Anatomy & Physiology
The Cardiovascular System
1. Location and Size
· Located enclosed within the medial cavity of the thorax (space between the lungs). This area is called the _mediastinum____
· The heart is cone shaped.
-inferior to the apex is the _diaphragm______
-lateral to the heart are the _lungs______
-anterior to the heart is the _sternum & ribs______
-posterior to the heart is the _esophagus & vertebrae__
· The majority of the hearts mass (2/3) lies towards the left of the midline of the body
· The axis of the heart lies in an oblique line
atria toward right shoulder, ventricles toward left hip
· Starts at the level of the 5th rib and extends 5cm to approx. the 5th intercostals space
Draw a basic picture of the upper body and place heart in the correct orientation drawing in the:
-right atrium, right ventricle, left atrium, and left ventricle
2. Layers of the Heart Wall
· There are 3 layers of the heart wall
a) _epicardium______
- = visceral pericardium
-outermost layer of the heart
-often infiltrated with fatty deposits in older people
b)_myocardium______
-“muscle heart”
-composed mainly of cardiac muscle
-area that actually contracts
-middle layer that forms the bulk of the heart
c)_endocardium______
-innermost layer- lines the inside of the heart and covers the valves
-consists of epithelium (squamous) and connective tissue (lots of collagen & elastin)
-continuous with the great vessels associated with the heart (aorta, pulmonary vessels and vena cava)
3. Chambers of the Heart
· The interior of the heart consists of four chambers
-2 superior chambers called _atria______
-2 inferior chambers called __ventricles______
The Atria
a) the right atrium receives blood from the _systemic circulation_____(body) from what 3 sources:
· _superior vena cava_____
· _inferior vena cava______
· _coronary sinus______
b) the left atrium receives blood from the _pulmonary system (lungs)______from what 4 sources:
· _4 pulmonary_veins______
· there is a septum dividing the atria called the _interarterial septum___
The Ventricles
· more massive chambers, thick myocardium
· function to pump (discharge) blood into the system
i. the right ventricle pumps _deoxygenated______(low O2) blood from the right atria to the lungs (pulmonary system) via the pulmonary trunk
ii. the left ventricle pumps _oxygenated______(high O2) blood from the heart into the aorta and systemic arteries to be distributed to the tissues of the body (systemic system).
iii. There is a septum dividing the ventricles called the _interventricular septum_____
iv. The myocardium of the left ventricle is much thicker than the right ventricle and pumps at a much higher pressure. WHY?
-because it has to pump to the whole body (systemic circulation) and not just the pulmonary system
v. What is the fibrous skeleton of the heart?(where located)
-dense connective tissue rings surround heart valves, fuse and merge with interventricular septum
a) What are the 3 main functions?
· _support______-structure for heart valves
· _insertion______-point for cardiac muscle bundles
· _electrical insulator___-between atria and ventricles – prevents direct propagation of action potentials to ventricles
4. Valves of the Heart
· Blood only flows in one direction
Ø from the atria to the ventricles
Ø This unidirectional flow is controlled by 4 heart valves:
a) 2 _atrioventricular_____ valves
b) 2 _semilunar______valves
· Whether the valves are opened or closed depends on the _pressure______difference on either side of the valve.
a) Atrioventricular (AV) Valves
· One located between each of the atrial-ventriclular junction
· Prevent _backflow______of blood from the ventricles into the atria during a contraction
· Blood filling the ventricles closes the valves
· _Chordae tendinae____ attach the flaps to intraventricular muscles called_papillary muscle____.
· During the contraction of the ventricles these muscles contract and anchor the valves in a closed position. (prevent backflow into the atria)
There are two:
i) The right AV valve= the _tricuspid______
- located between the right atrium and right ventricle
- has 3 flexible flaps of endocardium
ii)The left AV valve= the _bicuspid______or the _mitral______
- located between the left atrium and the left ventricle
- has 2 flexible flaps of endocardium
b) Semilunar (SL) Valves
· Prevent _backflow______of blood from the large arteries exiting the heart back into the ventricles
· Each is made of 3 half moon shaped cusps.
