Cardiovascular system

2. FUNCTIONS OF THE HEART
1.Generating blood pressure
2.Routing blood
3.Ensuring one-way blood flow
4.Regulating blood supply

4. -The right side of the heart pumps blood to the lungs and back to
the left side of the heart through vessels of pulmonary
circulation.
-The left side of the heart pumps blood to all other tissues of the
body and back to the right side of the heart through vessels of
the systemic circulation.

5. SIZE, FORM, LOCATION OF THE HEART
 Shaped like a blunt cone and is approximately the size of the closed fist.
 Apex- blunt, rounded point of the heart
 Base- larger, flat part at the opposite end of the heart
 Location-thoracic cavity between the two pleural cavities that surround the lungs.
 Surrounded by the pericardial cavity.
 The heart lies obliquely in the mediastinum, with its base directed posteriorly and
slightly superiorly and its apex directed anteriorly and slightly inferiorly.

6. Pericardium

7. Two layers:
fibrous pericardium
-outer layer (tough connective tissue)
serous pericardium
-inner layer (flat epithelial cells with a thin layer
of connective tissue.
Two parts:
parietal pericardium- lining the fibrous
pericardium
visceral pericardium- covers the heart
surface

8. EXTERNAL ANATOMY

10. Six large veins carry blood to the atria of the heart:
Superior vena cava & inferior vena cava
-carry blood from the body to the right atrium.
Pulmonary veins (4)
-carry blood from the lungs to the left atrium
Arteries (2) (great vessels/great arteries)
-carry blood away from the ventricles of the heart
Pulmonary trunk ( splits into R & L pulmonary
arteries)
- Carry blood to the lungs
Aorta
-carries blood to the rest of the body

11. HEART CHAMBERS & INTERNAL
ANATOMY
4 CHAMBERS: RIGHT & LEFT ATRIA; RIGHT & LEFT VENTRICLES
RIGHT AND LEFT ATRIA
Right atrium receives blood from 3 major openings:
1. Superior vena cava
2. Inferior vena cava drain blood from most of the body
3. Coronary sinus – drains blood from most of the heart muscle
LEFT ATRIUM
-receives blood through the 4 pulmonary veins, which drain blood from the lungs.
Interatrial septum- separates 2 atria from each other

12. Right & Left Ventricles
-major pumping chambers
-eject blood into the arteries and force it to flow
through the circulatory system.
Right ventricle pumps blood into the pulmonary
trunk
Left ventricle pumps blood into the aorta.
Interventricular septum
-separates the 2 ventricles from each other

14. Heart valves
2 types:
Atrioventricular (AV) valves-located in between each atrium and ventricle
Semilunar valves-located between each ventricle and its associated great artery
Tricuspid valve – AV valve between right atrium and right ventricle
Bicuspid valve - AV valve between left atrium and left ventricle
Papillary muscles-cone-shaped, muscular pillars of each ventricle.
Chordae tendineae (heart strings)-thin, strong, connective tissue strings that attach the
papillary muscles to the AV valve cusps.
Pulmonary semilunar valve- between the right ventricle and pulmonary trunk
Aortic semilunar valve- located between the left ventricle and aorta

17. ROUTE OF BLOOD FLOW THROUGH
THE HEART

18. BLOOD SUPPLY TO THE HEART
CORONARY ARTERIES
-supply blood to the wall of the heart
CARDIAC VEINS
-drain blood from the cardiac muscle
LEFT CORONARY ARTERY
3 MAJOR BRANCHES:
1. Anterior interventricular artery
2. Circumflex artery
3. Left marginal artery

20. HISTOLOGY OF THE HEART
HEART WALL
-Composed of 3 layers of tissue:
1. Epicardium
2. Myocardium
3. Endocardium
Epicardium/visceral pericardium
-thin, serous membrane forming the smooth outer surface of the heart.
-simple squamous epithelium overlying a layer of connective tissue and adipose tissue.
Myocardium
-thick, middle layer of the heart
-composed of cardiac muscle cells
-responsible for contraction of the heart chambers
Endocardium
-smooth, inner surface of the heart
-simple squamous epithelium over a layer of connective tissue
-allows blood to move easily through the heart

22. CARDIAC MUSCLE

23. -elongated, branching cells that contain one, or occasionally
two, centrally located nuclei.
-contain actin and myosin myofilaments organized to form
sarcomeres, which are joined end-to-end to form myofibrils.
-cardiac muscle cells are bound end-to-end and laterally to
adjacent cells by specialized cell-to-cell contacts called
intercalated disks.
Gap junctions
-specialized cell membrane structures in the intercalated disks
-allow cytoplasm to flow freely between cells which enables
action potentials to pass quickly and easily from one cell to the
next.

24. ELECTRICAL ACTIVITY OF THE HEART
-action potentials in the cardiac muscle take approximately 200 to 500
milliseconds to complete.

