Study Guide - Heart and Peripheral Vascular
Concept Overview: Perfusion
- Many mechanisms facilitate or impair perfusion of oxygenated blood
- All tissues require perfusion of oxygenated blood
- Blood flow supplies oxygen and nutrients so tissues can perform their functions
o Skin
o Kidneys to produce urine
o Brain for intracranial regulation
o GI tract for metabolism
o Muscles and nerves for motion
- Pain results when perfusion is interrupted
- All of these physiologic concepts are interrelated
Anatomy and Physiology:
- Cardiovascular system:
o Transports oxygen, nutrients, and other substances to body’s tissues
o Carries metabolic waste products to kidneys and lungs
- This dynamic system is able to adjust to changing demands for blood by:
o Constricting or dilating blood vessels
o Altering cardiac output
A&P: Heart and Great Vessels
- Heart is a pump:
o Beats 60 to 100 times a minute without rest
o Responds to both external and internal demands
o Each side has two chambers:
Atrium
Ventricle
o Right side:
Receives blood from superior vena and inferior vena cava
Pumps blood through pulmonary arteries to pulmonary circulation
o Left side:
Receives blood from pulmonary veins
Pumps blood through aorta into systemic circulation
- Upper part of the heart is the base
- Lower left ventricle is the apex
- Heart lies behind sternum and above diaphragm in mediastinum
- Lies at an angle so right ventricle makes up most of anterior surface and left ventricle lies
left and posteriorly
- Pulmonary arteries and aorta are termed the great vessels.
- Aorta curves upward out of left ventricle and bends posteriorly and downward just
above sternal angle
, - Pulmonary arteries emerge from superior aspect of right ventricle near third intercostal
space
Pericardium and Cardiac muscle
- Heart wall has three layers: Pericardium, myocardium, and endocardium
o Heart encased in pericardium, which has a fibrous layer and two serous layers
o Pericardial space lies between two serous pericardium layers and contains
pericardial fluid to reduce friction as myocardium contracts and relaxes
- Middle layer: Myocardium – thick muscular tissue that contracts to eject blood from
ventricles
- Endocardium lines inner chambers and valves
Blood Flow through the Heart:
- Four valves govern blood flow through four chambers of heart:
o 2 atrioventricular (AV) valves
Separate atria from ventricles
Tricuspid valve on right
Mitral valve on left
o 2 Semilunar Valves
Half-moon shape
Aortic Semilunar valve opens from left ventricle into aorta
Pulmonic Semilunar valve opens from right ventricle into pulmonary
artery
Diastole:
- Ventricles relax and fill with blood from left and right atria
o Movement of blood from atria to ventricles is accomplished when pressure of
blood in atria becomes higher than pressure in ventricles
o Higher atrial pressures passively open AV valves, allowing blood to fill ventricles
o About 80% of blood from atria flows into relaxed ventricles
o Contraction of atria forces remaining 20% of blood into ventricles
This added atrial thrust is termed the atrial kick
o At the end of diastole, ventricles are filled with blood
Systole:
- Ventricles contact creating pressure that closes AV valves, preventing backflow of blood
into atria
o Ventricular pressure also forces semilunar valves to open, resulting in ejection of
blood into aorta from left ventricle and pulmonary arteries from right ventricle
o As blood is ejected ventricular pressure decreases, causing semilunar valves to
close
o Ventricles relax to begin diastole
Electric Conduction
- Heart stimulated by electric impulse originating in sinoatrial (SA) node in superior aspect
of right atrium and travels in internodal tracts to (AV) node
o *SA Node = Cardiac Pacemaker*, normally discharges 60 to 100 impulses per
minute
, o Electric impulses stimulate contractions of both atria and then the flow to AV
node in inferior aspect of right atrium