· Contraction of the heart (increases or decreases) the pressure within the ventricle which forces the valve open allowing blood to leave the heart
· When the ventricle relaxes, pocket like flaps on the valve fill with back flowing blood and _close_____the valve* prevents blood from re-entering the ventricle
· There are no chordae tendoneae or papillary muscles to keep the valves closed
NOTE: First heart sound is the closure of the AV valves (“LUB” or “DUB”)
Second heart sound is the closure of the SL valves (“LUB” or “DUB”)
(circle correct answer)
5. Blood Vessels that Enter & Leave the Heart
· The blood vessels form a closed system
Ø _arteries______carry blood away from the heart
Ø _veins______carry blood toward the heart
Note: it is (not true or true) to say that arteries always carry oxygenated blood and veins always carry deoxygenated blood. Think of the pulmonary system!
Major Veins Entering the Heart
1. __SVC______returns blood from the body regions above the diaphragm
2 .__IVC______returns blood from the body regions below the diaphragm
3. __coronary sinus______returns blood to the heart from the myocardium itself
4. __pulmonary vein______returns blood from the lungs back to the heart
Major Arteries Leaving the Heart
1._pulmonary artery______transport blood away from the heart to the lungs
2. _aorta______transports blood away from the heart to the body tissues
6. The Pathway of Blood Through the Heart & Pulmonary System
1. Describe the pathway for pulmonary circulation starting at the right atrium.
See text !
2. Describe the systemic circulation starting at the left ventricle.
See text
3. Describe blood circulation involving both pulmonary and systemic circulation.
See text!
7. The Cardiac Cycle – Refer to Lecture notes for in depth explanation
· The cardiac cycle represents the events of one heartbeat
a) _systolic______refers to the contraction phase
b) _diastolic______refers to the relaxation phase
** Note that the flow of blood through the heart is entirely due to pressure changes and blood flow along a pressure gradient from high pressure to low pressure**
c) The left side of the heart exhibits high pressure (120/80) compared to the right side of the heart. WHY?
-pumping to larger area than lungs
Coronary Circulation
b) the blood passing through the chambers of the heart doesn’t nourish the heart muscle
c) the heart itself receives it’s blood supply from _coronary arteries______
d) the right and left coronary arteries are the _first (main)____ branches off the aorta
e) these arteries branch of the aorta at the level of the _semilunar_____valves
f) the heart only receives it’s blood supply when the heart is _relax______- diastole
Ø during systole, the open semilunar valves block the openings to the coronary arteries
· cardiac veins drain blood from the heart and empty it into an area called the _coronary sinus______located on the posterior surface of the heart
· this sinus then empties into the right atrium
8. Heart Disease
a) What are some causes of congested heart failure
-coronary artery disease, hypertension, MI, valve disorders, congenital defects
b) Fill in the appropriate statements with the answer left or right side failure of the heart.
· _Left______-suffocation & lack of oxygen t the tissues
· _Left______-heart is overstretched & even more blood remains
· _Right______-fluid builds up in tissues as peripheral edema
· _Left______-less effective pump so more blood remains in ventricle
· _Left______-blood backs up into lungs as pulmonary edema
c) Name 5 risk factors in heart disease (if you can come up with more that would be great!)
· _high blood cholesterol level__
· _high blood pressure______
· _cigarette smoking______
· _obesity______
· _lack of exercise__________
-others diabetes mellitus, genetic predisposition, male gender, high blood levels of fibrinogen, left ventricular hypertrophy
d) Why is high blood cholesterol a risk factor for developing heart disease?
-promotes growth of fatty plaques
e) What do these symbols stand for and briefly how are they involved with cholesterol?
HDL-high density lipoproteins
-remove excess cholesterol from circulation
LDL-low density lipoproteins
-associated with formation of fatty plaques
VLDL-very low density lipoproteins
-contribute to increased fatty plaque formation
f) Fill in the blanks:
There are two sources of cholesterol in the body, in foods we _ingest______and formed by the _liver______.
g) What are some therapies used to reduce blood cholesterol levels?
-exercise, diet and drugs
h) Match the desirable levels of blood cholesterol for adults
1 - total cholesterol _2___under 130mg/dl
2 - LDL _1___under 200 mg/dl
3 - HDL _4___range of 10-190mg/dl (normally)
4 - triglycerides _3___over 40mg/dl
i) What is a:
· myocardial infarction(MI)?-death to an area of heart muscle from lack of O2, replaced with scar tissue
· angina pectoris?-heart pain from ischemia (lack of sufficient blood to a body part due to obstruction or constriction of a blood vessel) of cardiac muscle
j) What are some methods used in treating blood clots?
-clot dissolving drugs (streptokinase & heparin)
-balloon angioplasty