26. CONDUCTION SYSTEM OF THE HEART
Contraction of the atria and ventricles is coordinated by specialized cardiac muscle cells in the heart
wall that form the conduction system of the heart.
 Includes SINOATRIAL (SA) NODE, ATRIOVENTRICULAR NODE (AV) NODE, ATRIOVENTRICULAR
BUNDLE, RIGHT AND LEFT BUNDLE BRANCHES, PURKINJE FIBERS.
SINOATRIAL (SA) NODE
-located in the superior wall of the right atrium and initiates the contraction of the heart.
-action potentials originate in the SA node
ATRIOVENTRICULAR (AV) NODE
-located in the lower portion of the right atrium
-when action potentials reach the AV node, they spread slowly through it and then into the
bundle of specialized cardiac muscle called AV bundle.
AV BUNDLE
-separates the atria from the ventricles.
-divides into 2 branches of conducting tissue: left and right bundle branches.
PURKINJE FIBERS
-pass to the apex of the heart and then extend to the cardiac muscle of the ventricle walls.

27. CONDUCTION SYSTEM OF THE HEART

28. ELECTROCARDIOGRAM
Electrodes placed on the body surface and attached to a recording device can detect the
small electrical changes resulting from the action potentials in all of the cardiac muscle
cells.
-normal ECG consists of a P wave, a QRS complex, T
wave.
P wave
-results from depolarization of the atrial
myocardium, and the beginning precedes the onset
of atrial contraction.
QRS complex
-results from depolarization of the ventricles, and
the beginning precedes ventricular contraction.
T wave
-represents repolarization of the ventricles
-beginning of the T wave precedes ventricular
relaxation.

30. Cardiac cycle
-refers to the repetitive pumping process that begins with the onset of cardiac muscle
contraction and ends with the beginning of the next contraction.
-at the beginning of the cardiac cycle, the atria and ventricles are relaxed, the AV valves
open, blood flows into the ventricles, filling them to approximately 70% of their volume.
(step 1)
ATRIAL SYSTOLE-the atria contract, forcing additional blood to flow into the ventricles to
complete their filling. Semilunar valves remain closed. (step 2)
VENTRICULAR SYSTOLE-at the beginning of ventricular systole, contraction of the
ventricles pushes blood toward the atria, causing the AV valves to close as the pressure
begins to increase. (step 3)
As ventricular systole continues, the increasing pressure in the ventricles exceeds the
pressure exceeds the pressure in the pulmonary trunk and aorta, the semilunar valves
are forced open, and blood is ejected into the pulmonary trunk and aorta (step 4)
VENTRICULAR DIASTOLE-at thee beginning of ventricular diastole, the pressure in the
ventricles decreases below the pressure in the aorta and pulmonary trunk. The semilunar
valves close and prevent blood from flowing back into the ventricles. (step 5)

32. HEART SOUNDS
STETHOSCOPE
-originally developed to listen to the sound of the
lungs and heart and is now used to listen to other
sounds of the body as well.
Two main heart sounds:
First sound: lubb
2nd sound: dupp
First sound occurs at the beginning of ventricular
systole and results from closure of the AV valves
Second sound occurs at the beginning of ventricular
diastole and results from closure of the semilunar
valves.

34. REGULATION OF HEART FUNCTION
Cardiac Output (CO)
-volume of blood pumped by either ventricle of the heart each minute.
Stroke Volume (SV)
-volume of blood pumped per ventricle each time the heart contracts
Heart Rate (HR)
-number of times the heart contracts each minute.
Formula:
CO = SV X HR
(ml/min) (ml/beat) (beats/min)
Example: In resting condition, the heart rate is approximately 72 beats/min, and stroke
volume is approximately 70mL/beat.
CO=70 mL/beat x 72 bpm
= 5040 mL/min (approx. 5 L/min)

35. INTRINSIC REGULATION
-Refers to mechanisms contained within the heart itself
Preload-degree to which the ventricular walls are stretched at the end
of the diastole.
Venous return-the amount of blood that returns to the heart.
Afterload- pressure against which the ventricles must pump blood.
EXTRINSIC REGULATION
-refers to mechanism external to the heart, such as venous or chemical
regulation.
nervous regulation: BARORECEPTOR REFLEX
-Mechanism of nervous system that plays an important role in
regulating heart function.

37. Chemoreceptor reflex
-maintains homeostasis in response to changes in blood conc. Of CO2 and H+ (pH)

38. EFFECTS OF AGING ON THE HEART
By age 70, cardiac output decreases to approx.
one-third.
Hypertrophy
By age 85, Cardiac output decreases 30-60%
Connective tissue becomes less flexible,
calcium deposits develop in the valves.
Increase in cardiac arrhytmias
Coronary artery disease and heart failure