o Impulses are then transmitted to through series of branches and Purkinje fibers
in myocardium, which results in ventricular contraction
o AV node prevents excessive atrial impulses from reaching ventricles
o If SA node fails to discharge, AV node can generate ventricular contraction at a
SLOWER rate of 40 to 60 impulses per minute
o If both SA and AV nodes are ineffective, bundle branches may contract, but at a
very slow rate of 20 to 40 impulses per minute
Peripheral Vascular System
- Arteries, capillaries, and veins provide blood flow to and from tissues
- The tough and tensile arteries and their smaller branches, arterioles are subjected to
remarkable pressure generated from myocardial contraction
o Pressure within arteries is much higher than veins
- They maintain blood pressure by constricting or dilating in response to stimuli
- The veins and smaller branches, venules, are less sturdy, but more expansible, enabling
them to act as reservoir for extra blood, if needed, to decrease workload on heart
- Pressure within veins is low, compared with arterial circulation
- Valves in each vein keep blood flowing in a forward direction toward heart
Lymph System
- Works in collaboration with peripheral vascular system in removing fluid from interstitial
spaces
- As blood flow from arterioles into venules, oxygen and nutrient-rich fluid is forced out at
arterial end of capillary into interstitial space, and then into cells
- Waste products from cells flow through interstitial spaces to venous end of capillary
- Excess fluid left in interstitial spaces is absorbed by lymph system and carries to lymph
nodes throughout the body
- Lymphatic fluid is clear, composed mainly of water and a small amount of protein,
mostly albumin
- Lymph nodes are tiny oval clumps of lymphatic tissue, usually located in groups along
blood vessels
- In peripheral vascular system, lymph node locations of interest are arm, groin, and leg
- Brachial (axillary nodes) receive drainage from neck, chest, axilla, and arm
- Epitrochlear nodes on medial surface of arm above elbow may be palpable with
infection of the lower arm or hand
- In upper thigh, inguinal lymph nodes are superficial; they receive most of the lymph
drainage from great and small saphenous lymphatic vessels in legs
- In posterior surface of leg, behind knee, are popliteal nodes, which receive lymph from
medial portion of lower leg
Concept Overview: Perfusion
- Many mechanisms facilitate or impair perfusion of oxygenated blood
- All tissues require perfusion of oxygenated blood
- Blood flow supplies oxygen and nutrients so tissues can perform their functions
o Skin
o Kidneys to produce urine
o Brain for intracranial regulation
o GI tract for metabolism
o Muscles and nerves for motion
- Pain results when perfusion is interrupted
- All of these physiologic concepts are interrelated
Anatomy and Physiology:
- Cardiovascular system:
o Transports oxygen, nutrients, and other substances to body’s tissues
o Carries metabolic waste products to kidneys and lungs
- This dynamic system is able to adjust to changing demands for blood by:
o Constricting or dilating blood vessels
o Altering cardiac output
A&P: Heart and Great Vessels
- Heart is a pump:
o Beats 60 to 100 times a minute without rest
o Responds to both external and internal demands
o Each side has two chambers:
Atrium
Ventricle
o Right side:
Receives blood from superior vena and inferior vena cava
Pumps blood through pulmonary arteries to pulmonary circulation
o Left side:
Receives blood from pulmonary veins
Pumps blood through aorta into systemic circulation
- Upper part of the heart is the base
- Lower left ventricle is the apex
- Heart lies behind sternum and above diaphragm in mediastinum
- Lies at an angle so right ventricle makes up most of anterior surface and left ventricle lies
left and posteriorly
- Pulmonary arteries and aorta are termed the great vessels.
