atrium

• Tricuspid valve
• R atrioventricular valve

18.5e
16
R ventricle

• External landmarks
• Coronary sulcus
• Anterior interventricular sulcus
• Posterior interventricular sulcus

18.5b
17
R ventricle

• Internal landmarks
• Trabeculae carnae
• Tricuspid valve
• Valve flaps
• Chordae tendineae
• Papillary muscles
• Pulmonary trunk
• Pulmonary semilunar valve

18.5e
18
L atrium

• External landmarks
• 2R 2L pulmonary veins
• L auricle

18.5bd
19
L atrium

• Internal landmarks
• 4 pulmonary veins
• Mitral valve
• L atrioventricular valve
• Bicuspid valve

18.5e
Episcopal Bishop Persell of Chicago wearing a
miter.
20
L ventricle

• External landmarks
• Coronary sulcus
• Anterior-posterior interventricular sulci
• Apex

18.5bd
21
L ventricle
18.5e

• Internal landmarks
• Mitral valve
• Chordae tendineae
• Papillary muscles
• Trabeculae carnae
• Ascending aorta
• Aortic semilunar valve
• Thicker myocardium

18.7
22
Path of blood through the heart

• Superior inferior vena cava and coronary sinus
• R atrium
• Tricuspid valve
• R ventricle
• Pulmonary semilunar valve
• Pulmonary trunk
• (lungs)

18.17a
23
Path of blood through the heart

• 4 pulmonary veins
• L atrium
• Mitral valve
• L ventricle
• Aortic semilunar valve
• Ascending aorta

18.17a
24
Heartbeat

• Two atria contract
• Two ventricles contract
• 70-80 heartbeats / min, average
• Systole contraction
• Diastole relaxation

25
AV valves

• Prevent backflow from ventricles to atria
• Diastole of ventricles, systole of atria
• Valve open
• Systole of ventricles, diastole of atria
• ? BP in ventricles
• AV valves close
• Papillary muscles contract
• ? tension on chordae tendineae

18.9ab
26
Semilunar valves

• Three cusps
• Prevent backflow from aorta pulmonary trunk
  into ventricles
• Passive action
• Systole of ventricles opens valves
• Diastole of ventricles
• ? BP
• Backflow fills cusps and closes valve

18.10ab
27
Heart sounds

• lub dub
• lub closing of AV valves
• dub closing of semilunar valves

(Synapse Publishing,Inc.)
http//www.medlib.com/spi/coolstuff2.htm
28
Heart conducting system

• Cardiac muscle fibers form 2 networks via gap
  junctions at intercalated discs
• Atrial network
• Ventricular network

4.14b
18.4
29
Heart conducting system

• Sinoatrial node
• Internodal fibers
• Atrioventricular node
• Atrioventricular bundle
• Bundle branches
• Purkinje fibers

18.12
30
Heart conducting system

• Sinoatrial (SA) node
• In R atrial wall
• Pacemaker
• Generates AP
• Triggers contraction of atria
• Sends AP along internodal path

18.12
31
Heart conducting system

• Atrioventricular (AV) node
• Triggers ventricular contraction
• Relays AP to AV bundle
• RL bundle branches
• Interventricular septum
• Purkinje fibers
• Near apex
• Turn superiorly

18.12
32
Parasympathetic innervation

• Slows heart rate
• Pathway
• Reticular formation in medulla
• Cardioinhibitory center
• Vagus nerve (CN X)
• To SA AV nodes
• ACh

18.13
33
Sympathetic innervation

• ? heart rate
• ? force of contraction
• Cardioacceleratory center
• Medullary reticular formation
• Preganglionic sympathetic neurons in thoracic
  spinal cord
• Postganglionic sympathetic neurons to SA AV
  nodes
• NE, NE ? ? R

18.13
34
Coronary circulation

• L coronary artery
• From ascending aorta
• Two branches
• Anterior interventricular artery (LAD)
• Branches to RL ventricles, interventricular
  septum
• Circumflex artery
• Supplies L atrium
• Coronary sulcus

18.14a
35
Coronary circulation

• R coronary artery
• From ascending aorta
• In coronary sulcus
• Two branches
• Marginal artery
• Posterior interventricular artery
• Supplies R atrium and ventricle

18.14
36
Coronary Art. Bypass Surgery

• http//www.heartcenteronline.com/myheartdr/home/sh
  ow_animations.cfm?cmbtopics183