- Aorta curves upward out of left ventricle and bends posteriorly and downward just
above sternal angle
, - Pulmonary arteries emerge from superior aspect of right ventricle near third intercostal
space
Pericardium and Cardiac muscle
- Heart wall has three layers: Pericardium, myocardium, and endocardium
o Heart encased in pericardium, which has a fibrous layer and two serous layers
o Pericardial space lies between two serous pericardium layers and contains
pericardial fluid to reduce friction as myocardium contracts and relaxes
- Middle layer: Myocardium – thick muscular tissue that contracts to eject blood from
ventricles
- Endocardium lines inner chambers and valves
Blood Flow through the Heart:
- Four valves govern blood flow through four chambers of heart:
o 2 atrioventricular (AV) valves
Separate atria from ventricles
Tricuspid valve on right
Mitral valve on left
o 2 Semilunar Valves
Half-moon shape
Aortic Semilunar valve opens from left ventricle into aorta
Pulmonic Semilunar valve opens from right ventricle into pulmonary
artery
Diastole:
- Ventricles relax and fill with blood from left and right atria
o Movement of blood from atria to ventricles is accomplished when pressure of
blood in atria becomes higher than pressure in ventricles
o Higher atrial pressures passively open AV valves, allowing blood to fill ventricles
o About 80% of blood from atria flows into relaxed ventricles
o Contraction of atria forces remaining 20% of blood into ventricles
This added atrial thrust is termed the atrial kick
o At the end of diastole, ventricles are filled with blood
Systole:
- Ventricles contact creating pressure that closes AV valves, preventing backflow of blood
into atria
o Ventricular pressure also forces semilunar valves to open, resulting in ejection of
blood into aorta from left ventricle and pulmonary arteries from right ventricle
o As blood is ejected ventricular pressure decreases, causing semilunar valves to
close
o Ventricles relax to begin diastole
Electric Conduction
- Heart stimulated by electric impulse originating in sinoatrial (SA) node in superior aspect
of right atrium and travels in internodal tracts to (AV) node
o *SA Node = Cardiac Pacemaker*, normally discharges 60 to 100 impulses per
minute
, o Electric impulses stimulate contractions of both atria and then the flow to AV
node in inferior aspect of right atrium
o Impulses are then transmitted to through series of branches and Purkinje fibers
in myocardium, which results in ventricular contraction
o AV node prevents excessive atrial impulses from reaching ventricles
o If SA node fails to discharge, AV node can generate ventricular contraction at a
SLOWER rate of 40 to 60 impulses per minute
o If both SA and AV nodes are ineffective, bundle branches may contract, but at a
very slow rate of 20 to 40 impulses per minute
Peripheral Vascular System
- Arteries, capillaries, and veins provide blood flow to and from tissues
- The tough and tensile arteries and their smaller branches, arterioles are subjected to
remarkable pressure generated from myocardial contraction
o Pressure within arteries is much higher than veins
- They maintain blood pressure by constricting or dilating in response to stimuli
- The veins and smaller branches, venules, are less sturdy, but more expansible, enabling
them to act as reservoir for extra blood, if needed, to decrease workload on heart
- Pressure within veins is low, compared with arterial circulation
- Valves in each vein keep blood flowing in a forward direction toward heart
Lymph System
- Works in collaboration with peripheral vascular system in removing fluid from interstitial
spaces
- As blood flow from arterioles into venules, oxygen and nutrient-rich fluid is forced out at
arterial end of capillary into interstitial space, and then into cells
- Waste products from cells flow through interstitial spaces to venous end of capillary
- Excess fluid left in interstitial spaces is absorbed by lymph system and carries to lymph
nodes throughout the body
- Lymphatic fluid is clear, composed mainly of water and a small amount of protein,
mostly albumin
- Lymph nodes are tiny oval clumps of lymphatic tissue, usually located in groups along
blood vessels
- In peripheral vascular system, lymph node locations of interest are arm, groin, and leg
- Brachial (axillary nodes) receive drainage from neck, chest, axilla, and arm
- Epitrochlear nodes on medial surface of arm above elbow may be palpable with
infection of the lower arm or hand
- In upper thigh, inguinal lymph nodes are superficial; they receive most of the lymph
drainage from great and small saphenous lymphatic vessels in legs
- In posterior surface of leg, behind knee, are popliteal nodes, which receive lymph from
medial portion of lower leg
